2017. 11. 22. 18:23

이 글에서는 현수선이 하이퍼코사인 곡선인 것과

이상적인 현수교의 주케이블 곡선이 포물선이라는 것을 보인다.

 

 

 

2. 다음으로 이상적인 현수교의 곡선방정식을 구해보자.


대부분의 현수교는 주 케이블의 질량에 비해 수직케이블(현수재)이 당기는 힘이 훨씬 클 것이므로

여기서 이상적인 현수교라 하면 주케이블에 질량이 없다고 가정한 것을 말한다.

이렇게 가정하면 곡선식을 구하기가 수월해진다는 장점도 있다.


아래 그림과 같이 질량이 없는 줄에 x 방향을 따라 등간격으로 줄이 달려 있고

각 줄마다 일정한 힘이 y 축 음의 방향으로 작용한다고 하자.

 

 

 

여기서 또 한가지 추가되는 문제는

수직 케이블(현수재)이 연결되는 지점마다 위쪽 케이블이 꺾일 것(즉 미분불가)이라는 점이다.

그러나 이 현수재가 연속적일 정도로 충분히 촘촘하다고 가정하면

그때는 주 케이블의 곡선도 미분가능한 것으로 가정하는 것이 무리가 없으며

주 케이블에 작용하는 장력의 방향 역시 접선의 방향과 같다고 할 수 있을 것이다.


따라서 일단은 현수교의 모델링을 자연스럽게 유도하기 위해

현수재는 주 케이블에 대해 충분히 촘촘히(연속적으로) 달려 있다고 가정하고

주 케이블의 곡선도 미분 가능하다고 가정하여 곡선식을 구해보자.

 

 

 

(주 케이블의 질량을 무시하지 않을 때의 함수방정식은 아직 풀지 못하였습니다.

혹시 해법을 알고 계신분은 댓글좀 부탁드립니다.^^;)

Posted by 역도부
2017. 11. 11. 20:02

트럼프 국회 연설문.hwp

Assembly Speaker Chung, distinguished members of this Assembly, ladies and gentlemen: Thank you for the extraordinary privilege to speak in this great chamber and to address your people on behalf of the people of the United States of America.

In our short time in your country, Melania and I have been awed by its ancient and modern wonders, and we are deeply moved by the warmth of your welcome.

Last night, President and Mrs. Moon showed us incredible hospitality in a beautiful reception at the Blue House. We had productive discussions on increasing military cooperation and improving the trade relationship between our nations on the principle of fairness and reciprocity.  

Through this entire visit, it has been both our pleasure and our honor to create and celebrate a long friendship between the United States and the Republic of Korea.

This alliance between our nations was forged in the crucible of war, and strengthened by the trials of history. From the Inchon landings to Pork Chop Hill, American and South Korean soldiers have fought together, sacrificed together, and triumphed together.

Almost 67 years ago, in the spring of 1951, they recaptured what remained of this city where we are gathered so proudly today. It was the second time in a year that our combined forces took on steep casualties to retake this capital from the communists.

Over the next weeks and months, the men soldiered through steep mountains and bloody, bloody battles. Driven back at times, they willed their way north to form the line that today divides the oppressed and the free. And there, American and South Korean troops have remained together holding that line for nearly seven decades. (Applause.)

By the time the armistice was signed in 1953, more than 36,000 Americans had died in the Korean War, with more than 100,000 others very badly wounded. They are heroes, and we honor them. We also honor and remember the terrible price the people of your country paid for their freedom. You lost hundreds of thousands of brave soldiers and countless innocent civilians in that gruesome war.  

Much of this great city of Seoul was reduced to rubble. Large portions of the country were scarred -- severely, severely hurt -- by this horrible war. The economy of this nation was demolished.  

But as the entire world knows, over the next two generations something miraculous happened on the southern half of this peninsula.  

Family by family, city by city, the people of South Korea built this country into what is today one of the great nations of the world.  

And I congratulate you. (Applause.) In less than one lifetime, South Korea climbed from total devastation to among the wealthiest nations on Earth.  

Today, your economy is more than 350 times larger than what it was in 1960. Trade has increased 1,900 times. Life expectancy has risen from just 53 years to more than 82 years today.

Like Korea, and since my election exactly one year ago today, I celebrate with you. (Applause.) The United States is going through something of a miracle itself. Our stock market is at an all-time high. Unemployment is at a 17-year low. We are defeating ISIS.

We are strengthening our judiciary, including a brilliant Supreme Court justice, and on, and on, and on.  

