• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.118-123
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• 2004

Cast austenitic stainless steel have been widely used for primary coolant piping in light water reactors. This material is subject to thermal embrittlement at reactor operating temperature. CF-8M and CF-8A cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. Thermal embrittlement results in spinodal decomposition of delta-ferrite leading to decreased fracture toughness. In this study, the specimens were prepared using an accelerated aging method. The measurement of ferrite content, Charpy impact test and J-R test were performed to verify the predicting equation for aged material properties. In case of above 25% ferrite content, predicted result of J-R curve might be non-conservative.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.131-136
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• 2003

CF8M cast austenitic stainless steel is used for several components such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. In this study, three kinds of the aged CF8M specimen were prepared using an artificially simulated aging method. The objective of this study is to summarize the method of estimating ferrite contents, Charpy impact energy and J-R curve, and to evaluate the thermal embrittlement of the CF8M cast austenitic stainless steel piping used in the domestic nuclear power plants.

• 대한기계학회논문집
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• 제19권6호
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• pp.1460-1468
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• 1995

The objective of this paper is to evaluate the material properties of SA106 Gr. C carbon steel and its associated weld manufactured for main steam system of Yonggwang 3,4 nuclear generating stations. A total of 43 tensile and 35 fracture toughness tests were performed and the effects of various parameters such as pipe size, crack plane orientation, test temperature, welding on material properties were discussed. Test results show that the effects of crack plane orientation, test temperature, and welding on fracture toughness were significant while the effects of pipe size, specimen orientation and test temperature on tensile properties were negligible. Especially the dependence of J-R curves on the crack plane orientation appears to be the characteristics of carbon steel.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2022-2032
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• 1999

In recent years, the subject of remaining life assessment has drawn considerable attention in the power generation industry. In power generation systems a variety of structural components, such as steam pipes, turbine rotors, and superheater headers, typically operate at high temperatures and high pressures. Thus a life prediction methodology accounting for fracture and rupture is increasingly needed for these components. For accurate failure assessment, in addition to the single parameter such as K or J-integral used in traditional fracture mechanics, the second parameter like T-stress describing the constraint is needed. The most critical defects in such structures are generally found in the form of semi-elliptical surface cracks in the welded piping-joints. In this work, selecting the structures of surface-cracked plate and straight pipe, we first perform line-spring finite element modeling, and accompanying elastic-plastic finite element analyses. We then present a framework for including constraint effects (T-stress effects) in the R6 failure assessment diagram approach for fracture assessment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.54-59
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• 2004

In this paper probabilistic fracture mechanics(PFM) approach is employed to evaluate the integrity of CANDU Zr-2.5Nb pressure tubes. Modified failure assessment diagram(Jr-FAD), plastic collapse, and critical crack length(CCL) approach are used for evaluating failure probability of the tubes. Jr-FAD was extended from the Kr-FAD because fracture of pressure tubes occurs in brittle manner due to hydrogen embrittlement of material by deuterium fluence. For developing the probabilistic integrity evaluation module, AECL procedures and fracture toughness parameters of EPRI were used.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.96-101
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• 2004

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal embrittlement at the reactor operating temperature. The objective of this study is to summarize the method of estimating ferrite content, Charpy impact energy and J-R curve and to evaluate the thermal embrittlement of the cast austenitic stainless steel piping used in the domestic nuclear power plants. The result of evaluation, two domestic nuclear power plants used CF-8M and CF-8A material has adequate fracture toughness after saturation.

• 전자통신동향분석
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• 제24권5호
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• pp.152-159
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• 2009

세계화에 따른 경쟁의 심화는 국가의 개입여지는 축소됨과 동시에 지방이 경쟁단위로 노출됨에 따라 지역의 역할이 증대된다. 이러한 변화에 따라 지역산업정책의 여건을 분석하고 지역의 수요에 부응하기 위해 노력하는 것은 지역 선도 R&D 연구센터로 발전하고자 하는 대경권연구센터에 있어서 매우 의미있는 작업이 될 것이라 여겨진다. 따라서 최근 지역산업정책에 큰 변화를 가져온 두 가지 흐름인 5+2 광역경제권 선도산업과 첨단의료복합단지 조성사업과 더불어 기존 지역산업정책인 전략산업의 현황을 분석하고 대경권연구센터와 에트리 본원의 역할방향 및 시사하는 바를 논의하고자 한다.

• 전자통신동향분석
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• 제39권2호
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• pp.93-102
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• 2024

As the scale of research and development (R&D) increases, countries and companies are consistently establishing R&D directions to meet strategic goals and market demands as well as roadmaps to increase efficiency through concentration and selection. However, establishing an effective roadmap and discovering promising technologies are challenging under the current numerous technological possibilities and uncertainties. The importance of discovering promising technologies to secure future technological competitiveness is recognized worldwide, and Europe, the United States, and Japan are establishing processes to identify promising future technologies and support related R&D. Methods for discovering promising future technologies can be classified into future social needs analysis, forecasting, surveys, use of expert opinions, and data analysis. We describe the types and limitations of technology roadmaps and investigate the status of domestic and foreign organizations using weak signal search through quantitative data analysis.

• 대한기계학회논문집
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• 제19권6호
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• pp.1451-1459
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• 1995

The objective of this paper is to evaluate the material properties of SA312 TP316 and SA312 TP304 stainless steels and their associated welds manufactured for safety injection system of Yonggwang 3,4 nuclear generating stations. A total of 62 tensile tests and 46 fracture toughness tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, tests were conducted and the effects of various parameters such as pipe size, crack plane orientation, test temperature, welding on material properties were discussed. Test results show that the effect of test temperature on fracture toughness was significant while the effects of pipe size and crack plane orientation on fracture toughness were negligible. Fracture toughness of the weld metal was in general higher than that of the base metal.

• 전자통신동향분석
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• 제27권2호
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• pp.99-108
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• 2012

지난 세기말까지는 통신의 주된 기능이 음성 전달에 머물렀지만 금세기에 들어와서는 동영상을 위시한 다양한 정보들이 생산되고 유통되며 소비되고 있다. 데이터 트래픽은 음성 트래픽을 오래 전에 추월하고도 매년 기세가 꺾일 줄 모르고 기하급수적으로 증가 중이다. 이러한 정보화 시대를 뒷받침하는 여러 요소가 있으나 광전송 기술의 공로도 결코 작은 것이 아니며 앞으로도 누구나 최소한의 비용으로 무한한 정보를 생산하고 유통하며 향유하는데 선도적 역할을 할 것이다. 돌이켜보면 1960년대에 유리로 된 광섬유를 통해 신호를 전송하는 아이디어가 나왔으며 1970년대 말에 광섬유 전송이 실용화 되었다. 그리고 1980년대에 광증폭기 기술이 등장하여 1990년대 후반에 광섬유선로 하나를 여러 신호가 공유하는 WDM(Wavelength Division Multiplexing) 기술이 마침 시작된 트래픽 폭발을 뒷받침하여 빠른 속도로 확산되었다. 이제는 거의 무한대로 여겨지던 광섬유의 대역폭도 아껴 써야 하는 시대가 다가오고 있다. 한편 기존 광전송망의 에너지 소모, 비용, 상면적 등의 확장을 최소화하면서도 계속 증가하는 트래픽을 수용하여야 한다. 본고에서는 최근에 표준화가 이루어져 시장이 열리고 있는 100G급 기술을 중심으로 광전송 기술의 최근 동향을 요약하였다.