• 오토저널
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• 제14권2호
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• pp.76-87
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• 1992

Flow and heat transfer characteristics in a horizontal electronic circuit board are studied numerically. The board has the arrays of heated blocks and the spaces between the plates and blocks are changed. Air in used as cooling fluid, of which prandt1 number is 0.7. The velocity distributions, temperature distributions, Nusselt numbers and dimensionless friction factors are obtained on the spaces between the plates and the blocks, for the cases of Rayleigh number, 0 and 10$^{5}$ . When Rayleigh number is so large, such as 10$^{5}$ , that the effect of bouyancy is not negligible, fluid friction and heat transfer is increased more than those of forced convection. This may be caused by the generation of secondary flow on the cross section of primary flow. The effect of bouyancy is of the most efficient, when the space of blocks is about block-width and the space of plates is about 1.7 times of block-height.

• 산업공학
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• 제12권1호
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• pp.56-67
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• 1999

This paper is about implementation issues for use of the Internet technology in education. An examination of the current status of virtual university provides guidance for subsequent prototype development. A virtual university is the Internet based process by which students increase their specific knowledge and skills via electronic interaction with content and people. Virtual university enables colleges and universities to provide students and faculty with network access to courseware and educational materials on multimedia servers free from time and geography constraints. In this paper, we present a prototype instruction support system (ISS). The ISS consists of the following components in architecture: Internet, software, hardware, database systems, users, and workflow. The ISS also assists several functions as follows: lecture notes, register processes, attendance checks, built-in boards, grading systems, questions and answers, electronic libraries, chats, and search engines. Our work will provide a guideline for the development of a virtual classroom for distance education and learning.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.663-666
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• 2000

Laser direct writing of micro-patterned copper lines has been achieved by pyrolytic decomposition of copper formate films (Cu(HCOO)$_2$$.$4H$_2$O), as a precursor, using a focused Ar$\^$+/ laser beam ($\lambda$= 514 nm) on PCB boards and glass substrates. The linewidth and thickness of the lines were investigated as a function of laser power and scan speed. The profiles of the lines were measured by scanning electron microscope (SEM), surface profiler (${\alpha}$-step) and atomic force microscopy (AFM). The electrical resistivities of the patterned lines were also investigated as a function of laser parameter using probe station and semiconductor analyzer. we compared resistivities of the patterned lines with that of the Cu bulk, respectively.

• 한국IT서비스학회지
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• 제12권4호
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• pp.449-459
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• 2013

The software which is used for electronic bulletin boards have shortcomings that the addition of new function and new information's type to the order point software is very difficult, and the aggressive adaption of newly introduced type of media is impossible because the software is developed by custom solution. Eventually new cost and time are required to enhance functionality or performance to software of DID(Digital Information Display). In this paper, we proposed the scheme to package DID's contents and to customize it using plug-in method. We conducted a case study of this scheme. The platform which can install Apps to DID as one of content was designed. Apps can be inserted by plug-in type on DID platform and run separately with DID framework. As a result, We got advantage that various contents, functions and Apps which are drived on Android can be displayed without any restriction and dependency because Apps itself is one of dynamic notice object. This solution increase reusability of Apps or contents, and can be used easily in various places such as airports, stations, terminals, and front desk by customizing.

• 한국전자통신학회논문지
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• 제11권5호
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• pp.465-472
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• 2016

본 논문에서는 PCB(: Printed Circuit Board) 패턴 검출을 위하여 Camera Link(Medium)을 지원하는 FPGA 기반 패턴 매칭 시스템을 구현하였다. 최근 생산되고 있는 PCB 패턴은 고집적화 시스템을 위해 점점 미세해지고 복잡해지고 있다. PCB 생산 공정의 비전 자동화를 위하여 고속 처리가 가능한 FPGA 기반 시스템을 제작하였고, 패턴 검출을 위해 사용되는 비전 라이브러리를 IP(: Intellectual property)로 구현하였다. 구현한 IP는 Camera Link IP, 패턴 매칭 IP, VGA IP, 에지 검출 IP, 메모리 IP이다.

