• Journal of the Korean Society of Safety
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• v.35 no.1
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• pp.107-115
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• 2020

This paper introduces the first vital area identification (VAI) process for the physical protection of nuclear power plants (NPPs) during low power and shutdown (LPSD) operation. This LPSD VAI is based on the 3rd generation VAI method which very efficiently utilizes probabilistic safety assessment (PSA) event trees (ETs). This LPSD VAI process was implemented to the virtual NPP during LPSD operation in this study. Korea Atomic Energy Research Institute (KAERI) had developed the 2nd generation full power VAI method that utilizes whole internal and external (fire and flooding) PSA results of NPPs during full power operation. In order to minimize the huge burden of the 2nd generation full power VAI method, the 3rd generation full power VAI method was developed, which utilizes ETs and minimal PSA fault trees instead of using the whole PSA fault tree. In the 3rd generation full power VAI method, (1) PSA ETs are analyzed, (2) minimal mitigation systems for avoiding core damage are selected from ETs by calculating system-level target sets and prevention sets, (3) relatively small sabotage fault tree that has the systems in the shortest system-level prevention set is composed, (4) room-level target sets and prevention sets are calculated from this small sabotage fault tree, and (5) the rooms in the shortest prevention set are defined as vital areas that should be protected. Currently, the 3rd generation full power VAI method is being employed for the VAI of Korean NPPs. This study is the first development and application of the 3rd generation VAI method to the LPSD VAI of NPP. For the LPSD VAI, (1) many LPSD ETs are classified into a few representative LPSD ETs based on the functional similarity of accident scenarios, (2) a few representative LPSD ETs are simplified with some VAI rules, and then (3) the 3rd generation VAI is performed as mentioned in the previous paragraph. It is well known that the shortest room-level prevention sets that are calculated by the 2nd and 3rd generation VAI methods are identical.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.55-64
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• 2010

The study has conducted a research on the main shape of domestic multi-family residential buildings. The four arrangements were selected after the research and each of them was analyzed for daylight, view and natural ventilation according to the different pitch of buildings. Based on the results from the analysis, the optimum pitch of buildings for each of the arrangements are as follows. With looking at the outcomes from the analysis on changes in residential environment by the pitch of building buildings in the four arrangements, it was figured out that it would be the best if the distance is more than 1.0H for Case_1. For Case_2, it should be more than 0.9H and for Case_3, it has to be 1.0H or more. Last but not least, it seems to be superb if the distance is more than 0.9H for Case_4.

• KIEAE Journal
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• v.17 no.2
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• pp.5-12
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• 2017

Purpose: Under the purpose of presenting the adequate remodeling period for the improvement of thermal insulation performance of external walls in deteriorated buildings, the change in external wall and residential environment problem(dew condensation) due to aged deterioration after the apartments were constructed in Korea were analyzed. Method: Temperature Difference Ratio Outside(TDRo) and Heat Flow Meter(HFM) were used as measurement methods to evaluate the thermal insulation performance of deteriorated buildings. For TDR evaluation, thermo-graphic camera was used to measure and analyze the surface temperature of external wall. Also, dew condensation evaluation was analyzed using the Temperature Difference Ratio Inside(TDRi). Result: As a result of analyzing thermal performance through TDRo, the first decline point of thermal insulation performance began after 14-16 years have passed since construction was completed, and after 20 years have passed the decline point of thermal insulation performance reappeared. As a result of analyzing U-value with HFM measurement method, the decline rate of external wall's thermal insulation performance is lower than 2% in average at around 5 years after completion, and 8.7% in average at 10-15 years, and over 10.2% in average at 20 years.

• KIEAE Journal
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• v.16 no.1
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• pp.21-28
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• 2016

Purpose: The purpose of this study is to analyze & suggest the variation of energy consumption consequent on thermal insulation performance strengthening from early 2000s when modernization of barracks began until the present targeting a large barracks. Method: To carry out this research, this study surveyed the standard of thermal insulation by year, which is being applied to a barracks by conducting literature search, and selected the standard model for a barracks. Also, this study analyzed energy consumption by year & region by performing simulation(ECO2)of the selected standard model. Result: As a result, it was analyzed that in case of a building which was completed in 2015, the energy consumption for air-conditioning & heating, lighting, and hot water supply over the year 2000 reduced by 11% on the average in central district, 10% on the average in southern district, and 17% on the average in Jeju, respectively.