Currently stationed in the vicinity of this peninsula are the three largest aircraft carriers in the world loaded to the maximum with magnificent F-35 and F-18 fighter jets. In addition, we have nuclear submarines appropriately positioned. The United States, under my administration, is completely rebuilding its military and is spending hundreds of billions of dollars to the newest and finest military equipment anywhere in the world being built, right now. I want peace through strength. (Applause.)  

We are helping the Republic of Korea far beyond what any other country has ever done. And, in the end, we will work things out far better than anybody understands or can even appreciate. I know that the Republic of Korea, which has become a tremendously successful nation, will be a faithful ally of the United States very long into the future. (Applause.)

What you have built is truly an inspiration. Your economic transformation was linked to a political one. The proud, sovereign, and independent people of your nation demanded the right to govern themselves. You secured free parliamentary elections in 1988, the same year you hosted your first Olympics.  

Soon after, you elected your first civilian president in more than three decades. And when the Republic you won faced financial crisis, you lined up by the millions to give your most prized possessions -- your wedding rings, heirlooms, and gold “luck keys” -- to restore the promise of a better future for your children. (Applause.)  

Your wealth is measured in more than money -- it is measured in achievements of the mind and achievements of spirit. Over the last several decades, your scientists of engineers -- have engineered so many magnificent things. You‘ve pushed the boundaries of technology, pioneered miraculous medical treatments, and emerged as leaders in unlocking the mysteries of our universe.  

Korean authors penned roughly 40,000 books this year. Korean musicians fill concert halls all around the world. Young Korean students graduate from college at the highest rates of any country. And Korean golfers are some of the best on Earth. (Applause.)

In fact -- and you know what I’m going to say -- the Women‘s U.S. Open was held this year at Trump National Golf Club in Bedminster, New Jersey, and it just happened to be won by a great Korean golfer, Sung-hyun Park. An eighth of the top 10 players were from Korea. And the top four golfers -- one, two, three, four -- the top four were from Korea. Congratulations. (Applause.)  
Congratulations. And that’s something. That is really something.

Here in Seoul, architectural wonders like the Sixty-Three Building and the Lotte World Tower -- very beautiful -- grace the sky and house the workers of many growing industries.

Your citizens now help to feed the hungry, fight terrorism, and solve problems all over the world. And in a few months, you will host the world and you will do a magnificent job at the 23rd Olympic Winter Games. Good luck. (Applause.)  

The Korean miracle extends exactly as far as the armies of free nations advanced in 1953 -- 24 miles to the north. There, it stops; it all comes to an end. Dead stop. The flourishing ends, and the prison state of North Korea sadly begins.  

Workers in North Korea labor grueling hours in unbearable conditions for almost no pay. Recently, the entire working population was ordered to work for 70 days straight, or else pay for a day of rest.  

Families live in homes without plumbing, and fewer than half have electricity. Parents bribe teachers in hopes of saving their sons and daughters from forced labor. More than a million North Koreans died of famine in the 1990s, and more continue to die of hunger today.

Among children under the age of five, nearly 30 percent of afflicted -- and are afflicted by stunted growth due to malnutrition. And yet, in 2012 and 2013, the regime spent an estimated $200 million -- or almost half the money that it allocated to improve living standards for its people -- to instead build even more monuments, towers, and statues to glorify its dictators.

What remains of the meager harvest of the North Korean economy is distributed according to perceived loyalty to a twisted regime.  

Far from valuing its people as equal citizens, this cruel dictatorship measures them, scores them, and ranks them based on the most arbitrary indications of their allegiance to the state. Those who score the highest in loyalty may live in the capital city. Those who score the lowest starve. A small infraction by one citizen, such as accidently staining a picture of the tyrant printed in a discarded newspaper, can wreck the social credit rank of his entire family for many decades.  

An estimated 100,000 North Koreans suffer in gulags, toiling in forced labor, and enduring torture, starvation, rape, and murder on a constant basis.  

In one known instance, a 9-year-old boy was imprisoned for 10 years because his grandfather was accused of treason. In another, a student was beaten in school for forgetting a single detail about the life of Kim Jong-un.  

Soldiers have kidnapped foreigners and forced them to work as language tutors for North Korean spies.  

In the part of Korea that was a stronghold for Christianity before the war, Christians and other people of faith who are found praying or holding a religious book of any kind are now detained, tortured, and in many cases, even executed.  

North Korean women are forced to abort babies that are considered ethnically inferior. And if these babies are born, the newborns are murdered.  

