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AZ31와 AZ61 마그네슘 합금의 이종 마찰교반용접 특성
박경도(Kyoung Do Park),이해진(Hae Jin Lee),이대열(Dai Yeol Lee),강대민(Dae Min Kang) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.5
Friction stir welding is a solid-state joining process and is useful for joining dissimilar metal sheets. In this study, the experimental conditions of the friction stir welding were determined by the two-way factorial design to evaluate the characteristics of the dissimilar friction stir welding of AZ31 and AZ61 magnesium alloys. The levels of rotation speed and welding speed, which are welding variables, were 1000, 2000, 3000 rpm and 100, 200, 300 mm/min, respectively. From the results, the greater the rotation speed and the lower the welding speed of the tool were, the greater the tensile strength of the welded part was. The contribution of the welding speed of the tool is larger than that of the rotation speed of the tool. In addition, the optimal conditions for tensile strength in the dissimilar friction stir joint were predicted to be the rotation speed of 3000 rpm and welding speed of 100 mm/min, and the tensile strength under the optimal conditions was estimated to be 214 ± 6.57 Mpa with 99% reliability.
머시닝센터를 활용한 알루미늄합금의 마찰교반용접 특성 분석
승영춘,박경도,이춘규,Seung, Young-Chun,Park, Kyoung-Do,Lee, Chun-Kyu 한국금형공학회 2020 한국금형공학회지 Vol.14 No.4
The purpose of this study was to analyze the change in tensile strength characteristics of the weld when the welding speed and rotational speed of the tool, which are representative variables of the friction stir welding process. The equipment used in the experiment was Machining Center No. 5. The material used in the experiment is an AA6061-T6 alloy, and a rolled plate with a thickness of 2mm was used. Two experimental variables were selected, the welding speed of the tool and the rotational speed of the tool. The experimental conditions were selected in the range in which a healthy weld could be obtained through a preliminary experiment. The welding speed of the tool was increased to 100mm/min, 200mm/min, and 300mm/min, and the rotational speed of the tool was increased to 1000rpm, 2000rpm, and 3000rpm. As a result of the experiment, the tensile strength increased as the rotational speed of the tool changed at each tool welding speed. In addition, as the welding speed of the tool increased, the tensile strength of the weld was increased. The condition with the highest tensile strength of the weld was found to be a tool feed speed of 300 mm/min and a tool rotation speed of 3000rpm.
단일염기다형성 정보를 이용한 국내 홀스타인 젖소의 유효집단 크기 추정
조광현,도경탁,박경도,Cho, Kwang-Hyun,Do, Kyoung-Tag,Park, Kyung-Do 한국데이터정보과학회 2017 한국데이터정보과학회지 Vol.28 No.3
본 연구는 홀스타인 젖소, 923두에 대한 단일염기다형성 (SNP) 42,201개를 이용하여 국내 젖소집단의 유전적 특성 및 유효집단크기를 조사하고자 실시하였다. 염색체별 인접 단일염기다형성간의 평균 연관불평형 ($r^2$)은 0.22로 추정되었으며, 14번 염색체 (0.26)에서 가장 높은 반면, 27번 염색체 (0.17)에서 가장 낮게 나타났다. SNP간의 물리적 거리가 25Kb 미만인 경우에서 $r^2$은 $0.31{\pm}0.33$으로 추정되었으며, SNP간 물리적 거리가 증가할수록 $r^2$은 현저히 감소하였다. SNP간 물리적 거리가 2.5Mb 이상에서의 $r^2$은 0.04로 25Kb 미만인 경우와 비교할 때 0.27 (87.1%) 감소하였다. 국내 홀스타인 젖소의 유효집단크기는 세대수와 비례하여 감소하는 경향을 나타내었으며, 1~5세대에서 110두로 추정되었다. In this study, we investigated the genetic characteristics and the effective population size of domestic dairy cattle using 42,201 SNPs for 923 heads of Holstein cattle. The estimate for the average linkage disequilibrium ($r^2$) among the adjacent SNPs by chromosome was 0.22, and it was highest (0.26) in chromosome 14 and lowest (0.17) in chromosome 27. When the physical distance among SNPs was less than 25Kb, the estimate for the average $r^2$ was $0.31{\pm}0.33$ and it was markedly decreased as the physical distance increased. When the physical distance among SNPs was larger than 25Mb, the estimate for the average $r^2$ was 0.04, and it decreased by 0.27 (87.1%) compared with case of physical distance of less than 25Kb. There was a trend that the effective population size in Holstein dairy cattle decreased over generations and the estimate for the effective population size in the first 5 generations (1~5th generation) was 110 heads.
