• Journal of Power Electronics
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• v.9 no.1
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• pp.26-35
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• 2009

A high efficiency active clamp sepic-flyback converter is presented for fuel cell generation systems. The proposed converter is a superposition of a sepic converter mode and. flyback converter mode. The output voltages of the sepic converter mode and flyback converter mode can be regulated by the same PWM technique with constant frequency. By merging the sepic and flyback topologies, they can share the transformer, power MOSFET and active clamp circuit. The result has outstanding advantages over conventional active clamp DC-DC converters: high efficiency, high power density, and component utilization. Simulation results and experimental results are presented to verify the principles of operation for the proposed converter.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.495-509
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• 2013

In this study, we develop a one-dimensional (1-D), two-phase, transient-thermal DMFC model to investigate the effect of methanol concentration fluctuation that usually occurs in active-type direct methanol fuel cell (DMFC) systems. 1-D transient simulations are conducted and time-dependent behaviors of DMFCs are analyzed under various DMFC operating conditions such as anode/cathode stoichiometry, cell temperature, and cathode inlet humidification. The simulation results indicate that the effect of methanol concentration fluctuation on DMFC performance can be mitigated by proper control of anode/cathode stoichiometry, providing a guideline to optimize operating conditions of active DMFC systems.

• The Korean Journal of Zoology
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• v.16 no.2
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• pp.109-118
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• 1973

The morphological changes of the enterochromaffin cells in the gastrointestinal mucosae of Rana amurensis were observed during pre-hibernating, hibernating, post-hibernating and active period. The results of the observation are as follow: 1. The relative values of the enterochromaffin cell numbers in the pre-hibernating, hibernating and post-hibernating groups as compared with the active group are 1.50, 0.36 and 0.90, respectively. 2. In active and pre-hibernating groups, the enterochromaffin cells are large and middle-amount granulated cells and the sparse granulated cells increase significantly during hibernating and post-hibernating periods. 3. It is concluded that the morphological changes of enterochromaffin cells are due to lowered metabolic acitvities especially lowered endocrine activity during hibernation.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.939-942
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• 2016

One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (N_d) of the active layer on the J-V curve. When the active layer thickness was varied (for N_d = 8×10¹⁷ cm^-3) from 800 nm to 100 nm, the reverse saturation current density (J_o) changed from 3.56×10^-5 A/cm² to 9.62×10^-11 A/cm² and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (N_d = 4×10¹⁵ cm^-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (J_o = 9.62×10^-11 A/cm²) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.423-432
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• 2012

We design a control circuit that can switch input power between a rechargeable battery and a sensor communication device (mote) depending on the operating state of a solar cell as well as the active and sleep mode of a sensor MAC protocol. A mote that simply combines a solarcell and a rechargeable battery may die if there is not sunlight long. A battery is recharged if sunlight is sufficient and a device is in a sleep mode, and it supplies power if sunlight is low and the mote is in an active mode. A mote can switch its input power between solar cell and battery depending on the output level of a solar cell. During this switching, a mote may lose its state information due to the reset of a microprocessor by the transient power-off. A capacitor is used to cope with this phenomenon and also supplies power to a mote during a sleep mode. Experimental results show that the solar cell based mote operates in a very stable manner against the lack of sunlight long.

• YAKHAK HOEJI
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• v.34 no.5
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• pp.348-364
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• 1990

The activities of twenty-one flavonoids and their related compounds on the hypersensitivity reaction against various antigens were studied in vitro and in vivo. 1. Generally flavonoids inhibited significantly the homologous passive cutaneous anaphylaxis (PCA) induced by reaginic antibody as compared as anaphylaxis by compound 48/80-induced mast cell degranulation, and so more strongly active in the IgE-mediated anaphylaxis than non-IgE-mediated anaphylaxis. 2. Flavonids inhibited remarkably Arths reaction, hemolysin titer, delayed hypersensitivity, haemagglutinin titer, rosette forming cells and plague forming cells against sheep red blood cells, and so it exhibited that flavonoids inhibited type 2, 3 and 4 hypersensitivity. 3. Quercetin, kaempferol, hesperetin, disodium cromoglycate, malvin and baicalein were active dose-dependently in the all types of hypersensitivity. Fisetin, daidzein, morin, narigin, flavone, catechin, rutin, hesperidin, neophsperidin, apigenin and chrysin were significantly active in the various types of hypersensitivity, but apigenin, rutin and catechin were less active in the delayed hypersensitivity. Taxifolin was significantly active in PCA and histamine-induced anaphylaxis except other types of hypersensitivity. Rotenone and cyanin also inhibited all types of hypersensitivity, but they are toxic. 4. Based on these results from hypersensitivity, the following flavonoid structure-activity relationships became apparent. 1) Flavonoids with $C_{2-3}$ double bond in C-ring were more active than that of $C_{2-3}$ saturation. 2) Flavonoids with $C_4$ ketone group in C-ring were more active than abscence of them except catechin and malvin. 3) Flavonoids with benzene ring at positions 2 or 3 in C-ring exhibited same activities. 4) Flavonoids with opening of the C-ring does not abolish their activities. 5) The glycosylated flavonoids in position 3 or 7 was less active than their aglycone. 6) Flavonoids with the more hydroxy group in A and B-ring were more active. 7) Flavonoids with or without $C_3-OH$ did not change their activities.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.159-169
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• 2004

