• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.83-87
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• 2007

This research studies real time interaction and dynamic data shared through 3D scenes in virtual network environments. In a distributed virtual environment of client-server structure, consistency is maintained by the static information exchange; as jerks occur by packet delay when updating messages of dynamic data exchanges are broadcasted disorderly, the network bottleneck is reduced by predicting the movement path by using the Dead-reckoning algorithm. In Dead-reckoning path prediction, the error between the estimated and the actual static values which is over the threshold based on the shared object location requires interpolation and multicasting of the previous location by the ESPDU of DIS. The shared dynamic data of the 3D virtual environment is implementation using the VRML.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.848-849
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• 2012

본 논문에서는 운전자가 후진 시, 자동차의 후진 예상경로를 파악하여 내비게이션이나 휴대용 기기에 후방카메라 영상과 예상 경로를 함께 표시하여 안전운전을 도와주는 경로 예측 방식의 후진 주차 가이드 시스템을 개발하였다. 본 시스템은 다양한 차종에 적용 가능하며, 다양한 후방카메라의 특성 및 설치환경을 지원하고 내비게이션이나 휴대용 기기에 호환되며 시스템의 탈부착이 쉽고, 편리하게 구성할 수 있다.

• 전자공학회논문지S
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• 제34S권11호
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• pp.1-8
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• 1997

A prediction model is proposed to describe the path loss in propagation environment of indoor microcell. This model includes the lineal corridor for line--of-sight(LOS) and T-shaped corridor for non-line-of-sight(NLOS). In computation of receiving power the ray tracing technique based on image method is utilized and also reflected waves bounced on the walls and ceilings are considered. To check validity of the computed resuls cross checks between the predicted and measured are being made, which shows a close agreement for LOS case whereas somewhat disagreement for NLOS case. UTD technique is incorporated with propagation path determination algorithm in the treatment of NLOS case.

• 한국지능시스템학회논문지
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• 제19권5호
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• pp.655-660
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• 2009

기존의 예측 알고리즘들은 실시간 환경에서 학습 데이터 처리에서 오는 시간지연 문제, 구현의 어려움 등으로 개인화된 실시간 서비스를 제공하는 컨텍스트 인식 환경에서 사용하기에 적합하지 않다. 본 논문에서는 사용자 모델을 이용하여 컨텍스트 예측 알고리즘의 처리시간 단축과 예측 정확도를 향상시키기 위한 연구를 제안한다. 컨텍스트 예측을 위하여 사용자의 컨텍스트 중에서 이동경로를 사용한다. 이동경로를 기반으로 시계열 분석 방법을 통하여 사용자 모델을 생성하고, 생성된 사용자 모델을 시퀀스 매칭 방법을 이용하여 사용자의 컨텍스트를 예측한다. 기존 예측 알고리즘과 본 연구에서 제안한 예측 알고리즘을 시뮬레이션을 통하여 처리시간 및 예측 정확도를 비교한 결과, 실시간 서비스 환경에서 예측 정확도는 기존 예측 알고리즘들과 비슷한 결과를 보였고, 처리시간은 사용자 모델을 사용한 경우가 시퀀스 매칭을 사용한 경우보다 평균 40% 정도 감소시킬 수 있음을 알 수 있었다.

• 대한기계학회논문집
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• 제17권8호
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• pp.2012-2022
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• 1993

For the machining of the sculptured surfaces on 5-axis CNC milling machine, the milling cutter direction vector was determined in the study (I) with 5-axis post-processing. Thus, it was possible to cut the sculptured surfaces on five-axis CNC milling machine with the end mill cutter. Then, for smooth machined surfaces in five-axis machining of free-from surfaces, this study develops an algorithm for prediction of cusp heights. Also, it generates tool path such that the cusp heights are constrained to a constant value or under a certain value. For prediction of the cusp height between two basis points, a common plane, containing the line crossing two basis points and the summation vector of two normal vectors at two basis points, is defined. The cusp height is the maximum value of scallops on the common plane after end mill cutter passes through the common plane. Sculptured surfaces were machined with CINCINNATI MILACRON 5-axis machining center, model 20V-80, using end mill cutter. Cusp heights were verified by 3-dimensional measuring machine with laser scanner, WEGU Messtechnik GmbH.