실험계획법에 의한 AZ31 마그네슘 합금의 마찰교반용접 특성에 관한 연구
강대민(Dae Min Kang),박경도(Kyoung Do Park),정영석(Yung Suk Jung) 한국자동차공학회 2013 한국 자동차공학회논문집 Vol.21 No.4
In this paper, the design of experiment with two-way factorial design was adopted and from that, optimum values of welding variables including the welding speed and rotation speed were found to improve the strength of AZ31 magnesium alloy sheets joined by the friction stir technique. Tool with shoulder diameter of 12 mm and pin diameter of 3.5 mm was used. Also the welding direction was aligned with the material rolling direction, and dimensions of the AZ31 magnesium alloy sheets were 100×100×2 mm. Conditions of rotation speed were 1000, 1100 and 1200 rpm and those of welding speed were 200, 300 and 400 mm/min. As far as this work is concerned, the optimal conditions for friction stir joint were predicted as the rotation speed of 1200 rpm and welding speed of 200 mm/min.
오운용,도경탁,조병욱,박경도,김성훈,이학교,신영수,조영석,Oh, Woon-Yong,Do, Kyoung-Tag,Cho, Byung-Wook,Park, Kyung-Do,Kim, Sung-Hoon,Lee, Hak-Kyo,Shin, Young-Soo,Cho, Young-Seuk 한국데이터정보과학회 2011 한국데이터정보과학회지 Vol.22 No.3
'말산업육성법' 제정에 따라 국내 승마산업의 저변확대를 위해 자질이 우수한 국내산 승용마 생산 및 개량에 대한 연구가 절실히 필요한 실정이다. 따라서 본 논문에서는 국내에서 승용마로 활용되고 있는 3품종 (웜블러드, 더러브렛, 제주산마) 32두에 대해 12항목의 체형을 측정하여, 측정자료를 바탕으로 판별분석을 실시한 결과 81.3%가 정확하게 분류되는 것을 확인 할 수 있었다. 본 연구의 결과는 향후 체구성 분석을 통한 말의 유형 (경주마, 승용마, 재활치료마, 역용마, 비육마) 및 승용마 외모 심사를 판단하는 모형 개발에 기초자료로 활용될 것이며 이는 향후 3D 영상촬영측정치를 활용한 한국형 승용마 생산 및 개량화 연구에 활용될 것으로 사료된다. There are increasing demands for the producing and breeding new domestic riding horses for the vitalizations of horse riding industry in Korea, according as 'Horse Industry Support Act' became. In this study, we were to develop the functional relation through the conformation comparison & body composition analysis. 76 heads of 5 breeds utilized for riding horses in Korea were used and their body measurements on 12 items were measured and cluster analysis was conducted to determine the correlation relation among them. The measurements were standardized that (height, croup height, pelvis length), and (hip width, width of pelvis) were highly correlated. In these results of the decision tree, we confirmed to classify the breed type determination by their body measurements (hip height, hip width, head length, croup height). This result can be used as basic data for the development of horse type determination (racing, riding, Riding for the Disabled, Working, or fattening) through the analysis of body composition, and be utilized as the basic data for the producing and breeding new domestic riding horses through the 3D Stereosocpic image system analyze.
직교배열법에 의한 AZ31 마그네슘 합금의 마찰교반접합 특성
강대민(Dae-Min Kang),박경도(Kyoung-Do Park),강정윤(Chung-Yun Kang) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.6
Magnesium alloy has been focussed as lightweight material owing to its high strength even though low density with aluminum alloy, titanium alloy and plastic material. Friction stir welding technique was performed by rotating and plunging a shouldered tool with a small diameter pin into the joint line between two butted plates and useful to join magnesium alloy. In this paper, the experiments of friction stir welding were done to investigate the joint characteristics of AZ31 magnesium alloy. For its evaluation, the orthogonal array method(L27(313)) was applied with four factors of pin diameter, shoulder diameter, travel speed and rotation speed of tool and also three levels of each factor. Nine tools were worked through shoulder diameter of 9, 12, 15mm and pin root diameter of 3, 4, 5mm. In addition tensile tests were excuted for the assessment of mechanical properties for joint conditions. From the results, pin diameter, shoulder diameter, and rotating speed of tool influenced on the tensile strength meaningful, but welding speed did not influence on that by the variance analysis. Beside of that, optimum condition of tensile strength was estimated as following ; shoulder diameter:15mm, welding speed:200mm/min, rotating speed:200rpm