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원자력발전소 운전환경에서 SA508 Gr. 1A 저합금강의 피로 수명 분석
이용성,김태순,이재곤,Lee, Yong Sung,Kim, Tae Soon,Lee, Jae Gon 한국압력기기공학회 2010 한국압력기기공학회 논문집 Vol.6 No.1
Fatigue has been known as a major degradation mechanism of ASME class 1 components in nuclear power plants. Fatigue damage could be accelerated by combined interaction of several loads and environmental factors. However, the environmental effect is not explicitly addressed in the ASME S-N curve which is based on air at room temperature. Therefore many studies have been performed to understand the environmental effects on fatigue behavior of materials used in nuclear power plants. As a part of efforts, we performed low cycle fatigue tests under various environmental conditions and analyzed the environmental effects on the fatigue life of SA508 Gr. 1a low alloy steel by comparing with higuchi's model. Test results show that the fatigue life depends on water temperature, dissolved oxygen and strain rate. But strain rate over 0.4%/s has little effect on the fatigue life. To find the cause of different fatigue life with ANL's and higuchi's model, another test performed with different heat numbered and heat treated materials of SA508 Gr. 1a. On a metallurgical point of view, the material with bainite microstructure shows much longer fatigue life than that with ferrite/pearlite microstructure. And the characteristics of crack propagation as different microstructure seem to be the main cause of different fatigue life.
플립칩의 반복 굽힘 시험 시 파손 특성에 관한 실험적 연구
이용성,정종설,김홍석,신기훈,Lee, Yong-Sung,Jeong, Jong-Seol,Kim, Hong-Seok,Shin, Ki-Hoon 한국생산제조학회 2009 한국생산제조학회지 Vol.26 No.3
In general, circuit board assemblies experience various mechanical loadings during assembly and in actual use. The repeated cyclic bending can cause electrical failures due to circuit board cracks, solder interconnects cracks, and the component cracks. In this paper, we report on the failure characteristics of semiconductor chips under the repeated cyclic bending. We first describe a new 4-point bending tester, which is developed according to JEDEC standard No. 22B113. The performance of the tester is then estimated through actual experiments. Test results reveal that the cracks first occur on the outer balls around 20,000 cycles and gradually propagate to the inner balls where cracks are found around 70,000 cycles.
이용성(Yong-Sung Lee),정종설(Jong-Seol Jeong),신기훈(Ki-Hoon Shin),정성균(Seong-Kyun Cheong) 한국생산제조학회 2007 한국생산제조시스템학회 학술발표대회 논문집 Vol.2007 No.10
Circuit board assemblies experience various mechanical loadings during assembly and in actual use. The repeated cyclic bending can cause electrical failures due to circuit board cracks, solder interconnects cracks, and the component cracks. This paper presents a cylic bending tester developed especially for evaluating the reliability of board level flip chips under the repeated cyclic bending. The tester employs the concept of 4-point bending test and complies to JEDEC standard No. 22Bl13 that is intended to evaluate and compare the performance of surface mount electronic components in an accelerated test environment. The performance of the tester will be estimated through the cross check of the test results in the future work.
보드 레벨 플립칩의 4점 굽힘 시험 시 파단 특성 연구
이용성(Yong-Sung Lee),정종설(Jong-Seol Jeong),이재헌(Jae-Heon Lee),신기훈(Ki-Hoon Shin),정성균(Seong-Kyun Cheong) 한국생산제조학회 2008 한국생산제조시스템학회 학술발표대회 논문집 Vol.2008 No.5
In general, circuit board assemblies experience various mechanical loadings during assembly and in actual use. The repeated cyclic bending can cause electrical failures due to circuit board cracks, solder interconnects cracks, and the component cracks. In this paper, we report on the failure characteristics of board level flip chips under the repeated cyclic bending. We first describe a new 4-point bending tester, which is developed according to JEDEC standard No. 22B113. The performance of the tester is then estimated through actual experiments . Test results reveal that the cracks first occur on the outer balls around 20,000 cycles and gradually propagate to the inner balls where cracks are found around 70,000 cycles.
