• 전자공학회논문지A
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• 제32A권12호
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• pp.209-219
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• 1995

As a new algorithm for RC tree delay estimation, we propose a $\tau$-model of the driver and a moment propagation method. The $\tau$-model represents the driver as a Thevenin equivalent circuit which has a one-time-constant voltage source and a linear resistor. The new driver model estimates the input voltage waveform applied to the RC more accurately than the k-factor model or the 2-piece waveform model. Compared with Elmore method, which is a lst-order approximation, the moment propagation method, which uses $\pi$-model loads to calculate the moments of the voltage waveform on each node of RC trees, gives more accurate results by performing higher-order approximations with the same simple tree walking algorithm. In addition, for the instability problem which is common to all the approximation methods using the moment matching technique, we propose a heuristic method which guarantees a stable and accureate 2nd order approximation. The proposed driver model and the moment propagation method give an accureacy close to SPICE results and more than 1000 times speedup over circuit level simulations for RC trees and FPGA interconnects in which the interconnect delay is dominant.

• Journal of Power Electronics
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• 제18권5호
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• pp.1479-1488
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• 2018

Power packet (PP) distribution system distributes power to different loads that share the same distribution cable in a packetized form. When compared with conventional power systems, a PP distribution system (PPDS) can reduce standby power, eliminate Point-of-Load (PoL) power conversion, and intelligently control the load demand from the source side. Due to the absence of PoL conversion, when multiple power sources at different voltage levels and conditioning requirements jointly send power to various loads at different voltage ratings, the generated voltage has an irregular shape. A large filter at each of the load sides is required to reduce such a large voltage ripple. In this paper, a single-inductor, multiple-input-single-output converter structure based multiple-energy-source mixer is proposed. It combines PP generation, maximum power point tracking (MPPT) of renewable energy sources (RESs) and filtering at the source side. To demonstrate the possible renewable energy integration, a PV panel is used as a power source together with other constant voltage sources. The PV power is approximately tracked using the constant voltage method and it is used for each of the PP generations. The proposed PP distribution system is experimentally verified and it is shown that a conventional PI controller is sufficient for stable system operation.

• 한국환경과학회지
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• 제24권3호
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• pp.353-358
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• 2015

In this study, we analyzed two types of echolocation calls used by the parti-coloured bat, Vespertilio sinensis. Bats were captured in the Naejangsan National Park in October 2013. Call sounds of hand-released bats were recorded at the location of capture within the National Park. We analyzed pulse duration (PD), pulse interval (PI), peak frequency (PF), maximum frequency ($F_{MAX}$), minimum frequency ($F_{MIN}$), and bandwidth (BW). V. sinensis emitted the different types of the echolocation calls depending on the surrounding environment. Frequency modulated-constant frequency (FM-CF) signal of audible range was emitted when they flew in the uncluttered space over the canopy. However, when flying in the cluttered space below the canopy, they only emitted FM signal. FM-CF signal is in the audible range (e.g., low frequency), and FM signal has a harmonic broadband frequency range of two. There were significant differences in PD, PI, PF, FMAX, FMIN, and BW between the calls emitted over and below the canopy. Considering the functional characteristics of FM and CF signals, we conclude that the foraging activity of V. sinensis was observed below the canopy, and recommend the use of FM signal and broadband as echolocation signals.

• 대한화학회지
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• 제37권1호
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• pp.148-153
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• 1993

진한 황상 용액에서 4'-halogenated azoxybenzene 유도체의 Wallach 자리옮김 반응을 UV-Vis 분광학적 방법으로 재조사하였다. 흥미롭게도 log(rate)와 pi 비편재화 파라미터라 불리우는 치환체 상수, ${\sigma}_R{^+}$와의 도시에서 아주 좋은 직선관계$(logk_{obs}=-0.61\;{\sigma}_R{^+} -3.29,\;{\gamma = 0.998)$를 얻었다. 그 겨로가로 공명효과에 의해 크게 안정화될 수 있는 즉 + 전하를 가진$(DC^{++})$중간체를 거치는 B-L 메카니즘이 Wallach 재배열 반응에 더욱 강력히 주장된다.

• 대한화학회지
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• 제37권5호
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• pp.503-512
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• 1993

