• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2009년도 춘계 종합학술대회 논문집
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• pp.35-39
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• 2009

단조프레스기의 유압실에서 배관의 연결부위의 손상으로 인한 누유는 인명피해와 기계 파손의 위험성이 있어 이를 조기에 발견하여 예방하는 시스템이 필요하다. 본 논문에서는 원격지에서 회전형 카메라를 이용하여 유압유의 누유여부를 자동 인식하는 시스템을 구현 하였다. 구현한 시스템은 레이블링 과정에서 후보누유영역을 나타내는 최소경계사각형(MBR)을 구하고 MBR의 넓이와 높이 및 MBR의 면적과 후보 누유 영역의 면적비를 이용하여, 올바른 누유영역을 추출하였다. 실험을 통하여 제안한 시스템이 여러 가지 조명 환경에서도 누유영역을 정확하게 찾아내는 것을 확인하였다.

• 한국농공학회지
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• 제36권1호
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• pp.141-152
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• 1994

Our experiment investigated the degree of soil contaimination caused by oil leakage. Each soil sample was taken by boring 5, 8m below the test areas, located 5 to 30m from storage tanks at oil stations. According to the results from a series of laboratory tests(both soxhiet extract test and gas chromatograph test), Traces of a light oil were found in all samples except in Dj8, rocky soil and gasoline and petroleum were not detected. We concluded that soil contamination was caused by the corrosion of storage tanks or alternatively by oil overflow caused during the flooding of underground water seeping into the tank during heavy rain fall or the spillage caused by carelessness during lubrication. Old stations without a concrete box enclosing their metal tanks run a greater risk of oil leakage. To research the effect of oil leakage on plant growth and underground water, We examined the results of research conducted overseas. According to these results, when oil leakage occurs, plant growth is repressed and agricultural crops experience low productivity levels. Also, the contamination of underground water can be serious when oil spreads to the aquifer layer. As a result of these problems, to prevent oil leakage and minimize its contaminating effects at oil stations, it is necessary to improve facilities of storage tanks and have the monitoring system of oil leakage.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.207-210
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• 1998

Surface electrical conduction in insulator is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the widely used materials for outdoor insulator - porcelain, EPDM, Silicone rubber - were discussed by measuring properties of average leakage current and scintillation discharge pulses under artificial contamination conditions. The artificial contaminations used were deionized distilled water fog, 0.5wt% NaCl salt fog of light pollution and 2wt% NaCl salt fog of medium pollution. The average leakage current was appeared linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage was most different to that in case of dry and clean condition. In case of salt fog pollution condition. The leakage current was increased above critical voltage. The scintillation discharges were also activated at the level the leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• Korean Chemical Engineering Research
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• 제54권2호
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• pp.274-277
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• 2016

녹색 발광다이오드의 다양자우물층과 전자막이층 사이에 p형 중간층 삽입이 소자의 특성에 미치는 영향이 소자 시뮬레이션을 통하여 연구되었다. 중간층의 Mg 도핑 깊이에 따른 발광다이오드의 전류-전압, 발광파장, 누설전류, 광효율 특성이 분석되었으며 최적의 발광 특성을 나타내는 소자 구조가 제시되었다. 중간층 전 영역이 p형으로 도핑된 구조와 30 nm까지 도핑된 구조는 누설전류 억제를 통하여 녹색 발광다이오드의 가장 큰 문제점 중에 하나인 효율 드룹 현상을 효과적으로 완화하였다. 특히, 30 nm까지 도핑된 구조는 전류-전압 및 발광 특성에 있어서 가장 향상된 결과를 보였다.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1879-1883
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• 2018

