• 농촌계획
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• 제14권3호
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• pp.27-36
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• 2008

Rapid increase of aging population and progressed migration from rural areas to urban areas have caused deficit of bus routes in local cities. This increasing burden of operation deficit affects the movement strategy of the transportation vulnerable who are using buses. Along with dramatically increased aging in Korea, there is an urgent need to implement a new method which can guarantee mobility rights of public transportation especially for the elderly. This study focuses on the case of Demand Responsive Transit(DRT) system that has been operating in America, Europe, Japan, etc. Kimhae(Sangdong-myeon and Saengnim-myeon) is selected as a study area. This study investigated the possibility of adopting DRT system on the perspectives of the consumer and provider by the analysis of traffic condition such as the number of transportation vehicles, present bus service and regulation and conduct of questionnaire survey which includes present bus service and DRT system and so on. In conclusion, DRT system in Kimhae city will reduce transport cost, increase affordability through the betterment of service level and secure mobility rights for the transportation vulnerable.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2548-2567
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• 2015

Recently, there has been a clear trend towards the application of ad hoc networking technology in civil aviation communication systems, giving birth to a new research field, namely, aeronautical ad hoc networks (AANETs). An AANET is a special type of ad hoc wireless network with a significantly larger scale and distinct characteristics of its mobile nodes. Thus, there is an urgent need to develop a simulator to facilitate the research in these networks. In this paper, we present a network simulator, Aero-Sim, for AANETs. Aero-Sim, which is based on the freely distributed NS-2 simulator, enables detailed packet-level simulations of protocols at the MAC, link, network, transport, and application layers by composing simulations with existing modules and protocols in NS-2. Moreover, Aero-Sim supports three-dimensional network deployment. Through several case studies using realistic China domestic air traffic, we show that the proposed simulator can be used to simulate AANETs and can reproduce the real world with high fidelity.

• 복합신소재구조학회 논문집
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• 제6권2호
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• pp.97-104
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• 2015

Compared with a strong axial rigidity due to large intial tension, cable has a weak laterally flexural rigidity. A variety of dynamic loads such as traffic loads and wind loads etc. cause the cables to vibrate significantly and affect the mechanical properties and the performance of cables. Therefore, vibration reduction design is an urgent task to control the vibration of cable-supported bridges. Because a various kind of dampers have shown to reduce the amplitude and duration time of vibration of cable from measured date in field test, damper can be considered that it is effective device significantly to reduce the amplitude and duration time in vibration of cable. Vibration characteristics of cable can change according to manufacturing method and type of established form, and damper has been designed according to distribution of natural frequencies and vibration modes. In this study, numerical analysis is used to show the reduction effects of vibrations and present the design of damper for vibration reduction of cable.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.533-535
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• 2018

현대시대 생활의 필수품인 자동차의 발전에 비례해 사고율도 급증적으로 증가하는 21세기에 좀 더 사고를 줄이고자, 본 논문은 차량의운전자가 급박한 상황이나 손이 불편한 노약자, 장애우분들을 위하여 편리성을 도모하고자 집필하게 되었다. 자동차의 안전사고 및 다양한 신호를 운전자가 음성으로 스마트폰을 통해 전달하면 자동차후면 LED pannel을 통하여 음성신호를 영상신호로 처리함으로써, 긴급한 상황이나 현재 상태를 명확히 전달이 가능하게 하였으며, 또한 근거리 통신망을 이용 근거리 상업 지역의 광고판으로써의 광고효과와 현 교통상황을 표시할 수 있게 연구를 제안하고자 한다.

• 한국군사과학기술학회지
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• 제17권5호
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• pp.561-568
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• 2014

The Republic of Korea Army is using R-NAD of MIL-STD-188-220 as a Media Access Control protocol. Under urgent situations, almost all stations transmit data frames and then the network will reach a saturation state. Several articles have been devoted to the study of R-NAD performance. However, most of them focus on comparing the performance of some NADs using network simulation tools. We propose an analytical model to compute the throughput of R-NAD under the assumption of a network traffic saturation. Analytical results were verified by Monte Carlo methods. We have shown that the performance of a success probability and an average idle time remains almost unchanged as the total number of stations increases. We have also shown that Type 1/2/4 operation mode outperforms Type 3 operation mode in throughput. The results showed that the system with a squelch detection achieved a better performance than the one without it. The longer DATA time had a higher throughput.

