• Journal of Life Science
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• v.17 no.11
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• pp.1517-1522
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• 2007

Gap junction channels formed by two adjacent cells allow the passage of small molecules up to ${\sim}\;1\;kDa$ between them. Hemichannel (connexon or half of gap junction) also behaves as a membrane channel like sodium or potassium channels in a single cell membrane. Among 26 types of connexin (Cx), $Cx32^*43E1$ (a chimera in which the first extracellular loop of Cx32 has been replaced with that of Cx43), Cx38, Cx46, and Cx50 form functional hemichannels as well as gap junction channels. Although it is known that Xenopus oocytes express endogenous connexin 38 (Cx38), its biophysical characteristics at single channel level are poorly understood. In this study, we performed single channel recordings from single Xenopus oocytes to acquire the biophysical properties of Cx38 including voltage-dependent gating and permeation (conductance and selectivity). The voltage-dependent fast and slow gatings of Cx38 hemichannel are distinct. Fast gating events occur at positive potentials and their open probabilities are low. In contrast, slow gatings dominate at negative potentials with high open probabilites. Based on hi-ionic experiments, Cx38 hemichannel is anion-selective. It will be interesting to test whether charged amino acid residues in the amino terminus of Cx38 are responsible for voltage gatings and permeation.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.119.1-119.1
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• 2016

크라이오 워터펌프(CWP)는 크라이오 펌프(CP)와 달리 10 K 활성탄 어레이는 장착하지 않고 100 K 정도로 냉각시킨 배플만을 사용하여 물의 배기속도를 최적화 하는 데 초점을 맞춘 진공펌프다. 용기 압력이 10-9 mbar 대가 될 때까지는 잔류기체의 90% 이상이 수분이므로 다른 기체들의 배기 보다는 물을 잘 배기하는 것이 배기시간을 단축하고 도달 진공도를 낮추는 첩경이라는 아이디어에 근거를 두고 있다. CWP는 물 흡착확률을 거의 1에 가깝게 만들어서 오리피스 컨덕턴스에 육박하는 이상적인 펌프를 제작할 수 있지만 용도상 직부형(close type), 통과형(in-line type) 및 내장형(in-vessel type) 등 세 가지 다른 형태에 따라 성능도 약간씩 다르다. CWP는 모든 기체에 반응하는 정통적인 CP에 비해 훨씬 간단하고 저렴하게 만들 수 있으면서도 진공 시스템에 큰 영향을 미칠 수 있지만 물 이외의 기체들을 배기할 펌프가 필요하다는 측면에서 활용에 제약이 있다. 만일 TMP를 이미 사용하고 있거나 작은 TMP를 추가로 달아서 충분히 작동이 가능한 시스템이면서 수분 발생이 많은 곳이나, 또 활성탄의 오염이나 산소 분위기 등 CP 투입이 꺼려지는 환경이라면 CWP 사용이 좋은 선택이 될 수 있다. CWP의 물 배기용량은 CP의 알곤이나 질소 배기용량에 준하는 크기로 0.5g/cm2 이상임이 실험적으로 입증되었다. 따라서 일반적인 상황에서 정상 작동시 대부분의 기체는 TMP로 배출하고 잔류 수분만 포집하므로 CP처럼 주기적인 재생이 필요 없다. 필요하다면 CWP는 금속 표면에 응축된 물을 드라이펌프 작동만으로 쉽게 제거할 수 있고 혹시 오염 물질이 붙어도 세척이 용이하다. 이런 사용상 융통성과 여러 가지 장점에도 불구하고 그동안 물배기에 대한 인식이 미흡하고, 또 부수적이고 추가적인 비용이 드는 것으로 생각되어 주목을 받지 못했지만 디스플레이와 반도체 산업을 필두로 물 분압을 낮추고 생산수율을 높이는 것에 점점 더 관심이 높아지면서 CWP에 대한 수요도 높아지고 있다. 본 보고에서는 20인치 통과형 CWP를 만들고 14인치 TMP에 얹어 복합 진공배기시스템을 구성한 후 물 배기속도와 알곤, 질소 및 수소 배기속도를 측정하고 예측치와 비교했다. 아울러 물 배기용량 측정 및 CWP의 온도제어와 펌프재생 특성 평가 결과도 정리했다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10A
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• pp.969-979
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• 2002

This paper proposes an novel method of minimizing Interference which causes data decision error in digital wireless communications. In this method, in order to suppress ISI which is caused by the phase difference between the transmitted and received signal phases, the transmitted and received signals are always kept orthogonal by compensating the transmitted signal for detecting the phase noise and the delay of the received signal was implemented by MOS circuits. To delay the phase of the signal, additive white Gaussian noise (AWGN) environment was used. The phase and delay of the signal transmitted through AWGN channel were compensated in the modulator of the transmitter and the compensated signal was demodulated using quasi-direct conversion receiver and QPSK demodulator. ISI suppression was achieved by keeping the orthogonality between the compensated transmitted signal and the receive signal. The error probability of data decision was compared. By simulation the proposed system was proved to be effective in minimizing the ISI.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1234-1243
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• 1992

