• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2000년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.9-10
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• 2000

An important business-field of world-wide steel-industry is the coating of thin metal-sheets with zinc, zinc-aluminum and aluminum based materials. These products mostly go into automotive industry. in particular for the car-body. into building and construction industry as well as household appliances. Due to mass-production, the processing is done in large continuously operating plants where the mostly cold-rolled metal-strip as the substrate is handled in coils up to 40 tons unwind before and rolled up again after passing the processing plant which includes cleaning, annealing, hot-dip galvanizing / aluminizing and chemical treatment. In the liquid Zn, Zn-AI, AI-Zn and AI-Si bathes a combined action of corrosion and wear under high temperature and high stress onto the transfer components (rolls) accounts for major economic losses. Most critical here are the bearing systems of these rolls operating in the liquid system. Rolls in liquid system can not be avoided as they are needed to transfer the steel-strip into and out of the crucible. Since several years, ceramic roller bearings are tested here [1.2], however, in particular due to uncontrollable Slag-impurities within the hot bath [3], slide bearings are still expected to be of a higher potential [4]. The today's state of the art is the application of slide bearings based on Stellite\ulcorneragainst Stellite which is in general a 50-60 wt% Co-matrix with incorporated Cr- and W-carbides and other composites. Indeed Stellite is used as the bearing-material as of it's chemical properties (does not go into solution), the physical properties in particular with poor lubricating properties are not satisfying at all. To increase the Sliding behavior in the bearing system, about 0.15-0.2 wt% of lead has been added into the hot-bath in the past. Due to environmental regulations. this had to be reduced dramatically_ This together with the heavily increasing production rates expressed by increased velocity of the substrate-steel-band up to 200 m/min and increased tractate power up to 10 tons in modern plants. leads to life times of the bearings of a few up to several days only. To improve this situation. the Mechanical Alloying (MA) TeChnique [5.6.7.8] is used to prOduce advanced Stellite-based bearing materials. A lubricating phase is introduced into Stellite-powder-material by MA, the composite-powder-particles are coated by High Energy Milling (HEM) in order to produce bearing-bushes of approximately 12 kg by Sintering, Liquid Phase Sintering (LPS) and Hot Isostatic Pressing (HIP). The chemical and physical behavior of samples as well as the bearing systems in the hot galvanizing / aluminizing plant are discussed. DependenCies like lubricant material and composite, LPS-binder and composite, particle shape and PM-route with respect to achievable density. (temperature--) shock-reSistibility and corrosive-wear behavior will be described. The materials are characterized by particle size analysis (laser diffraction), scanning electron microscopy and X-ray diffraction. corrosive-wear behavior is determined using a special cylinder-in-bush apparatus (CIBA) as well as field-test in real production condition. Part I of this work describes the initial testing phase where different sample materials are produced, characterized, consolidated and tested in the CIBA under a common AI-Zn-system. The results are discussed and the material-system for the large components to be produced for the field test in real production condition is decided. Outlook: Part II of this work will describe the field test in a hot-dip-galvanizing/aluminizing plant of the mechanically alloyed bearing bushes under aluminum-rich liquid metal. Alter testing, the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed. Part III of this project will describe a second initial testing phase where the won results of part 1+11 will be transferred to the AI-Si system. Part IV of this project will describe the field test in a hot-dip-aluminizing plant of the mechanically alloyed bearing bushes under aluminum liquid metal. After testing. the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed.

• Journal of Gastric Cancer
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• 제12권4호
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• pp.237-242
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• 2012

Purpose: Despite the great advances in laparoscopic techniques, most active general surgeons do not apply laparoscopic surgery in the treatment of duodenal ulcer perforation when facing a real-life emergency. Therefore, our study was designed to evaluate the feasibility of laparoscopic surgery in duodenal ulcer perforation, and provide a step-by-step protocol with tips and recommendations for less experienced surgeons. Materials and Methods: Between March, 2011 and May, 2012, 21 patients presenting with duodenal ulcer perforation underwent laparoscopic primary repair with omentopexy. There were no contraindications to perform laparoscopic surgery, and the choice of primary repair was decided according to the size of the perforation. The procedure for laparoscopic primary repair with omentopexy consisted of peritoneal lavage, primary suture, and omentopexy using a knot pusher. Results: During the operation, no conversion to open surgery or intra-operative events occurred. The median operation time was 45.0 minutes (20~80 minutes). Median day of commencement of a soft diet was day 6 (4~17 days). After surgery, the median hospital stay was 8.0 days (5~27 days). Postoperative complications occurred in one patient, which included a minor leakage. This complication was resolved by conservative management. Conclusions: Although our study was carried out on a small number of patients at a single institution, we conclude that laparoscopic primary repair can be an effective surgical method in the treatment of duodenal ulcer perforation. We believe that the detailed explanation of our procedure will help beginners to perform laparoscopic primary repair more easily.

