• 한국수소및신에너지학회논문집
• /
• 제28권2호
• /
• pp.121-128
• /
• 2017

For an investigation on the effect of the shape of electrodes in alkaline water electrolysis, two kinds of stack with circular and square electrode array are used to visualize both for behaviors of hydrogen bubble around the electrodes and for measurements of hydrogen production from these two stacks. The electrolytes for the hydrogen production experiment were applied for 20 wt%, 25 wt%, 30 wt% and 35 wt% of KOH alkaline aqueous solutions. As a result, the adhesion length of bubbles attached around the square electrode in the visualization experiment was found to be 1.7 times longer compared with the attached around the circular electrode. In the hydrogen production experiments, the volume of hydrogen production of the stack by using circular electrode array was approximately 3% more than that of the stack with square electrode array. These observations may be caused by the effect of the bubbles attached to the around the electrodes obstructing mass transfer such as hydrogen exhaust and electrolyte supply.

• 한국터널지하공간학회 논문집
• /
• 제21권2호
• /
• pp.267-278
• /
• 2019

터널의 안정적인 시공을 위해 터널 굴진 도중 터널 전방의 이상영역을 확인할 수 있는 다양한 방법의 터널전방예측 기법들이 사용되고 있다. 터널전방예측 방법 중 하나인 2전극 전기비저항 탐사(Pole-Pole array)는 터널직경 5배 이내의 함수대, 연약대 등을 확인하기 위해 자주 사용되고 있다. 2전극 전기비저항 탐사 시 가장 중요한 것 중 하나는 원지반의 전기비저항값을 유추하는 것이며, 원지반의 전기비저항은 1) 지반과 전극의 접촉면적을 계산하고, 2) 그와 동일한 표면적을 가지는 반구형으로 가정하는 과정을 거쳐 얻어진다. 이러한 가정은 지반과 전극이 접촉하는 면적이 적고 충분한 거리가 떨어져야 한다. 하지만 전극의 크기, 형태 및 전극사이의 거리에 따라 실제 측정되는 저항이 달라지므로 이에 대한 정확한 평가가 필요하다. 따라서 본 연구에서는 전기비저항 탐사에서 주로 사용되는 원기둥형 전극의 크기와 전극사이의 거리에 따른 영향에 관한 이론식을 유도하고, 실험 연구를 통해 검증하였다. 이를 바탕으로 원기둥형 전극의 관입깊이가 반지름에 비해 큰 경우, 등가 반구형 전극의 가정을 사용하면 에러가 증가하므로 적용 시 주의해야 함을 확인하였다.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1998년도 추계학술대회 논문집
• /
• pp.48-53
• /
• 1998

In this paper, the new electrochemical machining method is proposed for the micro unit fabrication by using the point electrode tools. The precision shape control capacity is improved by using the point electrode method. It was observed that an electric discharge phenomenon occurs during the electrochemical machining process by using the spraying and torrent type electrolyte supply method.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.740-743
• /
• 2009

In this paper we proposed a new electrode design to get an enhanced luminous efficiency in AC PDP. The width and shape of the TTO electrode were varied, and the electro-optical properties such as luminance, power consumption, luminous efficiency were estimated with the variation of frequency, duty ratio and applied voltage. The discharge characteristics were investigated to explain the effect of the new electrode structure on the electro-optical properties.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2005년도 춘계학술대회논문집
• /
• pp.349-354
• /
• 2005

Recently, there are many equipment of electricity, electronics, and communication which need to grounding in the building. When the electric current flows into a certain grounding system in the same building, the potential rise of other grounding system is possible to be affected by its potential rise. This potential interference was affected by the surface potential, it is deeply related whit the electrode shape. In this paper, basic formula is deduced on the basis of both electrodes surface potential of grounding electrode in a source of the potential interference and groundidng electrode which receive the potential interference. Therefore the degree of potential interference as multiple groundidng electrode can be verified the simulated results by means of the simple model in advance. This is for investigating the grounding resistance of grounding electrodes, the experiment was performed with model-scale of the grounding system and the scaled model grounding system was to this experiment using a water tank of a stainless steel-hemisphere shape. since mesh electrodes have been widely in the general building, we're tried to analyze that this water tank model and it's simulation as well.

