돌출부를 지닌 전극의 전기도금시스템에 대한 이론적 이차 전류분포 해석

손태원,주재백,Sohn, Tai-Won,Ju, Jeh-Beck 한국전기화학회 2009 한국전기화학회지 Vol.12 No.4

돌출부를 지니고 있는 전극의 전기도금 공정에 대한 이론적 이차 전류분포에 대하여 고찰하였다. 전극이 모두 전도체인 경우(Case 1)와 돌출부위만 전도체인 경우(Case 2) 두 가지 경우에 대하여 인가전위, 이온교환 전류밀도와 용액의 비전도도의 비인 $\xi$값, aspect ratio의 영향 등에 대하여 살펴보았다. 그 결과 인가 전위와 $\xi$값이 증가할수록 전류분포는 불균등화가 심화됨을 알 수 있었다. Aspect ratio가 작아질수록 전류분포가 보다 균등화되며 Case 2의 경우가 Case 1의 경우 보다 균등도가 좋아짐을 알 수 있었다. 돌출부위가 다양한 모양으로 이루진 전극에 대해서도 이 모델을 적용한 결과 전극 표면에 따른 국부 전류분포를 동시에 계산할 수 있음을 알 수 있었고 이 경우에도 이전과 마찬가지로 $\xi$값이 감소할수록 전류분포의 균등도가 좋아짐을 알 수 있었다. Theoretical calculations for the secondary current distributions for the electrode with a projection part in electroplating were performed. Two kinds of electrodes were considered. One is a electrode with the overall conducting surfaces(Case 1) and the other is an electrode in which only a projection part has a conducting surface(Case 2). The effects of applied potential, the ratio of ion exchange current to conductivity, $\xi$ and the aspect ratio on the current distribution were examined. The increase of applied current or the value of $\xi$ decreased the uniformity of current distribution. The small value of aspect ratio resulted the more uniform current distribution and Case 2 showed the better uniformity than Case 2. When this model was applied into an electrode with various projection parts, the local current distribution along the electrode surface were obtained successfully. In this case, the decrease of $\xi$ also increase the uniformity of current distribution as seen previously.

플라즈마 삽입전극의 전류에 미치는 밀도 구배의 영향

황휘동,구치욱,정경재,최재명,김곤호,고광철,Hwang, Hui-Dong,Gu, Chi-Wuk,Chung, Kyung-Jae,Choe, Jae-Myung,Kim, Gon-Ho,Ko, Kwang-Cheol 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.6

The conducting current of non-uniform plasma immersed electrode consists of ion current and secondary electron emission current caused by the impinging ion current. The ion current is determined by the ion dose passing through the sheath in front of electrode and the ion distribution in front of the electrode plays an important role in the secondary electron emission. The investigation of the distributed plasma and secondary electron effect on electrode ion current was carried out as the stainless steel electrode plugged with quartz tube was immersed in the inductively coupled Ar plasma using the antenna powered by 1 kw and the density profile was measured. After that, the negative voltage was applied by 1 kV~6 kV to measure the conduction current for the analysis of ion current.

Segmented cell approach for studying uniformity of current distribution in polymer electrolyte fuel cell operation

Kim, S.G.,Kim, M.J.,Sohn, Y.J. Pergamon Press ; Elsevier Science Ltd 2015 International journal of hydrogen energy Vol.40 No.35

In this study, the current distribution of a polymer electrolyte fuel cell (PEMFC) with a large active area is investigated using a segmented cell system. A specially designed printed circuit board (PCB)-type segmented cell is applied to a single-cell PEMFC. By using the segmented system, the effects of clamping pressure uniformity between the components of the PEMFC and the fuel injection direction are examined. The pressure uniformities of the two different types of endplates are measured using pressure indicating films (PIFs). A curved endplate is used to improve the pressure uniformity. The pressure uniformity is found to significantly influence the current distribution in a PEMFC with a large active area. Two types of gas feeding modes, parallel and cross injection, are tested. The results show that the clamping pressure uniformity and gas feeding configuration affect the current distribution and overall PEMFC performance.

