• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.5
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• pp.445-454
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• 2020

Non-breakaway crashworthy sliding posts move rigidly with a vehicle in the early stage of vehicle impact. During this stage, a vehicle imparts its linear momentum to the post, experiencing first-stage speed loss followed by second-stage loss from the crush of the energy-absorbing pipe (EAP) installed under the guide rail. An EAP is the key element of a crashworthy sliding post and should be confined to the post foundation. This paper covers the development of an EAP for a sliding post of 507 kg, which is a sliding post type frequently used in Korea for cantilever signs. Detailed explanations of the designs for an EAP structure using LS-DYNA impact simulation are given, and the crashworthiness of the systems are confirmed through crash tests. The EAP presented in this paper can accommodate impacts from 0.9 ton-60 km/h to 1.3 ton-80 km/h, and is applicable to foundations up to 2.7 m in length.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.655-656
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• 2018

In the 21st century, smart phones have become indispensable items in everyday life. Users get various information from smartphone, and location information such as map is one of them. It is a matter of course that there is a high need for an app that displays information about the user in detail on a smartphone that always carried around wherever it goes. However, in many cases, the current map or navigation is not suitable for selecting only the desired information group. In this project, I want to develop it with Android studio so that make users to get the information of the area easily and quickly in daily life. And it is designed to make it more convenient for users by creating a server with raspberry pie.

• The Journal of Society for e-Business Studies
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• v.12 no.4
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• pp.1-15
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• 2007

Traceability links are logical links between individual requirements and other system elements such as architecture descriptions, source code, and test cases. These are useful for requirements change impact analysis, requirements conflict analysis, and requirements consistency checking. However, establishing and maintaining traceability links places a big burden since complex systems have especially yield an enormous number of various artifacts. We propose a feature-oriented requirements tracing method to manage requirements with cost benefit analysis, including value consideration and intermediate catalysis using features. Our approach offers two contributions to the study of requirements tracing: (1)We introduce feature modeling as intermediate catalysis to generate traceability links between user requirements and implementation artifacts. (2)We provide value consideration with cost and efforts to identify traceability links based on prioritized requirements, thus assigning a granularity level to each feature. In this paper, we especially present the results of a case study which is carried out in Apartment Ubiquitous Platform to integrate and connect home services in an apartment complex in details.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.2
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• pp.103-110
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• 2017

In this paper, it is covered in detail the process of generating structural alternatives with geometry change and its optimization by StrAuto. The main roof structure of the Exhibition Center is modelled parametrically and the optimal alt is derived by observing volume changes according to geometry change of main roof truss. Existing studies performed optimization process through sections and properties due to the limitations of shape change, but this study have meaning of performing the optimization with geometry changes which is the most critical skills of StrAuto. By the process of securing a sufficient margin by geometry changes and reducing volume with the optimization of sections, despite of a partial optimization of large space structure, it could be reduced by 11.7% of the total volume.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.4
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• pp.312-333
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• 2005

SIP(Session Initiation Protocol) has been proposed for session control protocol of Internet multimedia communication system like VoIP(Voice over IP). SIP has complicated session control steps to support various kinds of audio and video formats and to assure service quality of real time data communication. Up until now, existing protocol analyzers can not provide such detailed information of SIP based communication system. In this paper, therefore, we propose a new protocol analyzer as a tool that can analyze and diagnose SIP based multimedia communication system throughout the session initiation, data exchange and session change steps. The propose traffic analyzer, which is called STAT(SIP based Traffic Analysis Tool), Is implemented on Winder's environment so that it is generally usable and extensible. Since STAT analyze low level packets captured via Ethernet broadcasting property, it is able to provide session status and real time traffic monitoring information without any affection to the communication system. The STAT which is implemented in this paper. therefore, is expected to be a useful tool for developing and managing of a SIP based multimedia communication system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.618-624
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• 2017

In Seoul and most metropolitan cities, urban trains are delayed due to high congestion during commute times. The delay effect of passengers boarding and disembarking is also significant. In this study, a wide passenger door system was developed as a way to improve the scheduled speed of urban trains by decreasing the passengers' flow time. The door size was defined experimentally to shorten the entrance time. The optimum door size was also determined to improve the stop precision performance of the train while considering the interference effect with peripheral devices. Because the change in door size changes the structural characteristics of the vehicle, the structural stability of a train was analyzed numerically. A prototype of the wide door system was made, and the proposed design was verified using functional and endurance tests. The systematic development process can be used as design data for door size definition and system production when applying a wide door to improve the scheduled speed.

• Current Industrial and Technological Trends in Aerospace
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• v.5 no.1
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• pp.75-92
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• 2007

