• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1059-1061
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• 2005

The bushing currently applied to pole-mounted type loadbreak switch has porcelain bushing which is connected with the mold cone. This type has potential problems of uncertainty of sealing of the interface part and gas leakage on the connected part between bushing and switch tank due to the weight of the porcelain. The Composite Bushing can solve these problems and also the secondary problem of the potential accident owing to the fragment of the porcelain bushing in breakage due to the outer impact.

• 콘크리트학회논문집
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• 제27권2호
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• pp.157-167
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• 2015

고속 비상체에 의한 충격을 받는 시멘트 복합체는 표면관입, 배면박리 및 관통 등 국부적인 파괴거동을 보이며, 섬유혼입에 의한 휨인성의 향상으로 인해 배면파괴를 억제할 수 있다. 이에 섬유보강 시멘트 복합체의 내충격 성능에 관한 연구가 진행되고 있으며, 다양한 종류의 섬유보강재가 개발되고 있다. 섬유보강재의 종류에 따라 섬유와 매트릭스의 부착성능, 비표면적, 혼입개체수 등이 다르기 때문에 섬유보강 시멘트 복합체의 역학특성 및 고속 충격에 의한 내충격 성능의 향상에 미치는 효과에 대하여 검토할 필요가 있다. 본 연구에서는 성상 및 물성이 다른 강섬유(Steel fiber), 폴리아미드(Polyamide), 나일론(Nylon) 및 폴리에틸렌(Polyethylene)섬유를 혼입하여 섬유 종류에 따른 휨인성의 향상과 고속 비상체 충돌에 대한 파괴저감효과에 대하여 평가하였다. 그 결과, 혼입섬유의 가교작용에 의한 응력의 재분배 및 균열발생의 억제로 인해 휨인성이 향상되었으며, 고속충격에 의한 배면파괴를 억제할 수 있었다. 또한, 동일 충격에너지에서의 배면파괴한계두께를 감소시킬 수 있어 방호시설물에 적용할 경우 부재두께의 저감이 가능할 것으로 판단된다. 한편, 강섬유보강 시멘트복합체의 경우 배면박리가 발생하였으나, 섬유와 매트릭스의 부착에 의한 일부 파편의 박리가 억제되었으며, 합성섬유보강 시멘트복합체는 섬유의 혼입개체수가 많아, 고속충격에 의한 충격파의 상쇄작용 및 에너지 분산에 의한 미세균열이 발생해 배면파괴억제효과가 큰 것으로 판단된다.

• 농약과학회지
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• 제2권3호
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• pp.79-84
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• 1998

콩나물중 carbendazim 잔류분을 정량하고 확인할 수 있는 새로운 분석법을 확립하고자 tandem HPLC(UV & FL) 및 APcI를 source로 사용한 LC/MS를 이용하였다. 이를 위해 FL(fluorescence) 검출기를 UV(ultraviolet) 검출기와 나란히 연결하여 UV 검출기의 경우 280 nm 파장을 그리고 FL 검출기의 경우는 excitation파장과 emission파장을 각각 280 mn와 310 nm로 설정하였다. 분석결과 carbendazim의 검출한계는 $0.04{\mu}g/kg$이었다. 콩나물에 carbendazim을 0.5, 1.0 및 2.0 ppm 수준으로 첨가하여 회수율을 측정한 결과 그 평균값은 89.1%이었다. APcI source를 사용한 LC/MS 질량스펙트럼 방법은 콩나물중 carbendazim 잔류분을 최종 확인할 수 있었다. APcI LC/MS 방법은 전자충격에 의한 질량스펙트럼에 비해 훨씬 간단한 fragment를 형성할 뿐 만 아니라 carbendazim의 경우 m/z 133, m/z 159, m/z 191($M^{+}$)의 전형적인 fragment 이온을 형성하므로, 이 방법을 병행한다면 콩나물중 carbendazim 잔류분을 효과적으로 확인할 수 있을 것으로 사료되었다.

