• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.379-382
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• 1997

A method for measuring optical properties of biological medium was investigated by using the frequency domain spectroscopy. When amplitude-modulated light with the frequency of several tens up to several hundred MHz propagates through a scattering medium, the phase lag and the amplitude reduction occur. The phase lag depends on the average of optical path lengths. The amplitude reduction with respect to the radial distance is influenced by the penetration depth. The mean of optical path length and penetration depth are related to optical coefficients. The phase lag and the amplitude reduction were measured based on the heterodyne detection method. The experimental data were fitted with the theoretical curves derived from diffusion theory and the absorption and scattering coefficients were calculated.

• 한국공작기계학회논문집
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• 제12권4호
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• pp.63-69
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• 2003

In discontinuous composite mechanics, shear lag theory is one of the most popular model because of its simplicity and accuracy. However, it does not provide sufficiently accurate strengthening predictions in elastic regime then the fiber aspect ratio is small. This is due to its neglect of stress transfer across the fiber ends and the stress concentrations that exist in the matrix regions near the fiber ends. To overcome this shortcoming, a more simplified shear lag model introducing the stress concentration factor which is a function of several variables, such as the modulus ratio, the fiber volume fraction, the fiber aspect ratio, is proposed. It is found that the modulus ratio($E_f$/$E_m$) is the essential variable among them. Thus, the stress concentration factor is expressed as a function of modulus ratio in the derivation. It is found that the proposed model gives a good agreement with finite element results and has the capability to correctly predict the values of interfacial shear stresses and local stress variations in the small fiber aspect ratio regime.

• Journal of Advanced Marine Engineering and Technology
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• 제34권7호
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• pp.951-962
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• 2010

An experimental study was performed to investigate the improvement of response performance of a turbocharged diesel engine under the operating conditions of low speed and fast acceleration. In this study, the experiment for improving the low speed and acceleration performance is performed by means of injecting air into the intake manifold of compressor exit during the period of low speed and application of a fast acceleration from low speed. The effects of air injection into the intake manifold on the response performance were investigated at various applicant parameters such as air injection pressure, accelerating rate, accelerating time, engine speed and load. The experimental results show that air injection into the intake manifold at compressor exit is closely related to the improvement of turbocharger lag under low speed and accelerating conditions of a turbocharged diesel engine. During the rapid acceleration period, the air injection into the intake manifold of turbocharged diesel engine indicates the improvement of the combustion characteristics and gas pressure in the cylinder. At low speed range of the engine, the effect of air injection shows the improvement of the pressure distribution of turbocharger and combustion pressure during the period of gas exchange pressure.

• 정보기술응용연구
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• 제3권2호
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• pp.25-48
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• 2001

최근 기업차원뿐 만 아니라 국가적 차원에서도 정보기술에 대한 투자 및 활용에 많은 노력을 기울이고 있다. 본 연구는 이러한 노력이 과연 가시적인 경제적 효과를 가져오는가를, 정보화수준과 생산성의 관계를 통해 알아보고자 한다. 특히, 거시적 차원에서 국가의 정보화수준이 국가경제생산성에 미치는 영향을 분석하기 위해, 주요 국가들의 정보화와 생산성에 관한 제반 통계자료를 수집하여 정보화지수 성장률과 총요소생산성(TFP : Total Factor Productivity) 및 노동생산성 성장률 등을 측정하고, 이들 개념간의 관계를 실증적으로 분석하였다.

• 정보화정책
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• 제29권3호
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• pp.26-47
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• 2022

'산업융합 신제품의 적합성 인증제도' (적합성 인증제도)는 개별 법령상에 융합 신제품에 적합한 인증 기준이 아직 준비되지 않았을 때, 별도의 입법 없이도 산업융합 촉진법에서 정한 바에 따라 동일 효력의 인증을 부여할 수 있는 법적 인증제도이다. 적합성 인증제도는 다른 인증제도들과 달리 규제 시차로 인한 융합 신제품의 인증애로를 해소하는 특성이 있다. 그럼에도 적합성 인증제도를 규제 개선의 관점에서 세부적으로 분석한 연구는 드물었다. 본 연구는 규제 문제가 발생 후 해소되기까지의 과정에 적합성 인증의 단계들을 순차적으로 매칭하여, 융합 신제품의 규제 시차가 적합성 인증의 절차를 통해 어떻게 감소되는지를 설명하였다. 나아가, 규제 시차 관리에 대한 관점을 정량적 측면과 정성적 측면으로 나누고, 규제 시차 감소를 위한 적합성 인증제도의 정량적·정성적 체계를 인증 절차의 각 단계별로 분석하였다. 이를 통해 본 연구는 적합성 인증제도가 융합 신제품의 규제 시차 문제를 해소할 수 있는 이유는 인증 절차별 법적 기한과 같은, 제도의 구조적 설계사항(정량적 측면) 뿐만 아니라, 개별 절차의 품질 확보를 위한 정성적 체계들을 갖추고 있기 때문임을 강조하였다.

