• 대한전기학회논문지:전력기술부문A
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• 제52권11호
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• pp.668-674
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• 2003

The electric marketplace is in the midst of major changes designed to promote competition. No longer vertically integrated with guaranteed customers and suppliers, electric generators and distributors will have to compete to sell and buy electricity. Unit commitment (UC) in such a competitive environment is not the same as the traditional one anymore. The objective of UC is not to minimize production cost as before but to find the solution that produces a maximum profit for a generation firm. This paper presents a hi-level formulation that decomposes the UC game into a generation-decision game (first level game) and a state(on/off)-decision game (second level game). Derivation that the first-level game has a pure Cournot Nash equilibrium(NE) helps to solve the second-level game. In case of having a mixed NE in the second-level game, this paper chooses a pure strategy having maximum probability in the mixed strategy in order to obviate the probabilistic on/off state which may be infeasible. Simulation results shows that proposed method gives the adequate UC solutions corresponding to a NE.

• Archives of Pharmacal Research
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• 제2권1호
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• pp.35-47
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• 1979

In order to increase the dissolution rate of furosemide(4-choro-N-furfury1-5-sulfamoy1 anthranilic acid_, various ratio coprecipitates with water-soluble polymers, such as polyvinylpyrrolidone and polythylene glycol, of different molecular weight, were prepared and quantitatively studied by comparing their dissolution characteristics of furosemide at powder state and at nondisintegrating disk state containing constant surface area at various temperatures and rotating velocities. The dissolution characteristics of furosemide from pure furosemide disks and 1:2(w/w) furosemide-PVP coprecipitate disks were in accordance with Noyes-Nernst equation and the rate constant of dissolution was proportional to the square root of rotating velocity of the disks. The intrinsic rate of dissoluton at 150 rpm, 37.deg.C was $2.21{\times}10^{-7}$ for the PVP 10, 000 COPRECIPITATE, $1.64{\times}10^{-7}$ for the PVP 40, 000 coprecipitate, and$ 1.44 {\times} 10^{-7}$for the PVP 360, 000 corprecipitate, while the rate was $1.27{\times}10^{-8}M/cm^{2} min$ for pure furosemide, repectively. The activation energy of dissolution was about 17, 000 for furosemide and about 7, 300 cal/mole for the 1:2 furosemide PVP 40, 000 coprecipitate, respectively.

• 한국가스학회지
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• 제10권1호
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• pp.38-42
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• 2006

본 연구에서는 순수한 프로판 냉매를 사용하여 액화석유가스(LPG)를 액화 및 냉동 저장할 수 있는 냉동 사이클에 대한 모사기법을 소개하였다. 프로판을 액화시키기 위한 2차 냉매로써는 물을 사용하였다. 전체 냉동 사이클의 모사를 위한 열역학 모델로서는 Peng-Robinson 상태방정식을 사용하였다. 프로판 성분과 LPG구성성분의 증기압의 좀 더 정확한 추산을 위하여 Twu 등이 제안한 새로운 alpha function을 사용하였다. 또한 액상의 밀도를 정확하게 추산하기 위해서는 Peng-Robinson상태방정식 대신에 API모델식을 사용하였다. 모사를 위하여 Simulation Science사의 PRO/II with PROVISION version 7.1 범용성 화학공정 모사기를 사용하였다 본 연구를 통하여 국내에서 실제로 가동되고 있는 LPG 저장을 위한 냉동 사이클을 성공적으로 모사할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.185-188
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• 2002

This paper describes the information for quantitative simulation of weakly ionized plasma. We should grasp the meaning of the plasma state condition to utilize engineering application and to understand materials of plasma state. In this paper, the drift velocity of electron in $SF_6+O_2$ mixture gas calculated for range E/N values l~900[Td] at the temperature is 300[$^{\circ}K$] and pressure is 1[Torr], using a set of electron collision cross sections determined by the authors and the values of drift velocity of electrons are obtained for TOF, PT, SST sampling method of Backward Prolongation by two term approximation Boltzmann equation method. It has also been used to predict swarm parameter using the values of cross section as input. The result of Boltzmann equation, the drift velocity of electrons, has been compared with pure $SF_6$, pure $O_2$ and mixture gas.

• Applied Biological Chemistry
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• 제4권
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• pp.23-28
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• 1963

1. 등전씨(藤田氏)의 Ether-alkali partition extraction법(法)을 개량(改良)하여 Capsaicin을 순수(純粹)하게 분리(分離)하여 정량표준곡선(定量標準曲線)을 얻었다. 2. Soxhlet장치(裝置)를 사용(使用)하여 Ether-Acetone(3:1) 혼합용매(混合溶媒)로 Capsaicin을 추출(抽出)한 후(後) 58% Methanoldmf 전개제(展開劑)로 하는 paper partition chromatography에 의(依)하여 불순물(不純物)로부터 Capsaicin을 순수(純粹)하게 분리(分離)하였다. 3. Diazobenzenesulphonic acid를 발색제(發色劑)로 사용(使用)하는 Schulte-Kruger 변법(變法)에 약간(若干) 개량(改良)을 가(加)하여 각품종별(各品種別) 고추중(中) Capsaicin 함량(含量)을 측정(測定)하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.137-137
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• 2003

