• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.159-164
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• 1997

We have studied initial oxidation of the alkali metal(AM)/Si(111) surface using X-ray photoelectron spectroscopy(XPS) and reflection high energy electron diffraction(RHEED) at room temperature(RT) and high temperature(HT)(300~50$0^{\circ}C$). The oxidation of the Si(111)7$\times$7 surface was promoted by the adsorption of 1 momolayer(ML) AM, whereas no promotion occurred for submonolayer(<0.5 ML) adsorbed Si(111)7$\times$7 surface at RT. O Is core level spectra were measured with increasing oxygen exposure. It was found that the oxygen adsorbed on the Si(111)7$\times$7-AM surface have two different bond configuration, Si-O and Am-O, respectively. From these results, we discussed the role of AM-O bonding in the promoted oxidation. At HT(300~50$0^{\circ}C$), the AM-adsorbed surface became very inactive with the structural transformation to the 3$\times$1-AM. We present the results of the oxidation of the Si(111)3$\times$1-AM(Na, K, Cs) surface.

• Journal of Advanced Navigation Technology
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• v.22 no.3
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• pp.228-232
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• 2018

Dealing with quntization error in a control system properly becomes much more important as many devices are connected through network and controlled. Thus, in this paper, we study a data rate condition on quantizer to achieve practical stability in a discrete time linear time invariant system with state feedback control. First, required data rate is shown to depend on eigenvalue of the closed loop system, the size of the initial state vector, the magnitude of initial quantization error, and control gain in the absence of process noise. It additionally depends on the maximum magnitude of process noise when noise is not zero. Asymptotic analysis shows that a new design method may be needed to reduce the date rate for a networked control in the presence of quantization error and noise.. We provide a simple numerical evaluation of uniform quantizer and logarithmic qunatizer to assess their characteristics of practical stability depending on data rate in the presence of noise.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.1
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• pp.1-12
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• 2010

진단적 복강경을 하지 않으면 자궁내막증의 진단이 불가능하다는 점은 의사들이 해결해야 할 과제 중 하나이다. 아직까지는 자궁내막증을 진단할 수 있는 획기적인 표지자가 없기 때문에 CA-125 같은 종양 표지자의 혈중 농도를 측정하였으나 진단 도구로 이용하기에는 한계가 있다. 이러한 이유로 초기 자궁내막증을 진단할 수 있는 방법을 연구하기 위한 여러 시도들이 있었는데 특히 자궁내막증 1, 2기 환자에서 병의 초기 상태에 복강경적 치료를 하였을 경우 자연 임신 성공률이 2배 가까이 높은 것으로 보고되었기 때문에 불임 여성에 있어 자궁내막증의 진단 시기는 임상적으로도 그 중요성이 매우 크다고 할 수 있겠다. CA-125는 자궁내막증 환자의 추적관찰에 있어 특이도가 높은 편이며 효용성이 있는데 특히 수술적 치료 후 장기적으로 병의 활성 혹은 재발을 평가하는데 있어 유용하다. 무작위적인 임상 연구 결과 자궁내막증과 관련된 불임이나 통증은 수술적 치료시 분명한 이득이 있는 것으로 보고된 바84 자궁내막증은 적절한 진단과 치료가 중요한 질환이라는 점을 다시 한번 상기해야 한다. 또한 병의 진행에 따른 여러 면역학적인 변화들이 확인되면서 자궁내막증의 진단에 있어 면역학적 표지자의 중요성이 부각되고 있다. 그 중에서도 복막액이나 혈청 내 사이토카인은 진단 도구로서 그 가능성에 주목을 받고 있으며 이에 대한 대규모 연구가 추후 필요할 것으로 사료된다. 최근의 면역학적 발견과 DNA 기술 발전은 자궁내막증의 진단에 있어 핵심적인 screening 도구의 발견에 일조할 것이며 이러한 기술적 발전을 근간으로 하여 머지 않아 획기적인 표지자가 개발될 것으로 기대한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.1
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• pp.75-85
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• 1985

We have studied on the 2-D moving target tracking algorithm satisfying a real-time hardware implementation requirement. In this paper, a fast algorithm is developed based on the operator formulation and the variational algorithm f 10] . Here, we use the directed search for the maximum of the cross-correlation in order to obtain an initial estimate for the variational algorithm and decompose the scene into 16 smaller subblocks and apply the variational algorithm to each subblock sequentially with a new moving area detection method. We call the algorithm subblock based recursive algorithm. Compared with (10) , the ratio of the computational savings obtained from the proposed algorithm is 7 on the average.

• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.109-117
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• 1999

This paper describes the quick and precise control of the wafer temperature essential in rapid thermal processing(RTP). The bang-bang plus PID controller structure is introduced to satisfy rapid ramp-up rate and reduce overshoot and steady state error. The controller employs the PID action when the magnitude of the error between reference signal and the output temperature signal is smaller than some prescribed value. To find PID gains, the plant(autoregressive) model is first identified and Kappa-Tau tuning rule is used. The developed controller is applied to experimental RTP apparatus, and performances are evaluated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.3
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• pp.96-104
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• 2002

탄체가속기용 초기 발사장치로 사용 가능한 건국대 초고속 발사장치가 개발되었다. 이는 2단계 기포 (gas gun) 형태의 발사장치로 공기를 작동 기체로 사용하여 무게 22g의 탄체를 750m/sec로 가속할 수 있 는 성능을 보인다. 초고속 발사장치의 성능 특성을 알아보기 위하여, 구동부의 압축 특성과 작동 특성에 대한 성능 실험을 수행하였으며 실험으로부터 피스톤에 의한 압축 이득과 1,2차 구동부간에 발사장치의 성능을 최상으로 유지할 수 있는 값들이 존재함을 확인하였다. 초고속 비행체의 공력 특성 및 주위의 유동 해석에 응용 가능한 고속 탄환체에 대한 흐름의 가시화를 수행하여 수치적 계산 결과와 비교하였으며, 향후 고속유동의 물리적 현상 해석에 이용될 수 있음을 확인하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.664-672
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• 2010

This paper provides the target observability analysis of time-to-go polynomial guidance law with bearing-only measurement. In this study, a direct approach is used to analyze the target observability. Since the observability condition of a constant-velocity target is given by the function of LOS angle only, the target observability characteristic is determined by substituting the closed form solution of LOS angle to the observability condition directly. The analysis results show that the target observability is depended on the choice of guidance gain, initial intercept condition and guidance command shape. After that this mathematical analysis result is evaluated and demonstrated by number of simulation.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.299-308
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• 1998

In this paper, reliable switched reluctance motor(SRM) drive system and 4-rule based fuzzy logic modifier(FLM) of the conventional PI controller are presented. The i80C196KC, low-cost one-chip microcontroller is used for designing SRM drive controller which include the speed controller and the starting sequence. The fuzzy logic modifier which exhibits a stabilizing effects on the closed-loop system, has good robustness regarding the improperly tuned PI controller. The simulation and experimental results are performed to verify the capability of proposed control method on 6/4 salient type SRM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.2
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• pp.207-217
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• 1993

In this paper, knowing a priori probability of phase offset between transmitted codes and reference codes in the receiver, we construct the state diagram of acquisition process of the direct sequence spread-spectrum communication system using the expanding window search. The scannings are performed from the cell with higher probability code epoch synchronization to that with lower one. We expand window size from initial value by r times of its previous size in each search, construct the corresponding the state diagrams, and derive average synchronization time using the Markov process and Mason's gain formula. Average synchronization times versus number of search n and detection probability $P_d$ are calculated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.836-843
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• 2004

In per survivor processing (PSP) has a better performance than conventional phase offset estimators. But itsdefect is that it has a high complexity. In this paper, we propose the adaptive reduced state estimator (ARSE) algorithm not only to reduce the complexity, but also to have a good performance. The main principle of ARSE is changing the number of estimators dynamically during the decoding process according to the channel condition.