• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1999년도 특별강연 및 추계학술발표대회 개요집
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• pp.310-313
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• 1999

This paper represents to develop a computer software system which is capable to analyze the phase transformation of high strength steel(BV-AH32) and to predict heat transfer, residual stress due to phase transformation during Gas Metal Arc(GMA) welding. The developed model was taken into account temperature dependent of young's modules, coefficient of thermal expansion and yield stress as well as the double ellipsoidal heat distribution by the moving arc. The results showed that the longitudinal and transverse residual stresses calculated by the coupled analysis of heat transfer, residual stress and phase transformation are in good agreement with the experimental data. In addition, the temperature distribution as well as longitudinal and transverse residual stresses of weldment were determined at the 1-pass and 2-pass of welding.

• Journal of Welding and Joining
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• 제21권5호
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• pp.547-554
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• 2003

Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive instrumented indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model. The residual stress from the indentation method was compared with that from the saw-cutting method.

• 소성∙가공
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• 제14권6호
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• pp.541-546
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• 2005

Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive continuous indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model. The residual stress from the indentation method was compared with that from the saw-cutting method.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.126-129
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• 2005

Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive continuous indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model. The residual stress from the indentation method was compared with that from the saw-cutting method.

• 분석과학
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• 제9권2호
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• pp.123-133
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• 1996

기체 크로마토그래피법을 이용하여 과수 재배용 살균제인 difenoconazole의 분석을 위한 최적 조건을 구하고, 사과와 토양 중에서의 잔류성을 조사하였다. 사과사료는 5% NaCl과 n-hexane액으로 분리, 농축하여 florisil column상에서 acetone과 n-hexane 혼합액으로 정제하여 GLC(ECD)로 분석하였다. 0.20과 1.0ppm의 표준물 첨가실험결과 평균회수율은 86.0~92.0% 였고, 검출한계는 0.01ppm 이었다. 사과에 대한 안정 사용기간은 수확 15일 전 3회 사용이 적당한 것으로 나타났으며, 이 경우 difenoconazole의 잔류량은 0.037ppm에서 0.044ppm 이었다. 토양시료를 methanol과 ammonium hydroxide 의 혼합액으로 추출하여 여과한 후 포화 NaCl 용액과 dichloromethane층으로 분배하였다. 유기층을 농축하여 toluene 용매로 재용해하였고, Sep-Pak column으로 정제한 후 GLC(FID)로 분석하였다. 0.10, 0.50과 1.0ppm 표준물 첨가실험 결과 평균 회수율은 101.2~103.7% 였고, 검출한계는 0.025ppm 이었다.

• 한국식품위생안전성학회지
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• 제8권1호
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• pp.9-15
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• 1993

어패류를 포함한 식용 육류중에 잔류하는 항생물질 및 항균성물질을 검출하기 위하여, 분석기기로서 Gas chromatography/ Mass spectrometry(GC/MS)를 사용한 동시분석법을 개발하였다. 여러 항생.항균제중에서 penicillin G, chloramphenicol, thiamphenicol을 중심으로 간단한 전처리과정과 유도체화를 하여 GC/MS 분석을 시행하였다. 전처리 과정을 요약하면 pH 4.0의 0.01 M EDTA-2Na McIlvaine buffer로의 추출, n-hexane으로의 탈지, Bond-Elute $C_{18}$ cartridge에 흡착된 물질의 0.01 M-methnolic oxalic acid로의 용출 그리고 건조 후 유도체화의 순으로 되어 있다. 본 방법에 의한 1 ppm spike시의 회수율은 penicillin G, chloramphenicol, thiamphenicol 각각 63.5%, 76.3%, 84.7%이었고, 검출한계는 각각 시료 g당 0.6, 0.085, $0.084\;\mu\textrm{g}$이었다. 또한 GC/MS 확인과정에서 실제 잔류농도가 1 ppm 이상이면 full scan spectrum으로 확인이 가능하였다. 이와 같은 GC/MS에 의한 잔류물질의 정량 및 확인시험은 앞의 미생물학적 방법의 복원은 물론 식품의 안전성 재고 및 규제독성의 측면에서도 매우 뜻 있는 연구라 하겠다.