• 전자공학회논문지
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• 제53권8호
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• pp.119-126
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• 2016

본 논문에서는 의복용 무선전력전송 시스템을 구축을 위한 평면형 직물공진기를 제안하고, 공진기에 사용된 의복용 직물기판의 재질별 특성을 분석하였다. 평면형 직물공진기는 공진주파수가 1-10 MHz가 되도록 직물기판 위에 전도성 물질로 루프 및 코일을 평면 설계하였다. 의복용으로 많이 사용되고 있는 폴리에스테르 섬유와 면을 직물기판으로 사용하였으며, 평면 루프와 코일은 동테이프(copper tape)와 실버페이스트(silver paste)로 설계하였다. 자기공진형 무선전력전송 시스템에 적용된 직물의 재질별 특성을 분석하기 위해 송신부와 수신부를 대칭으로 설계하였다. 실험 결과, 낮은 유전상수 및 비교적 두꺼운 두께를 가진 직물기판과 표면저항이 작은 도체성 재질의 패턴(루프 및 코일)으로 제작되었을 때, 의복용 무선전력전송 시스템이 높은 전송효율을 보였다. 본 연구를 통해 제안된 평면형 직물 공진기는 무선전력전송 기술의 영역을 의복용으로 넓힐 수 있는 가능성을 보여주었다.

• 컴퓨터교육학회논문지
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• 제20권6호
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• pp.17-25
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• 2017

2015 개정 교육과정이 현장 학교에 성공적으로 안착할 수 있도록, 국가차원에서 2015, 2016년에 68개의 SW연구학교를 운영하고 SW교육의 효과성을 측정하기 위한 검사도구가 개발되었다. 본 연구는 기존에 개발된 컴퓨팅 사고력 검사 도구 분석을 통해 2018년부터 실시되는 교육과정의 효과성을 검증할 수 있는 컴퓨팅 사고력 검사도구의 방향성을 제시하는 것에 목적이 있다. 분석결과, 기존에 사용된 검사도구는 컴퓨팅 사고력 기반의 문제해결과정을 측정하기 위한 능력요소의 타당성은 부족하였다. 문항특성 분석 결과, 변별도는 양호하였으나, 난이도는 쉬운 문항의 비율이 높아 학생들의 역량을 정확히 측정하기는 부족하였다. 결과를 토대로 본 연구는 컴퓨팅 사고력 기반의 문제해결과정을 고려한 문항개발, 학생들의 경험적 지식 활용, 실생활의 소재로 사고력의 흐름을 확인할 수 있는 구성을 제안하였다.

• 복식문화연구
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• 제15권5호
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• pp.902-915
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• 2007

This study examines decorative features found in the traditional costume of the Miao, one of the minority groups in China, and adapts them for the development of modern Korean-style fashion designs in order to present visual sample data and to introduce techniques. As for the research method, both literature and visual data are examined: the former includes Miao-related books and theses; the latter, pictures from various documents and real-life data in the possession of Seoul Women's University. The study result is as follows: 1. The basic structure of Miao costume is consist of a Caftan-type upper garment and an accentuated lower garment, pleats skirt although they are decorated luxuriously with various techniques such as delicate embroidery and dyeing. 2. Details and trimmings in modern shapes are developed and presented by adding modern materials to satin, twists, cross-stitch embroidery, stripe patterns, geometrical patchwork, machine pleats and smoking, trimmings of fringe & feather, and the border line decoration of coloration, braids, piping, embroidery, belts tied and wound with colorful threads. 3. Detachable accessaries such as front reinforcement strips, back reinforcement strips, belts, decorative aprons and patchwork skirts are developed and designed by adapting highlighted layered effects. 4. The silver decoration used as an necessary by the Miao is suitable for modern fashion design in futuristic sense. Various techniques and decorative features of Miao costume display their true value all the more in modern fashion stream in which ethnic trends draw much attention.

• 한국지구과학회지
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• 제31권5호
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• pp.500-520
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• 2010

The purposes of this case study were (1) to explore one experienced teacher's views on Earth Systems Education and (2) to describe and document the characteristics of the Earth Systems Education (ESE) curriculum provided by an exemplary middle school science teacher, Dr. J. All the essential pieces of evidence were collected from observations, interviews with the experienced teacher and his eighth grade students, informal conversations, document analysis, and field notes. The $NUD^*IST$ for MS Windows was used for an initial data reduction process and to narrow down the focus of an analysis. All transcriptions and written documents were reviewed carefully and repeatedly to find rich evidence through inductive and content analysis. The findings revealed that ESE provided a conceptual focus and theme for organizing his school curriculum. The curriculum offered opportunities for students to learn relevant local topics and to connect the classroom learning to the real world. The curriculum also played an important role in developing students' value and appreciation of Earth systems and concern for the local environment. His instructional strategies were very compatible with recommendations from a constructivist theory. His major teaching methodology and strategies were hands-on learning, authentic activities-based learning, cooperative learning, project-based learning (e.g., mini-projects), and science field trips. With respect to his views about benefits and difficulties associated with ESE, the most important benefit was that the curriculum provided authentic-based, hands-on activities and made connections between students and everyday life experiences. In addition, he believed that it was not difficult to teach using ESE. However, the lack of time devoted to field trips and a lack of suitable resource materials were obstacles to the implementation of the curriculum. Implications for science education and future research are suggested.

