• 산업기술연구
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• 제28권B호
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• pp.245-250
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• 2008

Recently, mobile devices have supported wireless LAN as well as bluetooth, where the services such as heterogeneous network access and seamless mobility connection are important. Even though the mobility and physical network might be varied, an efficient communication mechanism for the network access and a robust mobility management of mobile devices are needed. In this paper, we design and implement a Bluetooth system with mobile LAN access capability. The proposed system has the following features; 1) IP connection is enabled by BENP in the link layer, 2) The networks devices of heterogeneous mobile devices are integrated into a single virtual network interface, 3) IP mobility between the bluetooth and wireless LAN is supported by mobile IP. The experimented results show that the packet loss and delay time during the handover duration is reduced by predicting the handover among different networks followed by the setup of any required parameters in advance.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.606-611
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• 2009

MiStrut is a new method to establish structural stability in designing braced excavations by making a rigid connection between top-level steel beams and soldier beams. MiStrut has a function of working as a strut as well as supporting cover plates of top-level steel beams. The structural mechanism of MiStrut is supposed to reduce flexural deformation of soldier beams, which may lead to reduced lateral earth pressures behind excavation. In this research, for verification of the performance of MiStrut, shear-wave velocities of subsurface soil before and after excavation was compared. The rigid connection of main girder beams with soldir beams reduced shear-wave velocity by 67% and lateral earth pressures by 90%, which indicates that MiStrut is effective development in reducing lateral earth pressures on braced excavation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.239-242
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• 2005

The purpose of this research was focused on substantiating an effects of tendon-layouts and compressed stress($=f_{pc}$) induced by post-tensioning on seismic performance of post-tensioned flat plate slab-column connection designed as non-participating system. To accomplish this purpose, an experimental research of flat plate exterior slab-column connections subjected to gravity load and reversed lateral displacement history are presented. As a result, tendon-layout is a main variable to influence failure mechanism, dissipated energy and lateral deformation capacity. Furthermore, compressed stress ($=f_{pc}$) induced by post-tensioning enhanced the seismic performance of flat plate slab.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.413-420
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• 2002

Recent experimental research results of connection method between steel pipe pile and concrete footing are provided based on various experimental observations. It gives a shedding light toward developing better and concrete connection method for steel pipe pile at the field application. In this study, the newly developed method is tested for compressive, pull put and combination load including moment with carefully designed monitoring system. The measured data show that new method have at least equivalent or better load resistant capacities compared with those of specified method in Korea Highway Corporation design code. It is also tried to define and investigate the load transfer mechanism for new method.

• 한국정보통신학회논문지
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• 제2권3호
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• pp.325-333
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• 1998

본 논문에서는 BSA(Basic Service Area)에 독립적으로 분산되어 있는 이동단말기들을 대상으로 기존 STM(Synchronous Transfer Mode)에서의 유휴채널을 이용하여 다른 트래픽을 지원하므로 서 이용률을 극대화시킬 수 있는 통계적 다중화 기능을 무선매체를 통해 확장하는 기능을 수행하는 무선 ATM 망에서의 매체접근제어 프로토콜과 멀티미디어 서비스특성에 따른 기존 유선망 기반에서의 고정할당방식(연결 지향적) 및 랜덤할당방식(비연결지향적)을 개선하기 위한 동적 예약 기반의 매체접근제어 프로토콜에 대해 제시한다.

• 정보통신설비학회논문지
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• 제9권2호
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• pp.42-47
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• 2010

차세대 무선 네트워크 환경에서는 다양한 이기종 무선 엑세스 기술들이 존재하여 서비스 되고 다양한 서비스를 하나의 단말로 지원하는 멀티 인터페이스 시스템의 출현이 예상되고 있다. 이러한 멀티 인터페이스 특성상 많은 연구들이 주로 전력제어 측면에서만 이루어지고 있다. 그러나 통합 우선네트워크 안에서 다양한 서비스가 원활하게 운용되기 위해서는 QoS를 고려한 이기종망간 네트워크접속에 대해서 연구가 필요하다. 본 논문에서는 전력제어 측면 외에 QoS를 고려한 사전인증 및 네트워크 접속 메커니즘을 제안한다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.76-79
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• 2009

