• Nuclear Engineering and Technology
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• 제41권5호
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• pp.561-574
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• 2009

First ex-vessel core catcher has been applied to the practical design of NPPs with VVER-1000 reactors built in China (Tyanvan) and India (Kudankulam) for severe accident management (SAM) and mitigation of SA consequences. The paper presents the concept and basic design of this crucible-type core catcher as well as an evaluation of its efficiency. The important role of oxidic sacrificial material is discussed. Insight into the behaviour of the molten pool, which forms in the catcher after core relocation from the reactor vessel, is provided. It is shown that heat loads on the water-cooled vessel walls are kept within acceptable limits and that the necessary margins for departure from nucleate boiling (DNB) and of vessel failure caused by thermo-mechanical stress are satisfactorily provided for.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1989년도 가을 학술발표회 논문집
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• pp.77-82
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• 1989

In this paper an experimental approach of the relocation plastic hinging zones of nine reinforced concrete exterior beam-column subassemblages under cyclic loads was tried. The main parameters of the testing program were location of the plastic hinge, difference of the special reinforcement, inclined or intermediate layers of longitudinal reinforcement, applied maximum shear stress. The conclusions presented herein are based on the limited texts conducted. Inclined or intermediate layers of longitudinal reinforcement and extra top and bottom steel in the beam over a specific legnth can be used to move the beam plastic hinging zone away from the column face. But, for the use of intermediate layers of longitudinal reinforcement, sheat reinforcement detail need further investigation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.124-127
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• 2002

This paper presents a 3D shape optimization algorithm for electromagnetic devices using the design sensitivity analysis with finite element method. The structural deformation analysis based on the deformation theory of the elastic body under stress is used for mesh renewing. The design sensitivity and adjoint variable formulae are derived for the 3D nonlinear finite element method with edge element. The proposed algorithm is applied to the shape optimization of 3D electromagnet to get a uniform flux density at the air gap.

• 한국산학기술학회논문지
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• 제15권7호
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• pp.4184-4190
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• 2014

본 연구의 목적은 요양시설 입소노인의 일반적 특성에 따른 스트레스와 생활행동지수를 파악하고자 한다. 연구대상은 서울시 N구에 거주하는 입소노인과 강원도 횡성군 S면 거주하는 입소노인 110명 대상으로 2013년 5월 1일부터 9월30일까지 설문조사를 실시하였다. 자료 분석은 SPSS/WIN 18.0 프로그램을 이용하여 t-test, 상관분석, 다중회귀분석방법 등을 실시하였고, 실증분석은 유의수준 5%에서 검증하였다. 분석결과는 첫째, 입소 증후군은 일상적 스트레스의 가족왕래부족 스트레스와 정의 상관이 있었다. 둘째, 우울증상은 일상적 스트레스의 개인시공간부족, 가족왕래부족 스트레스와 정의 상관이 있었다. 셋째, 체중조절은 일상적 스트레스의 개인시공간부족 스트레스와만 정의 상관이 있었으며, 영양결핍증상은 일상적 스트레스의 가족왕래부족 스트레스와만 정의 상관이 있었다. 본 연구의 시사점은 입소노인의 일반적 특성에 따른 스트레스와 생활행동지수 정책의 기초자료가 될 것으로 사료된다.

• Earthquakes and Structures
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• 제8권5호
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• pp.1017-1038
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• 2015

This paper presents a strengthening method that involves the use of ferrocement jackets and chamfers to relocate plastic hinge for non-seismically designed reinforced concrete exterior beam-column joints. An experimental study was conducted to assess the effectiveness of the proposed strengthening method. Four half-scale beam-column joints, including one control specimen and three strengthened specimens, were prepared and tested under quasi-static cyclic loading. Strengthening schemes include ferrocement jackets with or without skeleton reinforcements and one or two chamfers. Experimental results have indicated that the proposed strengthening method is effective to move plastic hinge from the joint to the beam and enhance seismic performance of beam-column joints. Shear stress and distortion within the joint region are also reduced significantly in strengthened specimens. Skeleton reinforcements in ferrocement provide limited improvement, except on crack control. Specimen strengthened by ferrocement jackets with one chamfer exhibits slight decrease in peak strength and energy dissipation but with increase in ductility as compared with that of two chamfers. Finally, a method for estimating moment capacity at beam-column interface for strengthened specimen is developed. The proposed method gives reasonable prediction and can ensure formation of plastic hinge at predetermined location in the beam.

• 한국시스템다이내믹스연구
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• 제4권1호
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• pp.69-91
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• 2003

Using qualitative methods hinged on urban dynamics models, the paper addresses major issues concerned with new administrative capital construction. It tries to summarize the existing debates on new administrative capital construction and reinterpret diverse interacting factors in terms of reinforcing or balancing feedback structure. The paper suggests that understanding up on the dynamic mechanism imbedded in circular causal loop diagrams is the key to set up appropriate proposals and action plans for the new administrative capital, as they would reveal complicated linkages between the Capital Region and the rest, in addition to the urban dynamic of new administrative capital. In the same context, the paper can confirm similar features reflected in the relocation of capital functions at Canberra, Australia and Berlin, Germany. It has paid special attention to the fact that both Australian and German governments altogether stress the positive feedback loops as they have overcome unprecedented political confrontation among rival cities: Basically, they have encouraged gives-and-takes among major stake-holders. These research findings indicate that the future of new administrative capital construction depends on consensus buildings that can accommodate socio-economic and territorial changes between pros and cons. Although further researches and validations are needed, the system approach presented in this paper could assist Korean decision-makers in developing robust and responsive policy initiatives under uncertainties.

