• 대한전기학회논문지
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• 제35권1호
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• pp.1-7
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• 1986

The GaAs bulk single crystals are grown by the Horizontal Bridgman method. During the growth, one of the problems in Bridgman method is the boat wetting between GaAs molten and silica boat. This boat wetting may result in another nucleation to form twin crystals. In this study, We find that the optimal size for sand blasting is 320 mesh. Backfilling the ampoule with argon gas during the vaccum bake-out decreaes the boat wetting. The reaction mechanism of Ga with quartz to produce suboxide, Ga2O, and sillion is discussed.

• 한국진공학회지
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• 제21권6호
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• pp.287-294
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• 2012

위성체가 작동하는 우주환경인 초고진공상태에서는 각 부품에서 발생 할 수 있는 기체방출로 인해 위성체가 오염되어 위성체의 성능이 저하될 수 있으며, 특히 광학렌즈를 오염시킴으로써 위성체 본연의 임무수행 실패라는 결과를 초래할 수도 있다. 최근 항공우주분야에서 활용 범위가 넓어지고 있는 PZT-5 계열 압전진동자의 위성부품 활용성 연구를 위하여 먼저 Collected Volatile Condensable Material 및 Total Mass Loss을 측정하여 규정된 0.1% 및 1.0% 이하의 값을 얻었고, 한국항공우주연구원에 설치된 베이크아웃(bake-out) 챔버를 이용하여 고온 및 고진공상태에서 500 $ng/cm^2/hr$ 이하의 낮은 Thermoelectric Quartz Crystal Microbalance 값을 얻어 위성체 부품으로의 적합성을 재확인하였다. 압전진동자에 대한 고진공 환경 전후의 압전 특성을 비교 분석한 결과 진공환경에 의한 전기-기계적 특성은 1% 미만으로 큰 변화가 없음을 확인하였다.

• 설비공학논문집
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• 제30권3호
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• pp.116-122
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• 2018

The purpose of this study was to confirm the effects of flush-out in the reduction of formaldehyde concentration in newly built residential buildings. The field measurements were conducted on two complexes of multi-residential buildings which are located in the suburban area of Seoul. About eight samples of residential buildings were selected to measure the changes in formaldehyde concentrations after flush-out from the two apartment complexes. The concentration of formaldehyde was measured using DNPH cartridge and HPLC. From the results of the field measurements, it was established that indoor formaldehyde concentration decreases 27.6~54.2% in the samples after flush-out. The number of days that the flush-out were conducted was noted to have no significant influence on the reduction rate of formaldehyde concentration when the flush-out continued more than 7 days. The comparison with Bake-out showed that flush-out also can reduce formaldehyde in newly built buildings as same levels of it.

• 한국세라믹학회지
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• 제46권2호
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• pp.211-218
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• 2009

For the Y5V characteristic MLCC which is very prone to crack, it is important to to find out the basic cause of the crack. After finding out the crack origin, the materials and processes should be developed to remove the crack. The microstructures of the cracks were investigated using the fractographic method for the various types of cracks such as an exterior crack, a cyclic thermal shock crack, and an piezo-electric crack. It was found out that the crack origin was the pore at the end of the Ni inner electrode after bake-out. Even though the three dimensional crack shapes were different, the crack origins were seemed to be similar. The exterior crack could grow from the origin with the aids of residual and applied stress. FEM (finite element method) analysis was used to calculate the stress distribution of residual and applied stress. And the concept of fracture mechanics was applied for the explanation of the crack initiation and propagation from the stresses concentration.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 동계학술발표대회 논문집
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• pp.29-29
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• 2006

• 한국세라믹학회지
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• 제43권4호
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• pp.253-258
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• 2006

In the lamination process of multi-layer ceramic modules, the occurrence of delamination comes into repeatedly. To completely improve the lamination process of LTCC sheets, a binder film was introduced between the layers. The binder film did not originate the delamination until the thickness under $40{\mu}m$. After lamination, the thickness of the binder film was determined by the infilteraion of binder by the pressure, and after the bake-out, was dependent on the decomposition of binder resin. Any detectable defect was not observed in the multilayer structure with Ag inner electrodes.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1220-1224
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• 2008

Because of the high airtightness and insulation of the building, indoor environment has been largely polluted resulted from insufficient ventilation and occurrence of new air pollutant. These factors have made worse indoor air quality and caused symptoms of the SHS(Sick House Syndrome), MCS(Multi Chemical Sensitivity). The purpose of this study is to present the fundamental strategies for improving the Indoor Air Quality(IAQ) in newly-constructed apartment buildings. To investigate the concentration of indoor air pollutants such as Formaldehyde and VOCs, the field measurement were conducted.

