• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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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.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.5
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04a
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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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• v.54 no.2
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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.

• International conference on construction engineering and project management
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• 2005.10a
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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.

• International conference on construction engineering and project management
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• 2005.10a
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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.

• International conference on construction engineering and project management
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• 2017.10a
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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.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.323-328
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• 2004

Domestic Design-Build, which has applied for client's convenience, has many problems Because It is being applied in the building law, which devides between architects and contractors. Among problem the relation between architects and contractors is a typical problem. It makes a quality decline and a design skill decline. In result, it causes insufficience of competitive power in overseas projects from now on. So we present the plans to improve mutual relations between architects and contractors. And we induce development of design skill and good quality of building by presenting a coordinative committee model between them in Design-Build projects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.103-109
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• 2017

Metal 3D printing, which is an additive metal manufacturing (AMM) process, enables the development of full-density metallic tools and parts using metal powders that are precisely delivered and controlled for deposition with no powder bed. However, some unknown geometric defects and irregular geometric features on an STL model can possibly result in incorrect metal part fabrication after the build. This study first proposes a methodical approach for verifying the build part, including the missing facet problems in an STL model, by defining some irregular features that possibly exist on the part. Second, 2D tool paths on each build layer were investigated for detecting any singular region inside the layer. The method was implemented for building two sample STL models using a direct energy deposition process, and finally, it was visually simulated for diagnosis.

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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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°.