이용성(Yong-Sung Lee) 한국언론정보학회 2011 한국언론정보학보 Vol.56 No.4
이 논문은 1987년 정간법 제정을 계기로 구축된 신문의 소유규제 제도가 2005년 신문법으로 전부 개정되면서 강화되었고, 2009년에 다시 개정되면서 위기에 직면하게 되는 과정을 언론법제사적 측면에서 검토한다. 1987년, 헌법 제21조 제3항의 신문기능 법정주의에 근거해서 정립된 신문의 소유규제 제도는 2005년 신문법으로 강화되었다가 2006년 신문법 헌법소원 결정에 따라 위축되기 시작한다. 2009년 신문법과 방송법이 개정되면서 신문 방송 겸영규제, 복수신문 소유 규제 등은 존재하지 않게 되었다. 그 과정에서 야당도 신문방송의 제한적인 교차소유를 허용하였기 때문에 1987년에 형성된 신문소유 규제 제도는 해체 위기에 직면했다. 신문방송의 교차소유 허용 등의 규제완화가 미디어환경의 변화와 여론지배력의 추이 등을 장기적으로 검토하고 결정해야 할 정책적인 사안임에도 불구하고 이렇게 단기간에 도입하는 것은 위험한 일이다. 신문은 정치여론 형성에 있어서 지상파방송과 함께 강력한 미디어이다. 신문여론시장을 과점하고 있는 신문들의 여론지배력이 보도방송 영역까지 전이될 수 있다는 우려를 무시하기 어렵기 때문이다. 미디어소유 집중으로 정치적 다원주의가 위축되어 궁극적으로 민주주의가 위협받을 개연성이 있다는 점에서 신문 소유규제의 완화는 장기적인 사회적 논의가 전제되어야 할 것이다. This thesis reviews the process in which the regulation systems against ownership concentration of newspapers established with the opportunity of legislation of the periodical act in 1987 was reinforced as they were all amended to the newspaper act in 2005 and as they were again amended in 2009 it came to confront crisis in the aspect of press law legislation history. The regulation systems against ownership concentration of newspapers established based on the principle of legality of newspaper function in the Clause 3, the Article 21 of Constitution was reinforced as the newspaper act in 2005 and in 2006 they began to shrink following the Constitution Court decision against newspaper act. As newspaper act and broadcast act are revised in 2009, regulation against combining the management of newspapers with broadcast and regulation against owning multiple number of newspapers came not to exist. Because in this process, the opposition party also allowed limited cross-ownership of newspaper and broadcast, it can be said that the system of newspaper ownership regulation confronted the crisis of dissolution. The instruction of regulation alleviation in a short period of time in spite of the fact that regulation alleviation which allows cross-ownership of newspaper and broadcast is the matter of policy that should be decided after long-term review of the change of media environment and the progress of the power of domination of public opinion is dangerous. Newspapers are strong media with terrestrial broadcast in formation of public opinion on politics. It’s because it is difficult to ignore the worry that the power of domination of public opinion of the newspapers which are in oligopoly of newspaper public opinion market can be spreaded to the territory of report broadcast. From the point of view that there is probability for democracy to be ultimately threatened due to the shrink of political Darwinism caused by concentration of media ownership, the alleviation of ownership concentration of newspapers should have premise of long-term social discussion.
이용성(Yong-Sung Lee),김홍석(Hong Seok Kim),정성균(Seong-Kyun Cheong),최웅재(Ung-Jae Choi),김영근(Young-Keun Kim),박경래(Kyung-Rea Park),신기훈(Ki-Hoon Shin) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.1
컴파운더 보우는 리커브 보우와 비교하여 케이블 및 캠 풀리로 구성되는 지레시스템을 사용하여, 궁사가 보우를 최대 위치로 당기기 위해 필요로 하는 힘을 줄이는 동시에 더 많은 에너지를 축적할 수 있도록 해준다. 지금까지 컴파운더 보우의 효율 및 성능을 향상시키기 위해 경험적인 방법에 기초하여 많은 특허가 제안되었지만, 해석적인 방법에 대한 연구는 별로 없었다. 그러므로 본 연구에서는 컴파운더 보우 지레 시스템의 기구학적인 해석을 위한 방법을 제안하여 지레시스템의 캠 형상 및 보우 날개의 재질변화에 따른 효과를 설계자가 쉽게 예측할 수 있도록 하고자 한다. Compound bows use levering systems consisting of cables and cam pulleys to bend limbs that are much stiffer than those of recurve bows, thus storing more energy while requiring less force for the archer to hold the bow at a fully drawn position. Many patents have thus far been proposed to improve the efficiency and performance of compound bows through empirical methods, whereas only a few analytical methods have been proposed. In this light, this paper presents a method for the kinematic analysis of levering systems in compound bows so that a designer can easily predict the effects of changes in the cam profiles and limb materials.