• 한국통신학회논문지
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• 제30권7A호
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• pp.550-556
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• 2005

본 논문은 철도와 같은 이동 네트워크 환경에서 핸드오버로 인한 서비스 중단 시간 및 패킷 손실을 최소화하기 위하여 이동경로 예측 기반의 끊김없는 핸드오버 방안을 제안한다. 정해진 경로를 따라 이동하는 철도차량의 고유한 특징을 이용하여, 2계층 핸드오버를 수행하기 전에 미리 3 계층 핸드오버를 수행함으로써 핸드오버로 인한 서비스 단절과 패킷 손실을 최소화 시킬 수 있다. 성능평가 결과 제안된 방안은 기존 NEMO 방안에 비해 핸드오버 수행에 있어 우수한 성능을 나타냄을 알 수 있었다.

• Journal of Information Technology Applications and Management
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• 제20권4호
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• pp.191-205
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• 2013

Recently, the topic of predicting interpersonal trust in online social networks is receiving considerable attention, because trust plays a critical role in controlling the spread of distorted information and vicious rumors, as well as reducing uncertainties and risk from unreliable users in social networks. Several trust prediction models have been developed on the basis of transitivity and composability properties of trust; however, it is hard to find empirical studies on whether and how transitivity and composability properties of trust are operated in real online social networks. This study aims to predict interpersonal trust between two unknown users in social networks and verify the proposition on whether and how transitivity and composability of trust are operated in social networks. For this purpose, we chose three social network sites called FilmTrust, Advogato, and Epinion, which contain explicit trust information by their users, and we empirically investigated the proposition. Experimental results showed that trust can be propagated farther and farther along the trust link; however, when path distance becomes distant, the accuracy of trust prediction lowers because noise is activated in the process of trust propagation. Also, the composability property of trust is operated as we expected in real social networks. However, contrary to our expectations, when the path is synthesized more during the trust prediction, the reliability of predicted trust did not tend to increase gradually.

• 한국통신학회논문지
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• 제33권5A호
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• pp.536-541
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• 2008

우리에게 다가온 4G 차세대 이동통신 시스템은 유 무선 네트워크의 통합과 더불어 이동성의 증가와 고속 데이터 전송(음성 및 멀티미디어 데이터)을 제공하는 형태로 진화해 나갈 것이다. 여기에서 이동성 지원의 가장 핵심이 될 수 있는 것은 바로 이동하고 있는 단말의 경로 예측이며, 실제로 무선망이 처음 소개되면서 이에 대한 연구가 활발히 있었으나 실제 이동 환경에 적용하기에는 위험부담이 크기 때문에 적용하기가 쉽지 않았다. 본 논문에서는 이러한 문제를 고려하여 기존의 이동성 예측 알고리즘을 기반으로 Signaling Power Level 비교 및 Speed 기반의 예측 기법을 도입하여 실제 환경에 최적화 되어진 예측 알고리즘을 제안하였다. 그리고 기존 예측 알고리즘과 제안하고 있는 예측 알고리즘을 OPNet 시뮬레이션을 통해 비교하여 보았다.

• 소성∙가공
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• 제14권6호
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• pp.527-532
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• 2005

Among the failure modes which can occur in tube hydroforming such as wrinkling, bursting or buckling, the bursting by local instability under excessive tensile stresses is irrecoverable phenomenon. Thus, the accurate prediction of bursting condition plays an important role in producing the successfully hydroformed part without any defects. As the classical forming limit criteria, strain-based forming limit diagram (FLD) has widely used to predict the failure in sheet metal forming. However, it is known that the FLD is extremely dependant on strain path throughout the forming process. Furthermore, The application of FLD to hydroforming process, where strain path is no longer linear throughout forming process, may lead to misunderstanding for fracture initiation. In this work, stress-based forming limit diagram (FLSD), which is strain path-independent and more general, was applied to prediction of forming limit in tube hydroforming. Combined with the analytical FLSD determined from plastic instability theory, finite element analyses were carried out to find out the state of stresses during hydroforming operation, and then FLSD is utilized as forming limit criterion. In addition, the approach is verified by a series of bulge tests in view of bursting pressure and shows a good agreement. Consequently, it is shown that the approach proposed in this paper will provide a feasible method to satisfy the increasing practical demands for judging the forming severity in hydroforming processes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.122-125
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• 2005

This study is an measurement and prediction of transmission loss through dash panel with multi-path in a vehicle. Measurement results of transmission loss are derided by sound power measured using the sound intensity method under locating a sound source in the anechoic room and reverberant room, respectively. Prediction one is decided by multi-path analysis of dash panel composed by a various part of materials and complicated shape. Finally, two results show a great agreement between measured and predicted transmission loss.