• Journal of the Korea Society of Computer and Information
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• v.26 no.9
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• pp.143-153
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• 2021

In this paper, we propose "flexible routing with flex" to provide fast delivery by using the flexible routing for the delivery vehicle and crowd-shipper named flex. To this end, we have introduced an algorithm that can build the delivery plan for delivery vehicles and flexes. The introduced algorithm uses the 2-opt algorithm to construct routes with low complexity and acceptable quality, and the revised saving algorithm to assign customer orders to the flex. The algorithm allows the vehicle and the flex to function complement each other without separating the delivery vehicle from the flex. The experiments consider the 3 different instances named Random, Mixed, Cluster, and show that "the flexible routing with flex" has a better result than "vehicle only". The sensitivity analysis of the flex cost and time penalty shows "the flexible routing with flex" can provide better service not only to the customers who are serviced by flex but also to the customers who are serviced by the delivery vehicle.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.183-194
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• 2005

In the previous construction method of continuous preflex composite girder bridge, we raised the inner support, and cast slab concrete innegative moment section, then lowered it to introduce compressive force in the slab. There were a few problems in the process such as the time required in raising the support and the bending of the camber. Therefore, this paper represents an improved construction method of continuous preflex composite girder by only moving downward the inner and outer supports to figure out problems in previous construction method. This paper proposes a design formula to find a proper cross section of preflex girder.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.433-441
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• 2001

Thus study presents the basic concepts of 3 span continuous preflex composite beam of bridges by re-up down of supports and analysis relationship of between variables and stress of critical section. Also, it shows the pre-compression effects of re-up down of supports method by presenting the difference of between old section and new section got from new method. This study's new method makes more economic sections to be possible and when the sections designed with the existing method are used in the new method. efficient stress state is accomplished.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.198-200
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• 2022

In this paper, we are going to explain the development of a platform that can integrate and manage various sensors and data by applying IoT standard technology to a smart city where various services exist. The structure was designed to integrate and manage various data through platform development and process the collected data according to the service. By designing a platform based on the LwM2M standard technology, it is possible to provide a function that can accommodate various devices.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.691-698
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• 2014

This paper describes the manufacturing processes for a flexbeam and torque tube made of composite materials, along with the procedures for testing their basic properties. A flexbeam and torque tube can be considered to be key structural components of a bearingless rotor hub system. A hinge offset effect can be realized by a large elastic deformation and twist of the flexbeam, and the blade pitch control forces are transferred by the rotation of the torque tube. The basic property tests included bending and twist tests to determine the flap stiffness, lag stiffness, and torsion stiffness of the flexbeam, torque tube, and blade, and these tests were performed prior to starting the whirl tower test. In addition, the estimated results were compared with experimental data, and the calculations were found to be a good match for the analysis results and had a similar tendency. Through these results, we could confirm that a flexbeam and torque tube made of composite materials satisfied the structural stiffness requirements.

• 한국정보교육학회:학술대회논문집
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• 2008.01a
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• pp.192-197
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• 2008

초등학교 수학과 도형 학습은 매우 추상적인 분야로 직관적인 이해를 돕기 위해 다양한 구체적인 조작이 요구되는데, 그 중에서 컴퓨터를 활용한 도형 학습은 학생들의 구체물을 이용한 학습의 한계를 극복할 수 있는 장점이 있다. 특히 Flex와 Flash를 이용하면 입체도형의 가상물의 제작 및 동적인 학습은 물론 사용상의 제약이 적어 시,공간의 한계를 극복할 수 있다. 본 연구에서는 초등학교 수학과 제 7차 교육과정의 입체도형 영역을 분석하여 학습요소를 추출하고 플래시의 드로잉 메서드를 바탕으로 학습요소별로 속성과 메서드를 정의하고 클래스를 설계하여 입체도형 객체를 생성하고 플렉스의 컴포넌트로 구성된 학습 어플리케이션의 틀을 설계하여 입체도형 객체가 플렉스의 어플리케이션 내에서 사용이 가능하도록 설계 개발하였다. 본 연구가 갖는 의의는 첫째, 초등학교 수학과 수준에 맞는 속성과 메서드를 갖도록 개발한 입체도형 객체를 활용하여 학습자의 입체도형에 자유로운 탐구활동 기회를 제공하여 보다 직관적이고 구체적으로 도형학습을 할 수 있도록 돕는다. 둘째, 플렉스를 활용함으로서 학습자의 쉬운 접근을 돕고 학습 어플리케이션 틀을 활용하여 기존에 개발되어 있는 수학과 플래시 파일들을 활용한 다른 수학과 영역의 학습 어플리케이션 설계 및 개발의 시간과 노력을 단축시키는데 있다.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.697-705
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• 1997

