표면처리조건이 CAD/CAM 지르코니아와 전장용 세라믹의 결합력에 미치는 영향

전우용(Woo-Yong Jeon),신재우(Jae-Woo Shin) 대한치과재료학회 2011 대한치과재료학회지 Vol.38 No.4

The purpose of this study was to investigate the effect of the surface treatment conditions on the bond strength between CAD/CAM zirconia and veneering ceramics. The debonding/crack initiation strengths between zirconia and veneering ceramics were measured according to ISO9693. To investigate the surface roughness changes with blasting pressure, zirconia plates were blasted with 70 μm alumina at pressure range from 2 .5 a tm t o 4.5 atm. E ighty zirconia p lates, 2 4.0 mm × 3.0 mm × 0.5 mm, were made with five CAD/CAM zirconia blocks, sandblasted with 70 μm alumina at 2.5 atm, and equally divided into two groups. One group (BHA) was heat-treated at 1000℃ for 10 minutes after acid-etching with 5 wt% HF solution for 10 minutes. Another group (BAH) was acid-etched with 5 wt% HF solution for 10 minutes after heat-treatment at 1000℃ for 10 minutes. Four different veneering ceramics of Cerabien CZR (CB), Lava Ceramic (LC), ICE Zirkon Ceramic (ZC) and Zirmax (ZM) were sintered on zirconia plates. The three point flexural test was performed at crosshead speed 1.5 mm/min. Zirconia surface blasted with 70 μm alumina abrasives showed the rough surface by eliminating the grains. Arithmetical average roughness value Ra of the zirconia surface blasted at 2.5 atm with 70 μm alumina abrasives was 0.304±0.036 μm which showed the significant difference with the group blasted at 3.5 atm. Maximum bond strength of 35.3 MPa was obtained at ZC group and the ZC and LC groups showed the significant differences with the CB and ZM groups. The debonding/crack initiation strengths between blasted zirconia and veneering ceramics were not significantly different with acid etching and heat treatments before and after monoclinic-tetragonal transformation.

Ti-6Al-4V 합금의 양극산화와 석회화 순환 처리에 의한 표면 개질

전우용(Woo-Yong Jeon),한아름(A-Lum Han) 대한치과재료학회 2016 대한치과재료학회지 Vol.43 No.1

The purpose of this study was to investigate the bioactivity of Ti-6Al-4V alloy, which was modified by an anodic oxidation and an cyclic precalcification treatments. The electrolyte solution was prepared by mixing 79 wt% ethylene-glycol with 20 wt% distilled water and 1 wt% NH4F. The anodic oxidation process was conducted at a constant potential of 10, 15, 20, and 25 V for 1 h at room temperature. A cyclic precalcification treatment was done by soaking in 0.05 M NaH2PO4 solution at 80℃ and saturated Ca(OH)₂ solution at 90℃ in turns. All samples were heat-treated at 500℃ for 2 hours. Bioactivity was evaluated by apatite forming ability in a simulated body fluid (SBF). The average diameter of nanotubes increased with increasing the applied voltage. The growth of nanotubes has slowed after 10 minutes following the rapid growth in the initial stage. Nanotubes had self-aligned form with dense structure composed of small and large diameter, their diameter at the bottom was bigger than that at the top. Bioactivity was accelerated through the cyclic calcification treatment in 0.05M NaH₂PO₄ solution at 80℃ and saturated Ca(OH)₂ solution at 90℃. In conclusion, it is the effective surface treatment method of Ti-6Al-4V alloy for improvement of bioactivity that calcium phosphate is precipitated by cyclic calcification in 0.05M NaH₂PO₄ solution at 80℃ and saturated Ca(OH)2 solution at 90℃ after formation of TiO₂ nanotubes in ethylene-glycol solution at 25 V.