• Journal of Power Electronics
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• 제12권5호
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• pp.813-820
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• 2012

This paper presents the development of a software supported acquisition system for metrological verification and testing of the equipment for monitoring and analysis of the basic electrical power quality parameters. The described procedure consists of two functionally connected segments. The first segment involves generation of the reference three-phase voltage signals, including the possibility of simulation of the various power quality disturbances, typical for electrical power distribution networks. The second part of this procedure includes the real-time recording of power quality disturbances in three-phase distribution networks. The procedure is functionally supported by the virtual instrumentation concept, including a software application developed in LabVIEW environment and data acquisition boards NI 6713 and NI 9215A. The software support of this system performs graphical presentation of the previously generated and recorded signal waveforms. A number of the control functions and buttons, implemented on the virtual instrument front panels, are provided to adjust the basic signal acquisition, generation and recording parameters.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.81-86
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• 2019

본 논문은 복수개의 스위칭모드 전원장치를 병렬 결선을 통하여 부하에 보다 큰 전력을 공급가능하게 하는 시스템 설계에 관한 것이다. 이를 위해 정전압조정기의 출력단에 션트저항을 직렬로 배치하고 아두이노를 이용하여 출력단 전압을 감지하고 제어하도록 하였다. 본 논문에서는 실험을 위해 두 개의 정전압조정기를 이용하였으나 그 이상의 보드에 대해서도 일반화가 가능할 것이다. 이와 같은 방식으로 제어되는 시스템을 통해 두 개의 시스템이 부하에 전달되는 전류의 합이 각각의 보드에서 나온 전류의 96%가 부하에 전달되는 것을 확인하였다. 효율의 경우 단위 보드에서의 효율은 92.4% 정도가 나왔으며 병렬결선 시에는 90% 정도가 나왔다.

• Corrosion Science and Technology
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• 제6권6호
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• pp.282-285
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• 2007

Smaller size and higher integration of electronic systems make narrower interconnect pitch not only in chip-level but also in package-level. Moreover electronic systems are required to operate in harsher conditions, that is, higher current / voltage, elevated temperature / humidity, and complex chemical contaminants. Under these severe circumstances, electronic components respond to applied voltages by electrochemically ionization of metals and conducting filament forms between anode and cathode across a nonmetallic medium. This phenomenon is called as the electrochemical migration. Many kinds of metal (Cu, Ag, SnPb, Sn etc) using in electronic packages are failed by ECM. Eutectic SnPb which is used in various electronic packaging structures, that is, printed circuit boards, plastic-encapsulated packages, organic display panels, and tape chip carriers, chip-on-films etc. And the material for soldering (eutectic SnPb) using in electronic package easily makes insulation failure by ECM. In real PCB system, not only metals but also many chemical species are included. And these chemical species act as resources of contamination. Model test systems were developed to characterize the migration phenomena without contamination effect. The serpentine-shape pattern was developed for analyzing relationship of applied voltage bias and failure lifetime by the temperature / humidity biased(THB) test.

• 대한전자공학회논문지SD
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• 제47권6호
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• pp.43-50
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• 2010

본 논문에서는 시스템 모듈에서 발생하는 EMI를 줄이기 위해 분할된 전원/접지 평판 구조에 의해 발생하는 방사성 방출(Radiated emission)을 분석하였다. 분석을 위해 다양한 조건을 갖는 시험 기판(Test board)에 대한 자기장과 전기장을 시뮬레이션하고 측정하여 비교하였다. 이 분석 결과는 입력 신호의 주파수 대역에서 반사계수의 위상이 $0^{\circ}$에 근접하도록 하며, 입력 신호의 주파수와 분할된 전원/접지 평판 구조의 공진주파수가 일치하지 않도록 분할된 접지 갭의 폭과 위치를 결정함으로써 방사성 방출을 줄일 수 있음을 보여준다. 또한, 스티칭 커패시터(Stitching capacitor)를 사용하여 방사성 방출을 저감시킬 수 있으며, 방사성 방출을 효과적으로 저감시키기 위해 입력 신호의 주파수에서 반사계수의 크기를 낮추고 위상이 $0^{\circ}$에 근접하도록 스티칭 커패시터의 값과 위치를 결정할 필요가 있음을 알 수 있다.

• 공업화학
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• 제23권4호
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• pp.367-371
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• 2012

폐 인쇄회로기판(WPCBs)은 Cu, Ni, Au, Ag, Pd 등의 희귀금속을 함유하고 있다. 폐 전자제품의 양이 지속적으로 증가하므로, WPCBs에서 희귀금속을 회수하는 방법에 대한 연구가 필요하다. WPCBs에서 유리섬유 보강 에폭시수지로부터 금속과 유리섬유 및 에폭시 수지로 원재료로 분리하는 방법으로 화학적 재활용 방법은 어려운 방법으로 알려져 있다. 본 연구에서는 WPCBs에서 금속 및 비금속성분을 분리하는 화학적 방법으로 에폭시 수지의 해중합을 methylpyrrolidone와 dimethylformamide 용매에서 $K_3PO_4$ 촉매를 사용하였다. WPCBs의 반응온도를 $160{\sim}200^{\circ}C$범위에서 진행하였고 반응시간을 2~12 h하여 반응을 진행하였다. WPCBs의 반응 후 얻은 재생 유리섬유를 열중량분석기를 통해 분석하였으며 WPCBs에서 에폭시 수지의 용해도를 조사하였다.