• 한국통신학회논문지
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• 제31권11A호
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• pp.1092-1100
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• 2006

본 논문에서는 4개의 송신 안테나에서 full rate를 달성할 수 있는 준직교 QOSTF-OFDM(quasi-orthogonal space-time-frequency block coded orthogonal frequency division multiplexing)기법을 제안한다. 제안된 방식은 full rate를 달성할 수 있지만 full diversity를 달성할 수 없기 때문에 수신기에서 diversity손실을 보상하기 위해 DAC-ZF(diversity advantage collection with zero forcing)수신 기법을 사용한다. 동일한 주파수 효율을 가진다는 가정하에서 제안된 방식은 full rate을 달성할 수 없는 다른 선형 직교 시공간 기법과 비교할 때 full rate를 달성할 수 있기 때문에 저 레벨(low level) 변조 기법을 적용함으로써 변조 이득(modulation advantage)을 얻을 수 있다. 모의 실험 결과 제안된 방식은 변조 이득과 collected 다이버시티 이득으로 인해 다른 직교 방식과 비교하여 더 높 BER성능을 얻을 수 있다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.469-471
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• 1999

In this paper, the method of Space-Vector Pulse Width Modulation(SVPWM) with Fuzzy Logic Regulator(FLR) is proposed. In a conventional SVPWM, the procedures of phase transformation and choosing PWM patterns are complex. So, it should be implemented with high performance processor like Digital Signal Processor(DSP). In order to reduce a calculation burden, a proposed system adopts FLR. Using a linguistic contro strategy based on expert knowledge, FLR relieves the processor from a heavy computations. In simulations, the proposed system is validated.

• 한국발생생물학회지:발생과생식
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• 제16권4호
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• pp.265-270
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• 2012

Ethanol actions in the amygdala formation may underlie in part the reinforcing effects of ethanol consumption. Previously a physiological phenomenon in the basolateral amygdala (BLA) that is dependent on neuronal network activity, compound postsynaptic potentials (cPSPs) were characterized. Effects of acute ethanol application on the frequency of cPSPs were subsequently investigated. Whole cell patch clamp recordings were performed from identified projection neurons in a rat brain slice preparation containing the amygdala formation. Acute ethanol exposure had complex effects on cPSP frequency, with both increases and decreases dependent on concentration, duration of exposure and age of the animal. Ethanol produces complex biphasic effects on synaptically-driven network activity in the BLA. These findings may relate to subjective effects of ethanol on arousal and anxiolysis in humans.

• Journal of Nutrition and Health
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• 제27권9호
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• pp.892-900
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• 1994

A variety of important roles for branched-chain amino acids in metabolic regulation has been suggested. Branched-chain $\alpha$-keto acid dehydrogenase(BCKAD) complex is a rate limiting enzyme in branched-chain amino acid metabolism. The purpose of this study was to examine the effects of exercise on the activity and activity state of branched-chain $\alpha$-keto acid dehydrogenase in rat hert and liver thssues. Forty-eight Sprague-Dawley rats were assigned into three experimental groups : sedentary control, exercised, or exercised-rested. Submaximal exercise(running) for two hours significantly increased basal activity without a change in total activity in both tissues, with a concomitiant increase in activity state of the enzyme complex. At 10 min post-exercise, heart enzyme activity significantly decreased, though not to the control level, while liver enzyme activity remained unchanged. These data suggested that the exercise-induced increase in branched-chain $\alpha$-keto acid decarboxylation in rat tissues may not be the result of enzyme synthesis, but rather is due to increased activity of the BCKAD.

• Journal of Power Electronics
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• 제9권4호
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• pp.567-574
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• 2009

A linear transfer function for the output current control of frequency-controlled resonant inverters is proposed in this paper. The circuit of resonant inverters can be transformed into two coupled circuits through the complex phasor transform. The circuits consist of cross-coupled power sources and passive elements. The circuits are used to induce the state space equation, which is transformed into the $4^{th}$ order cross-coupled transfer function. The $4^{th}$ order cross-coupled transfer function is modeled into a $2^{nd}$ order linear transfer function based on a behavior analysis of the pole and zero locations that facilitate a simple and intuitive linear transfer function. The feasibility and validity of the proposed linear transfer function were verified by simulation and experiment.

• 대한전기학회논문지:전력기술부문A
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• 제48권11호
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• pp.1464-1471
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• 1999

This paper introduces complex-valued competitive learning neural network for spatio-temporal pattern recognition. There have been quite a few neural networks for spatio-temporal pattern recognition. Among them, recurrent neural network, TDNN, and avalanche model are acknowledged as standard neural network paradigms for spatio-temporal pattern recognition. Recurrent neural network has complicated learning rules and does not guarantee convergence to global minima. TDNN requires too many neurons, and can not be regarded to deal with spatio-temporal pattern basically. Grossberg's avalanche model is not able to distinguish long patterns, and has to be indicated which layer is to be used in learning. In order to remedy drawbacks of the above networks, unsupervised competitive learning using complex umber is proposed. Suggested neural network also features simultaneous recognition, time-shift invariant recognition, stable categorizing, and learning rate modulation. The network is evaluated by computer simulation with randomly generated patterns.

