• Journal of Advanced Marine Engineering and Technology
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• 제39권5호
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• pp.527-535
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• 2015

As a new technical approach, a hydraulic and magnetic clamp device was attempted to realize a magnetic clamp crane system that uses 8 simultaneously actuating individual hydraulic cylinders. Through this approach, a Sr type of ferritic permanent magnet ($SrO{\cdot}6Fe_2O_3$), not the previously employed electro-magnet, was utilized for the purpose of lifting and transporting the heavy weighted and oversized curved steel plates used for manufacturing the ships. This study is aimed at manufacturing and developing the hydraulic magnetic clamp prototype, which is composed of three main parts - the base frame, cylinder joint, and magnet joint - in order to safely transport such curved steel plates. Furthermore, this research was pursued to conduct a performance evaluation as to the prototype manufacture and acquire the planned quantity value and the development purpose items. The most significant item for a performance evaluation was estimated for the magnetic adhesive force (G) and in this process, a ferritic permanent magnet (Sr type) with 3700~4000 G of residual induction (Br) and 2640/2770 Oe of coercive force (Hc) was utilized. In addition, other relevant items such as hoist tension (kN), transportation time (sec), and the applied load (Kgf) exerted on the hydraulic cylinders were also evaluated in order to acquire the optimum quantity value. As a result of the evaluation, the relevant device turned out to be suitable for safely transporting the curved steel plates.

• 한국해양공학회지
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• 제29권4호
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• pp.322-330
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• 2015

As a new technical approach, a hydraulic and magnetic clamp device was developed to realize a magnetic clamp crane system by simultaneously actuating eight individual hydraulic cylinders. In this approach, an Sr-type of ferritic permanent magnet (SrO· 6Fe₂O₃), rather than the previous electromagnet, was utilized for the purpose of lifting and transporting the large curved steel plates used for manufacturing ships. This study had the goal of developing and manufacturing a hydraulic, magnetic clamp prototype composed of three main parts, including the base frame, cylinder joint, and magnet joint, in order to safely transport curved steel plates. Furthermore, this research included a performance evaluation of the manufactured prototype and acquired the purposed quantity value in the performance test. The most significant item, the magnetic adhesive force (G), was evaluated in a performance test, which utilized a ferritic permanent magnet (Sr type) with 3700~4000 G of residual induction (Br) and 2640/2770 Oe of coercive force (Hc). In particular, relevant items such as the hoist tension (kN), transportation time (s), and applied load (Kgf) on the hydraulic cylinders were also evaluated in order to determine the optimum values.

• 대한전자공학회논문지SD
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• 제45권10호
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• pp.1-6
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• 2008

고전압 MOSFET에서 스냅백 이후의 유지 전압은 구동전압에 비해 매우 작아서 고전압 MOSFET이 파워 클램프로 바로 사용될 경우 래치업 문제를 일으킬 수 있다. 본 연구에서는 Drain-Extended PMOS를 이용하여 래치업 문제가 일어나지 않는 구조를 제안하였다. 제안된 구조에서는 래치업의 위험을 피하기 위해 소자가 스냅백이 일어나지 않는 영역으로 동작 영역을 제한하였다. $0.35\;{\mu}m$ 60V BCD(Bipolar-CMOS-DMOS) 공정을 사용하여 제작된 칩을 측정한 결과를 통해 제안된 기존의 gate-driven 구조의 LDMOS(Lateral Double-Diffused MOS)를 사용한 ESD 파워 클램프에 비해 500% 성능향상(강인성)이 있게 된 것을 알 수 있다.

• 한국균학회지
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• 제15권4호
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• pp.250-253
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• 1987

원형질체내에 외래유전물질 도입에 의한 균주 개발의 가능성 검토의 일환으로 사철느타리의 원형질체로부터 핵을 분리하여 느타리의 원형질체내로 전이하여 얻은 결과는 다음과 같았다. 1. 핵전이주는 크게 3가지 type으로 구분되었는데 type 1은 아주 빠른 균사생장과 clamp connection를 형성하지 않으며 CM+benomyl에서 균총분리가 나타남으로서 이질이배체로 사료되었다. type 2는 주된 핵전이주로서 모균주와 비슷하거나 다소 빠른 균사생장과 clamp connection을 지녀 자실체를 형성하였으며 heterokaryon으로서 원형질체 융합주와 유사하였다. 그러고 type 3은 핵 또는 염색체 단편의 전이로 clamp connection를 지니지 않고 아주 느리거나 MM에서 생육이 거의 불가능한 균주였다. 2. 핵전이주 및 모균주를 전기영동법으로 esterase 동위효소 pattern을 조사한 결과 핵전이주는 모균주와 구별되었는데 type 1인 이질이배체는 새로운 band를 나타내었으며, type 2와 type 3은 모균주들을 합한 것으로 보였다.