2002년 프론티어사업의 일환으로서, 10년간 1200억의 예산으로 미래형 신개념비행체 기술개발사업을 시작한 스마트무인기사업은, $2002{\sim}2003$년 수행한 개념연구를 통해 미래형 신개념 고속 수직이착륙 항공기 개념으로서 틸트로터 개념을 선정하고 이의 개발에 매진하고 있다. 사업단에서는 우선, 항공 선진국에서 지난 반세기 동안 시행한 다양한 비행체 개념연구결과에 대해 자체적인 비교 분석 및 국제공동 연구를 근간으로하여, 당시 틸트로터에 필적하는 가능성을 보였던 스탑트로터(보잉사), 복합자이로콥터(카터콥터사) 개념이 아닌, 틸트로터 비행체의 기술개발을 결정하게 되었다. 각각의 비행체 개념이 갖는 위험성과 도전성, 그리고 소요기술, 설계특성, 개발 위험도 등에 대한 면밀한 분석을 기초로 한 사업단의 체계적 의사결정은 주효했다. 스탑트로터개념은 비행시험의 잇단 실패와 지연/잠정 중단사태가 이어졌고, 복합자이로콥터 또한 잇단 비행사고로 2002년 기록한 148kts를 능가하는 고속성능 시현에 지금까지 실패함으로써, 실용화 가능한 고속수직이착륙기로서의 검증을 위해서는 해결해야할 기술적 과제가 많이 남아있음을 보여주고 있다. 반면, 틸트로터 개념의 경우 V-22의 설계 수정형에 대한 성공적인 비행시험완료 및 인증획득으로 전면양산승인이 2005년 결정되어 458대가 (미해병대(360), 해군(48), 공군(50)) 납품될 예정이고, 2010년 인증획득을 목표로 민수용으로 개발중인 BA609의 순조로운 비행시험진행, 무인기로 개발된 Eagle Eye 기술시현기의 비행 시험성공과 2003년 미 해양경찰청으로부터 Deep Water 프로그램의 장거리 순찰임무 주력기종 선정과 같이 군용, 상용, 무인용 고속 수직이착륙 시장의 전 방위적 진입이 현실화되고 있다. 이에 따라 항공업계의 반응은 2가지 방향으로 나뉘고 있다. 하나는 유럽의 ERICA 프로그램과 같이 틸트로터 기술 개발을 서두르자고 주장하는 방향이고, 다른 하나는 시콜스키의 X2 프로그램과 같이 틸트로터와는 차별화된 독자적인 고속 수 직이착륙 비행체 개념 개발을 시도하는 것이다. 이러한 배경으로 국내 독자적인 기술력으로 지난해까지 일구어낸 성공적인 스마트무인기 상세설계 종료 및 축소형 비행체 전환비행성공은 그 의의가 매우 크다고 할 수 있다. 본 논문은 틸트로터 개발사를 통해, 신개념 비행체 개발의 어려움과 교훈을 알아보고, 세계에서 2번째로 틸트로터 기술을 개발하고 있는 스마트무인기 사업의 현황과 기술적 특징 및 의의의 정리, 그리고 틸트로터의 대안으로 진행중인 새로운 고속 VTOL 비행체 연구현황에 대한 소개 와 간단한 기술적 평가를 포함시켰다.

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.503-514
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• 2011

In this research, the seismic connection details for two concrete-filled U-shape steel beam-to-H columns were proposed and cyclically tested under a full-scale cruciform configuration. The key connecting components included the U-shape steel section (450 and 550 mm deep for specimens A and B, respectively), a concrete floor slab with a ribbed deck (165 mm deep for both specimens), welded couplers and rebars for negative moment transfer, and shear studs for full composite action and strengthening plates. Considering the unique constructional nature of the proposed connection, the critical limit states, such as the weld fracture, anchorage failure of the welded coupler, local buckling, concrete crushing, and rebar buckling, were carefully addressed in the specimen design. The test results showed that the connection details and design methods proposed in this study can well control the critical limit states mentioned above. Especially, the proposed connection according to the strengthening strategy successfully pushed the plastic hinge to the tip of the strengthened zone, as intended in the design, and was very effective in protecting the more vulnerable beam-to-column welded joint. The maximum story drift capacities of 6.0 and 6.8% radians were achieved in specimens A and B, respectively, thus far exceeding the minimumlimit of 4% radians required of special moment frames. Low-cycle fatigue fracture across the beam bottom flange at a 6% drift level was the final failure mode of specimen A. Specimen B failed through the fracture of the top splice plate of the bolted splice at a very high drift ratio of 8.0% radian.

• Journal of Information Management
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• v.37 no.2
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• pp.1-20
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• 2006

It has lately been recognized that the sharing and exchanging of the research results information is the critical factor to improve the research productivity. So many institutions are planning or developing the information systems which provide the research information services for researcher. But it has very difficulty in integrating the research resources information due to the dispersion and heterogeneity in data sources, and semantic and structural difference in describing data. We propose the semantic web based methodology and conceptual framework for raising the interoperability of metadata about research results information, which will support the integration of the distributed research data for information services in the end. We first introduce the ontology which is developed based on Standard Metadata of Research Results Information published by STISC. Then to show the applicability in real-world environment, we express the metadata of research information in RDF/RDFS according to ontology. Finally we proposed the conceptual architecture of research information service system which shows the main components, the functional requirements, and the principal and design direction at implementing the system.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.105-112
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• 2017

A lot of piping systems have been used from nuclear power systems to water supply systems. The maintenance of the piping systems is needed to ensure proper operation of the piping systems. Failure of the large pipe systems especially such as KDHC(Korea District Heating Corporation) can be a matter directly related to the enterprise productivity and profitability. It can also lead to very important issues in promoting public safety and convenience. Therefore a method of quick and safety repairs have been emerged as the most important problem. In this study, freezing seal isolation method using liquid nitrogen cryogenic refrigerant was developed for the maintenance of a pre insulated heat transport pipe of KDHC with a diameter of 300 mm. In this study, by employing computational analysis techniques we performed the flow and heat transfer analysis for the targeted pre insulated heat transfer pipe and freezing seal jacket(ice-Plug) and have selected for optimal system. The detailed design model based on the results of the computational analysis finally was produced. A laboratory-scale test apparatus were designed and the freezing seal isolation self-test carried out. Also the performance assessment tests in the test bed of KDHC were carried out for on-site application.