단층원통형 고온초전도도체의 교류손실 특성

마용호,이주영,류경우,손송호,황시돌,Ma, Yong-Hu,Li, Zhu-Yong,Ryu, Kyung-Woo,Sohn, Song-Ho,Hwang, Si-Dol 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.7

The AC loss is an important issue in the design of the high temperature superconductor (HTS) power cables and fault current limiters. In these applications, a cylindrical HTS conductor is often used. In commercialization of these apparatuses, AC loss is a critical factor but not elucidated completely because of complexities in its measurement, e.g. non-uniform current distribution and phase difference between currents flowing in an individual HTS tape. We have prepared two cylindrical conductors composed of a Bi-2223 tape with different critical current density. In this paper, the AC loss characteristics of the conductors have been experimentally investigated and numerically analyzed. The result show that the measured losses for two conductors are not dependent on both arrangements and contact positions of a voltage lead. This implies that most of loss flux is only in the conductors. The loss for the Bi-2223 conductor with low critical current density is in good agreement with the calculated loss from Monoblock model, whereas the loss measured for the Bi-2223 conductor with high critical current density doesn't coincide with the loss calculated from the Monoblock model. The measured loss is also different from numerically calculated one based on the polygon model especially in low transport current.

Mulit Element를 이용한 PIFA 구조의 Intenna에 관한 연구

임요한,장기훈,윤영중,김용진,김영일,윤익재,Lim, Yo-Han,Chang, Ki-Hun,Yoon, Young-Joong,Kim, Yong-Jin,Kim, Young-Eil,Yoon, Ick-Jae 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.7

본 논문에서는 휴대폰용 내장형 PIFA 형태를 바탕으로 안테나 면을 4개의 element로 나눔으로써 넓은 대역폭과 향상된 이득 특성을 갖는 multi element 안테나를 제안하였으며, CDMA 대역인 $824{\sim}896MHz$와 RFID 대역인 $908.5{\sim}914MHz$를 동시에 만족하도록 설계하였다. 제안된 안테나의 크기는 $35{\times}15{\times}5mm^3$로 S사 A 모델의 케이스를 바탕으로 설계되었으며, 각 element를 안테나 안쪽으로 접어 넣음으로써 안테나의 소형화를 이루었다. 안테나의 광대역 및 향상된 이득 특성을 얻기 위해 안테나의 면을 4개의 element로 나누었다. 그 결과 전류의 패스가 길어지고 나뉘어짐에 따라, 안테나의 중심 주파수가 낮아지고 대역폭이 넓어지는 특성을 보였다. 또한, 안테나를 여러 개의 element로 나눔으로써 좀 더 고른 전류 분포를 갖게 되어 안테나의 효율이 향상되고 이득 값이 향상되는 특성을 가질 수 있었다. 좀 더 고른 전류 분포를 유도하여 안테나의 효율을 향상시키기 위해 전류가 각 element로 직접 전달되도록 급전 점에 변화를 주었다. 그 결과, 안테나의 이득 값이 더욱 향상되었으며, 급전 구조에 변화를 주면서 element를 4개로 설계하여 그 특성을 고찰한 결과, 가장 높은 이득 값을 보임을 확인하였다. 안테나의 이득 값을 유지한 상태로 소형화하기 위해 전류 방향을 고려하여 안테나의 각 element를 안테나의 앞면은 아래쪽으로 양 옆면은 안테나의 안쪽으로 접어 넣었다. 또한, 급전 위치를 조절하여 안테나의 공진 길이를 늘리기 위해 급전 점의 위치를 접지면의 윗부분에 배치하였다. 케이스를 고려하지 않은 상태로 원하는 안테나 특성을 얻었다고 하더라도, 케이스에 부착되면 주파수가 이동되고 원하는 주파수 대역에서 안테나 이득 값이 저하되기 때문에 휴대폰 케이스에 부착 시 $150{\sim}200MHz$의 주파수 이동이 발생함을 확인한 후에 1.08 GHz에 공진 주파수가 나타나도록 설계하였으며, 공진 주파수에서의 측정된 최대 이득 값은 3.1 dBi를 나타내었다. 케이스를 고려하여 측정한 경우, VSWR<2 기준 임피던스 대역폭은 $0.824{\sim}0.936GHz$로 110 MHz의 대역폭을 갖고 CDMA 대역과 RFID 대역을 동시에 만족할 수 있음을 나타내었다. 측정된 이득 값은 최소 -3.4 dBi에서 최대 -0.5 dBi를 나타내었고, 무지향성 패턴을 보임을 확인하였다. In this thesis, the Multi element antenna with wideband and enhanced gain characteristic is proposed to operate at both frequency range from 824 MHz to 896 11Hz for the CDMA and frequency range from 908.5 MHz to 914 MHz for the RFID band. The proposed antenna has tile size of $35{\times}15{\times}5mm^3$ in order to put it in the A model of S company and each element of the proposed antenna is folded to obtain the minimum size. To obtain the antenna with wideband and high gain characteristic, the radiator of the antenna is divided into 4 elements. As a result, bandwidth of the proposed antenna become broader and lower center frequency is appeared due to increased and lengthened current path. Moreover, the enhanced gain characteristic is verified because divided element structure that induct uniform current distribution can get increased antenna efficiency. To attain more uniform current distribution, modified structure of the feeding point that can deliver currents directly is designed. The antenna that alters the feeding structure has higher gain value. Each element is folded to increase the current paths considering the current directions to attain the miniaturization of the antenna. To measure the handset antenna, the handset case must be considered. Even though antenna is designed for predicted characteristic, the resonance frequency is shifted and antenna gain is deteriorated at predicted frequency while antenna is set in the handset case. 1.08 GHz of the resonant frequency is determined after frequency shift from 150 MHz to 200 MHz is confirmed and the maximum gain is measured as 3.1 dBi while antenna is not set in the handset. In case handset case is considered, the experimental results show that the impedance bandwidth for VSWR<2 is from 0.824 GHz to 0.936 GHz(110 MHz). This result appears that the proposed antenna can cover both CDMA and RFID band at once. The measured gain is from -3.4 dBi to -0.5 dBi and it has omni-directional pattern practically.

