• 대한전자공학회논문지
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• 제27권1호
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• pp.46-50
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• 1990

Heteroface AlGaAs/GaAs drift solar cells with an active area conversion efficiency of 15.9% under one sun and AM 1.5 condition have been grown by molecular beam epitaxy(MBE). These drift solar cells have graded doping profiles in the base and emitter regions. The cells have a short circuit current density (Jsc) of 19.00 mA/cm\ulcorner an open circuit voltage(Voc) of 0.93 V, and f fill factor(FF) of 0.78, respectively. Conventional solar cells with fixed doping profiles were also grown by MBE for comparison with the drift solar cells. Even though the fabrication cost of MBE grown solar cell is higher, the expected highest conversion efficiency of the single or multiple cells could compensate for the increased cost, particularly in case of space applications.

• 태양에너지
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• 제8권2호
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• pp.19-25
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• 1988

[ $SnO_2$ ] thin films have been deposited on the pyrex glasses and silicon wafers by CVD method. Tin oxide films had a good transmittance above 80% in the visible region and the lowest sheet resistance at $520^{\circ}C$. When the ratio of $SbCl_3$ was 2wt%. The optimum conditions were obtained at the oxidation time of 3 minutes in the case that Voc and Jsc were 0.40V and $33.5mA/cm^2$ respectively and the corresponding conversion efficiency was 6.07%.

• Environmental Engineering Research
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• 제22권2호
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• pp.169-174
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• 2017

Vacuum swing adsorption (VSA) is a promising treatment method for volatile organic compounds (VOCs). This study focuses on a VSA process for regenerating activated carbon spent with VOCs, and then investigates its adsorption capacities. Toluene was selected as the test VOC molecule, and the VSA regeneration experiments results were compared to the thermal swing adsorption process. Cyclic adsorption-desorption experiments were performed using a lab-scale apparatus with commercial activated carbon (Samchully Co.). The VSA regeneration was performed in air (0.5 L/min) at 363.15 K and 13,332 Pa. The comparative results depicted that in terms of VSA regeneration, it was found that after the fifth regeneration, about a 90% regeneration ratio was maintained. These experiments thus confirm that the VSA regeneration process has good recovery while operating at low temperatures (363.15 K) and 13,332 Pa.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2002년도 추계학술발표회 논문집
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• pp.189-194
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• 2002

• Corrosion Science and Technology
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• 제6권5호
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• pp.239-244
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• 2007

Corrosion protection of automotive steels has traditionally been assured by using a zinc phosphate metal pretreatment followed by the deposition of a cathodic electrocoat system. This system has been developed and optimized over the years into a highly robust and dependable system with a high performance. However, in terms of efficiency and use of resources and energy, the need is now felt to develop a simpler system with fewer steps, shorter lines, less energy requirements (curing and e-coat deposition) and less stringent waste disposal requirement (phosphate sludge). We report here on the development of a one-step system that can possibly replace both the zinc phosphate and the e-coating processes. Such a system is based on the so-called superprimer concept that we have recently developed for the replacement of chromate pretreatment and chromate-containing primers in the aerospace industry. With some modifications, such systems can also be adapted for use in the automotive industry.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2021년도 추계학술발표대회
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• pp.148-151
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• 2021

본 논문은 oneM2M을 활용하여 스마트시티의 일환으로 사회적 이슈가 되고 있는 미세먼지(PM10, PM2.5) 측정 플랫폼을 설계하였다. 미세먼지 측정 디바이스를 이동식 차량에 부착하여 미세먼지가 측정이 되고 있지 않은 사각지대까지 범위를 넓혀 측정하였다. 또한 미세먼지뿐만 아니라 일상생활과 연관된 온도, 습도, 대기압, 휘발성 유기화합물(VOC), 일산화탄소(CO), 아황산가스(SO₂), 이산화질소(NO₂), 소음을 센서의 응답 시간에 따라 최소 10초 간격으로 수집하였다. 수집된 정보들은 미세먼지 측정 디바이스 기준으로 반경 1km내 격자모양으로 지형 화면에 실시간으로 표시하고 모니터링함으로서 동작성을 확인하였다.

• 한국전기전자재료학회논문지
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• 제31권5호
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• pp.341-344
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• 2018

In order to achieve a high efficiency for the silicon solar cell, a passivation characteristic that minimizes the electrical loss at a silicon interface is required. In this paper, we evaluated the applicability of the oxide film formed by ozone for the tunnel silicon oxide film. To this end, we fabricated the silicon oxide film by changing the condition of ozone oxidation and compared the characteristics with the oxide film formed by the existing nitric acid solution. The ozone oxidation was formed in the temperature range of $300{\sim}500^{\circ}C$ at an ozone concentration of 17.5 wt%, and the passivation characteristics were compared. Compared to the silicon oxide film formed by nitric acid oxidation, implied open circuit voltage (iVoc) was improved by ~20 mV in the ozone oxidation and the ozone oxidation after the nitric acid pretreatment was improved by ~30 mV.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.406-406
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• 2016

