• 전력전자학회논문지
• /
• 제18권3호
• /
• pp.263-269
• /
• 2013

The flyback converter has been applied widely in isolated DC/DC power converters because this converters employ a single MOSFET switch. The leakage inductance should be minimized for high efficiency of flyback converter. but in reality, it is very difficult. Namely, The Snubber circuit is essential to recover the leakage inductance stored energy when the switch is turn off. Flyback Converter typically operates in DCM mode and when switch is turn off in hard switching, this hard switching action results in a high power losses and switching stresses. In order to overcome these problems, a novel soft switching flyback converter using resonant snubber circuit is proposed in this paper. The resonant snubber circuit is composed of the transformer leakage inductance and a capacitor. To verify and confirm the proposed resonant snubber circuit, PSIM simulation and hardware prototype are implemented. Simulation and Experimental results indicate that the proposed resonant snubber circuit is effective.

• 한국멀티미디어학회논문지
• /
• 제13권1호
• /
• pp.93-101
• /
• 2010

USB 메모리는 휴대성과 가격대비 고용량을 제공하는 이동형 저장매체로 많은 사용자를 확보하고 있다. 이러한 USB 메모리의 분실 및 도난을 통하여 개인 정보 유출 사건이 증가함에 따라 보안USB 솔루션이 개발되어 사용자들에게 제공되고 있다. 하지만 보안USB의 사용 불편함과 보안 취약점이 발견되고 있어 더욱 안전하고 사용자 편의를 제공하는 보안 솔루션의 필요성이 대두되고 있다. 본 논문은 기존의 이동형 저장매체를 위한 보안 솔루션을 분석하고 더욱 안전하고 사용자 편의성을 제공하는 보안 솔루션을 제시하고자 한다.

• 유공압시스템학회논문집
• /
• 제4권3호
• /
• pp.1-6
• /
• 2007

The leakage generated from the clearance between the cylinder bore and the piston is one of the most serious problems in the hydraulic piston pump, and it even results in terrible decrease of the volume efficiency at a great velocity and high pressure. In this paper, the lubrication characteristic of the hydrostatic slipper bearing equipped in the hydraulic piston pump has been worked out by experimentation with three model bearings of different shape. Preparatory to this, not only the three models of piston-slipper were designed, but the corresponding experimental apparatus were also manufactured. As a result, it was verified that, according to the supply pressure, the hydrostatic bearing part of the slipper is severely affected by the pocket pressure, land pressure, oil film thickness, and leakage flow.

• 전기학회논문지
• /
• 제62권6호
• /
• pp.876-880
• /
• 2013

The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The principal factor of the fire is electric arc or spark accompanied with such electric faults. Earth Leakage Circuit Breaker (ELB) and Molded_case Circuit Breaker (MCCB), that is, Residual Current Protective Devices (RCDs) used on low voltage distribution lines cut off earth leakage and overload, but the RCD can not cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied in low voltage distribution panel are prescribed to rated breaking time about 30[ms] (KS C 4613), the RCDs can't perceive to the periodic electric arc or spark of more short wavelength level. To improve such problems, this paper studies on an arc fault circuit interrupter (AFCI) using the distorted voltage wave in electric arc faults. The proposed voltage sensing type AFCI is an electrical fire prevention apparatus of new conception that operates a circuit breaker with sensing the instantaneous voltage drop of line voltage at electrical faults occurrence. The proposed AFCI is composed of control circuit topology using some semiconductor switching devices. Some experimental tests of the proposed AFCI confirm practicality and the validity of the analytical results.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 추계 학술논문 발표대회
• /
• pp.221-222
• /
• 2017

An analysis of the current water leak status of understand structure (underground parking lots, staircases, plumbing systems, water reservoirs, etc.) of multi-family housing in South Korea shows that water leaks are found from cracks in all areas of the underground structure caused by the degradation environment (water pressure by underground water, humidity, temperature, earth pressure, soil behaviour and vibration, etc.), which result in various problems, including mold, malodour, debonding of finishing materials, exfoliation, breakout, water leaks in electrical boxes, efflorescence, sedimentation of calcium hydroxide, decoloration, rusting, damages and pollution among others. Therefore, this study aims to analyse the current status of water leaks in underground structure and use the results as the basic data for developing a standard guideline for water leaks and maintenance by parts of the underground structure of multi-family housing.