A systematic procedure to design fuzzy PID controllers is developed in this paper. The concept of local fuzzy control cell is proposed by introducing both an adequate global control rule and membership functions to simplify a fuzzy logic controller. Fuzzy decision is made by using algebraic product and parallel firing arithematic mean, and a defuzzification strategy is adopted for improving the computational efficiency based on nonfuzzy micro-processor. A direct method, transforming the typical output of quasi-linear fuzzy operator to the digital compensator of PID form, is also proposed. Finally, the proposed algorithm is applied to an DC-servo motor. It is found that this algorithm is systematic and robust through computer simulations and implementation of controller using Intel 8097 micro-processor.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.5
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• pp.171-180
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• 2003

CDMA(Code Division Multiple Access) mobile communication systems require accurate channel estimation in the receiver to compensate the fading distortions. Instantaneous channel estimates are obtained by dividing the received symbol by the transmitted symbol and then refined by filtering to reduce the estimation variance. In the channel estimation filter, the determination of the filter size is a very important task which greatly affects the estimation quality. While conventional methods usually use only velocity estimators to determine the channel estimation filter size, this paper proposes a filter size determination method for decision-directed channel estimators considering the symbol error rate and the signal-to-noise ratio in addition to the velocity of the mobile station. This paper shows that the symbol error rate and the signal-to-noise ratio are important factors for the determination of the channel estimation filter size.

• Journal of Korean Society of Disaster and Security
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• v.8 no.1
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• pp.39-46
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• 2015

This study is concerned with the estimation of fluctuation wind velocity spectrum and turbulence characteristics in the major cities reflecting the recent meteorological with typhoon wind velocity about 2003 (Maemi) 2010 (Kompasu) 2012 (Tembin). The purpose of this paper is to present spectral analysis for longitudinal component fluctuating velocity obtained by Monte Carlo Simulation method. In the processes of analysis, the longitudinal velocity spectrums are compared widely used spectrum models with horizontal wind velocity observations data obtained at Korea Meteorological Adminstration (KMA) and properties of the atmospheric air for typhoon fluctuating wind data are estimated to parameters with turbulency intensity, shear velocity, probability distribution and roughness length.

• Communications for Statistical Applications and Methods
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• v.19 no.2
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• pp.277-286
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• 2012

For credit assessment models, the ROC curves evaluate the classification performance using two univariate cumulative distribution functions of the false positive rate and true positive rate. In this paper, it is extended to two bivariate normal distribution functions of default and non-default borrowers; in addition, the bivariate ROC curves are proposed to represent the joint cumulative distribution functions by making use of the linear function that passes though the mean vectors of two score random variables. We explore the classification performance based on these ROC curves obtained from various bivariate normal distributions, and analyze with the corresponding AUROC. The optimal threshold could be derived from the bivariate ROC curve using many well known classification criteria and it is possible to establish an optimal cut-off criteria of bivariate mixture distribution functions.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.48-61
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• 2020

The objective of this study is to estimate traffic capacity based on the heavy-vehicle ratio in a two-lane freeway work zone where one lane is blocked by construction. For this, closed circuit television (CCTV) video data of the freeway work zone was collected, and the congestion at an upstream point was observed. The traffic volume at a downstream point was analyzed after a bottleneck was created by the blockage due to the upstream congestion. A distribution model was estimated using observed-time headway, and the road capacity was analyzed using a goodness-of-fit test. Through this process, the general capacity and an equation for capacity based on the heavy-vehicle ratio passing through the work zone were presented. Capacity was estimated to be 1,181~1,422 passenger cars per hour per lane (pcphpl) at Yeongdong, and 1,475~1,589pcphpl at Jungbu Naeryuk. As the ratio of heavy vehicles increased, capacity gradually decreased. These findings can contribute to the proper capacity estimation and efficient traffic operation and management for two-lane freeway work zones that block one lane due to a work zone.

• Journal of Korean Society of Disaster and Security
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• v.8 no.1
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• pp.29-37
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• 2015

This study is concerned with the estimation of fluctuation wind velocity spectrum and turbulence characteristics in the major cities reflecting the recent meteorological with typhoon wind velocity about 2003 (Maemi) 2010 (Kompasu) 2012 (Tembin). The purpose of this paper is to present spectral analysis for longitudinal component fluctuating velocity. In the processes of analysis, the longitudinal velocity spectrums are compared widely used spectrum models with horizontal wind velocity observations data obtained at Korea Meteorological Adminstration (KMA) and properties of the atmospheric air for typhoon fluctuating wind data are estimated to parameters with turbulency intensity, shear velocity and roughness length.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1234-1243
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• 1994

We propose an adaptive decoding scheme for a concatenated codes with frequency-hopped spread-spectrum communication system in the presence of a pulse-burst jammer and its performance is analyzed. Concatenated coding system employing binary inner code and Reed-Solomon outer code is investigated and the use of side information is allowed to decode both erasures and errors. Our scheme makes the decoder adapts to the level of jamming by switching between two decoding modes such that the overall block error probability can be reduced. It is shown that the proposed decoding scheme yields a significant performance improvement over a conventional decoding scheme.