• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1187-1191
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• 2008

우리나라는 기상이변에 따른 게릴라성 집중호우의 빈도 및 강우량이 해가 거듭할수록 증가함에 따라 이로 인한 피해지역의 범위 및 피해액이 계속 증가하고 있는 실정이다. 이에 국가 및 각 연구기관들은 전국의 자연유역 및 도시유역에 대해 홍수범람의 예상지역 및 대피지도 작성 등을 통해 재해에 대한 사전 피해예방및 보험제도 등으로 그 피해를 경감하고자 각종 사업 및 연구를 활발히 진행하고 있다. 이러한 연구에 주로 이용되는 것이 지리정보시스템(GIS)으로서, 기존 수작업 과정 등을 통해 소요되는 많은 시간과 비용적 투자를 획기적으로 줄이면서도 보다 정밀도 있는 홍수범람지도를 작성하는데 크게 이바지 하고 있다. 하지만 강력하고 광범위적인 기능의 GIS 프로그램에 대한 이해 및 원시자료의 부족과 이 자료들을 이용한 실제 지형 구축 및 편집 등의 어려움으로 GIS를 이용한 홍수범람해석은 여전히 실무에서 널리 적용되지 못하고 있는 실정이다. 따라서, 본 연구에서는 실무적 적용성 및 범용성을 고려하여 자연유역이 대부분 포함되는 지방2급 고부천 유역을 대상으로 최근 토목 전반의 평면적 2D설계 개념에서 입체적 3D설계로 변화하는데 중요한 역할을 하고 있는 Autodesk사의 Civil 3D를 이용하여 수치지형도 및 측량데이터 등 다양한 원시자료로부터 실제 지형과 매우 유사한 3D 지형을 구축하고, Civil 3D의 3rd Party 프로그램인 Engineered Efficiency사의 EE HEC-RAS Tool을 이용하여 하천정비 기본계획 및 소하천정비 종합계획 등 실무에서 홍수위 계산에 가장 많이 이용되는 1차원 수치모형인 HEC-RAS와 전 후처리를 연계함으로서 빈도별 홍수위에 따른 홍수범람 수심 및 범람지역 등을 산정하였다. 본 연구는 실무 설계에서 가장 많이 이용하는 Autodesk 프로그램의 적용을 통해 기존 GIS개념 및 프로그램의 이해부족과 편집의 어려움을 해소하여 실무적 홍수범람해석에 시간적, 비용적 효율성을 높이고 기존 수작업의 오류를 보완함으로서 보다 정밀한 홍수범람해석 및 치수경제성 분석에 도움이 될 것으로 판단된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.627-630
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• 2009

Ejector system can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an configuration and operating conditions for an ejector in the condition of sonic and subsonic. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Numerical simulation was adopted for an optimal geometry design and satisfying the required performance. Also, some ejectors with a various of nozzle throat and mixing chamber diameter were manufactured precisely and tested for the comparison with the calculation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1573-1581
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• 2006

To utilize actively the agent which is one of the elements of revitalization of Agro-Foods Mobile I-commerce, an essential prerequisite is agent security. IF using partial PKI(Public Key Infrastructure)-based confirmation mechanism providing security for the agent, the size of agent is becoming larger, the result of the transmission speed is slow, and the confirmation speed is tardy as well because of performing calculation of public keys such as RSA and needing linkage with the CA for the valid examination of certificates. This paper suggests a mechanism that can cross certification and data encryption of each host in the side of improving the problems of key distribution on agent by shaping key chain relationship. This mechanism can guarantee the problem of ky distribution by using agent cipher key(ACK) module and generating random number to fit mobile surroundings and to keep the secret of the agent. Suggested mechanism is a thing that takes into consideration security and efficiency to secure agent for the revitalization of M-Commerce, and is a code skill to make the agent solid and is a safe mechanism minimizing the problems of memory overflow.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.1
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• pp.38-49
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• 2017

In general, railroad operation companies sell tickets to maximize their profits by applying the ticketing release time (when selling any tickets regardless of trip distances). This study is to analyze the effect of the release time on KTX ticket reservation behavior. The reservation behavior in this study means the reservation time calculated by difference between ticketing time and departure time. The data come from KTX ticket sales data of Gyeongbu-line for a week including Saturday and Sunday. The results show that the factors to affect the reservation time are day of the week, trip distance and operation direction, in addition to the release time. Furthermore, most of tickets were reserved three hours before their departure time, and most of the up line weekend users reserved their tickets a day before the departure time. Before the release time, reservation time was affected by up line and long distance travel. On the other hand, after the release time, it was affected by long distance travel and Sunday.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.11-17
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• 2017

