• Journal of Advanced Marine Engineering and Technology
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• v.26 no.6
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• pp.631-637
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• 2002

Two stroke low speed diesel engines are used as a power supplier not only for marine vessel but also diesel power plant with a benefit of its higher mobility and durability than the other thermal engines. However, there are some disadvantages such as the bigger vibrating excitation forces generated by high combustion pressure in cylinders which various kinds of vibrations are caused. In this paper, it is theoretically studied to control engine body vibration using dynamic vibration absorber. As an actual case, dynamic absorbers are designed for controlling X-mode vibration of 9K80MC-S engine on the diesel power plant and its performance is identified by the vibration test both in shop and site

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.264-273
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• 2012

The purpose of this study was to determine the test-retest reliability and the concurrent validity between tinetti mobility test (TMT), berg balance scale (BBS) and space balance 3D which is one of the computerized measurement and visual feedback balance assessment system in subacute stroke patients. Twenty three ambulatory acute stroke subjects were measured the TMT, BBS and space balance 3D. The test-retest reliability(intra-class correlation coefficient: ICC) indicated that the static and dynamic balance in space balance 3D considered moderate reliability and TMT, BBS were good reliability. In case of concurrent validity, there were moderate validity (p<.01) between static balance test with space balance 3D and each TMT, BBS. But there were only poor validity (p<.05) between center to forward-left, center to backward-left phase in dynamic balance test with space balance 3D and each TMT, BBS. These findings suggest that in subacute stroke patients the test-retest reliability and concurrent validity using the space balance 3D and TMT were valuable in balance test but there was limitation to evaluate dynamic balance test.

• Journal of Korea Multimedia Society
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• v.4 no.2
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• pp.161-170
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• 2001

Mobility management technology is one among the most important issues in future mobile communication systems. The mobility management technology includes location management and handoff technologies. In this paper, we present a hierarchical distributed dynamic location management scheme that is compatible with the IMT-2000 environment. The proposed scheme composes a cluster with location registers, then makes up a hierarchical structures consisting of clusters. Each layer in the hierarchical structure uses different location management strategies cooperating another layers with each other. Also, the proposed scheme uses location update algorithm considering the frequency of location queries from nodes outside the local cells. We evaluate the performance of the proposed scheme through an analytical model.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.736-741
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• 2005

The highly popular algorithm to determine routing path for the multi-hopping wireless sensor network is DSR(Dynamic Source Routing), which is one of the Demand-Driven way to makes the route only when there is a request for sending data. However, because DSR attaches the route's record on the sending packet, the bigger number of sensor node is, the heavier packet in DSR becomes. In this paper, we try to propose the new optimal routing path selecting algorithm which does not make the size of packet bigger by using proper routing table even though the number of sensor node increases, and we try to show our algorithm is more stable and reliable because it is based on the cost function considering some network resources of each sensor node such as power consumption, mobility, traffic in network, distance(hop) between source and destination.

• Journal of Communications and Networks
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• v.13 no.6
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• pp.583-590
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• 2011

Full-mesh IPSec tunnels pass through a black ("unsecure") network (B-NET) to any red ("secure") networks (RNETs). These are needed in military environments, because they enable dynamically changing R-NETs to be reached from a BNET. A dynamically reconfiguring security policy database (SPD) is very difficult to manage, since the R-NETs are mobile. This paper proposes advertisement process technologies in association with the tunnel gateway's protocol that sends 'hello' and 'prefix advertisement (ADV)' packets periodically to a multicast IP address to solve mobility and security issues. We focus on the tunnel gateway's security policy (SP) adaptation protocol that enables R-NETs to adapt to mobile environments and allows them to renew services rapidly soon after their redeployment. The prefix ADV process enables tunnel gateways to gather information associated with the dynamic changes of prefixes and the tunnel gateway's status (that is, 'down'/restart). Finally, we observe two different types of performance results. First, we explore the effects of different levels of R-NET movements on SP adaptation latency. Next, we derive the other SP adaptation latency. This can suffer from dynamic deployments of tunnel gateways, during which the protocol data traffic associated with the prefix ADV protocol data unit is expected to be severe, especially when a certain tunnel gateway restarts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.1-9
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• 2009

