플럭스 코어드 와이어에 따른 용접 중 콘택트 팁 내마모성 평가

김동윤,황인성,김동철,강문진,Kim, Dong-Yoon,Hwang, In-Sung,Kim, Dong-Cheol,Kang, Moon-Jin 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.4

The contact tip for flux cored arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. A damaged contact tip causes a productivity reduction and a welding quality problem. In this study, the welding experiments for the wear resistance of contact tip regarding flux cored wire types were performed. With two fold type and a seamless type flux cored wires, the wear rates of contact tips were compared. In addition, the wear rate was checked according to the contact tip position.

마이토마이신을 이용한 라섹 수술 후 지연성으로 발생한 비대 각막 반흔 2예

김동윤,김명준,윤삼영,신철진,김경훈,차흥원,Dong Yoon Kim,MD,Myoung Joon Kim,MD,PhD,Sam Young Yoon,MD,Chul Jin Shin,MD,Kyoung Hoon Kim,MD,Hungwon Tchah,MD,PhD 대한안과학회 2009 대한안과학회지 Vol.50 No.2

Purpose: To report late-onset hypertrophic corneal scars after laser epithelial keratomileusis (LASEK) with mitomycin C. Case summary: Case 1. A 34-year-old man who had undergone LASEK with mitomycin C 15 months prior was referred to our clinic because of corneal opacity of his right eye. After LASEK, there have been no abnormalities in either of his eyes. However, 11 monthsafter LASEK, he experienced decreased visual acuity in his right eye. The visual acuity was 0.03 in his right eye and 1.0 in his left eye. On slit lamp examination there was a whitish, hypertrophic scarin his right cornea. The lesion was located in the corneal center and the subepithelial space. Central corneal thickness was 828 μm. Case 2. A 23-year-old woman who had undergone LASEK with mitomycin C 14 months before was referred our clinic because of corneal opacity of her left eye. After LASEK, there had been no abnormalities in either of her eyes. However, 12 months after LASEK she experienced decreased visual acuity in her left eye. The visual acuity was 1.0 in her right eye and 0.2 in her left eye. On slit lamp examination there was a whitish, hypertrophic scar in her left cornea. Central corneal thickness was 794 μm. Conclusions: Manual debridement was performed to remove the hypertrophic scar in both cases. Case 1. After manual debridement, visual acuity of the right eye improved to 0.63. Case 2. After manual debridement, best-corrected visual acuity of the left eye was 0.63.

부분결합간섭계에 내장된 인공수정체 도수측정 공식들의 정확성 비교

김동윤,김명준,김재용,차흥원,Dong Yoon Kim,MD,Myoung Joon Kim,MD,PhD,Jae Yong Kim,MD,PhD,Hungwon Tchah,MD,PhD 대한안과학회 2009 대한안과학회지 Vol.50 No.4

Purpose: To evaluate the accuracy of various formulas installed in IOLMaster software which uses partial coherence interferometry for axial length measurement. Methods: This retrospective comparative study included 81 eyes of consecutive patients who had uneventful cataract surgery with implantation of Acrysof single piece (SA60AT) IOL. Axial length was measured with IOLMaster and IOL power was calculated using various formulas, including SRK II, SRK/T, Holladay 1, Haigis, and Hoffer Q. Subjects were stratified by axial length into Groups A (axial length < 23.50 mm), B (23.50 mm ≤ axial length < 25.00 mm), and C (axial length ≥ 25.00 mm). Target refractions of the five formulas were compared to the postoperative manifest refraction at 1 month. Results: The five formulas showed no difference in predicting postoperative refractive errors among all of the groups. Conclusions: Five formulas installed in IOLMaster software provided equivalent predictions of postoperative refractive error regardless of axial length. J Korean Ophthalmol Soc 2009;50(4):523-528

시편 예열 온도가 FCW 용착금속의 확산성 수소량에 미치는 영향

김동윤,황인성,김동철,강문진,Kim, Dong Yoon,Hwang, In Sung,Kim, Dong Cheol,Kang, Moon Jin 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.2