• BMB Reports
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• 제56권6호
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• pp.335-340
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• 2023

During normal physiological and abnormal pathophysiological conditions, all cells release membrane vesicles, termed extracellular vesicles (EVs). Growing evidence has revealed that EVs act as important messengers in intercellular communication. EVs play emerging roles in cellular responses and the modulation of immune responses during virus infection. EVs contribute to triggering antiviral responses to restrict virus infection and replication. Conversely, the role of EVs in the facilitation of virus spread and pathogenesis has been widely documented. Depending on the cell of origin, EVs carry effector functions from one cell to the other by horizontal transfer of their bioactive cargoes, including DNA, RNA, proteins, lipids, and metabolites. The diverse constituents of EVs can reflect the altered states of cells or tissues during virus infection, thereby offering a diagnostic readout. The exchanges of cellular and/or viral components by EVs can inform the therapeutic potential of EVs for infectious diseases. This review discusses recent advances of EVs to explore the complex roles of EVs during virus infection and their therapeutic potential, focusing on HIV-1.

• 한국자기공명학회논문지
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• 제11권2호
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• pp.95-109
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• 2007

Vanadium-incorporated aluminophosphate microporous molecular sieve VH-SAPO-42 has been studied by electron spin resonance(ESR) and electron spin-echo modulation (ESEM) spectroscopies to determine the vanadium location and interaction with various adsorbate molecules. The results are interpreted in terms of V(IV) ion location and coordination geometry. Assynthesized VH-SAPO-42 contains only vanadyl species with distorted octahedral or trigonal bipyramidal coordination. Vanadium incorporated into H-SAPO-42 occupied extra-framework site. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. Species A is identified as a $VO(H_2O)_2^{2+}$ complex coordinated to three framework oxygen atoms bonded to aluminum. When hydrated VH-SAPO-42 is dehydrated at elevated temperature by calcination, species A loses its water ligand and transforms to $VO^{2+}$ ions coordinated to three framework oxygens (species B). Species B reduces its intensities significantly after treatment with $O_2$ at high temperature, thus suggesting oxidation of $V^{4+}$ to $V^{5+}$. When dehydrated VH-SAPO-42 makes contact with $D_2O$ at room temperature, the ESR signal of species A is regained. The species is assumed as a $VO(O_f)_3(D_2O)_2$ by considering three framework oxygens. Adsorption of deuterated methanol on dehydrated VH-SAPO-42 results in another new vanadium species D, which is identified as a $VO(CD_3OH)_2$ complex. When deuterated ethylene is adsorbed on dehydrated VH-SAPO-42, another new vanadium species E identified as a $VO(C_2D_4)^{2+}$, is observed. Possible coordination geometries of these various complexes are discussed.

• 대한전자공학회논문지TC
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• 제37권1호
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• pp.1-11
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• 2000

본 논문에서는 다중 반송파 부호 분할 다원 접속 (multi-carrier-code division multiple access; MC-CDMA) 시스템 내의 고출력 증폭기에 의해 발생하는 비선형 왜곡의 보상을 위한 전치왜곡기를 제안한다. 제안된 방법은 contraction mapping 정리와 이에 따른 고정점 반복에 기반하고 있다. 우리가 이미 다른 논문에서 제안하였던 고정점 반복 기반의 전치왜곡기가 복소수 변조 신호 자체에 적용되는 것에 반해, 여기서 제안하는 전치왜곡기는 변조 신호의 진폭에 고정점 반복을 적용하여 실수 연산을 수행하므로써 계산량을 감소시킨다. 송신기에서 traveling wave tube amplifier를 고출력 증폭기로 사용하고, BPSK 변조와 64개의 부반송파를 이용하는 동기식 MC-CDMA 기저대역 시스템에 대한 컴퓨터 시뮬레이션 결과, 제안된 전치왜곡기를 사용하는 경우 그렇지 않은 경우에 비해 비트오율 및 total degradation의 측면에서 월등한 성능 향상이 가능함을 알 수 있었다. 또한, 작은 output back-off 레벨에 대해 제안된 전치왜곡기는 복소수 연산을 수행하는 기존의 공점점 반복 기반의 전치왜곡기보다 우수한 성능을 보임을 역시 확인하였다.

• 한국광학회지
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• 제17권2호
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• pp.191-197
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• 2006

두 개의 DFB 영역과 위상조정 영역으로 구성된 다중 영역 복소 결합 DFB 레이저에서 방출되는 두 모드의 비팅에 의해서 발생하는 Self-Pulsation(SP) 동작 특성을 전산 모의 하였다. SP 주파수는 두 DFB 영역에서 발진하는 모드의 파장 차이에 의해 결정되며, 각각의 DFB 영역의 발진 모드의 파장은 회절격자 주기의 변화에 의해 달라진다. 두 DFB 영역의 회절격자의 주기 차이를 변화시킴으로써 다중 영역 DFB 레이저에서 밭생하는 SP 주파수를 매우 낮은 주파수에서 THz 영역까지 변화시킬 수 있었다. 또한 발진 모드가 다른 DFB 영역의 금지대역에 놓이지 않는 경우 발진되는 모드는 다른 DFB 영역으로 큰 반사 없이 진행하여 두 모드들 사이의 상호작용이 크게 발생하여 index-coupled 회절격자를 가지는 다중 영역 DFB 레이저와는 달리 변조 지수가 매우 큰 출력을 얻을 수 있었다.