• 소성∙가공
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• 제19권4호
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• pp.248-252
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• 2010

In this paper, three-dimensional finite element analysis of thread rolling process of a 12 point flange head bolt is conducted using a rigid-plastic finite element method based metal forming simulator AFDEX 3D. A whole sequence of cold forming processes of a long shaft bolt composed of four forging stages and final thread rolling process is simulated to reveal the mechanism of thread formation. A mesh density control function is applied near the major plastic deformation region to achieve computational efficiency. It has been shown both numerically and experimentally that longitudinal lengthening or shortening is negligible in thread rolling.

• 소성∙가공
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• 제16권4호
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• pp.244-249
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• 2007

The influence of powder compaction pressure on the hydraulic cylinder block fabricated by powder metallurgy is investigated in this study. The cylinder block is compacted with powder under various compaction pressures and then sintered, and its density and dimensions are measured to reveal the relationship of the powder compaction pressure with the product quality. Moreover, finite element analyses of the density distributions are carried out under the same conditions with the experiments and the predicted results are compared with the measured ones.

• 소성∙가공
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• 제20권6호
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• pp.461-467
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• 2011

An artificial body force method is presented to accurately simulate drawing processes in which back pressing is exerted. A rigid-plastic finite element method is applied together with a numerical scheme to eliminate the numerically incurred plastic deformation in rigid or elastic region, which significantly influences simulation results because it eventually changes reduction of area in drawing. Back tension or compression is applied by body force at the rear part of material to obtain numerically stable solution. Two typical examples are shown, a drawing process with back tension applied and a tube drawing with a fixed plug and back pressing applied.

• 소성∙가공
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• 제26권4호
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• pp.205-209
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• 2017

In this paper, finite element prediction of deformation of material due to springback after material removal by an axisymmetric forging fabrication at room temperature is conducted. An elastoplastic finite element method is employed considering die plastic deformation. The predictions of a springback analysis conducted after the final stroke of an axisymmetric cold forging process containing residual stresses are utilized to be mapped onto the final material after the material removal. It is assumed that material removal occurs at an instant, i.e., all the material to be removed disappears at once. The predictions are compared with experiments, revealing strong qualitative agreement.

• 한국정밀공학회지
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• 제18권2호
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• pp.72-78
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• 2001

Roundness measurement method using three displacement sensors makes in-process roundness measurement possible on the NC machine because it eliminates the vibration signal and eccentricity signal from measured roundness signal from the workpiece. But there are noises in measured signals, it isn't possible to measure the roundness with high precision. In this study, a high precision in-process roundness measurement system is development, which can eliminate vibrations of the spindle by using three displacement sensors and which can also estimate the noisy roundness measurement signals by applying Kalman filter.

• 디지털융복합연구
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• 제5권2호
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• pp.91-98
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• 2007

Destination marketing organizations (DMO) have been building up the cyber city in the WWW. Website for DMO is a core channel to promote regional attractions. This research suggests the issue of criteria for evaluating DMO's performance in the Internet. The method of evaluation focuses on the structure in perspective of linkage based on small world theory and direct network. Convention & Visitors & Bureau (CVB) in tourism and travel industry playa role to promote and held the international meeting and exhibitions. CVB's websites evaluated according to web link structure and performance.

• Journal of Information Display
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• 제8권2호
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• pp.1-4
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• 2007

IPS and VA have evolved in various structures such as H-IPS, AS-IPS, and S-PVA gain more competitiveness. The new pixel structures inherently have more domains which cause disclination areas. The effect of disclination is no longer neglected in those structures. A new simulation tool based on FAST Q-tensor method enables one to predict the shape of disclinations and the resulting optical properties. It ensures more accurate results compared to vector-based simulation. We applied this simulation tool for the development of 26-inch wide monitor having H-IPS mode.

• 한국데이타베이스학회:학술대회논문집
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• 한국데이타베이스학회 2008년도 연합학회학술대회
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• pp.477-486
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• 2008

This paper examines the evolution issues of regional tourism resources in complicated and networked industry the perspective of co-evolution types and dualism. Regional tourism structure has been changing more and faster according to various attractions and internal and external environment; natural resources, facilities, festivals and events, drama and movies, and public resources, etc. This paper approaches Olikowski's dualism perspective as a theoretical view about the alliance network between region's attractions and tourism industry in Korea. Exploratory analysis was explained the dualism cases performed on the matrix between resource characteristics and alliance complexity on human resources based on regional tourism industry.

• Journal of Information Technology Applications and Management
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• 제16권3호
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• pp.87-100
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• 2009

The purpose of this study is to investigate the evolution of regional tourism resources from the perspective of business ecosystem network. A regional tourism structure changes due to various factors such as natural resources, facilities, festivals and events, public resources, and etc. An exploratory analysis was conducted to examine the interaction between resource characteristics and alliance complexity in the regional tourism industry. In the process, the duality of technology provides an insight into the interaction among several players within an alliance network which include regional attractions and tourism industry. As a result. we identified four types of tourism alliance network: functional, organizational, resource-oriented, and artificially-allied. The managerial implications are also discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1187-1189
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• 1997

Currently, EMS(Energy Management System) database is implemented by relational concept but, It is hard to describe the characteristic of power system data which require real time management and composite type. This paper present the way how to design conceptual schema for EMS database using object-oriented concept which is free to describe composite data type and support inheritance concept.