• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.67-73
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• 2010

In SIP(Session Initiation Protocol) environment, the presence event notification operation makes presence service user to recognize presence information status changes of the other party. In conventional method, the user should send each SIP SUBSCRIBE message containing the address of the other party to the presence server. Furthermore each presence subscription requires refresh messages, and the amount of notification messages from the other party becomes large. These facts increases network traffic and the load of presence server. In this paper, to solve these problems a new presence list service has been suggested. It uses a presence list consists of URI of the other party and make it possible to subscribe by using one SUBSCRIBE message. So this method decreases the amount of SUBSCRIBE messages and refresh messages, and it also decreases the amount processing event notification messages from the subscribed the other party. And to increase the efficiency, a presence filtering method which enables to include some parts of selected presence information into the notification message body has been also suggested. The implemented system can reduce SIP message related network traffic and message processing time of the presence server. The performance of this proposed system has been evaluated by experiments, and the results showed decreasing of server processing time.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.2
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• pp.83-92
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• 2016

In this paper, we introduce the results of the testing and observation systems for performance wideband expansion in the Korean VLBI Network(KVN). The KVN performs VLBI observations to 1024 Mbps data rate, and 8192 Mbps observing for four simultaneous observation is now evaluating for normal operation. The VLBI stations in several world countries developed their own wideband observing systems to observe the celestial objects with high precision and high resolution or are working with several countries. The KVN is planning to introduce a high-speed sampler, OCTAD, for sampling directly up to 2048 MHz bandwidth for RF signal of K/Q/W/D band in the frequency band without conversion. Therefore, as a preliminary study for the performance scalability of the KVN then through the close cooperation with National Astronomical Observatory of Japan (NAOJ), the OCTAD high-speed sampler and OCTADISK2 high-speed recorder were installed in the KVN Yonsei station, and verify the performance through a wideband.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.471-480
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• 2006

Recently, multimedia communication services, such as video conferencing and voice over IP, have been rapidly spread. H.323 is an international standard that specifies the components, protocols and procedures that provide multimedia communication services of real-time audio, video, and data communications over packet networks, including IP based networks. H.323 is applied to many commercial services because it supports various network environments and has a good performance. But communication services based on H.323 may have some problem because of current network trouble or mis-implementation of H.323. The understanding of this problem is a critical issue because it improves the quality of service and is easy to service maintenance. In this paper, we implement the analysis system for H.323 protocol wihch includes H.245, H.225.0, RTP, RTCP, and so on. Tills system is able to capture, parse, and present the H.323 protocol in real-time. Through the operation test and performance evaluation, we prove that our system is a useful to analyze and understand the problems for communication services based on H.323.

• Journal of KIISE:Software and Applications
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• v.29 no.1_2
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• pp.114-125
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• 2002

In this paper, we are proposing a hierarchical segmentation method that first segments the video data into units of shots by detecting cut and dissolve, and then decides types of camera operations or object movements in each shot. In our previous work[1], each picture group is divided into one of the three detailed categories, Shot(in case of scene change), Move(in case of camera operation or object movement) and Static(in case of almost no change between images), by analysing DC(Direct Current) component of I(Intra) frame. In this process, we have designed two-stage hierarchical neural network with inputs of various multiple features combined. Then, the system detects the accurate shot position, types of camera operations or object movements by searching P(Predicted), B(Bi-directional) frames of the current picture group selectively and hierarchically. Also, the statistical distributions of macro block types in P or B frames are used for the accurate detection of cut position, and another neural network with inputs of macro block types and motion vectors method can reduce the processing time by using only DC coefficients of I frames without decoding and by searching P, B frames selectively and hierarchically. The proposed method classified the picture groups in the accuracy of 93.9-100.0% and the cuts in the accuracy of 96.1-100.0% with three different together is used to detect dissolve, types of camera operations and object movements. The proposed types of video data. Also, it classified the types of camera movements or object movements in the accuracy of 90.13% and 89.28% with two different types of video data.

