• Journal of electromagnetic engineering and science
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• v.6 no.1
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• pp.62-70
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• 2006

This paper presents a new power plane design method incorporating a single geometry derived from a unit cell of photonic bandgap(PBG) structure. This method yields constantly wide suppression of parallel plate resonances from 0.9 GHz to 4.2 GHz and is very efficient to eliminate PCB resonances in a specified frequency region to provide effective suppression of simultaneous switching noise(SSN). It is shown that with only two cells the propagation of unwanted high frequency signals is effectively suppressed, while it could provide continuous return signal path. The measured results agree very well with theoretically predicted ones, and confirm that proposed method is effective for reducing EMI, with measured near-field distribution. The proposed topology is suitable for design of high speed digital system.

• IE interfaces
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• v.8 no.3
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• pp.259-267
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• 1995

A printed circuit board auto-insertion line consists of several processes of identical machines and produces several different types of PCBs. Each board must be processed by at most one machine in each process. So, we call it a flexible flow line. The load balancing is the one of the most important issues in the FFL which has many sequential processes. Therefore we have represented the job route selection model to balance the load of inter-process in the PCB auto-insertion line, and validated it by simulation.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.1
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• pp.31-36
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• 2005

In this paper, a planar type bandpass filter in multilayered PCB is presented. The multilayered PCB structure has some advantages on fabricating microwave devices such as the size reduction and ability of tight coupling by folding or embedding. The proposed BPF has two transmission zeros at the both sides of the center frequency by using independent electric and magnetic coupling structure. The designed BPF with four layer teflon PCBs of dielectric constant 2.94 has dimensions of 24x20x1.524 in mm, center frequency of 2.47GHz and bandwidth of about l00MHz. A good agrement is achieved between the measured result and the simulated one. The influences of air gaps between the layers are also analyzed and presented.

• IE interfaces
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• v.13 no.2
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• pp.195-203
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• 2000

This paper considers the problem of sequencing printed circuit boards(PCBs) on an automatic surface mount device(SMD) placement machine in order to minimize total setup time. Since the total set of component feeders needed by all boards cannot be loaded simultaneously on the magazine, the setup must be made between two successive boards in the sequence. It is assumed that the setup time depends on the number of component feeders to be replaced in the magazine. An important characteristic is that each feeder occupies a different number of slots in the magazine. This problem is equivalent to travelling salesman problem(TSP) except that the distances between two cities, that is, the setup times between two boards, are not known in advance. So, TSP-based heuristics with new distance functions are presented and their performances are compared through various test problems. Computational results indicate that our heuristics outperform existing methods.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.37-40
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• 2005

폐 프린터의 발생량이 해마다 증가하고 있으며 이에 대한 재활용이 필요하다. 폐 프린터의 재활용에 있어서 다른 구성성분보다 기판의 처리가 문제가 된다. 본 연구는 폐 프린터의 기판을 재활용하는 데에 습식처리공정을 적용하기 위하여 먼저 전처리로 분쇄와 분리를 실시하였다. 기판을 1cm 이하로 분쇄한 다음 자력선별기를 이용하여 자성물질을 제거하고 비자성물질을 대상으로 4, 12, 40 mesh의 체를 이용하여 시료를 분리하였다. 전처리를 통하여 금속성분 특히 구리가 다량 함유된 12/40# 에 속한 시료를 대상으로 산에 의한 침출실험을 실시하였다. 실험 변수로는 산의 종류, 산 농도, 반응 온도, pulp density 등이었다.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.64-67
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• 2003

Halogenated aromatic hydrocarbons (HAHs) including TCDD and PCBs are known to cause neurotoxic effects in both man and animals such as cognitive impairment and motor dysfunctions. While theses chemicals may lead to neurodevelopmental and neurobehavioral deficit, structural activity relationship and molecular targets for these chemicals are not elucidated.(omitted)

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.26-35
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• 1998

This paper presents a visual inspection algorithm looking for solder joint defects of IC chips on PCBs (Printed Circuit Boards). In this algorithm, seven features are proposed in order to categorize the solder joints into four classes such as normal, insufficient, excess, and no solder, and optimal back-propagation network is determined by error evaluation which depend on the number of neurons in hidden and out-put layers and selection of the features. In the end, a good accuracy of classification performance, an optimal determination of network structure and the effectiveness of chosen seven features are examined by experiment using proposed inspection algorithm.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.617-618
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBs) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.619-624
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBS) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.199-204
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• 2021

Ultra-compact electric vehicles have narrow space for power conversion devices. This work presents schemes to achieve the high-power density of a low-voltage DC-DC converter (LDC): simplifying a converter structure by using sync-buck topology, applying a planar inductor using PCB winding, and applying a plate-type heat sink. The heat sink is placed between two PCBs, which increases the contact surface between the PCB and the heat-dissipating device. It enables the miniaturization of the converter to improve the conditions of heat radiation. The validity of the proposed scheme is verified through the experiment using a 500 W(12 V, 41.67 A) prototype with an input voltage range from 58 V to 84 V.