One woman’s baby born to a Chinese father was taken away in a bucket. The guards said it did not “deserve to live because it was impure.”  

So why would China feel an obligation to help North Korea?

The horror of life in North Korea is so complete that citizens pay bribes to government officials to have themselves exported aboard as slaves. They would rather be slaves than live in North Korea.  

To attempt to flee is a crime punishable by death. One person who escaped remarked, “When I think about it now, I was not a human being. I was more like an animal. Only after leaving North Korea did I realize what life was supposed to be.”  

And so, on this peninsula, we have watched the results of a tragic experiment in a laboratory of history. It is a tale of one people, but two Koreas. One Korea in which the people took control of their lives and their country, and chose a future of freedom and justice, of civilization, and incredible achievement. And another Korea in which leaders imprison their people under the banner of tyranny, fascism, and oppression. The result of this experiment are in, and they are totally conclusive.  

When the Korean War began in 1950, the two Koreas were approximately equal in GDP per capita. But by the 1990s, South Korea’s wealth had surpassed North Korea‘s by more than 10 times. And today, the South’s economy is over 40 times larger. You started the same a short while ago, and now you’re 40 times larger. You‘re doing something right.

Considering the misery wrought by the North Korean dictatorship, it is no surprise that it has been forced to take increasingly desperate measures to prevent its people from understanding this brutal contrast.  

Because the regime fears the truth above all else, it forbids virtually all contact with the outside world. Not just my speech today, but even the most commonplace facts of South Korean life are forbidden knowledge to the North Korean people. Western and South Korean music is banned. Possession of foreign media is a crime punishable by death. Citizens spy on fellow citizens, their homes are subject to search at any time, and their every action is subject to surveillance. In place of a vibrant society, the people of North Korea are bombarded by state propaganda practically every waking hour of the day.  

North Korea is a country ruled as a cult. At the center of this military cult is a deranged belief in the leader’s destiny to rule as parent protector over a conquered Korean Peninsula and an enslaved Korean people.  

The more successful South Korea becomes, the more decisively you discredit the dark fantasy at the heart of the Kim regime.  

In this way, the very existence of a thriving South Korean republic threatens the very survival of the North Korean dictatorship.  

This city and this assembly are living proof that a free and independent Korea not only can, but does stand strong, sovereign, and proud among the nations of the world. (Applause.)

Here, the strength of the nation does not come from the false glory of a tyrant. It comes from the true and powerful glory of a strong and great people -- the people of the Republic of Korea -- a Korean people who are free to live, to flourish, to worship, to love, to build, and to grow their own destiny.  

In this Republic, the people have done what no dictator ever could -- you took, with the help of the United States, responsibility for yourselves and ownership of your future. You had a dream -- a Korean dream -- and you built that dream into a great reality.

In so doing, you performed the miracle on the Hahn that we see all around us, from the stunning skyline of Seoul to the plains and peaks of this beautiful landscape. You have done it freely, you have done it happily, and you have done it in your own very beautiful way.

This reality -- this wonderful place -- your success is the greatest cause of anxiety, alarm, and even panic to the North Korean regime. That is why the Kim regime seeks conflict abroad -- to distract from total failure that they suffer at home.  

Since the so-called armistice, there have been hundreds of North Korean attacks on Americans and South Koreans. These attacks have included the capture and torture of the brave American soldiers of the USS Pueblo, repeated assaults on American helicopters, and the 1969 drowning [downing] of a U.S. surveillance plane that killed 31 American servicemen. The regime has made numerous lethal incursions in South Korea, attempted to assassinate senior leaders, attacked South Korean ships, and tortured Otto Warmbier, ultimately leading to that fine young man’s death.  

All the while, the regime has pursued nuclear weapons with the deluded hope that it could blackmail its way to the ultimate objective. And that objective we are not going to let it have. We are not going to let it have. All of Korea is under that spell, divided in half. South Korea will never allow what‘s going on in North Korea to continue to happen.

The North Korean regime has pursued its nuclear and ballistic missile programs in defiance of every assurance, agreement, and commitment it has made to the United States and its allies. It’s broken all of those commitments. After promising to freeze its plutonium program in 1994, it repeated [reaped] the benefits of the deal and then -- and then immediately continued its illicit nuclear activities.  

