• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.56-66
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• 2009

In the traditional Server/Client architecture, the client connects to the known servers and gets information through web searching. However, nowadays, diverse internet devices providing services (get) working on internet easily. The update interval of the services or information provided by the devices is relatively short. And also they tend to be both a server and a client. In this situation, the way of the traditional information searching such as web searching is not appropriate. In this paper we propose a service push model, where it pushes its service profiles to all the other network devices by broadcasting them on the network. When a device connects to the network newly, it can get all service profiles in the network and it gets service profiles newly pushed by service providers in prompt. Also it can call any service among the service profiles within itself. We implemented a prototype system for the service push model on the JXTA platform based on P2P network. Also we measured the service profile pushing delay, the service discovery time, and the response time of service execution by running test applications written on the prototype system.

• Steel and Composite Structures
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• v.42 no.4
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• pp.477-487
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• 2022

The shear stiffness of headed-stud shear connectors has no unified definition due to the nonlinear characteristics of its load-slip relationship. A unified framework was firstly adopted to develop a general expression of shear load-slip equation for headed-stud shear connectors varying in a large parameter range based on both force and energy balance. The pre- and post-yield shear stiffness were then determined through bilinear idealization of proposed shear load-slip equation. An updated and carefully selected push-out test database of 157 stud shear connectors, conducting on studs 13~30mm in diameter and on concretes 30~180 MPa in cubic compressive strength, was used for model regression and sensitivity analysis of shear stiffness. An empirical calculation model was also established for the stud shear stiffness. Compared with the previous models through statistical analysis, the proposed model demonstrates a better performance to predict the shear load-slip response and stiffness of the stud shear connectors.

• Steel and Composite Structures
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• v.10 no.4
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• pp.317-329
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• 2010

According to the results of 9 circular concrete filled steel tube (CFT) push-out tests, a new theoretical model for average bond stress versus free end slip curve is proposed. The relationship between verage bond stress and free end slip is obtained considering some varying influential parameters such as slenderness ratio and diameter-to-thickness ratio. Based on measured steel tube strain and relative slip at different longitudinal positions, the distribution of bond stress and relative slip along the length of steel tube is obtained. An equation for predicting the varying bond-slip relationship along longitudinal length and a position function reflecting the variation are proposed. The presented method can be used in the application of finite element method to analyze the behavior of CFT structures.

• Journal of Korean Association for Spatial Structures
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• v.15 no.2
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• pp.69-77
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• 2015

Ultra High Performance Fiber Reinforced Concrete (UHPFRC) has a outstanding tensile hardening behaviour after a crack develops, which gives ductility to structures. Existing shear strength model for fiber reinforced concrete is entirely based on crack opening behavior(mode I) which comes from flexural-shear failure, not considering shear-slip behavior(mode II). To find out the mode I and mode II behavior on a crack in UHPFRC simultaneously, maximum shear strength of cracked UHPFRC is investigated from twenty-four push-off test results. The shear stress on a crack is derived as variable of initial crack width and fiber volume ratio. Test results show that shear slippage is proportional to crack opening, which leads to relationship between shear transfer strength and crack width. Based on the test results a hypothesis is proposed for the physical mechanics of shear transfer in UHPFRC by tensile hardening behavior in stead of aggregate interlocking in reinforced concrete. Shear transfer strength based on tensile hardening behavior in UHPFRC is suggested and this suggestion was verified by comparing direct tensile test results and push-off test results.

• Journal of Power Electronics
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• v.14 no.3
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• pp.444-457
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• 2014

This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with $k_i$ and $R_L$ as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of $R_L$ and the operating point of the PV simulator to match the controller parameters with $R_L$. The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.

• The Journal of Information Systems
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• v.27 no.2
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• pp.221-245
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• 2018

Purpose This study aims to investigate the factors that influence switching intention of Smart Appliances. We focuses on Push-Pull-Mooring theory and status quo bias as factors related to switching behavior. Design/methodology/approach This study developed an model to explain the switching intention of Smart Appliances and conducted structural equation modeling with AMOS22.0. To test the proposed hypotheses, we collected 319 survey responses from smart appliances's users. Findings The results indicated that low usefulness and low ease of use had an effect on the switching intention of smart appliances. The results also indicated that attractiveness of the alternative and social norms had an effect on the switching intention of smart appliances. Lastly, The difference between the relation of push effect and switching intention and the relation of pull effect and switching intention was found to be due to the level of status quo bias. The academic and managerial implications were discussed based on the results of empirical analysis.

