• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.348-354
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• 2003

An analysis of the dynamic behavior between disk and roller has been performed when the torque is transmitted to toroidal IVT (Infinitely Variable Transmission). The contact area, shape and pressure with elliptical shapes between disk and roller are computed as the transmission ratios are changed. This study will give the information of contact shapes between roller-input dist and roller-output disk which are working under the most severe condition. The computed results are expected to guide the design criteria for the enhanced endurance li(e. Furthermore, the investigation of contact behaviors is very crucial to develop the traction oil that the efficiency of IVT system is most dependent on.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.304-311
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• 1998

An algorithm to enhance spectra matching of acceleration time history used in the seismic analysis of nuclear power plants(NPP) is proposed. The new scheme provides the solution on the highly fluctuating and over conservatism problems that happened in order to satisfy design spectrum enveloping criteria in the traditional method. To obtain optimized spectrum for a time history, a spectrum matching procedure that adapts a system identification technique is also developed. The algorithm also introduces maximum displacement control, baseline correction, clipping and raising of maximum peak of time history, and power spectral density (PSD) control of time history. It is verified through numerical examples that this new scheme can definitely generate acceleration time history, closely matching the target spectra and satisfying other stipulated requirements.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.205-212
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• 2021

Offshore jacket structures generally comprise steel members, and the safety standard for jacket structures typically focuses on the steel components. However, large amounts of concrete grouting is filled in the legs of the Gageocho jacket structure to aid in the recovery from typhoon damage. This paper proposes a safe and lightweight design for the Gageocho ocean research station comprising steel members instead of large amounts of concrete reinforcement in the legs. Based on the actual design, the structural members are grouped according to their functional roles, and the inner diameter of the cross-section in each design group is defined as a design variable. Structural optimization is carried out using a genetic algorithm to minimize the total weight of the structure. To satisfy the conservative safety standards in the offshore field, both the maximum stress and the unity check criteria are considered as design constraints during optimization. For enhanced safety confidence, extreme environmental conditions are assumed. The maximum marine attachment thickness and the section erosion in the splash zone are applied. Additionally, the design load is defined as the force induced by extreme waves, winds, and currents aligned in the same direction. All the loading directions surrounding the structure are considered to design the structure in a balanced and safe manner. As a result, compared with the current structure, the proposed structure features a 45% lighter design, satisfying the strict offshore safety criteria.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.63-69
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• 2017

The middleware in the IoT system is software that acts as a messenger to connect and exchange data between humans and objects, objects and objects. IoT middleware exists in various forms in all areas, including hardware, protocol, and communication of different kinds, which are different in form and purpose. However, IoT middleware exists in various forms across different areas, including hardware, protocol, and communication of different types and purposes. Therefore, even if the system is designed differently for each role, it is necessary to strengthen the security in common. In this paper, we analyze the structure of IoT middleware using Service Oriented Architecture(SOA) approach and design system security requirements based on it. It was defined: Target Of Evaluation(TOE) existing system development method and the object is evaluated by Common Criteria(CC) for verification based otherwise. The proposed middleware system will be correlated with the security problem definition and the security purpose, which will be the basis for implementing the security enhanced IoT system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.339-349
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• 2006

The purpose of this study is to investigate the seismic behavior of circular reinforced concrete bridge piers with confinement steel and to provide the data for developing improved seismic design criteria. Fourteen circular reinforced concrete bridge piers were tested under a constant axial load and a cyclically reversed horizontal load. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. In the companion paper, the proposed numerical method for the seismic performance assessment of circular reinforced concrete bridge piers with confinement steel is verified by comparison with experimental results.

• International Journal of Safety
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• v.3 no.1
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• pp.53-58
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• 2004

SMART-P is a promising advanced small and medium category nuclear power reactor. It is an integral type reactor with a sensible mixture of new innovative design features and proven technologies aimed at achieving a highly enhanced safety and improved economics. The enhancement of the safety and reliability is realized by incorporating inherent safety improving features and reliable passive safety systems. The improvement in the economics is achieved through a system simplification, and component modularization. Preliminary safety analyses on selected limiting accidents confirm that the inherent safety improving design characteristics and the safety system of SMART-P ensure the reactor's safety. SMART-P is an advanced integral pressurized water reactor. The purpose of this study is for the safety analysis of the steam generator module pipe break for the SMART-P. The integrity of the fuel rod is the major criteria of this analysis. As a result of this analysis, the safety of the RCS and the secondary system is guaranteed against the module pipe break of a steam generator of the SMART-P.