We analyzed the deep-trap states of GaN/InGaN ultraviolet light-emitting diodes (UV LEDs) before and after electrical stress. After electrical stress, the light output power dropped by 5.5%, and the forward leakage current was increased. The optical degradation mechanism could be explained based on the space-charge-limited conduction (SCLC) theory. Specifically, for the reference UV LED (before stress), two sets of deep-level states which were located 0.26 and 0.52 eV below the conduction band edge were present, one with a density of $2.41{\times}10^{16}$ and the other with a density of $3.91{\times}10^{16}cm^{-3}$. However, after maximum electrical stress, three sets of deep-level states, with respective densities of $1.82{\times}10^{16}$, $2.32{\times}10^{16}cm^{-3}$, $5.31{\times}10^{16}cm^{-3}$ were found to locate at 0.21, 0.24, and 0.50 eV below the conduction band. This finding shows that the SCLC theory is useful for understanding the degradation mechanism associated with defect generation in UV LEDs.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.214-234
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• 1995

The purpose of this work was to study the compatibility of several commercially available dentin adhesives with composite resins. In this study, V-shaped cavity preparations were created on both buccal and lingual surfaces of 60 extracted human premolars($3mm{\times}3mm{\times}2mm$ deep). Preparations were located such that the occlusal margins were on the enamel and the gingival margins were on the cementum(1mm below the CEJ). These specimens were randomly divided into three equal groups. Three dentin adhesives(Scotchbond Multi-Purpose, All Bond 2, Prisma Universal Bond 3)were applied to the cavity in accordance with each manufacturer's instructions. The teeth in each group were restored with four composite resins(Silux plus, Z100, Bisfil, Prisma TPH) in three increments, with each increment light-cured for 40 seconds. All specimens were exposed to 500 cycles of thermal stress. Specimens then placed in a silver nitrate solution(50% by weight) and stored in darkness for 24 hours. They were then immersed for 6 hours in photographic developing solution under flourescent light. Specimens were sectioned buccolingually through the center of the restoration and observed under a binocular stereoscope. To compare the marginal leakage, ANOVA and Dunkan's multiple range tests were used in analysis. Selected samples were further studied using scanning electron microscopy(XL20, Philips, The Netherlands). The results were as follows. 1. In all groups, the enamel margin showed significantly less leakage than the cementum margin. 2. No statistically significant differences were found in microleakage when composite resins were used with their proprietary dentin adhesives. 3. In comparison between dentin adhesives, Prisma Universal Bond 3 showed significantly less leakage at the enamel margin and Scotch bond multi-purpose showed significantly less leakage at the cementum margin than the other groups. 4. In comparison between composite resins, Silux Plus showed significantly more leakage than other groups at the enamel margin and no statistically significant differences were found in microleakage at the cementum margin. 5. According to the backscattered scanning electron microscope, microleakage occurred via gaps at the dentin adhesives/dentin interface.

• 구강회복응용과학지
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• 제32권3호
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• pp.184-193
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• 2016

목적: 중합 시간이 bulk fill 유동성 복합레진의 미세누출에 미치는 영향을 마이크로시티를 이용하여 평가하고자 하였다. 연구 재료 및 방법: 30개의 발거된 인간 대구치에 변형된 2급 와동인 vertical slot cavity를 형성하였다. SonicFill과 SureFil SDR flow을 단일 충전하였으며, 다른 중합시간(20, 40, 60초)으로 광중합 하였다. 모든 표본은 5000번의 thermal cycle을 시행하였다. 치아는 silver nitrate 용액에 24시간 동안 침전 후 8시간 동안 현상액에 침전하였다. 마이크로시티를 사용하여 시편을 촬영 후 침투된 silver nitrate solution을 3차원적으로 재건하여 그 부피를 측정하였다. 변연 누출 결과값의 통계 처리는 Mann-Whitney test를 사용하였다. 결과: 광중합 시간의 증가는 두 bulk fill 유동성 복합레진에서 변연 누출을 증가시켰다. 두 복합레진 사이 유의한 차이는 없었다. 결론: 중합 시간은 bulk fill 유동성 복합레진의 변연 누출을 증가시킬 수 있는 요인이었다. 또한 마이크로시티를 통해 레진-치아 계면에서 변연 누출의 양을 비파괴적 방법으로 3차원적으로 재건하여 측정할 수 있었다.

