• 한국분말재료학회지
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• 제26권5호
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• pp.369-374
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• 2019

The properties of powder metallurgy products are related to their densities. In the present work, we demonstrate a method to apply artificial neural networks (ANNs) trained on experimental data to predict the bulk density of barium titanates. The density is modeled as a function of pressure, press rate, heating rate, sintering temperature, and soaking time using the ANN method. The model predictions with the training and testing data result in a high coefficient of correlation (R2 = 0.95 and Pearson's r = 0.97) and low average error. Moreover, a graphical user interface for the model is developed on the basis of the transformed weights of the optimally trained model. It facilitates the prediction of an infinite combination of process parameters with reasonable accuracy. Sensitivity analysis performed on the ANN model aids the identification of the impact of process parameters on the density of barium titanates.

• 한국통신학회논문지
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• 제31권5B호
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• pp.405-412
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• 2006

게임 분야에서 온라인 게임은 높은 게임성과 안정적인 수익 모델로 인하여 많은 수가 개발되어 왔다. 특히, MMORPG는 게임의 특성상 많은 수의 사용자가 게임 서버에 접속하여 실시간으로 게임 서비스를 이용하게 된다. 따라서 게임 서버의 안정성은 매우 중요한 요소가 되므로 온라인 게임 개발 시에 장기간의 베타테스트를 통하여 게임 서버의 안정성을 실험하게 된다. 이러한 테스트는 많은 시간과 비용이 요구되는 과정이지만 반드시 필요한 과정이기도 하다. 본 논문은 온라인 게임의 서버를 테스트하기 위한 방법에 관한 것이다. 본 논문에서 제안된 시스템은 가상의 게임 클라이언트와 이들을 관리하는 에이전트를 이용하여 게임 서버를 자동으로 테스트할 수 있다. 제안된 방법을 온라인 게임 콘텐츠에 적용하여 다수의 동시 접속자 환경 하에서의 서버 성능 및 게임 관련 데이터를 효과적으로 모니터링 할 수 있음을 보였다.

• 유통과학연구
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• 제19권9호
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• pp.41-52
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• 2021

Purpose: Virtual reality is a unique technology to distribute data and demonstrates user's understanding towards complex products. The objective of this research is to investigate the impact of virtual reality on real world purchase intention of automotive cutting tools in Thailand's exhibitions. Hence, the research framework was constructed by telepresence, perception narrative, authenticity, trustworthiness, functional value, aesthetics, and purchase intention. Research design, data and methodology: Samples were collected from 500 visitors who participated in the selected top two metalworking exhibitions. Mix sampling approach is applied by using non-probability sampling methods of purposive or judgmental sampling, quota sampling, and convenience sampling method, respectively to reach target samples. Confirmatory Factor Analysis (CFA) and Structural Equation Model (SEM) were used to analyze and confirm goodness-of-fit of the model and hypothesis testing. Results: The results indicate that authenticity, functional value, and trustworthiness induced higher experiential value towards purchase intention. Those variables are stimulated by telepresence and perception narrative towards VR experience. Conclusions: Consumer's purchase intention towards VR experience on engineering cutting tools rely on consumer's sense of authenticity, trustworthiness, and functional value. Hence, marketing practitioners in automotive companies are encouraged to develop VR which focusing on significant factors to enhance consumers purchase intention.

• 정보처리학회논문지B
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• 제14B권6호
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• pp.407-412
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• 2007

초음파 의료 영상기기나 산업용 초음파 검사 시스템의 성능은 초음파 탐촉자의 성능에 의해 크게 좌우된다. 탐촉자의 성능 특성 정보는 보통 제작자가 제공하는 반사원의 초음파 R/F 신호와 주파수 특성에 의해 기술된다. 그러나 집속형 초음파 탐촉자의 경우, 두 자료로는 선명한 C-Scan 이미지를 얻을 수 있다는 것을 보증할 수는 없다. 그래서 집속형 초음파 탐촉자의 성능 평가를 위한 새로운 척도로 상대 초점크기 및 상대 유효초점영역의 모양을 제안한다. 상대 초점의 크기와 상대 유효초점영역의 모양은 쇠구슬로부터 획득된 초음파 R/F 신호를 가상 3차원 영상 복원 프로그램으로 처리하여 얻는다. 제시된 방법은 기존 자료로는 알 수 없었던 탐촉자 성능을 정확히 평가할 수 있었으며, 방법도 간단하여 실제 탐촉자 제작시 불/양품을 쉽게 가려 낼 수 있으며, 탐촉자 경년열화에 따른 성능 저하도 검출할 수 있는 장점을 갖는다. 결과적으로 초음파 영상기기나 산업용 초음파 검사 시스템의 성능을 담보할 수 있다.

