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- 저자 : 이용성(Yong Sung Lee) (검색결과 186 건)
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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.
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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.
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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.
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Lysobacter capsici YS1215를 이용한 뿌리혹선충(Root-knot nematode)의 생물학적 방제
이용성(Yong-Sung Lee),박윤석(Yun-Suk Park),김선배(Sun-Bae Kim),김길용(Kil-Yong Kim) 한국토양비료학회 2013 한국토양비료학회지 Vol.46 No.2
The experiments were carried out to investigate the biocontrol potential of Lysobacter capsici YS1215 on root-knot nematode and to characterize its lytic enzyme activities. L. capsici YS1215 showed chitinase and gelatinase activities on the medium containing 0.5% chitin or 0.5% gelatin as substrates. Cell growth of L. capsici YS1215 was highest at 6 days, and the highest activities of chitinase (4.0 unit ml<SUP>-1</SUP>) and gelatinase (7.43 unit ml<SUP>-1</SUP>) were observed on 3 and 5 days after incubation, respectively. To investigate the effect of L. capsici YS1215 on tomato growth and nematode infection, the plants in pot trial were treated with bacterial culture (BC), half of bacterial culture (HBC), only bacterial medium (BM), tap water (TW) and commercial nematicide (CN). HBC treatd plants showed the higher shoot fresh weight and dry weight on 5<SUP>th</SUP>week after incubation while BM, HBC and BC had consistently higher values than TW at 9<SUP>th</SUP> week. HBC appeared to be the highest shoot fresh length at 9<SUP>th</SUP> week. Both CN and BC showed lower number of egg mass, root gall, and population of juveniles in soil compared to BC, HBC, BM and TW. These results suggest that L. capsici YS1215 with its strong ability of lytic enzyme production can be one of the most significant candidates for biocontrol agents against root-knot nematodes.
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다양한 형상비를 갖는 사각 CFRP 튜브의 굽힘 및 비틀림 특성
이용성 ( Yong Sung Lee ),정성균 ( Seong Kyun Cheong ) 한국복합재료학회 2014 Composites research Vol.27 No.2
섬유강화복합재료는 비강도와 비강성이 뛰어나 여러 분야에 걸쳐 사용량이 증가하고 있으며 자전거와 같은 스포츠 용품에도 사용량이 점점 증가하고 있다. 복합재료는 다양한 형상의 구조부품으로 만들어져 사용되고 있다. 특히 자전거 프레임의 일부에는 사각형 복합재 튜브 형태로 제작되어 사용되고 있으나 이에 관한 연구는 많지 않다. 사각 복합재 튜브의 경우에 모서리에 적절한 라운드 값을 주어 굽힘과 비틀림에 견디도록 설계된다. 본 연구에서는 모서리의 곡률반경이 R5, R10, R15인 세 개의 그룹에 가로-세로 1:1, 1:1.5, 1:2의 형상비를 갖는 아홉 종류의 사각 복합재 튜브를 제작하였다. 탄소섬유강화복합재료가 튜브제작에 사용되었으며 단면적은 모두 같도록 설계되었다. [0/90/±45]s으로 적층하여 제작한 사각 복합재 튜브에 굽힘과 비틀림 하중을 가하여 실험평가를 수행하였다. 실험결과 사각 복합재 튜브의 R 값과 형상비에 따라서 굽힘 및 비틀림 특성이 크게 다름을 알 수 있었다. Fiber reinforced composite materials have outstanding specific strength and specific stiffness. So the use of composite materials increases in various kinds of industrial fields including sports goods such as bicycles. Composite materials are used to make structural parts with various kinds of shapes. Specially, rectangular composite tubes are used to make a few of composite bicycle frames, but there has been a few of research on this issue. Rectangular composite tubes are designed to have appropriate radius of curvature and endure bending and torsional loads. In this research, nine kinds of rectangular composite tubes having aspect ratios 1:1, 1:1.5, 1:2 and radius of curvatures R5, R10, R15 were fabricated. The carbon fiber reinforced composite material was used to make tubes having same cross sectional areas. The stacking sequence of tubes is [0/90/±45]s. Experimental evaluation was accomplished to apply bending and torsional load to the tubes. Experimental results show that bending and torsional characteristics depend on radius of curvature and aspect ratio of rectangular composite tubes.
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P형 슈미트햄머에 의한 초기 압축강도 추정에 관한 연구
이용성 ( Lee¸ Yong Sung ),김기정 ( Kim¸ Ki-jeong ),이백수 ( Li¸ Bai-shou ),윤기원 ( Yoon¸ Gi-won ),한천구 ( Han¸ Cheon-goo ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.7 No.2
This study is intended to investigate the relationship between the rebound value of P type schmidt hammer and compressive strength at early age(until lday), synthesizing the studies on estimation of compressive strength by P type schmidt hammerby this time for confirming compressive strength of 5MPa at which side form can be removed. Regression formula between rebound value of P type schmidt hammer and compressive strength is shown as K= 0.00131 e<sup>2.582ln(X)</sup> and correlativity is favorable (coefficient of correlation 0.895). After analyzing the regression line as confidence coeffient(0.05) by estimate analysis, the allowance limit of y versus x is obtained. Rebound value of P type schmidt hammer, which compressive strength is more than 5MPa, shows 29, based on the lower limit of allowance limit. Therefore, if rebound value of P type schmidt hammer is more than 29, it is thought that compressive strength of concrete exceeds 5MPa under the condition of normal ready mixed concrete.
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플립칩의 반복 굽힘 시험 시 파손 특성에 관한 실험적 연구
이용성(Yong-Sung Lee),정종설(Jong-Seol Jeong),김홍석(Hong-Seok Kim),신기훈(Ki-Hoon Shin) 한국생산제조학회 2009 한국생산제조학회지 Vol.18 No.4
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.
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