In 2005, after years of diplomacy, the dictatorship agreed to ultimately abandon its nuclear programs and return to the Treaty on Non-Proliferation. But it never did. And worse, it tested the very weapons it said it was going to give up. In 2009, the United States gave negotiations yet another chance, and offered North Korea the open hand of engagement. The regime responded by sinking a South Korean Navy ship, killing 46 Korean sailors. To this day, it continues to launch missiles over the sovereign territory of Japan and all other neighbors, test nuclear devices, and develop ICBMs to threaten the United States itself. The regime has interpreted America’s past restraint as weakness. This would be a fatal miscalculation. This is a very different administration than the United States has had in the past.

Today, I hope I speak not only for our countries, but for all civilized nations, when I say to the North: Do not underestimate us, and do not try us. We will defend our common security, our shared prosperity, and our sacred liberty.  

We did not choose to draw here, on this peninsula -- (applause) -- this magnificent peninsula -- the thin line of civilization that runs around the world and down through time. But here it was drawn, and here it remains to this day. It is the line between peace and war, between decency and depravity, between law and tyranny, between hope and total despair. It is a line that has been drawn many times, in many places, throughout history. To hold that line is a choice free nations have always had to make. We have learned together the high cost of weakness and the high stakes of its defense.  

America’s men and women in uniform have given their lives in the fight against Nazism, imperialism, Communism and terrorism.  

America does not seek conflict or confrontation, but we will never run from it. History is filled with discarded regimes that have foolishly tested America’s resolve.

Anyone who doubts the strength or determination of the United States should look to our past, and you will doubt it no longer. We will not permit America or our allies to be blackmailed or attacked. We will not allow American cities to be threatened with destruction. We will not be intimidated. And we will not let the worst atrocities in history be repeated here, on this ground, we fought and died so hard to secure. (Applause.)  

That is why I have come here, to the heart of a free and flourishing Korea, with a message for the peace-loving nations of the world: The time for excuses is over. Now is the time for strength. If you want peace, you must stand strong at all times. (Applause.) The world cannot tolerate the menace of a rogue regime that threatens with nuclear devastation.

All responsible nations must join forces to isolate the brutal regime of North Korea -- to deny it and any form -- any form of it.  

You cannot support, you cannot supply, you cannot accept. We call on every nation, including China and Russia, to fully implement U.N. Security Council resolutions, downgrade diplomatic relations with the regime, and sever all ties of trade and technology.

It is our responsibility and our duty to confront this danger together -- because the longer we wait, the greater the danger grows, and the fewer the options become. (Applause.) And to those nations that choose to ignore this threat, or, worse still, to enable it, the weight of this crisis is on your conscience.  

I also have come here to this peninsula to deliver a message directly to the leader of the North Korean dictatorship: The weapons you are acquiring are not making you safer. They are putting your regime in grave danger. Every step you take down this dark path increases the peril you face.  

North Korea is not the paradise your grandfather envisioned. It is a hell that no person deserves. Yet, despite every crime you have committed against God and man, you are ready to offer, and we will do that -- we will offer a path to a much better future. It begins with an end to the aggression of your regime, a stop to your development of ballistic missiles, and complete, verifiable, and total denuclearization. (Applause.)  

A sky-top view of this peninsula shows a nation of dazzling light in the South and a mass of impenetrable darkness in the North. We seek a future of light, prosperity, and peace. But we are only prepared to discuss this brighter path for North Korea if its leaders cease their threats and dismantle their nuclear program.  

The sinister regime of North Korea is right about only one thing: The Korean people do have a glorious destiny, but they could not be more wrong about what that destiny looks like. The destiny of the Korean people is not to suffer in the bondage of oppression, but to thrive in the glory of freedom. (Applause.)  

What South Koreans have achieved on this peninsula is more than a victory for your nation. It is a victory for every nation that believes in the human spirit. And it is our hope that, someday soon, all of your brothers and sisters of the North will be able to enjoy the fullest of life intended by God.  

Your republic shows us all of what is possible. In just a few decades, with only the hard work, courage, and talents of your people, you turned this war-torn land into a nation blessed with wealth, rich in culture, and deep in spirit. You built a home where all families can flourish and where all children can shine and be happy.  

This Korea stands strong and tall among the great community of independent, confident, and peace-loving nations. We are nations that respect our citizens, cherish our liberty, treasure our sovereignty, and control our own destiny. We affirm the dignity of every person and embrace the full potential of every soul. And we are always prepared to defend the vital interests of our people against the cruel ambition of tyrants.  

