• 설비공학논문집
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• 제25권4호
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• pp.201-207
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• 2013

The performance of automobile air conditioning systems of R1234yf was evaluated and compared with that of R134a. In particular, the performance evaluation was carried out by installing an internal heat exchanger in order to improve the performance of the system used in R1234yf. A performance comparison between the R1234yf and R134a for automotive air conditioning revealed that the cooling capacity and COP of the 1234yf system without the IHX decreased by up to 7% and 4.5%, respectively, but those with the IHX decreased by up to 1.8% and 2.9%, respectively.

• 상하수도학회지
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• 제11권1호
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• pp.74-80
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• 1997

The objectives of this study were to compare the characteristics of water quality in alternative Aerobic-Anoxic(A/A) and Aerobic(Control) sludge digestion. The A/A process control parameter as the pH signal(dpH/dt) was used. Comparison of the result of A/A digestion with those of Aerobic digestion indicated a 54% saving in aeration compared to Aerobic digestion. TN removal efficiency rates of A/A and Aerobic digestion were 45% and 4%, respectively. The concentration of COD(64 mg/l and 268 mg/l for the A/A and Aerobic digestion, respectively) and Ortho-P in the supernatant were also less with A/A digestion. MLVSS and Coliform destructions were noticed similar for both digestion, but better dewatering charateristics were noted for the A/A digestion.

• 한국응용과학기술학회지
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• 제27권1호
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• pp.37-43
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• 2010

The objective of this study was to evaluate the antifungal properties of xanthorrhizol (extract from curcuma xanthorrhiza) against Candida albicans. Some of the commercial products were evaluated for their ability to inhibit growth of C. albicans. OTC product containing povidone iodide and cosmetic grade product with surfactants were tested. Antifungal activity was shown in 1.56% of OTC product, however, there was no antifungal effect in cosmetic product. For the comparison, we tested several materials. Povidone iodide, lemon tea tree oil and xanthorrhizol showed antifungal activities against C albicans in 0.25, 0.062 and 0.007%, respectively. We also tested the antifungal effects of povidone iodide and xanthorrhizol in surfactant base. Test results revealed that 2.5% of povidone iodide and 0.156% of xanthorrhizol showed similar antifungal effects. These findings support the application of xanthorrhizol for vaginal cleanser or personal cares using antifungal effect.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.573-575
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• 2000

For the greenhouse gas emissions' reduction of fossil fuel, the energy policy on promotion of alternative energy should be implemented. Accordingly, national policies on the development and promotion of alternative energy were made and related laws and regulations are being made and comprehensive plans should be followed. The policies and strategies for promoting the renewable energy have been insufficient in comparison with that of the developed countries. This paper suggests the optimal subsidy level for Photovoltaic and Wind Power.

• 한국분무공학회지
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• 제13권2호
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• pp.65-72
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• 2008

It is recognized that alternative fuel such as dimethyl ether (DME) has better combustion polluting characteristics than diesel fuel, even though the cetane number of DME is almost the same as that of diesel. Characteristics of DME spray were observed experimentally under various ambient conditions using a constant volume chamber and a common-rail injection system. N-dodecane and LPG fuel sprays were also observed under same conditions of DME spray. Using spray images from backlight scattering and Mie scattering, characteristics of fuel sprays such as penetration and spray volume were visualized and quantitatively measured. The measurements showed that the penetration of early period decreased remarkably, because evaporation of alternative fuels became prosperous by the influence of flash boiling phenomenon under the condition of the low temperature and pressure compared with n-dodecane. The penetration of DME and LPG spray received the influence of temperature more largely in comparison with low density, because the specific surface area increased by atomizing in high density.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2006년도 PROCEEDINGS OF JOINT CONFERENCEOF KDISS AND KDAS
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• pp.181-187
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• 2006

대규모 표본조사와 관련해서 관심변수와 보조변수간의 약한 상관관계를 고려한 Amahia et al.(1989)의 대체추정방법을 Rao-Hartley-Cocharn 추출방법에 적용해서 Rao추정량과 효율성을 비교 하였다.

• 한국산업융합학회 논문집
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• 제16권2호
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• pp.29-33
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• 2013

This study has been conducted to propose an optimal design guidance of underfloor air distribution system by examining air pattern and proper exhaust status of floor plenum using CFD (Computational Fluid Dynamics). Simulation shows deficient air pattern and exhaust status at BPG (Bypass Grille) of the current design. As a means to find an alternative design, four cases have been developed and tested. Case 1, 2 and 3 show similar results in comparison to the current design. However, case 4 shows improved air pattern and exhaust status at BPG(Bypass Grille), and has been chosen as the optimal alternative.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.16-21
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• 2003

Natural gas is one of the promising alternative fuels because of the abundant deposits and the cleanness of emission gas. It can be used in conventional gasoline engine without major modification. Natural gas has some advantages than gasoline i.e. the high octane number, good mixing condition because of gas and wide inflamable limit. In the present study, a $1.8{\ell}$ conventional gasoline engine is modified for using the CNG as a fuel instead of gasoline. Performance and emission characteristics are compared between gasoline and CNG with 4 cylinder SI Engine which is controlled by programable ECU. Parameters of experimentation are equivalence ratio, spark timing and fuels. We analyzed the combustion characteristics of the engine using the cylinder pressure i.e. ignition delay, combustion duration and cycle variation. As a result, CNG engine shows lower exhaust emissions but brake torque is slightly reduced compared to gasoline engine. Overall combustion duration is longer than that of gasoline because of lower burning speed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.199-209
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• 1998

Since most engineering problems have had open-ended and ill-defined characteristics, design process is in advance attended with determination of alternatives based on realistic constraints after definition of appropriate problem. And it is completed with selection of best alternative through their comparison and investigation, and with performance of selected-alternative's detail design. As the process of structural design compared with that of general design, this paper presents a paradigm which can generate structural design alternatives, select optimum structure among them and simultaneously set its optimum design variables in reference of several objective as a result in more extended design region. For this purpose, specialized genetic algorithms which can handle design alternatives and multicriteria problems is used.

• 한국식품영양학회지
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• 제9권4호
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• pp.490-495
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• 1996

홑파래로부터 황산기를 함유한 다당체를 크로마토그래프로 분리정제하여 rhamnan sulfate가 항보체 활성화에 미치는 영향을 조사하였다. 항보체 활성능력은 F-4-3 획분을 비교군으로 Heparin H-180, Dextran과 비교해 결과 비교군보다 높았고, C4a와 C3a의 C convertase의 형성과 기능을 F-4-3 획분이 억제하였다. 이러한 보체 활성화 양식은 classical pathway 및 alternative pathway로도 경유함을 알 수 있었다.