• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.49-53
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• 2011

High-speed Cu filling into a through-silicon-via (TSV) and simplification of bumping process by electroplating for three dimensional stacking of Si dice were investigated. The TSV was prepared on a Si wafer by deep reactive ion etching, and $SiO_2$, Ti and Au layers were coated as functional layers on the via wall. In order to increase the filling rate of Cu into the via, a periodic-pulse-reverse wave current was applied to the Si chip during electroplating. In the bumping process, Sn-3.5Ag bumping was performed on the Cu plugs without lithography process. After electroplating, the cross sections of the vias and appearance of the bumps were observed by using a field emission scanning electron microscope. As a result, voids in the Cu-plugs were produced by via blocking around via opening and at the middle of the via when the vias were plated for 60 min at -9.66 $mA/cm^2$ and -7.71 $mA/cm^2$, respectively. The Cu plug with a void or a defect led to the production of imperfect Sn-Ag bump which was formed on the Cu-plug.

• Polymer(Korea)
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• v.36 no.2
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• pp.229-234
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• 2012

This paper studied the effects of the content and the orientation of the disk shape fillers on the modulus of PP composites. The experimental results were compared with the theoretical calculations which included the three dimensional ellipsoids and analyzed by two aspect ratios, ${\rho}_{\alpha}=a_1/a_3$and ${\rho}_{\beta}=a_1/a_2$proposed by Lee and his researchers. Mica and talc were used as disk shape fillers in the composites. The shapes of mica and talc were observed by SEM and aspect ratios were statistically calculated. For the case of mica, the average aspect ratios were ${\rho}_{\alpha}=13.5$ and ${\rho}_{\beta}=1.8$, and for the case of talc, they were ${\rho}_{\alpha}=3.8$ and ${\rho}_{\beta}=1.4$. Also, the effects of two aspect ratios and the content of filler on the mechanical properties were studied: For 30 wt% of mica, $E_{11}$ increased up to about 2.7 times, and for the other case of talc, $E_{11}$ increased up to about 2.3 times, respectively.

• Polymer(Korea)
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• v.31 no.2
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• pp.160-167
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• 2007

This paper proposes a model for the solutions predicting the coefficient of thermal expansion of composites including fiber-like shaped$(a_1>a_2=a_3)$ and disk-like shaped$(a_1=a_2>a_3)$ inclusions like two dimensional geometries, which was analyzed by one axis and a single aspect ratio, $(\rho_\alpha=a_1/a_3)$. The analysis follows the procedure developed for elastic moduli by using the Lee and Paul's approach. The effects of the aspect ratio on the coefficient of thermal expansion of composites containing aligned isotropic inclusions are examined. This model should be limited to analyze the composites with unidirectionally aligned inclusions and with complete binding to each other of both matrix and inclusions having homogeneous properties. The longitudinal coefficients of thermal expansion $\alpha_{11}$ decrease and approach the coefficient of thermal expansion of filler, as the aspect ratios increase. However, the transverse coefficients of thermal expansion $\alpha_{33}$ increase or decrease with the aspect ratios.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.8
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• pp.343-352
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• 2017

IEC62541, known as OPC-UA, is a standard communication protocol for Smart Grid (SG) and Smart Factory application platform. It was accepted as an IEC standard (IEC62541) in 2011 by IEC TC57, and is extending range of application as collaborating with other standrads. The government's policies to popularize EVs ("Workplace Charging Challenge"), the number of Electric vehicle which try to be charging in the factory is expected to increase. In this situation, indiscreet and uncontrolled EV charging can lead to some problems, such as excess of the peak demand capacity. Therefore, EVs, which is charging in SFs, must be monitoring and controlling to avoid and reduce peak demand. However, the standards for EVs charging differ from the standards for SFs. In other words, to increase the ease of use for drivers, and reduce risk for enterprise, we have needs of study to develop the protocols or to provide interoperability, for EVs charging in SFs. This paper deals with a EV charging management platform installing in a smart factory. And this platform can be easily integrated as part of SF management software. The main goal of this paper is to implement EV management system based on IEC61851 and IEC62541.

• Information Systems Review
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• v.23 no.3
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• pp.177-200
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• 2021

Recently, the use of prepaid electronic payments such as electronic wallets, digital currency and prepaid points is gradually increasing. Prepaid electronic payments has the characteristic of being used after charging first. This study empirically investigated the factors affecting the intention to use online charging in order to help improve the service that require prepaid recharge by applying transformed TAM. Since there are not many previous studies for the intention to use online charging, we extract factors through preceding researches for electronic cash and mobile easy payment. Also we analyze the intention to use online charging for transportation card users, focusing on the moderating effects. As a result of the study, it was found that 'convenience', 'ubiquity', and 'self-efficacy' among the independent variables had a positive (+) effect on mediation variable 'perceived usefulness'. 'Perceived usefulness' was analyzed to have a significant influence on the dependent variable 'usage intention'. According to users' gender, internet usage time, internet shopping frequency, online charging frequency and transportation card usage type, the moderating effect was significant on 'perceived usefulness' and 'usage intention'. As an implication, it was suggested that service improvement and differentiated marketing are needed in direction of increasing the usefulness of services. Additional research directions were proposed for services such as e-wallets, prepaid points and digital currencies by adding other factors and moderate variables.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.213-216
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• 2008

