• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.29-30
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• 2013

Steel corrosion is the most serious problem in RC structures. Even though patch repair method is normally applied in repair system, the effectiveness is not enough. Cathodic protection in active repair method to deteriorated RC structures. FEM model was developed to simulate the optimized cathodic protection condition. Iro oxidation, hydrogen evolution and oxygen reduction were considered to expect current distribution. Moisture content in concrete which can affect the electrolyte conductivity was used as initial condition.

• Journal of Ginseng Research
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• v.20 no.2
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• pp.173-178
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• 1996

Aerobic cells are normally protected from the damage of free radicals by antioxidative on , zymes such as superoxide dismutase (SOD), catalase, glutathione (GSH) peroxidase, GSH S- transferase and GSH reductase which scavenge free radicals as well as nonenzymatic antioxidants such as ceruloplasmin, albumin and nonprotein-SH including GSH. The effects of each component (ginsenoside $Rb_1$, $Rb_2$, Rc, Rd, Re, $Rb_1$, Rf, $Rh_1$ and $Rh_2$) of red ginseng on the antioxidative enzyme activities were investigated in the liver in order to screen antioxidative components of red ginseng. Ginsenoside $Rb_1$ and Rc showed a tendency to increase GSH peroxidase activity, while ginsenoside Rc significantly decreased Cu,Zn-SOD activity. Especially, ginsenoside $Rh_2$ significantly increased catalase activity. These results suggest that ginsenoside $Rh_2$ is an important active component among total saponins of red ginseng.

• Archives of Pharmacal Research
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• v.26 no.1
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• pp.28-33
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• 2003

Ginsenosides, major active ingredients of Panax ginseng, are known to regulate excitatory ligand-gated ion channel activity such as nicotinic acetylcholine and NMDA receptor channel activity. However, it is not known whether ginsenosides affect inhibitory ligand-gated ion channel activity. We investigated the effect of ginsenosides on human recombinant $GABA_A$ receptor (${\alpha}_1{\beta}_1{\gamma}_{2s}$) channel activity expressed in Xenopus oocytes using a two-electrode voltage-clamp technique. Among the eight individual ginsenosides examined, namely, $Rb_1$, $Rb_2$, Rc, Rd, Re, Rf, $Rg_1$ and $Rg_2$, we found that Rc most potently enhanced the GABA-induced inward peak current ($I_{GABA}$). Ginsenoside Rc alone induced an inward membrane current in certain batches of oocytes expressing the $GABA_A$ receptor. The effect of ginsenoside Rc on $I_{GABA}$ was both dose-dependent and reversible. The half-stimulatory concentration ($EC_{50}$) of ginsenoside Rc was 53.2$\pm$12.3 $\mu$M. Both bicuculline, a $GABA_A$ receptor antagonist, and picrotoxin, a $GABA_A$ channel blocker, blocked the stimulatory effect of ginsenoside Rc on $I_{GABA}$. Niflumic acid (NFA) and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), both $CI^{-1}$ channel blockers, attenuated the effect of ginsenoside Rc on I$I_{GABA}$. This study suggests that ginsenosides regulated $GABA_A$ receptor expressed in Xenopus oocytes and implies that this regulation might be one of the pharmacological actions of Panax ginseng.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.29-36
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• 2023

Reinforcement learning (RL) is widely applied to various engineering fields. Especially, RL has shown successful performance for control problems, such as vehicles, robotics, and active structural control system. However, little research on application of RL to optimal structural design has conducted to date. In this study, the possibility of application of RL to structural design of reinforced concrete (RC) beam was investigated. The example of RC beam structural design problem introduced in previous study was used for comparative study. Deep q-network (DQN) is a famous RL algorithm presenting good performance in the discrete action space and thus it was used in this study. The action of DQN agent is required to represent design variables of RC beam. However, the number of design variables of RC beam is too many to represent by the action of conventional DQN. To solve this problem, multi-agent DQN was used in this study. For more effective reinforcement learning process, DDQN (Double Q-Learning) that is an advanced version of a conventional DQN was employed. The multi-agent of DDQN was trained for optimal structural design of RC beam to satisfy American Concrete Institute (318) without any hand-labeled dataset. Five agents of DDQN provides actions for beam with, beam depth, main rebar size, number of main rebar, and shear stirrup size, respectively. Five agents of DDQN were trained for 10,000 episodes and the performance of the multi-agent of DDQN was evaluated with 100 test design cases. This study shows that the multi-agent DDQN algorithm can provide successfully structural design results of RC beam.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.713-717
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• 2001

This paper focuses on a network model for GCTs which can be used to investigate high power circuits with or without using RC-snubbers. The series connection of GCTs is commonly applied in the high power inverter field. Here expensive and space-consuming snubbers are applied, to overcome the problem of an asymmetric distribution of the blocking voltage among the single GCTs. As an alternative to large snubbers, a new active gate drive concept is proposed and investigated by simulation.