전착균일성에 미치는 보조음극의 영향

정순효,오영주 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.6

A numerical simulation based on the finite element method is used to investigate the effect of auxiliary electrode on the uniformity of deposition rate at a patterned electrode. The calculated deposition rates agreed well with the measured ones. Influences of the width of auxiliary electrode, gap between cathode and auxiliary electrode, distance between the inner wall of bath and auxiliary electrode and shape of auxiliary electrode on uniformity of electrodeposit have been studied. The optimum geometric factor of auxiliary electrode was obtained. (Received January 2, 2004)

Frequency Response Characteristics of a Grounding Grid

최종혁,이복희 한국조명.전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.5

The dissipation current distribution, potential rises and frequency-dependent impedances of the grounding grid were investigated. The computational simulations are made using the simplified EMTP-based model. Based on experimental and simulation results, the dissipation current at a frequency above ~100kHz intensively converged near the current injection point of the grounding grid, and decreased far from the current injection point. When the test current was injected at the center of the grounding grid, the high frequency grounding impedances were lower than those measured at the corner or side of the grounding grid. The trend of simulation results for the grounding impedance and dissipation current distribution calculated using a non-uniform distributed parameter circuit model are similar to the data measured at the test site.

Frequency Response Characteristics of a Grounding Grid

Jong-Hyuk Choi,Bok-Hee Lee 한국조명·전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.5

The dissipation current distribution, potential rises and frequency-dependent impedances of the grounding grid were investigated. The computational simulations are made using the simplified EMTP-based model. Based on experimental and simulation results, the dissipation current at a frequency above ~100㎑ intensively converged near the current injection point of the grounding grid, and decreased far from the current injection point. When the test current was injected at the center of the grounding grid, the high frequency grounding impedances were lower than those measured at the corner or side of the grounding grid. The trend of simulation results for the grounding impedance and dissipation current distribution calculated using a non-uniform distributed parameter circuit model are similar to the data measured at the test site.

Frequency Response Characteristics of a Grounding Grid

Choi, Jong-Hyuk,Lee, Bok-Hee The Korean Institute of IIIuminating and Electrica 2016 조명·전기설비학회논문지 Vol.30 No.5

The dissipation current distribution, potential rises and frequency-dependent impedances of the grounding grid were investigated. The computational simulations are made using the simplified EMTP-based model. Based on experimental and simulation results, the dissipation current at a frequency above ~100kHz intensively converged near the current injection point of the grounding grid, and decreased far from the current injection point. When the test current was injected at the center of the grounding grid, the high frequency grounding impedances were lower than those measured at the corner or side of the grounding grid. The trend of simulation results for the grounding impedance and dissipation current distribution calculated using a non-uniform distributed parameter circuit model are similar to the data measured at the test site.

왕복패들이 패턴화된 음극의 전착균일성에 미치는 영향

오영주,정순효,Oh Young-joo,Chung Soon-hyo 한국재료학회 2004 한국재료학회지 Vol.14 No.3

A numerical simulation based on the finite element method is used to investigate the effect of a reciprocal paddle on the uniformity of deposition rates at a patterned electrode. The calculated deposition rates agreed well with the measured values. The influences of the paddle velocity, the gap between cathodes and paddles, anode size and the distance between the anode and cathode have been studied. The optimum conditions on the paddle and geometric factors for electrodeposit uniformity could be obtained.