• Journal of the Society of Naval Architects of Korea
• /
• v.41 no.1
• /
• pp.88-93
• /
• 2004

Electrochemical impedance spectroscopy was used to evaluate the anticorrosive properties of resin(alkyd, epoxy, urethane) and pigment(hydroxy apatite(HAp), zinc potassium chromate(ZPC). red lead(RL)). The corrosion behavior of coatings applied on steel has been investigated during exposure to 0.5M-NaCl The anticorrosive performances of resins were found to depend on their chemical nature and decreased in the order of urethane > epoxy > alkyd resin coating. Hydroxy apatite and zinc potassium chromate pigment which have property to passivate the substrate showed relatively high anticorrosive performance.

• ETRI Journal
• /
• v.35 no.4
• /
• pp.603-609
• /
• 2013

In this paper, we present a 600-V reverse conducting insulated gate bipolar transistor (RC-IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC-IGBT uses the deep reactive-ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC-IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2013.11a
• /
• pp.55-56
• /
• 2013

소방보호복의 열보호특성을 정확히 파악하는 것은 보호복 개발 뿐만 아니라 화상에 의한 부상 방지 및 생명 보호라는 측면에서 매우 중요하다. 하지만 대부분의 경우 고열유속 조건에서 시험을 수행하여 시편의 파괴가 발생하기 쉽고, 그에 의해 제대로 된 결과를 얻어낼 수 없는 경우가 많다. 따라서 본 연구에서는 저열유속 조건의 복사열 노출시 열보호성능을 효과적으로 제시할 수 있는 지표 및 측정 방법을 기존 RPP (Radiant Protective Performance) 측정방법을 개선하여 제안하였다. 또한 실험을 통해 여러 가지 보호성능지표들의 관계를 파악하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.259-262
• /
• 2009

IEC 61850 based substation automation system mainly consists of human machine interface and a various of IEDs in charge of protective and control functions of the substation. Both of them should require the performance verification of IEC 61850 communication services because their communication relation is the same as client and server throughout the digital network. This paper shows a research result on the testing method of basic communication interface of the IEC 61850 based client, which was implemented by the analysis of real communication between HMI and IED of IEC 61850 based substation automation system and refereed to IED IEC 61850 conformance test procedures.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.617-618
• /
• 2012

Recently as the inactive response characteristics of the existing RCD(Residual Current protective Device) used on low voltage power distribution system, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore, this paper is proposed a prevention apparatus using neutral line voltage and semiconductor switching devices for the prevention of electrical disasters in low voltage power distribution system caused by overload or electric short circuit faults. The proposed prevention apparatus confirms the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker(RCD) through various operation performance analysis.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.4
• /
• pp.444-450
• /
• 2008

There are several ways to bond to building grounding systems for reducing GPR(ground potential rise) and EMI resulting from power system faults or lightning stroke to building. In order to verify effective bonding practice, the GPR and voltage of equipment due to the direct stroke to building are calculated with ATP-EMTP model for transformer, transmission line and MOV(Metal oxide varistor). The simulated model shows a satisfactory accuracy compared with experimental result for the $8/20{\mu}s$ simulated current pulse. It is observed that separate grounding can cause dangerous voltage to the building equipment and the performance of surge protective device can improve when it is installed to the protected equipment in distance as short as possible.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.388-390
• /
• 2004

디지털 보호계전기의 성능 검증에 있어서 RTDS(Real Time Digital Simulator)와 같은 디지털 시뮬레이터를 사용하는 경우가 점점 증가하고 있다. 특히 보호계전기의 동특성(Dynamic Performance) 시험에 있어서는, 디지털 시뮬레이터를 이용한 성능 검증이 거의 필수적이다. 본 논문에서는 디지털 보호계전기 중 거리계전기의 Reach Test에 있어서 성능 검증에 사용할 계통 모델 선정 방안을 PSCAD/RTDS에서의 구현 관점에서 기술하고 있다. 양단 전원을 가지는 4모선 2회선 송전선로를 Bergeron 모델을 이용하여 모델링하고, 모델의 유효성을 귀납적인 방법을 사용해서 검증하는 방안을 제시하고 있다.

