• 한국자동차공학회논문집
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• 제20권5호
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• pp.145-151
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• 2012

New design of catalytic converter is proposed by optimization of DFSS (Design For Six Sigma) and DOE (Design Of Experiment) method which is based on taguchi matrix. As a result of the optimization of design of catalytic converter, this paper classifies Exhaust-downpipe shapes with 3 parameters to increase flow velocity uniformity of front catalytic substrate face from CFD results. after finishing with L9 Taguchi test matrix, it can be found the main effect of each design parameter of concept model, and optimal design level. in conclusion, it can be increase flow uniformity from 0.60 upto 0.80 with optimal diffuser shape for Turbo-charger.

• 한국환경과학회지
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• 제29권9호
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• pp.935-938
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• 2020

This study investigated the oviposition characteristics of Protaetia brevitarsis seulensis after emergence as adults from the larva collected from three regions in Gangwon-do, Chungcheongnam-do, and Jeju-do. The laying egg method was identified with zone breeding, and the average and cumulative number of eggs laid were measured once a week for seven weeks. The average number of eggs laid peaked until 4 weeks, and subsequently decreased. The source areas with respect to average number and cumulative number of eggs laid were in the order of Jeju > Chungnam > Gangwon. In conclusion, this result suggests a method for continuously improving management and economic feasibility of insect farming by securing genetic diversity, and raising the most productive breeds to select individuals form regions associated with high numbers of laid eggs.

• 응용통계연구
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• 제25권5호
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• pp.865-875
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• 2012

In this study, we identify the variables that affect the number of crime and spatial correlation in the Seoul metropolitan area, in addition, we measure the relative risk on the incidence of crime by a Poisson regression model. We suggest a statistical methodology to make a risk map for crime based on relative risk instead of the total event of crime by region using the Geographic Information System. To demonstrate the use and advantages of this methodology, this study presents an analyses of the total crime count in 25 wards in the Seoul metropolitan area.

• Journal of Plant Biotechnology
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• 제7권3호
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• pp.169-174
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• 2005

The optimal culture conditions were studied for plant regeneration from mesophyll protoplasts of Solanum sisymbriifolium. Axenic seedlings of S. sisymbriifolium were used as a explant for protoplast culture. Many viable protoplasts were isolated by incubating leaf slices in an enzyme solution containing 0.25% Meicerase and 0.05% Macerozyme for 16 hr at $25^{\circ}C$ without shaking. Protoplast density of $5.0{\times}10^4\;ml^{-1}$ in Kao medium containing 5.0 mg/L NAA, 1.0 mg/L 2,4-D and 1.0 mg/L BA was optimal for colony formation. Most colonies were formed when protoplasts were cultured at $25^{\circ}C$ after initial culture at $30^{\circ}C$ for one week. On the MS agar medium with 1.0 mg/L zeatin, 38.4% of protoplast-derived calli differentiated shoots. These shoots rooted on 1/2MS medium with 5.0 g/L sucrose and 2.5 g/L gellan gum, and developed into whole plants.

• 한국세라믹학회지
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• 제41권7호
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• pp.497-502
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• 2004

A hybrid coextrusion and lamination process has been developed to fabricate macrochanneled bioceramic scaffolds. This process was mainly composed of three steps (i.e., coextrusion of thermoplastic compound, lamination, and thermal treatment), forming unique pore channels in dense bioceramic body. Pore channels were formed by removing carbon black material, while calcium phosphate or Tetragonal Zirconia Polycrystals (TZP) with a calcium phosphate coating layer were used as dense body. Two kinds of pore structures were fabricated; that is, the pore channels were formed in uni- or three-directional array. Such macrochanneled bioceramic scaffolds exhibited the precisely controlled pore structure (pore size, porosity, and interconnection), offering excellent mechanical properties and cellular responses.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.82-86
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• 2010

Quinine (QN) is a weak anion-exchange type chiral selector and QN-based silica stationary phases have been widely used for enantioseparation of acidic chiral analytes in HPLC and recently in CEC. In this work we report enantioseparation of non-acidic chiral analytes on a quinine carbamate-immobilized zirconia (QNZ) in reversed-phase (RP) CEC. Influences of pH, composition of the buffer, acetonitrile content and the applied voltage on enantioseparation were examined. Enantiomers of the analytes investigated are well separated in acetonitrile/phosphate buffer mobile phases. Separation data on QNZ were compared to those on QN-bonded silica (QNS). Retention was longer but better enantioselectivity and resolution were obtained on QNZ than QNS.

• 전력전자학회논문지
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• 제23권2호
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• pp.147-151
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• 2018

Phase-shift fullbridge (PSFB) converter detects the current in the primary side for operation of the peak current mode controller (PCMC). The PCMC must used the slope compensation to solve the problem when the effective duty is over 0.5. The voltage response of PSFB converters has slower than that of buck converter because of slew interval even if the voltage controllers of two converters have same bandwidth. To overcome these problems, this work proposes a compensating method of current reference considering slew interval and fast response in the PSFB converter. The effectiveness of the proposed method is proven using the PSIM simulation and experiment.

• Journal of information and communication convergence engineering
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• 제9권1호
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• pp.59-63
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• 2011

Conventional noise reduction filtering schemes realize limited improvements of the peak signal-to-noise ratio (PSNR) in the low-level noisy images. The flatness degree and the edge information are effectively used to estimate the noise volume. We propose a noise estimator for reducing noise in the AWGN (additive white gaussian noise) corrupted images using three intermediate image maps (FGM(flatness gray map), FIM(flatness index map), NEM(noise estimate map)). The proposed noise estimator is fed into the conventional noise reduction filters as a pre-processor. The performance of noise reduction is tested in the various AWGN corrupted images.

• 전력전자학회논문지
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• 제21권1호
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• pp.27-33
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• 2016

A pulse-width modulation (PWM) method for common mode noise reduction in a PWM inverter connected to a single-phase grid is proposed in this study. The extensively used conventional switching method may experience common mode voltage problems, which generate current leakage and electromagnetic induction problems. In the proposed switching method, the neutral point of the output voltage is always fixed at both ends of the input voltage to reduce common mode noise. The validity of the proposed method is proven through simulation and experimental results.

• 전력전자학회논문지
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• 제21권2호
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• pp.117-125
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• 2016

In this paper, the inverter switch losses of BLDC motor for three types of PWM methods and power devices were analyzed. When the BLDC motor is driven at low currents, the inverter switch losses for MOSFET are low because MOSFET operates like resistance. However, the inverter switch losses for IGBT are higher than MOSFET due to its large turn-off losses. Moreover, synchronous rectification switching method is adaptable because MOSFET has 2-channel. So, MOSFET can be driven with more low impedance and losses. For low power inverter with MOSFET, the power losses of unified PWM are lower than that of unipolar and bipolar PWM. Proposed method and losses analysis results are verified by examination and simulation using Matlab/Simulink.