• Nuclear Engineering and Technology
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• 제47권3호
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• pp.351-361
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• 2015

External reactor vessel cooling (ERVC) for in-vessel retention (IVR) has been considered one of the most useful strategies to mitigate severe accidents. However, reliability of this common idea is weakened because many studies were focused on critical heat flux whereas there were diverse uncertainties in structural behaviors as well as thermal-hydraulic phenomena. In the present study, several key factors related to molten corium behaviors and thermal characteristics were examined under multi-layered corium formation conditions. Thereafter, systematic finite element analyses and subsequent damage evaluation with varying parameters were performed on a representative reactor pressure vessel (RPV) to figure out the possibility of high temperature induced failures. From the sensitivity analyses, it was proven that the reactor cavity should be flooded up to the top of the metal layer at least for successful accomplishment of the IVR-ERVC strategy. The thermal flux due to corium formation and the relocation time were also identified as crucial parameters. Moreover, three-layered corium formation conditions led to higher maximum von Mises stress values and consequently shorter creep rupture times as well as higher damage factors of the RPV than those obtained from two-layered conditions.

• 기본간호학회지
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• 제16권1호
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• pp.92-102
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• 2009

Purpose: Relocation stress is a common phenomenon in patients discharged from an intensive care unit(ICU) to a ward. Therefore, nurses need to be aware of the problems that can arise during the transfer process. The aim of this study was to identify nurses' experiences in transferring critically ill patients from the ICU to a ward. Method: Focus group interviews were done with 13 nurses from wards and ICU, which participated in receiving and sending of ICU patients. The debriefing notes and field notes were analyzed using the consistent comparative data analysis method. Result: Seven major categories were identified in the analysis of the data. These were 'mixed feeling about transfer', 'lack of transfer readiness', 'increase in family burden', 'uncertainty with unfamiliar environment', 'difficulty in decision making', 'difference of perception of the relationships between patients and health care providers', 'need for continuity of nursing care'. Conclusion: Transferring out of the critical care area should be presented to the patient and family as a positive step in the recovery process. However, a more universal method of passing information from nurse to nurse is needed to assist in a smooth transition.

• 임상간호연구
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• 제15권3호
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• pp.143-155
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• 2009

Purpose: This study was conducted to develop and evaluate the collaborate transitional care program for improving continuity of care in patients transferred to general wards from ICUs. Methods: 18 years and older who were hospitalized in adult intensive care units at A university affiliated medical center was recruited for the study. The experimental group for patients transferred from an ICU consisted of 33 patients and family caregivers; 34 patients and family caregivers for the control group. This study was utilized a quasi-experimental research design. The collaborative transitional care program was administered in transfer process. Data were collected two times by interviews, medical records, and telephone using questionnaires. Results: There were statistically significant differences between the two groups on relocation stress (p<.001), perceived health status (p<.001), satisfaction of caring (p=.011), physical domain (p=.022) and mental domain (p<.001) of the QOL. There were significant differences between the families of the two groups on burden (p<.001) and satisfaction of caring (p<.001). Conclusion: The collaborative transitional care programs administered in transfer process to general wards from an ICU have positive effects on patients and families' intrinsic and extrinsic factors. This program will be able to be utilized in clinical fields to improve continuity of care for patients and families between ICUs and general wards.

• 대한토목학회논문집
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• 제26권3C호
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• pp.201-207
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• 2006

유효응력의 산정을 위해 간극수압의 측정이 필수인 지반공학 분야의 실험에서는 멤브레인을 사용하여 구속압과 간극수압의 계측을 실시하지만 구속압의 변화 등에 의해 멤브레인이 공시체 쪽으로 관입하는 현상이 발생하여 체적변형률과 유효응력의 계측치에는 오차가 포함되게 된다. 본 연구에서는 중공비틀림 전단시험장치를 사용하여 등방제하과정과 반복전단과정 및 액상화 후의 재압밀 과정에 있어서의 멤브레인 관입량 및 관입 보정식에 대한 고찰을 실시하였다. 실험 결과, 반복전단에 의해 모래의 유효응력이 20kPa 이하의 낮은 유효응력 조건에서는 보정식에 의한 멤브레인 보정량이 과대평가 되고 있음을 알 수 있으며, 이러한 보정식의 한계는 유효응력이 0에 가까워질 수록 보정량이 급격히 증가하는 것이 원인이다. 본 연구에서는 이러한 점을 감안하여 보정량의 급증을 방지하기 위한 상수의 도입에 대해서도 검토하였다. 이와 더불어 초기 상대밀도가 높거나 액상화 후의 입자 재배열 등의 밀도 변화가 일어나는 경우에도 보정식의 적용에 대한 신중한 검토가 필요하다는 점도 확인하였다.