• International Journal of Concrete Structures and Materials
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• 제10권sup3호
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• pp.1-17
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• 2016

Recently, advanced transit systems are being constructed to reduce traffic congestions in metropolitan areas. For these projects, curved bridges with various curvatures are required. Many curved bridges in the past were constructed using aesthetically unpleasant straight beams with curved slabs or expensive curved steel box girders with curved slabs. Therefore, many recent studies have been performed to develop less expensive and very safe precast prestressed concrete (PSC) curved girder. One method of reducing the construction cost of a PSC curved girder is to use a reusable formwork that can easily be adjusted to change the curvature and length of a girder. A reusable and curvature/dimension adjustable formwork called Multi-tasking formwork is developed for constructing efficient precast PSC curved girders. With the Multi-tasking formwork, two 40 m precast PSC box girders with different curvatures were constructed to build a two-girder curved bridge for a static flexural test to evaluate its safety and serviceability performance. The static flexural test results showed that the initial cracking load was 1400 kN, exceeding the design cracking load of 450 kN. Also, the code allowed deflection of 50 mm occurred at a load of 1800 kN, verifying the safety and serviceability of the precast PSC curved bridge constructed using the multi-tasking formwork.

• 한국실내디자인학회논문집
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• 제16권1호
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• pp.126-134
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• 2007

This study researches the effectiveness of virtual experiences as an evaluation method in design. For the study, I researched the result on the spatial recognition before, abstracted visual objects and factors in recognition process and made up 43 inquiries for the evaluation through the experts group. Besides, set the analytical code between recognition factor and spatial constituents, made analysis the result from it. From April 1st to June 30th in 2004, the virtual model of educational place, college main building and city library was established as a subject of the research and studied the result. The methods that are used for the study are frequent analysis, T-test, reliability analysis, factor analysis etc. and SPSSWIN Package is used for the statistic analysis. There were two times of analysis on the evaluation to analyze the effect of virtual models on the web basis, one group evaluated the virtual building same as real and the other group evaluated the building site. Then analyzed the differences and correlation between the two. In result, college building, the first subject of study, and the second city library shows that made little differences between on the spot evaluation and virtual evaluation. Therefore, it is considered that the design evaluation with virtual model on the web basis has a vantage. But some problems founded that solved between preceding and present research through the feedback. It is as follows, 1. detection of problems that insufficience validity in the first survey. 2. found some not-validity inquiries. 3. detection of necessities that qualitative improvement and technical repletion in virtual environment.

• 정보보호학회논문지
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• 제25권4호
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• pp.905-914
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• 2015

정보보안솔루션은 구축 후 일반적인 유지관리 활동 외에 외부 위협요인(공격)으로부터 보안성을 지속시키기 위해, 악성코드 분석 및 보안업데이트, 보안정책관리, 위협/사고분석, 보안성 인증 효력 유지, 보안기술자문 등의 추가활동이 수반되지만, 제공된 서비스만큼의 대가를 적용받지 못하는 현실적 문제점이 상존한다. 이에, 본 연구에서는 국내 정보보안솔루션의 보안성 지속을 위한 서비스 현황을 분석하고, 정보보안솔루션의 특성을 고려한 보안성 지속 서비스 대가가 반영될 수 있는 정책적 방안을 제시한다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.247-250
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• 2007

There are three main kinds of service standards for 3G(Third-Generation) wireless communication as WCDMA, CDMA2000 and TD-SCDMA(Time Division-Synchronous Code Division Multiple Access). Compare with WCDMA and CDMA2000, TD-SCDMA system has distinguished technical characters. It is a TDD(Time Division Duplexing) based technology and deploys several advanced but in some respects complex technologies such as smart antenna, joint-detection and baton-handoff, etc. Therefore to analyze and design TD-SCDMA wireless network, it needs more efficient and systematic simulation tool. General simulation tool has so many analysis functions including path loss prediction, capacity and coverage analysis. For more suitable for TD-SCDMA, new additional technologies have to be implemented in simulation tool. Especially as the wireless network highly advancing focused on data service, it more needs to research and develop on the reliability of the simulation tool. In this paper, to give the concrete process and skill about how to implement TD-SCDMA simulation tool, we define the kinds of simulation tool and list basic analysis functions available for TD-SCDMA network design at first. And then we explain how to consider the effects of new technologies of TD-SCDMA and give the solutions about theses considerations.

• Computers and Concrete
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• 제16권1호
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• pp.49-65
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• 2015

It is hard to guarantee the strict synchronization of all the jacking-up points in the integral jacking of a large-span continuous box girder bridge. This paper took the Hengliaojing Bridge as background, which need jacking up as an object with 295m length and more than 10,000tons weight, adopted 3D software to calculate the unsynchronized jacking-up working conditions, and studied the relationships between the unsynchronized vertical difference and the girder's deformation behaviour. The aim is to verify the maximum value of the unsynchronized vertical difference, and guide the construction and ensure safety. The monitoring system with its contents is introduced corresponding to the analysis. The results of the deck relative elevations prove that it is difficult to avoid the deck torsional deformation for jacking different; especially the side span shows more deformations for its smaller stiffness. The maximum difference is smaller than the limited value with acceptable stresses in the sections. The jacking heights of the pier in each construction step are controlled regularly according to the design. The shifting of the whole bridge in longitudinal direction is smaller than in transverse direction. The several beginning steps are the key to adjust their support reactions. This study is one parts of the fundamental research for the code "Technical specification for bridge jacking-up and reposition of China". The whole synchronous jacking project of the main bridge set a world record by the World Record Association for the whole bridge jacking project with the longest span of the world.