• Journal of Industrial Technology
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• v.11
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• pp.43-53
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• 1991

Two kinds of simple active oscillators are proposed and analyzed assuming that operational amplifier has two-poles frequency characteristics. The first circuit is composed of one operational amplifier, one resistor and one grounded capacitor. The second oscillator is realized with one operational amplifier and three resitors. Proposed oscillators have the low sensitivity of the oscillation frequency for little variations of the passive element values. By the experimental results obtained with Op-Amp. ${\mu}A741$, the simple oscillators can be useful for the frequency range $1.25 KHz{\leq}f_{01}{\leq}40KHz$ for the active-RC type or $45.45 KHz{\leq}f_{02}{\leq}400KHz$ for the active-R oscillator, and it is shown to transform the active-R oscillator circuit into the voltage controlled type. Therefore, two kinds of oscillator circuit are attractive for the IC realization, because they have one operational amplifier, one resistor and one grounded capacitor, or three resistors.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1093-1104
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• 2015

A standard repetitive controller (RC) is theoretically able to replace a bank of resonant controllers in harmonic signals tracking applications. However, the traditional RC has some drawbacks such as a poor dynamic response and a complex structure to compensate grid frequency deviations for an effective unified power quality conditioner (UPQC) control scheme. In order to solve these problems, an improved RC with an outstanding dynamic response and a simplified grid frequency adaptive scheme is proposed for UPQC control systems in this paper. The control strategy developed for the UPQC has delay time, i.e., one-sixth of a fundamental period (T_p/6), repetitive controllers. As a result, the UPQC system can provide a fast dynamic response along with good compensation performance under both nonlinear and unbalanced loads. Furthermore, to guarantee the excellent performance of the UPQC under grid frequency deviations, a grid frequency adaptive scheme was developed for the RC using a simple first order Padé's approximation. When compared with other approaches, the proposed control method is simpler in structure and requires little computing time. Moreover, the entire control strategy can be easily implemented with a low-cost DSP. The effectiveness of the proposed control method is verified through various experimental tests.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.80.3-80
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• 2002

$\textbullet$ Janchitrapongvej Kanok(KMITL), $\textbullet$ Tangtisanon Prakit( KMITL), $\textbullet$ Janin Chainarong(KMITL), $\textbullet$ Panyanouvong Nouanchanh(KMITL), $\textbullet$ Saetia Sorapong(KMITL)

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.202-215
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• 2013

This paper proposes a SEPIC-input, self-driven, active clamp ZVS converter, where an auxiliary winding and a RC delay circuit are employed to drive the active clamp switch and to achieve asymmetrical duty control without any other extra circuits. Based on the fixed dead time and the resonance between capacitors and inductors, both the main switch and the auxiliary switch can rule the ZVS operation. Detailed operation modes are presented to illustrate the self-driven and ZVS principles. Furthermore, an accurate state-space model and the transfer functions of the proposed converter have been presented and analyzed in order to optimize dynamic performance. The model provides efficient prediction of converter operations. Experimental results, based on a prototype with 80V input and 15V/20A output, are discussed to verify the transient and steady performance of the proposed converter.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.367-373
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• 2014

In this study, we investigated the anticancer activity of methyl gallate (MG), which is the major biologically active component of Galla Rhois, in RC-58T/h/SA#4 human prostate cancer cells. MG inhibited cell proliferation in a dose-dependent manner. Cell death induced by MG increased the population of cells in sub-G1 phase, formation of apoptotic bodies, nuclear condensation, and DNA fragmentation. Apoptosis induced by MG was associated with activation of initiator caspases-8 and -9 as well as effector caspase-3. Endocrine disruptors such as dioxin and bisphenol A increased growth of RC-58T/h/SA#4 cells in charcoal-treated FBS (cFBS) medium. Cell proliferation was highest upon treatment with 1 nM and $0.1{\mu}M$ dioxin and bisphenol A, respectively. MG also dose-dependently inhibited cell proliferation in RC-58T/h/SA#4 cells treated with endocrine disruptors. These results indicate that MG exerts anticancer effects on RC-58T/h/SA#4 primary human prostate cancer cells.