차별화 서비스망을 위한 정책 기반 서비스 품질 관리 모델

차시호,강영만,조국현,Cha, Si-Ho,Kang, Young-Man,Cho, Kuk-Hyun 한국정보처리학회 2003 정보처리학회논문지 C : 정보통신,정보보안 Vol.10 No.2

차별화 서비스(DiffServ)는 효율적이며 규모성을 갖는 방법으로 서비스 품질(QoS)을 제공하는 기술이다. 그러나, 현재의 차별화 서비스 규격들은 완전한 QoS 관리 프레임워크와 구현 모델의 제공에는 취약한 실정이다. 본 논문은 차별화 서비스 망의 QoS를 관리하기 위하여 차별화 서비스 정책을 지원하는 정책 기반 차별화 서비스 QoS 관리 모델을 제안한다. 이 모델을 모델-뷰-컨트롤러(MVC) 구조를 따르며, EJB(Enterprise JavaBeans) 기술에 기반을 두고 있다. 우리의 모델에서 상위 레벨 차별화 서비스 QoS 정책들은 XML 스키마를 갖는 유효한 XML 문서들로 표현되고 EJB 기반 정책 서버 내에 하위 레벨 EJB 정책 번들로 변환된다. QoS 정책을 정의하기 위해 필요한 라우팅 형상과 라우터의 역할 정보 검출은 SNMP MIB-II를 사용하고, QoS 정책 분배와 모니터링은 SNMP DiffServ MIB를 사용한다. Differentiated Services (DiffServ) is a technique to provide Quality of Service (QoS) in an efficient and scalable way. However, current DiffServ specifications have limitations in providing the complete QoS management framework and its implementation model. This paper proposes a policy-based QoS management model that supports DiffServ policies for managing QoS of DiffServ networks. The management model conforms to Model-View-Controller (MVC) architecture, and is based on Enterprise JavaBeans (EJBs) technologies. In our model, high-level DiffServ QoS policies are represented as valid XML documents with an XML Schema and are translated to low-level EJB policy beans in the EJB-based policy server. The routing topology and role information required to define QoS policies is discovered by using SNMP MIB-II, and the QoS policy distribution and monitoring is accomplished by using SNMP DiffServ MIB.

RFID와 적외선 센서를 이용한 OSGi 기반 홈 헬스케어 시스템의 설계 및 구현

차시호,김대영,최재호,이종언,조국현,김규호 한국통신학회 2008 韓國通信學會論文誌 Vol.28 No.8A

네트워크 기반 시설의 확충과 관련 기술의 발전으로 홈 네트워크 시장은 점점 더 확대되어 가고 있지만, 홈 네트워크 분야 중 헬스케어 분야는 다른 분야에 비해 느린 성장을 보이고 있다. 전 세계적으로 노령 인구가 급속하게 증가함에 따라 그 어느 분야보다 실버케어 분야의 필요성이 증대되고 있다. 본 논문에서는 보호자가 피보호자의 상태를 쉽게 모니터링 할 수 있고, 위급 상황을 보호자 및 의료 기관에 통보 할 수 있는 홈 헬스케어 시스템을 설계하고 구현한다. 제안된 홈 헬스케어 시스템은 고령층의 하루 활동량 등의 분석을 위해 RFID와 적외선 센서 등을 활용하였으며, 홈 게이트웨이 미들웨어 표준인 OSGi를 이용해 다양한 이기종 장비들을 쉽게 통합할 수 있도록 하였다.

차등 서비스를 위한 EJB 기반 QoS 관리 시스템 프레임워크의 설계 및 구현

차시호,이종언,안병호,조국현,Cha Si ho,Lee Jong eon,Ahn Byung ho,Cho Kuk hyun 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.4B

