• 한국수소및신에너지학회논문집
• /
• 제17권4호
• /
• pp.409-417
• /
• 2006

The characteristics of hydrogen-oxygen mixture gas generation stack was experimentally studied in terms of efficiency. For this purpose, the mixture gas generation stack was fabricated by connecting 7 cells in series following the Tero Ranta report. In order to avoid the instrument inaccuracy, all measuring equipments were re-tested and calibrated by Korea Laboratory Accreditation Scheme (KOLAS) certified laboratories. Since the amount of produced gas is most crucial in determining the efficiency, two gas collecting methods such as bottle trap method and wet gas meter method were adopted. From the experimental results, it was found that both KOH fume and steam evaporated along with hydrogen-oxygen mixture gas, and these by-product gases could cause the misestimation of the stack efficiency. The current, voltage, and energy efficiencies of the hydrogen-oxygen mixture gas generation stack was evaluated based upon the stack efficiency calculation method summarized in this work.

• 한국응용곤충학회지
• /
• 제36권1호
• /
• pp.105-110
• /
• 1997

Fenvalerate, cypermethrin, furathiocarb 및 prothiofos에 대해 각각 581, 18, 19, 11배의 저항성을 보인 진주계통과 fenvalerate와 furathiocarb에 대해 각각 38배와 9배의 저항성을 나타내고 있는 함양.서상계동을 bifenthrin과 prothiofos의 혼합조합으로 방제하기 위해 실내 엽침지법과 포장방제시험을 수행하였다. Bifenthrin 1EC와 prothiofos 50EC을 1:50으로 혼합하여 실내엽침지법으로 처리하였을 때 공력계수가 273.2로 최고점에 도달한 후 급격히 감소하는 양상을 보였다. 침지법에서 가장 효과적이었던 혼용비율의 조합을 함양.서상현지 농가에서 실증시험을 수행한 결과, 처리구에서 처리약량을 절반으로 줄였음에도 배추좀나방의 방제효과가 농가관행구와 마찬가지로 우수하였다. 또한 이 조합은 여러가지 대표적인 살충제에 대해 높은 저항성을 나타내고 있는 진주지역계통에 대해서도 합리적인 농약혼합으로 저항성문제에 적절히 대처할 수 있음을 보여주었다.

• 한국식품영양학회지
• /
• 제14권1호
• /
• pp.20-27
• /
• 2001

십자화과 식물인 무(Raphanus sativus L.)의 어린싹(무순)이 독특한 향과 맛으로 소비가 증가하고 있는바 그 향기성분을 SDE(simultaneous steam disti-llation/extraction) 법과 P&T(purge and cryogenic trapping)법으로 추출하여 비교, 분석하였다. 향기성분 포집시 SDE법에서는 diethyl ether 및 diethyl ether-pentane mixture(2:1, v/v)를 용매로 사용하고 P&T법에서는 diethyl ether를 사용하였다. GC와 GC-MS를 사용하여 동정한 결과 diethyl ether로 추출한 SDE법에서는 함황화합물(19종, 76.6%)이 주성분이었고, diethyl ether-pentane mixture로 추출한 경우 함황화합물(15종, 44.0%)과 탄화수소류(23종, 23.8%)가 주성분이었으며, P&T법으로 추출할 경우는 탄화수소류(25종, 84.1%)가 주성분이었다. 또한 신선한 무순의 주 향기성분은 hydrocarbon류인 n-heptane, methyl pentane이었으며, 익은 무순의 주 향기성분은 sulfur compound에 속하며 무의 주성분이기도 한 4-methylthio-3-butenyl isothiocyanate, methyl mercaptane, 2,3-dimethyl disulfide 등이었다. SDE법 보다 P&T법에 의해 추출할 경우 향기성분의 종류와 상대적인 양은 적어 분리능은 떨어지는 편이나 저분자 휘발성 물질은 오히려 더 많이 검출되어 추출방법에 따라 포집되는 향기성분의 종류와 양에 차이가 있었다.

• 한국자동차공학회논문집
• /
• 제12권2호
• /
• pp.32-38
• /
• 2004

This study was performed to investigate the behavior of liquid and vapor phase of fuel mixtures with different piston cavity diameters in a optically accessible engine. The conventional engine was modified as Central Injected DI gasoline engine with swirl motion. Two dimensional spray fluorescence images of liquid and vapor phase were acquired to analyze spray behavior and fuel distribution inside of cylinder using exciplex fluorescence method. Piston cavity geometries were set by Type S, M and L. The results obtained are as follows. In the spray formation after SOI, the cone angle and width of the spray were decreased at late injection timing. With a fuel injection timing of BTDC $180^{\circ}C$, fuel was not greatly affected in a piston cavity but generally distributed as homogeneous mixture in the cylinder. With a fuel injection timings of BTDC $90{\circ}C$ and $60^{\circ}C$, fuel mixture was widely distributed in near the cavity center. As a injection timing was late in the compression stroke, residual width of fuel mixture was narrow in proportion to piston cavity.

