• 한국정밀공학회지
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• 제22권3호
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• pp.15-20
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• 2005

This paper describes the PCB drilling using an ultra high-speed air bearing spindle system and micro drill. For this research, we have developed the ultra high-speed air bearing spindle of 125,000 rpm and made an experiment for the application possibility in the PCB drilling. In order to estimate the drilling performance, we have investigated the size and damage of drilled hole, and the wear of drill at 90,000rpm. Results are as follows; we have confirmed the possibility in the PCB drilling of air bearing spindle. In case of micro-drilling PCB at $0.1mm\sim0.3mm$, the increase in the number of drilling has resulted in a bigger size of holes and also a bigger size of damage. It has been found that the wear of micro drill tends to concentrate in the main cutting edge.

• 한국전자파학회논문지
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• 제20권12호
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• pp.1272-1278
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• 2009

본 논문은 신호 전송용 비아가 있는 4층 PCB(Printed Circuit Boards)의 P/G(power/ground)면 사이에서 발생되는 공진을 상쇄시켜 복사성 방사(RE: Radiated Emission) 성능을 개선할 수 있는 기법을 제안하였다. 면간 공진 상쇄를 확인하기 위하여 비아가 있는 4층 PCB에서 신호 전송 선로의 전송 특성, PCB 개방 모서리를 통한 방사(radiation)와 RE 세기를 계산하고, 측정하여 제안된 기법의 타당성을 입증하였다.

• Journal of Microbiology and Biotechnology
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• 제13권4호
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• pp.495-500
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• 2003

Tight junctions (TJ) between adjacent Sertoli cells in testis are important for the formation of the blood testis barrier (BTB). In an effort to verify the reproductive health risk of endocrine-active chemicals (EACs), changes in the transepithelial electrical resistance (TER) and the expression of TJ genes were examined by co-planar polychlorinated biphenyl (PCB) treatment in cultured mouse Sertoli cells. Although the increase in TER of Sertoli cells was accelerated by 10 nM co-planar PCB, it was downregulated by 100 nM co-planar PCB. The expression of claudin-1 was downregulated by co-planar PCB in a concentration-dependent manner. On the contrary, the expression of claudin-1 was increased in the Sertoli cells by 10 nM co-planar PCB treatment. These results suggest that the structure and function of TJ may be targeted by co-planar PCB in Sertoli cells. Assessment of the structure and function of TJ in Sertoli cells might be useful for screening the reproductive health risk of EACs.

• 한국미생물·생명공학회지
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• 제22권4호
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• pp.353-359
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• 1994

Pseudomonas sp. P20 was a bacterial isolate which has the ability to degrade 4-chlorobi- phenyl(4CB) to 4-chlorobenzoic acid via the process of meta-cleavage. The recombinant plasmid pCK1 was constructed by insetting the 14-kb EcoRI fragment of the chromosomal DNA containing the 4CB-degrading genes into the vector pBluescript SK(+). Subsequently, E. coli XL1-Blue was transformed with the hybrid plasmid producing the recombinant E. coli CK1. The recombinant cells degraded 4CB and 2,3-dihydroxybiphenyl(2,3-DHBP) by the pcbAB and pcbCD gene products, respectively. The pcbC gene was expressed most abundantly at the late exponential phase in E. coli CK1 as well as in Pseudomonas sp. P20, and the level of the pcbC gene product, 2,3-DHBP dioxygenase, expressed in E. coli CK1 was about two-times higher than in Pseudomonas sp. P20. The activities of 2,3-DHBP dioxygenase on catechol and 3-methylcatechol were about 26 to 31% of its activity on 2,3-DHBP, but the enzyme did not reveal any activities on 4-methylcatechol and 4-chlorocatechol.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.3022-3024
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• 2005

연성 PCB(flexible printed circuit board)는 현재 노트북 PC와 디지털 카메라등에 적용되며, 굴곡성이 강하고 소형화 및 조립에 용이하여 주로 기판 사이나주기판과 외부 커넥터사이에 데이터의 전송매체로써 널리 사용되는 핵심부품이다. 근래에 개발되는 PCB 기반의 고성능 신호처리회로들은 데이터 전송율이 수백 MHz에서 수 GHz에 이르고 있으며, 신호선과 유전체, 접지판의 구조적 특성에 따라서, 반사 효과와 같은 신호무결성 문제들이 파생되어 신호의 최대성능을 제한하게된다. 이에 따라 적절한 임피던스 제어를 통하여 고성능신호들의 왜곡을 상쇄시키는 기술이 중요하게 되었다. 본 논문에서는 연성 PCB 전송라인을 위한 임피던스 모델을 대상으로 각 모델의 주요 특징 및 정확성을 분석하였다. 연성 PCB의 전송라인은 보통 전통적인 마이크로스트립 라인의 특성 임피던스 모델에 비해 신호선의 너비가 크며, 이를 반영한 개선된 수학적 임피던스 모델들이 제안되어 있다. 따라서 본 논문은 기존의 마이크로스트립 전송라인과 연성 PCB 전송라인에 적합한 수학적 모델들을 이용하여 신호 무결성 문제를 모의할 수 있는 CAE(computer-aided engineering) 도구의 임피던스 측정 결과를 비교 및 분석하였다.

