• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.91-97
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• 2017

The purpose of this study is to get a more precise frequency of hollow core slabs by comparing the observed values from the actual free vibration tests and the predicted values based on the analysis model. The actual free vibration tests were carried out in the construction field using ${\Omega}$ shaped hollow core slabs. Modal analysis is conducted based on the analysis model that takes into account the differences in section properties due to void parts of slab. The differences between the predicted values based on the modal analysis with analysis model and the measured data from the actual tests range from 2~7%. This study demonstrates that the analysis model that incorporates void parts of slab could be used in evaluating serviceability of hollow core slabs with reasonable accuracies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.27-34
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• 2012

The objective of this study is to evaluate the stiffness of mortar-filled sleeve bar splice using estimation method of failure mode in the sleeve reinforcement splice. To attain this goal, we analyzed the test results of 261 actual-sized mortar-filled sleeve splice specimens. The study results showed that the estimation method of the failure mode in mortar-filled sleeve bar splice made an effective estimate of the stiffness in this bar splice with the exception of specimens with SD500 bars and smooth pipe sleeve. Especially, of the specimens with cast sleeve or uneven pipe sleeve in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, specimens over 98% with SD400 bars and all specimens with SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in monotonic loading. In addition, of the specimens in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, all specimens with SD400 bars and SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in cyclic loading.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.185-196
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• 2006

Fracture toughness is a material property for crack initiation and propagation in fracture mechanics. For mode I fracture toughness measurement in concrete, RILEM committees 89-FMT proposed three-point bend tests based on the two-parameter fracture model. But, there is no proposed test method as a standard for mixed mode test for now. And RILEM three-point bend test procedure is complicate. Therefore, in this study, brazilian disks of various size were designed as the concrete with a similar specified concrete strength and maximum size of coarse aggregate($G_{max}$) were respectively 20mm and 40mm. And mode I fracture toughness of brazilian disks was compared with that of RILEM three-point bend test. As a result, it was suggested appropriate size(thickness, diameter) and notch length ratio of brazilan disk on the $G_{max}$. And it was verified that stress intensity factors for mixed mode can be easily calculated with the disk specimen. Stress intensity factors of a concrete brazilian disk were evaluated with finite element analysis and five terms approximation for comparison.

• Journal of Hydrogen and New Energy
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• v.29 no.6
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• pp.661-667
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• 2018

Electric vehicles are taken a long time to charge and are restricted driving where charging infrastructure was not sufficiently constructed. The vehicle developed to solve these problems is a plug-in hybrid vehicle. It is possible to drive a certain distance by using electric motor and when the battery runs out, it operate the engine. Plug-in hybrid vehicle have a complicated structure and a lot of parts comparing a general vehicle because the electric parts and the internal combustion engine are installed together. Therefore, as the aging (mileage) of the plug-in hybrid vehicle, the influence which change of fuel consumption is expected to be larger than a general vehicle, but an experimental data are lacking. In this paper, we cumulate a mileage of the plug-in hybrid vehicle about 15,000 km and measured the fuel economy when the cumulated distance reached within 160 km, 6,500 km, 15,000 km respectively, by using domestic public test method. For measuring fuel economy of the vehicle, CD mode (driving distance on a single charge) which use only motor and the CS mode which operate motor and combustion engine were measured respectively. As a result, the fuel economy slightly increased at cumulated mileage of 6,500 km compared to the 160 km and the fuel economy of 15,000 km was similar to 160 km.

• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.136-142
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• 2002

In this thesis. we present the cyber lecture system based on XML that uses the communication network as the 100Mbps LAN. The system was designed to analysis the existing cyber lecture system and its details arid to examine web system architecture and XML 3-tier model The result of the study consists of he cyber lecture system based on XML developed on 100Mbps LAN to improve method of the cyber lecture system by using ma 3-tier model arid utilisation of web interface to offer handiness of the cyber lecture system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.7
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• pp.6-11
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• 2012

A mobile station(MS) in an 802.16e network manages its limited energy using the sleep mode operation. An MS can power down its physical operation components during the unavailability interval of the sleep mode. To reduce energy consumption by increasing the unavailability interval, this paper proposes an enhanced power saving mechanism(ePSM) when both activated Type I and Type II power saving classes(PSCs) exist in an MS. A performance evaluation confirms that ePSM results in the improved performance in terms of the unavailability interval as well as the energy consumption than conventional schemes.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.643-645
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• 2004

본 논문은 전력 감소를 위해 사용되는 기법인 Dynamic Power Management를 무선 네트워크 환경에서의 스트리밍 서비스에 적합하게 조정하여 네트워크 인터페이스 카드의 전력 소모를 최소화할 수 있는 기법을 제시한다. 스트리밍 서비스는 Bit Rate이 일정하다는 특징 이 있기 때문에 이를 기반으로 적절한 모드 전환을 한다면 전력의 이득을 취할 수 있다. 본 논문에서는 성능 저하 없이 모드 전환을 하는 시점을 제시하는 Simple DPM 기법과 어느 정도의 성능 저하를 감수하면서 전력이득의 극대화를 취하는 Adaptive DPM 기법을 제시한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10A
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• pp.1695-1705
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• 2001

기존의 셀룰러 IP (CIP : Cellular IP) 프로토콜을 개선하기 위해, 본 논문에서는 각 노드에 통합된 페이징 및 루트 정보관리 캐시(PRC)를 구성하고, 그리고 각 노드 및 이동호스트가 핸드오프-상태모드를 갖는 개선된 셀룰러 IP(ECIP : Enahnced CIP) 프로토콜을 제안하였다. ECIP 프로토콜에 대하여 패킷 유실, 핸드오프 지연 및 네트워크 내 트래픽 부하 특성 등을 고찰한 결과, ECIP는 액세스 네트워크 내 노드와 이동호스트의 수, 노드 내 다운링크의 수, 그리고 네트워크 내 페이징 캐시의 분포비율이 증가할수록 CIP와 비교하여 크게 개선되었다.

• The Journal of the Convergence on Culture Technology
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• v.1 no.4
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• pp.65-69
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• 2015

This study can read register reviews and search read information that users want by musical, drama and movie by using DB by developing App providing the newest culture view and information in android smart phone, when users want to enjoy cultural life. Also, the administrator logins as Administrator-mode and controls cultural information and makes smooth controlling by identifying user's information. In addition, the user logins as User-mode and reads cultural information and can make possible in reading and writing reviews. It makes possible to enjoy leisure activity as cultural activity by identifying reliable performance information via recommendation of friend groups.

• Journal of the Korea Computer Industry Society
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• v.5 no.3
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• pp.393-404
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• 2004

Recently, public home have used a more than two computer connected with network, and several home appliances using independently with internet or network are developing to be related closely with the network. Therefore, the home utilized for a simple terminal of the global network in the past is being expanded to another part of the sub network. For a variety of connecting home-area protocols with the existing existing network, we require a new Residential Gateway(RG) that does not only make the home-area network operating in the sub network but also connects to the external network. In this paper, RG has intrinsic limits against flexible service due to IP address assignment and hardware capacity. In order to solve this problem in the RG, we propose a Management Server(MS). The MS that offers the integrated managements and control services for a variety of devices connected the RG in the home-area. It can not only solve the dynamic IP address assigning problem but also assigns private IP addresses to the home network devices through the Network Address Translation(NAT). It also provides somewhat useful functions for the home network and the RG for other additional services. <중략> The MS is using a SNMP protocol for managing the RG in the domain, a polling method of the MS and the RG compose a sequence polling method, a polling method using a multi-process and a multi-thread. In this paper, we introduce a problem with polling method separately, show a polling method between the MS and the RG using a multi-thread.