• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.96-102
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• 2005

The tribocharge build-up in the slider disk interface can cause ESD (electrostatic discharge) damage. In turn, ESD can cause severe melting damage to MR or GMR heads. We investigated the tribovoltage/current build-up with smooth and textured disks in HDD, operating at increasing disk accelerations. We found that tribe-voltage/current were generated during pico-slider/disk interaction and those levels were about 0.1 ${\~}$ 0.3 V and 10 ${\~}$ 40 pA, respectively. Tribovoltage/current were abruptly increased and dissipated within the acceleration time in the case of textured disk but in the case of smooth disk tribovoltage was continuously increased until the end of uniform velocity region and the tribocurrent did not dissipate within the acceleration time. In the case of textured dist tribovoltage/current was reduced with increasing disk acceleration, but in the case of smooth disk it was increased.

• 대한산업공학회지
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• 제41권5호
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• pp.470-480
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• 2015

There are many challenges in manufacturing system for new factory construction. Although factories produce same product, the layout of each factory may be different. The body shop in an automotive factory is a typical flow line with assembly, but the layout concept of the line varies among factories. In this paper, two types of layouts in the body shops of automotive factories, one for layered build and the other for modular build, are compared using simulation study. The simulation experiments indicate that the modular build layout is better than the layered build layout with respect to production rate. The effects of various failure distributions on the throughputs are also investigated, and some insights are suggested regarding the layout concept.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.552-558
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• 1995

Stereolithography is a process used to rapidly produce polymer components directly from a computer-representation of the part. There are several considerations to be made for the efficient use of te process. Especially, the build-up orientation of part critically affect to the part accuracy, total build time and the volume of support structures. Te purpose of this study is to determine the optimal build-up part orientation for the SLA process with improving part accuracy, minimizing total build time, and the volume of supprot structures. The first factor is related to the area of surfaces which have staircase protrusions after solidification, the second factor is related to the total number of layers, and the third factor is related to the area of the surfaces which need to be supported with support structures. An algorithm is developed to calculate the staircase area with quantifying the process planning errors that the volume of materials is supposed to be removed or added to the part, and the optimal layer thickness for the SLA system whichcan hadle the variable layer thickness in different orientations achieved by rotating the given part to the specified finite directions. So the optimal part orientation is determined based on the user's selections of primary criterion and the optimal thickness of layers is calculated at any part orientations.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.674-680
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• 2022

In the present study, radiation shielding and protection ability of prepared Flyash-lime-Gypsum (FaLG) bricks has been studied in terms of energy exposure build up factors and dose parameters. The energy exposure build up factors of Flyash-lime-Gypsum (FaLG) bricks have been calculated for the energy range of 0.015 MeV-15 MeV and for penetration depth upto 40 mfp directly using a new and simplified Piecewise Linear Spline Interpolation Method (PLSIM). In this new method, the calculations of G.P fitting parameters are not required. The verification and accuracy of this new method has been checked by comparing the results of exposure build up factor for NBS concrete calculated using present method with the results obtained by using G.P fitting method. Further, the relative dose distribution and reduced exposure dose rate for various radioactive isotopes without any shielding material and with Flyash-lime-Gypsum (FaLG) bricks have been calculated in the energy range of 59.59-1332 keV. On the basis of the obtained results, it has been reported that the prepared Flyash-lime-Gypsum (FaLG) bricks possess satisfactory radiation shielding properties and can be used as environmentally safe storage facilities for low level nuclear waste.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.1150-1153
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• 2005

The orders of Design-Build Delivery System (DBDS) in a large and public construction project have been increasing. Single Source Responsibility (SSR) for design and construction, which contributes to quality improvement of design and construction, has been performed. The DBDS performs SSR for design and construction, but, it has not maximized effect because of the dissatisfied alternative analysis procedures which are based on constructability evaluation and the information system in the design step. In this research, Constructability Evaluation Factors (CEFs) that must be evaluated, investigated, and reflected in the basic design step for design-build projects. The CEF proposed and the business process of each conductor has been systematized. To propose constructability evaluation factors, first classify drawing information by the constructability evaluation sphere. CEFs must be proposed to evaluate factors according to interference among work items. Second, applicable CEFs must be classified by preference ranking and weight. Third, the values of constructability factors in accordance with building elements and work items, need to be calculated. Finally, the CEFs proposal will support rational decision making, design cost reduction, and quality improvement through the values for constructability of building elements and work items.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.1007-1012
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• 2005

Although the design-build (DB) delivery system has been taking great strides in the world and relevant researches have also been quite abundant, few studies have dealt with its potential impacts on the construction industry as a whole. This research first identified the potential entry barrier factors, which may hinder the market access, based on the theory of industrial economics and characteristics of DB project. Then through a nation-wide questionnaire survey involving 103 construction contractors and engineering consultants, the influences of each factor on company's competitiveness and corporate strategies were scrutinized, and consequently, the evolution of the construction industry was examined. It is found that as opposed to the traditional design-bid-build delivery system, the DB delivery system elevates competitive advantages of large organizations in terms of the financial capability, working experience, human resource, and administrative strength, and among them, the financial strength was concluded to be the most significant force in differentiating corporate strategies and widening the gap of competitiveness between companies. It is inferred if the government extensively adopts DB delivery system, large organizations that already possess the competitive advantage tend to obtain both design and construction abilities, and dominate the DB market. Small and medium sized companies will find little room to maneuver and be forced to become specialty sub-contractors.

