• 대한기계학회논문집
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• 제14권5호
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• pp.1200-1210
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• 1990

본 연구에서는 먼저, 단열 압축기 또는 단열압축 과정에 대한 기존의 효율들, 즉 등 엔트로피 효율과 폴리트로픽 효율 및 엑서지 효율에서의 출력에 해당하는 양의 의미를 검토하고, 이들을 엑서지 출력을 일반화 시킨 형태의 일종으로서 설명하며, 기 타의 가능한 효율을 정의하고, 나아가 같은 논리를 압축과정 중 외부와 열교환이 있는 비단열 압축과정에 대하여 확장 적용시켜 비단열 압축과정에서의 열역학 제2법칙적 출 력 및 효율들을 정의하고 그들의 특성을 살펴보려 한다.

• 태양에너지
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• 제19권1호
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• pp.29-36
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• 1999

ZnO/n-Si junctions were fabricated by spin coating with ZnO precursor produced by the sol-gel process. In order to increase the electrical conductivity of ZnO films, the films were n-doped with Al impurity and subsequently annealed at about $450^{\circ}C$ under reducing environments. The ohmic contacts between n-Si and AI for a bottom electrode were successfully fabricated by doping the rear surface of Si substrate with phosphorous atoms. The front surface of the substrate was also doped with phosphorous atoms for improving the efficiency of the solar cells. Consequently, conversion efficiencies ranging up to about 5.3% were obtained. These efficiencies were found to decrease slowly with time because of the oxide films formed at the ZnO/Si interface upon oxygen penetration through the porous ZnO. Oxygen barrier layers could be necessary in order to prevent the reduction of conversion efficiencies.

• Korean Journal of Hydrosciences
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• 제5권
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• pp.71-83
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• 1994

The objectives of the paper are to apply the gross erosion and sediment delivery ratio method for estimating sediment deposits and to define their trap efficiencies. For twenty irrigation reservoirs which have sediment survey data, the gross erosion was estimated from the channel erosion as well as the soil losses by applying USLE. The gross erowion was reduced to the sediment yields by multiplying the sediment delivery ratios. The results were multipled by trap efficiencies after Brune method to estimate sediment deposits, which were compared to sediment surveyed data. The comparisons showed deposits. And a trap efficiency relationship was derived from a regression method, which appeared better suited for irrigation reservoirs.

• 한국IT서비스학회지
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• 제5권1호
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• pp.1-16
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• 2006

This paper analyzes the technical efficiencies of 40 Korean system integration firms using data envelopment analysis (DEA) and Malmquist productivity indices. Technical efficiencies on average had been decreased over the five year period and the efficiency difference between best practice firms and catch-up firms had been increased during this period, meaning that the industry structure has become matured and the possibilities for catch-up firms to be efficient are not remained so much. The differences in efficiency by the differences in ownership structures are statistically significant. It implies that the efficiencies of group-affiliated firms have come from benefits such as the captive market umbrellas, not from their own management competencies. In addition, the technical efficiency is highly correlated with captive market sales, information productivity, sales per employees, rates of value added, returns on invested capital, and EBITDA.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.183-183
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• 2018

In this study, 5-bromo-2,9-bis(5,6-diphenyl-1,2,4-triazin-3-yl)-1,10-phenanthroline (5-bromo-Ph4-BTPhen) was synthesized and evaluated for its ability to remove major radionuclides ($Cs^+$, $Sr^{2+}$, and $Co^{2+}$). The synthesized ligand removed both $Sr^{2+}$ and $Co^{2+}$ from $1mg\;L^{-1}$ aqueous solutions with extraction efficiencies of up to 99% at neutral and alkaline pH. The $Sr^{2+}$ and $Co^{2+}$ removal efficiencies decreased as a consequence of the higher bonding strengths of competing metal ions to the N-donor atoms in the cavity of the ligand; competing divalent ions affected the $Sr^{2+}$ and $Co^{2+}$ removal efficiencies more than monovalent ions.

• 한국물환경학회지
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• 제27권2호
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• pp.141-146
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• 2011

Loess, a natural clay, was evaluated as an adsorbent for the decolorization of Acid Orange II, an azo and reactive dye, from aqueous solution. Adsorption studies were performed at $30^{\circ}C$ and the effect of reaction time, loess dosage, initial concentration, loess particle size, pH, agitation rate were investigated to determine the optimum operation conditions. The removal efficiencies of color were measured to evaluate the effectiveness of loess. From this study, it was found that optimal reaction time was 10 min. Color removal efficiencies of Acid Orange II were increased as higher loess dosage, initial concentration and agitation rate. However, color removal efficiencies decreased when pH is high and loess particle becomes large. Adsorption of Acid Orange II fitted to the pseudo-second-order rate kinetics more than first-order rate kinetics. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of Acid Orange II onto loess fitted to the Freundlich model more than Langmuir model.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1471-1481
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• 2022

This paper aims to present a new method for obtaining an analytical solution for the Kaniadakis Doppler broadening (KDB) function. Also, in this work, we report the computational efficiencies of this solution compared with the numerical one. The solution of the differential equation achieved in this paper is free of approximations and is, consequently, a more robust methodology for obtaining an analytical representation of ψ_k. Moreover, the results show an improvement in efficiency using the analytical approximation, indicating that it may be helpful in different applications that require the calculation of the deformed Doppler broadening function.