Conducting PPy/PVA composite and pure PPy gas sensors were prepared by in-situ vaporstate polymerization method in a vaporization chamber under N2 condition, by exposing the pre-coated electrode with PVA/FeC13 to distilled pyrrole monomer. The various electrical sensing behaviors of both types of sensors were systematically investigated by a flow measuring system including mass flow controller (MFC) and bubbling bottle. The FT-Raman spectroscopy of vapor state polymerized PPy was identical to that of chemically polymerized PPy, confirming the same chemical structure. Both types of sensors had positive sensitivity when exposed to methanol gas. The sensitivity varied linearly with gas concentration in the range of 50ppm to 1059ppm. The detection limit of PPy/PVA sensor was believed to be as low as 10ppm. The sensitivity of PPy/PVA composite sensor was higher than that of pure PPy sensor. Both the response time and recovery time of PPy/PVA composite sensors were longer than those of pure PPy sensors. The thickness of the sensing film affected the sensitivity this way that the sensor having thinner film had higher sensitivity, indicating that the resistance of polymer film involved in the sensing behavior was bulk resistance rather than surface resistance. The reproducibility of PPy/PVA composite sensor was excellent during eight on-off cycles by switching between N2 and 3000ppm methanol gas. The sensitivity of PPy/PVA composite sensor was only maintained for two weeks, while the sensitivity of pure PPy sensor was maintained over two months.

• 한국분말재료학회지
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• 제25권2호
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• pp.99-103
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• 2018

Spherical monosized pure aluminum (Al) particles are successfully fabricated by the pulsated orifice ejection method (POEM). The surface reaction between Al and the graphite crucible is investigated by analysing the microstructure and chemical composition of the materials. No significant chemical reaction occurs between Al and the graphite owing to the crystalline Al oxide (${\gamma}-Al_2O_3$) layer generated in the initial state. The ${\gamma}-Al_2O_3$ layer is clearly observed in all regions between the Al particles and graphite via transmission electron microscopy and confirmed by the selected area diffraction pattern. The morphology of the ${\gamma}-Al_2O_3$ layer perfectly follows the surface morphology of the graphite crucible, which showed nanoscale roughness. This implies that molten Al could not directly contact graphite even though the surface of the crucible became rough to some extent. However, this passivation phenomenon allowed the successful fabrication of monosized pure Al particles. Therefore, POEM is a useful process at least to manufacture monosized pure Al particles.

• 전기학회논문지
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• 제66권1호
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• pp.153-158
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• 2017

This paper investigates a robust low-complexity design problem for tracking control of uncertain switched pure-feedback systems in the presence of unknown control direction. The completely unknown non-affine nonlinearities are assumed to be arbitrarily switched. By combining the nonlinear error transformation technique and Nussbaum-type functions, a robust tracking controller is designed without using any adaptive function approximators. Thus, compared with existing results, the proposed control scheme has the low-complexity property. From Lyapunov stability theory, it is shown that the tracking error remains within the preassigned transient and steady-state error bounds.

• 대한기계학회논문집
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• 제18권4호
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• pp.1019-1030
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• 1994

Natural convection heat transfer from a horizontal ice cylinder immersed in quiescent cold pure water was studied experimentally. The experiment was conducted for the ambient water temperatures ranging from $2.0^{\cric}C$ to $10.0^{\circ}C$. The flow fields around an ice cylinder and its melting shapes were visualized and local Nusselt numbers obtained. Especially, its attention was focused on the density maximum effects and stagnation point Nusselt number. From the visualized photographs of flow fields, three distinct flow patterns were observed with the ambient water temperature variation. The melting shapes of ice cylinder are various in shape with flow patterns. Steady state upflow was occured at the range of $2.0^{\circ}C \leq T_{\infty} \leq 4.6^{\circ}C$ and steady state downflow was occured at $T_{\infty} \geq 6.0^{\circ}C$. In the range of $4.7^{\circ}C < T_{\infty} < 6.0^{\circ}C$, three-dimensional unsteady state flow was observed. Especially, the melting shapes of ice cylinder have formed the several spiral flutes for the temperatures ranging from $5.5^{\circ}C$ to $5.8^{\circ}C$. For upflow regime, the maximum stagnation point Nusselt number exists at $T_{\infty} = 2.5^{\circ}C$ and as the ambient water temperature increases the Nusselt number decreases. At ambient water temperature of about $5.7^{\circ}C$, Nusselt number shows its minimum value.

• Preventive Nutrition and Food Science
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• 제2권1호
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• pp.66-70
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• 1997

A mixed-culture of Gluconobacter suboxydans IFO 3172 and Saccharomyces uvarum IFO 0751 was per-formed in a synthetic medium. the optimal inculum ratio of G. suboydans and S. uvarum for mixed-culture fermentation was 150:1. The optimum pH, incubation temperature and aeration rate for mixed-culture fer- mentation were 5.0, 3$0^{\circ}C$ and 2.25vvm, reapectively. As a result of batch pure-and mixed-culture fer-mentation, specific growth rate in pure-culture of both strain was lower than that in mixed-culture. The yield of cell mass from S. uvarum exclusively decreased. The growth rate of the mixed-culture was very similar to the pure-culture in the begining of culture, but it has been decreased after 16hrs. In the mean time, S. uvarum in mixed-culture fermentation could grow due to fructose converted, but it could not row in pure-culture fermentation. Thus, the relationship was a sort of commensalism. The kinetic parameters cal-culated through steady-state results during continuous fermentations are as follows :{TEX}$$\mu$_{max1}${/TEX}=0.118({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{1}${/TEX}=0.330(g/L),:{TEX}$$\mu$_{max2}${/TEX}=0.162({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{2}${/TEX}=0.038(g/L). The yield of bacterial cell mass relatively constant, but yield of yest cell mass was gradually decreased.