양극산화와 석회화 전처리된 Ti-27Nb-10Ta-3.5Zr 합금의 생체활성도

전우용(Woo-Yong Jeon) 대한치과재료학회 2013 대한치과재료학회지 Vol.40 No.3

This study was performed to investigate the bioactivity of Ti-24Nb-17Ta-5Zr alloy modified by an anodic oxidation and an precalcification treatments. Ti-27Nb-10Ta-3.5Zr alloy was anodized to form the nanotubular TiO₂ layer. To increase the bioactivity, calcium phosphate deposition was carried out by an immersion treatment in 0.5 M CaHPO₄ solution at 90℃ for 30 min. Bioactivities were evaluated by the apatite forming ability in simulated body fluid (SBF) for 10 days. Nanotubular TiO₂ layer showed the dense and self-organized structure. Nanotubes showed the separately connected tube structures and it was opened and enlarged as going down. The bioactivity of nanotubular TiO₂ layer on Ti-27Nb-10Ta-3.5Zr alloy was improved with precalcification treatment in 0.5 M CaHPO₄ at 90℃. These results suggest that the bioactivity of Ti-27Nb-10Ta-3.5Zr alloy could be improved with the formation of nanotubular TiO₂ layer and the preecalcification treatment in 90℃ 0.5 M CaHPO₄ solution.

한국 근대의 華僑 문제

전우용(Jeon Woo-yong) 고려사학회 2003 한국사학보 Vol.- No.15

석재가공용 다이아몬드 톱의 제조 및 특성

이현우,전우용,이오연,설경원,Lee Hyun-Woo,Jeon Woo-yong,Lee Oh-yeon,Seol Kyeong-won 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.5

The purpose of the present study is to determine an optimum composition using cheaper powders keeping with high performance of hard rock cutting diamond saw blade. With 50Fe-20(Cu . Sn)-30Co specimen, a part of Co was replaced by Ni(5%, 10%, and 15%, respectively). These specimens were hot pressed and sintered for predetermined time at various temperature. Sintering is performed by two different methods of temperature controlled method and specimen dimension controlled method. In order to determine the property of the sintered diamond saw blade, 3 point bending tester, X-ray diffractometer, and SEM were used. As the Co in the bond alloy was replaced by Ni, the hardness of the specimen increased. Thus the 50Fe-20(CuㆍSn)-15Co-15Ni specimen showed the maximum hardness of 104(HRB). The results of 3 point bending test showed that flexure strength decreased along with increase in Ni content. This is attributed to the formation of intermetallic compound(Ni$_{x}$Sn) determined by X-ray diffraction. The fracture surface after 3 point bending test showed that diamond was fractured in the specimen containing 0%, 5%, and 10%Ni, and the fracture occurred at the interface between diamond and matrix in the specimen containing 15%Ni. The cutting ability test showed that the abrasive property was not changed in the specimen containing 0%, 5%, and 10%Ni. The optimum composition determined in this study is 50Fe-20(CuㆍSn)-20Co-10Ni.

유아들의 그림에 나타난 행복한 경험에 대한 인식

홍용희(HONG YONG-HEE),김혜전(Kim Hae Jeon),전우용(Jeun Woo Yong) 한국육아지원학회 2014 육아지원연구 Vol.9 No.4