2차원 전극의 RhB 분해 성능은 Pt(+)-Pt(-) > Pt(+)-Sus(-) > Sus(+)-Sus(-) 전극의 순으로 나타났다. 3차원 전극은 Pt-ACF-Pt 전극만 2차원 전극보다 초기 반응속도가 낮고 최종 RhB농도가 높은 것으로 나타났으나 다른 전극은 충전물 종류에 관계 없이 2차원 전극보다 초기 반응속도가 높은 것으로 나타났다. 음극의 종류에 관계없이 3차원 전극의 충전물에 따른 RhB 분해는 GAC > Nonwoven fabric fiber > ACF로 나타났다. GAC 충전량이 50 g 이상에서 RhB 분해속도는 거의 유사한 것으로 나타났으나 전력을 고려한 단위 W당 시간당 RhB 농도 감소를 나타내었다. 그림에서 보듯이 최적 GAC 충전량은 50 g로 사료되었다. 최적 전류는 2.5 A로 사료되었다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.507-508
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• 2015

본 논문은 독립형 마이크로그리드의 운용을 위한 에너지관리전략(Energy Management Strategy)을 제안한다. 제안한 에너지관리전략은 독립형 마이크로그리드의 안정적인 운영을 위하여 신재생에너지의 발전량과 전체 부하량을 비교한 뒤 에너지저장장치(ESS, Energy Storage System)의 충전 및 방전을 결정한다. 또한 에너지저장장치의 잔존용량(SOC, State of Charge)에 따라 과충전/과방전을 예방하기 위하여 부하 차단, 분산전원의 운전 방식 및 디젤발전기의 발전을 제어하는 형태로 구성된다. 가상의 독립형 마이크로그리드를 구성하고 시뮬레이션을 진행하여 에너지관리전략의 적용 시 성능을 검증한다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.40-43
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• 2011

전해 커패시터의 발열 메커니즘 및 소손 패턴 해석에서 최초의 출화는 1차측 전원으로 확인되었다. 전해 커패시터 외부의 방폭캡이 탄화되었고, 인접한 기판에도 탄화된 흔적을 확인되었으나 극성의 역사용, 과전압의 인가 및 금속한 충전 및 방전 등은 없었다. 전해 커패시터 내부를 X-ray 분석한 결과 전극 및 극판에는 이상이 없는 것으로 확인되었다. 부품 사양에 제시된 하한사양한계(LSL)는 144[${\mu}F$], 상한사양한계(USL)는 216[${\mu}F$]이며, 소손된 전해 커패시터의 공정능력분포(Cpk)가 1.21로 분석된 것으로 보아 공정 개선이 필요한 것으로 판단된다. 전해커패시터의 발열 메커니즘은 AC 과전압의 인가, 서지의 유입, 내부 온도의 상승, 기밀불량 등에 의해 지배되는 것을 알 수 있었다. 전해 커패시터를 설계할 때 고려사항은 적절한 전압의 인가, 정확한 등가직렬저항(ESR)의 연결, 급속한 충전 및 방전의 제어, 충분한 유전정접의 여유(margin) 확보 등이 중요한 요소이다.

• Journal of Hydrogen and New Energy
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• v.35 no.4
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• pp.451-459
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• 2024

This paper quantitatively analyzes the causes of ammonia-filled- cylinder rupture based on Tait equation and the safety guidelines, focusing on liquid expansion, internal temperature, and overfilling. When there exists a safety volume, i.e., gas-occupied volume within the ammonia cylinder, the internal pressure due to temperature rise corresponds to the vapor pressure at that temperature, with an approximate circumferential stress increase of 1.43 MPa/℃. In the absence of the safety volume, the internal pressure due to temperature rise matches the pressure of the compressed liquid ammonia at that temperature, and the resulting circumferential stress gradient in the cylinder shell is approximately 55.94 MPa/℃.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.31-42
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• 2017

Many studies have been performed to reduce electric consumption in railway systems. Due to its low conduction loss and high regenerative braking efficiency characteristics, the ESS powered railway system is chosen as a promising candidate for future railway systems. This paper introduces the ESS powered railway system and analyzes current power charge calculation methods that have been set up by KEPCO (Korea Electric Power Corporation). Based on the analysis, this paper proposes two different power charge reduction methods for the railway system. One is to smooth the peaks of traction energy consumption by supplying additional energy to the grid. The other is to save electric charge by reducing electric energy consumed by the railway during the energy peak time, 2 p.m.~5 p.m., which has highest 'Won/kWh' rates. To verify the effectiveness of the proposed method, the power charge of Seoul Metro Line 2 is recalculated using the method.