• Earthquakes and Structures
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• 제9권6호
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• pp.1133-1152
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• 2015

A frequency-domain method is developed for evaluating the earthquake input energy to two building structures connected by viscous dampers. It is shown that the earthquake input energies to respective building structures and viscous connecting dampers can be defined as works done by the boundary forces between the subsystems on their corresponding displacements. It is demonstrated that the proposed energy transfer function is very useful for clear understanding of dependence of energy consumption ratios in respective buildings and connecting viscous dampers on their properties. It can be shown that the area of the energy transfer function for the total system is constant regardless of natural period and damping ratio because the constant Fourier amplitude of the input acceleration, relating directly the area of the energy transfer function to the input energy, indicates the Dirac delta function and only an initial velocity (kinetic energy) is given in this case. Owing to the constant area property of the energy transfer functions, the total input energy to the overall system including both buildings and connecting viscous dampers is approximately constant regardless of the quantity of connecting viscous dampers. This property leads to an advantageous feature that, if the energy consumption in the connecting viscous dampers increases, the input energies to the buildings can be reduced drastically. For the worst case analysis, critical excitation problems with respect to the impulse interval for double impulse (simplification of pulse-type impulsive ground motion) and multiple impulses (simplification of long-duration ground motion) are considered and their solutions are provided.

• Journal of Biosystems Engineering
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• 제14권4호
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• pp.229-241
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• 1989

The purposes of this study were to develop an electronic-hydraulic draft control system for tractor implements, to investigate the control performance of the system and the possibility of adaptation to the conventional tractor. Experiments were carried out to investigate the responses of the system to the step and sinusoidal inputs in draft control. The effects of control mode, hydraulic flow rate, reference deadband, and proportional constant on control performance of the system were investigated. Moreover, the effects of filtering signals from draft sensor were also investigated. The following conclusions were derived from the study; 1. In draft control, there were hunting problems in controlling the implement without filtering the draft signals. Filtering was performed by a control program of electronic controller and the control performance and stability of the system were improved significantly. 2. For the draft control system operated on on-off control mode, draft was controlled within ${\pm}27-{\pm}55kg_f$ to the reference draft when the hydraulic flow rates were 5-15 l/min. For the draft control system operated on PWM control, draft was controlled within ${\pm}27kg_f$ to the reference draft regardless of hydraulic flow rates. 3. In the frequency responses of the draft control system, control performance on PWM control mode was not better than on on-off control mode because of characteristics of hydraulic valve and drafe sensor. As the hydraulic flow rates increased for the system operated on on-off control mode, the corner frequency of amplitude attenuation increased, but the corner frequency of phase-angle change remained nearly the same. But, the system was unstable beyond the frequency of 3.1 rad/s. 4. The electronic-hydraulic hitch control system developed in this study showed superior control performance, stability and convenience compared to conventional mechanical-hydraulic hitch control system. It is considered to be a superior replacement for the conventional mechanical-hydraulic hitch control system.

• 전기학회논문지
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• 제56권4호
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• pp.705-715
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• 2007

Recently, the interest on power quality has been hot issue because the equipments cause voltage disturbance and have become more sensitive to the voltage disturbance. Additionally, the reseach on power electronic equipments applying to the high power has been increased. This paper deals with Line-Interactive Dynamic Voltage Restorer(LIDVR) system using 7-Level H-Bridge inverter, which is one of the solutions to compensate the voltage disturbance and to increase the power of equipments. The LIDVR has the following advantages comparing to the DVR with the series injection transformer. It has the power factor near to unity under the condition of normal source voltage, can compensate the harmonic current of the load and the instant interruption, and has the fast response. First, the construction, the operation mode and algebraic modeling of LIDVR are reviewed. And then the voltage control algorithm is proposed to get the sinusoidal load voltage with constant amplitude. Finally, simulation and experiment results verify the proposed LIDVR system.

