• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1833-1836
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• 2008

Recently as the micro surface features become higher and diverse in their shapes, the releasing of the molded features becomes more crucial for manufacturing of the micro patterned products. The higher aspect ratio of the features or more complex shape of the features results in larger releasing force, elongation or cohesive failure of the features during the releasing. Another issue would be the uniformity of the released surface features after molding, especially for applications with large area surface. The micro patterned optical film, one of typical applications for micro surface features, consists of two layers, the thermoplastic base film and the micro formed UV resin layer. Therefore two interfaces are typically involved during the forming of this micro featured film; one is between the base film and the UV resin and another is between the resin and the pattern master. To improve the releasing of the molded surface features, the adhesive characteristic was investigated at these two interfaces. A PET film was used as a base film and two UV curable resins with different surface energy were prepared for different adhesiveness. Also the two different pattern masters were employed; one is made from brass-copper alloy and fabricated with PMMA. The adhesiveness at each interface was measured for some combinations of these base film, UV resins and the masters and the effect of this adhesiveness on the releasing was investigated.

• 마이크로전자및패키징학회지
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• 제27권1호
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• pp.25-29
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• 2020

광화학증착법 (PMOD; photochemical metal-organic deposition)을 이용하여 photoresist 및 etching 공정없이 pattern 된 TiO_x resistive switching (RS) 소자를 제작 및 그 특성을 평가하였다. Ti(IV) 2-ethylhexanoate를 출발물질로 사용하였으며 UV 노출시간 10 min에 광화학반응이 완료됨을 FTIR 분석을 통하여 확인하였다. 200 ℃ 이하 저온공정에서 직접패턴 된 20 nm 두께의 비정질 TiO_x 박막의 균일한 두께의 패턴형성을 Atomic Force Microscopy를 통하여 확인하였다. 별도의 상형성을 위한 후 열처리 공정 없이 4 ㎛ 선폭의 전극위에 형성된 20 nm 두께의 비정질 TiO_x RS 소자는 4V 동작전압에서 on/off ratio 20의 forming-less RS 특성을 나타내었다. Electrochemical migration에 영향을 미치는 grain boundary가 없어 소자간 신뢰성 향상이 기대되며, flexible 기판 또는 저온공정이 요구되는 메모리 소자 공정에서 PMOD 공정이 응용될 수 있음을 보여준다. Selector를 이용하여 crossbar array 구조를 도입할 경우 매우 간단한 구조의 저비용 메모리 소자를 구현할 수 있을 것으로 기대 된다.

• 한국세라믹학회지
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• 제39권9호
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• pp.884-889
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• 2002

나노 결정질 $ZrO_2$ 박막을 제조하여 박막의 표면에서 인산칼슘을 유도하는 능력을 편가하기 위하여, 지르코늄 나프테네이트를 출발물질로 사용하고 화학적 용액법을 이용하여, $ZrO_2/Si$ 구조를 제작하였다. 코팅용액을 (100)Si 기판 위에 스핀코팅한 후, 500$^{\circ}C$에서 10분간 전열처리와 800$^{\circ}C$에서 30분간 최종열처리를 행하였고, 모든 열처리는 공기분위기에서 실시하였다. X-ray diffraction analysis를 이용하여 열처리된 박막의 결정화도를 조사하였고, 표면의 미세구조와 표면 거칠기를 field emission-scanning electron microscope와 atomic force microscope를 이용하여 관찰하였다. 열처리 후의 박막은 표면에 미세한 $ZrO_2$ 나노 결정이 생성되어 있었으며, 박막의 계면은 매우 균질 하였다. 유사생채용액에 1일 및 5일간 침적된 샘플의 표면위에 형성된 인산칼슘을 energy dispersive X-ray spectrometer를 이용하여 관찰하였고, fourier transform infrared spectroscopy를 이용하여 인산칼슘에 카본이 치환되어 있음을 확인하였다.

