• Journal of KIISE:Databases
• /
• v.33 no.3
• /
• pp.283-298
• /
• 2006

The TPR-tree is the time-parameterized indexing scheme that supports the querying of the current and projected future positions of such moving objects by representing the locations of the objects with their coordinates and velocity vectors. If this index is, however, used in environments that directions and velocities of moving objects, such as vehicles, are very often changed, it increases the communication cost between the server and moving objects because moving objects report their position to the server frequently when the direction and the velocity exceed a threshold value. To preserve the communication cost regularly, there can be used a manner that moving objects report their position to the server periodically. However, the periodical position report also has a problem that lineal time functions of the TPR-tree do not guarantee the accuracy of the object's positions if moving objects change their direction and velocity between position reports. To solve this problem, we propose the query processing scheme and the data structure using road networks for predicting uncertainty positions of moving objects, which is reported to the server periodically. To reduce an uncertainty of the query region, the proposed scheme restricts moving directions of the object to directions of road network's segments. To remove an uncertainty of changing the velocity of objects, it puts a maximum speed of road network segments. Experimental results show that the proposed scheme improves the accuracy for predicting positions of moving objects than other schemes based on the TPR-tree.

• Journal of KIISE:Computer Systems and Theory
• /
• v.34 no.11
• /
• pp.572-580
• /
• 2007

Wireless sensor networks are sensing, computing and communication infrastructures that allow us to monitor, instrument, observe, and respond to phenomena in the harsh environment. Generally, the wireless sensor networks are composed of many deployed sensor nodes that were designed to be very cost-efficient in terms of production cost. For example, UC Berkeley's MICA motes have only 8-bit CPU, 4KB RAM, and 128KB FLASH memory space. Therefore, sensor operating systems that run on the sensor nodes should be able to operate efficiently in terms of the resource management. In this paper, we present a dynamic threads stack management scheme for space-constrained and multi-threaded sensor operating systems. In this scheme, the necessary stack space of each function is measured on compile-time. Then, the information is used to dynamically allocate and release each function's stack space on run-time. It was implemented in Nano-Qplus sensor operating system. Our experimental results show that the proposed scheme outperforms the existing fixed-size stack allocation mechanism.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10c
• /
• pp.391-393
• /
• 2001

이동컴퓨팅 환경에서 호스트의 이동성으로 야기되는 멀티미디어 데이터전송 문제 해결에 관한 연구가 활발히 진행되고 있다 . 멀티캐스트는 멀티미디어 데이터가 차지하는 많은 네트워크 트래픽을 수신자에게 효율적으로 분배함으로써 네트워크 트래픽을 줄일수 있다. 그러나 이동 호스트를 대상으로 하는 멀티캐스트는 무선자원의 효율적 사용을 위해 셀 반경이 작아짐에 따라 빈번하게 그룹의 멤버와 위치를 변화시키기 때문에 라우팅 경로의 최적화, 투명성 제공, 잦은 핸드오프로 인한 등록지연에 따른 서비스 단절과 패킷손실의 증가에 대한 명확한 대책이 제시되지 못하고 있다. 또한 멀티캐스트를 지원하지 않는 영역으로 이동했을 때의 데이터전송에 관한 문제점도 내포하고 있다. 본 논문에서는 이러한 문제의 해결방안으로 이동컴퓨팅환경에서 Hop Counter로 정의된 서비스 범위를 하나의 그룹이라 정의하고 그룹기반의 멀티캐스트 라우팅 방법을 제안한다. 제안 방법은 셀이 마이크로화됨에 따라 나타나는 Hop 증가에 따른 전송 오버로드와 터널링 문제를 해결하고, 광역 네트워크에서의 멀티캐스팅을 담당하는 에이전트의 부하를 감소시킴으로써 성능 향상을 기대할 수 있다. 또한 호스트가 이동한 FA가 멀티캐스트를 지원하지 않을 때 MA가 그룹의 특정 호스트로부터 보낸 데이터를 받기 위해서 주변에 인접해 있는 MA중 멀티캐스트를 지원하고 가장 작은 Hop을 갖은 MA를 터널의 대리자로 등록해 놓음으로써 멀티캐스팅이 지원되지 않은 환경에서의 멀티캐스팅이 이루어질 수 있다.

