• 한국대기환경학회지
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• 제9권3호
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• pp.191-199
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• 1993

This paper describes the results of a systematic study to determine the characteristics of particle generated from various types of asbestos containing material(ACM) and manmade fiber material(MMFM) during operations of cutting and grinding in laboratory and workplace. Tests were conducted with a specially designed glove box which allowed complete sampling of the generated asbestos fibers. Specificially, air measurements were made during ACM and MMFM installation in building. All personal air samples collected were identified by polarized light microscopy(PLM), X-ray diffraction(XRD) and scanning electron microscope with energy dispersive X-ray analysis(SEM/EDXA). Also, the samples were counted by phase contrast microscope(PCM) in order to compare the results with the permissible exposure standard for workplace. Results indicate that the characterisitcs of fibers found in the roofing sheet, the ceiling and the wall insulation boards were identical to those of asbestos, while the characteristics of fibers found in the ceiling insulation board, the floor tile and the sprayed on insulation products in parking area were identical to those of asbestos, while the characteristics of fibers found in the ceiling insulation board, the floor tile and the sprayed on insulation products in parking area were identical to those of rock wool. The concentrations of airborne fibers from various building materials cut by a grinder for 5 minutes were in the ranges of 0.09 $\sim$ 1.71 fibers/cc(f/cc). The highest concentration(1.71f/cc) was found during grinding the wall insulation board which also contains rock wool. The airborne fiber concentrations generated by installing at workplace were ranged from 0.0009 to 0.029 f/cc. All asbestos fibers from the ceiling insulation board at workplace were less than 20$\mu$m in length and more than 20% of them had the average aspect ratio greater than 20. Therefore, for the purpose of decreasing asbestos and man-made fiber concentrations at the workplace, the ceiling and wall board should use strong binding material to increase the binding force with fiber. Also, the permissible exposure standard for workplace(2.0f/cc) in Korea should be constituted below the maximum avaiable concentration measured at glove box.

• 설비공학논문집
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• 제29권5호
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• pp.269-277
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• 2017

This study consists of an analysis of pre-existing ceiling construction systems as well as the development of a replacement unitary, lightweight steel ceiling system and related legal standards. Based on the material conditions and progression of the study, appropriate components were chosen and details were modified by mock-up test. A final study model was evaluated for performance and adaptability based on four parameters (indoor environment, constructability, budget economy, and aesthetics) and compared to the pre-existing ceiling system. As a result of the initial study, a lightweight steel design was created consisting of a reinforced structure with modular bars and entry holes for components. This system was hung directly on the suspension structure. The new design increased lighting and acoustic performance adapted to an indoor environment. Moreover, the speed of construction was increased by approximately 30%, the cost was decreased by approximately 20%, and ceiling aesthetics were improved.

• 한국음향학회지
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• 제37권5호
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• pp.363-368
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• 2018

최근 슬랫형 천장은 음악전용공연장인 음악당에서부터 공항대합실을 포함한 다양한 규모와 용도의 건물에서 그 적용범위가 확대되고 있다. 그러나 이와 같은 구조의 활용에 따른 공간의 실내음향에 미치는 영향에 관한 연구가 거의 없어 공간의 계획 시 활용 가능한 자료가 거의 없다. 본 연구에서는 1/20 축소모형실험을 통하여 shoe-box 형태의 소규모 공연장에서 슬랫형 천장의 적용이 객석의 음향에 미치는 영향을 측정 분석하였다. 실험은 슬랫의 간격 및 설치높이 변화의 조합에 따른 6가지 설치조건들을 대상으로 하였으며, 잔향시간 ($T_{30}$), 명료도 ($D_{50}$ 및 $C_{80}$), 그리고 음의 세기 (G 및 $G_{80}$) 측면에서 그 영향을 분석하였다.

