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.

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.

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.

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.

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.

차량 밀도가 낮은 VANET 환경을 위한 지연 허용 차량 라우팅 프로토콜

차시호,류민우,조국현 大韓電子工學會 2012 電子工學會論文誌-CI (Computer and Information) Vol.49 No.4

A VANET (Vehicular Ad Hoc Network), a subclass of MANET (Mobile Ad Hoc Network), is an ad hoc network using wireless communication between vehicles without fixed infrastructure such as base station. VANET suffers a frequent link breakage and network topology change because of the rapid movement of vehicles and the density change of vehicles. From these characteristics of VANET, geographical routing protocols such as GPSR (Greedy Perimeter Stateless Routing) using only the information of neighbor nodes are more suitable rather than AODV and DSR that are used in existing MANETs. However, GPSR may have a transmission delay and packet loss by frequent link disconnection and continual local maxima under the low vehicle density conditions. Therefore, in this paper, we propose a DTVR (Delay Tolerant Vehicular Routing) algorithm that perform a DTN-based routing scheme if there is no 2-hop neighbor nodes for efficient routing under the low vehicle densities in VANETs. Simulation results using ns-2 reveal that the proposed DTVR protocol performs much better performance than the existing routing protocols. VANET(Vehicular Ad Hoc Network)은 MANET(Mobile Ad Hoc Network)의 일종으로 기지국과 같은 기반시설의 도움 없이 차량 간의 무선 통신을 통해 구성되는 임시적인 네트워크이다. VANET은 차량들의 고속 이동성이나 차량 간 밀도 변화로 인해 빈번한 링크 단절 및 네트워크 토폴로지 변화 등을 야기한다. 이러한 VANET의 특성으로 인해 기존의 MANET에서 사용되는 AODV와 DSR과 같은 경로기반 라우팅 프로토콜보다는 주변 노드의 정보만을 이용하는 GPSR(Greedy Perimeter Stateless Routing)과 같은 지리기반 라우팅 프로토콜이 매우 적합하다. 그러나 GPSR은 차량 노드의 밀도가 낮은 환경에서는 잦은 링크 단절과 반복적인 로컬 맥시멈으로 인해 전송지연 및 데이터 손실이 발생할 수 있다. 따라서 본 논문에서는 차량의 밀도가 낮은 VANET 환경에서 효율적인 라우팅을 수행하기 위해 2-hop 이웃 노드의 존재가 없는 경우에 DTN 기반의 라우팅을 수행하는 DTVR(Delay Tolerant Vehicular Routing) 알고리즘을 제안한다. ns-2를 이용한 성능분석 결과 제안된 DTVR 프로토콜이 차량 밀도가 낮은 환경에서 기존 라우팅 프로토콜보다 성능이 우수함을 입증하였다.

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.

무선 센서 네트워크를 위한 에너지 효율적인 계층적 클러스터링 알고리즘

차시호,최석만,이종언 (사)디지털산업정보학회 2008 디지털산업정보학회논문지 Vol.4 No.2

Clustering allows hierarchical structures tobe built on the nodes and enables more efficient use of scarce resources, such as frequency spectrum, bandwidth, and energu in wireless sensor networks (WSNs). This paper proposes a hierarchical clustering algorithm calle EEHC which is more energy efficient than exisiting algorithms for WSNs, It intoduces region node selection as well as cluster head eletion based on the residual battery capacity of nodes to reduce the costs of managing sensor nodes and of the communication among them. The role of cluster heads or region nodes is rotated among node. To do this, EEHC clusters peripdically to select sluster heads that are richer in residual energy level, compared to the other nodes, according to clustering policies from administrators. To prove the performance improvement of EEHC, the ns-2 simulator was used. The results show that it can reduce the energy and bandwidth consumption for organizing and managing WSNs comparing it with exisitng algorithms.

XML 기반의 포괄적인 망 관리 시스템의 설계 및 구현 : Design and Implementation of An XML-based Universal Network Management System

차시호,김규호 韓國컴퓨터情報學會 2002 韓國컴퓨터情報學會論文誌 Vol.7 No.1

현재의 망 관리자들은 관리 데이터를 검색하고 조작하기 위한 매우 고가의 특정 업체의 관리 콘솔을 사용하고 있다. 그러나, 점점 더 많은 시스템들이 웹 환경으로 변경되고 있기 때문에, 망 관리자들은 언제 어디에서나 시스템을 관리하기를 원하게 되었으며, 관리 정보에 대한 통합적이며, 비용이 효율적이고, 사용하기 쉬운 접근을 원하게 되었다. 본 논문은 이러한 요구사항들을 만족시키기 위하여 관리 콘솔을 위한 여러 인터넷 장비들을 지원하는 XML(extensible Markup Language)기반의 포괄적인 망 관리시스템(XMAN)의 구현에 대하여 설명한다. XMAN은 3-계층 구조를 가지며, 웹, XML 및 서버 측 자바 기술들의 확장에 기반하여 구현된다. Currently, network managers are making use of expensive, vendor-specific management consoles to view and manipulate network data. And more and more systems are transferred to web environment. Therefore, network managers want to get information at anywhere, anytime. This requires an access of management information to be unified, cost-effective. and easy-to-use. This paper presents the implementation of an XML-based universal network management system (XMAN), which supports multiple internet devices as management console. XMAN has 3-tire architecture, and the implementation is based on an extensive use of emerging Web, XML, and Java technologies.