• Journal of the Economic Geographical Society of Korea
• /
• v.27 no.3
• /
• pp.174-191
• /
• 2024

This study analyzed the spatiotemporal evolution of Korean multinational corporations' (MNCs') foreign direct investment (FDI) networks from 1978 to 2023, focusing on Samsung Electronics and LG Electronics. Using data on the consolidated overseas subsidiaries of these two companies, a two-mode network was constructed to examine the status of host countries through the betweenness centrality index and to identify types of countries with similar value chain arrangements by investigating their linkage structures. The main findings are as follows. First, during the early phase of Korean electronics MNCs' overseas expansion in the 1980s, they primarily established sales bases in developed consumer markets. However, over time, they gradually expanded into other business areas, including manufacturing, producer services, and R&D, increasing complexity in their FDI networks as cross-border mergers and acquisitions (M&As) became more frequent. Second, the United States has remained central to these MNCs' FDI networks since the 1980s, but more recently, China has emerged as a significant hub, challenging the U.S. in global value chains. Third, emerging Asian economies, including India, Vietnam, and Indonesia, have strengthened their positions due to the diversification of MNCs' investment objectives from manufacturing bases to a broader range of business areas. Finally, since the 2010s, the convergence of the electronics industry with the automotive electronics sector and new industries has led to a diversification of the value chain arrangements of Korean electronics MNCs.

• The Journal of Korean Association of Computer Education
• /
• v.20 no.6
• /
• pp.95-104
• /
• 2017

The damage caused by information spill, forgery, falsification, and deletion by cyber infringement in educational institutions and universities is very large. In this study, we analyzed the types, causes, and problems of cyber infringement in educational administrative institutions and universities. As a result, administrative, physical and technical information protection activities were weak. In this paper, we propose a security enhancement method for each domain by dividing them into Internet zone, network-neutral zone (DMZ: Demilitarized Zone), general server zone, internal server zone (Server Farm), and user zone so that these vulnerabilities can be easily identified, supplemented or security enhanced. In addition, we have proposed a method to apply security information system architecture and information protection technology correctly for educational administration institutions and universities. This study is meaningful not to provide conceptual guidance but to suggest specific action and procedure oriented security management plan.

• Convergence Security Journal
• /
• v.13 no.2
• /
• pp.85-93
• /
• 2013

Today, the structure of terrorist organizations in the form of a variety of network complexity are evolving. However, terrorist organization not combining randomly generated network but preferential attachment a network. So, it's research should be preceded a better understanding about the characteristics and type of terror network for a effective counter-terrorism policy of law enforcement. In addition, the appropriate response strategy have to technique establish in an era of smart media. In particular, homegrown terrorist attacks on unspecified people without boundaries of countries and regions unlike the traditional terrorism. Also, homegrown terrorism are violence and criminal activity by new various of religion, politics, philosophy. Besides the extreme members of homegrown terror networks went grow up through the evolutionary process in the age of smart media. Law enforcement agencies must identify the terrorist network at the national level. Therefore, terror networks evolving in the online space, forming a radical homegrown terror organizations have access to the network. Intelligence community track terrorist networks and to block the negative aspects of the smart media outlets should be considered.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1998.10a
• /
• pp.193-196
• /
• 1998

효율적인 글로벌 생산경영은 각국에 위치한 생산시설을 통제·운영(control)해야 하는 글로벌 기업(다국적기업)에게 중요한 문제가 되고 있다. 각 나라에 위치한 생산시설은 글로벌기업의 생산네트워크를 구성하는데, 효율적인 글로벌 생산경영을 위해서는 이러한 글로벌 생산네트워크가 최적으로 운영되어야 한다. 글로벌기업은 협력·조정 메커니즘(coordination mechanism)을 통하여 이를 달성할 수 있다. 글로벌 협력·조정 메커니즘(global coordination mechanism)이란 글로벌 기업의 본사와 해외자회사 모두의 생산활동에 상호 영향을 미치는 의사결정을 하는데 있어서 서로 협력하고 조정할 수 있도록 해주는 조직적 의사결정지원 시스템의 하나이다. 이는 협력·조정의 영역, 방법, 구조 등 세가지 기본 틀을 살펴봄으로써 이해될 수 있다는 것이 본 논문의 기본 전제이다. 이 논문에서는 한국 글로벌기업의 본사와 해외 자회사간 협력·조정 활동을 분석하여, 해외 자회사의 생산성과를 높이기 위한 효과적인 협력·조정 메커니즘의 결정요소를 파악하고자 한다. 실증분석을 통하여 다음과 같은 가설을 검증한다. (1) 산업의 특성은 협력·조정 메커니즘과 글로벌 생산성과 간의 상호관계에 영향을 미친다. (2) 글로벌기업의 특성(예를 들어, 기업의 글로벌화 정도, 규모)은 협력·조정 메커니즘과 글로벌 생산성과 간의 상호관계에 영향을 미친다. (3) 산업과 기업의 특성을 반영하여 협력·조정 메커니즘의 구성요소 (협력·조정 영역, 방법, 및 구조) 간의 적합성(fit)이 이루어졌을 때 글로벌 생산성과는 가장 높다.

