• The Journal of the Korea Contents Association
• /
• v.16 no.4
• /
• pp.224-230
• /
• 2016

Recently, CCN(Content Centric Network) has been extensively interested in the literature to transfer data traffic efficiently according to the rapid growth of multimedia services on the Internet. CCN is a new networking paradigm to deliver contents efficiently based on the named content not the named or addressed host. This paper presents a mathematical approach for analyzing CCN-caching systems with two routers. Considering the stochastic characteristics of communication networks, the caching system is modeled as a two dimensional Markov chain. This paper analyzes the structural feature of the transition rate matrix in the Markov chain and presents a numerical solution for the CCN-caching performance of the two router system. In addition, various numerical examples are presented.

• Korean Journal of Computational Design and Engineering
• /
• v.2 no.2
• /
• pp.93-102
• /
• 1997

Most design changes are due to interferences and fit-up as parts are assembled if such a large product as an automobile or an aircraft is developed by many concurrent engineers. In this part (1) of the thesis, the assembly-centric modeling methodology with CAD systems is proposed in order to reduce the design changes. Unlike part-centric modeling method, a part is modeled with its own coordinate system which is used in downstream process as machining and measuring. The part coordinates initially have the same orientation as its assembly which is predefined in BOM (Bill of Material). Then, the corrdinates origin of the part is moved to its location to be assembled from that of its assembly coordinate system. To implement this methodology, the position data of the part w.r.t. its assembly are stored in a database to build the same hierarchical assembling structure as BOM structure. This modeling approach has the advantage of reflecting asembling sequence, because the process of positioning parts is similar to that of real assembling. And with the method, a designer can easily adjust all of the part positions of an assembly to resolve interferences if he modifies just the coordinates origin of the assembly, which results in moving included parts and assemblies together.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.9
• /
• pp.4572-4586
• /
• 2019

Mobile Edge Computing (MEC) and Information-Centric Networking (ICN) are essential network architectures for the future Internet. The advantages of MEC and ICN such as computation and storage capabilities at the edge of the network, in-network caching and named-data communication paradigm can greatly improve the quality of video streaming applications. However, the packet loss in wireless network environments still affects the video streaming performance and the existing loss recovery approaches in ICN does not exploit the capabilities of MEC. This paper proposes a Deep Learning based Loss Recovery Mechanism (DL-LRM) for video streaming over MEC based ICN. Different with existing approaches, the Forward Error Correction (FEC) packets are generated at the edge of the network, which dramatically reduces the workload of core network and backhaul. By monitoring network states, our proposed DL-LRM controls the FEC request rate by deep reinforcement learning algorithm. Considering the characteristics of video streaming and MEC, in this paper we develop content caching detection and fast retransmission algorithm to effectively utilize resources of MEC. Experimental results demonstrate that the DL-LRM is able to adaptively adjust and control the FEC request rate and achieve better video quality than the existing approaches.

• Journal of the Korea Society for Simulation
• /
• v.22 no.1
• /
• pp.9-20
• /
• 2013

Defense M&S for weapons effectiveness is a realistic way to support virtual warfare similar to real warfare. As the war paradigm becomes platform-centric to network-centric, people try to utilize smartphones as the source of sensor, and command/control data in the simulation-based weapons effectiveness analysis. However, there have been limited researches on integrating smartphones into the weapon simulators, partly due to high modeling cost - modeling cost to accomodate client-server architecture, and re-engineering cost to adapt the simulator on various devices and platforms -, lack of efficient mechanisms to exchange large amount of simulation data, and low-level of security. In this paper, we design and implement Smartphone Adaptor to utilize smartphones for the simulationbased weapons effectiveness analysis. Smartphone Adaptor automatically sends sensor information, GPS and motion data of a client's smartphone to a simulator and receives simulation results from the simulator on the server. Also, we make it possible for data to be transferred safely and quickly through JSON and SEED. Smartphone Adaptor is applied to OpenSIM (Open simulation engine for Interoperable Models) which is an integrated simulation environment for weapons effectiveness analysis, under development of our research team. In this paper, we will show Smartphone Adaptor can be used effectively in constructing a Live simulation, with an example of a chemical simulator.