• 조명전기설비학회논문지
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• 제24권5호
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• pp.136-144
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• 2010

본 논문에서는 2개의 액티브 클램프 포워드 컨버터로 구성된 투 스위치 인터리브 액티브 클램프 포워드 컨버터를 제안하고자 한다. 제안된 컨버터는 단지 2개의 스위치만을 필요로 하며, 각 스위치는 상호 보조스위치로서 동작하기 때문에 회로의 구성이 간단하고 저비용의 용이한 제어를 특징으로 한다. 아울러 부가적인 공진 인덕터로 인하여 데드타임 동안에 영전압 스위칭 동작이 가능하다. 제안된 컨버터는 인터리브 동작으로 인하여 출력 전압 및 전류 리플이 저감되므로 출력 필터의 크기를 줄일 수 있으며, 그로인하여 컨버터의 부피를 감소시킬 수 있다. 본 논문에서는 제안된 투 스위치 인터리브 액티브 클램프 포워드 컨버터의 모드별 해석과 특성을 논의하였으며, 160[W]급 시작품을 제작하여 그 타당성을 검증하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제11권1호
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• pp.15-20
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• 2007

To investigate whether hydrogen peroxide($H_2O_2$) affects intestinal motility, pacemaker currents and membrane potential were recorded in cultured interstitial cells of Cajal(ICC) from murine small intestine by using a whole-cell patch clamp. In whole cell patch technique at $30^{\circ}C$, ICC generated spontaneous pacemaker potential under current clamp mode(I=0) and inward currents(pacemaker currents) under voltage clamp mode at a holding potential of -70 mV. When ICC were treated with $H_2O_2$ in ICC, $H_2O_2$ hyperpolarized the membrane potential under currents clamp mode and decreased both the frequency and amplitude of pacemaker currents and increased the resting currents in outward direction under voltage clamp mode. Also, $H_2O_2$ inhibited the pacemaker currents in a dose-dependent manner. Because the properties of $H_2O_2$ action on pacemaker currents were same as the effects of pinacidil(ATP-sensitive $K^+$ channels opener), we tested the effects of glibenclamide(ATP-sensitive $K^+$ channels blocker) on $H_2O_2$ action in ICC, and found that the effects of $H_2O_2$ on pacemaker currents were blocked by co- or pre- treatment of glibenclamide. These results suggest that $H_2O_2$ inhibits pacemaker currents of ICC by activating ATP-sensitive $K^+$ channels.

• Journal of Chest Surgery
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• 제14권1호
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• pp.1-8
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• 1981

Alterations in serum enzymes were studied in twenty-five patients who underwent open heart surgery in N.M.C. during the period from June 1979, to Feb. 1980. There were fifteen congenital and ten acquired heart diseases. In all patients, Rygg-Kyvsgaard five head roller pump and Polystan bubble oxygenator were used and serial determination of total level of Creatine phosphokinase [CPK], Lactic dehydrogenase [LDH], Glutamic oxaloacetic transaminase [SGOT] were made preoperatively, operation day [just after aortic clamp release, 2 hrs later, 4 hrs later, 6 hrs later], and postoperative days up to 5th day. Immediate postoperative clinical courses were also evaluated. Twenty-five patients were divided into two groups: Group A[13] was cardiopulmonary bypass time more than 95 minutes and aortic clamp time more than 45 minutes. Group B[12] was cardiopulmonary bypass time less than 95 minutes and aortic clamp time less than 45 minutes. The peak levels of SGOT, LDH in Group A were more significantly elevated than Group B [P<0.05]. But peak levels of CPK were not significant between two groups. In the view of clinical evaluation, poor clinical courses were more frequent in Group A [54%] than Group B[8%].

• 한국유체기계학회 논문집
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• 제15권4호
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• pp.12-18
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• 2012

This study was performed to found out the deviations for clamp-on type ultrasonic flowmeter installed in downstream of valves. It was selected three types of two-path flowmeter mainly used for K-water as test. Experiment carried out to confirmed characteristics of deviation depending on the sensor location, straight pipe length and maker for 1-path, 2-path and 4-path combined 2-path flowmeter. It was selected two kinds of valves with 100 % and 50 % opening, butterfly valves and gate valves, for flow disturbance factor. Finally, we suggested number of sensors by maker, straight pipe length and installed location of sensors satisfying the tolerance depending on the experiment results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2020-2022
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• 1997

An active clamp forward converter is proper for minimization and basically makes high efficiency of the system because of soft switching type. Especially, when applied to forward converter, it widens the control range of duty ratio and is suitable for high input voltage. In other hand, the current doubler has high utility efficiency of transformer and reduces output current ripple because it always transfers the power through the transformer and has two inductor with opposite slope. So, this paper explained the conduction mode of an active clamp forward converter with the current doubler rectifier.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.453-457
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• 1996

DC/DC converter is widely used in computer, electronic communication and industrial apparatus where the regulated dc supply is needed. FB-ZVS converter is suitable for high-power, high-frequency and constant frequency control. Because the voltage stress of the diode rectifier is high due to the ring effect, the clamp circuit is essential to reduce the voltage stress. The nondissipative active clamp circuit eliminates ring effect. Analysis of FB-ZVS converter and the validity of the active clamp circuit are studied through the simulation, and the experimental results show the superior characterics of the proposed system.