• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.8B
• /
• pp.509-520
• /
• 2007

In this paper, we propose a real-time sensor node platform that guarantees the real-time scheduling of periodic and aperiodic tasks through a multitask-based software decomposition technique. Since existing sensor networking operation systems available in literature are not capable of supporting the real-time scheduling of periodic and aperiodic tasks, the preemption of aperiodic task with high priority can block periodic tasks, and so periodic tasks are likely to miss their deadlines. This paper presents a comprehensive evaluation of how to structure periodic or aperiodic task decomposition in real-time sensor-networking platforms as regard to guaranteeing the deadlines of all the periodic tasks and aiming to providing aperiodic tasks with average good response time. A case study based on real system experiments is conducted to illustrate the application and efficiency of the multitask-based dynamic component execution environment in the sensor node equipped with a low-power 8-bit microcontroller, an IEEE802.15.4 compliant 2.4GHz RF transceiver, and several sensors. It shows that our periodic and aperiodic task decomposition technique yields efficient performance in terms of three significant, objective goals: deadline miss ratio of periodic tasks, average response time of aperiodic tasks, and processor utilization of periodic and aperiodic tasks.

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10a
• /
• pp.477-479
• /
• 1998

인터넷상에서의 다자간 회의는 수천명의 참가하는 대규모의 회의가 될 수 있으므로 다자간 회의 시스템에서는 확장성이 중요하다. 현재의 인터넷상에서의 다자간 회의 시스템은 대부분 RTP/RTCP를 이용하는데. RTCP를 이용한 피드백 정보 전송의 빈도 수와 전송 시간의 동기화 현상이 다자간 회의 시스템의 확장성에 큰 영향을 준다. 즉, 세션 참가자 수가 증가함에 따라 네트워크에 전송되는 RTCP 패킷의 숫자가 기하급수적으로 증가하게 된다. 피드백 정보의 전송 빈도 수 감소와 동기화 현상을 방지하기 위해 도입한 무작위 지연기법은 너무 단순하여 수많은 참가자들이 동시에 피드백 정보를 교환할 때에 피드백 정보 전송시간의 동기화 현상을 피하지 못해 네트워크에 혼잡 상태를 유발할 수 있다. 이러한 혼잡을 예방하기 위한 기존의 RTP/RTCP 확장 기법의 피드백 정보 전송지연은 송신자가 수신자의네트워크 상태에 따라 효율적으로 전송을 제어할 수 없게 한다. 본 논문에서는 RTP/RTCP 확장성을 증가시키는 기존의 기법들의 성능을 평가하고, 확장성 증가와 동시에 성능이 향상된 RTP/RTCP 확장 기법을 제안한다. 본 논문에서는 확장성 증가와 피드백 지연 정도를 줄이기 위해 빠른 제고 기법을 제안한다. 빠른 재고 기법은 두가지 세부 기법으로 나누어지는데, 첫째는 네트워크의 상태의 변화에 따라 RTCP피드백 정보의 전송지연 정도를 조절하는 것이고, 둘째는 무작위 지연을 선택적으로 조정하려 피드백 정보를 오랜 기간 동안에 보내지 못한 참가자에게 우선권을 주는 것이다. 본 논문에서는 시뮬레이션을 통해 제안된 확장성 기법을 이용할 때에 기존 방식에 비해 거의 비슷한 확장성을 보이면서도 초기 RTCP패킷 전송지연이 50%정도 감소함을 보여준다.구현되고 있다.팔일 전송 기법을 각각 제시하고 실험을 통해 이들의 특성을 비교분석하였다.미에서 uronic acid 함량이 두 배 이상으로 나타났다. 흑미의 uronic acid 함량이 가장 많이 용출된 분획은 sodium hydroxide 부분으로서 hemicellulose구조가 polyuronic acid의 형태인 것으로 사료된다. 추출획분의 구성단당은 여러 곡물연구의 보고와 유사하게 glucose, arabinose, xylose 함량이 대체로 높게 나타났다. 점미가 수가용성분에서 goucose대비 용출함량이 고르게 나타나는 경향을 보였고 흑미는 알칼리가용분에서 glucose가 상당량(0.68%) 포함되고 있음을 보여주었고 arabinose(0.68%), xylose(0.05%)도 다른 종류에 비해서 다량 함유한 것으로 나타났다. 흑미는 총식이섬유 함량이 높고 pectic substances, hemicellulose, uronic acid 함량이 높아서 콜레스테롤 저하 등의 효과가 기대되며 고섬유식품으로서 조리 특성 연구가 필요한 것으로 사료된다.리하였다. 얻어진 소견(所見)은 다음과 같았다. 1. 모년령(母年齡), 임신회수(姙娠回數), 임신기간(姙娠其間), 출산시체중등(出産時體重等)의 제요인(諸要因)은 주산기사망(周産基死亡)에 대(對)하여 통계적(統計的)으로 유의(有意)한 영향을 미치고 있어 $25{\sim}29$세(歲)의 연령군에서, 2번째 임신과 2번째의 출산에서 그리고 만삭의 임신 기간에, 출산시체중(出産時體重) $3.50{\sim}3.99kg$사이의 아이에서 그 주산기사망률(周産基死亡率)이 각각 가장 낮았다. 2. 사산(死産)과 초생아사망(初生兒死亡)을 구분(區分)하여 고려해

