• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.307-312
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• 2015

The sandwich panel is commonly used domestically because it's less costly and easier to handle. But fires have frequently occurred in buildings employing sandwich panels, such as the fires in Eecheon cold storage and in Gwangju Pyungdong industrial zone. Sandwich panels with steel plates on their surface prevent fire water from penetrating to the fire source, which makes it difficult to extinguish a fire in a timely manner. Toxic gas generated from some insulation material leads to serious loss of life and property. This study is intended to develop an extinguishing system for sandwich panels, thereby reducing the fire risk. Fire water and volume were determined in the wake of the study on the structure of a sandwich panel extinguishing system, and improvement and testing of the fire characteristics of the sandwich panel. Based on such study and test, a fire model test was conducted. Consequently, the sandwich panel with extinguishing system was proven to have a reduced fire risk, compared to traditional or fire retardant panels.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.912-917
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• 2010

It was known that oil-filled transformer's life depended on insulating paper which was applied to transformers for insulating of transformer. Therefore when paper was aged, its electrical, mechanical and chemical characteristics were changed. Especially if operating temperature was high, paper was quickly damaged. As cellulose paper which was mainly used for solid insulation of transformers was degraded, the cellulose polymer chains broke down into shorter lengths and gases such as CO, $CO_2$, $CH_4$, $C_2H_4$ and so on were produced from paper. Also by-product known as furan compounds were producted from paper and it were dissolved within insulating oil. In this paper accelerating aging cell was aged during 60 hours at 100, 150, 180 and $200^{\circ}C$, respectively, so evaluating the chemical characteristics of cellulose paper by thermal. An it were performed analysis such as tensile strength(TS), dissolved gas analysis(DGA) and high performance liquid chromatography(HPLC). Also for analyzing of correlation between insulating degradation characteristics, it was performed linear regression method as statistical treatment.

• Journal of the Korean housing association
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• v.27 no.5
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• pp.65-72
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• 2016

The purpose of the study was to investigate defect cases in residential interior design, to identify the state of defects, and to categorize types of defect and disputes. In addition, consumer appraisal to residential interior design service were analyzed. The results of this study could provide fundamental information regarding the defects and claims in residential interior design. First, we did literature review for defect disputes in architectural design and interior design. We identify the definition of defects by building life cycle, by state of construction, by activity, and by design performance. Second, we analysed interior design defects cases reported in Korea Consumer Agency & Ministry of Land, Infrastructure and Transport. A total of 49 cases of defect disputes in residential interior design from 2000 to 2015 were investigated. As a result, many defects appeared during the construction stage. A majority of defects cases fall into insulation, water-proofing/leakage work. In terms of design aspects claim, functional and aesthetic defects were claimed. Third, from Consumer Market Evaluation Indicators, raw data from 500 respondents were investigated for the housing repair and interior design. It is found that information comparability, responsiveness to consumer claim, price, and safety are important factors for consumer satisfaction in interior design.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.148-148
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• 2017

Surface modification is a type of mechanical manipulation skills to achieve extensive aims including corrosion control, exterior appearance, abrasion resistance, electrical insulation and electrical conductivity of substrate materials by generating a protective surface using electrical, physical and chemical treatment on the surface of parts made from metallic materials. Such surface modification includes plating, anodizing, chemical conversion treatment, painting, lining, coating and surface hardening; this study conducted cavitation experiment to assess improvement of durability using anodizing. In order to observe surface characteristics with applied current density, the electrolyte temperature, concentration was maintained at constant condition. To prevent hindrance of stable growth of oxide layer due to local temperature increase during the experiment, stirring was maintained at constant speed. In addition, using galvanostatic method, it was maintained at processing time of 40minutes for 10 to $30mA/cm^2$. The cavitation experiment was carried out with an ultra sonic vibratory apparatus using piezo-electric effect with modified ASTM-G32. The peak-to-peak amplitude was $30{\mu}m$ and the distance between the horn tip and specimen was 1mm. The specimen after the experiment was cleaned in an ultrasonic bath, dried in a vacuum oven for more than 24 hours, and weighed with an electric balance. The surface damage morphology was observed with 3D analysis microscope. As a result of the study, differences were observed surface hardness and anti-cavitation characteristics depending on the development of oxide film with the anodizing process time.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.6
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• pp.45-58
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• 2005

The objective of this study is to the integrated evaluation of the present condition and satisfaction of visitors of rooftop greening area using quantitative and qualitative method. The thirteen green roofs were selected to investigate environmental variables as like building structure, soil, water, atmosphere and climate environment and questionnaire survey for investigate the satisfaction of visitors was conducted. The results of this study are as follows : remove of the hazardous inflow of species, install rain water recycling facility, install outdoor unit of air condition where not to affect plants in green roof, install safety facilities in the case of making resting place, plant variable vegetation and so on. The result of questionnaire survey are that visitors want to make more comfortable resting space. The more bigger the resting space and privacy, the more satisfaction of visitor became high. In conclusion, green roofs implementation should be considered reduction of temperature and delay of runoff, insulation effect and ecological restoration as well as rooftop greening is focused on the development of resting space nowadays.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.6
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• pp.34-44
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• 2005

