• Journal of KIISE:Computer Systems and Theory
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• v.35 no.6
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• pp.293-303
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• 2008

As the computing environment moves to the wireless and handheld system, the power efficiency is getting more important. That is the case especially in the embedded hand-held system and the power consumed by the memory system takes the second largest portion in overall. To save energy consumed in the memory system we can utilize low power mode of SDRAM. In the case of RDRAM, nap mode consumes less than 5% of the power consumed in active or standby mode. However hardware controller itself can't use this facility efficiently unless the operating system cooperates. In this paper we focus on how to minimize the number of active units of SDRAM. The operating system allocates its physical pages so that only a few units of SDRAM need to be activated and the unnecessary SDRAM can be put into nap mode. This work can be considered as a generalized and system-wide version of PAVM(Power-Aware Virtual Memory) research. We take all the physical memory into account, especially buffer cache, which takes an half of total memory usage on average. Because of the portion of buffer cache and its importance, PAVM approach cannot be robust without taking the buffer cache into account. In this paper, we analyze the RAM usage and propose power-aware page allocation policy. Especially the pages mapped into the process' address space and the buffer cache pages are considered. The relationship and interactions of these two kinds of pages are analyzed and exploited for energy saving.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.149-160
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• 2015

This study reports the interfacial bond strength between Ultra High Performance Concrete (UHPC) and Normal Strength Concrete (NSC). While previous studies have focused on the interfacial strength between NSC substrate and UHPC overlay, this study use precast UHPC for enhanced constructability and replacement of formwork. The factors affecting the interface strength are comprehensively reviewed. It can be classified into: interface shape, degree of hardening and moisture condition of UHPC before combining with NSC, and curing condition of composite materials. Conducted experiments verify the effects of each factor on the interface strength and, accordingly show different failure modes. In particular, a new failure mode of the failure of a part of UHPC was firstly found in the case of sample with rough interface between UHPC and NSC. The other factors of the degree of hardening and the moisture and curing conditions of UHPC were discussed. This research will provide a valuable foundation to utilize the UHPC as a composite material.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.11-20
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• 2014

This paper aims at comparing and analyzing shear buckling characteristics between sinusoidal corrugation shape and trapezoidal one. For this, I adopted the equal-length trapezoidal corrugation and sinusoidal one for the analytical models, and analyzed their shear buckling characteristics through linear buckling analysis and on its theory. Generally, the shear buckling shapes of corrugated steel plates are classified into local buckling, global buckling, and interactive buckling from the two buckling modes. Sinusoidal corrugation shape, unlike trapezoidal corrugation, does not have flat sides, which causes another tendency in shear buckling mode. Especially, the changes and different aspects of shear buckling on the boundary between local buckling and global buckling appear in different corrugation shapes. According to the analysis results, interactive buckling mode appeared on the boundary of local buckling and global bucking in trapezoidal corrugation. However, in the case of corrugated steel plates with sinusoidal configuration, interactive buckling mode appeared in the part where global bucking takes place. Besides, trapezoidal shapes are of advantages on shear buckling resistance in the local buckling section, and so are sinusoidal shapes in the global buckling section.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.558-564
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• 2007

3G Long Term Evolution, which aims for various mobile multimedia service provision by enhanced wireless interface, proposes VoIP-based voice service through a Packet Switching (PS) domain. As delay and loss-sensitive VoIP traffic flows through the PS domain, more challenging technical difficulties are expected than in Circuit Switching (CS) domain based VoIP services. Moreover, since 3G LTE, which adopts the OFDM as its physical layer, introduces Physical Resource Block (PRB) as a unit for transmission resources, new types of resource management schemes are needed. This paper proposes a PRB scheduling algorithm of MAC layer for VoIP service in 3G LTE and shows the simulation results. The proposed algorithm has two key parts; dynamic activation of VoIP priority mode to satisfy VoIP QoS requirements and adaptive adjustment of the priority mode duration in order to minimize the degradation of resource utilization.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.235-242
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• 2011

The control performance in active structural control system can be drastically deteriorated when the modeling errors and the uncertainties existing in the disturbances are disregarded in the designing stage. It can even throw the control system into an unstable phase, resulting in out of control against the seismic excitations. The purpose of the study is to investigate the control effectiveness of a non-linear control system called sliding mode controller(SMC) in cooperation with a Tuned Mass Damper subjected to the three seismic excitations selected from the FFT analysis. Even though the transient performance such as settling time and overshoot were deteriorated, the robustness against the system stability was appeared from SMC when the structural masses and stiffness perturbed within the range of ${\pm}30%$. SMC is a feasible technique for active structural control in cooperation with TMD against seismic disturbances, exhibiting robustness in perturbation of system stiffness and mass as well as uncertainties of the disturbances.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.293-296
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• 2006