Together, we dream of a Korea that is free, a peninsula that is safe, and families that are reunited once again. We dream of highways connecting North and South, of cousins embracing cousins, and this nuclear nightmare replaced with the beautiful promise of peace.

Until that day comes, we stand strong and alert. Our eyes are fixed to the North, and our hearts praying for the day when all Koreans can live in freedom. (Applause.)

Thank you. (Applause.) God Bless You. God Bless the Korean people. Thank you very much. Thank you. (Applause.)  

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Posted by 역도부
2017. 10. 18. 17:08

Russian Opisometer (with no scale calculator)

 

 

 

 

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2017. 10. 13. 16:18

PARKER Insignia Sterling Silver Pencil 0.5mm

 

 

 

 

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Posted by 역도부
2017. 8. 15. 16:52

선악과는 율법, 생명나무는 예수 그리스도다.


선악과에는 '먹지 말라' 라는 명령과,

선악과를 먹으면 '정녕 죽는다'는 말씀이 달려 있었다.


인류는 선악과를 통하여 '선'과 '악'을 알게 되었다.

'선'은 하나님이고, '악'은 하나님을 떠나 있는 피조물이다.


율법은 'Do'와 'Don't'로 이루어져 있다.

이 율법은 인류에게 떨어지는 즉시 사망과 재앙으로 이어진다.

왜냐하면 인간은 스스로의 힘으로 '선'을 이룰 수 없기 때문이다.

율법이 인류에게 완전한 재앙인 이유는

피조물은 피조물일 뿐, 신이 아니기 때문인 것이다.


그래서 (다행히도) 율법은 몽학선생이다.

율법은 '하라'와 '하지 말라'라는 명령으로 되어 있지만

율법을 통해 인간이 배우는 것은 결국

'하라'라는 것은 할수가 없고, '하지 말라'라는 것은 안할수가 없는,

피조물의 현실에 대한 인식이다.


이렇게 율법은, 인간의 피조물로서의 상태를 가르쳐준다.

율법은, 하나님의 의의 법을 가르쳐줄 뿐 아니라

결국 율법을 지킬 수 없다는 것을 가르쳐줌으로써

'몽학 선생'이라고 불리는 것이다.

율법은 숯덩어리처럼 인간의 정신을 번쩍 들게 한다.

왜냐하면 초보적 상태의 인간은 늘

스스로의 힘으로 살 수 있다고 착각하여

선을 획득하려고 하는 생각에 빠져 있기 때문에

창조주의 법인 율법을 통하여 그것이 불가능하다는 것을 알게 되는 것이다.

즉 모든 인간이 범법자요, 스스로 살 수 없는 존재임을 배우게 되는 것이다.


몽학선생인 율법은 그 자체로 비유이며, 그림자이다.

그런데 그 율법을 자신의 참 남편으로 알고

그 율법을 붙잡아 생명의 길을 얻으려 하는 사람은

헤어나올 수 없는 선악 논리구조의 굴레에 갇혀

'하나님의 불필요함'을 계속 고집하다가

저주를 면할 수 없게 된다.


'선악과적 인간' 에서 탈피하여 '생명나무적 인간'으로 들어가는 것은

구약에서 신약으로

율법에서 복음으로

사망에서 생명으로

자기에게서 예수로

피조물에게서 창조자로

들어가는 것이다.


이렇게 생명나무로 들어간 자는

용서와 화해, 평화의 의미를 안다.

그는 선악의 주체로 사는 '바리세인적' 인간상을 버리고

용서와 화해, 평화의 패러다임 속에서 '예수적'인 삶을 살게 된다.

옳고 그름에 대한 선악 판단의 주체에서 벗어나

오직 완전한 선이신 예수 안에서의 삶을 통하여

생명과 의, 평화의 삶을 살게 되고

용서를 실현하면서 사는 사람이 되는 것이다.

Posted by 역도부
2017. 6. 6. 16:33

이 문제에서 많은 논란이 된 주제는

'과연 g(x)를 확정하기 전에 f(0)=0 임을 알수 있는가?' 였던 것 같습니다.


사실 저는 문제를 풀 때

x→0+이면 G(x)→-∞ 이므로 G'(x)→∞ 일 것으로 생각하여

f(0)=0 으로 두고 풀었습니다.

그러나 후에 이부분을 식으로 증명할 수 있을지 생각해 보았을 때

이러한 논리는 일반적으로는 거짓임을 알게 되었습니다.

물론 문제 상황에서는 참이지만

이것이 참임을 보이려면 

결국 g(x)가 다항식이라는 사실을 구체적으로 적용해야 하는 것입니다.


