• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.902-909
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• 2023

This study evaluated the performance test of a small-sized LTE-Maritime(LTE-M) transceiver that was developed and promoted to expand the use of intelligent maritime traf ic information services led by the Ministry of Oceans and Fisheries with the aim of supporting the prevention of maritime accidents. Accoriding to statistics, approximately 30% of all marine accidents in Korean water occur with ships weighing less than 3 tons. Therefore, the blind spots of maritime safety must be supplemented through the development of small-sized transceivers. The small transceiver may be used in fishing boats that are active near coastal waters and in water leisure equipment near the coastline. Therefore, verifying whether sufficient performance and stable communication quality are provided is necessary, considering the environment of their real usage. In this study, we reviewed the communication quality goals of the LTE-M network and the performance requirements of small-sized transceivers suggested by the Ministry of Oceans and Fisheries, and proposed a test plan to appropriately evaluate the performance of small-sized transceivers. The validity of the proposed test method was verified for six real-sea areas with a high frequency of marine accidents. Consequently, the downlink and uplink transmission speeds of the small-sized LTE-M transceiver showed performances of 9 Mbps or more and 3 Mbps or more, respectively. In addition, using the coverage analysis system, coverage of more than 95% and 100% were confirmed in the intensive management zone (0-30 km) and interesting zone (30-50 km), respectively. The performance evaluation method and test results proposed in this paper are expected to be used as reference materials for verifying the performance of transceivers, contributing to the spread of government-promoted e-navigation services and small-sized transceivers.

• Journal of Internet Computing and Services
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• v.20 no.3
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• pp.119-128
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• 2019

This study aims to analyze the research trends on Smart City and to present implications to policy maker, industry professional, and researcher. Cities around globe have undergone the rapid progress in urbanization and the consequent dramatic increase in urban dwellings over the past few decades, and faced many urban problems in such areas as transportation, environment and housing. Cities around the globe are in a hurry to introduce Smart City to pursue a common goal of solving these urban problems and improving the quality of their lives. However, various conceptual approaches to smart city are causing uncertainty in setting policy goals and establishing direction for implementation. The study collected 11,527 papers titled "Smart City(cities)" from the Scopus DB and Springer DB, and then analyze research status, topic, trends based on abstracts and publication date(year) information using the LDA based Topic Modeling approaches. Research topics are classified into three categories(Services, Technologies, and User Perspective) and eight regarding topics. Out of eight topics, citizen-driven innovation is the most frequently referred. Additional topic network analysis reveals that data and privacy/security are the most prevailing topics affecting others. This study is expected to helps understand the trends of Smart City researches and predict the future researches.

• Journal of the Korea Convergence Society
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• v.11 no.9
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• pp.1-6
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• 2020

In this study, we propose an association inference model based on data bias optimization for road hazard detection. This is a mining model based on association analysis to collect user's personal characteristics and surrounding environment data and provide traffic accident prevention services. This creates transaction data composed of various context variables. Based on the generated information, a meaningful correlation of variables in each transaction is derived through correlation pattern analysis. Considering the bias of classified categorical data, pruning is performed with optimized support and reliability values. Based on the extracted high-level association rules, a risk detection model for personal characteristics and driving road conditions is provided to users. This enables traffic services that overcome the data bias problem and prevent potential road accidents by considering the association between data. In the performance evaluation, the proposed method is excellently evaluated as 0.778 in accuracy and 0.743 in the Kappa coefficient.

• The Journal of Bigdata
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• v.6 no.2
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• pp.139-149
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• 2021

Ddareungi, a public bicycle service in Seoul, establishes itself as a means of daily transportation for citizens in Seoul. We speculated that the pattern of using Ddareungi may have changed since COVID-19. This study explores changes in using Ddareungi after COVID-19 with descriptive statistical analysis and network analysis. The analysis results are summarized as follows. The average traveling distance and average traveling speed have decreased over the entire time in a day since COVID-19. The round trip rate has increased at dawn and morning and has decreased in the evening and night. The average weighted degree and average clustering coefficient have decreased, and the modularity has increased. The clusters, located north of the Han River in Seoul, had a similar geographic distribution before and after COVID-19. However, the clusters, located south of the Han River, had different geographic distributions after COVID-19. Traveling routes added to the top 5 traffic rankings after COVID-19 had an average traveling distance of fewer than 1,000 meters. We expect that the results of this study will help improve the public bicycle service in Seoul.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.717-722
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• 2012

Disaster management system can prepare enough for a social disaster. In addition, it is measures to reduce damage. When, where and how to prepare for a disaster will happen we can not expect an appropriate sense of crisis, disaster response and is the right choice early. In this paper, the next national disaster safety sector effective use SNS will find ways. To do this successfully in the field of international disaster safety use cases and measures are derived that can be applied to our country. As a result, comprehensive and systematic introduction of disaster management system to minimize the damage will contribute effectively to the rapid disaster recovery.

• Journal of Digital Convergence
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• v.11 no.6
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• pp.187-192
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• 2013

Current Korean ITS policies are decided by two persuading parties, so that ITS industry has great difficulties in establishing unified policies and developing ITS related industries. This paper provides the analysis of current Korean ITS policy issues, and suggests the ways how to activate the ITS industry. First, the ITS policy should be unified through agreement between related departments in government. Second, ITS should be recognized as social overhead capital and thus implemented as national infrastructure. Third, define the range of ITS services to prevent confusion with general wireless and mobile communication services.

