• Progress in Superconductivity
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• v.7 no.1
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• pp.46-51
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• 2005

We have developed control electronics to operate flux-locked loop (FLL), and analog signal filters to process FLL outputs for 64-channel Double Relaxation Oscillation SQUID (DROS) magnetocardiography (MCG) system. Control electronics consisting of a preamplifier, an integrator, and a feedback, is compact and low-cost due to larger swing voltage and flux-to-voltage transfer coefficients of DROS than those of dc SQUIDs. Analog signal filter (ASF) serially chained with a high-pass filter having a cut-off frequency of 0.1 Hz, an amplifier having a gain of 100, a low-pass filter of 100 Hz, and a notch filter of 60 Hz makes FLL output suitable for MCG. The noise of a preamplifier in FLL control electronics is $7\;nV/{\surd}\;Hz$ at 1 Hz, $1.5\;nV/{\surd}\;Hz$ at 100 Hz that contributes $6\;fT/{\surd}\;Hz$ at 1 Hz, $1.3\;fT/{\surd}\;Hz$ at 100 Hz in readout electronics, and the noise of ASF electronics is $150\;{\mu}V/{\surd}\;Hz$ equivalent to $0.13\;fT/{\surd}\;Hz$ within the range of $1{\sim}100\;Hz$. When DROSs are connected to readout electronics inside a magnetically shielded room, the noise of 64-channel DROS system is $10\;fT/{\surd}\;Hz$ at 1 Hz, $5\;fT/{\surd}\;Hz$ at 100 Hz on the average, low enough to measure human MCG.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.131-134
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• 1991

In order to determine an operating pattern of SLIM in an experimental MAGLEV vehicle, operating characteristics of SLIM are obtained using a disk type test facility. The test results are compared with the pre-estimated values. It is found that a closed loop control is required for operating at a constant slip-frequency condition which makes the normal force minimum.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.396-397
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• 2018

벡터제어는 V/F운전에 비해서 높은 기동 토크와 과부하시 효율적인 전류 제한이 가능한 장점으로 인하여 고성능이 요구되는 부하에 적용이 확대되고 있다. 하지만 출력전압이 V/F운전과 같이 주파수에 따라서 결정되지 않고, 모터파라미터와 D축전류에 의해 결정되므로 정격부하에서 출력전압이 작아지는 경우 출력전류가 정격전류 보다 지나치게 커지는 단점이 있다. 이러한 문제점을 해결하기 위해서 기존 약자속 운전에 적용되었던 전압제어기를 사용하여 출력전압을 제어하는 용도로 사용하고자 한다.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.2
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• pp.231-235
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• 1996

Bangladeshi indigenous chickens of mixed ages vaccinated twice at a three week interval with either conventional vaccines-$F_1$ (ocular) and M (mukteswar, Intramuscular), or heat resistant $V_4$ vaccine administered by either the ocular or oral routes, all showed satisfactory hemagglutination inhibition antibody (HI) responses and protection against Newcastle Disease (NCD) challenge persisting for four months. The antibody response to $F_1$ and M was higher than for $V_4$, which was similar whether administered by the ocular or oral routes. All vaccinated treatments have a significant level of protection compare to the control group (p<0.01). No significant difference (p>0.05) in the protection against controlled challenge with virulent NCD virus was found between vaccinated groups.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.217-220
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• 2003

In this paper, Inverter drives adopting 2 phase space vector SRP-PWM (Separately Randomized Pulse Position PWM) with fixed switching frequency is proposed. The proposed 2 phase space vector SRP-PWM scheme is based on the 3 phase SRP-PWM. In the proposed SRP-PWM scheme, each of two phase pulses is located randomly in each switching interval. The experimental results show that the voltage and acoustic noise harmonics are spread to a wide band area. Also, the performance of the proposed 2 phase SRP-PWM and the conventional center aligned SVM are compared to each other. In resuit, the speed response is nearly simitar to each other from the viewpoint of the v/f constant control.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.558-560
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• 2019

범용 인버터는 계통 전원의 전압 강하 또는 정전 발생 시, 정류기의 직류단 전압이 감소하여 인버터 고장(fault)이 발생한다. 보호 동작으로서 인버터는 일시적으로 전원 공급이 이루어 지지 않는 상태에서 제어 기능 및 관리가 이루어 질 수 있도록 Ride-Through 운전을 수행한다. 고장 발생 없이 제어 시스템 상태를 유지하여 전원 복구 후, 빠른 재기동이 가능하다. 본 논문에서 V/f 제어를 사용하는 범용 인버터를 고려한 Ride-Through 방법으로 KEB(Kinetic Energy Backup) 운전을 제안한다. KEB 운전은 순시 정전에 의한 인버터 고장 방지를 위해 요구되는 에너지를 계산하고 슬립 주파수를 조절하여 회생 운전을 통해 인버터의 직류단 전압을 일정하게 유지한다. 제안한 방법은 실험을 통해 유효성을 검증한다.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.483-486
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• 2003

This paper presents a small capacitance measuring circuit for capacitive sensors. The proposed circuit consists of sinewave generator, detector and demodulator. Results of experiments are shown that the circuit can be able to measure small capacitance exiting in a capacitive sensor filled with a vegetable oil. The sensitivity of the circuit is from 0.4V/pF to 4V/pF and the resolution is from 0.0025 pF to 0.00025 pF.