차등 서비스 모델은 개별적인 플로우들 보다는 집합적인 트래픽 클래스들을 지원하므로 IP 망 내의 다양한 패킷 클래스들에 대하여 다양한 QoS를 제공할 수 있다. 그럼에도 불구하고, 차등 서비스 모델은 완전한 QoS 관리 프레임워크와 그의 구현 모델을 제공하지는 못한다. 차등 서비스 망에서의 QoS 보장 서비스를 제공하기 위해서는 망 및 서비스 관리의 지원이 필수적으로 필요하다. 따라서, 본 논문은 차등 서비스를 지원하기 위하여 EJB 기반 QoS 관리 시스템을 제안하고 구현한다. 구현되는 QoS 관리 시스템은 상위 레벨 QoS 정책들은 유효한 XML 문서로 표현되며 하위 레벨 QoS 정책들인 EJB 기반 정책 서버 내의 EJB 빈들로 사상된다. 하위 레벨 QoS 정책들은 SNMP 차등 서비스 MIB를 통해 차등 서비스 라우터들로 분배되고 감시된다. DiffServ supports aggregated traffic classes to provide various QoS to different classes of traffics. However, current DiffServ specifications do not have a complete QoS management framework. It is possible to lead to serious QoS violations without a QoS management support. From this reasoning, a QoS management system that can manage differentiated QoS provisioning is required. This paper proposes and implements a policy-based QoS management platform for differentiated services networks, which specifies QoS policies to guarantee dynamic QoS requirements. The implementation of the proposed platform is built on W framework and uses XML to represent and validate high-level QoS policies. High-level QoS policies are represented as valid XML documents and are mapped into Em beans of the EJB-based policy server of the platform. The policy distribution and the QoS monitoring are processed using SNMP.

멀티 라디오 멀티 채널 무선 메쉬 네트워크를 위한 클러스터 기반 최소 간섭 채널 할당

차시호,류민우,조국현 (사)디지털산업정보학회 2010 디지털산업정보학회논문지 Vol.6 No.3

Total performance is improved by minimizing the channel interference between links in wireless mesh networks (WMNs). The paper refines on the CB-CA [1] to be suitable for multi-radio multi-channel (MRMC) WMNs. The CB-CA is the cluster-based channel assignment algorithm for one radio three channel WMN based on IEEE 802.11b/g. The CB-CA does not perform the channel scanning and the channel switching between the cluster heads (CHs) and the edge gateway nodes (EGs). However, the use of co-channel for links between CHs and EGs brings the problem of channel interference among many nodes. We propose and evaluate an improved CB-CA algorithm to solve this problem in MRMC WMNs. The proposed algorithm discriminates between transmission channel and receive channel and assigns channels to each interface randomly and advertises this information to neighbor clusters in order to be assigned no-interference channel between clusters. Therefore, the proposed algorithm can minimize the interference between clusters and also improve QoS, since it can use multiple interfaces and multiple channels.

차량의 이동 방향과 거리 기반의 그리디 애니캐스트 포워딩 프로토콜

차시호,이종언,류민우,Cha, Siho,Lee, Jongeon,Ryu, Minwoo 디지털산업정보학회 2017 디지털산업정보학회논문지 Vol.13 No.1

Vehicular ad-hoc networks (VANETs) cause link disconnection problems due to the rapid speed and the frequent moving direction change of vehicles. Link disconnection in vehicle-to-vehicle communication is an important issue that must be solved because it decreases the reliability of packet forwarding. From the characteristics of VANETs, greedy forwarding protocols using the position information based on the inter-vehicle distance have gained attention. However, greedy forwarding protocols do not perform well in the urban environment where the direction of the vehicle changes greatly. It is because greedy forwarding protocols select the neighbor vehicle that is closest to the destination vehicle as the next transmission vehicle. In this paper, we propose a greedy anycast forwarding (GAF) protocol to improve the reliability of the inter-vehicle communication. The proposed GAF protocol combines the greedy forwarding scheme and the anycast forwarding method. Simulation results show that the GAF protocol can provide a better packet delivery rate than existing greedy forwarding protocols.

서비스 오케스트레이션 기반 사용자 맞춤형 IoT 서비스의 설계 및 구현

차시호,류민우,Cha, Siho,Ryu, Minwoo 디지털산업정보학회 2015 디지털산업정보학회논문지 Vol.11 No.3

The Internet of Things (IoT) is an Infrastructure which allows to connect with each device in physical world through the Internet. Thus IoT enables to provide meahup services or intelligent services to human user using collected data from those devices. Due to these advantages, IoT is used in divers service domains such as traffic, distribution, healthcare, and smart city. However, current IoT provides restricted services because it only supports monitor and control devices according to collected data from the devices. To resolve this problem, we propose a design and implementation of personalized IoT service base on service orchestration. The proposed service allows to discover specific services and then to combine the services according to a user location. To this end, we develop a service ontology to interpret user information according to meanings and smartphone web app to use the IoT service by human user. We also develop a service platform to work with external IoT platform. Finally, to show feasibility, we evaluate the proposed system via study.