The objective of this study is to analyze the thermal properties of various green roof type. The experimental districts, have different soil thickness, soil type, the existence of module and the different kinds of vegetation, had installed. A measurement was conducted in Seoul University to investigate the thermal impacts of rooftop greening. The measurement point of temperature were 30, located in soil surface, middle of the soil layer, under the module, hard surface and soffit surface of each experimental district. The experimental investigation lasted from 6th August to 29th August, a total of 24 days. The results showed that green roof can contribute thermal benefits by soil and vegetation and reduce building energy consumption by a role of insulation. It's also better to make soil thickness over 20cm and various vegetation that should be more effective. The district installed only soil also could be effective for reducing the temperature of roof surface. Therefore, the increase of soil thickness and various vegetation could reduce more temperature of roof surface and building energy consumption. Also, it's helpful to reduce temperature that plant coverage rate be raised.

• Electrical & Electronic Materials
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• v.10 no.4
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• pp.327-333
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• 1997

Experiments on mechanical fatigue were conducted using the specimens which were cut from hydrogen cooled generator(rated 22kV and 50OMW) stator windings. We have investigated the aged mechanism of mica/epoxy insulation systems under air or hydrogen by both the tensile and compressive loadings. The fracture of generator stator windings is generally affected by mechanical stress. Thus, the tensile strength test were conducted. In this case, the maximum strength and strain are quite different between sound and aged specimens. It is observed that low bonded interface parts of tapes generally have lower strength than those of normal tapes which causes stress. In order to estimate the effects of cyclic load by the electromagnetic forces while the generator starts/stops, the mechanical fatigue test was also conducted. It is confirmed that the equation of expected life depends on stress amplitude and number of cycles. Though the stress amplitude and number of cycles are very tiny, the tensile fatigue of aged specimens under hydrogen atmosphere is bigger than those under air. In the case of hydrogen atmosphere, the tensile stress gives bigger effect than the compressive one.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.702-707
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• 2008

Improving quality of life and wellbeing of the residential environment and increased interests and importance is growing confidentiality, insulation, high-rise due to a lack of ventilation and indoor air pollution. Several human diseases caused tremendously due to the indoor air which consists of formaldehyde, radon, pollutants such as volatile substances that is called the phenomenon of a new house syndrome. It has become a world-wide issue that the United States, Japan and several other countries of Europe are showing more interests. Furthermore, a lot of damages caused by the syndrome occurs in the new house should be resolved by somehow is urgent. Thus, this study would like to propose the measures based on the whether condition and the way of heating in korea against a new house syndrome via analysis of indoor contaminant Reduction comparison according to vary ventilation and humidity when operating bake-out on a new apartment.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1117-1124
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• 2009

Under frame side sill of rolling stock structure is designed for preventing corrosion in order to meet mechanical requirements. However during long operation time more than 20 years, there are corrosion in the under frame side sill caused by environmental effect, vibration and etc. So, detection and evaluation of the corrosion ill the under frame nondestructive is one of important issues to extend their life time. Most of nondestructive methods are not easy to apply for detecting corrosion in the under frame side sill, since the under frame side sill consist of there layered with different material (stainless steel - stainless steel - mild steel) and each layer is connected by spot weld and plug weld. Fortunately, pulsed eddy current method claimed that it can be measured not only thickness change but also corrosion under their insulation layers. So, in this study, we have investigated performance of pulsed eddy current testing method by measuring thickness variation of fabricate of mock-up specimens. The investigation results obtained from mock-up specimens and the corrosion evaluation results of the aged rolling stocks will be presented.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.42-48
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• 2020

As global warming accelerates, eco-friendly electric cars are being developed to reduce carbon dioxide emissions, and power conversion inverters are used to drive motors. Among inverter components, DC-link capacitor is heated by high current usage, which causes problems such as performance and life-saving of inverter. Although metal cases with good thermal performance have been used to solve this problem, it is difficult to apply them in practice due to insulation problems with other parts. In this paper, the Heat-Generation influence factor of DC-link capacitor is analyzed. Variables on heat-generation are set at 3 levels for film width, inductance, and film thickness. Box-Behnken to 13 tests using the design and minimal deviations, e.g. through the experiment three times by each level. The surface of the film k type by attaching the sensor current is measured temperature. Capacitance was set to a minimum level of 200 ㎌ and had a frequency of 16 kHz with Worst case, ambient temperature of 85℃ and a ripple current of 50 Ams was applied. The temperature at the measurement point was collected in the data logger after sampling at 1 minute intervals for 2 hours after saturation with the ambient temperature. This experiment confirmed that setup factors are correlated with heat-generation.