• Journal of Korea Spatial Information System Society
• /
• v.1 no.2 s.2
• /
• pp.47-62
• /
• 1999

To meet the interoperability requirements associated with geospatial data access and geoprocessing, much efforts to design prototypical systems conforming to $OpenGIS^{TM}$ specification has been made. With respect to Object Web GIS, however, current internet mapping technology mainly focuses on either developing mapping libraries or client applications regardless of the future needs for interoperability such as an integration of $OpenGIS^{TM}$ standard for CORBA. In this paper, we propose an $OpenGIS^{TM}$ compliant mapping kernel. OpenViews, which is designed to meet those requirements. The kernel of OpenViews encapsulates the process of acquiring geospatial data in the format of $OpenGIS^{TM}$ Geometry through ORB(Object Request Broker). OpenViews, being designed based on well-known design patterns, is a highly extensible in that programmers can easily customize it on the object oriented architecture. The components implemented in OpenViews are CORBA/Java objects, and as such are portable and scalable in a networked environment. A companion package, OpenBroker, is also developed as a portable geoprocessing application server to facilitate the implementation and configuration of server side CORBA objects. It can be used for implementing objects for spatial analysis service which would be independent of legacy spatial database systems in many cases. OpenViews, together with OpenBroker, has been successfully prototyped using the technologies including EJB and servlet as the core components of an Open GIS compliant internet mapping.

• Journal of KIISE:Information Networking
• /
• v.36 no.1
• /
• pp.34-42
• /
• 2009

In this paper, we propose a practical hybrid transport error control scheme to provide SVC video streaming service over error-prone IP networks. Many error control mechanisms for various video coding standards have been proposed in the literature. However, there is little research result which can be practically applicable to the multilayered coding structure of SVC(the scalable extension of H.264/AVC). We present a new hybrid transport error control scheme that efficiently combines layered Forward Error Correction(FEC) and Automatic Repeat Request(ARQ) for better packet-loss resilience. In the proposed hybrid error control, we adopt ACK-based ARQ instead of NACK-based ARQ to maximize throughput which is the amount of effective data packets delivered over a physical link per time unit. In order to prove the effectiveness of the proposed hybrid error control scheme, we adopt NIST-Net network emulator which is a general-purpose tool for emulating performance dynamics in IP networks. It is shown by simulations over the NIST-Net that the proposed hybrid error control scheme shows improved packet-loss resilience even with much less number of overhead packets compared to various conventional error control schemes.

• The KIPS Transactions:PartC
• /
• v.8C no.5
• /
• pp.573-584
• /
• 2001

Policy-Based Network Management (PBNM) architecture is to meet various needs of network users and to provide effective management facilities in distributed and large scale networks to network managers. In PBNM, network managers perform network management operations by stipulating a set of rules rather than control each network component. On the other hand, providing security services such as authentication, privacy of messages as well as a new flexible and extensible administration framework, SNMPv3 enables network managers to monitor and control the operation of network components more secure way than ever before. Despite of its enhanced security services, SNMPv3 has difficulties in managing distributed, large-scaled network because it does not provide centralized security management facilities. In this paper, we propose a new security model called Role-based Security Management model (RSM) with security management policy to support scalable and centralized security management for SNMP-based networks. Also, the structure and the operation of the security system as well as the efficiency analysis of RSM in terms of security management are also described.

• Journal of Korea Society of Industrial Information Systems
• /
• v.23 no.1
• /
• pp.13-21
• /
• 2018

AGVS (Automated Guided Vehicle System) is a core technology of logistics automation which automatically moves specific objects or goods within a certain work space. Conventional AGVS generally requires the in-door localization system and each AGV equips expensive sensors such as laser, magnetic, inertial sensors for the route recognition and automatic navigation. thus the high installation cost is inevitable and there are many restrictions on route(path) modification or expansion. To address this issue, in this paper, we propose a cost-effective and scalable AGV based on a light-weight pattern recognition technique. The proposed pattern recognition technology not only enables autonomous driving by recognizing the route(path), but also provides a technique for figuring out the loc ation of AGV itself by recognizing the simple patterns(bar-code like) installed on the route. This significantly reduces the cost of implementing AGVS as well as benefiting from route modification and expansion. In order to verify the effectiveness of the proposed technique, we first implement a pattern recognition algorithm on a light-weight MCU(Micro Control Unit), and then verify the results by implementing an MCU_controlled AGV prototype.