• Journal of Korea Water Resources Association
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• v.30 no.5
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• pp.441-447
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• 1997

Rainfall observation using rain gage network or satellites includes the sampling error depending on the observation methods or plans. For example, the sampling using rain gages is continuous in time but discontinuous in space, which is nothing but the source of the sampling error. The sampling using satellites is the reverse case that continuous in space and discontinuous in time. The sampling error may be quantified by use of the temporal-spatial characteristics of rainfall and the sampling design. One of recent works on this problem was done by North and Nakamoto (1989), who derived a formulation for estimating the sampling error based on the temporal-spatial rainfall spectrum and the design scheme. The formula enables us to design an optimal rain gage network or a satellite operation plan providing the statistical characteristics of rainfall. In this paper the formula is reviewed and applied for the sampling error problems using several multi-dimensional precipitation models. The results show the limitation of the formulation, which cannot distinguish the model difference in case the model parameters can reproduce similar second order statistics of rainfall. The limitation can be improved by developing a new way to consider the higher order statistics, and eventually the probability density function (PDF) of rainfall.

• Fire Science and Engineering
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• v.25 no.2
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• pp.9-22
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• 2011

Some Volunteer Fire-Fighting Teams (VFFTs) play an important role in Civilian Volunteer Disaster Prevention by being managed effectively, but the others do not. There can be many cause-analyses about this difference. VFFTs aren't a profit-making organization and are a group which has no compulsion. So it is important that who the leader is, and what type of leadership he has. Furthermore VFFTs have hierarchy like fire-fighting teams and so the leader's command and judgement bring about the actual distinction in the organizational operation. Under this background, the survey has been carried out on the trust of leader and leadership type which may maximize the organization commitment. Consequently, to make efficiency of District Disaster & Volunteer Aid Network increase by augmenting organization commitment. The leader of VFFTs should get the transformational leadership rather than transactional leadership and have paternal or democratic leadership in the decision-making process. Especially we have to create a traditional and unique korean Volunteer fire-fighting organization culture through paternal leadership. Additionally, the trust on leaders should be recognized as a fundamental factor to obtain more performances beyond expectation by increasing the success and output of the team, mutual understanding and cooperation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.34-42
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• 2017

Since existing nonintrusive appliance load monitoring (NIALM) studies assume that voltage fluctuations are negligible for load identification, and do not affect the identification results, the power factor or harmonic signals associated with voltage are generally not considered parameters for load identification, which limits the application of NIALM in the Smart Home sector. Experiments in this paper indicate that the parameters related to voltage and the characteristics of harmonics should be used to improve the accuracy and reliability of the load monitoring system. Therefore, in this paper, we propose an improved NIALM method that can efficiently analyze the types of household appliances and electrical energy usage in a home network environment. The proposed method is able to analyze the energy usage pattern by analyzing operation characteristics inherent to household appliances using harmonic characteristics of some household appliances as recognition parameters. Through the proposed method, we expect to be able to provide services to the smart grid electric power demand management market and increase the energy efficiency of home appliances actually operating in a home network.

• The Korean Nurse
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• v.36 no.3
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• pp.49-69
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• 1997

