• Korean Chemical Engineering Research
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• 제53권6호
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• pp.792-797
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• 2015

그래핀은 다양하고 뛰어난 물성으로 그 적용 분야가 넓다. 그러나 반델반스 상호 작용으로 유기용매 내에서 쉽게 분산되지 않고 뭉쳐 있거나 포개진 상태로 존재한다. 게다가 그래핀은 화학적으로 비활성이며 크기나 모양이 넓은 분포도를 가지므로 균일한 상태 유지가 어렵다. 본 연구에서는 덩어리로 구성된 그래핀을 용매에 분산시키고 개질시키는 방법에 대해서 고찰하였다. 분산방법으로서 i) 유리비드를 이용한 물리적 분쇄. ii) 유리비드와 초음파를 이용한 처리 iii)유기용매에서의 분산 iv)드라이아이스를 이용한 개질법이 포함된다. 2.5 mm 크기의 유리비드처리는 대조구와 비교하여 36.4%의 감소율을 나타내었다. 유리비드(2.5 mm)와 초음파(225W, 10분) 병용 처리구가 76%로 입자 크기 감소효과를 나타내었다. 그래핀 입자 크기감소는 유리비드의 크기와 초음파 처리강도와 처리시간에 의존되었다. Ethyl acetate(EA)와 Isoprophyl alcohol(IPA)의 용매로 그래핀 표면을 개질시켰다. IPA용매에서 FT-IR 분석결과 CO 작용기가 높게 나타남으로 확인할 수 있었다. 한편, 드라이아이스로 그래핀 표면을 개질시킨 결과 처리 전 산소함량이 0.80%에서 처리 후 4.90%로 산소 함량 크게 증가되었다. 본 연구 결과로부터 IPA용매에 그래핀을 분산시킬 때 CO 작용기가 증가하여 장시간 분산상태 유지에 도움이 되는 것으로 판단된다.

• Journal of Welding and Joining
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• 제27권2호
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• pp.44-50
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• 2009

The characteristics of arc pressure, current density and heat flux distribution are important factors in understanding physical arc phenomena, which will have a marked effect on the penetration, size and shape of a weld in TIG welding. The purpose of this study is to find out the effect of the heat flux on the melting efficiency and penetration shape in TIG welding using the results of the previous investigators. The conclusions obtained permit to draw a proper method which derived the heat flux distributions by arc pressure distribution measurements, but previous researchers calculated heat flux and current distribution with the heat intensity measurements by the calorimetry. Heat flux of Ar gas arc was concentrated at the central part and distributed low from the arc axis to the radial direction, that of He mixing arc was lower than that of Ar gas, and it was wide distributed to radial direction. That showed a similar characteristic with the Nestor's by calorimetry calculated values. Throughout heat flux drawn in this study was discussed melting efficiency and penetration shape on Ar gas and He mixing gas arc.

• Asian-Australasian Journal of Animal Sciences
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• 제31권8호
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• pp.1127-1133
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• 2018

Objective: Genome wide association study was conducted to identify and validate candidate genes associated with fatty acid composition of pork. Methods: A total of 480 purebreed Duroc pigs were genotyped using IlluminaPorcine60k bead chips while the association test was implemented following genome-wide rapid association using Mixed Model and Regression-Genomic Control (GRAMMAR-GC) approach. Results: A total of 25, 29, and 16 single nucleotide polymorphisms (SNPs) were significantly associated with stearic (18:0), oleic (18:1) and saturated fatty acids (SFA), respectively. Genome wide significant variants were located on the same region of swine chromosome 14 (SSC14) that spanned from 120 to 124 Mb. Top SNP ALGA008191 was located at 5 kb near the stearoyl-CoA desaturase (SCD) gene. This gene is directly involved in desaturation of stearic acid into oleic acid. General relationship of significant SNPs showed high linkage disequilibrium thus genome-wide signals was attributed to SCD gene. However, understanding the role of other genes like elongation of very long chain fatty acids-3 (ELOVL3) located on this chromosomal segment might help in further understanding of metabolism and biosynthesis of fatty acids. Conclusion: Overall, this study provides evidence that validates SCD gene as strong candidate gene associated with fatty acid composition in Duroc pigs. Moreover, this study confirms significant SNPs near ELOVL3 gene.

• Asian Pacific Journal of Cancer Prevention
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• 제13권5호
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• pp.1917-1921
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• 2012

Background: Colorectal cancer is one of the leading causes of mortality worldwide. Genome wide analysis studies have identified sequence mutations causing loss-of-function that are associated with disease occurrence and severity. Epigenetic modifications, such DNA methylation, have also been implicated in many cancers but have yet to be examined in the East Asian population of colorectal cancer patients. Methods: Biopsies of tumors and matched non-cancerous tissue types were obtained and genomic DNA was isolated and subjected to the bisulphite conversion method for comparative DNA methylation analysis on the Illumina Infinium HumanMethylation27 BeadChip. Results: Totals of 258 and 74 genes were found to be hyper- and hypo-methylated as compared to the individual's matched control tissue. Interestingly, three genes that exhibited hypermethylation in their promoter regions, CMTM2, ECRG4, and SH3GL3, were shown to be significantly associated with colorectal cancer in previous studies. Using heatmap cluster analysis, eight hypermethylated and 10 hypomethylated genes were identified as significantly differentially methylated genes in the tumour tissues. Conclusions: Genome-wide methylation profiling facilitates rapid and simultaneous analysis of cancerous cells which may help to identify methylation markers with high sensitivity and specificity for diagnosis and prognosis. Our results show the promise of the microarray technology in identification of potential methylation biomarkers for colorectal cancers.