• 대한방사선기술학회지:방사선기술과학
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• 제16권2호
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• pp.19-26
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• 1993

Magnetic Resonance Image represents three-dimensional diagnostic imaging technique using both nuclear magnetic resonance phenomenon and computer. Compared with computed tomography (CT), MRI have advantages harmless to patient's body, three-dimensional image with high resolution and disadvantages long data acquisition time because of long T1 relaxation time, relatively low signal to noise ratio, high cost of setting, also. As physiologic motion of tissue results in motion ghost in MRI, high 2.0Tesla make improve low signal to noise ratio. This study have aim to improve image quality with controling motion ghost of tissue. Supposing a moving pixel in constant frequency, one pixel make two ghosts which are same size and different anti-phase. So, this study will show adjust parameter on locational control of motion ghost. Author made moving phantom replaced by respiratory movement of human, researched change of motion frequency, FOV by location shift, and them decided optimal FOV (field of view). The results are as follows: 1. The frequency content of the motion determines how far the image always appear in phase-encoding direction, the morphology of the ghost image is characteristic of the direction of the motion and its amplitude. 2. Double FOV of fixed signal object for locational control of motion ghost is recommended. Decreasement of spatial resolution by increasing FOV can compensate on increasing of matrix in spite of scan time increasement.

• The Korean Journal of Physiology and Pharmacology
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• 제6권2호
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• pp.71-80
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• 2002

Previous studies have suggested that brain stem noradrenergic inputs differentially modulate neurons in the paraventricular nucleus (PVN). Here, we compared the effects of norepinephrine (NE) on spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs) in identified PVN neurons using slice patch technique. In 17 of 18 type I neurons, NE $(30{\sim}100{\mu}M)$ reversibly decreased sIPSC frequency to $41{\pm}7%$ of the baseline value $(4.4{\pm}0.8\;Hz,\;p<0.001).$ This effect was blocked by yohimbine $(2{\sim}20{\mu}M),$ an ${\alpha}_2-adrenoceptor$ antagonist and mimicked by clonidine $(50{\mu}M),$ an ${\alpha}_2-adrenoceptor$ agonist. In contrast, NE increased sIPSC frequency to $248{\pm}32%$ of the control $(3.06{\pm}0.37\;Hz,\;p<0.001)$ in 31 of 54 type II neurons, but decreased the frequency to $41{\pm}7$ of the control $(5.5{\pm}1.3\;Hz)$ in the rest of type II neurons (p<0.001). In both types of PVN neurons, NE did not affect the mean amplitude and decay time constant of sIPSCs. In addition, membrane input resistance and amplitude of sIPSC of type I neurons were larger than those of type II neurons tested (1209 vs. 736 $M{\Omega},$ p<0.001; 110 vs. 81 pS, p<0.001). The results suggest that noradrenergic modulation of inhibitory synaptic transmission in the PVN decreases the neuronal excitability in most type I neurons via ${\alpha}_2-adrenoceptor,$ however, either increases in about 60% or decreases in 40% of type II neurons.

• 수산해양기술연구
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• 제16권1호
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• pp.43-47
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• 1980

The author designed and tested the high sensitive three-phase power factor meter and relay circuit, and dealt with the circuit to detect the phase of the current and the voltage. An operational amplifier comparator circuit and two single-phase transformers are used to control and detect the phase angle between the current and the voltage. The results obtained are as follows: 1. Converting the sine wave input current into the constant amplitude rectangular wave form by using a transistor chopper circuit, the power factor can be measured precisely over the load current of 0.08 A. 2. Using the moving coil type current meter, the power factor meter can be read in uniform . scale all over the range. 3. Using the three-phase power factor meter, the power factor relay which works at any power factor can be made.

• 한국통신학회논문지
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• 제12권5호
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• pp.527-534
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• 1987

진동에 관한 비선형 1계연립미분방정식을 아나로그 시뮬레이션으로 2상전압제어발진을 시켜 유용성을 확인하였다. 2상신호를 각각 제곱하여 합성하는 부분과 곱셈부분의 실제회로 구성시 복잡하고 가격이 높아지므로 정류 회로와 스위칭회로로 대치하여 회로의 단순화와 가격 저렴화를 이루었다. 본 논문에서 제시된 회로는 제어 압력전압에 주파수가 정확한 비례관계를 가졌고, 응답 속도가 비교적 빠르고 또한 위상오차가 매우 적었으며 주파수비가 10:1 이상에서도 저왜율과 정진폭으로 동작하였다.