Organizations are experiencing an ever-growing concern of how to prevent confidential information leakage from internal employees. Those who have authorized access to organizational data are placed in a position of power that could well be abused and could cause significant damage to an organization. In this paper, we investigate the task of detecting such insider through a method of modeling a user's normal behavior in order to detect anomalies in that behavior which may be indicative of an data leakage. We make use of Hidden Markov Models to learn what constitutes normal behavior, and then use them to detect significant deviations from that behavior. Experiments have been made to determine the optimal HMM parameters and our result shows detection capability of 20% false positive and 80% detection rate.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1057-1063
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• 2014

Concerning $CO_2$ reduction from International Societies, lots of laboratories and relevant societies suggest many reports on how to reduce fuel consumption from their specific ways. Undoubtedly, cutting costs is the final desired destination for owner outcome, but many questions there are on the way yet: how is this measure working? how efficient is it? On what size of ship would it work best and be the most effective? etc. Fuel cost is one of the major cost elements for ship owners and/or operators. And by reducing fuel consumption owners and/or operators will reduce both their costs and the environmental impact from their ship. This paper is aim to address how the measures work for saving fuel consumption through improve propulsion efficiency, installation cost and benefit can be calculated easily in the return on investment for estimated one year operation, and finally their compatibility with other fuel saving measure devices.

• The Journal of Korean Association of Computer Education
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• v.17 no.1
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• pp.35-50
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• 2014

The current curriculums for the gifted and talented students in informatics are not practical and systematic in teaching methods because it is hard to provide the gifted and talented students with appropriate education individualized at their own levels. Furthermore, there are still some problems in previous curriculums for the gifted and talented students in informatics as follows. First, there are not sufficient on previous curriculums for the gifted and talented education in informatics in middle and high schools. Second, previous curriculums in use do not contribute to cultivating the creativity, problem-solving, logical thinking abilities and insight for the gifted students. Third, there is no curriculum, which reflects on individual's ability and aptitude, for the gifted and talented education in informatics. Therefore, in this paper, we suggest stepwise enrichment curriculums that enables the gifted and talented students to be equipped with creative problem-solving skills and computational thinking abilities. In this regard, at first, The problem with existing research and educational institutes for the gifted and talented in informatics were analyzed. Next we developed a concrete stepwise enrichment curriculum in accordance with the practical educational objectives of the gifted and talented in informatics.

• Korean Journal of Social Welfare
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• v.39
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• pp.41-73
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• 1999

There are few studies on the estimation of social expenditures, since few efforts so far have been made to introduce and study social expenditures based on OECD standards. Previous studies focused on the total amount based on ILO and IMF criteria, which is limited in the estimation of social expenditures by function and in detail. Accordingly, government and research institutes have faced difficulties from the lack of relevant statistics in establishing policies and performing research. This study, therefore, aims to develop an estimation model for social expenditures, and define the scope of the social security scheme and finances. In the process of developing this model, the accuracy of the scale of social expenditures estimated according to OECD criterion was also considered. Specifically, efforts were made to secure transparency of estimation through omission or duplication of expenditures. The estimation of Korea's social expenditures is applied to this model. The estimates for the year 1997 revealed 30,918.2 billion Won or 6.82% of GDP, which is a 20.8% increase per annum.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1195-1202
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• 2010

When modelling lots of induction motors to design and configure an engine room simulator, the 2 parameters equivalent circuit has many practical benefits as it reduces working hours considerably without requiring complicated technical data from makers except the ratings of motors. The basic properties such as torque and load current are shown well matched with real cases by this method, but almost the only drawback of 2 parameters circuit is that it reveals inherently higher power factor in the whole operation range due to disregarding the exciting current of the induction motor to maximize the simplification. This paper suggests a modelling module as a practical tool to compensate the power factor by inserting a virtual compensation current into the load current from 2 parameters equivalent circuit, and the simulated results show satisfactory outputs and the improved power factor indication by performance curves when compared to the cases of 2 parameters-equivalent circuit.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.555-561
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• 2014

Data processing service via internet help user to get the GNSS data processing result more precise and easily. Thus, online data process system is operated and developed by various research groups and national. But this service is difficult to use in domestic cadastral survey. In this study, we developed the online data processing system for a domestic cadastral survey. This is calculated coordinate using NGII CORS(SUWN) fiducially. And use PPP technique by GIPSY-OASIS. If user choose the observation data which want to calculate the coordinate, then is uploaded to GIPSY-OASIS server through FTP. After upload is complete, server automatically calculate coordinate, and send the report about result using e-mail. And it takes 2 minutes runtime on the basis of the 3 sessions. To verify the result, we used the data on SOUL, JUNJ as compared with notified-coordinate from NGII. As a result, got the difference for east-west 1.4 cm, north-south -1.0 cm, vertical 0.5 cm.