• 한국실내디자인학회논문집
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• 제14권5호
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• pp.106-113
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• 2005

New images percolate through human consciousness by the media such as movies, TV programs, and brilliant advertisements. These images reproduce new ' things ' throughout the ' semantic processes ' by those who experience and recognize them. Alvin Toffler describes it as the ' information bomb ' and ' image fragments ' in his talk about the new paradigm of information-oriented era. The increasing number of images and their accelerating rate of appearance imply that images become more momentary, and are evidence that they are transforming entire human life and consciousness. Such awareness means a lot to a designer. Especially, the subject that how modern space-dominating images are related to the structure and materials constituting the space and communicate with human mind will be an important factor in establishing the human-space relationship in the future. Furthermore, the present age overspread with various medium is not the only one privileged of the images that exist within space. They are the results of continuous expansion of existing images, and also process of evolution of space powered by the fusion of images and digital media. Imagified space is a boundary layer of Cyberspace, and the space itself becomes an interface by human recognition and participation. Now, the functional classification of spaces such as ' office, ' ' cafe, ' and ' school ' is meaningless. Whatever it may be, the function of a space is defined by the information it interfaces, and therefore it becomes an interface to information through a large number of images. Based on this idea, we will observe the imagificaiton of space in the form of discussion, and from that, try to understand the phenomenon through the real world examples.

• 한국융합학회논문지
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• 제9권5호
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• pp.151-156
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• 2018

본 연구에서는 CFRP와 금속 또는 비금속을 접착제로 접합시켜 이 재료에 대한 파손 연구를 수행하였다. 그 해석 조건으로는 DCB 시험편을 이용하여 시험편의 상부에는 CFRP, 시험편의 하부에는 금속 또는 비금속 재료로 지정하였고 두 상부와 하부 사이를 구조용 접착제로 부착하는 것을 묘사하였다. 이 해석 결과로는 알루미늄으로 접착된 시험편에서 가장 작은 등가응력 보였고 티타늄을 사용하였을 때 박리된 CFRP시험편에서의 최대 전단응력은 가장 낮음을 보였다. 결론적으로 티타늄을 사용하였을 때 시험편의 변형이 가장 작은 것을 알 수 있었고 본 연구 결과를 토대로 접착제를 이용한 접착 계면의 파손데이터를 실생활에 융합하여 그 미적 감각을 나타낼 수 있다.

• 한국초등과학교육학회지:초등과학교육
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• 제39권2호
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• pp.183-203
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• 2020

The purpose of this study is to investigate the factor for improving elementary and secondary students' positive experiences about science (PES). In-depth interviews with 32 students and 8 teachers from 8 elementary and secondary Science Core schools were conducted to explore the factors for improving the student's PES. The analysis of the results reveal that the eight key factors which had a decisive impact on a student's PES were 'practice-centered exploratory activities', 'student-led class', 'positive and professional feedback', 'construction of knowledge through exploration', 'class considering student's interest and aptitude', 'use of materials related to real life', 'smooth communication and collaboration in group activities', and 'appropriate difficulty in learning content'. There were also five environmental factors that affected these key factors: 'teacher's professionalism for science classes', 'science class environment', 'teacher community in unit schools', 'change in curriculum', and 'scientific activities other than regular classes'. Based on these results, the practical implications for improving the student's PES are suggested.

• 한국학교수학회논문집
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• 제15권1호
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• pp.27-51
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• 2012

본 논문은 세 명의 초임교사들의 수학 수업에 나타난 교수학적 내용 지식을 수학내용지식, 학생이해지식, 교수법에 대한 지식이라는 측면에서 상세히 분석하였다. A교사는 부진아였던 학생 시절의 영향을 받아 구체물을 통한 개념 중심의 수업을 구현하고자 하였고, B교사는 수학자처럼 자신만의 사다리꼴의 넓이를 구해보는 탐구 중심의 수업을 구현하였으며, C교사는 실생활 중심 수업을 하였다. 세 명 교사들의 수학 수업에 나타난 교수학적 내용 지식은 구현하려고 하는 수업의 형태에 따라 상당한 차이를 보였다. 본 논문은 세 교사의 수학 수업에 대한 면밀한 분석을 통해 초임교사의 수학과 수업 전문성을 신장하기 위한 시사점을 제공하고자 한다.