• 선박안전
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• 통권32호
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• pp.57-71
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• 2012

Recently, the navigation risk is increasing significantly with growing of vessels' volume and propelling marine facilities, water bridges and port development etc. At this point of time, the Ministry of Land, Transport, and Maritime Affairs introduced the Maritime Safety Audit(MSA) in amendment of the Korea Marine Traffic Law. audit results were survey for the last two years. As a result, appropriate certificate appears 11% among audit report, is an urgent need for improved quality of audit reports. This study is aimed to propose about Audit Personnel Education & Training System. To these solve, this paper analyzed the tendency of Audit Personnel Training. And also the opinions of user and experts were investigated and analyzed using Questionnaire survey methods. As a result, this paper was suggested, the construction of Audit Personnel Training System and the curriculum and training contents for 5-days of basic course, 2-days of expert course, 3-days of Qualification Maintain course.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.246-248
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• 2017

자율주행자동차는 자동차 스스로 주변 환경을 인식하여 위험을 판단하고 주행경로를 계획하여 운전자 주행조작을 최소화하며 스스로 안전주행이 가능한 인간 친화형 자동차를 말한다. 자율주행자동차가 필요한 이유는 한정된 도로 상에서의 교통체증을 감소와 탄소 저감을 목적으로 시작되었다. 이러한 관련 자율주행자동차 사업 추진은 자동차 업체의 기존 사업 유지 및 확대와 ICT 기업의 신규사업 창출과 진입효과를 기대 할 수 있다. 관련 인증기관은 자율주행자동차에 대한 법적과 제도적 기반 마련이 시급하다. 그럼으로써 소비자에게 새로운 서비스가 제공될 수 있을 것이다. 따라서 본 논문에서는 자율주행자동차에 대한 기술개발 동향을 소개한다.

• Journal of Communications and Networks
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• 제13권2호
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• pp.132-141
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• 2011

IEEE 802.15.4 networks are a feasible platform candidate for connecting all health-care-related equipment dispersed across a hospital room to collect critical time-sensitive data about patient health state, such as the heart rate and blood pressure. To meet the quality of service requirements of health-care systems, this paper proposes a multi-priority queue system that differentiates between various types of frames. The effect of the proposed system on the average delay and throughput is explored herein. By employing different contention window parameters, as in IEEE 802.11e, this multi-queue system prioritizes frames on the basis of priority classes. Performance under both saturated and unsaturated traffic conditions was evaluated using a novel analytical model that comprehensively integrates two legacy models for 802.15.4 and 802.11e. To improve the accuracy, our model also accommodates the transmission retries and deferment algorithms that significantly affect the performance of IEEE 802.15.4. The multi-queue scheme is predicted to separate the average delay and throughput of two different classes by up to 48.4% and 46%, respectively, without wasting bandwidth. These outcomes imply that the multi-queue system should be employed in health-care systems for prompt allocation of synchronous channels and faster delivery of urgent information. The simulation results validate these model's predictions with a maximum deviation of 7.6%.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.269-272
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• 2004

After concrete casts, temperature decent and shrinkage bring volume changes of concrete pavement. Microcracking and cracking in concrete pavement are caused by these volume changes. As a result, durability of concrete pavement is deteriorated. Recently, Very-Early Strength Latex Modified concrete(below:VESLMC) from the beginning of High-Way is used as urgent repair material for bridge deck. The advantage of VESLMC is that compressive and flexural strength at 3 hours age are 4.5MPa and 21MPa respectively. It allows the traffic to open in 3 hours. But, this material has the problem which is early-age shrinkage cracking caused by water self-dissipation with rapid hydration reaction and water evaporation with body dry. Unfortunately, until now, the research about early-age shrinkage of VESLMC leaves something to be desired. Therefore, the purpose of this study is to present the early-age shrinkage of VESLMC respect to latex contents and shrinkage ratio to maximum length change that can help field engineers' skill. Latex contents of 0, 5, 10, 15, $20\%$ in standard of same workability in VESLMC are selected by experimental variables. After initial set, shrinkage value was measured with 10mm LVDT for 3 days. The results of maximum shrinkage ratio were 0.019, 0.017, 0.023, $0.027\%$ respectively.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.416-419
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• 2004

최근에는 컴퓨터 시뮬레이션을 통해서 실제 전투 자산을 가동하지 않고 실전과 같은 전투경험을 부여하고 있다. 이러한 시뮬레이션이 실제와 똑같은 환경을 구축하기 위해서는 현재 사용하는 워게임 모델을 운용하기 위한 데이터베이스가 잘 구축되어야 하고, 그 데이터베이스를 포함한 페더레이트(federate)간의 연동(federation)이 네트워크 상에서 잘 수행되어야 한다. 이에 본 논문에서는 전장 데이터(이하 액티브 패킷)의 신속한 전달을 필요로 하는 긴급한 실제상황과 유사한 전장공간을 구축할 수 있도록 액티브 네트워크 상에서 페더레이트(혹은 액티브 노드) 간의 효율적인 트래픽 처리가 가능한 가상 전장 환경을 구성하고, 이에 대한 유효성을 모의 실험을 통하여 검증하였다.