• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1515-1517
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• 2005

In this paper, we represent both occurrence reason of Surge-voltage and Leakage-current of AC drive system which is operated by Voltage-type PWM Inverter. It generates a compensating voltage which has the same amplitude as, but the opposite phase to, the common-mode voltage produced by the PWM inverter. The compensating voltage is superimposed on the inverter output by a common-mode transformer. As a result, the common-mode voltage applied to the load is canceled completely. The design method of the active common-mode noise canceler is also presented in detail. Therefore, we try to describe the method controling both of them and all of the proprieties are proved by our experiment.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.628-640
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• 2021

To investigate the supercavity geometry and gas flow structure for the supercavities with two closure types under the different flow conditions, an inhomogeneous multiphase model with the SST turbulence model was established, and validated by experimental results. The results show that two distinct regions exist inside the supercavity, which include the downstream flow region along the gas-water interface and the reverse flow region. For the twin-vortex supercavity, the internal gas leaks from the supercavity boundary by two paths: the supercavity surface and the two-vortex tubes. Increasing Froude number leads to more internal gas stripped from the supercavity surface. Two types of gas loss exist for the re-entrant jet supercavity with high Froude number, one type is the steady process of gas loss, and the major gas-leaking path is the supercavity surface rather than supercavity closure region. The other type is the unsteady periodic ejection, and the gas cluster of periodic ejection is merely a small part of the gas stored inside the supercavity.

• Restorative Dentistry and Endodontics
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• 제12권1호
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• pp.119-129
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• 1986

The purpose of this study was to evaluate the marginal leakage of glass ionomer cement with different cavosurface margins. 192 class V cavities were prepared on freshly extracted non-carious teeth and glass ionomer cement were inserted according to the manufacturer's instructions. Cavity preparations for this investigation were performed in four groups. The experimental specimens were made by packing the glass ionomer cement (Fuji Ionomer Type II G-C Co. Japan) into the prepared 192 cavities of four groups with different modes: Group I. - The 48 cavities with $90^{\circ}$ butt-joint cavosurface preparation and restored with glass ionomer cement. Group II. - The 48 cavities with butt-joint preparation modified by $135^{\circ}$ beveling the cavosurface in the dentin and restored with glass ionomer cement. Group III. - The 48 cavities with butt-joint preparation modified by cutting a chamfer in the dentin and restored with glass ionomer cement. Group IV. - The same 48 cavities as group I, and overfilled with glass ionomer cement beyond the cavosurface angle. And four groups above described divided into three subgroups by means of conditioning the cavity walls: Control group. - Glass ionomer cement filled in the prepared 64 cavities after being cleaned with a stream of tap water. Phosphoric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% phosphoric acid. Citric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% citric acid. All 192 specimens were immersed in the 2.0% basic fuchsin solution and subjected to thermal stress at one-minute intervals ($4{\pm}2^{\circ}C$ to $60{\pm}2^{\circ}C$) for 70 minutes before exposure to the dye. The specimens were sectioned ecclesiologically through the center of the restorations for different periods of immersion time, 24 hours, 7 days, 14 days 30 days. The sections were examined under a stereoscopic microscope. The results were as follows: 1. The degree of marginal leakage in group II and III was greater than that in group I and IV. 2. The degree of marginal leakage in phosphoric acid treatment group was similar with that in control group. 3. The degree of marginal leakage in citric acid treatment group was less than that in control group. 4. In all groups, the degree of marginal leakage in phosphoric acid treatment group was greater than that in citric acid treatment group. 5. There is no statistical difference of the degree of marginal leakage according to the immersion time in the dye solution.

• 한국압력기기공학회 논문집
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• 제5권1호
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• pp.9-13
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• 2009

The containment local leakage rate testing in nuclear power plants is performed in accordance with ANSI/ANS-56.8(1994) in Korea. Two methods, the make-up flow rate and the pressure decay, are used for LLRT. Though ANSI/ANS-56.8 does not define clearly the minimum test duration for the make-up flow rate method, it requires obtaining the data after reaching the stable condition. Thus the prerequisite stable condition for data acquisition and the test period for type "C" LLRT is differently applied to each NPPs. Therefore, this study presents a unified test criteria for data stabilization and test duration through experiments to improve the test reliability for type "C".

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.219-219
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• 2000

A Plate type pipe is used for heat exchange in radiator of a vehicle. The pipe has several rooms through which water flows and heat is dissipated into outside . In the case that there are small holes, cracks or some scratches on the plate, the radiators lost their functions due to Leakage. This may result in overheating of engine in a car. Thus, we need to perform the entire inspection of the plate type pipe in advance before assembling the radiator. In manufacturing process of the plate type pipe, the productive speed is very high and that may be performed continuously. So, there is no room to perform the outlook inspection by typical image processing techniques. This paper proposes a new method to inspect the outlook surface of the plate type pipe automatically with high speed. Especially, the sequential processing technique of an algorithm which detects defects on the surfaces of the plate type pipe is proposed for line scan camera which captures line image. To evaluate the inspection performance, a series of experiments is performed.