여기서는 좀더 간단한 풀이를 소개해봅니다.

 

 

     

 

Posted by 역도부
2017. 3. 21. 19:34

오늘 잠자리에 들다가 번개처럼 떠오른 생각이 있었습니다.

제가 어제 잠을 안잤기 때문에 오늘 자려다가 머리를 맞은것처럼 다시 일어났습니다.


물론 저는 김우현 감독님께서 할아버지의 맨발에 대해 '자기의를 가리는 장치'라고 말씀한 것을 들었습니다.


그런데 만약 어느 독실하고 성경에 능통한 기독교인이 평생 맨발로 다니면서 단 한 순간도 신발을 신지 않았다고 합시다.

그 진짜 이유가 무엇이겠습니까? 뭔가를 가리기 위해서 아무도 안보는 곳에서조차 맨발로 다니셨을까요?

세상 어느 누구보다도 온전한 정신으로 사신 그분이 의도적으로 그런 모습을 선택한 진짜 이유가 무엇이겠습니까?



그것은 첫번째로, 이 세상에서의 모든 소유나 권리에 대한 완전한 포기를 의미합니다.

성경에서 신발은 땅이나 기업에 대한 소유권을 상징합니다.

룻기에 보면 친족권을 포기할 때, 신발을 벗어서 권리를 받을 사람에게 주는 장면이 나옵니다.


팔복 동영상을 보면 최춘선 할아버지가 자기 재산이 자기것이 아니라고 말씀하는 부분이 나옵니다.

말씀만 그렇게 한게 아니라 실제로 그렇게 사셨습니다.

그분은 자신의 학업, 지식, 권력, 물질, 부모배경 등 이 세상에 관련된 모든 것을 완전히 포기했습니다.

심지어 독립운동 투사로 도장만 찍으면 받을 수 있는 국가 보조도 안받으신 분입니다.

결국 세상이 주는 어떤 안락함도 의도적으로 거부하신 것입니다.

그러한 그분의 삶을 가장 단적으로 보여주는 것이 바로 그분의 맨발입니다.


창세기에는 아브라함이 그돌라오멜 연합군을 격파한 후에 가나안 왕들의 소유였던 전리품을 단 한푼도 취하지지 않는 장면이 나옵니다.

아브라함의 기업은 세상 것과는 전혀 섞일 수 없는 성질의 것이었기 때문입니다.

아브라함은 그 대신 멜기세덱으로부터 떡과 포도주를 받습니다.

최춘선 할아버지는 자신의 맨발을 볼 때마다 이 세상에서는 나그네로 살아가는 천국 시민으로서의 자신을 보았을 것입니다.



두번째로는, 그분의 진짜 소유가 하늘 나라에 있다는 것을 의미합니다.

동영상을 보면 신발을 왜 안신냐는 질문에 "통일되면 신어요" 라고 대답하는 부분이 나옵니다.

그분이 말씀하신 '통일 대한민국'이 무엇이겠습니까? 아픔과 분단이 없는 완전해진 세상을 말합니다.

완전한 모습으로 회복될 그 세상이 오면, 비로소 그곳에서 자신의 기업을 누리겠다고 말씀하는 것입니다.


그분은 마치 성경에 자신의 전재산을 팔아서 밭을 산 사람처럼,

하늘나라의 감추어진 보화를 사모하여 이땅에서의 모든 소유를 포기하셨습니다.


히브리서에는 허다한 믿음의 증인들이 나옵니다.

그들은, 진정으로 바라는 것이 이 땅에 있지 않았기에, 세상이 감당할 수 없는 모습으로 살았다고 쓰여있습니다.

그리고 하나님께서 그들을 위해 진짜로 도성을 예비하셨다는 말씀도 나와있습니다.


이정도는 돼야 믿음이라고 할 수 있을 것 같습니다.


결론 : "영원히 살 곳이 이땅이 아님을 알기에, 세상이 주는 안락함을 의도적으로 거부한다."

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Posted by 역도부
2017. 2. 28. 10:39

Year : 1980s

Length : 130mm

Diameter : 8mm

Weight : 11g

Lead size : 0.3mm

 

 

 

 

 

 

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Posted by 역도부
2017. 2. 20. 11:52

 

 

Mitsubishi mechanical pencil Golden Axe M3-50

Fixed sleeve, Plastic barrel

Lead diameter 0.3mm

Length          141mm

Weight          12g

 

 

 

 

 

 

 

Posted by 역도부
2017. 2. 2. 10:54

 

1. Face : It's not screw. It's painting.

 

 

 

2. Side : It's not patched plate. It's engraving & painting.

Posted by 역도부
2017. 1. 2. 00:19

자전거는 왜 타는가?