• Journal of Microbiology
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• 제40권1호
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• pp.82-85
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• 2002

The aerobic batch growth of Issatchenkia orientalis DY252 with glucose and fructose medium was investigated at 32$\^{C}$ and pH 5.0. Aerobic ethanol production was evident with yeast I, orientalis. A diauxic lag of about 1 h between growth on glucose and growth on ethanol during batch culture was observed. However, no diauxic growth occurred with fructose. As the incubation temperature was increased from 32 to 39$\^{C}$, viability at the end of each batch culture declined significantly, from 93 to 43%, Unlike the effect of temperature, viability was not greatly affected by incubation pH, and cell yield values in a range of 0.45-0.48 were obtained. In order to overcome overflow metabolism, a fedbatch culture under glucose limitation was carried out. Compared with aerobic batch culture, about 10% improvement in cell yield was achieved with a fed-batch culture in optimal conditions.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.331-334
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• 2004

There are many researches investigating a causal relationship among service performance level, customer satisfaction, and customer loyalty. It is believed that a high service performance level increases customer satisfaction, which again has a significant effect on customer loyalty and profitability. The premise in this work is that the effect of customer satisfaction on customer loyalty may be time-lagged. This paper aims to model a causal relationship among service performance level, customer satisfaction, and customer loyalty with such a time-lag consideration. This study is conducted on the very high-speed digital subscriber lines service, which is a highly advanced high-speed internet service, and the results also be discussed.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.683-689
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• 2018

To evaluate equipment survivability of the polymer Viton, used in sealing materials, the effects of its thermal degradation were investigated in severe accident (SA) environment in a nuclear power plant. Viton specimens were prepared and thermally degraded at different SA temperature profiles. Changes in mechanical properties at different temperature profiles in different SA states were investigated. The thermal lag analysis was performed at calculated convective heat transfer conditions to predict the exposure temperature of the polymer inside the safety-related equipment. The polymer that was thermally degraded at postaccident states exhibited the highest change in its mechanical properties, such as tensile strength and elongation.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.252-261
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• 2013

In this paper, a nonlinear adaptive damping controller based on radial basis function neural network (RBFNN), which can infinitely approximate to nonlinear system, is proposed for thyristor controlled series capacitor (TCSC). The proposed TCSC adaptive damping controller can not only have the characteristics of the conventional PID, but adjust the parameters of PID controller online using identified Jacobian information from RBFNN. Hence, it has strong adaptability to the variation of the system operating condition. The effectiveness of the proposed controller is tested on a two-machine five-bus power system and a four-machine two-area power system under different operating conditions in comparison with the lead-lag damping controller tuned by evolutionary algorithm (EA). Simulation results show that the proposed damping controller achieves good robust performance for damping the low frequency oscillations under different operating conditions and is superior to the lead-lag damping controller tuned by EA.

• 대한음성학회지:말소리
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• 제52호
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• pp.15-48
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• 2004

The present study investigates phonation types of the plosives in Bahasa Indonesia in terms of VOT, F0, durations of intervocalic closure, the preceding vowel, and the following vowel. The results showed that two speaker groups have distinct phonation types. Speaker Group I was characterized by a short voice lag for voiceless plosives and a considerable amount of voice lead for voiced ones. Speaker Group II was characterized by a short lag for both voiceless and voiced plosives. Although both groups showed a significant difference in F0 and the durations of individual segments between voiceless and voiced plosives, they had a remarkable difference in the temporal structure of the segments. Speaker Group I had temporal compensation between the intervocalic closure and the surrounding vowels across voice, such that the shorter the intervocalic closure the longer the surrounding vowels, while Speaker Group 2 didn't. This means that there are two different phonation type systems within a language.