• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.911-918
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• 2002

An important issue in the design of future Personal Communication Service (PCS) networks is the efficient management of location information. In this paper, we propose an adaptive distributed dynamic location management algorithm that stores the position of the mobile terminal in k of the n location information databases (LIDs). The proposed algorithm chooses adaptively k. replication factor according to both the space locality of LIDs in wireless mobile networks and the location query popularity to local mobile terminal from remote mobile terminals. The performance of proposed algorithm is evaluated by both an analytical model and a simulation. Based on the results of performance evaluation, we know that the performance of the proposed algorithm is better than that of Krishnamurthi's algorithm regardless of call-mobility ratio.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.51-60
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• 2008

Micro-mobility protocols have been developed to reduce the control message overhead due to movements of mobile nodes. With the spread of mobile devices, services using mobile nodes are increasing and multicast services are becoming more important in providing multimedia services. In this paper we propose a new multicast protocol suitable for micro-mobility environments. The proposed protocol is designed to maintain optimal multicast routing paths and continue to provide multicast services without disruption in spite of frequent handoffs due to movements of mobile nodes. We used simulation to evaluate the proposed protocol, compared its performance with existing multicast protocols for mobile environments including bi-directional tunneling, remote subscription, and MMA, and observed that the proposed protocol exhibited better performance in terms of transmission success ratio and overhead on the network.

• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.355-366
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• 2003

Today's market share of mobile internet service is growing rapidly in internet due to the rapid advances in wireless mobile networks. To guarantee for QoS of Mobile Nodes in wireless mobile networks, we propose the Proxy MRSVP (PMRSVP) which is efficient resource reservation protocol. The PMRSVP using a modified regional registration restrains excessive message generation from existing protocols that propose an alternative plan of existing best effort service in wireless mobile networks. We show that signaling message generation quantities and resource registration costs of the PMRSVP are lower than MRSVP and Hierarchical MRSVP (HMRSVP) because as Mobile Agent (MA) plays a proxy role instead of Corresponding Host (CH). We evaluate resource reservation cost with registration cost of intradomain and interdomain of the proposed method in the paper by comparing to that of the MRSVP and HMRSVP.

• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.109-118
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• 2010

Proxy mobile IPv6 (PMIPv6) protocol is a network-based mobility management protocol to support mobility for IPv6 nodes without host involvement. In PMIPv6, the Mobile Access Gateway (MAG) incurs a high signaling cost to update the location of a mobile node to the remote Local Mobility Anchor (LMA) if it moves frequently. This increases network overhead on the LMA, wastes network resources, and lengthens the delay time. Therefore, we propose a new mobility management scheme for minimizing signaling cost using the pointer forwarding. Our proposal can reduce signaling costs by registration with the neighbor MAG instead of the remote LMA using the pointer forwarding. The cost analysis using imbedded Markov chain presented in this paper shows that our proposal can achieve performance superior that of PMIPv6 scheme.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.335-346
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• 2009

Mobile environments are evolving the main communication environment as a develops of communication technology. In mobile environments, sensitive information can be compromised on-line, so demand for security has increased. Also, mobile devices that provide various services are in danger from malware and illegal devices, phishing and sniffing etc, and the privacy. Therefore, MTM(Mobile Trusted Module) is developed and promoted by TCG(Trusted Computing Group), which is an industry standard body to enhance the security level in the mobile computing environment. MTM protects user privacy and platform integrity, because it is embedded in the platform, and it is physically secure. However, a security approach is required when secret data is migrated elsewhere, because MTM provides strong security functions. In this paper, we analyze the TCG standard and migration method for cryptographic key, then we propose a secure migration scheme for cryptographic key using key Backup/Recovery method.

• The KIPS Transactions:PartC
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• v.19C no.1
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• pp.29-38
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• 2012

Due to rapid spread of smart phones and SNS(Social Network Service), using of Internet applications has increased and taking up bandwidth more than 3G network's capacity recently. This caused reduction of speed and service quality, and occurred strong needs that backbone network company to increasing investment costs. Also a great rise of mobile network users causing identity management problems on mobile service provider through mobile network. This paper proposes advanced IDM3G[1] - to solve user ID management and security problems on mobile internet application services over 3G network and more - authentication management protocol. $I^2DM$ protocol breakup loads which made by existing IDM3G protocol's mutual authentication via mobile operator, via sending some parts to internet application service provider, enhancing mobile and ID management of service provider and network load and process load from information handling and numbers of transmitting packets, to suggest more optimized protocol against further demanding of 3G mobile network.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.163-166
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• 2002

