• 한국표면공학회지
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• 제48권2호
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• pp.33-37
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• 2015

High efficiency LED device is being concerned due to its high heat loss, and such heat loss will cause a shorter lifespan and lower efficiency. Since there is a demand for the materials that can release heat quickly into the external air, the organic insulating layer was required to be replaced with high thermal conductive materials such as metal or ceramics. Through anodizing the upper layer of Al, the Breakdown Voltage of 3kV was obtained by using an uniform thickness of $60{\mu}M$ aluminum oxide($Al_2O_3$) and was carried out to determine the optimum process conditions when thermal cracking does not occur. Two Ni layers were formed above the layer of $Al_2O_3$ by sputtering deposition and electroplating process, and saccharin was added for the purpose of minimizing the remain stress in electroplating process. The results presented that the 3-layer film including the Ni layer has an adhesive force of 10N and the thermal conductivity for heat dissipation is achieved by 150W/mK level, and leads to improvement about 7 times or above in thermal conductivity, as opposed to the organic insulation layer.

• 한국세라믹학회지
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• 제28권1호
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• pp.11-18
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• 1991

A precipitation method, one of the most effective liquid phase reaction methods, was adopted in order to prepare high-tech Al2O3/ZrO2 composite ceramics, and the effects of stress-induced phase transformation of ZrO2 on thermal shock behavior of Al2O3-ZrO2 ceramics were investigated. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent. Metal hydroxides were obtained by single precipitation(process A) and co-precipitation(process B) method at the condition of pH=7, and the composition of Al2O3-ZrO2 composites was fixed as Al2O3-15v/o ZrO2(+3m/o Y2O3). Critical temperature difference showing rapid strength degradation by thermal shock showed higher value in Al2O3/ZrO2 composites(process A : 20$0^{\circ}C$, process B : 215$^{\circ}C$) than in Al2O3(175$^{\circ}C$). The improvement of thermal shock property for Al2O3/ZrO2 composites was mainly due to the increase of strength at room temperature by adding ZrO2. The strength degradation was more severe for the sample with higher strength at room temperature. Crack initiation energies by thermal shock showed higher values in Al2O3/ZrO2 composites than in Al2O3 ceramics due to increase of fracture toughness by ZrO2.

• Korean Chemical Engineering Research
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• 제43권5호
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• pp.632-636
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• 2005

본 실험은 화학적 표면처리된 탄화규소(SiC)가 PMMA 나노복합재료의 열안정성 및 기계적 계면특성에 미치는 영향에 대하여 고찰하였다. 표면처리된 SiC의 표면특성은 산 염기도, 접촉각 측정 그리고 FT-IR을 사용하여 알아보았으며, SiC/PMMA 나노복합재료의 열안정성은 열중량 분석을 통하여 알아보았다. 또한, 기계적 계면물성은 임계응력 세기인자(critical stress intensity factor, $K_{IC}$)와 임계 변형에너지 방출속도(critical strain energy release rate, $G_{IC}$) 측정을 통해 고찰하였다. 실험결과, 산성 용액으로 표면처리한 SiC(A-SiC)의 표면 산도가 염기성(B-SiC) 또는 표면처리 하지 않은 SiC(V-SiC)보다 높았으며, 접촉각 측정 결과, 산성 용액으로 표면처리는 극성요소의 증가에 기인하는 A-SiC의 표면자유에너지를 증가시켰다. $K_{IC}$와 $G_{IC}$같은 기계적 계면성질은 A-SiC가 향상되었는데, 이러한 결과는 충전재와 고분자 사슬간의 산 염기 상호작용에 의한 계면결합력의 향상에 의한 것으로 판단된다.