• 해양환경안전학회지
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• 제22권3호
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• pp.268-277
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• 2016

This paper aims at presenting bunkering educational programs for LNG fueled ship taking into consideration existing similar education programs and safety systems at the international level in order to enhance both seafarers' and vessels' safety. Heavy fuel oil has typically been used as fuel of ship propulsion. The competitiveness of the fuel oil is recently getting weak in terms of cost and environmental aspects. Liquefied natural gas is introduced for ship propulsion in the maritime field as a new energy source replacing heavy fuel oil. In order to prepare for installation and operation of LNG fueled propulsion ship on board, International Maritime Organization has discussed this subject for about 10 years. As a result of the discussion on such ships in IMO, the International Code of Safety for Ships Using Gases or Other Low-Flash-Point Fuels entered into force on the year 2015. International organizations and several countries therefore drives actively entire researches and other businesses with a view to providing equipment and system of LNG bunkering. The systems are divided into ship-to-ship transfer, terminal / pipeline-to-ship transfer and truck-to-ship transfer. By adopting transfer system of LNG bunkering, many human resources will be needed in these areas on scene as well as on managing, operating, trading, finance, design of LNG bunkering industries. LNG bunkering is just in the beginning stage. Hence, this paper reviews and proposes professional educational programs of LNG bunkering in consideration of technical aspects of the safety system of LNG bunkering based on the types of bunkering systems.

• 한국강구조학회 논문집
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• 제26권5호
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• pp.473-483
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• 2014

건축구조기준에 따라 HSA800 강재의 합성기둥 적용시에는 실험 또는 해석적 방법을 통하여 적용의 타당성을 검증해야 한다. 이에 본 연구에서는 합성기둥으로 주로 사용되는 H형강 매입형, 각형강관 및 원형강관 충전형 합성기둥 단면을 대상으로 HSA800 강재를 적용한 단주압축실험을 실시하고, 이를 통하여 축방향 내력 및 건축구조기준의 합성기둥 설계압축강도 설계식 적용의 타당성을 평가하였다. 실험결과 매입형 합성기둥의 경우 HSA800 강재의 설계기준항복강도를 저감없이 사용하기 위해서는 건축구조기준의 설계압축강도 산정식의 조정이 필요한 것으로 나타났으며, 이를 위해 띠철근 간격 조정 및 콘크리트의 유효단면적 사용을 제안하였다. 충전형 합성기둥의 경우에는 각형, 원형충전강관 기둥 모두 별도의 강도 저감이나 설계압축강도 산정식의 조정 없이 사용이 가능할 것으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.343-358
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• 2008

Piles of a bridge pier are connected with a column through a pile cap(footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. This difference causes a change of the design method. Connection methods between pile heads and the pile cap are divided into two groups ; rigid connections and hinge connections. KHBDC(Korea Highway Bridge Design Code) has specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However some specifications prescribe that conservative results through investigations for both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which have very good quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) are unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the very large diameter drilled shaft and the pile cap for Incheon Bridge which will the longest bridge in Korea were investigated through the full modeling for rigid connection conditions.

• 한국해양공학회지
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• 제28권2호
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• pp.126-132
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• 2014

In this study, a method for analyzing the collision and interaction between ice bergy bits and a Mark III type liquid natural gas (LNG) carrier was considered, and the structural safety of a ship's hull and cargo containment system (CCS) was evaluated. In the analysis, a constitutive model implementing the strain rate dependant mechanical property was used to consider the typical material characteristics of ice rationally. A relatively simple and easy ice structure interaction analysis procedure, compared with the accurate but complicated FSI analysis scheme, was suggested. When the ice bergy bits collided with ship's side hull under the four assumed scenarios, the structural behaviors of the ship structure and LNG CCS were simulated by applying the suggested ice collision analysis procedure using the commercial hydro-code LS-DYNA. In addition, the effects of the shapes and colliding speed of the ice bergy bits on the ice-structure interaction and safety of the CCS were examined in detail.

• 정보보호학회논문지
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• 제30권2호
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• pp.197-212
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• 2020

가상 화폐와 전자 지갑의 등장으로 익명성을 기반으로 금전적 이득을 취할 수 있는 방법이 생김에 따라, 악성메일을 이용한 피싱과 악성코드의 전파가 지속적으로 증가하고 있다. 이에 대한 피해를 최소화하기 위해서는 인적 요소인 보안인식과 기술적 요소인 대응 능력을 고루 향상시켜야 하며, 이는 실전과 같은 악성메일 대응 훈련을 통해 향상될 수 있다. 본 연구에서는 실전과 같은 악성메일 훈련 수행을 고려한 모델을 제시하였다. 임직원들의 보안인식 향상을 위한 인식 제고 훈련과 악성메일 침투에 대한 대응 능력을 향상시키기 위한 탐지 및 대응 훈련으로 분류하여 목적에 맞는 훈련 시스템, 훈련용 악성코드의 주요 기능, 구현 및 위장 기법, 기술적 대책 우회 기법에 대해 서술하였다. 이 모델을 바탕으로 3년간 수행한 훈련 데이터를 수집하였으며, 훈련횟수, 훈련테마, 위장기법에 따른 결과 분석을 통해 훈련의 효과성을 연구하였다.