• Information Systems Review
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• v.7 no.1
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• pp.65-80
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• 2005

The Seoul Metropolitan Subway Corporation (SMS) and the Seoul Metropolitan Rapid Transit Corporation (SMRT), which manage the city's eight subway lines, are intending to overcome their operational inefficiencies. The two investigators of the paper realize with emphasis that it is essential for the two subway authorities to analyze subway transit data prior to put policies and plans into practice. In this paper, the investigators propose a new, and an intuitive, way of analyzing subway passenger transit patterns. To achieve this goal, they have implemented a data mart by blending the "Pass Card" log data into the multidimensional model. The subway passenger's transit patterns and the practical implications of this system are also investigated.

• KDI Journal of Economic Policy
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• v.10 no.4
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• pp.61-81
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• 1988

우리나라 택시산업(産業)에 대한 정부규제(政府規制)는 크게 보아 요금규제(料金規制), 면허규제(免許規制) 그리고 서비스관련규제(關聯規制)로 나눌 수 있다. 정부규제에 의한 문제점으로서는 요금규제(料金規制)에 의한 초과수요(超過需要)의 존재와 제한적인 면허발급제도(免許發給制度)에 의해 발생한 면허에 대한 프리미엄과 이의 배분을 둘러싼 여러가지 비효율(非效率)과 형평(衡平)의 문제(問題)라고 할 수 있다. 우리나라 택시산업(産業)은 비호출방식(非呼出方式)의 노상유객(路上誘客)을 주로 하는 소위 순항식(巡航式)(cruising)시장(市場)이기 때문에 자유경쟁(自由競爭)의 상태에서는 시장정보전달(市場情報傳達)의 불완전성(不完全性)으로 인한 시장실패(市場失敗)의 가능성(可能性)이 존재한다고 할 수 있다. 따라서 이것을 보정(補正)하기 위한 가격규제(價格規制)의 필요성(必要性)은 인정할 수 있으나, 정부에 의한 제한적인 사업면허(事業免許)의 발급(發給)과, 임의적인 증차결정(增車決定) 및 배분방식(配分方式)은 그 정당성(正當性)이 의문시된다고 할 수 있다. 따라서 장기적(長期的)으로 택시에 대한 면허제(免許制)는 폐지되어야 할 것이다. 그러나 택시증차(增車)의 문제는 도시교통혼잡의 문제와 관련이 있으므로, 중(中) 단기적(短期的)으로는 현행의 직접규제방식(直接規制方式)을 개선하여 일정한 자격을 갖춘 출원자(出願者)에게는 일정금액의 공탁금(供託金)만 납부하면 의무적으로 면허를 내어주는 간접규제방식(間接規制方式)으로의 전환을 고려해야 할 것이다. 또한, 태당(台當) 1일(日) 승객회전률(乘客回轉率)의 증가를 통한 승차난완화(乘車難緩和)를 위해 현행(現行) 요금체계(料金體系)를 개선해야 할 것이다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.104-106
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• 2015

최근 인간의 개입을 최소화하면서 임무를 수행할 수 있는 무인항공기에 대한 활용도가 높아지는 가운데 무인선(Uamanned Maritime Vessel) 운용에 대한 관심도 높아지고 있다. 국내에서 무인선(Uamanned Maritime Vessel) 관련 프로젝트는 오염 방제 지원, 불법조업 감시, 조난자 수색 구조 등의 감시 및 구난 방제 지원 임무와 수로조사, 해양 기상 모니터링, 적조 감시 등 해양 조사 등을 목적으로 무인선(Uamanned Maritime Vessel)을 개발하는 중이다. 무인선은 관제센터(Maritime Control Station) 또는 모선을 통하여 원격 통제로 임무를 수행하게 되며, 이를 위하여 다양한 정보가 무선통신을 통하여 유인선-무인선, 무인선-무인선, 무인선-관제센터 간에 실시간으로 제공될 것으로 예상되어진다. 본 연구에서는 ITU-R Study Group Woking Party 5B를 분석한 후, 국내 개발 예정인 무인선(Uamanned Maritime Vessel) 운용을 위하여 요구되는 통신 서비스를 구분하여 정의 및 분류하고, 이를 바탕으로 데이터 전송속도, 트래픽 이용시간, 교통량을 바탕으로 필요한 주파수 산정을 위한 기초자료를 제공하는데 목적이 있다.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.355-356
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• 2007

21세기는 한국 철도의 르네상스시대라고 부르고 있다. 이는 자동차와 비행기 등 다른 교통수단에 의해 낙후되어있던 철도가 다시 안전하면서도 정확한 운송시간 등으로 그 경쟁력을 확보해가고 있으며 때를 같이하여 고속철도의 개통을 앞두고 있기 때문이다. 이러한 철도의 경쟁력을 강화하는데 크게 기여한 부분 중 하나가 신호 보안장치 즉 열차제어장치의 발전에 있다고 하겠다. 하지만 열차를 제어하기 위해선 실시간격으로 열차의 절대 위치를 알아야만 하는 문제점이 있다. 이를 비교적 쉽게 극복할 수 있는 방법 중 하나가 인공위성을 이용한 통신기술을 이용하는 것이다. 이는 이미 다른 분야에서는 상용화되어 서비스가 이루어지고 있는 GPS(Global Positioning System)이다. 본 논문에서는 열차의 절대 위치를 GPS(Global position system)를 이용하여 구해 보고자 한다. 이를 위해 GPS 신호 추적을 확장형 칼만 필터를 적용하여 열차의 속도 변화에 대한 GPS 신호 추적 루프를 예측 제어함으로써 보다 정확하고 빠른 GPS 위치 정보를 도출하였다.