최근 학회와 산업분야에서 모바일 사용자들에게 다양한 무선 기술들을 통합하여 끊김없는 접속을 제공하기 위한 노력들이 이루어지고 있다. 단말의 연속적인 서비스 지원을 위해서는 고속의 핸드오버 기능 및 위치관리 기능이 필요하다. 특히 고속의 핸드오버를 수행하기 위해서는 액세스망에 의존적인 데이터링크 계층 기능들과 IP기반 이동성 기능들이 밀접히 연계되어 동작되어야 한다. 본 논문에서는 대표적인 핸드오버 기술인 MIH(Media Independent Handover)의 이론적 배경과 제안한 핸드오버 결정 기술과 함께 비교 분석한다.

• Steel and Composite Structures
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• 제47권2호
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• pp.203-216
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• 2023

The composite beam connections often encountered fracture failure in the welded bottom flange joint, and a bottom flange bolted connection has been proposed to increase the deformation ability of the bottom flange joint. The seismic performance of the bottom flange bolted composite beam connection was suffered from both the composite action of concrete slab and the asymmetric load transfer mechanisms between top and bottom beam flange joints. Thus, this paper presents a comprehensive numerical study on the working mechanism of the bottom flange bolted composite beam connections. Three available modelling methods and a new modelling method on the flange-stud-slab interactions were compared. The efficient numerical modeling method was selected and then applied to the parametric study. The influence of the composite slab, the bottom flange bolts, the shear composite ratio and the web hole shape on the seismic performance of the bottom flange bolted composite beam connections were investigated. A hogging strength calculation method was then proposed based on numerical results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권6호
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• pp.2811-2830
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• 2017

In this paper, we study the problem of mobile data offloading for a network that contains multiple mobile network operators (MNOs), multiple WiFi or femtocell access points (APs) and multiple mobile users (MUs). MNOs offload their subscribed MUs' data traffic by leasing the unused Internet connection bandwidth of third party APs. We propose a combinatorial auction-based two-stage matching mechanism comprised of MU-AP matching and AP-MNO matching. The MU-AP matching is designed to match the MUs to APs in order to maximize the total offloading data traffic and achieve better MU satisfaction. Conversely, for AP-MNO matching, MNOs compete for APs' service using the Nash bargaining solution (NBS) and the Vickrey auction theories and, in turn, APs will receive monetary compensation. We demonstrated that the proposed mechanism converges to a distributed stable matching result. Numerical results demonstrate that the proposed algorithm well capture the tradeoff among the total data traffic, social welfare and the QoS of MUs compared to other schemes. Moreover, the proposed mechanism can considerably offload the total data traffic and improve the network social welfare with less computation complexity and communication overhead.

• 인터넷정보학회논문지
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• 제6권1호
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• pp.1-12
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• 2005

최근 인터넷을 통한 사이버 총격의 형태가 다양해지고 복잡해지면서 네트워크 침입자를 효과적으로 탐지하고 신속하게 대응하는 것이 어려워지고 있다. 특히, UDP 계열의 DoS, DDoS 공격에서 IP 패킷 내의 근원지 주소를 다른 호스트의 IP로 위조하여 공격하거나, TCP 기반의 우회 연결 공격 등의 경우에서 침입자의 실제 위치를 추적하고 고립화시키는 것은 어려운 일이다. 본 논문에서는 TCP 연결 공격과 같은 사이버 공격에 신속히 대응하기 위해 액티브 네트워크에 기반 한 보안 구조를 제안한다. 액티브 네트워크를 이용하여 보안 관리 프레임워크를 설계하고, TCP 기반 네트워크 침입자를 추적하고 고립화하기 위한 보안 메커니즘을 구현한다. 구현된 보안 메커니즘이 공격 시나리오에 따라 동작하는 과정을 실험 환경에서 시험하며, 실험 결과를 분석한다.