• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.235-236
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• 2005

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.1988-1997
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• 2005

This study is concerned with structural integrity evaluations for the interference-fit flywheels in reactor coolant pumps (RCPs) of nuclear power plants. Stresses in the flywheel due to the shrinkage loads and centrifugal loads at the RCP normal operation speed, design overspeed and joint-release speed are obtained using the finite element method (FEM), where release of the deformation-controlled stresses as a result of structural interactions during rotation is considered. Fracture mechanics evaluations for a series of cracks assumed to exist in the flywheel are conducted, considering ductile (fatigue) and non-ductile fracture, and stress intensity factors are obtained for the cracks using the finite element alternating method (FEAM). From analysis results, it is found that fatigue crack growth rates calculated are negligible for smaller cracks. Meanwhile, the material resistance to non-ductile fracture in terms of the critical stress intensity factor (K$_{IC}$) and the nil-ductility transition reference temperature (RT$_{NDT}$) are governing factors for larger cracks.

• Nuclear Engineering and Technology
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• 제49권2호
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• pp.426-433
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• 2017

This paper describes the development process, the innovative techniques used and insights gained from the latest integrated, full scope, multistate Level 2 PSA analysis conducted at the Leibstadt Nuclear Power Plant (KKL), Switzerland. KKL is a modern single-unit General Electric Boiling Water Reactor (BWR/6) with Mark III Containment, and a power output of $3600MW_{th}/1200MW_e$, the highest among the five operating reactors in Switzerland. A Level 2 Probabilistic Safety Assessment (PSA) analyses accident phenomena in nuclear power plants, identifies ways in which radioactive releases from plants can occur and estimates release pathways, magnitude and frequency. This paper attempts to give an overview of the advanced modeling techniques that have been developed and implemented for the recent KKL Level 2 PSA update, with the aim of systematizing the analysis and modeling processes, as well as complying with the relatively prescriptive Swiss requirements for PSA. The analysis provides significant insights into the absolute and relative importances of risk contributors and accident prevention and mitigation measures. Thanks to several newly developed techniques and an integrated approach, the KKL Level 2 PSA report exhibits a high degree of reviewability and maintainability, and transparently highlights the most important risk contributors to Large Early Release Frequency (LERF) with respect to initiating events, components, operator actions or seismic component failure probabilities (fragilities).

• Journal of Advanced Marine Engineering and Technology
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• 제26권4호
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• pp.457-463
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• 2002

The closed cycle diesel engine is used in a closed circuit system which has no air breathing. The working fluid as intake mixture are consisted of oxygen, argon and recirculated exhaust gas in order to obtain underwater or underground power sources. In the present study, the high pressure diesel engine which can be operated by the closed cycle system with high intake pressure for increasing the net power rate is designed. It has been carried out to investigate the combustion characteristics of high pressure diesel engine according to the power rate. The maximum cylinder pressure and heat release rate were investigated. Also, major experimental data such as specific fuel consumption rate, oxygen concentrations, fuel conversion efficiency, polytropic exponent, and IMEP were compared with low pressure diesel engine experimental data.

• 동력기계공학회지
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• 제17권1호
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• pp.71-76
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• 2013

This study is experimentally performed for using the oyster shell as a desiccant in the batch type system. The peltier element(thermoelectric device) is used for absorbing and releasing the adsorption and desorption heat generation. The cooling and heating effects of peltier element exist in this experiment and these effects are generally known phenomena among some references. The increase in electric current induced into peltier element is effectively release the heat generation of adsorption and desorption. Consequently, the non-dimensional adsorption and desorption amount would increase with increase in electric current. However, in the case of adsorption, the increase of induced current into peltier element, the heat of cold side can not release sufficiently. So the heat of hot side of peltier is transferred into the cold side.

• 한국안전학회지
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• 제35권5호
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• pp.22-29
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• 2020

In this study, combustion and smoke release characteristics of a non-class 1E cable for nuclear power plants were investigated according to aging period. The aging was reproduced through an accelerated aging method for interval of 10 years :10, 20, 30 and 40 year, which was applied the Arrhenius equation. The cable was subjected to accelerated aging. In order to understand combustion and smoke release characteristics, the cone calorimeter test was performed according to the standard code of KS F ISO 5660-1. Heat release rate, mass loss rate, average rate of heat emission and smoke production rate were examined through cone calorimeter test. Fire performance index, fire growth index and smoke factor were derived from test results for the comparison of quantitative fire risk. When comparing the fire performance index and the fire growth index, the early fire risk tends to decrease as aging progresses, which might be attributed from the fact that the volatile substances of cables were evaporated. However, when comparing the heat release rate, average rate of heat emission and mass loss rate, which represent the mid and late periods of the fire risk, the values of accelerated aging cables were much higher than those of non-aged cable, which signifies the unstable formation of the char layer resulted in the change in the performance of flame retardants. In addition, the results from the smoke characteristics show that the accelerated aging cables were lager than the non-aged cables in terms of overall fire risk. These results can be used as baseline data when assessing fire risk of cables and establishing fire safety code for nuclear power plants.