• KIEAE Journal
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• v.16 no.3
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• pp.57-62
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• 2016

Purpose: A lot of active researches have addressed the impact of a building on global environment, but most of the researches focus on a residential building and a large office building. Hereupon, this study assessed the impact on environment quantitatively through the analysis of input materials targeting a school building. Method:This study calculated embodied energy of input materials suggested in a construction statement on a school building using the input-output analysis. This study finally carried out environmental impact assessment by applying LCIA DB shown in the preceding researches to the calculated embodied energy. Result: The analysis result revealed that the environmental impact per unit area(/$m^2$) at a school building was $4.11E-02PE{\cdot}yr$, among which Construction was found to be $3.59E-02PE{\cdot}yr$, being analyzed to account for about 87% of the total environmental impact. Also, as a result of detailed environmental impact, the impact on global warming among the total environmental impact was analyzed to be high, accounting for about 76%.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.611-618
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• 2008

The development of information society together with information telecommunication's influence on the human society is a ripple effect and getting wider. Among those ripple effects the disaster prevention is in the public eye in the present day. On the way to the ubiquitous society the main techniques to be concerned in ubiquitous sensor networks are the field of damage of storm and flood, safety facilities, traffic safety, industrial safety, energy safety, fire fighting, specific safety of radioactivity escape incident, environmental pollution, sea pollution, mountain and forrest disaster so on. In this paper the USN technique based on the disaster prevention communication technology service and its requirement technology and application are studied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1257-1264
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• 2011

Guided ultrasonic waves propagating over long distances within a short period provide a fast long-range inspection method. However, structures with arbitrary cross-sections, such as rails, have complicated dispersion characteristics that make analysis of the ultrasonic signal difficult. Therefore, an understanding of the characteristics of the propagating waves in rails is important for the creation of a reliable and practical inspection system using guided waves. In particular, it is necessary to investigate the dispersion characteristics of the guided waves. This paper introduces a method for the calculation of the dispersion curves of KS60 rails by adopting a SAFE method, and discusses the possibility of using guided waves as a technique for rail inspection.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.39-43
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• 2005

Toward the practical applications, on operation of conduction-cooled HTS SMES at temperatures well below 77 K should be investigated, in order to take advantage of a greater critical current density of HTS and considerably reduce the size and weight of the system. Recently, research and development concerning application of the conduction-cooled HTS SMES that is easily movement are actively progressing in Korea. Electrical insulation under cryogenic temperature is a key and an important element in the application of this apparatus. However, the behaviors of insulators for cryogenic conditions in air or vacuum are virtually unknown. Therefore, this work focuses on the breakdown and flashover phenomenology of dielectrics exposed in vacuum for temperatures ranging from room temperature to cryogenic temperature. Firstly, we summary the insulation factors of the magnet for HTS SMES. And a surface flashover as well as volume breakdown in air and vacuum has been investigated with two kind insulators. Finally, we will discuss applications for the HTS SMES including aging studies on model coils exposed in vacuum at cryogenic temperature.

• Journal of the Korean Institute of Gas
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• v.20 no.1
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• pp.23-28
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• 2016

"Eco-friendly" automobile has been a symbol of the Low Carbon, Green Growth strategy that Korea government decided to pursue. In line with the recent policy trend, a number of new LPG stations are being constructed. However, communities where mass storage are installed have been suffered from risk of serious accidents. In this work, economic analyses for different installation methods has been performed to prevent accidents in LPG filling station. The review shows that the underground storage is beneficial for the maintenance and the effective land use.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.37-42
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• 2006

In this study, $20Nm^3/hr$ scale compact hydrogen generator which can be apply to the hydrogen station was tested for hydrogen station application. $20Nm^3/hr$ scale compact hydrogen generator was developed by upgrading concept of stacking plate reactor from former $20Nm^3/hr$ scale plate hydrogen generator. concepts for improving system efficiency and performance include such as idea of heat recovery from the exhaust, exhaust duct which is especially design for plate type reactor reinforcement of insulation, enlargement of heat exchange area of reactor, introduction of desulphurizer reactor and PROX rector in a compact design, introduction of back fire protection structure of plate burner and so on, We can learn that final prototype of scale-up $20Nm^3/hr$ scale compact hydrogen generator can be operated steadily in 100% road at which over 94% of methane conversion(S/C=3.75) was obtained. In case of making up the weak point, we expect that it is possible to apply to hydrogen station by way of showing an example.