• Steel and Composite Structures
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• v.25 no.1
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• pp.79-92
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• 2017

Initial damage to a stud due to corrosion, fatigue, unexpected overloading, a weld defect or other factors could degrade the shear capacity of the stud. Based on typical push-out tests, a FEM model and theoretical formulations were proposed in this study. Six specimens with the same geometric dimensions were tested to investigate the effect of the damage degree and location on the static behavior and shear capacity of stud shear connectors. The test results indicated that a reduction of up to 36.6% and 62.9% of the section area of the shank could result in a dropping rate of 7.9% and 57.2%, respectively, compared to the standard specimen shear capacity. Numerical analysis was performed to simulate the push-out test and validated against test results. A parametrical study was performed to further investigate the damage degree and location on the shear capacity of studs based on the proposed numerical model. It was demonstrated that the shear capacity was not sensitive to the damage degree when the damage section was located at 0.5d, where d is the shank diameter, from the stud root, even if the stud had a significant reduction in area. Finally, a theoretical formula with a reduction factor K was proposed to consider the reduction of the shear capacity due to the presence of initial damage. Calculating K was accomplished in two ways: a linear relationship and a square relationship with the damage degree corresponding to the shear capacity dominated by the section area and the nominal diameter of the damaged stud. This coefficient was applied using Eurocode 4, AASHTO LRFD (2014) and GB50017-2003 (2003) and compared with the test results found in the literature. It was found that the proposed method produced good predictions of the shear capacity of stud shear connectors with initial damage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.955-963
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• 1999

In this paper, in other to analyze the performance of efficient key distribution protocol, we evaluate the key distribution processing method of push model like the Kerberos and pull model such as X.9.17 used in wired network. Also, we evaluate the procedure of key distribution protocol in satellite network. Besides, we analyze the performance of key distribution protocol procedure in view of delay and throughput in the case that key distribution protocol is processed based on Inband/Outband channel.

• Annual Conference of KIPS
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• 2003.05a
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• pp.153-156
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• 2003

기존 푸시 기술의 제품들이 가지는 상호 운용성을 해결하기 위한 CORBA 기반의 푸시 에이전트 모델(CPAM: CORBA-based Push Agen Model)은 사용자 요구에 적합한 정보만을 수집한 후 이를 사용자에게 전송하여주는 에이전트 프레임웍(Framework)이다. 이러한 푸시 에이전트는 푸시 에이전트 서버가 제공하는 정보의 양과 종류, 그리고 이를 이용하는 동시 사용자 수가 증가함에 다라 서버 시스템의 과부하 및 네트워크 트래픽의 증가가 초래된다. 이를 위해 본 논문에서는 푸시 에이전트 모델에 캐싱 기법을 적용함으로써 자주 요청되어지는 동일한 데이터에 대한 서버 시스템의 과부하를 감소시키도록 한다. 또한 클라이언트 푸시 에이전트의 상태 정보와 주제 분류에 따른 검색 키워드를 포함하고 있는 사용자 프로파일을 통해 효율적인 캐쉬 메모리 접근을 제공하도록 한다.

• Steel and Composite Structures
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• v.51 no.5
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• pp.529-543
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• 2024

The bonding efficacy of steel I-section embedded in metakaolin-fly ash-based geopolymer concrete (MK-FA-GC) was investigated in this study. Push-out tests were conducted on nine column specimens to evaluate the influence of compressive strength of concrete, embedded length of steel I-section, thickness of concrete cover, and stirrup ratio on the bond performance. Failure patterns, load-slip relationships, bond strength, and distribution of bond stress among the specimens were analyzed. The characteristic bond strength of geopolymer concrete (GC) increased with higher compressive strength, longer embedded steel section length, thicker concrete cover, and larger stirrup ratio. Empirical formulas for bond strength at the loading end were derived based on experimental data and a bond-slip constructive model for steel-reinforced MK-FA-GC was proposed. The calculated bond-slip curves showed good agreement with experimental results. Furthermore, numerical simulations using ABAQUS software were performed on column specimens by incorporating the suggested bond-slip relationship into connector elements to simulate the interface behavior between MK-FA-GC and the steel section. The simulation results showed a good correlation with the experimental findings.