역상 액체 크로마토그래피를 이용하여 페놀류를 효과적으로 분리-분석하는데 기본적으로 필요한 용리거동을 조사하고, 이를 바탕으로 머무름을 예측하는데 이 연구의 목적을 두었다. 정지상으로는 monomeric $C_{18}$ 컬럼($\mu-{Bondapak}$)과 polymeric $C_{18}$ 컬럼(201TP)을 사용하여 상호 비교하였으며, 이동상으로는 메탄올-물과 아세토니트릴-물 혼합액을 사용하고, 대상물질로는 25종의 페놀류를 선택하였다. 엔탈피-엔트로피 상쇄현상을 조사하였을 때 nitrophenols의 머무름은 이동상에 관계없이 methylphenols와 chlorophenols의 머무름과는 달랐으며, 메탄올-물 이동상에서 methylphenols와 chlorophenols는 상쇄현상이 있기 때문에 그 머무름 메카니즘은 조성과 관계없이 일정하였고, 아세토니트릴-물에서는 머무름 메카니즘이 더욱 복잡함을 알았다. Monomeric $C_{18}$ 컬럼과 polymeric $C_{18}$ 컬럼에서의 페놀류의 머무름을 비교하였을 때, polymeric $C_{18}$ 컬럼에서 정지상과 시료의 소수성 상호작용이 더 큼을 알 수 있었다. 메탄올-물 및 아세토니트릴-물 계에서 이동상의 조성 및 컬럼 온도가 변화할 때 쉽게 계산할 수 있는 $\pi$와 ${\sigma}+E_s$ 파라미터를 이용하여 페놀류의 머무름을 예측할 수 있는 관계식을 구하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권6호
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• pp.671-677
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• 2015

A novel phase interpolator (PI) based linear model of multipath ring oscillator (MPRO) is described in this paper. By modeling each delay cell as an ideal summer followed by a single pole RC filter, the oscillation frequency is derived for a 4-stage differential MPRO. It is analytically proved that the oscillation frequency increases with the growth of the forwarding factor ${\alpha}$, which is also confirmed quantitatively through simulation. Based on the proposed model, it is shown that the power to frequency ratio keeps constant as the speed increases. Running at the same speed, a 4-stage MPRO can outperform the corresponding single-stage ring oscillator (SPRO) with 27% power saving, making MPRO with a large forwarding factor ${\alpha}$ an attractive option for lower power applications.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.124-125
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• 2001

The electro-magnetic vector equation(F=$qv{\times}B$ ; F：force, B：magnetic field, q：plus charge, v ：velocity of the charge) explains well about the rotations of electron and positron under the magnetic field[Ref.1], as in Fig.1(a). Because the electro-magnetic wave is also a motion of the alternating charge and magnetic field as in Fig.2, the force vector has all the time inwarding direction and then the wave has a rotating motion. The positron in the proton has constant charge and alternating one at the same time[Ref.2] and then the alternating charge makes the absorbing force with the alternating charge of the rotating wave ($\pi$-ray) around the nucleus[Ref.2]. (omitted)

• Journal of Power Electronics
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• 제8권2호
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• pp.131-140
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• 2008

This paper presents a new control approach of DSTATCOM (distribution static compensator) for compensation of reactive power, unbalanced loading and harmonic currents under unbalanced non-sinusoidal ac mains. The control of DSTATCOM is achieved using Adaline based current estimator based on LMS algorithm to maintain source currents real and undistorted. The dc bus voltage of voltage source converter (VSC) working as DSTATCOM is maintained at constant voltage using a proportional-integral (PI) controller. The DSTATCOM system alongwith proposed control scheme is modeled in MATLAB to simulate the behavior of the system. The practical implementation of the DSTATCOM is carried out using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. Simulated and implementation results are presented to demonstrate the effectiveness of the DSTATCOM with Adaline based control to meet the severe load perturbations with different types of loads (linear and non-linear) under distorted and unbalanced AC mains.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.670-674
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• 1992

This paper presents a velocity regulation scheme for a DC motor subjected to random torque and velocity measurement noises of white noise type as well as unknown constant load torque (bias). The scheme separately estimates an unknown bias in addition to state estimation by the bias-free Kalman Filter, and reflects the effect of the bias estimate to the armature input voltage such that velocity variations be regulated. It is shown via computer simulations that the performance of the present scheme is superior to that of the conventional analog PI regulator.

• Applied Biological Chemistry
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• 제38권2호
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• pp.163-167
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• 1995

살충성Buprofezine분자의 구조를 변형한 20종의 새로운 isothiourea유도체(S)를 합성하고 N-치환(Z)amino기의 변화에 따르는 6종의 해충에 대한 살충활성을 검토한 바, 배추 좀나방(Plutella Xylostella Linnaeus)에 대하여 현저하게 선택적인 살충성을 나타내었다. N-치환(Z) amino기의 치환기(Z)가 변화함에 따른 물리-화학적 파라미터와 배추 좀나방에 대한 살충활성값 (Obs. $pI_{50}$)과의 구조-활성 관계(SAR)식으로부터 살충활성에 미치는 물리-화학적 파라미터의 영향은 MR>${\pi}$>$L_1$의 순이었으며, 이들 파라미터의 적정값(optimal value)은 각각 $L_1=5.22{{\AA}}$, $MR=15.70(Cm^3/mol)$ 및 ${\pi}=1.60$이었다. 이 값을 만족하는 치환기(Z)로는 탄소 원자수가 3개로 구성된 iso-propyl 치환체(5)로써 가장 큰 살충성(Obs. $pI_{50}=3.00$)을 나타내었다.