• Steel and Composite Structures
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• 제9권3호
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• pp.223-237
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• 2009

The present research aims to develop a methodology to rapidly assess bridges with damage to the superstructure, caused by overheight trucks or lower-than-average overhead clearance. Terrestrial laser scanning and image processing techniques are combined with the finite element method to arrive at an analytical model which is more accurate, with respect to the complex geometrical aspects of the bridge in its damaged configuration. ""Virtual load testing"" may subsequently be carried out on this analytical model to determine the reserve capacity of the structure in an objective manner.

• 한국CDE학회논문집
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• 제12권1호
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• pp.15-26
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• 2007

We have developed a method that enables a user to better understand and enjoy the contents of 3D digital archives, thereby enhancing the user's experience. The system's interactive interface, built using virtual reality technology, enables the user to "walk through" the archives, comparing two or the same content at different points in time. For example, a user can compare the proposed design for a building with the actual building and can compare the states of restoration of a cultural heritage site over time. This ability to perform multilateral comparisons enables the user to clarify the relationship between contents, the influence of one content on another, and the causal relationship between contents. Testing of a prototype system for a 3D digital archive of cultural heritage sites showed that it worked smoothly and that the users could easily operate the navigation system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.229-238
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• 2009

In this paper, AWS ECU test method, which is considering behavior of a Bi-modal tram, is described. In order to evaluate the performance of an electronic automotive ECU, the method which combines HILS (Hardware In the Loop Simulation) and RBT (Requirement Based Testing) is introduced. HILS is the method to predict the behavior of a vehicle adopting an ECU. The behavior of a Bi-modal tram can be analyzed by using the vehicle dynamic model. Requirement Based Testing compare the outputs of a real system with a virtual electronic unit (oracle) which created by the requirements. Rear axles of the Bi-modal tram are independently controlled by two AWS ECU. Especially, swing out can happen when an articulated vehicle is operated in the curved road. Therefore dynamic behaviour of a Bi-modal tram is considered at this situation. Through this study, the reliability of ECU can be verified economically and safely using the proposed test method before conducting the track test.

• 한국정보과학회논문지:소프트웨어및응용
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• 제36권6호
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• pp.451-461
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• 2009

적응적 랜덤 테스팅(Adaptive Random Testing, ART)은 테스트 케이스의 효율적인 선택을 통해 순수 랜덤 테스팅(Random Testing, RT)보다 더 적은 수의 테스트 케이스를 이용해 입력 도메인 내의 오류를 찾는 것을 목적으로 한다. ART 기법 중 하나인 입력 도메인 반복 분할 기법(ART through Iterative Partitioning, IP-ART)은 초기 ART 기법의 단점인 많은 연산량을 입력 도메인 분할에 의해 효율적으로 개선되도록 하였으며, 입력 도메인 확장을 이용한 IP-ART(IP-ART with Enlarged Input Domain, EIP-ART)는 IP-ART의 테스트 케이스 분포 특징을 이용하여 추가적인 성능 향상과 확장성을 제공하였다. 하지만 EIP-ART는 입력 도메인 확장에 따라 발생하는 부하로 인해 테스트 케이스 생성에 오랜 시간을 요구하기 때문에 이의 개선이 필요하다. 따라서 본 논문에서는 두 가지의 추가 부하를 유발하지 않는 테스트 케이스 분포 조절 기법을 제안하고, 이들의 성능 개선 가능성을 실험을 통해 확인하였으며, 실험 결과, 제안된 두 기법 중 입력 도메인 타일링 기법이 모든 환경에서 더 우수한 성능 및 확장성을 갖는 것으로 확인되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.590-595
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• 2007

It is important to predict the collision behavior of a train consist to improve its crashworthiness. To analyze crash behavior of train, four kinds of methods are mainly used so far. The first is method using multibody dynamics to predict the gross motion of the train set. The second uses 3D FE model to apply the section analysis method in order. The third is used to deduce design specification and evaluate the crashworhiness of a train by using 1D model. The last is to constitute 2D model to check overriding and coupling devices. The train evaluation procedures are so complex that it is difficult to understand or deal with. In this study, VTM for railway train was introduced to simplify the procedures. VTM involves 3D models, 1D models and dynamic components such as suspension and coupling. The method using hybrid concept model makes it possible to do all the things that are mentioned above. To analyze crash behavior tendency of VTM, the model was simulated and the simulation results were discussed.

• 비파괴검사학회지
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• 제31권6호
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• pp.650-655
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• 2011

Analysis of two-dimensional Rayleigh wave scattering pattern by a surface defect is studied through modified boundary element method. BEM proposed in this paper has special treatment at each end of boundary which should have the Rayleigh wave go away without any generation of virtual reflections. It is shown that treatment for truncated boundary which is used to model two-dimensional Rayleigh waves' behavior in an elastic half-space is successfully implemented. To check numerical results' accuracy, time domain IFFT signal of the displacements is presented. Improvement on getting rid of unwanted influence of truncated boundary induced by 2-D Rayleigh waves on a flat surface of an elastic half-infinite medium is shown. As a final goal, the numerical results of Rayleigh wave scattering trend are plotted and they are compared with theoretical curves to prove its accuracy.