• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.577-585
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• 2009

A 9-node degenerated shell finite element(FE), which has been developed for assessment of ultimate pressure capacity and nonlinear analysis for nuclear containment building is described in this paper. Reissner-Midnlin(RM) assumptions are adopted to develop the shell FE so that transverse shear deformation effects is considered. Material model for concrete prior to cracking is constructed based on the equivalent stress-equivalent strain relationship. Tension stiffening model, shear transfer mechanism and compressive strength reduction model are used to model the material behavior of concrete after cracking. Niwa and Aoyagi-Yamada failure criteria have been adapted to find initial cracking point in compression-tension and tension-tension region, respectively. Finally, the performance of the developed program is tested and demonstrated with several examples. From the numerical tests, the present results show a good agreement with experimental data or other numerical results.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.795-801
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• 2021

The designed drone-based unmanned remote radiation detection module was developed according to the needs of the nuclear power plant decommissioning workshop. Using the Geiger-Mueller tube sensitive to low-level radiation measurement, It was manufactured to measure the amount of radiation leaking into and out of the containment vessel. The drone-based radiation detection module weighs less than 200g, It can be operated inside and outside the containment vessel of a nuclear power plant. To check the performance of the designed equipment, a performance evaluation test was conducted with reference to the international standard (IEC-60864). The stability of the radiation detection module designed to meet the needs of the field the statistical rate of change by repeated measurements in the rate of change experiment to evaluate the measurement accuracy was ±4.6%. The accuracy ±7.3% in the linearity experiment to evaluate the dose rate dependence, the linear The figure satisfies the international performance evaluation standard of ±3.5%. The radiation detection module developed in this study is a customized equipment for a nuclear power plant dismantling workshop. It will be helpful for accurate measurement of space dose rate and safety management of radiation worksites in sites with a lot of radiation dust.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.279-285
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• 1997

본 연구에서는 나선형과 판형의 핀을 가진 원자력 발전소용 직교류 핀-관 열교환기의 열량을 ARI Standard-410에 따라 실험적으로 측정하여 풍속과 냉수속에 따른 열저항 및 압력 손실을 도출하는 것을 목적으로 하였으며, 이러한 시도를 통해서 실제 열교환기의 성능 평가시 필요한 기술적 자료를 축적하고자 하였다. 실험에서는 나선형 6fin/in, 8fin/1n, 10fin/in 열교환기와 판형 8fin/in 열교환기를 사용하였으며, 풍속을 0.486m/s와 2.214m/s로, 수속을 1m/s～4m/s로 하여 실험을 행하였다. 실험 결과를 통하여, 원자력 발전소의 격납 용기내의 공기조화를 위하여 사용되어 지는 열교환기의 성능 평가 방법 및 실증 능력을 확보하였으며, 풍속 증가에 따라 총괄 열전달 계수는 전체적으로 비례 증가하는 경향을 보였다. 판형이 나선형 보다 열전달 계수가 작게 나타났으며, 나선형 열교환기의 경우 fin수에 따른 변화는 크지 않았으나, 열전달 면적을 고려한 경우에는 나선형 10fin/in 열교환기가 가장 뛰어난 열교환 성능을 발휘함을 알 수 있었다. 또한, 공기측의 압력 손실은 전체적으로 전연 풍속 증가에 따라서 속도 제곱에 비례하여 증가하는 경향을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.807-810
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• 2014

로봇 시스템의 제어 및 이를 이용한 환경 인식에는 많은 전자 광학 소자들이 사용되고 있다. 로봇 제어회로에 사용되고 있는 Si CMOS 공정의 CPU, ASIC, FPGA 소자는 고 선량의 감마선에 취약하다. 환경정보 수집용으로 로봇에 탑재되는 CMOS/CCD 카메라의 관측영상에는 고선량 감마선으로 인한 speckle (백색잡음, white noise) 들이 나타나며, 이들이 카메라의 관측성능을 저하시킨다. 후쿠시마 원자력발전소 사고와 같이 원자력시설에서 제어불능의 심각한 사고가 발생되면 고선량 감마선이 방출된다. 이러한 고선량 감마선방출은 사람에 의한 사고수습을 불가능하게 하며, 사고 수습을 위해서는 로봇의 활용이 불가피하다. 그러나, 방출되는 고선량 감마선의 세기(선량율)가 지나치게 높을 경우, 로봇 전자회로가 장애를 일으키기 때문에 로봇의 적절한 임무수행이 가능한 감마선 세기에 대한 고려가 필요하다. 본 논문에서는 고선량 감마선 환경하에서의 로봇 탑재 CCD/CMOS 카메라의 관측 성능을 고려하여 100 Gy/h 를 감마선 선량율 제한조건으로 설정한다. 그리고, 재 가동 승인심사를 받기 위해 일본의 원전 운영자들이 제시한 PWR (가압경수로) 원전의 중대사고 대책 적합성 평가문서에 나타난 노심용융개시 시점의 원자로 격납건물내 감마선 선량율 추이 계산결과를 활용하여 로봇의 대응시간을 계산하였다. 문서 (PDF) 에 표현된 감마선 선량율 추이 그래프를 영상 판독하여, 격납건물내 감마선 선량율이 100 Gy/h 제한조건에 도달하는 시간을 계산하였다. 이를 로봇의 대응시간으로 설정한다.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.42-50
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• 2015