To get high efficiency n-type crystalline silicon solar cells, passivation is one of the key factor. Tunnel oxide (SiO2) reduce surface recombination as a passivation layer and it does not constrict the majority carrier flow. In this work, the passivation quality enhanced by different chemical solution such as HNO3, H2SO4:H2O2 and DI-water to make thin tunnel oxide layer on n-type crystalline silicon wafer and changes of characteristics by subsequent annealing process and firing process after phosphorus doped amorphous silicon (a-Si:H) deposition. The tunneling of carrier through oxide layer is checked through I-V measurement when the voltage is from -1 V to 1 V and interface state density also be calculated about $1{\times}1012cm-2eV-1$ using MIS (Metal-Insulator-Semiconductor) structure . Tunnel oxide produced by 68 wt% HNO3 for 5 min on $100^{\circ}C$, H2SO4:H2O2 for 5 min on $100^{\circ}C$ and DI-water for 60 min on $95^{\circ}C$. The oxide layer is measured thickness about 1.4~2.2 nm by spectral ellipsometry (SE) and properties as passivation layer by QSSPC (Quasi-Steady-state Photo Conductance). Tunnel oxide layer is capped with phosphorus doped amorphous silicon on both sides and additional annealing process improve lifetime from $3.25{\mu}s$ to $397{\mu}s$ and implied Voc from 544 mV to 690 mV after P-doped a-Si deposition, respectively. It will be expected that amorphous silicon is changed to poly silicon phase. Furthermore, lifetime and implied Voc were recovered by forming gas annealing (FGA) after firing process from $192{\mu}s$ to $786{\mu}s$. It is shown that the tunnel oxide layer is thermally stable.

• 한국대기환경학회지
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• 제33권2호
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• pp.87-96
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• 2017

In this study, 4 gases containing typical chlorinated volatile organic compounds (VOCs) were treated by ultraviolet (UV) irradiation. The typical chlorinated VOCs are dichloromethane (DCM), trichloromethane (TCM), carbon tetrachloride (CTC) and trichloroethylene (TCE). The removal efficiency (RE) and the products of chlorinated VOCs by UV irradiation are investigated. At this time, 2 types of background gas (air and nitrogen) were used to figure out the RE by photooxidation and photolysis. The specification of UV-lamp used in this study was low-pressure mercury lamp emitting wavelength of 185~254 nm. The experimental conditions were set as initial VOC concentration of $180{\pm}10ppm$, empty bed retention time (EBRT) of 53 s, temperature of $23{\pm}2^{\circ}C$ and relative humidity of $65{\pm}5%$. In the photolysis condition with nitrogen ($N_2$) as background gas, the averaged RE of the 4 types of chlorinated VOCs was about 24% higher than that with photooxidation; and the REs of VOCs except CTC were confirmed as >99%. The composition of off-gases after UV photooxidation in air was investigated and several intermediates from DCM, TCM and TCE were detected by GC/MS. Among them, phosgene which is a toxics was detected as an intermediate of TCM. In addition, the concentration of carbon dioxide ($CO_2$) in the off-gases was measured to calculate the mineralization rate (MR). With the photooxidation, TCE showed the highest RE (>99%) while MR was the lowest (17%); and the MR of DCM was the highest (86%). In addition, particulate matters (PM) in the off-gases was also detected and high concentrated $PM_{10}$ ($21,580{\mu}g{\cdot}m^{-3}$) and $PM_{2.5}$ ($6,346{\mu}g{\cdot}m^{-3}$) were detected in TCE off-gas. More than 99% of the chlorinated VOCs could be removed using UV254-185 nm lamp, while it is necessary to conduct further studies on the production and treatment of secondary pollutants.

• Korean Chemical Engineering Research
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• 제50권1호
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• pp.149-154
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• 2012

바이오필터담체가 충전된 흡착칼럼 운전 시의 흡착 및 탈착거동에 대하여 조사하였다. 에탄올을 휘발성유기화합물(VOC)로서 함유하는 폐가스를 처리하기 위한 연속동적흡착 실험을 바이오필터공정과 같은 90% 이상의 상대습도에서 수행하였다. 에탄올 1,000 ppmv(or 2,050 mg ethanol/$m^3$)를 포함하는 폐가스 2 L/min을 흡착칼럼에 공급하였을 때에 흡착칼럼 출구에서의 파과점과 흡착평형에 이르는 시간은 1단 시료구에서 보다 각각 10배와 3배 만큼 지연되었다. 한편 에탄올 2,000 ppmv(or 4,100 mg ethanol/$m^3$)를 포함하는 폐가스의 경우에는 각각 9배와 3배 지연되었다. 이와 같이 흡착칼럼 출구에서 지연기간의 비는 공급농도와 무관하게 서로 거의 일치하였음이 관찰되었다. 또한 1단 시료구와 출구에서 비교한 유입폐가스의 에탄올농도의 10%를 보이는 탈착시간 지연비도 약 1.5배로서 거의 일치하였다. 한편 미생물활성과 멸균공정의 흡착평형에 대한 영향에 대하여 조사하였다. 멸균된 입상 활성탄으로 충전된 vial의 기상 에탄올 농도는 멸균되지 않은 입상 활성탄으로 충전된 경우와 거의 일치하였다. 그러나 퇴비(compost)나 입상 활성탄/퇴비 혼합물의 경우에는 멸균 안한 경우가 멸균한 경우보다 기상에서의 에탄올 농도가 현저하게 높았다.