• The KIPS Transactions:PartB
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• v.16B no.6
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• pp.451-462
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• 2009

The spread of satellite image increases various services using it. Especially, 3D visualization services of the whole earth such as $Google\;Earth^{TM}$ and $Virtual\;Earth^{TM}$ or 3D GIS services for several cities provide realistic geometry information of buildings and terrain of wide areas. These service can be used in the various fields such as urban planning, improvement of roads, entertainment, military simulation and emergency response. The research about extracting the building and terrain information effectively from the high-resolution satellite image is required. In this paper, presents a system for effective extraction of the building model from a single high-resolution satellite image, after examine requirements for building model extraction. The proposed system utilizes geometric features of satellite image and the geometric relationship among the building, the shadow of the building, the positions of the sun and the satellite to minimize user interaction. Finally, after extracting the 3D building, the fact that effective extraction of the model from single high-resolution satellite will be show.

• Smart Media Journal
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• v.12 no.11
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• pp.113-124
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• 2023

With the advent of 5G and B5G (Beyond 5G) networks, network virtualization technology that can overcome the limitations of existing networks is attracting attention. The purpose of network virtualization is to provide solutions for efficient network resource utilization and various services. Existing heuristic-based VNE (Virtual Network Embedding) techniques have been studied, but the flexibility is limited. Therefore, in this paper, we propose a GNN-based network slicing classification scheme to meet various service requirements and a RL-based VNE scheme for optimal resource allocation. The proposed method performs optimal VNE using an Actor-Critic network. Finally, to evaluate the performance of the proposed technique, we compare it with Node Rank, MCST-VNE, and GCN-VNE techniques. Through performance analysis, it was shown that the GNN and RL-based VNE techniques are better than the existing techniques in terms of acceptance rate and resource efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.95-104
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• 2010

In wireless communication system, a variety of retransmission algorithms are used in order to improve the quality of service of users. But the system may be inefficient because retransmission algorithms operate independently with other layers. Also, the quality of service can be degraded due to the unnecessary retransmission of packets. To solve these problems, the study on the cross-layer retransmission schemes have been widely performed. However, in order to apply cross-layer retransmission schemes to wireless communication system, whether the performance of cross-layer retransmission schemes meets QoS requirements of each service class has to be verified. Thus, this paper proposes the mathematical model for analyzing the performance of the cross-layer retransmission schemes and derives both the suitable retransmission scheme and the optimal retransmission parameter on each service class. The proposed mathematical model selects the MCS level based on channel state information and The performance analysis is comparatively easy in case that HARQ, ARQ, and AMC schemes are combined. The proposed mathematical model also enables the analysis of the packet transmission delay. To utilize the analytical model, this paper derives the suitable retransmission scheme and the optimal retransmission parameter for delay sensitive services in WiMAX system. Also, the proposed analytical model can be used to analyze the performance of wireless communication system such as LTE and WLAN.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.508-516
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• 2006

The explosive growth of wireless network users and the existence of various wireless services have demanded high rate throughput as well as user's QoS guarantees. Towards this, this paper proposes QoS-oriented subcarrier allocation scheme considering the QoS provisioning of multiple users, which is major requirement for wireless network design point of view. This paper introduces joint RR/K&H combined with M-LWDF(Modified Largest Weighted Delay First) scheme throughout observing statistical channel behavior and real time queuing analysis for appropriate resource allocation tightly connected to multiuser scheduling. Accordingly, the system throughput can be enhanced, and the QoS demanded for delay sensitive services can be satisfied. Furthermore, the proposed scheme is applied for OFDMA(Orthogonal Frequency Division Multiple Access) systems to allocate sub-carriers in optimal way. The simulation results verify plausible performances of proposed resource allocation scheme via showing superior effective capacity under time-varying physical-layer channel behaviors.

• Journal of dental hygiene science
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• v.10 no.1
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• pp.55-61
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• 2010

The main purpose of this study was to identify the service quality of some dental clinics located in Gwangju and find an association between service quality and patient's intention to re-visit the same dental clinic. The search objects were 197 patients from five dental clinics, and data collected by self-administered questionnaire which was composed general characteristics, characteristics relating to visit of clinics, quality of service, patients satisfaction and intentions to re-visit. The used statistical analysis to find the association between quality of service and intention to re-visit was multiple regression analysis. This study looked at relations between quality of dental service, service satisfaction and intentions to visit again, and found that quality of service including six service areas had a statistically significant positive correlations with satisfaction and intentions of re-visit. When this study conducted a multiple regression analysis to identify variables that influence intentions of re-visit, it found that patients revisited the dental clinic only when quality of service was included. In conclusion, quality of service evaluated by patients influenced on their intention of re-visit and especially. Therefore, this study concludes that improvement in satisfaction and intentions of re-visit relies on Accessibility, that is, providing of medical information, consultant telephone, how delivery the dental medical system is. Service quality of dental institutes measured by SERVQUAL model and intention to re-visit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2801-2808
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• 2010