• 한국시뮬레이션학회논문지
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• 제29권1호
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• pp.1-9
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• 2020

과학기술의 발전에 따라 탄도탄에 대한 위협이 나날이 증대되고 있으며, 이러한 위협에 대처하기 위한 탄도탄 요격미사일에 대한 개발이 요구되고 있다. 대탄도탄용 요격미사일의 개발을 위해서는 요격시험이 필수적이다. 시험을 통해 얻은 계측자료를 활용하여 요격미사일을 포함한 전체적인 요격 시스템의 성능을 확인할 수 있다. 그러나 요격시험 시에는 요격에 의한 파편이 발생되기 때문에 안전을 위한 민간인의 접근 통제가 필요하다. 따라서 요격시험에 앞서 요격 파편에 대한 안전구역의 신뢰도 높은 추정이 선행되어야 한다. 본 논문에서는 모델링 분석 및 시뮬레이션을 활용하여 요격 파편에 대한 안전구역을 산출하였다. 우선, 탄도탄과 요격미사일의 발사단계에서 요격까지의 전 과정에 대한 시뮬레이션을 수행하였고, 요격 시점에서의 상대 속도 및 상대 각도를 산출하였다. 이 결과를 활용하여 요격 시의 에너지를 계산하고 요격 파편의 방출속도를 산출하였다. 이후, 파편에 작용하는 항력과 중력을 고려하여 낙하 궤적을 산출하였고, 파편의 낙하 지점과 위험도를 종합적으로 고려하여 최종 안전구역을 산출하였다.

• 패션비즈니스
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• 제15권2호
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• pp.145-159
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• 2011

The study aimed to analyze the status quo of manufacturing work environment and the work clothes' clothing comfort and wearer mobility of welding and grinding work processes in the machine and shipbuilding industries in South Korea. A questionnaire survey was conducted for the study, which consisted of questions about work clothes' clothing comfort and wearer mobility according to body parts. The findings derived from the research were: the high impact levels of work environment factors on welding and grinding work processes were noise, metal fragment, superheat, toxic gas, UV ray factors. Subject workers' assessment of work clothes' clothing pressures were in the levels between 3 (i.e. moderate) and 4 (i.e. comfortable) in a range of 5-point scale. The impact levels of wearer mobility factor were high on the work processes of welding and grinding in machine and grinding in shipbuilding. While welding process in shipbuilding showed a 'moderate' wearer mobility level and this was because its work postures were uncomfortable yet the rate of the motion change was low. The consideration to develop the work clothes specialized for certain work processes should include the materials' protecting performance from the hazardous work environment factors; and work clothes' designs that provides workers with maximized clothing comfort and wearer mobility for bending or tilting postures of upper, lower and lateral body parts defined in the study.

• Toxicological Research
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• 제29권2호
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• pp.107-114
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• 2013

Mass spectrometry (MS) is a very powerful instrument that can be used to analyze a wide range of materials such as proteins, peptides, DNA, drugs, and polymers. The process typically involves either chemical or electron (impact) ionization of the analyte. The resulting charged species or fragment is subsequently identified by the detector. Usually, single mass uses source-induced dissociation (SID), whereas mass/mass uses collision-induced dissociation (CID) to analyze the chemical fragmentations Each technique has its own advantages and disadvantages. While CID is most effective for the analysis of pure substances, multiple-step MS is a powerful technique to get structural data. Analysis of veterinary drugs ampicillin, chloramphenicol, ciprofloxacin, and oxytetracycline serves to highlight the slight differences between SID and CID. For example, minor differences were observed between ciprofloxacin and oxytetracycline via SID or CID. However, distinct fragmentation patterns were observed for ampicllin depending on the analysis method. Both SID and CID showed similar fragmentation spectra but different signal intensities for chloramphenicol. There are several factors that can influence the fragmentation spectra, such as the collision energy, major precursor ion, electrospray mode (positive or negative), and sample homogeneity. Therefore, one must select a fragmentation method on an empirical and case-by-case basis.

