• Journal of Drive and Control
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• v.12 no.1
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• pp.1-8
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• 2015

The stability of friction characteristics and thermal management for a dry type dual clutch transmission (DCT) are inferior to those of a wet clutch. Too high temperature resulting from frequent engagement of DCT speeds up degradation or serious wear of the pressure plate or burning of the clutch disk lining. Even though it is significantly important to estimate the temperature of a dry double clutch (DDC) in real-time, few meaningful study of the thermal model of DDC has been known yet. This study presented a thermal analytical model of lumped parameters for a DDC by analyzing its each component firstly. Then a series of experimental test was carried out on the test bench with a patented temperature telemetry system to validate the proposed thermal model. The thermal model, whose optimal parameter values were found by optimization algorithm, was also simulated on the experimental test conditions. The simulation results of DDC temperature show consistency with the experiment, which validates the proposed thermal model of DDC.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.625-633
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• 2011

Characteristics of a commercial metal hydride (MH) hydrogen supply system have been investigated and an operating strategy was developed based on the experimental data. As a prior step, charging/discharging capacity, thermal properties such as heat capacity, heat of reaction of MH system were experimentally measured. And then P-C-T data for various operating conditions were collected and a correlation between P, C and T predicting the behavior of MH was derived. Based on the basic experimental data, an operating strategy of MH system was developed, in which the hot water temperature supplied into the water jacket of MH was controlled depending on the pressure of MH, thereby the pressure of MH could be maintained at a suitable range. By adjusting the temperature of hot water from $40^{\circ}C$ to $60^{\circ}C$, the maximum discharging capacity of hydrogen could be increased by 4.7%, and consequently more stable hydrogen supply and longer operation time of fuel cell system could be achieved.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.115-122
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• 2010

The importance of the life cycle cost (LCC) analysis for bridges has been recognized over the last decade. However, it is difficult to predict LCC precisely since the costs occurring throughout the service life of the bridge depend on various parameters such as design, construction, maintenance, and environmental conditions. This paper presents a methodology for the optimal life cycle cost design of a bridge. Total LCC for the service life is calculated as the sum of initial cost, damage cost, maintenance cost, repair and rehabilitation cost, user cost, and disposal cost. The optimization method is applied to design of a bridge structure with minimal cost, in which the objective function is set to LCC and constraints are formulated on the basis of Korean Bridge Design Code. Initial cost is calculated based on standard costs of the Korea Construction Price Index and damage cost on damage probabilities to consider the uncertainty of load and resistance. Repair and rehabilitation cost is determined using load carrying capacity curves and user cost includes traffic operation costs and time delay costs. The optimal life cycle cost design of a bridge is performed and the effects of parameters are investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.448-454
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• 2009

Hydrogen was produced from water plasma excited in high frequency (HF) inductively coupled tubular reactor. Mass spectrometry was used to monitor gas phase species at various process conditions, Water dissociation rate depend on the process parameters such as ICP power, $H_{2}O$ flow-rate and process pressure, Water dissociation percent in ICP reactor decrease with increase of chamber pressure, while increase with increase of ICP power and $H_{2}O$ flow rate. The effect of $CH_4$ gas addition to a water plasma on the hydrogen production has been studied in a HF ICP tubular reactor. The main roles of $CH_4$ additive gas in $H_{2}O$ plasma are to react with 0 radical for forming $CO_x$ and CHO and resulting additional $H_2$ production. Furthermore, $CH_4$ additives in $H_{2}O$ plasma is to suppress reverse-reaction by scavenging 0 radical. But, process optimization is needed because $CH_4$ addition has some negative effects such as cost increase and $CO_x$ emission.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.639-642
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• 2003

This paper presents a method for evaluating the mixed nash equilibria of the Cournot model for N-Gencos. in wholesale electricity market. In the wholesale electricity market, the strategies of N-Genco. can be applied to the game model under the conditions which the Gencos. determine their stratgies to maximize their benefit. Generally, the Lemke algorithm is evaluated the mixed nash equlibria in the two-player game model. However, the necessary condition for the mixed equlibria of N-player are modified as the necessary condition of N-1 player by analyzing the Lemke algorithms. Although reducing the necessary condition for N-player as the one of N-1 player, it is difficult to and the mixed nash equilibria participated two more players by using the mathmatical approaches since those have the nonlinear characteristics. To overcome the above problem, this paper presents the generalized necessary condition for N-player and proposed the object function to and the mixed nash equlibrium. Also, to evaluate the mixed equilibrium through the nonlinear objective function, the Particle Swarm Optimization (PSO) as one of the heuristic algorithm are proposed in this paper. To present the mixed equlibria for the strategy of N-Gencos. through the proposed necessry condition and the evaluation approach, this paper proposes the mixed equilibrium in the cournot game model for 3-players.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.6-7
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• 2008