• Journal of Korea Multimedia Society
• /
• v.10 no.8
• /
• pp.1068-1077
• /
• 2007

This paper proposes a method that extracts characteristics of cracks such as length, thickness and direction from a concrete slab surface image with image processing techniques. These techniques extract the cracks from the concrete surface image in variable conditions including bad image conditions) using the ART2-based RBF network to recognize the dominant directions -45 degree, 45 degree, horizontal and vertical) of the extracted cracks from the automatically calculated specifications like the lengths, directions and widths of the cracks. Our proposed extraction algorithms and analysis of the concrete cracks used a Robert operation to emphasize the cracks, and a Multiple operation to increase the difference in brightness between the cracks and background. After these treatments, the cracks can be extracted from the image by using an iterated binarization technique. Noise reduction techniques are used three separate times on this binarized image, and the specifications of the cracks are extracted form this noiseless image. The dominant directions can be recognized by using the ART2-based RBF network. In this method, the ART2 is used between the input layer and the middle layer to learn, and the Delta learning method is used between the middle layer and the output layer. The experiments using real concrete images showed that the cracks were effectively extracted, and the Proposed ART2-based RBF network effectively recognized the directions of the extracted cracks.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.6 s.348
• /
• pp.39-45
• /
• 2006

n a hybrid ad-hoc network, wired network and a mobile ad-hoc network are connected by the internet gateway. To provide seamless service for internet users in the hybrid ad-hoc network, an efficient internet gateway selection technique and a fast handover technique are needed. In this paper, we propose a seamless handoff technique for providing mobility of mobile hosts in hybrid ad-hoc networks. The proposed internet gateway re-registration algorithm improves general handoff performance. Moreover, the handoff processing time within certain range of area is reduced by using mobility management agent(MMA). In addition the packet loss is reduced when handoff occurs out of the range of MMA by tunneling technique.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04b
• /
• pp.67-69
• /
• 2002

여러 사이트에서 구축된 공간 데이터를 효율적으로 관리 및 공유하기 위해서는 대용량의 정보를 처리할 수 있는 분산 공간 데이터베이스 시스템의 사용이 필수적이다. 이러한 분산 공간 데이터베이스 시스템상에서의 분산 공간 죠인 질의는 공간 데이터의 대용량성과 그 복잡성으로 인하여 공간 연산의 지펴져 부하와 네트워크상의 전송 부하를 발생시킨다. 이러한 문제를 해결하기 위해 세미죠인 기반의 공간 죠인 기법들이 제안되었으나 공간 죠인 연산을 특정 서버에서만 수행하여 병목현상을 발생시키기 때문에 결국 질의 처리시간이 증가된다. 본 논문은 이러한 분산 공간 데이터베이스 시스템에서 수행 비용이 많이 드는 원격 사이트간의 공간 죠인 연산에 대해 R+-tree 공간 색인을 사용하여 병렬적으로 수행하는 기법을 제안한다. 본 기법은 R+-tree 공간 색인을 이용하여 공간 죠인 연산의 대상이 되는 릴레이션들을 중첩이 없는 두개의 릴레이션들로 분할한 후 질의 수행에 참여하는 두 서버에 죠인 연산을 분배하고 병렬적으로 처리하여 결과들을 병합한 다음 클라이언트에게 전송만다. 본 기법은 릴레이션을 분할하여 각 서버에서 공간 죠인 연산을 병렬적으로 처리하므로 처리 비용을 절반으로 감소시키며. R+-tree의 영역에 해당하는 객체들만 죠인 연산에 참여하게 함으로써 네트워크 전송 비용을 감소시킨다