• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.44-53
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• 2004

RFID 시스템에서는 리더가 다수의 태그를 읽는 다중접속방식(Multi-access Mode)을 이용하므로 태그간 충돌이 발생한다. 또한 넓은 면적에서 다수의 리더가 태그를 읽을 때에는 리더간의 충돌도 발생한다. 이러한 충돌은 RFID 시스템의 효율에 큰 영향을 미치므로, 효과적인 충돌방지 알고리즘이 요구된다. 현재 RFID의 충돌방지 알고리듬은 REID 시스템의 효율과 직결되기 때문에 공개를 꺼리고 있어 많은 자료를 구할 수는 없으나, 본고는 RFID 시스템의 다중인식 기술 및 태그의 충동방지 알고리즘 그리고 리더의 충돌방지 알고리즘 중 널리 알려진 것을 소개한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.373-380
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• 2018

We present the peridynamic dynamic fracture analysis to solve impact fracturing of multilayered glass impacted by a high-velocity object. In the most practical multilayered glass structures, main layers are glued by thin elastic masking films. Thus, it is difficult and expensive to construct the numerical model for such a multilayered structure. In this paper, we employ efficient numerical modeling of multilayered structures with a nonlocal ghost interlayer model in which ghost particles are distributed between main layers and they are interacting with each other in peridynamic way. We also consider a simple nonlocal contact condition in peridynamic frameworks to solve impact and penetration of the high-velocity impactor to the multilayered structure. Finally we can confirm the fracture capabilities of the method using a multilayered glass model in which 7 glass layers and a single elastic backing layer are affixed by polyvinyl butyral films.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.197-203
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• 2012

In this paper, study the substantial issues which occurs upon free flight environment by performing separation assurance under multiple conflict(over 3 Aircraft), recovery en route under the terms of time constrains and fixed way point after the conflict avoidance, correlations between conflict detection distance and separation assurance by utilizing Autonomous flight algorithm. Result of this experiment demonstrates that the extension of detection distance is advantageous to solution of separation assurance and enhancing of flight efficiency, choose to maneuver by applying time constrain terms and fixed way point according to the situation of conflict prediction in case of recovery maneuver after the conflict avoidance. And separation assurance can be solved by applying 2 degrees or more of bank angle. When choosing the optimal bank angle could be drastically improved flight efficiency.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.2
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• pp.143-148
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• 2005

In this paper, we introduce smart home service based on ubiquitous environment and context awareness. We define the multi- context environment and the context collision caused by many user that the existing study of smart home is unconcerned with. Heal home is the space where various contexts are created and disappeared in. Smart home appliances are restricted within their service. We divide the home space by main uses of rooms and group smart service by sensory organ. And we introduce the multi-context manager consist with context interpreter, context collision manager and smart service manager.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.125-135
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• 2012

The FE model for shot peening often assume that shots impact vertically on the engineering parts to generate compressive residual stresses. However, the shots obliquely impact on the surface in actual peening. In this work, we propose a 3D finite element (FE) model for evaluation of residual stress under angled shot peening. Using the FE model for angled multi-impact, we examine the effects of factors such as impact angle, impact pattern and the number of shots. Plastic deformation of shot is also considered. To validate the model, we then compare the FE solution with experimental result by X-ray diffraction (XRD). The proposed model will be a base of 3D multi-impact FE model with diverse impact angles.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1130-1137
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• 2006

One of the important performance issues in large-scale RFID systems is to resolve collisions among responses from RFID tags. Considering two do facto anti-collision solutions, namely the binary-tree splitting algorithm and the Slotted-Aloha algorithm, we propose to use multi-packet reception (MPR) capability to enhance the RFID tag reading rate (i.e., throughput). MPR allows an RFID reader to receive multiple reponses transmitted by tags at the same time. We analyze the effect of MPR capability in the above anti-collision algorithms, which is also validated by simulation. The analysis and simulation results show that RFID reader antenna design and signal separation techniques play an important role in improving RFID system performance with MPR capability.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.916-918
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• 2004

본 논문에서는 3D 게임에서 다중 캐릭터의 충돌 회피에 대한 방법을 제안한다. 캐릭터는 충돌 감지 서클을 이동 상태 정보와 결합하여 다른 캐릭터와의 충돌을 예측하여, 충돌이 예측될 경우 충돌을 발생시킨 캐릭터들에 대해 초기화시에 설정된 레벨을 참고하여 충돌을 발생시키지 않는 정점을 목표지점과의 거리자를 이용하여 탐색하고 캐릭터를 이동한다. 이동한 지점은 캐릭터의 목표지정과 충돌을 발생시키지 않으며 최단 거리를 보장할 수 있는 위치이고, 이동된 지정에서 목표지정까지는 A* search를 이용하여 Pathfinding을 수행한다. 본 논문에서 제안한 방범을 적용함으로써 3D 게임에서 캐릭터와의 충돌을 회피하면서 목표지정까지 최단거리를 보장받을 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.69-71
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• 1998

다중 데이터베이스 시스템에서 전역 트랜잭션을 순차적으로 실행하여도 전역 직렬가능성 보장을 위한 동시성 제어 방법의 개발에서 가장 중요한 고려 요소가 되는 간접충돌은 발생한다. 본 논문에서는, 간접충돌과 전역 직렬가능성의 관계를 분석하여 순차실행은 전역 직렬가능성에 영향을 주지 않음을 보였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.323-331
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• 2010

In this study, we propose a 3D finite element (FE) model for the residual stress under oblique shot peening. Using the FE model for an oblique impact, we examine the effects of factors on the residual stress such as the Rayleigh damping in the material, dynamic friction, and the rate dependency of the material and systematically integrate the effects. The plastic deformation of the shot is also emphasized. Then, the FE model is used to study oblique multi-impacts. The results obtained using the FE model are compared with experimental x-ray diffraction (XRD) results; in contrast to the rigid and elastic shots, plastic shots are found to produce residual stresses similar to that shown in the XRD results. Thus, the 3D FE models with integrated factors and plastically deformable shots are validated. The proposed model will serve as a basis for the 3D FE model for multi-impacts with different impact angles to simulate the actual phenomenon of shot peening.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.139-141
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• 2016

본 논문에서는 실시간 실내 다중 이동 로봇 충돌 회피에 관한 연구이다. 충돌 회피 기법에는 센서를 이용한 포텐셜 필드 기법 등 다양한 방법[1,2,3]이 있지만 좁은 실내 공간에서 사용하기에는 제한점이 많다. 본 논문에서 제안하는 시스템은 서버, 감시카메라, 로봇 세 가지로 구성되어 있으며 여러 모듈간 상호작용을 통한 충돌 회피 시스템을 제안한다. 감시카메라는 서버에게 실시간으로 영상을 제공해 실내 상황을 파악하게 한다. 서버는 실내 공간에 있는 모든 로봇을 관리하고 감시카메라로부터 받은 영상을 이용한 맵 매칭을 통해 로봇의 위치를 파악한다. 그다음 로봇의 위치를 토대로 경로를 생성하여 로봇에게 전송한다. 로봇 또한 서버에게 경로, 속도를 전송 받아 목적지로 이동하며 서버로부터 지속적인 관리를 받아 충돌을 방지해 목적지까지 신속하고 정확하게 이동하는 것이 본 논문의 목적이다.