무선 인터넷의 급속한 성장에 힘입어, 사용자들은 다양한 무선 인터넷 환경을 통해 멀티미디어 서비스 등의 IP 서비스에 보다 쉽게 접근할 수 있게 되었다. IP 기반의 네트워크 통합을 도모하는 4G 네트워크에 대한 관심이 증폭되면서, 이러한 다양한 무선 네트워크 환경을 어떻게 통합하여 관리할 것인가에 초점이 맞추어져 왔다. 이에, 이종 네트워크를 지원하는 다중 모드 단말의 이동성 관리를 보장하기 위한 공통 접속 모듈(CCM: Common Connection Module)이 제안되었다. 본 논문에서는, 공통 접속 모듈을 기반으로 동작하는 이동 단말들의 관리와 더불어, 이종 네트워크 상에서 단말의 이동성을 제어할 수 있는 네트워크 관리 시스템인 Network Controlled Mobility Management System (NCMMS)을 소개한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.478-480
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• 2004

네트워크의 발달로 인하여 지역적으로 원거리에 위치한 다수의 사용자들이 공동 작업을 수행할 수 있는 다양한 기술들이 개발되었다. 공동작업을 지원하는 협업시스템은 HTTP 프로토콜을 사용하거나 또는 각자의 고유한 통신 프로토콜들을 정의하여 구현하였다. 이러한 방법은 협업시스템 간의 상호 운용성이 결여되는 문제를 발생시켰다. W3C의 IETF에서는 협업지원을 위한 WebDAV 명세가 발표되었다. WebDAV는 웹상의 공동 저작활동을 지원하기 위한 표준프로콜로서, 원거리에 있는 사용자들 간에 인터넷상의 파일을 편집하고 관리할 수 있도록 해주는 HTTP의 확장이다. 이를 이용하여 협업시스템을 구성하면 협업시스템 간의 상호 운용성을 높일 수 있을 것이 다. 협업시스템의 클라이언트는 협업지원 서버의 자원들을 효율적으로 이용할 수하고 팀원들 간의 상호작용이 원활 하게 이루어 져야한다. 이러한 요구 조건을 고려하여 본 논문에서는 WebDAV 프로토콜을 이용한 협업시스템의 클라이언트를 설계하였다. 고급기능으로 사용자가 협업지원 서버의 파일을 편집할 때 자동으로 저작프로그램을 연결하고 저작프로그램을 종료할 때 파일의 변화된 내용과 파일의 버전관리를 실시간으로 서버에 적용될 수 있게 디자인하였다. 또한 드래그앤드롭(Drag & Drop)을 통한 파일이동을 지원하고 파일의 읽기모드와 쓰기모드를 지원하는 기능을 설계하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.163-170
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• 2011

A concept of Modular GFRP(Glass Fiber Reinforced Polymer) deck panel was proposed for bridge decks. The modular GFRP bridge deck system is comprised of main unit module and connector unit module with GFRP flanges and web. Its structural performance under static loading was evaluated and compared with the LUSAS finite element predictions. It was found that the presented GFRP modular panel was very efficient for use in bridges. The failure mode of the proposed GFRP deck was similar when compared with that of commercial other GFRP decks developed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.147-156
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• 2003

In this paper, a damage detection method using mode shapes of truss structures is presented. The theory is formulated based on the changes in the modal strain energy in a truss type structures due to damage. To examine the feasibility, the theory is applied to an experimental data of a 1:6 scale model of a typical hexagonal truss structure. The experiment consists of 17 damage scenarios subjected to three different types of damage. The damage evaluation results show that the proposed method detects successfully damage in truss elements and also show that the performance of proposed method can be significantly impacted by the noise in the measurement data for small damage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.156-165
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• 2009

This study is to consider the character of cables in six World-Cup stadiums constructed in 2002 and to inspect problems on measurement natural frequencies interpretation and application of existing theory. The results of the experiment were shown that it was possible to determine the tension force of the real cables with an accuracy of 8% by taking the cable bending stiffness. But for the range of cable affected greatly by bending stiffness(${\xi}{\leq}7$), it was appeared the tendency to increase estimated error and was considered to need additional study of this range. Estimated tension error could not be improved so much in comparison to the case using single mode of vibration even through multiple modes of vibration were used.