컴퓨터 게임의 발달은 오프라인 PC 게임에서 인터넷의 보급으로 인해 온라인 게임으로 발전하였다. 그 후 인터넷 환경은 유선 환경뿐만 아니라 무선 환경에서도 무선 단말기를 이용하여 게임 서비스가 가능한 수준에 이르렀다. 그러나 적은 메모리와 낮은 수준의 처리능력을 가지고 있는 제한적인 모바일 환경의 특성으로 유선 인터넷에서와 같이 멀티미디어를 포함한 다양한 형태의 정보제공 및 인터렉티브한 모바일 게임이 어려운 현실이다. 본 논문에서는 WAP(Wireless Application Protocol)을 기반으로 하여 다운로드 솔루션을 채택한 GVM(General Virtual Machine) 상에서 실행될 수 있는 모바일 게임을 설계하고 MobileC 언어를 사용하여 제작하였다. 또한, 모바일 게임을 설계하고 제작하는 과정을 통해서 단말기의 제한적인 실행환경에서 최대한의 효과를 나타낼 수 있는 개발 모델을 제시하고자 한다. GVM은 무선 단말기 상에서 동적인 응용프로그램을 실행할 수 있는 가상기계 플랫폼이다.

• ETRI Journal
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• v.19 no.3
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• pp.242-258
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• 1997

The Qualcomm code excited linear prediction (QCELP) speech coder was adopted to increase the capacity of the CDMA Mobile System (CMS). In this paper, we implemented the QCELP speech coding algorithm by using TMS320C50 fixed point DSP chip. Also the fixed point simulation was done with C language. The computation complexity of QCELP on TMS320C50 was 10k words and data memory was 4k words. In the normal call test on the CMS, where mobile to mobile call test was done in the bypass mode without double vocoding, mean opinion score for the speech quality was he Qualcomm code excited linear prediction (QCELP) speech quality was 3.11.

• Annals of Clinical Neurophysiology
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• v.5 no.1
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• pp.16-20
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• 2003

Background: Mobile phone has become a very popular device used in everyday our lives. However, the possible hazard to human body such as brain tumor has been proposed intermittently. This unwanted possibility was calmed down due to the absence of definite evidence of hazard. This study was performed to see the effect of mobile phone use on the brain temperature. Methods: In 20 volunteers, we performed 4 steps of temperature measuring procedure. Four steps are pre-use (S1, basal state), wire-phone (S2, conventional telephone), PCS phone (S3, using 1,750~1,900 MHz), cellular phone (S4, using 820 MHz) states. Brain temperatures were measured by radiothermometer at 10 sites (5 sites in each hemisphere) of the brain after 5minutes of telecommunication through the phones. The final data were compared using paired t-test. Results: In PCS phone user group (Average; $35.73708^{\circ}C$), brain temperature decreased (with statistical significance, p<0.05), compared to those of non-user group (Average; $35.9527^{\circ}C$) or conventional wire phone user group. In cellular phone user group (Average; $35.82155^{\circ}C$), brain temperature decreased slightly (without statistical significance, p>0.05) compared to those of non-user group (Average; $35.9527^{\circ}C$) or conventional wire phone user group (Average; $35.922^{\circ}C$). The temperature change was not limited to the mobile phone applied side but on both hemisphere of the brain. Conclusion: In conclusion, mobile phone (especially PCS phone) decreased brain temperature in both hemispheres without side-to-side temperature difference. In addition, this study suggests possibility of radiothermometer application to the study of electromagnetic wave effect and protection method research in the future.

• Journal of the Korea Society of Computer and Information
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• v.23 no.10
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• pp.119-125
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• 2018

The purpose of this study was to investigate the effect of health care on the body composition and metabolic Syndrome risk factors in male office workers. The subjects of this study were 30~40's male office workers and their physical activities were increased by mobile healthcare. The date analysis in this study was carried out paired t­test using SPSS 20.0 version(${\alpha}=.05$). The result of study were as follow: First. body composition kg(p<.015), BMI(p<.041), WC(p<.026) were significantly decreased after Increase in Physical Activity Using Mobile Health Care, although these did not reach statistical significance, SMM(p<.123), BF(p<.059) was slightly increased and decreased trend. Second, SBP(p<.300), DBP(p<.384) was slightly decreased trend and BS(p<.034) were significantly decreased after Increase in Physical Activity Using Mobile Health Care, Third, plasma TC(p<.015), TG(p<.003), LDL-C)(p<.000) were significantly decreased after Increase in Physical Activity Using Mobile Health Care and plasma HDL-C (p<.003) were significantly increased. These results suggest that increased physical activity using mobile health care has a positive effect on the body composition and metabolic syndrome index in male office workers. Sedentary lifestyles could be changed by Continuous feedback using mobile healthcare.