The urgent needs to establish hospice care systems in Korea arise from the following reasons: 0) a drastic increase in chronically ill patients with the increase of aged population: (2) rapid changes in living environment from the traditional habitation (e. g., Many Koreans living in apartment complexes, which is the most popular form of modern residence in recent years, prefer to die in the hospital.): the overall increase in patients with advanced cancer: (4) recent trends in early discharge of terminally ill patients from the limited hospital facilities to accomodate other medical insurance beneficiaries; (5) easy acceptance of euthanasia owing to the recent social atmosphere that belittles the dignity of human life; (6) medical and nursing care of AIDS patient in terminal stage; (7) and the problem associated with inhumane medical care system, overtreatment, and groundless fears against narcotics. Terminally ill patients were used to be treated in the hospital in the past. In these days, however, they are forced to have home cares with little assistance from the qualified medical personnel because of insufficient hospital facilities, which are even short for the need of emergency patients and provide priority cares to medical insurance beneficiaries with other acute problems. And yet, neither are there any administrative organizations nor systematic medical studies that deal with the level of terminally ill patient's need, their family's problems and resources of hospice care systems in Korea. Thus, most patients are not able to get appropriate medical care at the terminal stage of their lives. The objective of this study is to make comprehensive database for various hospice care organization currently in operation, link them through medical information system, and develop an easily accessible hospice care model that meets the need of most Korean people. Our survey results may be summarized as follows: Nationally there are 40 organizations that provide partial or full hospice care. However, these organizations are not linked to any formal medical service network. Furthermore, the objective of hospice care, care principles, personnel with appropriate training, educational programs, standard for care, costs, consulting service to patients' family members, the extent of medical care from professional staff members, status of hospice facility, and management of those institutions are neither clearly defined nor organized compared to the international hospice care standards. The surveys on patients of terminal stage. grouped in hospice and non-hospice care patients. reveal what they want visiting nursing care to help their pain control. psychological. social and spiritual demands. While the more than 90% of hospice care patients want to reduce their pains. the non-hospice care patients. in addition to their desire for pain control. demanded more psychological. social and spiritual helps as well. The results of this research could be utilized to 0) define the standard of hospice care. (2) provide the guidance for hospice medical care costs. (3) establish the database of hospice care systems. (4) develop softwares. (5) build communication network through Medinet. and (6) provide an organized visiting home nursing care system. These information should be a valuable resource to many medical staffs who are involved in cancer therapy. nursing care. and social welfare programs.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.5
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• pp.1099-1116
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• 2019

Industrial control systems(ICS) are widely used in various industrial area and critical infrastructure. To mitigate security threats on ICS, the security assurance test for industrial control devices has been introduced and operating. The test includes testing of the security function of the device itself and testing of communication robustness. In this paper, we describe the security requirements of EDSA, Achilles, and Korea's TTA standard(security requirements for ICS). And also, we analyzed the characteristics of communication robustness test(CRT) of each certification. CRT verifies the device's operation of essential function while transmitting fuzzing and stress packets. Existing test methods are mostly focused on the embedded devices and are difficult to apply to various devices. We propose a method to test communication robustness which reflect the characteristics of control H/W, control S/W, field devices and network devices in ICS. In the future, we will apply the proposed communication robustness test to actual products and present solutions for arising issues.

• International Journal of Computer Science & Network Security
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• v.21 no.3
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• pp.245-256
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• 2021

Poor logistical infrastructure and agri-food supply chain management leads to significant food waste in logistic system. The concept of the sustainable value added agri-food chains requires defined approach to the analysis of the existing situation, possible improving strategies and also assessment of these changes impact on further development. The purpose of research is to provide scientific substantiation of theoretical and methodological principles and develop practical recommendations for the improvement of the agri-food logistics distribution system. A case study methodology is used in this article. The research framework is based on 4 steps: Value Stream Mapping (VSM), Gap and Process Analysis, Validation and Improvement Areas Definition and Imitation Modelling. This paper presents the appropriateness of LEAN logistics tools using, in particular, Value Stream Mapping (VSM) for minimizing logistic losses and Simulation Modeling of possible logistics distribution system improvement results. The algorithm of VSM analysis of the agri-food supply chain, which involves its optimization by implementing the principles of sustainable development at each stage, is proposed. The methodical approach to the analysis of possible ways for optimizing the operation of the logistics system of the agri-food distribution is developed. It involves the application of Value Stream Mapping, i.e. designing of stream maps of the creation of the added value in the agri-food supply chain for the current and future state based on the minimization of logistic losses. Simulation modeling of the investment project on time optimization in the agri-food supply chain and economic effect of proposed improvements in logistics product distribution system functioning at the level of the investigated agricultural enterprise has been determined. Improvement of logistics planning and coordination of operations in the supply chain and the innovative pre-cooling system proposed to be introduced have a 3-year payback period and almost 75-80% probability. Based on the conducted VSM analysis of losses in the agri-food supply chain, there have been determined the main points, where it is advisable to conduct optimization changes for the achievement of positive results and the significant economic effect from the proposed measures has been confirmed. In further studies, it is recommended to focus on identifying the synergistic effect of the agri-food supply chain optimization on the basis of sustainable development.