• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.699-706
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• 1998

한국원자력연구소에서는 원자력중장기연구의 일환으로 한국형 표준원전을 모의하는 종합열수력실증실험을 계획하고 있으며, 현재 실험장치에 대한 척도해석(Scaling Analysis), 예비해석(Scoping Analysis) 및 개념설계를 수행하고 있다. 본 논문에서는 영광 3/4호기를 대상으로 척도해석을 통하여 실험장치를 개념설계하고, 저온관 6인치 소형냉각재 상실사고에 대하여 예비해석을 수행한 결과를 보여준다. 개념설계된 실험장치는 높이비가 참조원자로와 동일하고, 체적비가 1/200이다. 실험장치의 개념설계는 이상유동에 대한 3단계 척도법을 적용하였으며, 개념설계의 타당성을 입증하기 위해 RELAP5/MOD3.1 코드를 사용하여 정상상태 및 저온관 6인치 소형냉각재 상실사고시 계통의 거동을 예비 계산하였다. 실험장치에 대한 예비해석결과 사고 거동이 참조원자로와 잘 일치하는 것으로 나타났다. 또한 수평관 및 주냉각재펌프의 척도기준이 사고의 진행과정에 영향을 미치는 중요한 인자로 밝혀졌다

• The KSFM Journal of Fluid Machinery
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• v.19 no.5
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• pp.50-60
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• 2016

A design methodology of the modeled test facility to conserve an injection performance of a passive safety injection system is proposed. This safety injection system is composed of a core makeup tank and a safety injection tank. Individual tanks are connected with pressure balance line on the top side and injection line on the bottom side. It is important to conserve the scaled initial injection flow rate and total injection time since this system can be operated by small gravity head without any active pumps. Differential pressure distribution of the injection line induced by the gravity head is determined by the vertical length and elevation of each tank. However, the total injection time is adjustable by the flow resistance coefficient of the injection line. The scaling methodology for the tank and flow resistance coefficient is suggested. A key point of this test facility design is a scaling analysis for the flow resistance coefficient. The scaling analysis proposed on this paper is based on the volume scaling law with the same vertical length to the prototype and can be extended to a model with a reduced vertical length. A set of passive injection test were performed for the tanks with the same volume and the different length. The test results on the initial flow rate and total injection time showed the almost same injection characteristics and they were in good agreement with the design values.

• Korean Journal of Food Science and Technology
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• v.48 no.4
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• pp.347-353
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• 2016

This study was performed to examine the quality characteristics of the sponge cakes with different contents (2-10% (w/w)) of lemon grass powder (LGP). An increase in LGP content in the cake led to a significant increase in the specific gravity of batter, baking loss rate, redness, hardness, cohesiveness, chewiness, and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of the cakes and a significant decrease in pH, moisture content, specific volume, height, volume and symmetry index, lightness, and yellowness of the cakes. Springness and resilience did not show any difference between the cakes. The consumer acceptance test indicated that the addition of LGP up to 2% did not cause a significant negative effect on the consumer acceptances in all attributes. The sponge cakes with 2% LGP can be recommended for manufacturing bakery.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.1-10
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• 1997

Viscous flow around actual ship is calculated by an use of RANS equations. The propriety of this computing method, usefulness to hull form design and the scale effect which is the effect of viscous flow depending on the scale of ship model are investigated. Reynolds stress is modelled by using k-${\varepsilon}$ turbulence model and the law of wall is applied near the body. Body fitted coordinates are introduced for the treatment of the arbitrary 3-dimensional shape of the ship hull form. The transformed equations in the computational domain are numerically solved by an employment of FVM. In the calculation of pressure, SIMPLE method is adopted and the solution of the discretized equation is obtained by the line-by-line method with the use of TDMA The calculations of two ships, 4410 TEU container carrier and 50,000 DWT class bulk carrier, are performed at model and actual ship scale. The results are compared and discussed with the model test results which are viscous resistance, nominal wake distribution at propeller plane and limiting streamline on the hull surface. They describe the effect of stem form and the scale effect very well. In particular, the calculated nominal wake distribution and limiting streamline are agreed qualitatively with the experiments and the viscous resistance values are estimated within ${\pm}5%$ difference from the resistance tests.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.149-149
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• 2009

본 연구는 고압전력용 중전기기의 몰드절연 및 옥외용 LED의 절연소재는 기기내부에서 발생된 열에너지를 외부로 방사시키는 것이 무엇보다 중요한 것이다. 이런 이유로 고압전력용 전력기기 대부분은 상당한 체적분을 가지고 있기에 초절연을 가지면서 고열전도를 갖는 나노콤포지트를 개발하기위해 에폭시 메트릭스 기반 질화알루미륨의 표면 처리를 실시하여 에폭시 AIN Nanocomposites를 제조하였다. 나노입자의 균질분산은 나노콤포지트 열전도와 초절연성능에 크게 영향을 주게 된다. 이런 소재개발을 위해 에폭시메트릭스에 나노입자의 충진함량을 3wt%로 하였다. 전처리공정을 통하여 에폭시-나노콤포지트에 두 종류의 금속성 coupling agent (Tyzor TE, Tyzor AA-75)를 질화알루미륨 나노입자 표면처리를 건식법으로 실시하였다. 제조된 Epoxy-AIN Nanocomposites의 열적특성과 전기적 특성을 측정하였다. 전기적특성으로 초절연성의 특성인 형상파라미터가 10.93을 그리고 척도파라미터는 176 kV/mm로서 Weibull Plot 누적확률밀도로서(63.2%)의 통계분석된 값을 얻었다. 또한 열적특성 평가를 위해 유리천이온도와 DMA의 온도특성를 조사하였고, 열적.전기적 특성과 나노콤포지트 내부분산(내부 모폴로지:TEM영상)와 연관되어 연구한 결과, 상당히 일치한 결과를 얻을 수 있었다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.259-271
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• 2006

This paper aims to predict the corrosion of a fully cement-grouted rockbolt induced by chloride diffusion in a cement mortar grout. From the viewpoint of the long-term durability, a rockbolt may be deteriorated by chemical components, such as sulphate and chloride, in groundwater. Especially, the steel rod of a rockbolt is corroded mainly by chloride. The rockbolt corrosion results in the volume expansion of a rod and then the cracking of a cement grout. In this study, the chloride diffusion coefficient of a cement mortar grout was used to evaluate the possibility of rockbolt corrosion by chloride, and to predict the long-term durability of a rockbolt. The electric acceleration test method was adopted to measure the chloride diffusion coefficient. In addition, a simple pullout testing system was newly proposed to measure the pullout capacity of a rockbolt more easily in a laboratory condition. From the experiments, it was showed that the chloride could diffuse in the cement grout more easily than in ordinary concrete materials. As a result, it was considered that a rockbolt might be easily corroded in a short term by the diffusion of chemical components with high concentration, although it was fully grouted.