• 한국재난정보학회 논문집
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• 제11권4호
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• pp.520-526
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• 2015

철근 콘크리트 구조에서 철근의 이음은 불가피하게 사용된다. 최근 들어 철근 콘크리트 구조물에 가장 많이 사용되고 있는 철근 이음에는 겹침 이음, 기계 이음, 그리고 용접 접합 등이 있다. 이중에서 저비용, 건설 현장에서의 실용성, 공사 기간 단축 및 고성능 등의 장점으로 인하여 가스 압접 이음의 효용성이 대두되고 있다. 그러나 가스 압접 이음 과정동안 철근이 열을 받게 되고 이는 접합부 주위에 잔류 응력으로 남아 철근의 피로수명에 영향을 미칠 수 있다. 그러므로 가스 압접 접합부의 명확한 잔류 응력 분석과 가스 압접 후 철근의 하중지지 능력을 확인하기 위한 인장 시험이 수행되어야 한다. 이 연구에서는 공용중인 철근(KS D3504 SD400)에 대하여 3차원 해석을 수행하여 연구 결과 잔류 응력은 상대적으로 작기 때문에 철근의 피로 수명에 영향을 미치지 않으며 인장 실험 결과에서도 가스 압접된 철근의 항복강도가 기준항복강도보다 높게 측정되어 하중 저항 능력도 가스 압접 이음부가 연속된 철근으로서의 거동에 충분히 그 성능을 발휘하는 것으로 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권3호
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• pp.406-413
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• 2014

A study was conducted to compare the effect of halal slaughter without stunning and gas stun killing followed by bleeding on residual blood content and storage stability of rabbit meat. Eighty male New Zealand white rabbits were divided into two groups of 40 animals each and subjected to either halal slaughter without stunning (HS) or gas stun-kill (GK). The volume of blood lost during exsanguination was measured. Residual blood was further quantified by determination of haemoglobin content in Longissimus lumborum (LL) muscle. Storage stability of the meat was evaluated by microbiological analysis and measuring lipid oxidation in terms of thiobarbituric acid reactive substances (TBARS). HS resulted in significantly higher blood loss than GK. HS had significantly lower residual haemoglobin in LL muscle compared to GK. Slaughter method had no effect on rabbit meat lipid oxidation at 0, 1, and 3 d postmortem. However, at 5 and 8 days of storage at $4^{\circ}C$, significant differences (p<0.05) were found, with meat from the GK group exhibiting significantly higher levels of MDA than that from HS. At day 3, greater growth of Pseudomonas aeroginosa and E. coli were observed in the GK group (p<0.05) with B. thermosphacta and total aerobic counts remained unaffected by slaughter method. At days 5 and 7 postmortem, bacterial counts for all tested microbes were affected by slaughter method, with GK exhibiting significantly higher growth than HS. It can be concluded that slaughter method can affect keeping quality of rabbit meat, and HS may be a favourable option compared to GK due to high bleed out.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
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• pp.87-89
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• 2000

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.145-148
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• 2006

Cold gas dynamic spray is a relatively new coating process by which coatings can be produced without significant heating during the process. Cold gas dynamic spray is conducted by powder sprayed by supersonic gas jet, and generally called the kinetic spray or cold-spray. Cold-spray was developed in Russia in the early 1980s to overcome the defect of thermal spray method. Its low process temperature can minimize thermal stress and also reduce the deformation of the substrate. Most researches on cold-spray have focused on micro scale coating, but our research team tried to apply this method to macro scale deposition. The macro scale deposition causes deformation of a thin substrate which is usually convex to the deposited side. In this research, the main cause of the deformation was investigated using 6061-T6 aluminum alloy and properties of deposited aluminum layer such as coefficient of thermal expansion, Elastic modulus, hardness, electric conductivity were measured. From the result of the analysis, it was concluded that compressive residual stress was the main reason of substrate deformation while CTE had little effect.