• 자원환경지질
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• 제50권6호
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• pp.497-508
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• 2017

이 연구는 장기간 백색 피복물질로 덮여 있던 승가사 석조승가대사좌상의 보존처리 직후 상태를 기록하기 위해 수행하였다. 좌상과 더불어 석조 광배도 함께 검토되었으며, 정밀조사와 비파괴 진단을 통해 자료를 확보하였다. 표면 손상도 평가 결과, 좌상과 광배 모두 물리적 손상은 크지 않은 것으로 나타났으나 변색으로 인한 화학적 손상률은 비교적 높았다. 초음파 측정을 이용한 물성진단 결과, 좌상과 광배의 평균 초음파속도는 3,570 m/s와 3,373 m/s로서 3등급(MW)에 해당하는 양호한 물성을 갖는 것으로 나타났다. 좌상의 표면 피복물질에서는 Ca, Ti, Pb, Fe, Al 및 Si가 검출되었는데, 이는 호분($CaCO_3$) 또는 석회($CaO{\cdot}Ca(OH)_2$)와 규산염광물의 조성이 복합적으로 작용한 것이다. 또한 Ti과 Pb은 백색안료인 타이타늄화이트($TiO_2$)와 연백($2PbCO_2{\cdot}Pb(OH)_2$)의 성분으로 판단된다. 따라서 승가대사좌상은 과거에 호분 또는 석회로 칠해진 이후, 타이타늄화이트와 연백에 의해 덧칠되었던 것으로 해석할 수 있다.

• Current Photovoltaic Research
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• 제5권4호
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• pp.135-139
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• 2017

We fabricated two different transparent conducting oxide thin films of ZnO doped with Ga ($Ga_2O_3$ 0.9 wt%) as well as Al ($Al_2O_3$ 2.1 wt%) (GAZO) and ZnO doped only with Al ($Al_2O_3$ 3 wt%) (AZO). It was investigated how it affects the moisture resistance of the transparent electrode. In addition, $Cu(In,Ga)Se_2$ thin film solar cells with two transparent oxides as front electrodes were fabricated, and the correlation between humidity resistance of transparent electrodes and device performance of solar cells was examined. When both transparent electrodes were exposed to high temperature distilled water, they showed a rapid increase in sheet resistance and a decrease in the fill factor of the solar cell. However, AZO showed a drastic decrease in efficiency at the beginning of exposure, while GAZO showed that the deterioration of efficiency occurred over a long period of time and that the long term moisture resistance of GAZO was better.

• 한국응용과학기술학회지
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• 제25권2호
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• pp.151-159
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• 2008

The flame-retardant coatings were prepared by blending the synthesized triphosphorus modified polyester in the previous paper and hexamethylene diisocyanate-trimer and curing it at room temperature. The characterization of the films of the prepared coatings was performed. It was confirmed that no deterioration of physical properties of PU coatings was observed with the increasing phenylphosphonic acid (PPA) contents. Flame retardancy was tested by a $45^{\circ}$ Meckel burner method and LOI method. With the $45^{\circ}$ Meckel burner method, CATBTP-20C and CATBTP-30C that contain 20 wt% and 30 wt% of PPA, flame retarding component, respectively, showed the first grade flame retardancy with $2.8{\sim}3.9\;cm$ of char length ; and, with LOI method, they exhibited a good flame retardancy as a range of $30{\sim}32%$ of combustion values.

• 보존과학연구
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• 통권25호
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• pp.171-195
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• 2004

This research presents an evaluation of the weathering and deterioration state of the Wanggung-ri five-storied stone pagoda in the Iksan (National Treasure No. 289) and suggests conservational schemes. A deterioration map of the pagoda was drawn from the aspects of petrological, physical, chemical, biological, structural and artificial weathering.The rock properties consisting of the pagoda were medium-grained biotite granite that had leucocratic phenocryst developed in parts. The body of each story suffered severely from the secondary contamination that turned the colors into light grey, pitch dark, yellowish brown, and reddish brown as well as granular decomposition, exfoliation and peel-off. The roof stones were heavy exfoliated or peeled off in most of the cases. In addition to the fine cracks, there were layered cracks on the corners. The roof stones of the3rd and 4th story in the north and west side had some stones fall-off, while those of the 2ndstory in the north side had steel reinforcement filled for a fixing purpose. Those of the 5th story showed big gaps that must have originated from cracks and were easily subject to granular decomposition and rainfall. The inside clay filler was missing in the lower part of the roof stones of the 4th and 5th story and the supporting stones, which were thus covered by light grey or pitch dark sediments. The contact area of the materials was about 70 % in the parts where there was a space due to the filler missing and washigher than 90 % in the lower parts of the pagoda. About 90 % or more of the roof stones surface of each story were covered by aerial plants that formed a thick biological mat. Thus it seemed necessary to come up with the conservational measures to remove the plans living on the surface of the stone materials, with the plans to prevent rain from falling inside, and with the water repellent and hardening treatments to postpone the surface weathering of the rock properties. All those measures and plans must be based on the results of long-term monitoring and thorough detail investigations.

• Tribology and Lubricants
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• 제22권5호
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• pp.260-268
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• 2006

The dielectric constants of used gasoline engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$ Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz,,and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 4% for gasoline engine oil.