• 한국해양환경ㆍ에너지학회지
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• 제7권3호
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• pp.116-121
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• 2004

고밀도 순환여과식 해산어 양식장의 순환수 처리에 EMMC공정의 적용 가능성을 평가하기 위한 실험을 실시하였다. 처리공정의 운전효율에 유기물 및 암모니아성 질소 부하가 미치는 영향을 평가하기 위하여 수리학적 체류기간을 12시간에서 10분까지 점차적으로 줄여가며 실험을 실시하였다. HRT 2시간까지는 수리학적 체류시간 변화에 따른 제거효율 변화가 거의 없었으나 그 이하의 체류시간에서는 체류시간 단축에 따른 제거효율의 감소가 비교적 크게 나타났다. COD의 경우에는 체류시간 단축에 따른 급격한 제거효율의 변화가 관측되지 않았으며 10분 정도의 체류시간에서도 90％이상의 제거효율을 나타내었다. 메디아 충진율에 따른 반응조 운전효율변화를 보면 HRT가 1시간보다 긴 경우에는 메디아 충진율에 따른 제거효율 변화가 극히 미미하였다. 그러나 1시간 이하의 체류시간에서는 그 차가 상당히 크게 나타나 충진량이 많을수록 제거효율이 높게 나타났으나 50％이상의 메디아 충진이 반응조 운전효율 측면에서는 큰 역할을 하지 못함을 나타내어 경제성 등을 고려할 경우 25％정도만을 충진 시키는 것이 오히려 합리적이라 판단되었다. 이와 같은 경향은 암모니아성 질소 제거의 경우에도 유사한 양상을 나타내었다. 메디아 충진율 50％와 75％사이에는 처리효율의 차이가 거의 없었고 25％충진 반응조와의 차이도 그리 크지 않은 것으로 나타났다.

• 한국산업보건학회지
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• 제34권1호
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• pp.48-56
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• 2024

Objectives: The coronavirus pandemic that began in 2019(COVID-19) has been one of the worst pandemics of the 21st century. Masks have been used to prevent COVID-19, but there are currently no standards for the long-term use of masks in the Republic of Korea. This study was conducted to assess the microbiological safety of KF94(Korea Filter 94) disposable face masks according to wearing duration by evaluating the bacterial filtration efficiencies of masks worn by research participants. Methods: A commercially available KF94 mask certified by the Ministry of Food and Drug Safety(MFDS) in the Republic of Korea was selected as the test mask. The research participants(n = 15) wore masks for the durations of one, three, and seven days. Participants also reported several parameters, including wearing time, makeup frequency, and storage. Bacterial filtration efficiencies of the worn masks were measured by a mask bioaerosol filtration tester. Staphylococcus aureus(S. aureus) was used as the test bacteria and quantitatively measured through the cultivation method. Then, bacterial filtration efficiency was calculated using the formula suggested by the MFDS. Results: All worn masks showed over 99.98% of mean bacterial filtration efficiency for S. aureus. There were no significant differences among bacterial filtration efficiencies of face masks according to wearing duration. There was also no significant difference among bacterial filtration efficiencies among participants. There was no correlation between the results of bacterial filtration efficiencies and reported parameters from participants. Conclusions: In the absence of significant external damage to the mask, the bacterial filtration efficiency of the mask can be maintained even after seven days of wearing. This result suggests that KF94 masks certified by the MFDS can be used repeatedly for about a week without loss of bacterial filtration efficiency.

• 한국환경보건학회지
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• 제28권5호
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• pp.1-3
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• 2002

This study was to evaluate on the removal efficiencies of total nitrogen and phosphorus in municipal wastewater at MUNR process using sludge carbon source for environmental micro-organism. The removal efficiencies of total suspended solid were 85.9~91％, total nitrogen were 38.6~87.2％ and total phosphorus were 30.8~39.0％, respectively. It was shown that removal efficiency of nitrogen was effectively influenced by sludge carbon source treated with ultrasonication. The removal efficiency of total phosphorus was low because the sludge was not wasted during this treatment.