• 대한약리학회지
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• 제20권2호
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• pp.35-47
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• 1984

실험적으로 L:D, 12:12또는 D:D, 12:12에 적응시킨 흰쥐의 간뇌에서 beta-endorphin함량의 일중변동과 이에 대한 수종 중추성 약물의 효과를 검토하고 beta-endorphin함량의 생리 및 약리학적 의의를 추구코저 $^3H-morphine$ binding을 측정하여 다음과 같은 성적을 얻었다. 1) L:D, 12:12 cycle에 적응시킨 대조군에서 뇌내 beta-endorphin함량은 06 : 00시 에 최고에 달하고 18 : 00시에 최저인 대단히 유의한 일중변동을 일으켰고 24시간 평균 beta-endorphin함량은 $46.7{\pm}3.6$ fmole/mg protein 이었다. 2) D:D, 12:12에 적응시친 표본에서 beta-endorphin 함량은 대조군에서와는 달리 14 : 00시에 최고에 이르고 02 : 00시에 최저에 이르는 일중변동을 보였으며 24시간 평균 beta-endorphin함량도 대조군에 비하여 현저히 감소되었다. 3) 뇌내 beta-endorphin함량 일중별동은 reserpine. pargyline, imipramine, amphetamine. 또는 chlorpromazine처리로써 변동되었다. 4) 대조군에서 $^3H-morphine$ binding은 22 : 00시에 최고에 달하는 일중변동을 보였으며, 지속적인 암적응군에서의 binding은 02 : 00최고, 그리고 14 : 00시에 최하에 이르는 일중변동을 보였다. 5) 대조군과 지속적인 암적응군에서 함량과 maximum $^3H-morphine$ binding간에는 유의한 역상관관계가 있었다. 이상의 실험성적으로 흰쥐 뇌내 beta-endorphin함량과 수용체는 유의란 일중변동을 일으키고 opiate receptor binding의 일중변동은 beta-·endorphin함량변동에 따른 receptor regulation에 의함을 시사하며 또한 지속적인 암적응을 포함하여 수종 중추에 작용하는 약물들이 endorphin함량 일중변동을 변동시킬 수 있음을 보여 준다.

• 한국전문물리치료학회지
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• 제8권4호
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• pp.81-89
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• 2001

전시냅스 억제(presynaptic inhibition)와 동시냅스 억제(homosynaptic depression)는 보행 시에 분절반사(segmental reflex)를 조절하는 두 가지 독립적인 기전이다. 근방추 피드백(feedback)은 전시냅스 억제(inhibition)를 통해 보행 시 원심성 근육 수축기에서 적절이 조절될 수 있다. 이러한 전시냅스 억제 작용은 H-reflex의 강도로 나타내질 수 있는데, 원심성 근육 수축기 동안 H-reflex의 강도가 약해지는 것으로 보아 전시냅스 억제 작용은 증가되는 것으로 보여진다. 근방추 구심성 피드백(feedback) 역시 동시냅스 억제를 통해서 조절될 수 있다. 따라서 전시냅스와 동시냅스 억제는 보행 시작 중에 반사의 기전을 조절하는 중요한 역할을 한다. 반사의 조절 기전은 알파(alpha) 운동 신경원의 흥분도와 더불어 상위 척수의 기전들을 통해서 영향받고 조절된다. 경직성 마비 환자들은 초기의 입각기, 혹은 유각기 중에 손상된 비정상 비복근 H-reflex 조절기전을 보여준다. 이러한 비정상적인 조절기전은 발바닥의 말초신경을 자극함으로써 부분적으로 회복될 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2249-2251
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• 1997

Total 144 quadrupole magnets are installed in PLS. The magnets are connected in series with groups of two or 24. Each group is powered by a high-precision constant-current DC power supply. For the purpose of the beam based alignment of beam position monitors in the PLS, it is necessary to adjust the current of each quadrupole independently. To achieve this, a high current shunt regulator is designed. It can shunt a maximum 50 A of the quadrupole magnet current. The shunt regulator is programmable and the current amplitude can be varied linearly with a 12-bit resolution. Power transistors are used in the current shunt regulator. The operation of transistors is in linear region. The RS232C protocol is used for remote control and status report of the shunt regulator to the main control centre of the PLS. Preliminary result indicates that the calibration accuracy of the beam position monitor can be achievable in less than $10{\mu}m$.