• Advances in environmental research
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• v.3 no.3
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• pp.253-281
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• 2014

The quest for enhanced thermal comfort for dwellings encompasses the holistic utilization of improved building fabric, impact of weather variation and amongst passive cooling design consideration the provision of appropriate ventilation and shading strategy. Whilst thermal comfort is prime to dwellings considerations, limited research has been done in this area with the attention focused mostly on non-dwellings. This paper examines the current and future thermal comfort implications of four different standard construction specifications which show a progressive increase in thermal mass and airtightness and is underpinned by the newly developed CIBSE adaptive thermal comfort method for assessing the risk of overheating in naturally ventilated dwellings. Interactive investigation on the impact of building fabric variation, natural ventilation scenarios, external shading and varying occupants' characteristics to analyse dwellings thermal comfort based on non-heating season of current and future weather patterns of London and Birmingham is conducted. The overheating analysis focus on the whole building and individual zones. The findings from the thermal analysis simulation are illustrated graphically coupled with statistical analysis of data collected from the simulation. The results indicate that, judicious integrated approach of improved design options could substantially reduce the operating temperatures in dwellings and enhance thermal comfort.

• Steel and Composite Structures
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• v.32 no.4
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• pp.455-466
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• 2019

Despite the rapid advancement in computing resources, many real-life design and optimization problems in structural engineering involve huge computation costs. To counter such challenges, approximate models are often used as surrogates for the highly accurate but time intensive finite element models. In this paper, surrogates for first-order shear deformation based finite element models are built using a polynomial regression approach. Using statistical techniques like Box-Cox transformation and ANOVA, the effectiveness of the surrogates is enhanced. The accuracy of the surrogate models is evaluated using statistical metrics like $R^2$, $R^2{_{adj}}$, $R^2{_{pred}}$ and $Q^2{_{F3}}$. By combining these surrogates with nature-inspired multi-criteria decision-making algorithms, namely multi-objective genetic algorithm (MOGA) and multi-objective particle swarm optimization (MOPSO), the optimal combination of various design variables to simultaneously maximize fundamental frequency and frequency separation is predicted. It is seen that the proposed approach is simple, effective and good at inexpensively producing a host of optimal solutions.

• The Journal of Industrial Distribution & Business
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• v.15 no.5
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• pp.29-37
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• 2024

Purpose: Numerous prior researchers have identified only that sustainable management of ESG factors promotes business value creation and shapes enhanced innovation performance. This study aims to determine the positive relationships between ESG management and economic development, focusing on the mutual benefits and risks and the various stakeholders involved in managing change. Research design, data and methodology: This study selected the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement as a key methodology. Literature search used the following databases: Web of Science, Scopus, and Google Scholar. The quality assessment criteria for selected prior studies ranged from issues like design, sample size and the representativeness of the subjects, validity of measurements, and analytical strength. Results: The findings of this study indicates that there are four critical solutions for economic development triggers using ESG strategy, such as (1) ESG and Innovation-Driven Growth, (2) ESG and Human Capital Development, (3) ESG and Operational Efficiency, (4) ESG and Market Opportunities. This study insists that public-private partnerships are critical for enhancing sustainable economic development and meeting the needs of society. Conclusions: It is, therefore, important for governments and policymakers to play a critical role in setting the proper framework that allows for the uptake of ESG and an enabling environment for sustainable economic development.

• Tunnel and Underground Space
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• v.32 no.1
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• pp.59-77
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• 2022

Currently, the design reference temperature of the buffer material for disposing of high-level radioactive waste is less than 100℃, so if the heat dissipation capacity of the buffer material is improved, the spacings of the disposal tunnel and the deposition hole in the repository can be reduced. First of all, this study tries to analyze the criteria for thermal-hydraulic-mechanical performance of the buffer materials and to investigate the researches regarding the enhanced buffer materials with improved thermal conductivity. First, the thermal conductivity should be as high as possible and is affected by dry density, water content, temperature, mineral composition, and bentonite type. the organic content of the buffer material can have a significant effect on the corrosion performance of a canister, so the organic content should be low. In addition, hydraulic conductivity of the buffer material should be less than that of near-field rock and swelling pressure should be appropriate for buffer materials to function properly. For the development of enhanced buffer materials, additives such as sand, graphite, and graphite oxide are typically used, and a thermal conductivity can be greatly improved with a very small amount of graphite addition compared to sand.