• Journal of KIISE
• /
• v.41 no.9
• /
• pp.674-685
• /
• 2014

The Knowledge service system needs to infer a new knowledge from indicated knowledge to provide its effective service. Most of the Knowledge service system is expressed in terms of ontology. The volume of knowledge information in a real world is getting massive, so effective technique for massive data of ontology is drawing attention. This paper is to provide the method to infer massive data-ontology to the extent of RDFS, based on cloud computing environment, and evaluate its capability. RDFS inference suggested in this paper is focused on both the method applying MapReduce based on RDFS meta table, and the method of single use of cloud computing memory without using MapReduce under distributed file computing environment. Therefore, this paper explains basically the inference system structure of each technique, the meta table set-up according to RDFS inference rule, and the algorithm of inference strategy. In order to evaluate suggested method in this paper, we perform experiment with LUBM set which is formal data to evaluate ontology inference and search speed. In case LUBM6000, the RDFS inference technique based on meta table had required 13.75 minutes(inferring 1,042 triples per second) to conduct total inference, whereas the method applying the cloud computing memory had needed 7.24 minutes(inferring 1,979 triples per second) showing its speed twice faster.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.6
• /
• pp.567-581
• /
• 2008

As the size of the web is growing explosively, search engines are becoming increasingly important as the primary means to retrieve information from the Internet. A search engine periodically downloads web pages and stores them in the database to provide readers with up-to-date search results. The web crawler is a program that downloads and stores web pages for this purpose. A large-scale search engines uses a parallel web crawler to retrieve the collection of web pages maximizing the download rate. However, the service architecture or experimental analysis of parallel web crawlers has not been fully discussed in the literature. In this paper, we propose an architecture of the parallel web crawler and discuss implementation issues in detail. The proposed parallel web crawler is based on the coordinator/agent model using multiple machines to download web pages in parallel. The coordinator/agent model consists of multiple agent machines to collect web pages and a single coordinator machine to manage them. The parallel web crawler consists of three components: a crawling module for collecting web pages, a converting module for transforming the web pages into a database-friendly format, a ranking module for rating web pages based on their relative importance. We explain each component of the parallel web crawler and implementation methods in detail. Finally, we conduct extensive experiments to analyze the effectiveness of the parallel web crawler. The experimental results clarify the merit of our architecture in that the proposed parallel web crawler is scalable to the number of web pages to crawl and the number of machines used.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.10a
• /
• pp.643-645
• /
• 2010

The Internet-based multimedia services such as IPTV is being expanded with the development of technology to support the convergence of broadcasting and telecommunications technology for the control seems to be growing larger. Especially for the real-time TV broadcast multicast control technology to support the authentication and resource control, in addition to the technology services that enhance the value of technology for a variety of services in both directions seems to be developed. And, Internet-based transmission system transmit the video content for the video content delivery using RTP(Real Time Transport Protocol). Standardization body, IETF(Internet Engineering Task Force) within the RTP, according to a variety of audio and video formats only transmission format(RTP Payload Format) Establish a separate standard and scalable video content "RTP Payload Format for SVC(Switched Virtual Connection) Video" the standardization is currently processing. In this paper we are improving the quality of broadcasting and telecommunication systems, so that the upper layer by the application can react adaptively to the existing MPEG2-TS and RTP who are provided by a variety of content applied to a variety of devices consumers ETE(End- to-End) QoS(Quality of Service) for enhance the system who was designed and implemented.

• Journal of KIISE:Information Networking
• /
• v.32 no.3
• /
• pp.370-381
• /
• 2005

Mobile IP provides an efficient and scalable mechanism for host mobility within the Internet. Using Mobile If, mobile nodes may change their point of attachment to the Internet without changing their If address. However, it would result in a high signaling cost. To reduce the signaling cost, we factor in the fact that mobile users will not be actively communicating much of the time. In fact, there Is no necessity to send a binding update message to the home agent when an mobile node does not communicates with others while moving. From this point of view, we propose a lazy update strategy for minimizing signaling cost using the forwarding pointer in hierarchical Mobile IPv6. In our proposal, binding updates are sent only when a mobile node is in a busy mode. If an mobile node is in a dormant mode, binding update messages are delayed until busy mode using the forwarding pointer. As a result, our proposal can reduce the total signaling cost by eliminating unnecessary binding update messages when a mobile node Is in a dormant mode. In addition to, our proposal reduces unnecessary location update cost resulting from ping-pong effect under mobile node's dormant mode. Analysis results using the discrete analytic model presented in this paper shows that our proposal can has superior performance than hierarchical Mobile nv6 when the call-to-mobility ratio is low and the length of the forwarding pointer chain K is low.