• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.68-71
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• 2001

Integrated Simulation System of Aircraft is a networked virtual synthetic environment. This paper presents hardware-in-the-loop simulation, man-in-the-loop simulation, computer generated aircraft, virtual prototype of aircraft dynamics, and networked simulation system.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.1168-1174
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• 2006

본 논문에서는 실감형 Networked Virtual Environment (NVE)의 사실성 증진을 위한 Non Player Character (NPC)의 지능적 제어 프레임워크를 제안한다. 이 프레임워크는 반응의 다양성, 실시간성 그리고 NPC의 능동성면에서 기존 게임에서 사용되는 NPC 구현 기법과 차이가 있다. 기존 NPC 제어구조의 경우, 휴먼 사용자의 행동에 따른 NPC의 반응이 일정 스크립트나 규칙에 따르기 때문에 정형적이며, 또한 NPC의 반응시간에 대한 실시간성을 고려하지 않고 있다. 또한 NPC는 휴먼 사용자의 액션에 반응하는 종속적이고 수동적인 역할만을 담당한다. 제안하는 프레임워크에서는 NPC는 각자의 취향을 가지고 있어 다양한 반응과 행동양식을 보일 수 있으며, NPC의 행동 결정 시간에 어느 정도 실시간성을 부여할 수 있으며, 또한 NPC의 역할이 수동적 형태에서 벗어나 능동적으로 계획하여 행동을 실행할 수 있다. 프레임워크의 구현을 위해 SWI-Prolog의 Rule based 추론엔진과 유전자 알고리즘을 사용하였다.

• Journal of Information Processing Systems
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• v.9 no.3
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• pp.489-498
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• 2013

In this paper, we propose a common simulation model that can be reused for different performance evaluations of networked virtual environments. To this end, we analyzed the common features of NVEs, in which multiple regions compose a shared space, and where a user has his/her own interest area. Communication architecture can be client-server or peer-server models. In usual simulations, users move around the world while the number of users varies with the system. Our model provides various simulation parameters to customize the region configuration and user movement pattern. Furthermore, our model introduces a way to mimic a lot of users in a minimal experiment environment. The proposed model is integrated with our network framework, which supports various scalability approaches. We specifically applied our model to the interest management and load distribution schemes to evaluate communication overhead. With the proposed simulation model, a new simulation can be easily designed in a large-scale environment.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.189-192
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• 2000

This paper presents a new DR(Dead Reckoning) algorithm in client-server-based networked virtual environment using network delay estimation. In the algorithm, a new update packet is sent to server (or client) whenever the difference of current real value and tracking value after network delay is larger than threshold. To confirm the proposed algorithm, a test network game was implemented. Through iterative field tests, we knew that this algorithm provides fair service and stability.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.247-249
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• 2000

네트워크 인프라와 개인 PC 의 성능 향상으로, 실세계와 흡사한 가상세계가 점차 활성화되는 추세이다. 네트워크에 기반한 가상 환경이 갖는 가장 큰 장점은, 물리적으로 멀리 떨어져 있는 여러 사용자들을 하나의 가상공간에 있는 듯한 착각(illusion)을 주고, 실시간으로 상호작용이 가능하다는 것이다. 본 논문에서는 이러한 networked Virtual Environment(이하 net- VE)의 구성에 고려되어 지는 네트워크 구조와 DIS, HLA, vrtp등의 프로토콜을 살펴보고, 기존의 군사용 그리고 대학에서 구성된 net-VE 환경들에 대한 일반적인 특성들을 정리해본다. 그리고 현재 국내에서 서비스 되고 있는 net-VE 환경을 살펴본다.

• Journal of the Korea Computer Graphics Society
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• v.2 no.2
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• pp.37-44
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• 1996

Networked virtual reality systems provide a consistent virtual world to the users, possibly distributed across long distances, and have been widely applied in the military, entertainment, and architectural areas. Large processing requirements, however, made these systems be mainly researched on the platforms of high-performance graphics workstations. This paper presents several problems when networked virtual reality systems are implemented on commodity PCs: two problems related with 3D graphical processing, and the other related with network bandwidth and transmission delay. We also suggest solutions to these problems and analyze their performance effect based on an architectural simulation application.

• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.208-214
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• 2006

Participants of a NVE(networked virtual environment) may have different hardwares and network environments, and to guarantee the fairness, messages of participants should be synchronized. A solution for the synchronization problem is to wait for a certain amount of time until the server processes the message. It is not easy to determine a suitable waiting period because of the trade-off between the fairness and the responsiveness. In this paper we propose a method to decide a waiting period by considering only the participants with small network delays and perform experiments for the performance evaluation. Experiments show that the proposed method leads to significant improvement of responsiveness, while retaining fairness.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.7
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• pp.646-656
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• 2008

In this paper, the prototype of haptic-based NVE (networked virtual environment) QoE (quality of experience) is proposed. The proposed framework plays a role of providing users with realistic feeling by managing the system and network resources efficiently under time-varying networks and heterogeneous systems. Therefore, first IoPH (importance of presence for haptic interaction) is defined to quantitate the sense of real that the users feel now. Then we define the haptic-based NVE components required to satisfy the haptic interaction QoE requirements. Finally, QoE adaptation scheme is suggested, which adapts the haptic-based NVE components to current network and system constraints for better haptic interaction quality.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.59-64
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• 2008

In this paper, stability and transparency analysis for client/server haptic-based networked virtual environment (NVE) is introduced. From this analysis the appropriate communication structure for the more stable and transparent haptic interactions can be derived. Also, it is possible to expect and compensate the quality deterioration of haptic interactions according to certain network conditions In order to verify the usefulness of the analysis, simple haptic-based NVE application is implemented. For the stability verification, the vibration or strange movement of haptic interface and virtual object are measured under various network states. In addition, the usefulness of the proposed transparency analysis and network delay compensation scheme is verified by comparing distorted and compensated force feedbacks with real force feedback.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.829-832
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• 2004

대단위(large-scale) 가상현실 시스템이나 가상현실 시스템의 구성요소가 네트워크(일반적인 통신망)를 통하여 분산되어 있는 경우를 네트워크 가상현실 시스템(Net-VE : Networked Virtual Environment)이라 한다. 가상현실의 환경을 분산 처리하는 경우 가상현실 시각의 공유방법, 분산시스템의 구성방법, 저속 혹은 고속통신망을 통한 대량의 데이터를 전송하는 방법, 가상현실 내의 이용자의 상호작용 방법, 데이터 공유방법, 분산처리 방법 등 가상현실 기술에 부가하여 통신망기술, 프로토콜 공학, 분산 처리기술 등 다양한 주변 기술이 필요하다. 따라서 본 논문에서는 더 유연성 있고 모듈러한 네트워크 가상 환경을 구축하는데 있어 효율적인 객체 지향 프로그래밍 기술인 자바의 다중 쓰레드 병렬처리 기법을 사용하고자 한다. 자바의 쓰레드 구조를 사용함으로써 네트워크 가상환경에서 여러 클라이언트에서 요청하는 데이터를 네트워크를 통한 지연에 대한 효과적인 대안으로서 자바의 다중 쓰레드 병렬처리 기법을 제안하고자 한다.