• Journal of KIISE:Databases
• /
• v.37 no.6
• /
• pp.315-323
• /
• 2010

In Wireless Sensor Networks (WSNs), various Data-Centric Storages (DCS) schemes have been proposed to store the collected data and to efficiently process a query. A DCS scheme assigns distributed data regions to sensor nodes and stores the collected data to the sensor which is responsible for the data region to process the query efficiently. However, since the whole data stored in a node will be lost when a fault of the node occurs, the accuracy of the query processing becomes low, In this paper, we propose an in-network aggregation query processing method that assures the high accuracy of query result in the case of data loss due to the faults of the nodes in the DCS scheme. When a data loss occurs, the proposed method creates a compensation model for an area of data loss using the linear regression technique and returns the result of the query including the virtual data. It guarantees the query result with high accuracy in spite of the faults of the nodes, To show the superiority of our proposed method, we compare E-KDDCS (KDDCS with the proposed method) with existing DCS schemes without the data-loss correction method. In the result, our proposed method increases accuracy and reduces query processing costs over the existing schemes.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.17 no.1
• /
• pp.89-106
• /
• 1987

The author obtained individualized lateral cephalometric tomograms from 23 young adults (46 of left and right normal TMJ) with normal occlusion and 20 patients (14 of patient asymptomatic TMJ and 26 of patient symptomatic TMJ) with clicking and painful TMJ after the analysis of submental vertex view. Individualized lateral cephlometric tomogram analysis and TMJ space analysis were performed after tracing each film. All data from these analysis was recorded and statistically processed with CYBER computer system. 1. The results were obtained as follows. In submental vertex view, the mean condylar angulation of Rt. side in normal group was 20.348°±6.358°, Lt. side was 18.870°±7.777° and Rt. side in patient group was 19.350°±7.576° Lt. side was 17.750°±6.146° respectively. The mean condylar angulation of Rt. side was larger than Lt. side in normal and patient group. 2. When the mandible was moved from centric occlusion to centric relation, condylar position relating to the glenoid fossa was placed posteriorly and superiorly in normal TMJ group and patient symptomatic TMJ group. 3. In centric relation position, the proportion of anterior space to posterior space was 1.593 for normal TMJ group, 1.604 for patient asymptomatic TMJ group and 1.671 for patient symptomatic TMJ group. In centric occlusion position, 1.390 for normal TMJ group, 1.539 for patient asymptomatic TMJ group and 1.196 for patient symptomatic group. Normal TMJ group, patient asymptomatic TMJ group and patient symptomatic TMJ group and patient symptomatic TMJ group revealed significant difference in ∠C₂ measurement. (ANOVA-test, p<0.05) 5. Normal group and patient group revealed significant difference in Fh, ∠C₁and ∠C₂ measurement. (T-test, p<0.05) 6. There were strong positive correlation (0.8771) between Fp and Fm, and strong negative correlation (-0.9039) between ∠C₂ and ∠C₁ from the lateral cephalometric tomogram analysis.

• Journal of Information Technology Applications and Management
• /
• v.15 no.3
• /
• pp.195-208
• /
• 2008