• Environmental Analysis Health and Toxicology
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• 제22권3호
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• pp.279-285
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• 2007

The present study attempted to analyze the mechanism of PCB-induced neurotoxicity with respect to the PKC signaling. Since the developing neuron is particularly sensitive to PCB-induced neurotoxicity, we isolated cerebellar granule cells derived from 7-day old SD rats and grew cells in culture for additional 7 days to mimic PND-14 conditions. Only non-coplanar PCBs at a high dose showed a significant increase of total PKC activity at $[^3H]PDBu$ binding assay, indicating that non-coplanar PCBs are more neuroactive than coplanar PCBs in neuronal cells. PKC isoforms were immunoblotted with respective monoclonal antibodies. PKC-alpha and-epsilon were activated with non-coplanar PCB exposure. The result suggests that coplanar PCBs have a PKC pathway different from non-coplanar PCBs. Activation of PKC with exposure was dampened with treatment of high molecular weight of chitosan. Chilean (M.W. > 1,000 kDa) inhibited the total activity of PKC induced by the non-coplanar PCBs. Translocation of PKC isoforms was also inhibited by the high molecular weight of chitosan. The study demonstrated that non-coplanar PCBs are more potent neurotoxic congeners than coplanar PCBs and the alteration of PKC activities by PCB exposure can be blocked with the treatment of chitosan. The results suggest a potential use of chitosan as a means of nutritional intervention to prevent the harmful effects of pollutant-derived diseases.

• 한국위성정보통신학회논문지
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• 제9권4호
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• pp.42-46
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• 2014

본 논문에서는 1.55GHz에서 1.81GHz 대역을 사용하는 GNSS(Global-Navigation Satellite Service)시스템에, 단말기의 전원안정화를 위해서 PCB(Printed Circuit Board) 내층에 삽입될 코일 구조의 EBG(Electromagnetic Band Gap) 구조체를 제안 및 제작한다. 제작한 EBG 구조체의 테스트 결과, 사용 주파수 대역에서 삽입손실(S21)이 약 -50dB 이하로 측정되었다. 본 연구결과는 향후, PCB 회로 설계의 PDN(Power Delivery Network)구조의 안정화 향상 및 EMI(Electro Magnetic Interference) 대책에 효과적일 것으로 기대된다.

• Transactions on Electrical and Electronic Materials
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• 제9권5호
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• pp.206-208
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• 2008

Implantation of metals and ceramics with ions of nitrogen and other species has improved surface properties such as friction, wear and corrosion in numerous industrial applications. In recent years, PCB drills tend to be more minimized increasingly as the electronics components have been more highly accumulated and minimized. Therefore nitrogen ion implantation was performed onto PCB drill (0.15 & 0.3 mm in diameter), in order to investigate mechanical properties of WC-Co cermets surface through Nano-indentation tests. PCB drill was implanted at energy of 70 keV, 90 keV, 120 keV and with the dose range of $1{\times}10^{17}$ and $5{\times}10^{17}\;ions/cm^{2}$. After ion implantation, WC-Co PCB drill bits was tested in actual operating situation to apply cutting tools industry and is concluded that the life time of nitrogen ion implanted PCB drills is one and a half times longer than the unimplanted.

• 한국전기전자재료학회논문지
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• 제24권3호
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• pp.234-239
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• 2011

In this study, the heat transfer capability have been improved by using via-holes in FR4 PCB, when the LED lighting is designed to solve the thermal problem. The thermal resistance and junction temperature were measured by changing the dimension of FR4 PCB and size of via hole. As a result, when the dimension was increased initially, the thermal resistance and junction temperature was decreased rapidly, the ones was stabilized after the dimension of 200 $[mm^2]$. Also, the light output was improved up to maximum 17% by formation of via-hole and expansion of dimension in FR4 PCB. Therefore, the thermal resistance and junction temperature could be improved by expansion of PCB dimension and configuration of via-hole ability.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.296.2-296.2
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• 2002

Our previous study demonstrated that 2.3', 4.4'. 5- Pentachlorobiphenyl (PCB 118) showed an antiestrogenic activity in vitro and in vivo. In the present study. we examined the effect of PCB 118 on postnatal reproductive development in female rats. PCB 118 (0.001. 0.01 or 0.1 mg/kg/day) was administered to pregnant female SD rats from gestation day (GO) 6 to 18 via subcutaneous injection. and developmental parameters such as vaginal opening were determined. PCB 118 significantly delayed vaginal opening of female offsprings at dose of 0.1 ${\mu}g$/kg/day. whereas had no effects on body weights. In addition. in utero treatment of PCB 118 caused significant decreases in serum levels of E2, T3 and T4 in female oftsprings at certain doses on postnatal day (PND) 22. Our data of results indicate that in utero exposure to PCB 118 may postnatal reproductive development in female rat through its antiestrogenic activity.