The conventional preflex beams are designed by the method of paritial prestressing and allow the tensile stresses at the lower concrete of beams. As a consequence, most of preflex beams experience the tensile cracks under the service loads. This study was conducted to develop the most effective preflex beams, which do not allow tensile stress under the service load, by introducing additional prestressing called 'represtressing' at the lower concrete of beams. The objective of the study was accomplished by developing a computer analysis and design program and conducting experiments. Using the developed computer program, standard sections of the represtressed preflex beams were determined by computer modeling. In the experiment, two actual size of represtressed beams were tested under the imitated service loads. The results of test have shown that the performance of the represtressed preflex beams is generally excellent. A remarkable improvement was made in the design of preflex composite beams. Since the represtressed preflex beams(RPF) do not experience the tensile cracks under the service loads, the use of this beam for the bridge structures will lead to easy bridge maintenance and management. Furthermore, due to the low beam depth, high clearance and economical design can be realized in the bridge design using RPF.

• Journal of Digital Convergence
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• v.19 no.12
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• pp.311-320
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• 2021

This study aims to explore the applicability of the HyFlex Learning Model as a new form of early childhood education in the post-COVID-19 era. In order to achieve the purpose of this study, first, the current challenges of early childhood education and the form of early childhood distance education in Korea were examined. Second, after examining the outline and characteristics of the HyFlex Learning Model(HLM) and the application cases of overseas institutions, in particular, the cases of applying the HLM in overseas early childhood education institutions were reviewed. Third, things to consider when applying the HLM in the field of early childhood education in Korea were derived. As a result, the HLM was investigated to be applicable not only in higher education but also in early childhood education as a model that emphasizes the learner's choice, learner-centered/directed, and activity. In order to apply the HLM to the early childhood education field in Korea, several points to be considered were proposed. Finally, the contribution of this study and further study were suggested.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.109-110
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• 2013

국내에서 최초로 장스팬 프리플렉스 합성보에 대한 내화성능을 평가하고 그 결과를 분석하였다. 내화성능평가는 재하시험과 비재하시험을 대상으로 하였으며, 콘크리트 폭렬의 영향성과 뿜칠피복재의 단열효과에 의한 성능확보 요인을 분석하였다. 본 논문은 국내 최장 합성보의 내화구조 인정신청에 따른 성능확인 결과이며, 향후 다양한 합성보 개발에 참고가 될 수 있을 것으로 기대한다.

• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.125-135
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• 1998

This study presents a design method for three-span continuous preflex composite girder bridges (3S-PCB) which imposes prestresses in the negative moment region by lifting or lowering interior supports and the design method is automated by a computer program which incorporates optimal design procedure. The objective function for the design of 3S-PCB minimizes the cost of construction materials and the constraint functions represent the limited dimensions of the design section and the allowable stress for each structural member as given in the specifications. Optimal design procedure used in this study is a modification of existing sequential unconstrained minimization technique (SUMT), a numerical analyses procedure for two-span continuous preflex composite bridges. The optimized design sections determined for each span length are compared with those of simple preflex composite beams (SPCB) and the optimal girder depth is determined by defining the relationship between girder depth and construction material costs.