Cold cracking of weldment is one of the most serious welding problems. A sufficient quantity of diffusible hydrogen, a residual stress, and a sensitive microstructure are the causes of cold cracking. Removal of any one of these factors can be used to prevent cold cracking. Application of flux cored arc welding process is increasing due to high productivity and easiness of welding. In addition, to prevent cold cracking in the HAZ or weldment, preheat temperature and interpass temperature have to be controlled. In this study, the effect of preheat temperature on the levels of diffusible hydrogen in the weld metal deposited using flux cored wire was examined. The levels of preheat temperature of base metal specimen were ambient temperature, 50, 100 and $150^{\circ}C$ respectively. The result showed that the increase of preheat temperature was a linear relationship with reduction of diffusible hydrogen content in weldment.

GMA용접에서 콘택트 팁 재질에 따른 용접특성 평가

김동윤,황인성,김동철,강문진,Kim, Dong Yoon,Hwang, In Sung,Kim, Dong Cheol,Kang, Moon Jin 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.6

The contact tip for gas metal arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. If the contact tip is damaged, it is a cause of lowering the welding productivity due to removal of welding defects and replacement of contact tip. In case of the use of a contact tip for a long time the arc is unstable because the processed hole in the contact tip center is larger, and the variation of aiming position of the welding wire causes a seam tracking error. In this study, gas metal arc welding experiments using contact tip of three different materials were performed. The contact tips with Cu-P, Cu-Cr, and Cu-ODS were used at the experiments, and the welding characteristics by each contact tip were evaluated. After welding contact tip appearance, welding spatter adhesion amount of the nozzle, and weld bead appearance were evaluated. The welding current and welding voltage were measured to verify arc stability during arc welding.

마을 만들기 연구의 정량적 접근에 관한 소고 - 마을 만들기 사업규모와 성과의 관계를 중심으로 -

김동윤,김선직,강래천,Kim, Dong-Yoon,Kim, Sun-Jick,Kang, Rae-Cheon 한국디지털건축·인테리어학회 2011 한국디지털건축인테리어학회 논문집 Vol.11 No.2

Skeptical responses to urban design based on the Physical Planning theory assuming the existence of social agreement and the absolute authorities of planners bring about alternatives such as Participatory Planning and Community Design derived from Harbermas' Communicative Rationality. But the normative contentions do not progress any more to the stage of presenting practical strategies. This is the cause why there should be systematic approaches to reveal the relationships among various concepts or variables. With regard to the Community Design this study intends to take a statistical approach to find relationship between project scale and its accomplishment. The hypothesis that the smaller scale of project begets the better outcomes was tested to be rejected as a result of the analysis of variance. But the result also shows that appropriate density in relatively large area makes residents' expected satisfaction high. Although this discovery has its own meaning the tryout is anticipated to laying the cornerstone of quantitative analyses in the following studies.

원격 스캐너를 이용한 알루미늄 레이저 용접에 대한 생산 공정 최적화 설계

김동윤,박영환,Kim, Dong-Yoon,Park, Young-Whan 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.6

In this study, we conducted laser welding by using remote scanner that is 5J32 aluminum alloy to observe the mechanical properties and optimize welding process parameters. As the control factors, laser incident angle, laser power and welding speed were set and as the result of weldablility, tensile shear tests were performed. ANOVA (Analysis of Variation) was also carried out to identify the influence of process variables on tensile shear strength. Strength estimation models were suggested using regression alnalysis and 2nd order polynomial model had the best estimation performance. In addition optimal welding condition was determined in terms with wedalility and productivity using objective function and fitness function. Final optimized welding condition was laser power was 4 kW, and welding speed was 4.6 m/min.

