• 설비공학논문집
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• 제19권4호
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• pp.307-312
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• 2007

This study was performed to evaluate sleep efficiencies and conditions for comfortable sleep based on the analysis of sleep efficiency and MST under four thermals conditions ($22^{\circ}C,\;24^{\circ}C,\;26^{\circ}C,\;30^{\circ}C$). Five female subjects who have similar life cycle and sleep patterns were participated for the sleep experiment. Their age was from 20 to 22 years old. They were healthy, and had regular sleep with consistent bed and wakeup time. It was checked whether they had a good sleep before the night of experiment. Experiments were performed in an environmental chamber using thermo-hygrostat. The physiological signal (EEG) for sleep stage were obtained from C3-A2 and C4-Al electrode sites. Sleep stages were classified, then SWS latency and SWS/TST were calculated for the evaluation for sleep efficiencies on thermal conditions. As results, mean skin temperature for comfort sleeping was $34.5{\sim}35.4^{\circ}C$. Considering sleep efficiency and mean skin temperature, indoor room temperature of upper limit was $28.1^{\circ}C$.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.773-780
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• 2012

The article presented is concerned with an evaluation of the corrosion behavior of SA-508 low alloy steel (LAS) and Type 309L stainless steel (SS) cladding of a reactor pressure vessel under the simulated primary water chemistry of a pressurized water reactor (PWR). The uniform corrosion and galvanic corrosion rates of SA-508 LAS and Type 309L SS were measured in three different control conditions: power operation, shutdown, and power operation followed by shutdown. In all conditions, the dissimilar metal coupling of SA-508 LAS and Type 309L SS exhibited higher corrosion rates than the SA-508 base metal itself due to severe galvanic corrosion near the cladding interface, while the corrosion of Type 309L in the primary water environment was minimal. The galvanic corrosion rate of the SA-508 LAS and Type 309L SS couple measured under the simulated power operation condition was much lower than that measured in the simulated shutdown condition due to the formation of magnetite on the metal surface in a reducing environment. Based on the experimental results, the corrosion rate of SA-508 LAS clad with Type 309L SS was estimated as a function of operating cycle simulated for a typical PWR.

• 한국기계가공학회지
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• 제17권4호
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• pp.150-159
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• 2018

The present research deals with a finite element analysis and fatigue evaluation of a steam separator of a high-pressure evaporator for the Heat Recovery Steam Generator (HRSG). The fatigue during the expected life of the HRSG was evaluated according to the ASME Boiler and Pressure Vessel Code Section VIII Division 2 (ASME Code). First, based on the eight transient operating conditions prescribed for the HRSG, temperature distribution of the steam separator was analyzed by a transient thermal analysis. Results of the thermal analysis were used as a thermal load for the structural analysis and used to determine the mean cycle temperature. Next, a structural analysis for the transient conditions was carried out with the thermal load, steam pressure, and nozzle load. The maximum stress location was found to be the riser nozzle bore, and hence fatigue was evaluated at that location, as per ASME Code. As a result, the cumulative usage factor was calculated as 0.00072 (much less than 1). In conclusion, the steam separator was found to be safe from fatigue failure during the expected life.

• 한국CDE학회논문집
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• 제14권3호
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• pp.186-196
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• 2009

Mass customization (MC) is a business practice that aims to provide customers with customized products and services at near mass production efficiency. To achieve the aim, a number of methods to implementing MC are proposed. However, most of them require changes in entire process of the company, which make companies hesitate to implement MC even if it is essential to survive. In this paper, we proposed alternatives to partially implement MC for quick adaptation of MC. The base line assumption is not to change the production lines. The pros and cons of alternatives are given by qualitative and quantitative evaluation. Especially, by giving radar chart analysis of the quantitative measures, we give insight on the changes in the business performance measures, such as time to market and cost. Proposed alternatives are based on sub-processes such as purchasing raw materials, production process changes and packaging for efficient logistics. In this way, companies are able to provide customized products with small changing of the current manufacturing system. The process and benefit of the proposed strategy is verified by real world cases of a Korean health food company.

• KIEAE Journal
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• 제12권6호
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• pp.39-47
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• 2012

Recently, the green building and energy connection system are establishing. But, National certification system for environment-Friendly Buildings is indicated hangup about energy efficiency of building. Commissioning, energy conservation, renewable energy, carbon dioxide emissions, it is determined that the energy associated with LEED and GBCC four items of the comparative analysis showed the following results. First, on the practical performance of the system after the completion of commissioning of the energy associated with the system completed until after the final performance for secure operation from the planning stage to verify and document systematically how to perform, but the domestic review and verification is incomplete. Second, the use of energy-saving and renewable energy is directly related to the energy consumption of the building, but GBCC the strengthening of standards on how to evaluate it is deemed necessary. Finally, the evaluation of the reduction of carbon dioxide emissions, LEED Unlike GBCC the life-cycle of the system without considering the global warming index only because a substantial step in the operating efficiency can not be assessed. Based on this study GBCC energy savings through efficiency to actively carry out research through a systematic analysis of the basic guidelines to proceed.