• 한국조경학회지
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• 제42권6호
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• pp.21-30
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• 2014

본 연구는 쾌적한 온열환경을 제공하는 공원을 계획하기 위한 방안을 모색하고자, 전형적인 녹지유형인 수림지와 잔디밭의 여름철 열환경을 측정 및 평가하였다. 이를 위해 함양 상림공원을 연구대상지로 하였으며, 대상지 내 녹지유형을 대표하는 수림지와 잔디밭 그리고 대조구로서 포장지에서 열환경을 조사하였다. 기상장비를 활용한 3일 동안(2014년 8월 21~23일, 29~30일)의 정점관측을 통해 열환경 변수인 기온, 상대습도, 풍속 그리고 6방향(동, 서, 남, 북, 하향, 상향) 장파 및 단파 복사를 측정하였다. 측정한 복사량을 근거로 6방향의 향별 가중치를 적용하여 인체가 흡수한 복사량을 구한 후 이를 평균복사온도로 환산하였다. 산정된 평균복사온도와 측정된 기온, 상대습도, 풍속을 바탕으로 PET는 Rayman 1.2, UTCI, OUT_SET$^*$는 UTCI Calculator와 Thermal Comfort Calculator of Richard DeDear로 산정한 후 수림지, 잔디밭 그리고 대조구의 온열쾌적성을 평가하였다. 열환경 및 온열쾌적지수의 평가 결과, 수림지는 포장지에 비해 주간(10:00~16:00)의 기온과 평균복사온도를 $5.9^{\circ}C/35^{\circ}C$ 낮추는 냉각효과를 나타냈으며, 상대적으로 낮은 풍속과 높은 상대습도를 나타냈음에도 불구하고, 온열쾌적지수 개선효과는 매우 크게 나타났다. 반면에 잔디밭은 포장지에 비해 주간(10:00~16:00)의 기온과 평균복사온도를 $0.9^{\circ}C/3^{\circ}C$ 낮추는 미미한 냉각효과를 나타냈으며, 잔디밭의 온열쾌적지수 개선효과는 크지 않은 것으로 나타났다. 한편, 야간(21:00~04:00)의 미기상 및 복사 환경은 일사 부재, 풍속 감속, 상대습도 증가로 인해 수림지, 잔디밭 및 포장지가 비슷하게 나타났다. 이러한 결과는 수림지의 차양 및 증발산 효과는 잔디밭의 증발산 효과에 비해 매우 크기 때문이라 판단되며, 공원의 온열쾌적성을 확보하기 위해서는 녹지의 면적보다 녹지의 용적에 주력해야 한다는 것을 시사하는 것이다. 본 연구는 수림지와 잔디밭에서 공원의 이용자가 체감하는 온열쾌적성을 정량적으로 평가하고, 수림지 및 잔디밭이 가진 온열쾌적지수 개선효과를 규명함으로써 향후 공원계획시 이용자를 고려한 쾌적한 온열환경을 조성하는데 기여할 수 있을 것이다.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.332-337
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• 2018

항공기용 탐조등은 야간 임무 수행 시 탐색 또는 구조 임무에 사용되며, 은폐 상태를 유지하며 작전을 수행할 수 있도록 적외선 광을 제공한다. A기종 회전익 항공기 운용 중에, 적외선 생성을 위한 적외선 투과 필터 유리가 파손되는 현상이 다수 발생하였으며, 이로 인해 은폐능력이 상실되고 정비 소요가 발생하는 등의 문제점이 제기되었다. 본 논문에서는 해당 결함이 발생하는 탐조등의 운용 조건을 시험하고, 그에 따른 결함 원인을 도출한 과정을 기술하였다. 그리고 도출된 원인을 개선하기 위한 여러 가지 방안과 개선 필터 시제품 제작 과정을 정리하였다. 또한 개선된 필터가 장착된 탐조등에 대해 성능시험, 내구성 시험, 항공기 장착시험을 통해 탐조등의 규격에서 제시하는 성능 요구를 만족하는지 검증한 결과를 기술하였다. 시험 및 검증 결과 필터의 파손 현상이 개선되었으며, A 기종 항공기에 개선 필터를 적용한 결과 파손 현상이 더 이상 발생하지 않는 것을 확인하였다.