In this study, integration control of air-cell seat and semi-active suspension is proposed to minimize the road-tyre force which can cause uncomfortable feeling to rider. The proposed integration control with sliding perturbation observer is consisted of air-cell seat control which uses the force generated by air-cell and the sky-hook control. The air-cell seat itself has been modeled as a 1 degree of freedom spring-damper system. The actual characteristics of the air-cell have been analyzed through experiments. In this paper, we introduces a new robust motion control algorithm using partial state feedback for a nonlinear system with modelling uncertainties and external disturbances. The major contribution of this work is the development and design of robust observer for the state and the perturbation. The combination skyhook controller and air-cell controller using the observer improves control performance, because of the robust routine called Sliding Observer Design for Integration Control of Air-Cell Seat and Semi-active Suspension. The simulation results show a high accuracy and a good performance.

• Journal of Oriental Neuropsychiatry
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• v.20 no.3
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• pp.1-13
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• 2009

Objectives : The glial cell, located in between the blood vessel and nerve cell, takes charge of the cell support, nutrition supply, elimination of body waste, and cell action. GagamSohabhwangwon(GGSH), a chinese traditional medicinal prescription has been used orally for the treatment of seizures, infantile, convulsion, stroke and so forth. This paper examines the effect of the GagamSohabhwangwon(GGSH) essential oil on cell activity and anti oxidation. Methods : MTT assay methods were employed to measure the cell activity based on the amount of the GagamSohabhwangwon(GGSH) essential oil by using primarily cultivated glial cell. In addition, this paper measured a viability of the glial cell after a protein active retarder control to confirm the multiplication of the cell and examined the cell extinction by the active oxygen, an extinction shielding effect with different amount of the GagamSohabhwangwon(GGSH) essential oil to observe anti oxidation. Furthermore, this paper measured a viability of the cell and phosphorylation(phosphorylation) of the protein which affects the multiplication of the glial cell. Results : When controlling the amount of the GagamSohabhwangwon(GGSH), there was a multiplication effect of the primary glial cell, the multiplication of the cell was dependent on the density of the GagamSohabhwangwon. The multiplication power of the primary glial cell was suppressed by PKA inhibiter (H89). In compliance with the active oxygen the extinction of the primary glial cell was dependent on the density of the GagamSohabhwangwon, there was a shielding effect of the cell extinction when GagamSohabhwangwon(GGSH) was preprocessed. When inducing the multiplication of the primary glial cell, phosphorylation of the Akt, BDNF, CREB, ERK and ERM were increased. Conclusions: Based on the results, GagamSohabhwangwon essential oil will have the effect which activates the nervous system cell and protects the cell through anti oxidation.

• Journal of the Korea Society for Simulation
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• v.13 no.4
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• pp.1-16
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• 2004

The modelling and simulation of the activation process for the heart system is meaningful to understand special excitatory and conductive system in the heart and to study cardiac functions because the heart activation conducts through this system. This thesis proposes two dimensional cellular automaton(CA) model for the activation process of the myocardium and conducted simulation by means of discrete time and discrete event algorithm. In the model, cells are classified into anatomically similar characteristic parts of the heart and each of cells has a set of cells with preassigned properties. Each cell in this model has state variables to represent the state of the cell and has some state transition rules to change values of state variables executed by state transition function. The state transition rule is simple as follows. First, the myocardium cell at rest stay in passive state. Second, if any one of neighborhood cell in the myocardium cell is active state then the state is change from passive to active state. Third, if cell's state is an active then automatically go to the refractory state after activation phase. Four, if cell's state is refractory then automatically go to the passive state after refractory phase. These state transition is processed repeatedly in all cells through the termination of simulation.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.305-308
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• 2007

The field of dye-sensitized solar cell (DSC) is being researched actively at present. Because DSC has several advantages to pass the limits of Si solar cells such as a low manufacturing expense, a simple manufacturing process and its transparency. A lot of researches are underway about materials and processes in the field of dye-sensitized solar cell but its structure has been fixed up as the sandwich structure that both edges are used as positive and negative terminals. But the structure as of present is a factor of decreasing efficiency because the more electrons are recombined the further distance from terminal, considering about the characteristic of dye-sensitized solar cell that electrons generated inside cell are moved by diffusion. In this study, we made experiment on expanding the terminal to shorten internal moving distance of electron and compared the results according to the variation of active area to find out the effect of this trial. As a result, we achieved about 15.5% improvement of maximum power and 0.5% improvement of efficiency from terminal-expanded dye-sensitized solar cell of $2cm^{2}$ active area and concluded that the increasing rate of efficiency is raised as the active area becomes wider.