배관에 존재하는 원주방향 표면균열에 대한 파괴거동 해석 (I) -J-적분 예측식 -

김진수,김윤재,김영진,Kim, Jin-Su,Kim, Yun-Jae,Kim, Yeong-Jin 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.1

This paper provides the fully plastic J solutions for circumferential cracked pipes with inner, semi- elliptical surface cracks, subject to internal pressure and global bending. Solutions are given in the form of two different approaches, the GEF/EPRl approach and the reference stress approach. For the GE/EPRl approach, the plastic influence functions for fully plastic J are tabulated based on extensive 3-D FE calculations using the Ramberg-Osgood (R-O) materials, covering a wide range of pipe and crack geometries. The developed GEf/EPRl-type fully plastic J estimation equations are then re-formulated using the concept of the reference stress approach for wider applications. Based on the FE results, optimized reference load solutions for the definition of the reference stress are found for internal pressure and for global bending. Advantages of the reference stress based approach over the GE/EPRl-type approach are fully discussed. Validation of the proposed reference stress based J estimation equations will be given in Part II, based on 3-D elastic-plastic or elastic creep FE results using typical tensile properties of stainless steels and generalized creep- deformation behaviours.

PTS 사고하에서 J-Q해석법을 이용한 표면균열의 구속효과 고찰

김진수,최재붕,김윤재,김영진,Kim, Jin-Su,Choe, Jae-Bung,Kim, Yun-Jae,Kim, Yeong-Jin 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.1

In recent years, the integrity of reactor Pressure Vessel(RPV) under pressurized thermal shock (PTS) accident has been treated as one of the most critical issues. Under PTS condition, the combination of thermal and mechanical stress by steep temperature gradient and internal pressure causes considerably high tensile stress at the inside of RPV wall. As a result, cracks on inner surface of RPV may experience elastic-plastic behavior which can be characterized by J-integral. In such a case, however, J-integral may possibly lose its vapidity due to the constraint effect. The degree of constraint effect is influenced by the loading mode, crack geometry and material properties. In this paper, in order to investigate the effect of clad thickness and crack geometry on constraint effect, three dimensional finite element analyses were performed for various surface cracks. Total of 27 crack geometries were analyzed and results were presented by a two-parameter characterization based on the J-integral and the f-stress.

구속효과를 고려한 원자로 압력용기 균열선단에서의 응력분포 예측

김진수,최재붕,김영진,Kim, Jin-Su,Choe, Jae-Bung,Kim, Yeong-Jin 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.4

In the process of integrity evaluation for nuclear power plant components, a series of fracture mechanics evaluation on surface cracks in reactor pressure vessel(RPV) must be conducted. These fracture mechanics evaluation are based on stress intensity factor, K. However, under pressurized thermal shock(PTS) conditions, the combination of thermal and mechanical stress by steep temperature gradient and internal pressure causes considerably high tensile stress at the inside of RPV wall. Besides, the internal pressure during the normal operation produces high tensile stress at the RPV wall. As a result, cracks on inner surface of RPVs may experience elastic-plastic behavior which can be explained with J-integral. In such a case, however, J-integral may possibly lose its validity due to constraint effect. In this paper, in order to verify the suitability of J-integral, tow dimensional finite element analyses were applied for various surface cracks. A total of 18 crack geometries were analyzed, and $\Omega$ stresses were obtained by comparing resulting HRR stress distribution with corresponding actual stress distributions. In conclusion, HRR stress fields were found to overestimate the actual crack-tip stress field due to constraint effect.

PBTI에 의한 무접합 및 반전모드 다중게이트 MOSFET의 소자 특성 저하 비교 분석

김진수,홍진우,김혜미,이재기,박종태,Kim, Jin-Su,Hong, Jin-Woo,Kim, Hye-Mi,Lee, Jae-Ki,Park, Jong-Tae 한국정보통신학회 2013 한국정보통신학회논문지 Vol.17 No.1