• Journal of the Korean Society of Industry Convergence
• /
• v.26 no.4_2
• /
• pp.679-686
• /
• 2023

According to the PSPC (Performance Standard for Protective coatings) rule, the edge preparation must keep 2R or 3-pass grinding. The stiffener plate edge grinding of the ship inside is manually progressed by worker and worked with just one pass grinding. In addition, the poor working condition cause grinding workers to avoid working in them, and the quality is determined by the skill-level of a worker. This research developed optimal tool for edge milling. In order to milling various collar plates edge, this research developed vision system that can recognize the edge points and it developed a program that operator can adjust the amount of cutting and speed, and add various features so that milling quality would be improved. So, this research focused on overcoming the difficulties in working condition and development of automated milling machine for ship stiffener plate.

• Journal of Astronomy and Space Sciences
• /
• v.41 no.1
• /
• pp.17-23
• /
• 2024

The safety of electronic components used in aerospace systems against cosmic rays is one of the most important requirements in their design and construction (especially satellites). In this work, by calculating the dose caused by proton beams in geostationary Earth orbit (GEO) orbit using the MCNPX Monte Carlo code and the MULLASSIS code, the effect of different structures in the protection of cosmic rays has been evaluated. A multi-layer radiation shield composed of aluminum, water and polyethylene was designed and its performance was compared with shielding made of aluminum alone. The results show that the absorbed dose by the simulated protective layers has increased by 35.3% and 44.1% for two-layer (aluminum, polyethylene) and three-layer (aluminum, water, polyethylene) protection respectively, and it is effective in the protection of electronic components. In addition to that, by replacing the multi-layer shield instead of the conventional aluminum shield, the mass reduction percentage will be 38.88 and 39.69, respectively, for the two-layer and three-layer shield compared to the aluminum shield.

• The Korean Journal of Malacology
• /
• v.24 no.2
• /
• pp.131-136
• /
• 2008

Growth and survival of the spat of arkshell, Scapharca broughtonii were investigated for the improvement of survival in intermediate culture with different shape of protective net and type of preventive net of spat loss. The growth performance of the spat of arkshell was observed for 60 days by using different forms of protective net, as the exposure form with an average shell length of $12.8{\pm}3.2$ mm(P<0.05), the fish pot form with $12.2{\pm}3.5$ mm, the cylinder form with $11.9{\pm}3.8$ mm and the last one is the rectangular form with $10.9{\pm}3.7$ mm. Their numerical value did not show any marked difference with each other. But in case of survival rate, the fish pot form showed highest survival rate which is 43.7% and the significantly lowest was showed by the exposure form, which is 5.4%(P<0.05). The cylinder form and rectangular form showed 41.2 and 31.6% respectively. And then the growth of the spat of arkshell was observed for 163 days by rearing in a sort of preventive net, the first group was in a blackout curtain with average shell length of $13.9{\pm}3.1$ mm, the next group was in a balsam pear net with $12.9{\pm}3.0$ mm, in a polyethylene net with $11.8{\pm}3.1$ mm and the control with $12.6{\pm}3.3$ mm which was not installed by preventive net of spat loss. The survival rate was 91.5% in a blackout curtain, 90.1% in a polyethylene net, 88.5% in a balsam pear net and 61.5% in a controlled group. It is seen that the highest growth and survival rate were observed in a fish pot form and cylinder form. These results were a little bit difference from those of the spat of arkshell cultured in the form of different preventive nets. There was no significant difference in survival rate in relation to the sorts of preventive net against carrying-away, but there was a difference in survival rate by more than 30% as against the non-installed controlled group. We expect that survival rate would be highly improved in intermediate culture carried out with fish pot form and cylinder form of protective net and preventive net of spat loss.