• Journal of Korean Society of Transportation
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• v.35 no.2
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• pp.91-104
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• 2017

In this study, we discuss the modeling of domestic transport sector using GCAM(Global Change Assessment Model). The GCAM is one of integrated assessment models widely used in internationally modeling community, and applied for the evaluation of IPCC 5th Report. Nevertheless, it is noted that there are a considerable number of problems in its application to domestic transport sector. First, the base year information of GCAM for detailed transportation service demand is found not consistent with national statistics. Second, the transportation sector simulation results do not properly reflect the past trends of service demand. Thus, the base year service demand is carefully matched with the detailed national statistics. In addition, the existing models were checked and modified so that the simulation results of service demand can accurately reflect past trends of national statistics. As a result, it is reported in detail how the current GCAM simulation results are corrected and how the trend of past transportation sector service demands is properly reflected. This study is expected to be useful as a basic tool for future scenario analysis for transportation policy, technology evaluation and greenhouse gas reduction measures.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.153-161
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• 2015

We propose a privacy-preserving location-based service (LBS) which supports top-k search service. The previous schemes hurt the privacy of either the user and the location of the objects because they are sent to the LBS server in a plaintext form. In the proposed method, by encrypting them with the fully-homomorphic encryption, we achieved the top-k search is possible while the information on them is not given to the LBS server. We performed a simulation on the proposed scheme with 16 locations where k is 3. The required time is 270 hours in a conventional desktop machine, which seems infeasible to be used in practice. However, as the progress of the hardware, the performance will be improved.

• The KIPS Transactions:PartC
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• v.8C no.1
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• pp.41-50
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• 2001

With growth of Internet, real time multimedia application services require guarantee of QoS (Quality of Service). However, the existing Internet based on best-effort service is not enough to support those services, so MARS model to support IP multicast over ATM networks and RSVP to provide heterogeneous QoS by resource reservation scheme are proposed. As a simulation result, it is proved that processing delay of MARS is increased and success of resource reservation is decreased as a number of QoS change request of a receiver is increased. Therefore, it is important to provide heterogeneous QoS that distribute a load of MARS caused by convergence of messages and efficiently manage the resource of network as to find out scale of receivers and frequency of QoS change request.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.86-93
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• 2015

Recently, the development of Maritime Service Portfolios (MSPs) for the safe navigation of ship has been discussed internationally. For the successful service of the MSPs, first of all, studies for the standardization about the structure and data structure of MSPs should be preceded. Also, it is necessary to evaluate and assess whether the services are effective for safe navigation, and provided data and portrayal methods are proper. However, because great dangers will be accompanied when untested MSPs about their effectiveness and safety are applied in real ship navigation, it is necessary that effectiveness and safety of the MSPs should be proven under various navigational conditions and environments by simulation. In this paper, we propose a 3D navigation simulation system using desktop PC environment, which is proper for evaluating the effectiveness of MSPs. The system consists of three modules which are simulation scenario editor, 3D visualization of navigational environment and 2D navigational equipment. The scenario editor module provides an environment setting for simulation, such as properties, routes and positions of vessels and aids to navigations. It also provides functions to create a scenario for the simulation to operate. Additionally, the 3D visualization module provides 3D navigational environment which shows interplay between geographical and navigational environment based on the created scenario. The 2D navigational equipment module provides visualization functions of various navigational equipment, shows the interaction between ship's navigational equipment and ship's environment. The simulation scenario, in which various kinds of ships are routing in the port, is created by the developed simulation system, and experimented whether this developed system is appropriate to evaluate and assess the MSPs developed by the International Maritime Organization.

• Journal of the Korea Society for Simulation
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• v.22 no.3
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• pp.43-53
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• 2013

The paper addresses the introduction of outsourcing of delivery service for the small service industries such as delivery based restaurant in order to increase the profit and revenue of the service company, upgrade the delivery satisfaction for the customers, and expand the welfare of the senior people through the work. The chinese restaurants are selected as model service companies, outsourcing of delivery services are suggested for those restaurants and simulation models are developed for all operation systems for them. Some of input data for the simulation are collected from the real world and others are refined through the interview with the field workers. 6 scenarios are established considering the number of deliverers and delivery charges and simulation experiments for each scenario have been done according to the 3 kind of situations of the service companies. The results show that introduction of outsourcing increases the revenue and profit of the service company, decreases the service time for the customers and increases the revenue of the delivery outsourcing company employing the senior people. So delivery outsourcing for the service industries can be considered as a good solution for the welfare problem of the senior people.

• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.19-28
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• 2011

The safety applications based on the IEEE 802.11p, periodically transmit the safety-related information to all surrounding vehicles with high reliability and a strict timeline. However, due to the high vehicle mobility, dynamic network topology and limited network resource, the fixed beacon scheduling scheme excess delay and packet loss due to the channel contention and network congestion. With this motivation, we propose a novel beacon scheduling algorithm referred to as spatial-aware(SA) beacon scheduling based on the spatial context information, dynamically rescheduling the beaconing rate like a TDMA channel access scheme. The proposed SA beacon scheduling algorithm was evaluated using different highway traffic scenarios with both a realistic channel model and 802.11p model in our simulation. The simulation results showed that the performance of our proposed algorithm was better than the fixed scheduling in terms of throughput, channel access delay, and channel load. Also, our proposed algorithm is satisfy the requirements of vehicular safety application.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.306-307
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• 2022

Recently, in the process of developing, verifying, and upgrading the e-Navigation service and autonomous navigation system, there is an increasing demand for inter-working with a ship-handling simulator that can simulate actual maritime traffic conditions. In this paper, to develop a ship-handling simulation system based on actual maritime traffic conditions, a simulation server was built, received information on the actual maritime traffic conditions from the e-Navigation linkage system, and changed to information for operating the ship-handling simulator. In order to provide simulation images to users, 3D shape modeling for trade ports, coastal ports in Korea and major type of ship were performed. The developed system will be used for the advancement of e-Navigation service, development and verification of autonomous navigation systems, by enabling simultaneous processing of more than 10,000 ships and allowing users to simulate actual maritime traffic conditions in the desired area.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.1334-1337
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• 2011

HLA(High Level Architecture)는 분산 환경의 모델링 및 시뮬레이션(Modeling & Simulation)을 위한 공통 아키텍처를 제공하는 기술 표준이며, RTI(Run-Time Infrastructure)를 통해 HLA 서비스를 제공한다. HLA는 연동 객체 모델인 FOM(Federation Object Model)을 기반으로 시뮬레이션 환경을 구성하며, 시뮬레이션에 참여하는 모든 시뮬레이터는 동일한 FOM을 소유해야 한다. 따라서 시뮬레이션 체계 간 연동을 수행하기 위해서는 FOM을 통합하거나 FOM 간 연동을 위한 게이트웨이를 구현해야 한다. 한편, FOM을 통합하는 방법은 각 시뮬레이션의 연동 인터페이스 수정이 필요하기 때문에 게이트웨이를 구현하는 방법이 기존 시스템의 변경을 최소화할 수 있다. 따라서 본 논문은 HLA기반 시뮬레이션의 체계 간 연동을 제공할 수 있는 게이트웨이 구조를 제시한다. 특히, XML 형태의 객체 모델을 기반으로 교환 메시지를 정의하고, 메시지 처리 모듈을 게이트웨이에 플러그인 함으로써 시뮬레이션 체계 간 연동의 용이함을 보여준다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.367-369
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• 2004

인터넷 사용자들의 증가로 인해 신뢰성 있는 차별화된 고품질의 서비스를 제공하기 위해서는, 사용자와 서비스 제공자 간의 SLA(Service Level Agreement)를 고려한 웹 서버 클러스터의 부하 분산 기능은 필수적이다. 본 논문에서는 이질 웹 서비스 환경에서 SLA 를 만족시켜주는 동적 부하분산 기법을 연구하였으며, 시뮬레이션 결과를 통해 기존의 정적 기법 보다 웹 서버의 응답시간(Response Time)성능이 개선되는 것을 확인하였다.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.179-183
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• 2002

본 논문에서는 광대역 CDMA망에서 음성, 비디오, 데이터와 같은 멀티미디어 서비스를 제공하기 위해서 다양한 서비스 특성에 적합한 액세스 제어 방법을 제안한다. 즉 서비스별로 다른 Eb/No 값을 이용함으로써 서비스의 BER을 조절하고 음성과 비디오의 전송률이 시간에 따라 변하는 특성을 이용하여 데이터의 전송률을 제어하는 방법을 제안하였다. 또한 각 방법에 대한 시뮬레이션과 분석을 수행하였다. 성능 분석결과 제안된 액세스 방법을 사용할 경우 데이터에 대한 지연을 통해 전체적인 outage 발생확률을 감소시킴을 알 수 있었다.