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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),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.
이용성 ( Lee Yong Sung ) 아시아문화학술원 2017 인문사회 21 Vol.8 No.4
이 연구의 목적은 최근 개정 논의 중인 `지역신문발전지원 특별법`(지역신문법)의 주요 쟁점 분석이다. 첫 번째로 지역신문발전기금 지원대상 신문사를 선정하는데 상당한 영향을 미치고 있는 지역신문법의 입법 목적을 분석했다. 입법 목적 중에서 여론의 다원화, 지역사회 균형발전, 선택과 집중의 원칙을 살펴봤다. 두 번째로 한시법인 지역신문법의 상시법 전환, 세 번째로 신문관계기금의 중복, 네 번째로 우선지원대상사 지원제도의 개선 등의 쟁점을 논의했다. 연구결과에 따르면 지역신문법의 목적은 중앙 집중적인 언론에 맞설 수 있는 경쟁력 있는 지역신문 육성하는 것이다. 두 번째로 지역신문법의 상시법 전환은 강력한 선별지원제도라는 지역신문지원의 특수성이 계속 유지될 수 있을지를 고려해야 한다. 세 번째로 신문관계기금의 중복은 해결이 쉽지 않은 문제이다. 지원사업의 차별성을 확보하지 못하고 있기 때문이다. 네 번째로 우선지원대상사 제도는 지역신문법의 취지를 반영하여 계속 유지해야 할 것이다. 앞으로 지역신문법이 상시법이 되면 지원대상과 지원기준, 지원사업의 변화가 불가피하므로 이에 대한 연구도 필요할 것이다. The purpose of this study is to analyze the major issues of the `Special Act on Assistance in Development of Local Newspapers`(Local Newspaper Act), which is being discussed recently. First, I analyzed the legislative purpose of the `Local Newspaper Act`, which has a considerable influence on selecting the newspapers supported by the `Local Newspaper Development Fund.` I looked at the diversification of public opinion, the balanced development of the community, and the principles of choice and concentration among the legislative purposes. Second, there was discussion on issues such as the transition of the `Local Newspaper Act` to the Regular Law. Third, duplication of the newspaper funds, and fourth, improvement of Priority subsidy target company system. As a result of the research, the purpose of the Local Newspaper Act is to foster competitive local newspapers that can cope with centralized media. Second, it is necessary to consider whether the transition of the local newspaper law to the regular law can continue to maintain the specificity of the local newspaper support as a powerful Selective Subsidy system. Third, duplication of newspaper funds is a difficult problem to solve. This is because it does not ensure the differentiation of support projects. Fourthly, the Priority subsidy target company system should be maintained in accordance with the purpose of the Local Newspaper Act. If the local newspaper law becomes a regular law in the future, it will be necessary to study it because it is inevitable to change the support target, the support standard and the support project.