본 연구에서는 다중게이트 구조인 나노 와이어 n-채널 무접합(junctionless)와 반전모드(inversion mode) 다중게이트 MOSFET(Multiple-Gate MOSFET : MuGFET)의 PBTI에 의한 소자 특성 저하를 비교 분석하였다. PBTI에 의해서 무접합 및 반전모드 소자의 문턱전압이 증가하는 것으로 관측되었으며 무접합 소자의 문턱전압 변화가 반전모드 소자보다 작음을 알 수 있었다. 그러나 소자특성 저하 비율은 반전모드 소자가 무접합 소자보다 큰 것으로 관측되었다. 특성저하 활성화 에너지는 반전모드 소자가 무접합 소자보다 큰 것을 알 수 있었다. PBTI에 의한 소자 특성 저하가 무접합 소자보다 반전모드 소자가 더 심한 것을 분석하기 위하여 3차원 소자 시뮬레이션을 수행하였다. 같은 게이트 전압에서 전자의 농도는 같으나 수직방향의 전계는 반전모드 소자가 무접합 소자보다 큰 것을 알 수 있었다. In this paper, a comparative analysis of PBTI induced device degradation in nanowire n-channel junctionless and inversion mode Multiple-Gate MOSFET(MuGFETs) has been performed. It has been observed that the threshold voltage is increased after PBTI stress and the threshold voltage variation of junctionless device is less significant than that of inversion mode device. However the degradation rate of junctionless device is less significant than that of inversion mode device. The activation energy of the device degradation is larger in inversion mode device than junctionless device. In order to analyze the more significant PBTI induced device degradation in inversion mode device than junctionless device, 3-dimensional device simulation has been performed. The electron concentration in inversion mode device is equal to the one in junctionless device but the electric field in inversion mode device is larger than junctionless device.

C-arm의 Tube 위치에 따른 거리 및 방향별 피폭선량 비교

김진수,우봉철,김성진,이관섭,하동윤,Kim, Jin-Su,Woo, Bong-Cheol,Kim, Sung-Jin,Lee, Kwan-Sup,Ha, Dong-Yoon 대한디지털의료영상학회 2009 대한디지털의료영상학회논문지 Vol.11 No.1

In operation room, the use of the C-arm unit is increasing. So, the radiation dose of the person who work in operation room was even more increased than before. Thus, this study is shown the measurement of expose dose and the way for decrease of the radiation dose by using the C-arm unit. The experiment was performed with the C-arm unit and used a phantom which is similar to tissue of the human body and fluoro-glass dosimeter for dose measurement. The expose dose were measured by the tube position(over tube, under tube) of the C-arm unit, distance(50, 100$\sim$200cm), direction(I, II, III, IV), runtime(1min, 3min), wearing of the apron. The radiation dose was decreased twice and three times at under tube rather than over tube. The I direction was measured 20$\sim$30% more than the others. The biggest expose dose is 50cm from center on distance. The expose dose is decreased to far from center. In case of Wearing of the apron, the radiation dose was decreased 60$\sim$90% by the distance. But there weren't change of the radiation dose by C-arm tube position. In present, by increasing the usage of the C-arm unit, the radiation dose is inevitable. So, this study recommends us to use the under tube of the C-arm unit. Also, Wearing of the apron is required for minimum of the radiation exposure.

전방락킹, 후방락킹 운동 및 MET(Muscle Energy Techniques)를 이용한 Sway-back 자세 환자의 치험 3례

김진수,김종수,김정원,추원정,남항우,김창연,Kim, Jin-Soo,Kim, Jong-Su,Kim, Jung-Won,Choo, Won-Jung,Nam, Hang-Woo,Kim, Chang-Yeon 척추신경추나의학회 2012 척추신경추나의학회지 Vol.7 No.1

Sway-back 자세를 가진 환자 3례에 전방락킹, 후방락킹 운동 및 MET를 이용하여 치료한 결과 Whole spine X-ray(lateral)상의 척추만곡각도 및 NRS score의 호전을 확인하였다. 이에 저자는 본 증례를 보고하는 바이다. Objectives : The purpose of this study is to investigate the clinical application of Rocking forward, Rocking backward Exercise and MET(Muscle Energy Techniques) to three patients who had sway-back posture. Methods : Three patients diagnosed as sway-back posture, not have discogetic pain, were hospitalized Bu-Chun Jaseng hospital of Oriental Medicine about 20 days and they were treated by Rocking forward, Rocking backward Exercise and MET. To measure the outcome of the patients' improvement, we observed the X-ray of Whole spine and Numerical Rating Scale(NRS). Results : After being treated by Rocking forward, Rocking backward Exercise and MET, the patients' posture was significantly improved and the pain was reduced. The X-ray of Whole spine became almost normal and the improvement of patients' in the NRS score was detected. Conclusions : These results suggest that Rocking forward, Rocking backward Exercise and MET were effective treatment on patients who had sway-back posture.