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.187-192
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• 2010

In order to monitor the possibility of horizontal gene transfer between transgenic rice and microorganisms in a paddy rice field, the gene flow from a bifunctional fusion (TPSP) rice containing trehalose-6-phosphate synthase and phosphatase to microorganisms in soils was investigated. The soil samples collected from the paddy rice field during June 2004 to March 2006 were investigated by multiplex PCR, Southern hybridization, and amplified fragment length polymorphism (AFLP). The TPSP gene from soil genomic DNAs was not detected by PCR. Soil genomic DNAs did not show homologies on the Southern blotting data, indicating that gene transfer did not occur during the last two years in the paddy rice field. In addition, the AFLP band patterns produced by soil genomic DNAs from both transgenic and non-transgenic rice fields appeared similar to each other when analyzed by the NTSYSpc program. Thus, these data suggest that transgenic rice does not give a significant impact on the communities of soil microorganisms, although long-term observation may be needed.

• Asian Pacific Journal of Cancer Prevention
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• 제13권6호
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• pp.2949-2953
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• 2012

The glutathione S transferase (GST) family is a major part of cellular defense mechanisms against endogenous and exogenous substances, many of which have carcinogenic potential. Alteration in the expression level or structure of the glutathione-S-transferase (GST) enzymes may lead to inadequate detoxification of potential carcinogens and consequently contribute to cancer development. A member of the glutathione-S-transferase (GST) family, GSTP1, is an attractive candidate for involvement in susceptibility to carcinogen-associated colorectal cancer. An $Ag{\rightarrow}G$ transition in exon 5 resulting in an Ile105Val amino acid substitution has been identified which alters catalytic efficiency. The present study investigated the possible impact of Ile105Val GSTP1 polymorphism on susceptibility to colorectal cancer. in Jordan We examined 90 tissue samples previously diagnosed with colorectal carcinoma, and 56 non-cancerous colon tissues. DNA was extracted from paraffin embedded tissues and the status of the GSTP1 polymorphism was determined using a polymerase chain reaction restriction fragment length polymorphism (RFLP) method. No statistically significant differences were found between colorectal cancer cases and controls for the GSTP1 Ile/Ile, Ile/Val and Val/Val genotypes. The glutathione S-transferase polymorphism was not associated with risk in colorectal cancer cases in Jordan stratified by age, sex, site, grade or tumor stage. In conclusion, the GSTP1 Ile105Val polymorphism is unlikely to affect the risk of colorectal cancer.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.493-498
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• 2002

Friction stir welding (FSW) is a relatively new solid-state joining process which can homogenize the heterogeneous microstructure by intensely plastic deformation arising from the rotation of the welding tool. The present study applied the FSW to an A356 aluminum (AI) alloy with the as-cast heterogeneous microstructure in the T6 temper condition, and examined an effect of microstructure on mechanical properties in the weld. The base material consisted of Al matrix with a high density of strengthening precipitates, large eutectic silicon and a lot of porosities. The FSW led to fragment of the eutectic silicon, extinction of the porosities and dissolution of the strengthening precipitates in the Al alloy. The dissolution of strengthening precipitates reduced the hardness of the weld around the weld center and the transverse ultimate tensile strength of the weld. Longitudinal tensile specimen containing only the stir zone showed the roughly same strength as the base material and a much larger elongation. Moreover, Charpy impact tests indicated that the stir zone had remarkably the higher absorbed energy than the base material. The higher mechanical properties of the stir zone were attributed to a homogenization of the as-cast heterogeneous microstructure by FSW.

• 분석과학
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• 제6권1호
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• pp.93-106
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• 1993

8종의 염소화유기인제 농약에 대한 전자충돌식으로 이온화시킨 질량분석법에 대하여 연구하였다. 대부분의 경우, 염소 원소를 포함하는 특성이온들은 그들의 동위원소에 기인하는 $^{37}Cl$ 피크에 의해 쉽게 확인되어진다. 즉 깨어진 이온의 염소 동위원소($^{37}Cl$)에 기인하는 피크량의 비를 측정함으로써 염소 원자수를 알 수 있다. 또한, 유기인제 부분은 과거에 보고되었던 질량분석 메카니즘과 비교하였을 때, 대체로 잘 일치함이 관측되었다.