• 대한교통학회지
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• 제26권4호
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• pp.161-172
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• 2008

국토해양부는 신호교차로 서비스수준 분석에 도로용량편람이 제시하는 방법의 적용을 장려하고 있으며 실시간신호제어교차로는 지능형교통체계 구축사업으로 그 숫자가 현장에서 꾸준히 증가하고 있다. 도로용량편람은 정주기식 신호교차로 서비스수준 분석방법에 국한하여 제시하고 있어 현장 실무자들은 실시간신호제어교차로 서비스수준 분석에 어려움을 경험하고 있다. 본 연구는 도로용량편람 수준에서 실시간신호제어교차로 서비스수준 분석의 기초가 되는 방법론을 제안하며 향후 추가로 수행되어야 하는 개발방향을 검토한다. 한 개의 신호교차로를 표본으로 세부 요소모형들을 간이 개발하여 검증한 결과 제안된 방법은 실제 현장 자료와 유사한 수준의 서비스 수준을 추정할 수 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1100-1108
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• 2021

Supercritical water has great potential as a coolant for nuclear reactor. Its use will lead to higher thermal efficiency of Rankine cycle. However, in certain conditions heat transfer may get deteriorated which may lead to undesirable high clad surface temperature. It is necessary to estimate the operating conditions in which heat transfer deterioration (HTD) will take place, so as to establish thermal margins for safe reactor operation. In the present work, the heat flux corresponding to onset of HTD for vertically upward flow of supercritical water in a pipe is obtained over a wide range of system parameters, namely pressure, mass flux, and pipe diameter. This is done by performing large number of simulations using an in-house CFD code, which is especially developed and validated for this purpose. The identification of HTD is based on observance of one or more peak/s in the computed wall temperature profile. The existing correlations for predicting the onset of HTD are compared against the results obtained by present simulations as well as available sets of experimental data. It is found that the prediction accuracy of the correlation proposed by Dongliang et al. is best among the existing correlations.

• 한국표면공학회지
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• 제56권1호
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• pp.84-93
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• 2023

The spent nuclear fuel is burned during the planned cycle in the plant and then generates elements such as actinide series, fission products, and plutonium with a long half-life. An 'interim storage' step is needed to manage the high radioactivity and heat emitted by nuclides until permanent-disposal. In the case of Korea, there is no space to dispose of high-level radioactive waste after use, so there is a need for a period of time using interim storage. Therefore, the intensity of neutrons and gamma-ray must be determined to ensure the integrity of spent nuclear fuel during interim storage. In particular, the most important thing in spent nuclear fuel is burnup evaluation, estimation of the source term of neutrons and gamma-ray is regarded as a reference measurement of the burnup evaluation. In this study, an analysis of spent nuclear fuel was conducted by setting up a virtual fuel burnup case based on CE16×16 fuel to check the total amount and spectrum of neutron, gamma radiation produced. The correlation between BU (burnup), IE (enrichment), and CT (cooling time) will be identified through spent nuclear fuel burnup calculation. In addition, the composition of nuclide inventory, actinide and fission products can be identified.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.119-120
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• 2022

As the seriousness of the climate crisis is emphasized, movements to solve it are becoming active. In Korea, efforts to reduce environmental impacts across all industries are being strengthened through the Framework Act on Low Carbon Green Growth. The construction industry predicts the environmental impact of buildings during the entire life cycle, but in the construction process, there is a difference in energy usage depending on the amount of input, and it is difficult to predict the environmental impact if data cannot be collected. Therefore, this study evaluated the environmental impact of energy usage in the apartment construction process as part of the study on predicting and reducing the environmental impact of the construction process of the construction site. To this end, the environmental effects of buildings were set as global warming, resource consumption, and ozone layer effects, and the environmental effects of the actual energy use in the case were evaluated. In addition, based on the evaluation results, the characteristics of the input energy usage were compared and analyzed.

• 방사성폐기물학회지
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• 제21권4호
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• pp.559-570
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• 2023

The aim of this study is to ensure the structural integrity of a canister to be used in a dry storage system currently being developed in Korea. Based on burnup and cooling periods, the canister is designed with 24 bundles of spent nuclear fuel stored inside it. It is a cylindrical structure with a height of 4,890 mm, an internal diameter of 1,708 mm, and an inner length of 4,590 mm. The canister lid is fixed with multiple seals and welds to maintain its confinement boundary to prevent the leakage of radioactive waste. The canister is evaluated under different loads that may be generated under normal, off-normal, and accident conditions, and combinations of these loads are compared against the allowable stress thresholds to assess its structural integrity in accordance with NUREG-2215. The evaluation result shows that the stress intensities applied on the canister under normal, off-normal, and accident conditions are below the allowable stress thresholds, thus confirming its structural integrity.