• Journal of Chest Surgery
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• 제30권2호
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• pp.236-240
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• 1997

긴 간격(longgap)의 A형 식도 폐쇄증을 가진 신생아의 치료는 복잡하고 아직까지 이견이 많아, 본래의 식도나 위, 소장, 대장 등을 이용한 치환술로 다양한 식도 재건술이 시행되고 있다. 저자는 long gap의 A형 식도 폐쇄증을 가진 재태기간 28주, 체중 1.2kg의 미숙아에서 식도 단단문합술을 시행하여 좋은 결과를 얻었기에 문헌고찰과 함께 보고하는 바이다. 1차 처치로 위루술를 하고 2차로 식도 단단문합을 시행하였다. 술후 제한된 문함부유출과 종격동염이 발생하였으나 흉관을 통한 적절한 배액(drainage)과 동시에 위루술을 통하여 문합부유출부위에 음압 (negative pressure)을 걸어 지속적 인 흘인(suction)으로 치료하여 호전되었다. 환아는 건강하게 퇴원하였으며 술후 4개월이 지난후 5.4kg으로 체중의 증가가 있었다.

• 한국정보통신학회논문지
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• 제21권1호
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• pp.223-228
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• 2017

본 연구에서는 광대역 펄스감마선 탐지센서 최적화 설계를 수행하고 설계결과를 기반으로 탐지센서를 제작하여 전기적 특성을 분석하였다. 탐지센서의 최적화 설계를 위해 펄스감마선의 시간에 따른 에너지 프로파일로 부터 입력 변수를 도출하고 탐지감도 제어회로를 통하여 출력전류 범위를 결정하였다. 도출된 변수를 바탕으로 N-type Epi Wafer 및 TCAD(Technology Computer Aided Design)로 설계하고 제작하였다. 제작된 탐지센서의 전기적 특성 분석 결과 -3.3V 전압에서 12pA의 누설전류와 -5V의 전압에서 완전 공핍화 되는 특성을 가짐을 확인하였다. 제작된 센서의 포항가속기연구소 TEST LINAC 시험결과 감마선 설정 선율의 펄스방사선에 대해 고감도의 광전류를 생성시킴을 확인하였다.

• 대한안전경영과학회지
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• 제17권2호
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• pp.117-127
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• 2015

This study investigated the smoke blocking and control systems for the safety of residents evacuation and for the prevention of smoke spread through the central corridor in the event of central corridor type of intelligent building fire. We offered additional ways of utilizing smoke ventilators and intake ventilation equipment and utilized CFD-based fire simulation program(FDS Ver.5.5.3) in order to analyze the effect. As a result, many differences in the smoke block effect, depending on the application of smoke ventilator and location of installation, was found. In addition, the result was found that larger effect was showed not in the case of application of smoke ventilator in central corridor only but application in fire room. The reason is that the smoke leakage is blocked primarily as air is flowed in the fire room through open door by operation of intake smoke ventilator in the public corridor and secondarily, the smoke leakage to the public corridor could be blocked as fire and smoke were released to the opened smoke ventilator continuously. Especially, the effect was maximized through complex interactions by applying smoke ventilator and intake ventilation equipment in corridor together rather than applying smoke ventilator and intake ventilation equipment independently. The proposed measure through this study shall be considered from architectural plan as one of ways for blocking from smoke spread to the central corridor in the central corridor type of intelligent building. In addition, flaws on regulation shall be established and supplemented.

• 조명전기설비학회논문지
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• 제16권6호
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• pp.22-29
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• 2002

무방향성 규소강판을 사용한 자기식 네온관용 변압기는 내구성이 좋은 반면에 용량에 따른 규소 강판의 무게가 무겁고 외형이 큰 관계로 네온관 설치 작업 시 상당히 불편한 점이 많다. 또한 네온관의 다양한 디스플레이 제어성면에서도 비합리적 이었다. 이를 개선하기 위한 방법으로 네온 트랜스포머의 전원장치 및 2차측 고압 출력부를 고속의 고주파 스위칭 파워 트랜지스터(MOSFET)를 이용하여 상용주파수 60［Hz］를 고속 스위칭 제어를 통하여 20［KHz］의 고주파로 변환시킨후, 네온관을 방전시키기 위한 고전압을 발생시키는 인버터식 네온관용 변압기를 구현하였다. 또한 네온관의 파손이나 누전으로 인한 화재나 인체 감전의 위험을 사전에 방지할 수 있는 보호회로 GFCI(Ground Fault Circuit Interrupter)를 제안 하였다.

• Tribology and Lubricants
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• 제18권4호
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• pp.273-278
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• 2002

Grease deterioration of mineral oil type grease was investigated using sealed deep groove ball bearings (6203) and bearing life test rig. The bearing test was performed under 3,000 rpm and 245 N radial load at 120。C. Grease taken ken tested bearings was checked in using certain evaluation methods, for example, oxidation induction time (OIT), FT-IR peak intensity, leakage .ate, bleeding .ate, total acid number. (TAN) and bearing noise increase. Within these test conditions, OIT, TAN, bleeding rate were changed gradually in accordance with bearing operating time and showed useful indices for deterioration of grease.