• 대한가정학회지
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• 제44권3호
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• pp.103-113
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• 2006

The purpose of this study was to determine the present condition of sick house syndrome of newly built apartments a mid-sized city. The questionnaire survey was carried out from $19^{th}\;to\;22^{nd}$ of May 2004, with respondents consisting of 160 households living in two apartment complexes of Cheongju. Their residency periods after moving in were within $six{\sim}ten$ months. From the survey results of the respondents, sick house syndrome items revealed high percentages with the highest value of 49.3%. The respondents answered that they knew relatively well about sick house syndrome but they had no knowledge about 'bake-out'. The response percentages of sick house syndrome items in E complex, consisting of $106m^2$ (32 pyeong) size units, were significantly higher than those in A complex, consisting of $76m^2$ (23 pyeong) size units. This result suggests that the pollution levels emitted from interior materials in larger sized apartment units are higher than those in small sized units. The response percentages of sick house syndrome items in houses with fulfilled ventilation which had been ventilated before or after moving in were lower than in houses not ventilated.

• 한국건축시공학회지
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• 제8권5호
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• pp.93-99
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• 2008

The environment draws attention in the global community and a growing number of Koreans have interest in improving the quality of life, the importance of house environment has attracted the attention of the public. Against this backdrop, constructors have unveiled environmentally -friendly projects. However, they failed to establish people-oriented environment by being occupied with maximizing profitability through the improvement of brand image and caused sick house syndrome that has recently made controversy. In this regard, the study analyzed the mechanism of discharge of TVOC, one of the sick house syndrome-causing materials, that affects IAQ and its characteristics and examined the effect that granodiorite has on reduction of the discharge of TVOC in order to minimize damage. Experimental sample consisted of interior finishing materials frequently used in ceiling, wall and floor and adhesives used at a time of construction, and the TVOC of building materials was measured through the use of septum bottle unlike In the existing chamber method. Measures to counter the sick house syndrome were suggested by reducing the possible damage from the stage of selection of building material and by figuring out the effect that the granodiorite has on reduction of the discharge of TVOC.

• 대한환경공학회지
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• 제32권10호
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• pp.973-978
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• 2010

에너지절감에 대한 인식이 높아짐에 따라 점차 건물이 밀폐화되고 있으며, 이로 인하여 실내공기질에 영향을 미치는 건축자재로부터의 휘발성유기화합물 방출에 대한 관심이 높아지고 있다. 그러므로 실내공기질을 개선하는데 있어 건축자재로부터의 VOCs 방출특성을 파악하는 것이 무엇보다 중요하다. 본 연구에서는 우리나라가 온돌문화인 점을 고려하여 대표적인 건축자재인 온돌마루와 접착제를 대상으로, 방출챔버시험을 통하여 온도 및 시간경과에 따른 헥산, 톨루엔 및 TVOCs 방출특성을 살펴보았다. VOCs의 방출속도는 온도와 비례관계를 나타내었으며, 바닥재에 존재하는 VOCs 발생원이 어느 위치에, 어떠한 형태로 존재하느냐가 시간의 경과에 따른 방출특성에 크게 영향을 미친다는 것을 알 수 있었다. 즉, 건축자재로부터의 헥산, 톨루엔의 방출은 전반적으로 초기에 방출속도가 높고 시간이 지남에 따라 점차 줄어드는 경향을 보이고 있으나, 온돌마루로부터의 톨루엔 방출은 다른 양상을 보이는데 시간이 지남에 따라 방출속도가 오히려 증가하여 6시간 경과 후 최대값을 보인 뒤 점차 감소하는 경향을 나타내었다. 이는 온돌마루에 함유되어 있는 톨루엔 발생원이 자재의 내부에 많이 존재하고 있기 때문에 시간이 경과함에 따라 방출속도가 증가했다가 다시 감소하는 경향을 보인 것으로 추정된다. 바닥재로부터의 VOCs 방출특성 실험결과를 종합하여 살펴보면, 온돌시스템에서 방출되는 고농도의 VOCs에 인체노출을 줄이기 위해서는 이사하기 전에 적어도 72시간 이상의 Bake-out 시간이 필요할 것이라 사료된다.