• Journal of information and communication convergence engineering
• /
• 제17권2호
• /
• pp.161-165
• /
• 2019

In this study, zinc tin oxide (ZTO) thin-film transistors are researched to observe the correlation between the barrier potential and electrical properties. Although much research has been conducted on the electronic radiation from Schottky contacts in semiconductor devices, research on electronic radiation that occurs at voltages above the threshold voltage is lacking. Furthermore, the current phenomena occurring below the threshold voltage need to be studied. Bidirectional transistors exhibit current flows below the threshold voltage, and studying the characteristics of these currents can help understand the problems associated with leakage current. A factor that affects the stability of bidirectional transistors is the potential barrier to the Schottky contact. It has been confirmed that Schottky contacts increase the efficiency of the element in semiconductor devices, by cutting off the leakage current, and that the recombination at the PN junction is closely related to the Schottky contacts. The bidirectional characteristics of the transistors are controlled by the space-charge limiting currents generated by the barrier potentials of the SiOC insulated film. Space-charge limiting currents caused by the tunneling phenomenon or quantum effect are new conduction mechanisms in semiconductors, and are different from the leakage current.

• Nuclear Engineering and Technology
• /
• 제51권5호
• /
• pp.1195-1208
• /
• 2019

This paper introduces a new two-step procedure for PWR depletion analyses. This procedure adopts the albedo-corrected parameterized equivalence constants (APEC) method to correct the lattice-based raw cross sections (XSs) and discontinuity factors (DFs) by accounting for neutron leakage. The intrinsic limitations of the conventional two-step methods are discussed by analyzing a 2-dimensional SMR with the commercial DeCART2D/MASTER code system. For a full-scope development of the APEC correction, the MASTER nodal code was modified so that the group constants can be corrected in the middle of a microscopic core depletion. The basic APEC methodology is described and color-set problems are defined to determine the APEC functions for burnup-dependent XS and DF corrections. Then the new two-step method was applied to depletion analyses of the SMR without thermal feedback, and its validity was evaluated in terms of being able to predict accurately the reactor eigenvalue and nodal power profile. In addition, four variants of the original SMR core were also analyzed for a further evaluation of the APEC-assisted depletion. In this work, several combinations of the burnup-dependent and -independent XS and DF corrections were also considered. The results show that the APEC method could enhance the nodal equivalence significantly with inexpensive additional costs.

• Journal of Digestive Cancer Research
• /
• 제11권2호
• /
• pp.66-76
• /
• 2023

Endoscopy is an important noninvasive procedure for patients with gastrointestinal problems. However, surgical techniques are shifting to laparoscopic surgery, and changes in endoscopic findings after laparoscopic surgery differ from those after previous surgical methods. Postoperative endoscopic findings differ from normal anatomical structures, and findings reportedly vary depending on the type of surgical technique. Therefore, we aimed to summarize the surgical and endoscopic findings for each surgical method from the surgeon's point of view. The causes of gastric emptying delay, bleeding, afferent loop syndrome, or anastomosis leakage occurring after gastric cancer surgery can be identified via upper gastrointestinal endoscopy that is relatively less invasive than the surgical method. Regarding postoperative anastomosis leakage, endoscopy can directly evaluate the degree of leakage at the anastomosis site more accurately than computed tomography and enable immediate intervention. As endoscopy is less invasive than the surgical method, patients can be evaluated and treated more safely. However, coordination between the surgeon and the endoscopist is necessary to perform the procedures effectively. Therefore, reviewing the changes in surgical and endoscopic findings is important.

• 한국음향학회:학술대회논문집
• /
• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
• /
• pp.35-38
• /
• 2004

In this paper, we investigate and analyze the problems encountered in frame-based estimation of TDOA(Time Difference of Arrival) using CPSP function. Spectral leakage occurring in framing of a speech signal by a rectangular window makes estimation of CPSP spectrum inaccurate. Framing with a Hamming window to reduce the spectral leakage effect distorts the signal due to the different weighting at temporally same sample, which make the TDOA estimation using CPSP function inaccurate. In this paper, we solve this problem by reducing the dynamic range of the spectrum of a speech signal with preemphasis. Experimental results confirm that the framing of pre-emphasized microphone output with a rectangular window shows higher success ratio of TDOA estimation than any other framing methods.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 E
• /
• pp.2405-2407
• /
• 1999

In recent, the application of polymeric insulators for outdoor is significantly increasing. These materials have shown good performance in service, but had disadvantages under long-term exposure to contamination and moisture, resulting in some problems. Thus, this study concentrated on the development of technique evaluating the insulating status. Experiment was referred to lEC publ. 587, with data aquisition system to monitor leakage current. The components of leakage current investigated were waveform and 3rd harmonic. FFT was conducted for the analysis of harmonic components. The distortion of waveform with application time of voltage was evident, and so the 3rd harmonic component.