저주파수 진동에서 딥러닝을 이용한 골절 판단 시스템

김동윤(Dong-Yoon Kim),윤길호(Gil-Ho Yoon),우연준(Yeon-Jun Woo),심성규(Seong-Gyu Sim),황세진(Sea-Jin Hwang) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

딥러닝 알고리즘을 이용한 새로운 비선형 변환 방법의 고장 진단 시스템

김동윤(Dong-Yoon Kim),우연준(Yeon-Jun Woo),윤길호(Gil Ho Yoon) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

온라인 커뮤니티는 토론 난제(難題)에서도 대안적인가?:

김동윤(Dong Yoon Kim),최종환(Jong Hwan Choi) 청운대학교 방송예술연구소 2014 미디어와 공연예술연구 Vol.9 No.3

온라인 커뮤니티의 대안적 미디어로서의 가능성은 온라인이라는 플랫폼이 가진 개방성과 자율성과 같은 매체기술적 요인 이외에도 다양한 커뮤니케이션 요소로부터 적지 않은 영향을 받는다. 이러한 다양한 요소들 가운데, 이 연구는 토론 주제가 가지는 속성이 온라인 커뮤니티의 대안성 발휘에 상당한 영향을 미칠 수 있다고 보고, ‘개성공단 사태’라는 정보 접근의 제약이 크고, 대안적 의견과 주장의 다양성을 확보하기 어려운 이른바 토론 난제에 대한 온라인 토론에서도 대안성이 발휘될 수 있는지를 검토해 보았다. 이를위해, 연구는 ‘개성공단 사태’에 대한 온라인 커뮤니티(<다음 아고라>)가 종이신문의 보도 양상(양적 내용분석)과 프레임(질적 내용분석)에 견주어 어떠한 구성적 다양성과 내용적 차별성을 보이는지를 분석했으며, 그 결과는 크게 다음의 두 가지 차원으로 요약된다. 먼저, 종이신문의 보도 양상에 견주어, <다음아고라> 토론은 과도한 ‘선정적 단어’ 사용, 부정적 인식 일색의 ‘미래 전망’, 그리고 ‘국내 전문가’ 중심의 제한된 ‘정보원 활용’이라는 한계를 드러내고 있었다. 다음으로, 미디어 프레임에 있어 <다음 아고라>는 개성공단 사태의 ‘배경 및 원인’과 ‘결과’ 프레임에서 종이신문과 일정한 유사성을 보이면서도, 종이신문에서는 드러나지 않았던 보다 다양한 프레임을 제공함으로써 그 내용적 다양성과 차별화를 보여주고 있었다. 특히, 이와 같은 내용적 대안성은 사태의 ‘해결 방안’으로 ‘고립 전략’이라는 차별화된 프레임에서 두드러졌 는데, ‘대화유도’에 방점을 둔 종이신문과 큰 간극을 보여주었다. 결론적으로 이 연구는 온라인 커뮤니티의 대안적 미디어로서의 역할과 기능이 토론 난제에서도 일정 부분 발휘될 수 있다는 것을 시사받을 수 있었으며, 이로써 온라인 토론의 질적 수준을 어느 정도 긍정적으로 평가할 수 있었다. The possibilities of the alternative media of the online community are mainly mediated from various communication factors besides the media technological aspects like the openness and the autonomy. Of these communication factors, this paper focused on the attribution of the debate subjects, and adopted Kaesong Industrial Complex Accident(KICA) regarded as the theme of the debate difficulty which has low accessibility to get information and is hard to take opinion diversities for its own users to see that online community could still play a roles as alternative media. For this, the research has compared <Daum Agora> to the main newspapers such as <Donga>, <Seoul> and <Hankyoreh> representing the territories of their ideological spectrum in South Korea to see how they had appealed their perspective on KIVA in terms of the media manners and frames. The main findings can be summarized as followings. <Daum Agora> presented many problems in the debate such as the usage of the yellow expressions, the negative-most future expectation, the using narrow sources when comparing to the major newspaper coverages. However, the analytic results on media frames was somewhat different from the analysis of media manner. Media frames on the causes and results of <Daum Agora> on the KICA were similar with the newspapers , but revealed more breadth of the opinion and showed contextually differentiation. Especially, these breadth and differentiation mainly appeared in the providing Solution of the Accident. These findings made us possible conclude that the online community debate could be qualified as the alternative media even in the theme of the debate difficulty .