• 한국지반환경공학회 논문집
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• 제12권3호
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• pp.5-12
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• 2011

본 연구는 국내에서 사용되고 있는 대표적인 파형강판 단면에 대하여 구조적 성능을 검토해 본 후, 현재 국내 제강업체에서 생산 가능한 최대 강판 폭을 고려한 최적 형상의 파형강판 단면을 제안하였다. 파형강판 단면의 검토에는 AISI(1986)를 사용하여 강판의 전단력과 모멘트를 고려하여 최적 단면의 역학적 한계를 정하였고, 성형성과 형상, 성형 후의 강판의 폭과 성형 전의 강판의 폭의 비율을 고려하여 기하학적 한계를 정하였다. 기존 파형강판에 본 연구에서 개발한 최적단면 탐색 알고리즘을 적용하여 강판의 성능을 검토 해본 결과, 굽힘반지름이 76mm이고, 내부굽힘각이 $50^{\circ}$ 부근에서 허용하중과 단면이차모멘트가 가장 큰 값을 나타내는 것을 확인할 수 있었다. 또한 현재 국내의 강판 제작성을 고려하여 강판폭 1,550mm, 길이 4,700mm의 SS490 강재를 사용하여 최적 단면 탐색 알고리즘을 적용한 결과, 기존 파형강판보다 두 배 이상의 성능을 발휘할 수 있는 새로운 단면들을 개발하였다.

• 지역연구
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• 제6권1호
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• pp.11-38
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• 1990

The purpose of this thesis is, first to present the spatial division of labor in Korea and its mechanism, and second, to elucidate the organic integral relation between local labor market and local community by studing the mechanism that the spatial division of labor is projected into the individual lacal labor marker, and reproduction of labor force process in this local labor market. According to this purpose, the theoretical frame of this analysis is done, the positive analysis is made and Kumi is choosed as its analysis case area. The main data is from 'Survey Report on Manufacturing Idustry Wage Conditions' published by Minimum Wage Council, Ministry of Labour and from the questionnaires and interview on textile industry and electric electronics industry firms in Kumi Export Industrial Estate. The following are the results of this study. 1. The mechanism of spatial division of labor in Korea, seen through the employment structure index, is accelerating the regional discrimination by fixing the regional hierarchisation between Seoul (or Seoul Metropolitan Area as expanded Seoul) and other areas. But it is also developing highly the regional employment structure at the level of technical division of labor, since the spatial division of labor in Korea is leaded by large firms and influenced by the policy for regional development. 2. Local labor market is formed in Kumi area and its delimitation is Kumi city. The employment structure of Kumi local labor market is occupying lower hierarchy division at management hierachical level and occupying upper hierarchy division at the level of technical division of labor, and brand plants of large firs are determinating and dominating this emplogment structure. These bdranch plants of large firs are forming more favorable and stabel labor marker than locally controlled ploants in Kumi local labor market. But the reproduction of labor force process in Kumi local labor market is not fully carried out and leaked into central city, therefore Kumi is now becoming an unstable local community, suffering from large movement of population. This is because Kumi local labor market is found not for itself, but by the state policy and externally controlled plants of large firms, and therefore no potentiality to control and to absorb the exterior influences is built in Kumi local labor market. 3. The case firms A, B have spatial division of labor between decision-making function and production function, and between upper management hierachical labor force and lower management hierachical labor force in internal labor market.

• Steel and Composite Structures
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• 제36권2호
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• pp.119-141
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• 2020

In this paper, wavy square absorbers were experimentally and numerically investigated. Numerical simulations were performed with LS-Dyna software on 36 wavy absorbers and their crushing properties were extracted and compared with the simple one. The effect of different parameters, including wave height, wave depth, and wave type; either internal or external on the crushing characteristics were also investigated. To experimentally create corrugation to validate the numerical results, a set of steel mandrel and matrix along with press machines were used. Since the initial specimens were brittle, they were subjected to heat treatment and annealing to gain the required ductility for forming with mandrel and matrix. The annealing of aluminum shells resulted in a 76%increase in ultimate strain and a 60% and 56% decrease in yield and ultimate stresses, respectively. The results showed that with increasing half-wave height in wavy square absorbers, the maximum force was first reduced and then increased. It was also found that in the specimen with constant diameter and half-wave depth, an increment in the half-wave height led to an initial increase in efficiency, followed by a decline. According to the conducted investigations, the lowe maximum force can be observed in the specimen with zero half-wave depth as compared to those having a depth of 1 cm.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.3.2-3.2
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• 2011

