• 한국통신학회논문지
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• 제27권4C호
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• pp.371-379
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• 2002

본 논문에서는 동작주파수 범위가 DC에서부터 3GHz인 MMIC SPST(Single Pole Single Throw) 스위치를 설계 및 제작하였다. 스위치 회로 설계에 앞서 성능을 정확히 예측하기 위하여 스위치 소자의 소신호 및 대신호 모델이 필요하며, 새로이 제안된 스위치 소자의 소신호 등가회로 모델 파라미터들은 측정된 5-파라미터로부터 최적화 기법을 사용하여 추출하였다. 이때 예측된 초기값과 경계구간을 사용함으로써 최적화 기법이 가지고 있는 문제점을 보완하였다. 대신호 모델은 측정된 DC 데이터로부터 경험식의 파라미터들을 추출함으로써 전류원을 모델링하였고, 드레인-소오스간 바이어스 전압을 변화시켜 측정한 5-파라미터로부터 채널 커패시턴스 값을 추출함으로써 전하 모델을 도출하였다. 이를 초고주파 회로 시뮬레이터에 적용하여 일반적인 직렬-병렬구조의 SPST 스위치와 격리도를 개선한 SPST 스위치를 설계하였으며, 개선된 SPST 스위치 경우 3GHz의 동작주파수에서 0/-3V의 컨트롤 전압을 인가하머 측정한 결과 삽입손실은 0.302dB, 격리도는 35.762dB, 입출력 VSWR은 각각 1.249와 1.254이며, PldB는 약 15.7dBm이다.

• 한국미생물·생명공학회지
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• 제24권2호
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• pp.206-212
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• 1996

The strain producing bioemulsifier was isolated from soil samples. The isolated strain was identified as the genus Acinetobacter through its morphological, cultural and physiological characteristics. The highest emulsification activity and stability by Acinetobacter sp. BE-254 was observed after 5 days of cultivation in the culture medium containing n-hexadecane 4%, NaNO$_{3}$ 0.2%, KH$_{2}$PO$_{4}$ 0.01%, MgSO$_{4}$-7H$_{2}$O 0.01%, CaCl$_{2}$ 0.01%, and yeast extract 0.01%. The optimum pH and temperature for bioemulsifier production were pH 7.0 and 30$\circ$C, respectively. Furthermore the most of bioemulsifier was produced during the exponential growth phase, and this suggested that the bioemulsifier production was growth-associated. The bioemulsifier showed good emulsification activity on various emulsifying substrates such as hydrocarbons, edible oils, and petroleum fractions.

• 센서학회지
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• 제20권4호
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• pp.254-259
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• 2011

In this paper, a current stimulator circuit with adaptive supply regulator for retinal prosthesis is proposed. In current stimulation systems, the stimulating circuits with wide voltage swing range are needed due to the high impedance of the retina cell and microelectrodes. Thus, previous researches adopt the high voltage architecture to obtain the enough operating range. The high voltage architecture, however, could increase the power consumption and can damage the retina cells. The proposed circuit provides the adaptively regulated supply voltage by measuring the difference between desired stimulation current and the actual stimulation current. The proposed circuit can achieve the extended range of the allowable cell impedance, improved accuracy of the stimulation current, and higher biosafety.

• Bulletin of the Korean Chemical Society
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• 제17권3호
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• pp.254-257
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• 1996

Nucleophilic substitution reactions of 1- and 2-naphthylethyl arenesulfonates, 2 and 3, with anilines and benzylamines in methanol at 65.0 ℃ are investigated. The rates are slower than those for the corresponding derivatives of 2-phenylethyl arenesulfonates, 1, which can be attributed to a greater degree of positive charge stabilization at Cα in the transition state (TS) by a greater electron supply from a phenyl ring compared to a naphthyl ring. The mechanism for the two naphthylethyl systems are similar to that for the 2-phenylethyl derivatives, except that the transition state is formed at somewhat an earlier position along the reaction coordinate. The secondary kinetic isotope effects involving deuterated nucleophilies indicate that naphthylethyl series are sterically more crowded in the TS than 2-phenylethyl system. The data in this work can not elucidate the possible participation of the aryl-assisted pathway in the reaction.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.250-254
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• 1998

This paper shows how the environmental parameters(temperature, humidity) in the greenhouse are influenced by air movement produced by air circulation fans. When the fans were used, they could make indoor temperature and humidity homogenious, but there was no significant difference in the location and number of fans. When the fans were not used during the night time, there was no significant difference in the temperature and humidity, but the standard deviation was reduced by using the fans.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.254-255
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• 2011

This paper presents a method to analysis the effect for integrating Sihwa tidal power into power systems. Especially, power flow, fault current, voltage and contingency of sihwa tidal power plant area are calculated and the generation characteristics of tidal machine are analyzed.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.251-254
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• 2003

For improving the flow capacity of pipeline system the hydraulic inspection method was developed conducting on-site with survey of pipeline facility such as diversion work, air vent, etc. and pipe network analysis. The pipe network analysis method determine pipe diameter with trial and error. The validity of the hydraulic inspection method proved adapting on S-district pipeline system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.252-254
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• 2007

In this paper, we will introduce an encoding algorithm of LDPC Codes in Direct-Sequence UWB systems. We evaluate the performance of the coded systems in an AWGN channel. This new algorithm is based on the Jacket matrics. Mathematically let A = ($a_{kl}$) be a matnx, if $A^{-1}$ = $(a^{-1}_{kl})^r$,then the matrix A is a Jacket matrix. If the Jacket matrices if Low density, the inverse matrices is also Low density which is very important to the introduced encoding algorithm.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 춘계학술논문발표회 논문집
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• pp.251-254
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• 2008

The fact that the major cases of life casualties are from smoke in the fire accidents and the expected steep increase of skyscrapers, huge spaces, multiplexes and huge scaled underground spaces demand establishment of efficient smoke countermeasure. The field experiments on two high buildings of 20 stories and 21 stories are carried out to evaluate the field performance of pressure differential systems for smoke management and the results of experiments are presented.

• 대한치과보철학회지
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• 제29권1호
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• pp.249-254
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• 1991

Two male patients of hereditary ectodermal dysplasia with oligodontia aged 12years and 10years 6months were recalled after 6 years and treated by reconstructing overdentures according to the growth. Patients were improved functionally and cosmetically. Periodic recall is reguired and denture should be reconstructed according ato their growth.