• Transactions on Electrical and Electronic Materials
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• 제3권2호
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• pp.32-37
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• 2002

This paper gives the basic mechanical properties of indium-tin-oxide (ITO) films on polymer substrates which are exposed to externally and thermally induced bending force. By using modified Storney formula including triple layer structure and bulge test measuring the conductive changes of patterned ITO islands as a function of bending curvature, the mechanical stability of ITO films on polymer substrates was intensively investigated. The numerical analyses and experimental results show thermally and externally induced mechanical stresses in the films are responsible for the difference of thermal expansion between the ITO film and the substrate, and leer substrate material and its thickness, respectively. Therefore, a gradually ramped heating process and an organic buffer layer were employed to improve the mechanical stability, and then, the effects of the buffer layer were also quantified in terms of conductivity-strain variations. As a result, it is uncovered that a buffer layer is also a critical factor determining the magnitude of mechanical stress and the layer with the Young's modulus lower than a specific value can contribute to relieving the mechanical stress of the films.

• 한국전기전자재료학회논문지
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• 제21권3호
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• pp.265-271
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• 2008

TCP(Tape Carrier Package), COG (Chip On Glass), COF(Chip On Film) are three methods for connecting LDI(LCD Driver IC) with LCD panels. Especially COF is growing its portion of market place because of low cost and fine pitch correspondence. But COF has a problem of the lead broken failure in LCD module process and the usage of customer. During PCB (Printed Circuit Board) bonding process, the mismatch of the coefficient of thermal expansion between PCB and D-IC makes stress-concentration in COF lead, and also D-IC bending process during module assembly process makes the level of stress in COF lead higher. As an affecting factors of lead-broken failure, the effects of SR(Solder Resister) coating on the COF lead, surface roughness and grain size of COF lead, PI(Polyimide) film thickness, lead width and the ACF(Anisotropic Conductive Film) overlap were studied, The optimization of these affecting manufacturing processes and materials were suggested and verified to prevent the lead-broken failure.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.145-146
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• 2019

In contemporary residential culture, apartment houses can form individual independent residential areas within narrow territory. By using various building materials compared to the past, apartment house is recognized as an aesthetic space by modern people. However, as the number of cases of tile defects in apartment complexes has surged recently, aesthetic factors and quality of life have been reduced, and hundreds of millions of defects have been charged to builders every year. The tile defects in the apartment complexes of 90 domestic complexes are cracked, lifted, damaged, and dropped off. Most of the tile defects are caused by poor construction, but the defect occurrence rate due to thermal stress mechanism is high. Therefore, this paper investigates the case of tile defects in apartment house and identifies the defects and examines the problems that should be improved to reduce the defects of tiles in the building interior.

• 한국전기전자재료학회논문지
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• 제24권8호
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• pp.609-615
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• 2011

This paper is studied for the improvement of the characteristics of gate oxide with 3-nm-thick gate oxide by deuterium ion implantation methode. Deuterium ions were implanted to account for the topography of the overlaying layers and placing the D peak at the top of gate oxide. A short anneal at forming gas to nitrogen was performed to remove the damage of D-implantation. We simulated the deuterium ion implantation to find the optimum condition by SRIM (stopping and range of ions in matter) tool. We got the optimum condition by the results of simulation. We compare the electrical characteristics of the optimum condition with others terms. We also analyzed the electrical characteristics to change the annealing conditions after deuterium ion implantation. The results of the analysis, the breakdown time of the gate oxide was prolonged in the optimum condition. And a variety of annealing, we realized the dielectric property that annealing is good at longer time. However, the high temperature is bad because of thermal stress.

• ETRI Journal
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• 제26권6호
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• pp.647-652
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• 2004

A new ionic liquid, 1-vinyl-3-heptylimidazolium iodide (VHpII), was synthesized and applied as a redox electrolyte for dye-sensitized solar cells. The chemical structure of the synthesized VHpII was confirmed using $^1H$ NMR. Thermogravimetric analysis showed that the VHpII was stable for thermal stress of up to $250^{\circ}C$. The energy conversion efficiencies of the VHpII-based dye-sensitized solar cells were investigated in terms of the effect of a lithium iodide addition. A solar cell containing the redox couple of VHpII and iodine showed a conversion efficiency of 2.63% under 1 sun light intensity at AM 1.5. Adding 0.4 M LiI results in a conversion efficiency of 3.63%, which was an improvement of about 40%. The increased conversion efficiency was ascribed to an increase in external quantum efficiency.