• Architectural research
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• 제14권3호
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• pp.93-98
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• 2012

The objective of the study is to analyze the relative performance of factors affecting indoor air quality in multi-residential buildings in Korea. A study of the factors affecting indoor air quality is essential for establishing indoor air quality management strategies effectively. To observe the indoor air quality response following a modification of a given parameter, a sensitivity analysis was performed. The factors examined for the analysis include; wall/ceiling paper, adhesive for wall/ceiling paper, floor material, adhesive for floor material, and ventilation rate. The Experimental Design which identifies main effects among the design parameters with a few experiments was used to decrease the number of experiments. The simulation for indoor air quality was undertaken using a validated equation. Then, ANOVA(Analysis of Variance) was performed to evaluate the relative importance of each parameter affecting the indoor air quality. The result of the study indicates that the indoor air quality may be influenced most by adhesive for wall/ceiling paper, followed by ventilation rate and adhesive for floor material.

• 한국산업보건학회지
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• 제5권2호
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• pp.137-146
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• 1995

Twenty(20) large commercial buildings located in Seoul with friable sprayed-on surface insulation material on ceilings were investigated for asbestos content in bulk material by polarized light microscopy and for airborne fiber concentrations in buildings by phase contrast microscopy. In addition, such building-related variables as building age, numbers of traffic, airflow, surface conditions of the ceiling, temperature, and humidity were studied for any correlation with airborne fiber concentrations. The results were as follows: 1. Chrysotile asbestos was found in two bulk samples with 3-5% content and with <1%in one sample out of total 20 bulk samples collected. Glass fiber and mineral wool were the two major constituents of the bulk samples. 2. The ceiling surfaces were very friable in 16 buildings and were relatively hard in 4 buildings. The friability of the surface material was dependent upon the type and the amount of binder that had been mixed with the sprayed-on surface material. 3. Airborne fiber concentrations were log-normally distributed and the geometric mean(geometric standard deviation) fiber concentrations in the underground parking lots, inside buildings, and outdoor ambient air were 0.0063(1.97)f/cc, 0.0068(2.29)f/cc, and 0.0033(2.36)f/cc, respectively. 4. No significant relationship of airborne fiber concentrations and all building-related variables studied except humidity was found. The results of this study suggest that the sprayed-on surface insulation material found in some commercial buildings may possibly be contaminated with asbestos. Since most of the ceiling surfaces surveyed were very friable and poorly maintained and the airborne fiber concentrations were relatively high, there is a possibility of asbestos fiber contamination in these buildings, particularly at those buildings with asbestos-contaminated surface material. Since poorly maintained surface conditions were thought to be a source of high airborne fiber concentrations, there is a urgent need of a systematic operation and maintenance program. Further study of non-occupational asbestos exposure in general population utilizing advanced analytical technique such as transmission electron microscopy is highly recommended.

• 한국산학기술학회논문지
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• 제11권9호
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• pp.3141-3147
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• 2010

LED 조명등의 효율 및 수명을 단축시키는 가장 중요한 원인은 정션온도 상승이며, 이를 해결하기 위해 고효율 방열 패키징, 고전도율 소재 개발, 접촉저항 개선 및 히트싱크 최적화 등과 같이 다양한 방열성능 향상 연구가 이루어지고 있다. 하지만 지금까지의 대부분의 연구는 LED 조명등이 단지 대기 중에 노출되었다고 가정하였기 때문에 실제 실링 유닛과 함께 천장에 장착되었을 때의 방열성능은 아직 보고되지 않고 있다. 따라서, 본 연구에서는 MR16 LED 조명등을 이용하여 실제 설치조건에 따른 정션온도 변화를 규명하고 이를 통한 더욱 정확한 LED 조명등 수명 및 효율 예측을 이루고자 하였다.