• 치위생과학회지
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• 제11권4호
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• pp.333-337
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• 2011

본 실험에서는 광중합형 임시충전재의 사용기간(1일 후, 3일 후, 7일 후)동안 구강 내의 수분과 온도변화 및 교합력에 의한 미세누출의 가능성을 알아보기 위하여 무게 및 압축강도를 측정하고 열 순환 횟수에 따라 충전재와 와동면 사이의 미세누출을 평가하고자 2종의 광중합형 임시충전재를 사용하여 실험한 결과는 다음과 같다. 1. 광중합형 임시충전재는 사용기간에 따라 측정한 무게는 증가되었다. 제품 간의 비교결과는 Quicks의 무게가 더 높게 나타났다. 2. Spacer의 압축강도는 사용기간에 따라 유의한 차이가 있으나 Quicks의 압축강도에서는 유의한 차이가 나타나지 않았다. 유의한 차이를 보인 Spacer에서는 3일차에서 압축강도가 크게 증가되었다. 3. 열 순환 횟수에 따른 미세누출은 7,000번 실시한 군에서 미세노출이 가장 높게 나타났고, 1,000번 실시한 군과 3,000번 실시한 군은 7,000번 실시한 군보다 통계학적으로 낮은 미세누출을 나타내었다. 4. 사용기간에 따른 무게와 압축강도 및 미세누출사이의 상호연관성이 나타났다. 본 연구에서는 사용기간 경과에 따라 미세누출의 증가를 가져왔으나 수복 후 시간이 경과함에 따라 미세누출이 증가하는 것은 자명한 사실이므로 향후 광중합형 임시충전재의 미세누출을 평가를 위해서는 습식분석을 통하여 화학적 결합을 유도하는 재료의 조성을 분석하는 방법을 부여하는 것이 미세누출 평가에 적절하다고 사료된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.293-296
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• 1998

Surface electrical conduction in insulator is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the widely used materials for outdoor insulator - porcelain, EPDM, Silicone rubber - were discussed by measuring properties of average leakage current and scintillation discharge pulses under artificial contamination conditions. The artificial contaminations used were deionized distilled water fog, 0.5wt% NaCl salt fog of light pollution and 2wt% NaCl salt fog of medium pollution. The average leakage current was appeared linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage was most different to that in case of dry and clean condition. In case of salt fog pollution condition, The leakage current was increased above critical voltage. The scintillation discharges were also activated at the level. the leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• Restorative Dentistry and Endodontics
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• 제7권1호
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• pp.131-138
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• 1981

The purpose of this study was to evaluate the marginal leakage of composite resin. Preparing 144 class V cavities on freshly extracted noncarious teeth, composite resins were prepared and inserted by one dentist according to the manufacturer's instructions. The experiments were performed in two different groups; In group I; Class V cavities with $90^{\circ}$ cavosurface angle, In group II; Class V cavities with $135^{\circ}$ cavosurface angle. And each group was divided 2 subgroups; In control group; composite resin restoraions without acid etch technique. In experimental group; composite resin restorations with acid etch technique. All specimens were immersed in 0.05% crystal violet solution. Before examination, the restored teeth were subjected to thermal stress. The specimens were sectioned occlusogingivally through the center of the restorations with a diamond disk. The sections were examined under a reflected light microscope at 1 day, 7 days and 30 days after immersing the specimens in dye solution. The results were as follows; 1. Control group of group I and group II showed marginal leakage. 2. The degree of marginal leakage in experimental group was greater reduced than control group. 3. In control group, the degree of marginal leakage in group I was greater than group II. 4. In experimental group, there is not statistical differences of the degree of marginal leakage between group I & group II.