사람들마다 여러가지 이유가 있겠지만 나는 한마디로 '자유' 때문에 타는 것 같다.

내 길을 나의 패이스대로, 내 힘으로 갈 수 있다는 점 때문이다.

그것은 때로는 삶의 의미를 좀더 명확하게 하는데 도움이 된다고 느낀다.

 


공학이 계속 발전하면서 자전거에도 점점 더 좋은 기술이 적용되어 가고 있다.

 


기술이 발전하는 것이야 좋은 일이지만

때로는 그 기술에 종속되어야 한다는 단점이 생기고,

어느 순간 내가 자전거를 타는 이유인 '자유'를 포기해야 할 때도 생긴다.

 

그중에 indexed shifting이라는 것이 있는데

이는 기어비를 회사에서 제공한대로만 사용해야 하고 호환성이나 개성은 별로 인정해주지 않는 기술이다.


단적으로 말해서 수많은 사람들이 자전거를 산 이후로 단 한번도 쓰지 않을 코그를 돈 주고 사고 있다.

솔까말 생활용 자전거의 변속은 뒷쪽 5단 정도면 충분할 것이다.

자전거에 별 관심을 두지 않는 사람들은 자전거로 언덕을 오르는 것과 내리막에서 페달링을 하는 것은 상상하지 못한다.

 


내가 교통용으로 사용하기에는 아래처럼 34,46T 체인링에다가 11-19T면 충분한데

요즘시대에 적당한 성능을 보여주면서 8단에 11-19T로 생산되는 스프라켓은 눈씻고 찾아볼 수 없다.

 


아래는 간단히 기어비를 계산해본 것이다.

 

 

 

까만 숫자가 기어비고 파란숫자는 기어 한칸 이동시 발생되는 차이에 100을 곱한 것이다.

이 숫자는 체감상 20정도가 적당해서

30을 넘으면 간격이 크다고 느끼게 되고, 반대로 12 이하가 되면 변속을 했다는 느낌이 별로 안오게 된다.


예전(90년대)에 53-39T 체인링이 유행할때 난 도무지 이해할 수 없었다.

자전거 타는 사람이 모두 TDF선수가 아닌데 왜 그렇게 무식하고 큰 체인링을 써야 한단말인가.

난 아무래도 이건 말이 안된다고 생각했다.

그래서 나는 그때 컴팩트 체인링을 찾았었다.

그리고 그후 어느순간 컴팩트 체인링은 유행을 타게 되었다.


현재 나로서는 교통용으로쓸 체인링은 34-46T면 충분하다.

예를 들어 기어비 50-11T 조합은 내리막에서도 전력으로 달려야 하는 대회에서나 쓸 것이지 혼자 교통용으로 탈 때는

도무지 쓸 기회가 없는 것이다.

그리고 34-23T 조합도 역시 길고 가파른 업힐에서나 쓸 것이지 교통용으로는 굳이 필요하지 않은 것이다.


이렇게 내가 원하는 기어비를 만들려고 하면 결국

Indexed Shifting이라는 기술과는 이별을 고해야 한다.

그리고 어느정도의 시간동안 고독한 세팅을 거쳐야만 한다.

 

 

50-34T 체인링. 46-34T 체인링으로 바꿀 것이다.  

 

 

나만의 8단 11-19T 커스텀 스프라켓 조합.

11,12,13,14,15,16,17,19T 낫장으로 조합한 것이다.

인덱스드 쉬프팅의 안락함에게 이별을 고하고 있다.

 

 

규격에 맞는 것만 쓰라고 하는 시마노의 경고는 개나 줘버리자.

산악용 디레일러에 로드용 숏케이지를 결합하여 만든 나름 커스텀 디레일러.

지난 몇년간 아무 문제 없이 잘 작동해주고 있다. 이렇게 만든 이유는

이 기어 조합의 전체 capacity가 (46-34)+(19-11) = 20 밖에 되지 않으므로 숏케이지로 충분하기 때문이다.

게다가 케이지가 길어지면 그에 따른 무게와, 체인의 출렁거림,  변속트러블의 가능성이 모두 커지기 때문에

가급적이면 짧은 것이 대부분 유리하다.