교차로에서 원활한 교통 흐름 지원을 위한 VANET 기반 동적인 교통 신호등 제어 기법

차시호,이종언,류민우 (사)디지털산업정보학회 2022 디지털산업정보학회논문지 Vol.18 No.4

Recently, traffic congestion and environmental pollution have occurred due to population concentration and vehicle increase in large cities. Various studies are being conducted to solve these problems. Most of the traffic congestion in cities is caused by traffic signals at intersections. This paper proposes a dynamic traffic light control (DTLC) scheme to support safe vehicle operation and smooth traffic flow using real-time traffic information based on VANET. DTLC receives instantaneous speed and directional information of each vehicle through road side units (RSUs) to obtain the density and average speed of vehicles for each direction. RSUs deliver this information to traffic light controllers (TLCs), which utilize it to dynamically control traffic lights at intersections. To demonstrate the validity of DTLC, simulations were performed on average driving speed and average waiting time using the ns-2 simulator. Simulation results show that DTLC can provide smooth traffic flow by increasing average driving speed at dense intersections and reducing average waiting time.

한국어 품사 기반 온톨로지 구축 방법 및 차량 서비스 적용 방안

차시호,류민우 (사)디지털산업정보학회 2021 디지털산업정보학회논문지 Vol.17 No.4

Knowledge graph is a technology that improves search results by using semantic information based on various resources. Therefore, due to these advantages, the knowledge graph is being defined as one of the core research technologies to provide AI-based services recently. However, in the case of the knowledge graph, since the form of knowledge collected from various service domains is defined as plain text, it is very important to be able to analyze the text and understand its meaning. Recently, various lexical dictionaries have been proposed together with the knowledge graph, but since most lexical dictionaries are defined in a language other than Korean, there is a problem in that the corresponding language dictionary cannot be used when providing a Korean knowledge service. To solve this problem, this paper proposes an ontology based on the parts of speech of Korean. The proposed ontology uses 9 parts of speech in Korean to enable the interpretation of words and their semantic meaning through a semantic connection between word class and word class. We also studied various scenarios to apply the proposed ontology to vehicle services.

차량 애드혹 네트워크의 빈번한 토폴로지 변경에 적합한 기회적 브로드캐스트 프로토콜

차시호,류민우 (사)디지털산업정보학회 2022 디지털산업정보학회논문지 Vol.18 No.2

The message propagation between vehicles must be efficiently performed to quickly transmit information between vehicles in vehicle ad hoc networks (VANETs). Broadcasting can be the most effective solution for propagating these messages. However, broadcasting can cause broadcast storm problems, which can reduce the performance of the overall network. Therefore, rapid information delivery in VANET requires a method that can propagate messages quickly without causing the broadcast storm problems. This paper proposes a lightweight and opportunistic broadcast (LOB) protocol that leverages the features of opportunistic routing to propagate messages quickly while minimizing the load on the network in VANETs where the network topology changes frequently. LOB does not require any routing information like greedy forwarding scheme, and neighboring nodes at the farthest distance within the range of transmission nodes are likely to be selected as forwarding nodes, and multiple forwarding candidate nodes like opportunistic routing scheme can increase packet transmission rates. Simulation results using ns-2 showed that LOB outperformed existing broadcast protocols in terms of packet rate and packet delay.

사물 웹(WoT) 환경에서 네트워크 모니터링 애플리케이션 개발을 위한 웹 프론트엔드 프레임워크의 적용 현황 및 트렌드

차시호 (사)디지털산업정보학회 2022 디지털산업정보학회논문지 Vol.18 No.1

All things connected to the Internet have to ensure interoperability between each other. Web of Things (WoT) is an Internet of Things (IoT) Web standard technology that enables the communication between smart devices and web-based applications. In order for WoT to be possible, monitoring of all devices connected to the Internet have to be possible. To this end, various efforts are being made to develop network monitoring applications using the latest Web front-end frameworks, not traditional web-based monitoring. This paper examines and describes the possibilities of applying Web front-end frameworks such as React, Angular and Svelte to the development of network monitoring applications for WoT. This paper also describes the pros and cons of two major frameworks, React and Angular, in developing monitoring applications that support the cross-platforms and cross-browsers in WoT environments and examines the applicability of them by developing simple network monitoring applications using React.