In this paper, we propose an enhanced handoff support scheme based on network-based mobility management protocol, Proxy Mobile IPv6 (PMIPv6), which is actively standardized by the IETF NETLMM working group. By utilizing the dynamic virtual hierarchy network architecture between mobile access gateways (MAGs), the proposed scheme can support network scalability and reliability to wireless access network. In addition, we propose pre-authentication process based on the policy store (PS) to support a fast and seamless handoff. We evaluate the performance of the proposed scheme in terms of handoff delay and end-to-end delay thru computer simulation. Thru, various computer simulation results, we verified the superior performance of the proposed scheme by comparing with the results of other schemes.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.1-8
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• 2008

If a sink can move in sensor networks, the routing change can be more occur. If the sink has the mobility, it moves in sensor network area so that the connection between the sink system and sensor nodes will be changed continuously. Hence, the overhead can occur cased by the many routing changed. Therefore, the dynamic routing scheme is needed to support the mobile sink connection. In this paper, we propose the previous connection assignment scheme. The mobile sink can have low cost overhead from calculating dynamic rerouting that it determines the new virtual path before the physical path setup.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1342-1349
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• 2010

Full-mesh IPSec tunnels, which constitute a black network, are required so that the dynamically changing PT (Plain Text) networks can be reachable across the black network in military environments. In the secure and mobile black networks, dynamically re-configuring IPSec tunnels and security policy database (SPD) is very difficult to manage. In this paper, for the purpose of solving mobility and security issues in military networks, we suggest the relating main technologies in association with DMIDP (Dynamic Multicast-based IPSec Discovery Protocol) based on existing IPSec ESP (Encapsulating Security Payload) tunnels and IPSec key managements. We investigate the main parameters of the proposed DMIDP techniques and their operational schemes which have effects on mobility and analyze operational effectivemess of the DMIDP with proposed parameters.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.606-609
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• 2015

Lawful Interception (LI)이란 합법적인 형태의 통신내용 및 관련 정보의 수집활동을 말한다. 최근의 4G LTE 기반의 이 기종 통신망에서의 합법적 감청은 전통적인 유선 및 3G 네트워크 중심의 감청기법 이외의 새로운 기법과 표준이 필요한 실정이다. 특히, LTE와 같이 User Equipment (UE)가 네트워크상에서 핸드오버를 통해 자유롭게 이동하거나, 3G와 같은 이 기종 망에서의 연결을 포함한 다른 사업자의 새로운 지역에서의 네트워크 연결이 보장되는 형태의 환경에서의 연속적 감청을 보장하는 것은 합법적 감청분야의 중요한 이슈중의 하나이다. 따라서, 본 논문에서는 국내의 4G-LTE망을 중심으로 기존의 3G 망을 자유롭게 이동하는 네트워크 도메인과 IMS/SIP 기반의 서버의 연속성을 보장하는 서비스 도메인 영역에서의 합법적 감청 기법을 제안한다. 본 논문에서 제안하는 기법은 이 기종 무선망과 유선망이 혼재된 네트워크에서의 IMS/SIP 기반 서비스의 이동성을 감지하여 합법적 감청의 연속성을 보장하기 위한 기법을 포함하고 있다.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.1
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• pp.25-33
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• 2017

PURPOSE: The initiation of the trunk muscles in stroke patients is delayed because the muscles involved in reach arm are activated earlier than the trunk muscles. The objective of this study was to examine the effects of mobility, balance, and trunk control ability through selective trunk exercise (STE) in patients with chronic stroke. METHODS: A randomized pre-test and post-test control group design was initially used, with subjects randomly assigned to the STE group (n=15) and a control group (n=14). All groups underwent physical therapy based on the neuro-developmental therapy (NDT) for 30 minutes a day, five times per week for four weeks. Additionally, the STE group did the trunk exercise for 30 minutes a day, three times per week for four weeks. The timed up and go test (TUG), Berg balance scale (BBS), and trunk impairment scale (TIS) were used for assessment. RESULTS: The scores of the TUG, BBS, dynamic sitting balance subscale, and coordination subscale of TIS improved significantly in both groups but the improvement was more pronounced in the STE group (p<.05). This study showed a large effect on the scores of the TIS coordination subscale (d=.93) (p<.05), TIS dynamic balance subscale (d=.81) (p<.05), TUG (d=.75) (p<.05), and BBS (d=.73) (p<.05). CONCLUSION: The combined STE and NDT program showed improvements in measures of mobility, balance, and trunk control in chronic stroke patients. These results suggest that STE should be considered to be included in the treatment program for patients with chronic stroke.