In recent years, inkjet printing technology has received significant attention as a micro/nanofabrication technique for flexible printing of electronic circuits and solar cells, as well for biomaterial patterning. It eliminates the need for physical masks, causes fewer environment problems, lowers fabrication costs, and offers good layer-to-layer registration. To fulfill the requirements for use in the above applications, however, the inkjet system must meet certain criteria such as high frequency jetting, uniform droplet size, high density nozzle array, etc. Existing inkjet devices are either based on thermal bubbles or piezoelectric pumping; they have several drawbacks for flexible printing. For instance, thermal bubble jetting has limitations in terms of size and density of the nozzle array as well as the ejection frequency. Piezoelectric based devices suffer from poor pumping energy in addition to inadequate ejection frequency. Recently, an electrohydrodynamic (EHD) printing technique has been suggested and proposed as an alternative to thermal bubble or piezoelectric devices. In EHD jetting, a liquid (ink) is pumped through a nozzle and a strong electric field is applied between the nozzle and an extractor plate, which induce charges at the surfaces of the liquid meniscus. This electric field creates an electric stress that stretches the meniscus in the direction of the electric field. Once the electric field force is larger than the surface tension force, a liquid droplet is formed. An EHD inkjet head can produce droplets smaller than the size of the nozzle that produce them. Furthermore, the EHD nano-inkjet can eject high viscosity liquid through the nozzle forming tiny structures. These unique features distinguish EHD printing from conventional methods for sub-micron resolution printing. In this presentation, I will introduce the recent research results regarding the EHD nano-inkjet and the printing system, which has been applied to solar cell or thin film transistor applications.

• Design & Manufacturing
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• 제14권3호
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• pp.50-56
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• 2020

Ceramic tile is widely used as a floor or interior decoration of buildings. The main processes are raw material blending, molding, drying, firing, etc., and since dimensional and quality stability are very important, they are generally molded by a dry press method. In ceramic tile molds, there is a liner that can be easily replaced in case of wear. The liner is constantly abrasion due to a continuous pressing process during tile forming, and it is required to be replaced every certain period. Even in the liner, use a wear-resistant fitting material only in areas where wear is concentrated. However, there was a risk that the fitting material was applied to large-sized tile molding due to problems such as damage to the molding machine and decrease in productivity when detached during the actual tile molding process due to weak fitting strength with the liner. Therefore, in this study, thermal-structural analysis for fitting tolerance analysis and structural analysis for fitting force analysis were performed for the shrink fit process of the fitting material.

• 한국농촌건축학회논문집
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• 제13권3호
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• pp.73-80
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• 2011

This study aims to develop furniture industry in eastern district of Gangwondo and a city of Gangneung and Donghae. Case study on furniture complex in Asahikawa, Japan and survey of furniture companies in Gangneung and Donghae city were implemented for understanding of present state, followed by analysis of problems. It can be summarized as follows. First, the basic operation method of Japanese furniture industry is to keep a balance between industry and academy. Universities or centers are in charge of education and fostering talents, such as allowing to promote and to sell products in design center gallery while corporations support it by lending expensive devices and conducting strength test analysis. Second, according to the survey of furniture companies in Gangneung, many difficulties in products development such as a shortage of designer, method, creative design were discovered. With respect to education and human force fostering, education for design and e-commerce were not sufficient, also marketing section has a problem with limited space for display and selling. Corporate support section is facing problems in receiving raw materials, aging of facilities, manufacturing and management methods. Consequently, it is considered that academic and industrial sections should implement their own roles by forming a bilateral network which connects local universities, high schools, relevant organization in the city and providence and furniture manufacturing companies to companies' product development, human force fostering and marketing in an attempt to activate the furniture industry in this area.

• 한국융합학회논문지
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• 제12권7호
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• pp.235-241
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• 2021

헤어미용을 통한 외모 관리는 미용산업의 근간(根幹)을 이루면서 열을 이용한 퍼머넌트 웨이브는 헤어살롱에서 많이 시술되고 있지만, 열 퍼머넌트 웨이브 시술로 인한 모발 손상은 불가피한 현실이다. 따라서 모발 웨이브 형성력을 더욱 높일 수 있고 고객의 모발 손상을 최소화할 수 있는 열 퍼머넌트 웨이브에 대한 효율적인 방안을 제시할 목적으로 본 연구를 진행하였다. 후두부의 버진 헤어를 채취하여 thermal rod pretreatment and thermal permanent wave treatment를 한 후, Atomic Force Microscope를 통한 모발 거칠기 분석과 3D-image를 연구하였다. 연구 결과 평균 거칠기(Ra)와 십점 평균 거칠기(Rz) 모두 4구간이 각각 223nm와 853nm로 산출되면서 가장 높은 수치를 나타냈다. 실험 데이터의 표본이 적은 한계성을 지니고 있으나 본 연구를 통해 웨이브 형성력을 더욱 상승시킬 수 있으며, 고객 모발의 큐티클 보호와 함께 모발 손상을 최소화할 수 있는 열 퍼머넌트 웨이브에 대한 객관적인 방안 제시가 현실적으로 가능해질 것으로 판단한다.