Current sensing in power semiconductors involves sensing of over-current in order to protect the device from harsh conditions. This technique is one of the most important functions in stabilizing power semiconductor device modules. The sense FET is very efficient method with low power consumption, fast sensing speed and accuracy. In this paper we have analyzed the characteristics of proposed sense FET and optimized its electrical characteristics to apply conventional 450V power MOSFET devices by numerical and simulation analysis. The proposed sense FET has the n-drift doping concentration $1.5\times10^{14}cm^{-3}$, size of $600{\mu}m^2$ with 4.5 $\Omega$, and off-state leakage current below 50 ${\mu}A$. We offer the layout of the proposed sense FET to process actually. The offerd design and optimization methods is meaningful, which the methods can be applied to the power devices having various breakdown voltages for protection.

• KSBB Journal
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• v.16 no.4
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• pp.365-369
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• 2001

Chitinase producing microorganism, Serratia marcescens KY, was isolated from seashore mud around Beobseongpo in Chunnam province by selective enrichment culture. As the colloidal chitin concentration increased, chitinase production was increased. But chitinase production with addition of other carbon sources (glucose, fructose, galactose, maltose, sucrose, starch) was decreased. The effect of nitrogen sources on the chitinase production with serratia marcescens KY was as fellows. The opitimum mineral concentration for chitinase production was K$_2$HPO$_4$ 0.2 g/L and MgSO$_4$ 0.20 ∼ 0.25 g/L, respectively. The effect of nitrogen sources on chitinase production by Serratia marcescens KY was increased as follows, tryptone > yeast extract > beef extract > asparagine.

• KSBB Journal
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• v.19 no.2
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• pp.148-153
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• 2004

Lipase catalyzes the hydrolysis of glycerides into fatty acids and glycerol. The study of microbial lipases has been stimulated in resent years. It is due to the potential uses of lipases in esterification of oils to glycerol, alcohols and carbohydrates. Development of lipase producing yeast has been focused concerning to the utilization of yeast culture for animal feed. In this study, yeast like cells was isolated from a waste oil and sludge. A strain having higher lipase activity was selected by random mutagenesis using UV-radiation. The optimal cultivation conditions in submerged culture were examined in terms of lipase production. 2.0％ of high fructose syrup, 1,0％ of CSL, and 1.0％ of olive oil were selected as the nutritional media for the production of lipase. The maximum lipase activity of 1.12 U/ml and viable cell number of 8.8${\times}$10$\^$7/ cells/mL were obtained at 27$^{\circ}C$ with an initial pH of 5.0.

• KSBB Journal
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• v.28 no.1
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• pp.42-47
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• 2013

This study was performed to find cellulolytic strain of enzymatic saccharification for bioethanol production. Cellulolytic strains were isolated from 59 different feces of herbivores from Seoul Grand Park located in Gwacheon Gyeonggi-Do. The celluloytic strain was selected by congo red staining and DNS method. Among the isolated strains, H9-1 strain isolated from the feces of rabbit has the highest CMCase activity. H9-1 strain was identified as Bacillus sp. based on 16S rDNA gene sequencing. The optimal conditions for CMCase activity by Bacillus sp. H9-1 were at $40^{\circ}C$ and at initial pH 8.

• Korean Journal of Construction Engineering and Management
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• v.18 no.1
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• pp.83-89
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• 2017

Temporary structures provide the accessible working area when building a permanent building structure in the construction operation. Executed in a natural environment, the temporary structure is prone to the external influence factors of underground water, soil conditions, etc. These factors should be carefully considered in designing the temporary structure. The objective of this study is to apply the external influence factors in designing a more reliable earth retaining wall. The research methodology is based on the Taguchi method that has been studied to improve product quality in the industry. An orthogonal array was developed to analyze the interaction between the external influence factors and the internal influence factors. A sample case study demonstrated that the Taguchi method can be used in planning a more reliable temporary structure for earth retaining walls.