To evaluate the heat removal capability of a condenser tube in the PCCS of an advanced nuclear power plant, a steam condensation experiment in the presence of noncondensable gas on a vertical tube is performed. The average heat transfer coefficient is measured on a vertical tube of 40 mm in O.D. and 1.0 m in length. The experiments covers the pressures of 2-4 bar, and the mass fraction of air ranges from 0.1 up to 0.7. From the experimental results, the effects of the total pressure and the concentration of air on the condensation heat transfer coefficient are investigated. The measured data are compared with the predictions by Uchida's and Tagami's correlations, and it is revealed that these models underestimate the condensation heat transfer coefficient of the steam-air mixture.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.46-52
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• 2019

This work proposes a noncontact ultrasonic transducer for detecting wall-thinning of containment liner plates of nuclear power plants by measuring their thickness without physical contact. Because the containment liner plate is designed to prevent atmospheric leakage of radioactive substances under severe nuclear accident, its wall-thinning inspection is important for safety of nuclear power plants. Wall-thinning investigation of containment liner plates have been carried out by measuring their thickness with contact-type ultrasonic thickness gauge by inspectors and needs a lot of time and cost. As an alternative, an electromagnetic acoustic transducer measuring precisely thickness of containment liner plates without any physical contact or couplant was suggested in this research. A transducer generating and measuring shear ultrasonic waves in thickness direction was designed and wave field produced by the transducer was analyzed to verify the design. The working performance of the suggested transducer was tested with carbon steel plate specimens with various thicknesses. The test result shows that the proposed transducer can measure thickness of the specimens precisely without any couplant and implies that swift scanning of wall-thinning of containment liner plates will be possible with the proposed transducer.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.673-683
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• 2016

In recent years, frequent terror or military attack by explosion, impact, fire accidents have occurred. Particularly, World Trade Center collapse and US Department of Defense Pentagon attack on Sept. 11 of 2001. Also, nuclear power plant incident on Mar. 11 of 2011. These attacks and incidents were raised public concerns and anxiety of potential terrorist attacks on major infrastructures and structures. Therefore, the extreme loading researches were performed of prestressed concrete (PSC) member, which widely used for nuclear containment vessel and gas tank. In this paper, to evaluate the blast resistance capacity and its protective performance of bi-directional unbonded prestressed concrete member, blast tests were carried out on $1,400{\times}1,000{\times}300mm$ for reinforced concrete (RC), prestressed concrete without rebar (PSC), prestressed concrete with rebar (PSRC) specimens. The applied blast load was generated by the detonation of 55 lbs ANFO explosive charge at 1.0 m standoff distance. The data acquisitions not only included blast waves of incident pressure, reflected pressure, and impulse, but also included displacement, acceleration, and strains at steel, concrete, PS tendon. The results can be used as basic research references for related research areas, which include protective design and blast simulation under blast loading.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.57-64
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• 2012

Since a seismic exceeding design load can result in exposing radioactive material during disposal process of radioactive wastes, the repository should be designed with enough seismic margin. In this paper, a seismic fragility analysis was performed to evaluate the seismic capacity of surface facility structures. According to the analysis results, since inspection & store facility and radioactive waste facility have a rectangle geometry, the seismic capacity was differently presented about 23%~43% according to the axis of structures. The HCLPF capacity of inspection & store facility and radioactive waste facility was 0.52g and 0.93g, respectively. And it was observed that seismic capacity of radioactive waste facility was similar to that of a containment for nuclear power plants.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.695-703
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• 2012

Recently, major infrastructure such as bridges, tunnels, PCCVs (Prestressed Concrete Containment Vessel), and gas tanks are Prestressed Concrete (PSC) structure types, which improve their safety by using confining effect from prestressing. Generally, concrete is known to be an outstanding fire resistant construction material. Because of this reason, researches related to extreme fire loaded PSC member behaviors are not often conducted even though PSC behavior under extreme fire loading is significantly different than that of ordinary reinforced concrete (RC) behavior. Therefore, in this study, RABT fire loading tests were performed on bi-directionally prestressed concrete panels with $1000{\times}1400{\times}300mm$ dimensions. The prestressed specimens were applied with 430 kN prestressing (PS) force using unbonded PS thread bars. Also, residual strength structural tests of fire tested PSC and ordinary RC structures were performed for comparison. The study results showed that PSC behavior under fire loading is significantly different than that of RC behavior.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.147-161
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• 2017

Generally, significant amount of reinforcements are used in nuclear power plant structures and it may cause several potential problems during the construction. In particular, it is more difficult to pour concrete into structural member joint area than other areas because of the significant congestion of the joint area due to a lot of hooked bars, embedded materials, and other reinforcements. The purpose of this study is to solve these problems due to the reinforcement congestion by using the high-strength(ASTM A615 Gr.80) headed deformed bars of large-sized diameter(43 mm & 57 mm) in nuclear power plant structures as a alternative of standard hooked bars. In order to use headed deformed bars effectively, It is necessary to find the method how to relax limits on their use while maintaining or improving the anchorage capacity. Therefore, this study will analyze the results of tests planned to evaluate the influence of the restricted variables, such as bar size, yield strength, clear cover thickness.