• Earthquakes and Structures
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• v.6 no.3
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• pp.251-266
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• 2014

Dynamic analyses for a suite of ground of motions were conducted on concrete gravity dam sections to examine the earthquake induced stresses and effective damping. For this purpose, frequency domain methods that rigorously incorporate dam-reservoir-foundation interaction and time domain methods with approximate hydrodynamic foundation interaction effects were employed. The maximum principal tensile stresses and their distribution at the dam base, which are important parameters for concrete dam design, were obtained using the frequency domain approach. Prediction equations were proposed for these stresses and their distribution at the dam base. Comparisons of the stress results obtained using frequency and time domain methods revealed that the dam height and ratio of modulus of elasticity of foundation rock to concrete are significant parameters that may influence earthquake induced stresses. A new effective damping prediction equation was proposed in order to estimate earthquake stresses accurately with the approximate time domain approach.

• Proceedings of the Safety Management and Science Conference
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• 2003.11a
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• pp.315-321
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• 2003

Under WTO we are confronted with the upcoming of the infinite competition and the opening of education market. In order to meet such new changes, more and more university in education industry participate in the certification of ISO 14000. This paper presents an effective approach to obtain the ISO 14001 environmental management system, summarized as follows: First, the top manager should understand the environmental problems and motivate all personnels. Second, a systematized environmental management system should be constructed in accord with actual circumstances of firms, and should be improved continuously by means of effective operation, internal audit and management review. Third, an environmental policy should be published, the environmental programs should be established following an environmental objective, target and they should be monitored regularly.

• Journal of Korean Neurosurgical Society
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• v.40 no.1
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• pp.6-10
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• 2006

Objective : The purpose of this study is to evaluate the surgical outcomes of bifrontal interhemispheric[BIH] approach and compare them to those of the pterional approach for the treatment of craniopharyngioma. Methods : Seventeen patients had their first operation for the resection of craniopharyngiomas between 2000 and 2004 at our medical center. Eleven patients who had the pterional approach and 6 with the BIH approach were enrolled. The age range at the time of surgery was 5 to 80 years [mean age 35.6 years old]. The presenting symptoms were visual disturbance increased intracranial pressure in 5 patients. Results : The tumors were totally removed in 3 [27 %] and subtotally in 8 [73 %] patients with the pterional approach. Total tumor removal was achieved in 5 out of 6 [83%] patients by the BIH approach, except improved in 4 [36 %] patients treated with the pterional approach and in all patients treated by the BIH approach. Conclusion : The BIH approach for craniopharyngioma surgery may be an effective and safe approach for tumors that extend outside of the sellar-suprasellar region with acceptable outcomes.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.595-599
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• 2003

For implementation of the strut-tie model approach to the practical analysis and design of structural concrete, the effective strengths of concrete struts in a strut-tie model, which have a crucial effect on the determination of strut and tie forces and the validity verification of strut-tie model's geometric compatibility condition, have to be determined accurately. In this study, the validity of the methods for determining the effective strengths of concrete struts was evaluated by conducting the strut-tie model analyses of the three reinforced concrete deep beams tested to failure with the effective strengths of concrete struts obtained from the suggested determination methods.

• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.573-588
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• 2023

Purpose: This study presents a research approach that utilizes deep reinforcement learning to construct optimal portfolios based on the business cycle for stocks and other assets. The objective is to develop effective investment strategies that adapt to the varying returns of assets in accordance with the business cycle. Methods: In this study, a diverse set of time series data, including stocks, is collected and utilized to train a deep reinforcement learning model. The proposed approach optimizes asset allocation based on the business cycle, particularly by gathering data for different states such as prosperity, recession, depression, and recovery and constructing portfolios optimized for each phase. Results: Experimental results confirm the effectiveness of the proposed deep reinforcement learning-based approach in constructing optimal portfolios tailored to the business cycle. The utility of optimizing portfolio investment strategies for each phase of the business cycle is demonstrated. Conclusion: This paper contributes to the construction of optimal portfolios based on the business cycle using a deep reinforcement learning approach, providing investors with effective investment strategies that simultaneously seek stability and profitability. As a result, investors can adopt stable and profitable investment strategies that adapt to business cycle volatility.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1553-1556
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• 1991

This paper deals with a problem on the selection of alternative tools in a flexible manufacturing system (FMS) where a lot of tools are required to produce a large variety of product items. An approach using branch and bound method is proposed to minimize a total number of tools required through the optimal use of the alternative tools. In this approach, tools are initially divided into tool subgroups based on graph theory for the purpose of the effective search of the optimal solution. A small example is also presented to highlight the effectiveness of the proposed approach.

• Steel and Composite Structures
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• v.5 no.1
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• pp.71-86
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• 2005

Based on the test data of Nippon Steel Corporation, the formulas for calculating mechanical properties of fire-resistant (FR) steel at elevated temperatures have been established. A practical approach for fire safety design of FR steel members, including axially compressed members, flexural members and eccentrically compressed members, is developed in this paper. Compared with the full-scale specimen experiments and FEM numerical analysis, this practical approach for fire safety design of FR steel members is demonstrated to be effective and precise.

• Structural Engineering and Mechanics
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• v.21 no.4
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• pp.423-435
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• 2005

A modal approach is proposed for dynamic analysis of concrete arch dam-reservoir systems in frequency domain. The technique relies on mode shapes extracted by considering the symmetric parts of total mass and stiffness matrices. Based on this method, a previously developed program is modified, and the response of Morrow Point arch dam is studied for various conditions. The method is proved to be very effective and it is an extremely convenient modal technique for dynamic analysis of concrete arch dams.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.391-396
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• 2003

The concrete corbels consist of various failure mechanisms such as the yielding of the tension reinforcement, the crushing or splitting from compression concrete struts, and localized bearing or shearing failure under the loading plate. However, predicting those failure mechanisms is very difficult. In this study, the ACI 318-02, the softened strut-tie model approach, and the nonlinear strut-tie model approach are applied to ultimate strength analysis of normal strength concrete corbels tested to failure. From the result of the analysis, an effective analysis and design method of normal strength concrete corbels is suggested.

• Korean Journal of Bronchoesophagology
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• v.6 no.2
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• pp.143-146
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• 2000

Cystic lesion which is located in vallecular area is sometimes symptomatic and need surgey. But surgical route to this area is divided external approach into internal one. Internal approach via transoral route with suspension laryngoscope can avoid disadvantages of external approach but conventional laryngoscope is not suitable for this type of procedure. We used Steiner laryngopha-ryngoscope in surgery for vallecular cyst and we could excise cyst easily. Of 20 cases, complete excision was tried in 18 cases and marsupialization in 2 cases. Recurrence was 1 case. We suggest that surgery using laryngopharyngoscope is effective in treating cyst which is located in vallecular area.