• 한국안전학회지
• /
• 제23권4호
• /
• pp.42-46
• /
• 2008

Ionizers are essential in various areas of manufacturing industries to protect electrostatic hazards and to reduce inferior products. For ion sources used in the charge neutralizers, there are corona discharge, soft X-ray, ultraviolet and glow discharge. Glow discharge has lots of attractive properties, such as lower discharge sustaining voltage, no generation of ozone, and so on. In this paper, we did an experimental study to trace the mechanism and stabilization of atmospheric pressure glow discharge using the several size and shape of electrodes. As an experimental result, to sustain conditions of atmospheric pressure glow discharge is that discharge voltage is 360V, discharge current is 12mA, apply frequency is 1kHz between electrodes when positive electrode is molybdenum(Mo) and negative electrode is copper(Cu). We confirmed that the mechanism and stabilization of atmospheric glow discharge is deeply concerned with the shape and material of electrode for discharge. Especially, glow discharge in atmospheric pressure was well generated and sustained according with the physical properties used electrode materials, example melting point, thermal conductivity, and etc.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.491-496
• /
• 2008

A HEV-relay plays a significant role as a mechanical switch which determines the operation of a gasoline engine or an electric motor in a hybrid electric vehicle (HEV). The HEV-relay has critical two problems in the operating process. First, the unstable current can occur in the operating process of the HEV-relay due to the severe bounce between moving and fixed electrode. Second, noises occur due to impact between electrodes in HEV-relay. In this research, spring properties such as stiffness and initial compression force, and electrode shape are designed to reduce the bounce time and noises caused by impact between moving and fixed electrode. The operating process of HEV-relay is simulated using LS-DYNA3D as explicit finite element code. The optimum spring properties are determined using the response surface method (RSM) as the design methodology, and the electrode shape is newly designed through the modifying the stiffness of moving and fixed electrode.

• 한국수소및신에너지학회논문집
• /
• 제23권3호
• /
• pp.256-263
• /
• 2012

We studied the degradation phenomenon of Pt catalyst in PEMFC. We used the electron microscope analysis technique including the ultra-microtome pretreatment method, FEG-SEM and TEM analysis methods for analysis of Pt nanoparticles. The Pt catalyst degradation is observed not only in electrode site but also in membrane site. We investigated these various degradation phenomena. The cathode electrode layer thickness is reduced. The size of the catalyst is increased much larger than initial size in membrane site. The catalyst moved from electrode layer to the electrolyte membrane. The rounded shape of catalyst was changed to the polygon. As a result, we found that the catalyst degradation processes of migration and coarsening occurred by the followings mechanisms; (1) dissolution of Pt ; (2) diffusion of Pt ion ; (3) Pt ion chemical reduction in membrane; (4) Coarsening of Pt particles (Ostwald ripening) ; (5) polygon shape change of Pt by {111} plane growth.

• 한국정밀공학회지
• /
• 제22권4호
• /
• pp.52-59
• /
• 2005

When a micro hole is machined by EDM with a cylindrical electrode, the hole diameter is different at the inlet and the outlet of the micro hole. The taper shape of the micro hole is caused by not only wear of the electrode but the eroded particles. The eroded particles cause secondary discharge during machining the micro hole. As a result, the diameter of the inlet becomes larger than that of the outlet. In this paper, a new method is proposed to reduce the difference in diameter between the inlet and the outlet of the hole. Observed was that the feed depth and machining time affect the formation of taper shape On this experimental basis, ultrasonic vibration was applied to reduce machining time, and capacitance was changed during machining to use the difference in discharging energy of different capacitances. Using the proposed method, a straight micro-hole was fabricated.

• 한국정밀공학회지
• /
• 제20권1호
• /
• pp.43-49
• /
• 2003

In this study, micro electrochemical machining method was introduced for accomplishment the fabrication technology of functional parts and smart structures using the Ni-Ti shape memory alloy. From the experimental result, the micro part which has very fine surface could be achieved by use of micro electrochemical process with point electrode method. Concretely, the optimal performance of micro electrochemical process in Ni-Ti SMA was obtained at the condition of approximately 100% of current efficiency and high frequency pulse current. That is, much finer surface integrity and shape memory effect can be obtained at the same condition mentioned above.