• 한국실내디자인학회논문집
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• 제23호
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• pp.19-25
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• 2000

This study aims by analysing the interior design elements trends of current medium size office buildings in Seoul. The analysing objects are ceiling, floor, wall, and illumination plan of current office buildings. Analysing tools are finishing material and color of each part. Analysing areas are lobby area, deskwork area, conference area, welfare area, public area(rest room, corridor, stair). The interior design elements of lobby shows a lots of different features then the other areas in ceiling, floor, and wall design. Such difference appears at finishing material especially, and the coloring is more splendorous then the other areas. Desk work area and conference area have similar characteristics in finishing materiors and colors, and they usually follow the needs of function. Walfare area shows more splendorous feature then deskwork and conference area, and designed by various materials and colors. Public area also shows very active design concept then past times.

• 한국소음진동공학회논문집
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• 제17권4호
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• pp.342-349
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• 2007

Following the 2002 World-Cup held in Korea, studies have been actively conducted on plans to utilize all-weather stadiums of fine figures, where large-scale spaces are available for various utilizations. In Japan, dome-type stadiums have been built and are utilizing across the whole nation not only for sports events but also variety of other large-scale events. PTFE(poly tetra fluoro ethylene) is one of the membrane material mainly used for the outer ceiling surface of membrane structures. However, there has not been enough research on the acoustical properties of PTFE membrane material which has been widely used in the multi-purpose stadiums. In this study, air permeability values and sound absorption coefficient of PTFE membrane materials were measured and evaluated in the gymnasium. From the results of measurements of sound absorption coefficient and air permeability of inner membrane materials, it was found that the sound absorption coefficient was good in the air permeability range of $5{\sim}15\;cc/cm^2/s$. Also the relation ship between air permeability and sound absorption coefficient was very high and the sound absorption coefficient was the highest in the range of $6{\sim}9\;cc/cm^2/s$. Secondly, an analysis on the measurements sound absorption characteristics of inner membrane material reveals that the overall sound absorption coefficient was stabilized(higher than 0.5 throughout the whole frequency bands) when the air space behind the membrane material was deeper than 600 mm. When PTFE sound absorptive membrane material was installed in the ceiling of gymnasium, it was confirmed that sound absorptive membrane material can reduce reverberation and increase speech intelligibility in the gymnasium.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.898-904
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• 2016

In this study, we have dealt with a design characteristic of outer-rotor type permanent magnet (PM) motor applied for Engine Cooling Fan (ECF). When we design a motor with structure like this type, it is required as a requisite to consider 3-Dimensional (3-D) effect by implementing a non-linear Finite Element Analysis (FEA) due to a yoke-ceiling, which is perpendicular to the axis of rotation. We have analyzed identical models under three different conditions. The analysis has been performed through a non-linear 2-Dimensional (2-D) and 3-D FEA. Finally, the results have been compared with Back Electro-Motive Force (BEMF) value of actual motor model. As a result, a yoke-ceiling function as an additional flux path and the operating point on B-H curve of rotor material is shifted to non-saturation region relatively. Accordingly, magnetic flux linkage can be increased and motor size can be decreased under same input condition to satisfy ECF specification, such as torque.

• 한국실내디자인학회논문집
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• 제23권2호
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• pp.147-155
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• 2014

The purpose of this study was to investigate expression characteristics of korean traditionality in restaurants & Ccfes which adapted thatched roof & shingle-roofed house. As a method of this study, a case study was made to investigate for exterior and interior elements(roof type, facade, floor, wall, ceiling, door & window) of 12 restaurants & cafes in Seoul and Kyunggi Province from June 10, 2013 to December 1, 2013. The results of this study were as follows: First, traditional transformation was mostly used among the traditional expression methods. But, there was not many traditional reinterpretation method. Second, looking at each component, traditional reproduction method mostly used for roof, column and ceiling to emphasize facade. Traditional transformation method can be divided into 3 ways in detail. The first method is mixing materials of modern and traditional, and the second one is transforming traditional material and combining this with modern one. The third is removing traditional material completely and transforming totally into modern materials. Third, traditional high quality noble houses are found in luxurious Korean restaurants and luxurious cafes while common houses are found in local food restaurant and cafes. It is because traditional common houses are still considered as low quality of design and it may prevent common houses from becoming high quality of design.