• 한국도로학회논문집
• /
• 제17권4호
• /
• pp.33-40
• /
• 2015

PURPOSES: Evaluation of the wind speed effect on the temperature drop of an asphalt mixture during construction, by using the transient heat transfer theory and dominant convective heat transfer coefficient model. METHODS: Finite difference method (FDM) is used to solve the transient heat transfer difference equation numerically for various wind speeds and initial temperature conditions. The Blasius convective heat transfer coefficient model is adapted to account for the effect of wind speed in the temperature predictions of the asphalt mixture, and the Beaufort number is used to select a reasonable wind speed for the analysis. As a function of time and depth, the temperature of the pavement structure is predicted and analyzed for the given initial conditions. RESULTS : The effect of wind speed on the temperature drop of asphalt mixture is found to be significant. It seems that wind speed is another parameter to be accounted for in the construction specifications for obtaining a better quality of the asphalt mixture. CONCLUSIONS: It is concluded that wind speed has a significant effect on the temperature drop of the asphalt layer. Although additional field observations have to be made to reflect the effect of wind speed on the construction specifications, it appears that wind speed is a dominant variable to be considered, in addition to the atmospheric temperature.

• Journal of the Optical Society of Korea
• /
• 제20권1호
• /
• pp.199-203
• /
• 2016

An enzyme-free optical method is proposed for estimating high concentrations of glucose in a glucose-lactose mixture, based on a predictive equation that takes advantage of the reflective optical power observed at two discrete wavelengths. Compared to the conventional absorption spectroscopy method based on Beer's Law, which is mainly valid for concentrations below hundreds of mg/dL, the proposed scheme, which relies on reflection signals, can be applied to measure higher glucose concentrations, of even several g/dL in a glucose-lactose mixture. Two probe wavelengths of 1160 and 1300 nm were selected to provide a linear relationship between the reflective power and pure glucose/lactose concentration, where the relevant linear coefficients were derived to complete the predictive equation. Glucose concentrations from 2 to 7 g/dL in a glucose-lactose mixture were efficiently estimated, using the established predictive equation based on monitored reflective powers. The standard error of prediction was 1.17 g/dL.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제13권3호
• /
• pp.186-199
• /
• 2013

We pose pattern classification as a density estimation problem where we consider mixtures of generative models under partially labeled data setups. Unlike traditional approaches that estimate density everywhere in data space, we focus on the density along the decision boundary that can yield more discriminative models with superior classification performance. We extend our earlier work on the recursive estimation method for discriminative mixture models to semi-supervised learning setups where some of the data points lack class labels. Our model exploits the mixture structure in the functional gradient framework: it searches for the base mixture component model in a greedy fashion, maximizing the conditional class likelihoods for the labeled data and at the same time minimizing the uncertainty of class label prediction for unlabeled data points. The objective can be effectively imposed as individual mixture component learning on weighted data, hence our mixture learning typically becomes highly efficient for popular base generative models like Gaussians or hidden Markov models. Moreover, apart from the expectation-maximization algorithm, the proposed recursive estimation has several advantages including the lack of need for a pre-determined mixture order and robustness to the choice of initial parameters. We demonstrate the benefits of the proposed approach on a comprehensive set of evaluations consisting of diverse time-series classification problems in semi-supervised scenarios.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
• /
• pp.487-492
• /
• 1999

The purpose of this study to find the mixture of concrete for Top-Down method. Throughout test of elapsed time change and L-type flow, it was proposed basic performance and level of top-down method concrete. When change as to elapsed time is considered, so series of F10 added 10% S.P satisfied slump and demanded flow (60$\pm$5cm), and L-type slump, L-type flow satisfied liquidity, it can be considered basic mixture of designed actual frame later.

• 한국분말재료학회지
• /
• 제10권1호
• /
• pp.6-14
• /
• 2003

The purpose of the present study is to investigate the method decreasing debinding time as well as lowering operation condition than pure supercritical $CO_2$ debinding by using cosolvent or binary mixture of propane + $CO_2$. First method is to add cosolvent, such as n-hexane, DCM, methanol, 1-butanol, in supercritical $CO_2$. In case of adding cosolvent, we were found the addition of non-polar cosolvent (n-hexane) improves dramatically the binder removal rate (more than 2 times) compared with pure supercritical $CO_2$ debinding, second method is to use mixture of supercritical propane + $CO_2$, as solvent. In case of using mixture of supercritical propane + $CO_2$, the rate of debinding speeded up with increasing of pressure and concentration of propane at 348.15 K. It was found that addition of cosolvent (e.g., n-hexane, DCM) and binary mixture propane + $CO_2$ for supercritical solvent remarkably improved binder removal rate for the paraffin wax-based binder system, in comparison with using pure supercritical $CO_2$.

• 한국산학기술학회논문지
• /
• 제13권3호
• /
• pp.1002-1007
• /
• 2012

Pillar의 제조 방법은 진공유리 및 반도체 디스플레이 분야에서 사용되는 핵심공정 중 하나이다. Pillar는 스크린 인쇄 방식을 통하여 배치할 수 있으나 시료의 성분에 따라 메탈마스크의 패턴을 전부 통과하지 못하거나 점도에 따라 통과된 혼합물이 본래의 형상을 유지 못하는 경우가 발생한다. 본 연구에서는 알루미나와 실리카 기반의 무기화합물을 이용하여 스크린 인쇄를 통해 pillar를 배치하였다. 실험계획법의 하나인 혼합물 설계를 이용함으로써 실험횟수를 줄이고 진공유리 pillar의 조성을 설계할 수 있는 방법을 제시하고자 한다.