• Asian-Australasian Journal of Animal Sciences
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• 제32권5호
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• pp.607-613
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• 2019

Objective: Intramuscular fat (IMF) content plays an important role in meat quality. Identification of single nucleotide polymorphisms (SNPs) and genes related to pig IMF, especially using pig populations with high IMF content variation, can help to establish novel molecular breeding tools for optimizing IMF in pork and unveil the mechanisms that underlie fat metabolism. Methods: We collected muscle samples of 453 Chinese Lulai black pigs, measured IMF content by Soxhlet petroleum-ether extraction method, and genotyped genome-wide SNPs using GeneSeek Genomic Profiler Porcine HD BeadChip. Then a genome-wide association study was performed using a linear mixed model implemented in the GEMMA software. Results: A total of 43 SNPs were identified to be significantly associated with IMF content by the cutoff p<0.001. Among these significant SNPs, the greatest number of SNPs (n = 19) were detected on Chr.9, and two linkage disequilibrium blocks were formed among them. Additionally, 17 significant SNPs are mapped to previously reported quantitative trait loci (QTLs) of IMF and confirmed previous QTLs studies. Forty-two annotated genes centering these significant SNPs were obtained from Ensembl database. Overrepresentation test of pathways and gene ontology (GO) terms revealed some enriched reactome pathways and GO terms, which mainly involved regulation of basic material transport, energy metabolic process and signaling pathway. Conclusion: These findings improve our understanding of the genetic architecture of IMF content in pork and facilitate the follow-up study of fine-mapping genes that influence fat deposition in muscle.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1999년도 특별강연 및 추계학술발표대회 개요집
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• pp.43-46
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• 1999

It has been suggested that the motivation for automation of welding processes ncludes the replacement and extension of the functions of human operators. Among these types of the welding automation, SAW(Submerged Arc Welding) was prevalently used, because it is highly suited to a wide range of application, especially for the high speed welding. A Significant portion of the total manufacturing time for a pipe fabrication process is spent on the welding following primary machining and fit-up processes. To achieve the reliable weld bead appearance, the automatic seam tracking and adaptive control to fill the groove are urgently needed. This paper proposed the mechanical functions of multi-torches welding system, flux supply and recovery system in conjunction with the complex air pulsing method and various types of methodologies. It was shown that the multi-torches welding system revealed the high welding qualities for the circular and rectangular pipes. In conclusion, the multi-torches welding system developed will contribute the advanced welding technology, welding automation and increment of the market in these areas.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.181-189
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• 2001

For the Tailor Welded Blank sheet used fur automobile body panel, the characteristics of fatigue crack propagation behavior were studied. The thickness of specimen was machined to be same (0.9+0.9mm) and different (0.9+2.0mm). As a base test, mechanical properties around welding zone were examined. The results indicated that there were no significant decreases in mechanical properties, but hardness around welding bead is 2.3 times greater than base material. The crack propagation rate was noticeably decreased around welding line and rapidly increased as it passed by welding line. Reviewing the shape of the crack propagation, crack width around welding line was wide around the welding zone due to retardation of crack growth, but it became narrow passing welding line due to decreased toughness. Elasto-Plastic analysis was performed by finite element analysis fur explaining the test results.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 국제표면실장 및 인쇄회로기판 생산기자재전:전자패키지기술세미나
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• pp.1-19
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• 2003

The electronic market thrust for many hybrid circuit manufacturers is changing because commercial market segments such as telecommunications, automotive and consumer electronics have increased the demand world wide for environmentally friendly thick film products. This, in turn, places a stronger emphasis on the material suppliers within the circuit fabrication industry to provide toxin free products with equal or higher performance than traditional technology. A new group of silver based thick film conductors, which are totally free of such toxins as cadmium, nickel and Bead have been developed to meet new environmental requirements. Traditional thick film products and newly developed toxin free compositions will be compared and data will be presented. To evaluate their performance, both groups of conductors were tested for solder acceptance, leach resistance and aged adhesion with standard lead-containing solder and higher temperature lead-free solder.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.180-184
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• 2009

A novel set of experimental test tooling for measuring pulling and holding forces for drawbeads on binders inclined at a wide range of angles is introduced. A mechanical design featuring a single load cell, a male-female draw bead set, translation and rotation degrees of freedom, and a screw-driven clamping system has been incorporated into a standard tensile test machine. On a real time basis, restraining and holding force data with respect to draw-in displacement may be directly downloaded into a PC for data processing. The proposed experimental system represents a significant breakthrough in drawbead simulation technology due to its relatively low cost, clever design, and versatility. The system is shown to yield excellent experimental data suitable for verifying theory and numerical model predictions.

• Animal Bioscience
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• 제34권4호
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• pp.482-488
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• 2021

Objective: This study was conducted to estimate effect of single nucleotide polymorphisms (SNP) on the estimated breeding value of Hungarian Grey (HG) bulls and to find markers associated with horn colour. Methods: Genotypes 136 HG animals were determined on Geneseek high-density Bovine SNP 150K BeadChip. A multi-locus mixed-model was applied for statistical analyses. Results: Six SNPs were identified to be associated (-log10P>10) with green and white horn. These loci are located on chromosome 1, 3, 9, 18, and 25. Seven loci (on chromosome 1, 3, 6, 9, 10, 28) showed considerable association (-log10P>10) with the estimated breeding value. Conclusion: Analysis provides markers for further research of horn colour and supplies markers to achieve more effective selection work regarding estimated breeding value of HG.