• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1327-1332
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• 2015

In this paper, we studied several aspects that affect the quality of VoIP using WiFi network. It's clear that the background data traffic within an AP, the end-to-end delay and the traffic loss of TCP/IP network gives serious effects on the voice quality. A kind of access control for the VoIP connection within an AP should be done for the acceptable voice quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2405-2410
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• 2012

The 4th generation mobile communication system, LTE, does not support an additional core network to provide voice service, and it is merged into a packet network based on all IP. Although Voice service over LTE can be supported by VoIP, it will be provided by the existing 3G networks because of the discontinuity of LTE coverage. However, it is inevitable to adopt VoIP over LTE to provide high quality voice service. In this paper, we investigate the capacity of VoIP over LTE. Our results indicate that spectral efficiency can be significantly improved as channel bandwidth increases in terms of VoLTE capacity. In addition, we can achieve higher VoLTE capacity without decreasing control channel capacity.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.350-353
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• 2004

The increasing use of Ethernet-TCP/IP network in industry has led to the growing interest in its reliability in real-time applications such as automated manufacturing systems and process control systems. However, stochastic behavior of its medium access scheme makes it inadequate for time-critical applications. In order to guarantee hard real-time communication service in Ethernet-TCP/IP network, we proposed an algorithm running over TCP/IP protocol stack without modification of protocols. In this paper, we consider communication services guaranteeing deadlines of periodic real-time messages over MAC protocols that have unbounded medium access time. We propose a centralized token scheduling scheme for multiple access networks. The token is used to allow a station to transmit its message during the time amount that is appended to the token. The real-time performance of the proposed algorithm has been described.

• International journal of advanced smart convergence
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• v.6 no.2
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• pp.1-8
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• 2017

Recently, the development of the information communication industry has made many changes in the industrial acoustic industry. Especially, it has a great influence on the change of system and equipment of acoustic system. Analog equipment is changing to digital equipment, and integrated control equipment makes it easier to operate and manage the sound system. However, the integrated control system currently on the market is only controllable for some devices. In this paper, we propose a new AoIP - based system configuration method, which enables the operation status monitoring, unmanned operation and self - diagnosis of equipment. As a result of the study, it is confirmed that the proposed system can be operated, monitored, and self - diagnosed at remote sites. It is expected that an AoIP- based sound system will be the industry standard in the future.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.5
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• pp.29-38
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• 2002

This paper presents IPv6, ATM, and IP/ATM security systems for computer network. IPv6 uses authentication header and ESP to provide security services. Authentication header provides integrity and authentication services and ESP provides integrity, authentication and confidentiality services. User plan of ATM provides authentication, integrity, confidentiality and access control services and control plan of ATM provides authentication and integrity services. IP/ATM security services are also presented.

• Journal of Korean Academy of Nursing
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• v.36 no.8
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• pp.1301-1307
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• 2006

Purpose. To determine the effects of provision of information on mother's problem focused coping ability during their child's intravenous procedure. Methods. Data were collected from 56 mothers whose children have admitted to pediatric ward in the hospital. The participants included 27 intervention group mothers and 29 control group mothers. For the information intervention, 'Programmed Information for Parental Coping before Intravenous Procedure (PIPC- IP)', video program was made based on self-regulation theory for the experimental group mothers. Mother's coping ability was measured by parental supportive behavior, parental beliefs and Profile of Mood State (POMS). Results. Mothers who received PIPC-IP showed significantly higher levels of supportive behavior (t = 3.55, p = .005) and Parental Beliefs (t = 2.95, p = .005), but no significant difference in negative mood on POMS (t = .15, p = .87) compared to mothers in the control group. Conclusions. These results demonstrate that PIPC-IP is an effective intervention to increase the supportive behaviors and beliefs of mothers' problem focused coping ability but not the negative mood.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.80-83
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• 1999

The windup phenomenon appears and results in performance degradation such as large overshoot, slow settling time when the integral-proportional (IP) controller output is saturated. An anti-windup IP controller is proposed to improve the control performance for the motor drives. The proposed algorithm is applied to the current control of a vector-controlled induction motor driven by a pulse width modulated(PWM) voltage-source inverter. The integral state is separately controlled corresponding to whether the IP controller output is saturated or not. The experimental results show that the current response has much improved performance such as little overshoot and fast settling time.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.223-226
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• 2003

In this paper, we propose new agent discovery and route discovery schemes to support Mobile IP (MIP) in Ad Hoc networks with wireless backbone. The wireless backbone consisting of stationary wireless routers and Internet gateways (IGs) is a kind of wireless access network of IP-based core network. The proposed scheme utilizes favorable features of wireless backbone such as stable links and no energy constraints. In the agent discovery scheme, backbone-limited periodic Agent Advertisement (AA) and proxy-AA messages are used, which reduce network-wide broadcasting overhead caused by AA and Agent Solicitation messages and decentralize MIP processing overhead in IGs. In order to reduce delay time and control message overhead during route discovery far the destination outside Ad Hoc network, we propose a cache-based scheme which can be easily added to the conventional on-demand routing protocols. The proposed schemes can reduce control overhead during agent discovery and route discovery, and efficiently support MIP in Ad Hoc network with wireless backbone.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.716-722
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• 2001

This paper has defined the 3G and beyond wireless networks as the one that is based on IP network architecture and proposed the congestion control scheme in the access networks. Basically the proposed method is built on the ECN(Explicit Congestion Notification) and utilizing the advantages of the wireless and I networks in broadcasting packet in their access network. Consequently it provides the efficiency in controlling the congestion that can be happened by the mobility support in the future wireless networks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.1115-1122
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• 2012

VoIP service is steadily growing due to the spread of smartphones, enhanced network, and various VoIP applications. But, VoIP has many security vulnerabilities because it is based on IP network. This paper analyzes the important weight of VoIP security checklists for incident prevention and response using AHP. The results of AHP analysis showed that network security, incident response, and access control were the most important in technical, administrative, physical standpoint. This study proposes factor analysis of VoIP security checklist at first time. By doing this, it will be used helpfully when VoIP service providers establish their own security policies and inspect their VoIP environment according to their security policies.