The technology of WiBro, combining advantages of high speed internet and wireless internet provides the effectiveness and convenience provided by broadband and convergence. WiBro has developed due to supports of the related industries. The advancement of WiBro have created driving force for network advancement. WiBro is a niche market among high speed Internet, wireless LAN, Mobile phone, wireless internet. Through building relationship between market share and the existed telecommunication service, WiBro could improve the convenience of users. The security controls have to be built considering vulnerabilities of WiBro. Based on the study, the architecture of WiBro was suggested through reviewing the vulnerabilities and security controls in the wireless network and wire network. The appropriate security measures to be applied in the environment of WiBro. The outcomes of the study could improve the usage of WiBro.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.21-31
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• 2018

In Hyper-Connected Society, IoT-based Lifelog data is used throughout the Internet and is an important component of customized services that reflect user requirements. Also, Users are using social network services to easily express their interests and feelings, and various life log data are being accumulated. In this paper, Intelligent characters using IoT based lifelog data have been developed and qualitative/quantitative data are collected and analyzed in order to systematically grasp emotions of users. For this, qualitative data through the social network service used by the user and quantitative data through the wearable device are collected. The collected data is verified for reliability by comparison with the persona through esnography. In the future, more intelligent characters will be developed to collect more user life log data to ensure data reliability and reduce errors in the analysis process to provide personalized services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5A
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• pp.738-744
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• 2001

멀티캐스팅이란 일대일의 전형적인 통신 모델과 one-to-all 방식의 브로드캐스팅의 중간적인 일대다 통신 모델이다. 여러 가지 통신 어플리케이션에서 멀티캐스팅 서비스를 제공하기 위해서는 많은 요구사항이 필요하며, 이를 위하여 여러 가지 멀티캐스팅 프로토콜이 연구되어 왔다. 그 중 신뢰도를 보장하기 위하여 논리적인 트리를 구성하고, 이러한 계층적 트리 기반의 복구 메커니즘을 이용하여 오류를 복구, 흐름 및 혼잡을 제어하는 방식이 Tree-based Multicasting Protocol이다. 본 논문에서는 Tree-based Multicasting Protocol에서 기본이 되는 논리적 트리를 구성하는데 있어 Top-down 방식을 따르는 프로토콜과 Bottom-up 방식을 따르는 프로토콜의 트리 구성 방식을 살펴보고, 시뮬레이션을 통하여 멀티캐스팅 그룹에 참여하는 노드수가 증가함에 따라 트리 구성시 교환되는 메시지 수와 트리 구성 지연 시간, 트리 Depth 등을 비교하였다.

• Electronics and Telecommunications Trends
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• v.24 no.3
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• pp.1-12
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• 2009

30여 년 전에 연구망으로서 개발이 시작된 인터넷은 현재 사회의 공공 인프라로서의 역할로 기능이 확장되면서 이동성, QoS 지원, 보안성 등을 고려한 점진적 개선이 이루어져 왔다. 그러나, 이러한 점진적 개선 방법의 한계성 때문에 현재의 인터넷 구조가 향후 $20{\sim}30$년 후의 미래사회의 인프라로서도 적합할 것인가에 대한 의구심이 생기기 시작하였다. 이에 따라, 기존 인터넷과의 호환성을 고려하지 않고, 처음부터 현재 및 미래서비스의 요구사항에 기반하여 네트워크를 새로 설계하고자 하는 "미래인터넷" 연구가 시작되었다. 미래인터넷에 대한 연구는 아직 초기단계로서, 거시적 목표를 위해 다양한 네트워크 아키텍처들이 제시되고 있는데, 본 고에서는 미래인터넷의 등장 배경과 지향점, 각국의 연구 현황을 살펴보고, 미래인터넷 아키텍처에 대한 연구자들의 다양한 아이디어를 주요 이슈별로 소개하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.442-445
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• 2011

본 연구에서는 슈퍼컴퓨터를 이용하여 분산 임베디드 시스템의 대표적인 응용인 센서네트워크 시스템 연구/개발에 사용할 수 있는 병렬 센서 네트워크 시뮬레이터에 관하여 연구를 수행하였다. 현재 센서네트워크 개발자들이 많이 사용하는 Avrora 라는 분산 시뮬레이터를 슈퍼컴퓨터에 적재하여 시뮬레이션 성능을 분석하고, 슈퍼컴퓨터를 이용하여 시뮬레이션 속도가 개선되는지를 확인하였으며, 이를 바탕으로 향후 이러한 분산 임베디드 시스템의 시뮬레이션 서비스를 제공하기 위해 개선되어야 하는 소프트웨어 및 시스템적 요구사항을 도출하였다.