• Bulletin of the Korean Chemical Society
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• 제19권12호
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• pp.1342-1346
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• 1998

The dehydrogenation of ethylbenzene with carbon dioxide has been carried out over ZSM-5 zeolite-supported iron oxide catalyst as well as commercial catalyst (K-Fe2O3) and unsupported iron oxide (Fe3O4) for comparison. In the dehydrogenation over the ZSM-5 zeolite-supported iron oxide catalyst, ethylbenzene is predominantly converted to styrene by an oxidative pathway in the presence of excess carbon dioxide. Carbon dioxide in this reaction is found to play a role as an oxidant for promoting catalytic activity as well as coke resistance of catalyst. On the other hand, both of commercial catalyst and unsupported Fe2O4 exhibit considerable decrease in catalytic activity under the same condition. It is suggested that an active phase for the dehydrogenation with carbon dioxide over ZSM-5 zeolite-supported iron oxide catalyst would be rather a reduced and isolated magnetite (Fe3O4)-like phase having oxygen deficiency in the zeolite matrix.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.649-655
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• 2009

Traffic safety and vibration serviceability of a railway bridge set a limitation to the application of long-span cable supported bridges even though the design trend of the bridge becomes longer and lighter. In the case of high speed railway, it becomes more severe for the high speed of the train and resonance of the structure. Therefore, the cable supported bridge does not exist in Korea high speed railway until now. On the other hand, in recent, Italia, Japan and China do design and construct the long-span cable supported bridges for high speed railway recently with overcoming of traffic safety and passenger comforts. In the present study, prior to analysis of traffic safety and passenger comforts, a extradosed bridge for common railway is re-designed for high speed railway. The difference of member forces and displacements by design live load, the difference of impact coefficient and variable stresses of cables are investigated.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.503-508
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• 1997

The effect of rotary inertia of concentrated masses on the natural vibration of the simply supported-simply supported fluid conveying pipe has been studied. For the analysis Galerkin's method is used fer transformation of the governing equation to the eigenvalue problem and the natural frequencies and mode shapes for the system have been found. Introduction of rotary inertia results in lots of change on the natural frequencies and mode shapes and its effect is highly noticed at the higher natural frequencies and mode shapes. Consideration of rotary inertia results in much decrease on the natural frequencies and its neglect could lead to erroneous results.

• Structural Engineering and Mechanics
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• 제68권6호
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• pp.713-720
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• 2018

In this paper a new numerical method to determine the elastic curve of the simply supported beams of variable cross-section is demonstrated. In general case it needs to solve linear or small nonlinear second order differential equations with prescribed boundary conditions. For numerical solution the initial values of the slope and the deflection of the end cross-section of the beam is necessary. For obtaining the initial values a lively procedure is developed: it is a special application of the shooting method because boundary value problems can be transformed into initial value problems. As a result of these transformations the initial values of the differential equations are obtained with high accuracy. Procedure is applied for calculating of elastic curve of a simply supported beam of variable cross-section. Results of these numerical procedures, analytical solution of the linearized version and finite element method are compared. It is proved that the suggested procedure yields technically accurate results.

• Educational Technology International
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• 제23권1호
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• pp.41-66
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• 2022

Vocabulary learning plays an important role in language learning. This study explored a new paradigm based on social networking site (SNS) supported collaborative learning for vocabulary learning. SNS supported collaborative learning (SSCL) can effectively promote learners' engagement, interest and motivation by providing a more communicative and interactive environment. However, vocabulary learning studies on SSCL mainly focused on the effectiveness and influencing factors, lacking specific instructional strategies. Therefore, this study aims to develop instructional strategies that guide instructors to create an SSCL environment for facilitating vocabulary learning. The final instructional strategies are composed of three stages according to the course process, consisting of 8 general strategies and 21 specific guidelines. The content validity was ensured by four experts in the field of educational technology. The instructional strategies were then applied in an actual classroom with 16 students. The positive responses from the instructor and learners indicated that SSCL can be reasonably incorporated into the current curriculum to provide effective learning opportunities and to promote learners' vocabulary learning.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.229-233
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• 2011

Recently, the scale of buildings has been increasing because of the high-rise trend and complexity of underground spaces. A significant number of steel structures have therefore been adopted for building construction. Since workers need to work in high places to install steel beams, many industrial accidents easily occur during steel-frame work. Furthermore, considering the increasing trend of building steel structures, the safety of the workers during the steel beam erection work is of concern. To improve the safety, a new type of joint, located between the steel column and beam, which can eliminate the need for working at the elevated height during steel beam erection has been developed in Korea. Using the newly developed technology in the construction field, the safety performance needs to be evaluated. This study presented the safety evaluation approach for the newly developed technology from the literature review, and applied the method to a self-supported steel joint. The result showed that applying the self-supported steel joint improved the safety of the steel erection work in terms of working posture, working environment, and risk exposure time.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.586-590
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• 2011

This paper presents the case study of the CE by collaborative system and proposes a model of the CM group for the cable supported bridge. The cable supported bridges have a large project scale and need a high level of construction method. Therefore an advanced construction management system is required for successful completion of project. The construction management (CM) group which control design management, construction plan, subcontract, technical support and R&D is organized for the cable supported bridge project. The CM group established a collaborative system with construction site and drew an effective management of cost, process, quality, safety for each project. Furthermore, the CM group established the procedure of construction management based on the construction engineering (CE) items and performed the project management on the construction phase. Efficiency of cost reduction and site control is maximized by using a collaborative system.

• Bulletin of the Korean Chemical Society
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• 제26권3호
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• pp.373-374
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• 2005

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.185-186
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• 2006

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1297-1299
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• 2005