 

 
오랫동안 나의 동반자가 되어온 시마노의 (무려) 썸 프릭션 쉬프터

10년전만 해도 막자전거에 흔히 사용됐지만 지금은 돈주고도 못산다.


저기에 나만의 인덱스드 기술이 적용되었다. 하얀 눈금끼리 맞추면 뒷디레일러 풀리와 코그가 일치하게 되는 것이다.

나는 저 인덱스드 기술에 상당한 자부심과 만족감을 느낀다.


결국 이번에 프레임을 바꾸면서 앞디레일러의 호환성 문제가 생겨버렸다.

엠티비용 3단 쉬프터는 트림펑션(trim function)이 없기 때문에 마찰음을 피할 수 없게 된 것이다.

말이야 그럴듯한 트림펑션이지만 실은 인덱스드 기술의 무식함을 보여주는 것이다.

저 유명한 암스트롱께서도 한참 동안 앞변속은 컨트롤레버 대신 간지나는 다운튜브 쉬프터를 사용해주셨다.

아마도 시마노는 암스트롱 때문에 트림펑션을 개발했지 싶다..

 

 

 

Microshift 사의 SL-A09 전격 구입.

나는 인덱스드와 프릭션 모드 선택이 가능한 SL-T09 를 주문했는데

중국놈들이 값싸고 인덱스드밖에 안되는 SL-A09를 보냈다.

아무래도 속여파는 것 같다.


해외주문으로 20일이나 기다려서 받았는데 환불하려면 또 한달을 기다려야만 한다ㅠ

결국 나는 환불 대신 할인을 요구해서 일정금액을 돌려받았다.

나쁜놈들.


내가 필요한 것은 프릭션이지 인덱스드가 아닌데 어떡할 것인가?

 

 

이게 인덱스드 전용이라지만 나는 프릭션 모드로 개조할 자신이 있었으므로 일단 분해했다.

저기 위쪽 왼편에 인덱스드 쉬프팅을 위한 구슬 두개와 홈이 파인 스패이서가 보인다.

저 핵심 부품을 교환하고 마찰되도록 바꿔주기만 하면 개조는 끝날 것이다.

이게 다 나쁜 중국놈들 때문에 벌어진 일이다.
 

 

일단 앞변속기만 교체. 현재까지 잘 작동하고 아울러 무게도 줄였다.

아무래도 콘트롤레버는 프릭션 쉬프터보다 무거울 수밖에 없다.

 


라이딩 자세에서 바라본 모습.

 

 

 

내친김에 뒷변속기까지 교체

 

 

여기에 다시 나만의 인덱스드 기술 적용.


짧지 않은 시간 동안 애정을 들여가며 서서히 바뀌어 가고 있는 자전거를 보니 뿌듯하다.

 

 

그런데 좀 문제는 나만 뿌듯한 것 같다는 것이다...


이런거 한다고 누가 먼저 칭찬해주지 않는다.

이런거 타고 다닌다고 누가 먼저 알아봐주지는 않는다..

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Posted by 역도부
2016. 12. 30. 23:35

Norma Merkuria 190

 

Instruction (manual) scan and its english translation (by google) pdf file : Norma Merkuria Instruction.zip

 

 

 

 

 

Below : For those who want to calculate error rate of this product.

 

 

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Posted by 역도부
2016. 12. 14. 10:51

 

 

 

Operational principle of this tool is same with that of Archimedes' Trammel.

 

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Posted by 역도부
2016. 12. 12. 00:11

The latus rectum of a conic section is the chord through a focus parallel to the conic section directrix (Coxeter 1969).

 

 

 

 

 

Posted by 역도부
2016. 9. 26. 20:05

Limit of (x-sinx)/x^3 when x->0

(without using L'hospital's rule)

 

 

Posted by 역도부
2016. 7. 21. 02:05

MOLNIJA Pocket Watch

Caliber: 3602

 

 

 

 

 

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Posted by 역도부
2016. 7. 18. 23:50

Pentel

Smash 0.3mm

Q1003

-Polished

 

 

 

 

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Invicta Coalition Forces 0963

Sellita SW500 Automatic Movement

Chronograph, Day, Date

537/1000 Limited Edition

Titanium case, See-through back

 

(after sand papering on band)

 

 

 

(below : after polishing and line painting on bezel)

 

 

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 여기서 ii)의 경우 f(x)가 무한대로 발산하는 조건은 불필요한것으로 보이는데 이부분에 대해 조언 부탁드립니다.  

 

 

 

Posted by 역도부