가압열충격 사고시 결함 이상화 방법이 구조물 건전성 평가에 미치는 영향

김진수,최재붕,김영진,박윤원,Kim, Jin-Su,Choe, Jae-Bung,Kim, Yeong-Jin,Park, Yun-Won 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.2

The reactor pressure vessel is usually cladded with stainless steel to prevent corrosion and radiation embrittlement. Number of subclad cracks may be found during an in-service-inspection due to the presence of cladding. It is specified, in ASME Sec. XI, that a subclad crack is characterized as a surface crack when the thickness of the clad is less than 40% of the crack depth. This condition is provided to keep the crack integrity evaluation conservative. In order to refine the fracture assessment procedures for such subclad cracks under a pressurized thermal shock condition, three dimensional finite element analyses are applied for various subclad cracks existing under cladding. A total of 36 crack geometries are analyzed, and the results are compared with those for surface cracks. The resulting stress intensity factors for subclad cracks are 6 to 44% less than those for surface cracks. It is proven that the flaw characterization condition as specified in ASME Sec. XI can be overly conservative for some subclad cracks.

창업보육센터 입주기업 전자상거래 활성화 방안

김진수,장원철,황기태,김대진,황인호,Kim, Jin-Su,Jang, Won-Chul,Hwang, Ki-Tae,Kim, Dae-Jin,Hwang, In-Ho 한국벤처창업학회 2007 벤처창업연구 Vol.2 No.1

This aim of study is to offer three way(the E-commerce operations site, electronic catalog site, the E- commerce function improvement, the off-line E-biz revitalization) for E-commerce revitalization of business incubator center's resident enterprise through interview with business incubator center's resident enterprise, business incubator center's manager and the operation company of the COBIAN as E-commerce site of business incubator center. Solutions presented by business incubator center are considered from various angles to improve law perception in the COBIAN and to exchange contact information among BI companies in the COBIAN. And The solution emphasize an efficiency as well as an absolute investment to present the solutions that are able to do better important function as business incubator center than any other. furthermore, a business incubator center presents solutions for solving problems with small and medium enterprises as well as the COBIAN, which is doing E-commerce operation.

실린더에 존재하는 축방향 표면균열에 대한 공학적 J-적분식 (II) - 최적참조응력에 기초한 방법-

김진수,김윤재,김영진,Kim, Jin-Su,Kim, Yun-Jae,Kim, Young-Jin 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11

This paper provides an reference stress based J estimation equation fur cylinders with finite internal axial surface cracks under internal pressure. In part 1, the J estimation equation based on deformation plasticity using Ramberg-Osgood (R-0) materials is proposed. In this paper, the developed CE/EPRI -type solutions ale then re-formulated based on the reference stress concept. Such a re-formulation provides a simpler equation for J. estimation are then further extended to combined internal pressure and bending. The proposed reference stress based J estimation equation is compared with elastic-plastic 3-D FE results using actual stress-strain data for a Type 304 stainless steel. Good agreement between the FE results and the proposed reference stress based J estimations provides confidence in the use of the proposed method to elastic -plastic fracture mechanics of pressurised piping.

시편두께 및 균열깊이 영향을 고려한 비표준시편의 J 시험법 및 구속효과의 정량화

김진수,조수만,김윤재,김영진,Kim, Jin-Su,Cho, Soo-Man,Kim, Yun-Jae,Kim, Young-Jin 대한기계학회 2003 大韓機械學會論文集A Vol.27 No.9

This paper compiles solutions of plastic $\eta$ factors and crack tip stress triaxialites for standard and nonstandard fracture toughness testing specimens, via detailed three-dimensional (3-D) finite element (FE) analyses. Fracture toughness testing specimens include a middle cracked tension (M(T)) specimen, SE(B), single-edge cracked bar in tension (SE(T)) and C(T) specimen. The ligament-to-thickness ratio of the specimen is systematically varied. It is found that the use of the CMOD overall provides more robust experimental J estimation than that of the LLD, for all cases considered in the present work. Moreover, the J estimation based on the load-CMOD record is shown to be insensitive to the specimen thickness, and thus can be used for testing specimen with any thickness. The effects of in-plane and out-of-plane constraint on the crack tip stress triaxiality are also quantified, so that when experimental J value is estimated according to the procedure recommended in this paper, the corresponding crack tip stress triaxiality can be estimated. Moreover, it is found that the out-of-plane constraint effect is related to the in-plane constraint effect.