In an emergency management case, evaluating the economic value of information technology investments is a challenging problem due to the effects of decision making, uncertainty of disasters, and difficulty of measurements. Risk assessment and recovery process, one of the major functions in emergency management, consists of (1) measurement of damages or losses, (2) recovery planning, (3) reporting and approving budgets, (4) auctioning off recovery projects to constructors, and (5) construction for the recovery. Specifically and of our interest, measurement of damages or losses is often a costly and time-consuming process because the wide range of field surveys should be performed by a limited pool of trained agents. Managers, therefore, have to balance accuracy of the field survey against the total time to complete the survey. Using information technologies to support field survey and reporting has great potential to reduce errors and lowers the cost of the process. However, existing cost benefit analysis framework may be problematic to evaluate and justify the IT investment because the cost benefit analysis often include the long-run benefit of IT that is difficult to quantify and overlook the impact of managerial control upon the investment outcomes. Therefore, we present an alternative cost-centric control model that conservatively quantifies all cost savings to replace benefits in cost benefit analysis and incorporate the managerial control. The model provides a framework to examine how managerial decision making and uncertainty of disaster affect the economic value of IT investments. The current project in Emergency Agency in South Korea is introduced as a case to apply the cost-centric control model. Our work helps managers to better evaluate and justify IT-related investment alternatives in emergency management.

• Journal of Digital Contents Society
• /
• v.14 no.3
• /
• pp.357-365
• /
• 2013

The popularization of smart phones changes the usage patterns of mobile communication from voice-centric to data-centric communication. The demand for wireless data communications is rapidly increasing, and thus the need for expanding infrastructure for mobile communication is also rapidly increasing. In this paper, we propose a scheme for reducing the cost for the mobile communication infrastructure by exploiting opportunistic networks in dissemination of multimedia contents. By using this scheme, the large portion of the cost for mobile communication infrastructure could be saved, and the need of users for multimedia contents could be also fulfilled. Our scheme is evaluated using agent-based simulations. The simulation results show that about 70% of mobile communication can be replaced with the data communication through opportunistic networks.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2021.07a
• /
• pp.113-116
• /
• 2021

우리나라는 최근 COVID-19 감염병 재난에 대한 체계적이고 성공적인 방역과 대응으로 국제적인 주목과 인정을 받고 있으며, 세계 10위 수준의 국가 경제 발전과 재난관리 중요성의 인식 향상에 따라 수준 높은 국가 재난관리 체계에 대한 국민적 관심과 요구가 높아지고 있다. 2004년 국가 위기관리 기본지침의 제정과 함께 국가 위기관리 표준 매뉴얼이 수립된 이래로 국가 위기관리 체계에서 위기관리 매뉴얼은 중추적인 역할을 담당하고 있다. 하지만 4차시대 혁명시대 ICT 기술 및 재난정보들이 융합된 재난 대응 환경에서 책자와 파일 위주의 정적 문서 포맷과 비구조적인 내용구성으로 주요정보 간 연계·활용성이 낮은 현재 매뉴얼 체계는 실제 재난상황에서 KEY 역할을 수행하기에는 여러 측면에서 한계가 뚜렷하다. 본 논문에서는 국가 위기관리 매뉴얼 체계 개선의 초석을 마련하는 단계로써 표준 매뉴얼에 대한 구성요소를 분석하고 기관 간 협업관계를 분석하였다.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2022.07a
• /
• pp.169-172
• /
• 2022

재난안전 분야의 기술개발 동향을 파악하고 지적 관계를 분석하기 위한 연구에서 신뢰성과 최신성을 겸비한 학술정보를 활용하는 것은 매우 유용하다. 기존의 논문 기반 계량정보분석 연구에서는 관련 분야의 학술지와 키워드를 중심으로 분석 대상 논문을 선별하여 연구재료로 사용하였다. 본 논문에서는 재난안전 분야의 보다 세부적인 연구 특성 파악을 위해 국내 대학기관의 방재 및 안전공학 학과에 소속된 저자들의 논문 정보를 대상으로 기관식별, 학과유형 분류, 재난안전유형 분류. 표준산업분류를 매핑하고 주요 측면별로 분석 연구를 수행하였다. 분석 결과, 재난안전 분야 연구에서 저자소속 기관의 유형 및 지역적 분포, 공저 학과 유형의 구성, 재난안전유형 및 표준산업분류의 현황과 핵심 키워드가 자세히 파악되었다. 연구 결과는 향후 지능형 위기경보 체계 구축을 위한 재난유형별 주요 기관 및 전문가 식별과 추천에 활용이 기대된다.