본 연구는 유아들의 행복 경험 그림과 그림 이야기를 통해 유아들이 어떤 상황에서 행복한지, 행복을 느낄 때 함께 있는 인물은 누구인지를 분석함으로써 행복에 대한 유아들의 인식을 이해하고 행복 증진 방안과 실천의 토대를 마련하는 것을 목적으로 한다. 연구 참여자는 서울에 위치한 유치원 2개소와 어린이집 2개소의 만 3~5세 유아 310명이다. 연구결과를 살펴보면, 첫째, 유아들이 행복을 느꼈던 상황은 만족을 주는 놀이나 활동 참여, 중요한 타인과의 사회적 교류, 몸과 마음의 평안, 특별한 행사, 목표 성취 등으로 나타났다. 둘째, 유아들이 행복을 느낄 때 함께 있었던 인물은 부모 및 형제자매, 친구, 조부모 및 친척 등이며, 혼자 있을 때의 행복을 그린 유아들도 있었다. 이러한 연구결과는 유아들의 행복을 증진시키기 위해서는 유아들이 행복을 느낀다고 말하는 경험들을 풍부하게 제공해야 함을 시사한다. 또한 유아들이 행복의 진정한 의미를 알고 내면화하게 하려면 부모와 교사는 유아들이 자신들의 행복 구축뿐만 아니라 타인의 행복에도 기여하도록 교육해야 함을 시사한다. The purpose of this study was to analyze young children’s perceptions about happy experience based on their drawings. Analyzing in what kind of situation and with whom the young children feel happiness will help us to understand young children’s perceptions of happiness and lay a foundation that fosters young children’s happiness. The subjects include 310 young children aged 3-5 at two kindergartens and two daycare centers in Seoul. The results were as follows. First, young children were happy when playing and participating activities that give them satisfaction, engaging in social exchanges with significant others, and being comforted physically and emotionally. Other depictions of happiness included participating in special events and achieving goals. Second, the figures that most often appeared in the young children's drawings of happy experiences were parents and siblings, friends, grandparents and relatives, and the child him/herself. The findings of this study suggest that children should be provided many opportunities that they experience a sense of happiness to promote their own happiness. It also implies that parents and teachers should educate young children to not only create their own happiness, but also to contribute to the happiness of others in order for them to understand and internalize the real meaning of happiness.

폴리이미드와 Cu/Ni층과의 계면결합력에 미치는 플라즈마 처리 시간 효과

우태규 ( Tae Gyu Woo ),박일송 ( Il Song Park ),정광희 ( Kwang Hee Jung ),전우용 ( Woo Yong Jeon ),설경원 ( Kyeong Won Seol ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.8

This study represents the results of the peel strength and surface morphology according to the preprocessing times of polyimide (PI) in a Cu/Ni/PI structure flexible copper clad laminate production process based on the polyimide. Field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopywere used to analyze the surface morphology, crystal structure, and interface binding structure of sputtered Ni, Cu, and electrodeposited copper foil layers. The surface roughness of Ni, Cu deposition layers and the crystal structure of electrodeposited Cu layers were varied according to the preprocessing times. In the RF plasma times that were varied by 100-600 seconds in a preprocessing process, the preprocessing applied by about 300-400 seconds showed a homogeneous surface morphology in the metal layers and that also represented high peel strength for the polyimide. Considering the effect of peel strength on plastic deformation, preprocessing times can reasonably be at about 400 seconds.

전해액 조성에 의한 구리 박막의 표면형상과 물성변화

우태규 ( Tae Gyu Woo ),박일송 ( Il Song Park ),전우용 ( Woo Yong Jeon ),박은광 ( Eun Kwang Park ),정광희 ( Kwang Hee Jung ),이현우 ( Hyun Woo Lee ),이만형 ( Man Hyung Lee ),설경원 ( Kyeong Won Seo ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.10

This study examined the effect of copper and sulfuric acid concentrations on the surface morphology and physical properties of copper plated on a polyimide (PI) film. Electrochemical experiments with SEM and a four-point probe were performed to characterize the morphology and mechanical characteristics of copper electrodeposited in the composition of an electrolyte. The resistivity and peel strength were controlled using a range of electrolyte compositions. A lower resistivity and high flexibility were obtained when an electrolyte with 20 g/l of copper was used. However, a uniform surface was obtained when a high current density that exceeded 20 mA/cm² was applied, which was maintained at copper concentrations exceeding 40 g/l. Increasing sulfuric acid to >150 g/l decreased the peel strength and flexibility. The lowest resistivity and fine adhesion were detected at a Cu2+: H2SO4 ratio of 50:100 g/l.