• 국제학술발표논문집
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• The 7th International Conference on Construction Engineering and Project Management Summit Forum on Sustainable Construction and Management
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• pp.153-158
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• 2017

Procurement system of public construction projects in Japan is changing with diversity in rapid pace. The quality assurance and risk management of construction projects should be more certain as the projects are turning into larger scale and more complexed. The clients in the public sector will want to make the relation of responsibility among the client, the designer (architects and engineers), and contractor clearer in terms of role and risk. Public-Private Partnership (PPP) is one of the methods for collaboration of the public sector and the private sector in public construction projects where the public utilizes the ability and suggestion of the private. Private Finance Initiative (PFI), Design-Build-Operate (DBO), market testing, designated manager system, outsourcing of tasks in local governments are well-known as examples of PPP in Japan. Indeed, there is an obvious trend that Design-Build (DB) is adopted in public construction projects in many countries including Japan. In this paper, the public construction projects in various procurement systems are surveyed and analyzed. They are not limited within the traditional procurement, Design-bid-Build, a separate order system of design and construction. Design-Build or PFI are adopted. In particular, contract by wide range including maintenance of equipment can be found. On the other hand, modification from originally typical PFI is taking place, such as concept design and project finance are removed from the roles and the tasks of the special purpose company (SPC) in PFI. Standard roles and tasks in a construction project are modeled in this paper.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.323-328
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• 2004

설계시공일괄공사(Design-Build)는 변화하는 건설 환경에 적합한 대안의 하나로서 현재 정부발주공사는 물론 민간에서까지 적용이 확대되고 있는 건설계약방식이다. 하지만 아직 국내의 실정에 적합하지 않아 많은 문제점들이 야기되고 있다. 그 중 설계자와 시공자간의 관행적인 문제점에 대해서는 아직 연구가 미흡하여 본 연구를 진행하게 되었다. 국내에서는 시공자가 설계자를 고용하여 설계자를 시공자 조직의 일부로 예속시킨 후 시공자가 설계조직에게 관리자를 파견하여 설계업무를 조정하고 있는데 이로 인해 실시설계자로 선정되는데 가장 중요한 요소인 설계자의 입지가 좁아져 양자간의 교류가 불량하고 대형공사에서 설계기술 발전에 많은 저해소요를 지니고 있다. 이에 본 연구에서는 이러한 설계자와 시공자 사이의 문제점을 분석하여 재조명해 보고 이러한 상호 관계를 개선시킬 기본 요소와 함께 이들 조직을 중간에서 컨트롤 할 수 있는 '중간 협의체'라는 것을 제시함으로서 현행 체제 속에서 양자의 관계를 개선시킬 방안을 제시하였다.

• 대한기계학회논문집A
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• 제41권2호
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• pp.103-109
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• 2017

AMM(Additive Metal Manufacturing)이라 호칭되는 3차원 금속 프린팅(metal 3-D printing) 공정은 금속분말(metal powder)을 적층 재료로 사용하여 기계적부품용 실형상 금속 파트(metallic parts)를 직접 조형하여 제조한다. 한편, 조형 파트형상의 STL모델에 존재하는 기하학적 오류들과 특징형상들의 특이성으로 인하여 조형 작업 중에 내부에 결함들이 포함된 실형상 파트가 조형될 가능성이 존재하게 되며 이로 인해 3차원 금속 프린팅 조형공정 자체의 신뢰성에 문제를 야기할 수 있다. 본 논문에서는 이러한 조형작업 중 발생할 수 있는 결함들을 미리 진단, 분석하고 수정하기 위하여 첫째, 조형 전에 STL 형상모델의 진단분석을 통하여 결함요소를 사전에 탐지하고 둘째, 적층 단면내 조형 공구 경로상에 실제로 포함된 결함들을 분석하고 이를 수정하기 위한 조형 파트 진단 및 조형 공구 경로 검증 연구방법을 제시하였다. 또한 DED(direct energy deposition) 공정을 기준으로 2가지 STL 형상파트 사례들에 대하여 제시한 연구방법의 case study를 수행하였다.

• The Journal of Advanced Prosthodontics
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• 제12권4호
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• pp.225-232
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• 2020

PURPOSE. This study aimed to fabricate provisional crowns at varying build directions using the digital light processing (DLP)-based 3D printing and evaluate the marginal and internal fit of the provisional crowns using the silicone replica technique (SRT). MATERIALS AND METHODS. The prepared resin tooth was scanned and a single crown was designed using computer-aided design (CAD) software. Provisional crowns were printed using a DLP-based 3D printer at 6 directions (120°, 135°, 150°, 180°, 210°, 225°) with 10 crowns in each direction. In total, sixty crowns were printed. To measure the marginal and internal fit, a silicone replica was fabricated and the thickness of the silicone impression material was measured using a digital microscope. Sixteen reference points were set and divided into the following 4 groups: marginal gap (MG), cervical gap (CG), axial gap (AG), and occlusal gap (OG). The measurements were statistically analyzed using one-way ANOVA and Dunnett T3. RESULTS. MG, CG, and OG were significantly different by build angle groups (P<.05). The MG and CG were significantly larger in the 120° group than in other groups. OG was the smallest in the 150° and 180° and the largest in the 120° and 135° groups. CONCLUSION. The marginal and internal fit of the 3D-printed provisional crowns can vary depending on the build angle and the best fit was achieved with build angles of 150° and 180°.