• 한국전자통신학회논문지
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• 제16권6호
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• pp.1213-1222
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• 2021

본 연구는 2050 탄소중립 정책으로 에너지신산업 분야 혁신기술개발 일환의 ICT기술에 기반한 디지털화 연구로서 각각의 에너지 설비의 외부 인터페이스와 연동하여 통합관리 할 수 있는 oneM2M 기반 IoT 서버 플랫폼 개발이다. 전력 공기업인 한전은 에너지 IoT 'SPIN(Smart Power IoT Network)' 구축을 통한 한전 e-IoT 표준 규격을 분석하고 oneM2M 및 LWM2M Gateway Platform을 개발한다. oneM2M은 기존 Release1 대신 최근에 발표된 Release2에 대한 규격을 확보 및 분석하여 R2를 기준으로 e-IoT 표준 oneM2M 플랫폼을 개발하고, 또한 한전 e-IoT 표준을 충분하게 구현할 수 있는 e-IoT Gateway 장치 규격을 선정하고 향후 확장성까지 고려한 고성능의 Gateway 장치를 개발하고 관련 시스템을 제안하였다.

• Biomaterials and Biomechanics in Bioengineering
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• 제1권1호
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• pp.13-25
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• 2014

In the current study, a drug-eluting stent coated with biodegradable polymers and sirolimus was developed by using an ultrasonic nanocoater and characterized in aspects of surface smoothness and coating thickness. In addition, in vitro release profiles of sirolimus by changing top coating layer with different biodegradable polymers were investigated. Smooth surfaces with variable thickness could be fabricated by optimizing polymer concentration, flow rate, nozzle-tip distance, gas pressure, various solvents and ultrasonic power. Smooth surface could be generated by using volatile solvents (acetone, chloroform, and methylene chloride) or post-treating with solvent vapor. Coating thickness could be controlled by varying injection volume or polymer concentration, and higher concentration could reduce the coating time while obtaining the same thickness. The thickness measurement was the most effectively performed by a conventional cutting method among three different methods that were investigated in this study. Release profiles of sirolimus were effectively controlled by changing polymers for top layer. PLGA made the release rate 3 times faster than PDLLA and PLLA and all top layers prevented burst release at the initial phase of profiles. Our results will provide useful and informative knowledge for developing drug-eluting stents, especially coated with biodegradable polymers.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2014년도 춘계학술대회
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• pp.260-261
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• 2014

In the present study analysed the physico chemical properties and distribution of heavy metal and also analysed the changes of heavy metal distribution by resuspension and properties of heavy metal release into sea water. From the experimental result showed sediment resuspension plays an important role in the release of heavy metals in coastal environment. Heavy metal release percentage was high in different mixing time of resuspension and different amounts of sediment due to resuspension of particulate matter.

• 방사성폐기물학회지
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• 제20권3호
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• pp.321-338
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• 2022

The transport of radionuclides at oceanic scales can be assessed using a Lagrangian model. In this review an application of such a model to the Atlantic, Indian and Pacific oceans is described. The transport model, which is fed with water currents provided by global ocean circulation models, includes advection by three-dimensional currents, turbulent mixing, radioactive decay and adsorption/release of radionuclides between water and bed sediments. Adsorption/release processes are described by means of a dynamic model based upon kinetic transfer coefficients. A stochastic method is used to solve turbulent mixing, decay and water/sediment interactions. The main results of these oceanic radionuclide transport studies are summarized in this paper. Particularly, the potential leakage of ¹³⁷Cs from dumped nuclear wastes in the north Atlantic region was studied. Furthermore, hypothetical accidents, similar in magnitude to the Fukushima accident, were simulated for nuclear power plants located around the Indian Ocean coastlines. Finally, the transport of radionuclides resulting from the release of stored water, which was used to cool reactors after the Fukushima accident, was analyzed in the Pacific Ocean.