• Journal of the Korean Society of Combustion
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• v.13 no.1
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• pp.10-16
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• 2008

Numerical simulations of freely propagating premixed flames burning mixtures of methane and chlorinated hydrocarbons in fuel are performed at atmospheric pressure in order to understand the effect of chlorinated hydrocarbons on the formation of nitrogen oxide. A detailed chemical reaction mechanism is used, the adopted scheme involving 89 gas-phase species and 1017 elementary forward reaction steps. Chlorine atoms available from chlorinated hydrocarbons inhibit the formation of nitrogen oxides by lowering the concentration of radical species. The reduction of NO emission index calculated with thermal or prompt NO mechanism is not linear and is probably related to the saturation effect as $CH_3Cl$ addition is increased, In the formation or consumption of nitrogen oxide, the $NO_2$ and NOCl reactions play an important role in lean flames while the HNO reactions do in rich flames. The molar ratio of Cl to H in fuel has an effect on the magnitude of NO emission index.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11b
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• pp.969-973
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• 2003

지리적으로 분산되어 있는 이기종의 분산 컴퓨팅 자원과 대규모 데이터를 효과적으로 활용하기 위해서 최근에 GRID 컴퓨팅 환경에 대한 연구가 매우 활성화되고 있다. 이러한 GRID 환경을 구현하기 위해 필요한 부분중의 하나가 사용자와 자원간의 인증에 관련된 문제이다. 현재 Globus Toolkit은 PKI(Public Key Infrastructure)를 기본으로 하는 보안정책을 사용하고 있다. 이 정책은 인증과정에 적지않은 오버헤드가 발생되는 문제점을 가지고 있다. 이에 본 논문에서는 사용자와 자원간의 직접적인 인증으로 인해 발생하는 성능상의 비효율성을 줄이기 위해 사용자가 자원에 접속 하기전 AIS서버(Authentification Information Server)를 이용하여 미리 인증을 거친후, 자원에 접근한 때는 기 발급된 식별자로 인증 될 수 있도록 처리해주는 메커니즘을 제안한다.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.35-38
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• 2005

This paper suggests the method that forecast Dynamic Line Rating (DLR). Thermal Overload Risk (TOR) of next time is forecasted based on current weather condition and DLR value by Monte Carlo Simulation (MCS). To model weather element of transmission line for MCS, we will propose the use of weather forecast system and statistical models that time series law is applied. Also, through case study, forecasted TOR probability confirmed can utilize by standard that decide DLR of next time. In short, proposed method may be used usefully to keep safety of transmission line and reliability of supply of electric Power by forecasting transmission capacity of next time.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.1
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• pp.78-84
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• 2002

This paper is a study for the computerization program of incoming and outgoing processes of a number of parts and a great amount of material for producing products in flood industry, which was required by a medium-sized company located at Cheon-An. The program consists of four databases, one main form, seventeen subforms, and eight report forms. Concretely speaking, the four databases are prepared for products, semi-products, material, and reports, and the seventeen subforms are those for current inventory, used quantity, safty stock, product specification, etc. With the program, users can be helped and save manpower, time and cost in incoming and outgoing processes of parts and material for producing products and in their real time operation and decision-making.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1459-1461
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• 1999

Distribution systems is consist of network in physical aspect, and radial in electrical aspect. Therefore, radial operation is realized by changing the status of sectionalizing switches, and is usually done for loss reduction in the system. In this paper, we propose a optimal method for distribution systems reconfiguration. Specifically, we use K-optimal algorithm and tabu search method to solve distribution systems reconfiguration for loss minimization problem.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.45-48
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• 2003

In general, speech coding methods are classified into the following three categories: the waveform coding, the source coding and the hybrid coding. Fast speaking is possible to encode with a few information compared with slow speaking rate. In case of speaking rate, low frequency band is more important than high frequency band while listening. Speech vocoding technique is developing to way with low bit rate and complexity and high sound quality. the CELP type of vocoder support very good sound quality with low bit rate but these vocoders don't consider about the speaking rate. When we consider speaking rate and encode the frame depending on the speaking rate, the bit rate is able to reduce the bit rate than the conventional vocoder. We propose the technique to estimate the speaking rate and applied PSOLA technique in case of the frame of slow speaking rate. As a result of simulation bit rate can be reduced about 300 bps.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2005.11a
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• pp.82-83
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• 2005

Recently, layer industry shows the decrease in the number of farm and increase in rearing scale in both Korea and Japan. Seventy percent of layer farms in Japan feed more than 50,000 birds per each farm but in Korea, only 19.3% of layer farms are feeding more than 30,000 birds which covers 59% of total chicken number. This tendeney will be more accellerated from now on. Brand egg Production in Japan is developed with the involvement of farmers, sailers feed companies and also the marketing structure of brand egg is well organised in between farmers and consumers. However in Korea, the marketing structure of brand egg is not well settled for this reason the egg price is often decided lower much price than regrnlar price by the intermediate dealers. Under this kind of tough situation, Korean layer farmers are stressed to develop new brand products such as functional egg, settle the sales and distribution network with the good cooperation of farmers, and distributers.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.24-27
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• 1999

IMBE(Improved Multi-Band Excitation) vocoders exhibit good performance at low data rates. The major drawback to IMBE coders is their large computational requirements. In this paper, thus, we propose a new pitch search method that preserves the quality of the IMBE vocoder with reduced complexity. The basic idea is to skip unnecessary range of the pitch searching by using the quantization error. Applying the proposed method to the IMBE vocoder, we can get approximately $45.88\%$ processing time reduction and there is no difference in voice quality between conventional IMBE and proposed IMBE.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.1131-1134
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• 1999

In general CELP type vocoders provide good speech quality around 4.8kbps. Among them, G.723.1 developed for Internet Phone and videoconferencing includes two vocoders, 5.3kbps ACELP and 6.3kbps MO-MLQ. Since 6.3kbps MP-MLQ requires large amount of computation for fixed codebook search, it is difficult to realize real time processing. In order to improve the problem this paper proposes the new method that reduces the processing time up to about 50% of codebook search time. We first decide the grid bit, then search the codebook. Grid bit is selected by comparison between synthetic speech, which is synthesized with only odd or even pulses of target vector. and DC removed original speech. As a result, we reduced the total processing time of G.723.1 MP-MLQ up to about 26.08%. In objective quality test 11.19㏈ of segSNR was obtained, and in subjective quality test there was almost no speech degradation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.61
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• pp.59-73
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• 2000

Nowadays many People know well that happiness depends not on richness but on health and wellbeing, and many researchers have studied about such subjects. This paper studies correlations, causal relations and factors of many variables to be considered to be able to explain human health and welfare in a country system, using Kendall's tau and factor analysis methods. Also it finds what main variables are to be controlled for a country system to become more advanced in various sides of health and welfare, using Mann-Whitney statistics. The contribution of this paper is that it can suggest essential variables and important relations which are helpful to construct an efficient system of health and welfare in Korea.