• The Korean Journal of Mycology
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• v.24 no.1 s.76
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• pp.49-55
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• 1996

This study was conducted to find out antifungal activities of entomopathogenic fungus, Metarhizium anisopliae, against phytopathogenic fungi, Fusarium oxysporum, Botrytis cinerea and Alternaria solani. M. anisopliae was confirmed its antagonistic effect through mycelial inhibition zone of phytopathogenic fungi by culture filtrate of the antagonist. The filtrate (30%: v/v) inhibited the conidial germination of B. cinerea and F. oxysporum to 21.5% (control: 88.2%) and 53.0% (control: 78.6%), respectively and delayed the start of spore germination about 8hours. Microscopic observations proved that the addition of 10% culture filtrate of M. anisopliae restricted the growth of phytopathogenic fungus, F. oxysporum, to the formation of chlamydospore. From these results, we concluded that an addition effect of the filtrate from M. anisopliae on culturing F. oxysporum was fungistatic.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.419-428
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• 2020

The flow past a wall mounted square cylinder, a typical and basic shape of building, bridge or offshore structure, was simulated using URANS computation through adoption of three turbulence models, namely, the k-ε model, k-ω model, and the v²-f model. It is well known that this flow is naturally unstable due to the Karman vortex shedding and exhibits a complex flow structure in the wake region. The mean flow field including velocity profiles and the dominant frequency of flow oscillation that was from the simulations discussed earlier were compared with the experimental data observed by Wang et al. (2004; 2006). Based on these comparisons it was found that the v²-f model is most accurate for the URANS simulation; moreover, the k-ω model is also acceptable. However, the k-ε model was found to be unsuitable in this case. Therefore, v²-f model is proved to be an excellent choice for the analysis of flow with massive separation. Therefore, it is expected to be used in future by studies aiming to control the flow separation.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.575-586
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• 2000

In this study, adaptation of compomer to saliva contaminated dentin was evaluated with scanning electron microscope(SEM) and confocal laser scanning microscope(CLSM). For the SEM study, the occulusal surfaces of thirty two molar teeth were grounded to exposure dentin surfaces. The specimen were randomly assigned to control and three experimental groups with four samples in each group. In control group, Dyract and F-2000 compomer were bonded on the specimens according to the manufactures direction. Experimental groups were subdivided into three groups. They were contaminated with saliva on dentin surfaces ; Experimental group 1 : Saliva was dried with compressed air. Experimental group 2 : Saliva was rinsed with air-water spray and dried. Experimental group 3 : After polymerization of an adhesive, they were contaminated with saliva, and then saliva was rinsed with air-water spray and dried. Dyract and F-2000 compomer were bonded on saliva-treated dentin surfaces. The interfaces between dentin and compomer were observed with SEM. For the CLSM study, Class V cavities were prepared in buccal and ligual surfacess of thirty two molars. The specimens were divided into control and experimental groups. Class V cavities in experimental group were contaminated with saliva and those surfaces in each experimental groups received the same treatments as for the SEM study. Cavities were applied Prime & Bond 2.1 and F-2000 compomer primer/adhesive that were mixed with fluorescein, and then were filled with Dyract and F-2000 compomer. Specimens were embedded in transparent acrylic resin and sectioned buccolingual1y with diamond wheel saw, and then mounted on cover slide for CLSM study. The interface between cavity and compomer was observed by fluoresence imaging with a CLSM. The results were as follows : 1. In SEM exammination of Dyract group, control group, experimental group 2, 3 showed close adaptation to dentin and hybrid layer of $3{\sim}4{\mu}m$ diameter. Interfacial gap between compomer and dentin in experimental group 1 was wider than in control group. 2. In SEM examination of F-2000 group, adaptation to dentin of control group was closer than Dytact control group, but hybrid-like layer was not observed. Interfacial gap between compomer and dentin in experimental group 1 was wider than in Dyract experimental group 1. 3. In dissolution specimens of Dyract and F-2000 group, resin tags penetrated through dentinal tubules in control group and experimental group 1 and 3, but the penetration of resin tag was irregular and partial in experimental group 1. 4. In CLSM exammination of Dyract and F-2000 group, adhesive patterns of control and experimental groups showed same as in SEM. This result suggests the treatment methods, rinsing & drying, repeating all adhesive procedures, will produce good effect on adaptation of compomer to dentin if the dentin surface or polymerized adhesive is contaminated by saliva.