• Tribology and Lubricants
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• 제22권5호
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• pp.290-300
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• 2006

The dielectric constants of used diesel engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$. Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz, and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 10% for diesel engine oil.

• 보존과학회지
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• 제25권4호
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• pp.383-398
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• 2009

이 연구에서는 비파괴 기법을 활용하여 관룡사 약사전 벽화에 채색된 안료의 화학적 특성을 규명하고, 손상유형에 따른 정밀진단을 통해 훼손도를 정량적으로 평가하였다. 각 색상에 따른 추정 안료는 기존의 연구와 동일한 것으로 확인 되었으나, 청색계통과 화조화의 바탕으로 채색된 녹색계통의 안료에서 검출된 Co는 지금까지 전통 채색 안료에서 확인 된 바 없는 특이한 결과이다. 훼손도 진단을 위해 초음파 측정, 적외선 열화상 촬영 등을 실시한 결과, 관룡사 약사전벽화에 발생한 균열 및 박리 박락은 수분의 영향으로 판단된다. 따라서 이 벽화의 장기적인 보존을 위해서는 벽화로 유입되는 수분의 침투경로를 정확히 파악하고 효율적인 주변환경 관리를 통해 장기적인 보존대책을 마련해야 할 것이다.

• 한국식품조리과학회지
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• 제19권4호
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• pp.439-446
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• 2003

This study was performed to investigate the change in the chemical components of red pepper powder using different packaging materials and various storage conditions. Red pepper powders with 11 and 15% initial moisture content were packed with five different materials and stored at different temperatures (0, 20, and 30 C) for a one year period. Over the storage period, each combination was periodically sampled, and examined for composition changes. The five packaging materials were: linear low density polyethylene(LLDPE), nylon/LLDPE(Ny/LLDPE), saran coated ethylene vinyl acetate copolymer/linear low density polyethylene(B650), nylon/Tie/nylon/ethylene-vinyl alcohol copolymer/nylon/Tie/LLDPE(RDX-2787) and oriented polypropylene/alumimum/LLDPE(OPP/Al/LLDPE), and the three storage conditions were (28.3${\pm}$1.0)$^{\circ}C$ with (15.5${\pm}$2.8)% relative humidity, (18.6${\pm}$0.5)$^{\circ}C$ with (46.6${\pm}$4.9)% RH, and (0${\pm}$2)$^{\circ}C$ with (80${\pm}$10)% RH, respectively. The moisture contents of all samples changed according to the relative storage humidity, except those of the samples packed with OPP/Al/LLDPE, which remained constant throughout the storage period. The capsaicinoids content of the red pepper powder did not change significantly for 6 months, but gradually decreased after that until about 85% of the original amount remained at the final stage of storage. The ASTA color values of all samples decreased gradually throughout the storage period. The higher the storage temperature, the more severe the deterioration. The color deterioration seemed greatly related to the existence of oxygen, as the deterioration was especially severe in the samples packed with LLDPE and B650, where the oxygen transmission rate were highest among the five packaging materials.

• 사물인터넷융복합논문지
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• 제8권2호
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• pp.7-12
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• 2022

케이블 사고의 주요 원인은 케이블 자체 또는 내·외적으로 전기적, 기계적, 화학적, 열적, 수분침입 등으로 인한 열화의 가속화로 절연성능 감소되고 절연파괴가 발생하여 케이블 사고를 유발하게 된다. 케이블 사고는 과전압, 과전류의 영향으로 절연이 불량한 부분에서 발생할 수 있으므로, 변압기, 차단기의 이상여부, 상간불평형에 의한 지락사고 등을 종합적으로 분석할 필요성이 있다. 케이블의 절연파괴에 의한 지락사고는 케이블 자체의 결함, 케이블 시공불량 뿐만 아니라 운영상의 영향, 전기설비(개폐기, 차단기 등)의 운전 시 아크 등에 의해 발생할 수 있어 사고시점을 전후로 운전 데이터 및 사고 이력에 대한 분석이 필요하다. 이 연구에서는 국내의 한 공장에서 발생한 케이블 사고의 분석을 통하여 케이블 사고의 원인을 고찰하고자 한다.

• 한국구조물진단유지관리공학회 논문집
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• 제26권1호
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• pp.1-9
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• 2022

제설제는 동절기 도로 위의 눈을 녹이기 위하여 사용되고 있으나, 서울과 같은 대도시에서 교통이 밀집한 도로 시설물의 열화를 촉진시키는 주요 요인 중의 하나이다. 도로 시설물의 합리적인 유지관리 전략을 수립하기 위하여 제설제에 노출된 도로 시설물의 환경분석이 필요하다. 본 연구는 서울시의 적설량 및 사용된 제설제량을 토대로 외래 염소농도를 계산하였다. 평균 표면 염소이온량을 구하고자 서울시의 5년간 기후환경 및 제설제 사용량을 이용하였으며, 주간선 및 보조간선율 17.5 ~ 30%, 제설제 노출 유효면적율 50 ~ 80% 수준에서 검토하였는데, 농축 속도는 0.073~ 0.077%/년, 최대 표면 염소이온량은 콘크리트 중량대비 2.2 ~ 2.31% 수준이었다. 본 연구결과는 염소이온 프로파일의 예측 또는 콘크리트 구체의 화학적 부식정도 등으로 종합적인 유지관리 대책을 수립하는데 활용될 수 있을 것으로 기대된다.