만 5세 유아들의 권리에 대한 인식 탐구

이승연(Lee Seung Yeon),김혜전(Kim Hae Jeon),전우용(Jeun Woo Yong) 한국육아지원학회 2016 육아지원연구 Vol.11 No.3

본 연구는 만 5세 유아들이 인식하고 있는 권리의 개념과 특성, 유형을 탐색하는 것을 목적으로 한 질 적연구이다. 연구참여자는 서울 소재 유치원 1곳과 어린이집 1곳에 재원 중인 유아 70명이었으며, 연구기 간은 2013년 11월부터 2014년 2월, 연구방법은 소집단 면담이었다. 소집단은 4-6명으로 구성하였으며, 집 단 당 2회의 면담을 실시하였다. 면담에서는 권리의 개념, 유아에게 필요한 권리, 권리를 실행하지 못했던 경험, 권리 실현을 위해 필요한 것 등에 대해 개방적으로 이야기를 나누었으며, 자료분석은 Hatch (2002/2008)의 유형적 분석 모형에 근거하였다. 연구 결과, 첫째, 유아들이 인식하는 권리의 개념은 ‘필요 한 것을 갖는 것’과 ‘하고 싶은 것을 할 수 있는 것’으로 나타났다. 둘째, 유아들이 인식하는 권리의 특성 은 ‘노력과 책임이 필요한 것’과 ‘실현을 위해 도움이 필요한 것’이었다. 셋째, 유아들이 필요하다고 인식 한 권리는 ‘친밀한 사람과 긍정적인 관계를 맺을 권리’, ‘생존할 권리’, ‘기본적인 생활을 할 권리’, ‘위험으 로부터 보호받을 권리’, ‘건강하게 성장할 권리’, ‘좋아하는 것을 하고 즐거움을 추구할 권리’, ‘지적성장과 자아실현을 위해 노력할 권리’, ‘주체성을 발휘하고 의견을 존중받을 권리’의 8가지 유형으로 범주화되었 다. 본 연구는 만 5세 유아들의 목소리와 대화를 통해 권리에 대한 그들의 인식을 알아봄으로써 유아의 권리에 대한 사회적 이해를 높이고, 향후 유아권리 존중과 교육을 위한 기초적 토대를 제공하는데 의의가 있다. This qualitative study aims to explore young children’s perspectives on their rights in terms of notions, attributes, and categories. From November 2013 to February 2014, 70 young children at five-year-old classrooms in a kindergarten and a child care center in Seoul participated in this study through small group interviews. A small group consisted of 4 to 6 children, and interviews were conducted 2 times per group. In the small group interviews, the children were guided to talk openly about the notion of rights, the rights that young children should have, the experiences that they could not exercise their rights, and the essentials for exercising their rights. The data were analyzed based on Hatch’s typological analysis (2002/2008). The results of this study were as follows. First, the notions that the young children had on their rights were (1) to have basic necessities and (2) to be able to do what they want to do. Second, the attributes of the rights that the young children thought of were (1) the ones that need their efforts and responsibilities and (2) the ones that need others’ help to realize the rights. Third, the categories that they insisted on their rights were (1) the right to building positive relationships with close persons, (2) the right to survive, (3) the right to be guaranteed the basic essentials of life, (4) the right to be protected from danger, (5) the right to grow up healthily, (6) the right to pursue pleasure doing what they like to do, (7) the right to try for their intellectual growth and self-realization, and (8) the right to express their views freely and be respected as a person. By approaching 5-year-old children’s perspectives on their rights through their voices and conversations, we hope that the results of this study provide a foundation for increasing social understandings on the rights of young children and further for respect for their rights and education on their rights.

양극산화 불꽃방전 처리 후 열수처리한 티타늄 산화 피막의 특성

김남규(Nam-Kyu Kim),김종준(Jong-Jun Kim),전우용(Woo-Yong Jeon),박일송(Il-Song Park),이민호(Min-Ho Lee),배태성(Tae-Sung Bae) 대한치과재료학회 2004 대한치과재료학회지 Vol.31 No.3