• East Asian Journal of Business Economics (EAJBE)
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• v.12 no.1
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• pp.35-42
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• 2024

Purpose: A railroad project is a complex system with large construction costs in the initial stage and ongoing operating costs over its lifecycle. Current railroad projects tend to be based on construction options, which leads to huge deficiencies in operating costs. This phenomenon results from a lack of appropriate tools to accurately estimate a railroad project's lifecycle costs. This study attempts to analyze the major components of railroad operating costs and to propose a decision-making system for analyzing the long-term lifecycle costs of railroad projects. Research design, data and methodology: We review the literature and analyze the current status of railroad operating costs in Korea and overseas. Based on previous projects, a framework for project options and operating costs is proposed. The framework is applied to actual railroad projects to demonstrate the validity of the model. Results: Case analysis shows that our framework is comprehensive in analyzing the primary aspects of railroad operating costs and plays an effective role in choosing various railroad project options. This study points out that the railway project operates inefficiently because estimating long-term costs without reflecting specific project options causes many errors. Conclusions: A major contribution of this study is the development of an improved framework for accurately estimating operating costs and providing policymakers and engineering firms with a holistic decision support system. Detailed components in estimating operating costs of the railroad business are discussed. And we present a decision-making tool that policymakers and private businesses can use in planning the railroad business.

• Journal of computational fluids engineering
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• v.20 no.2
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• pp.46-51
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• 2015

In this paper, we have developed numerical model for particulated flow through narrow slit using Eulerian-Granular method. Commercial software (FLUENT) was utilized as simulation tool and main focus was to identify the effect from various numerical options for modeling of solid particles as continuos phase in granular flow. Gidaspow model was chosen as basic model for solid viscosity and drag model. And lun-et-al model was used as solid pressure and radial distribution model, respectively. Several other model options in FLUENT were tested considering the cross related effect. Mass flow rate of the particulate through the slit was measured to compare. Due to the high volume density of the stacked particulates above the slit, effect from various numerical options were not significant. The numerical results from basic model were also compared with experimental results and showed very good agreement. The effects from the characteristics of particles such as diameter, angle of internal friction, and collision coefficient were also analyzed for future design of velocity resistance layer in solar thermal absorber. Angle of internal friction was found to be the dominat variable for the particle mass flow rate considerably. More defined 3D model along with energy equation for complete solar thermal absorber design is currently underway.

• Fashion & Textile Research Journal
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• v.20 no.5
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• pp.556-568
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• 2018

In this study, we surveyed the current status and sizing system of the custom dress shirts sold through online shopping, compared with the sizing system of the ready-made dress shirts. We tried to collect the information needed to make the well fitted dress shirts for middle-aged men from this study. The 17 online custom dress shirt brands were selected and the sales type, sales price, design options and size options of each brand were analyzed. The sizing systems of online custom dress shirt brands were compared with the sizing system of the 10 ready made dress shirt brands. The result showed that online custom dress shirts brands offered a variety of design options and size options to meet the consumers' individuality, taste and demand for good fit. In the ready-made brands, all 10 brands were using the same size notation system. In the same size designation, the difference in product size among the ready-made brands showed a tendency to be smaller than the online custom brands. The online custom brands had the different size notation system among brands. The size notation, the number of size designation and the size interval were different for each brand. Also, in the online custom brands, the product size among brands differed from each other in the same size designation. Therefore, the standardized size information and sizing system for middle-aged men that could be used as criteria when making the product size and pattern design in online custom brands were needed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.277-280
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• 2006

Most real world design evaluation and risk-based decision support combine quantitative and qualitative (linguistic) variables. Decision-making based on conventional mathematics that combines qualitative and quantitative concepts always exhibit difficulty in modelling actual problems. The successful selection process for choosing a design/procurement proposal is based on a high degree of technical integrity, safety levels and low costs in construction, corrective measures, maintenance, operation, inspection and preventive measures. However, the objectives of maximising the degree of technical performance, maximising the safety levels and minimising the costs incurred are usually in conflict, and the evaluation of the technical performance, safety and costs is always associated with uncertainties, especially for a novel system at the initial concept design stage. In this paper, a design-decision support framework using a composite structure methodology grounded in approximate reasoning approach and evidential reasoning method is suggested for design evaluation of machinery space of a ship engine room at the initial stages. It is a Multiple Attribute Decision-Making (MADM) or Multiple Criteria Decision Making (MCDM) framework, which provides a juxtaposition of cost, safety and technical performance of a system during evaluation to assist decision makers in selecting the winning design/procurement proposal that best satisfies the requirement in hand. An illustrative example is used to demonstrate the application of the proposed framework.

• Nuclear Engineering and Technology
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• v.29 no.4
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• pp.348-359
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• 1997

This paper reviews cooling aspects of the diverter system in Tokamak fusion devices with primary emphasis on the critical heat flux (CHF) issues for oater-cooled designs. General characteristics of four (4) coolant options for diverter cooling gases, oater, liquid metal, and organic liquid - are discussed first, focusing on the comparison of advantages and disadvantages of those options. Then results of recent studies on the high-heat-flux CHF of water at subcooled high-velocity conditions are reviewed to provide a general idea on the feasibility of the water-cooled diverter concept for future Tokamak fusion reactors. Water is assessed to be the most viable and practical coolant option for diverters of future experimental Tokamaks.

• Asia-Pacific Journal of Business
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• v.12 no.3
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• pp.343-359
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• 2021

Purpose - The purpose of this paper is to investigate the relationship between earnings management and the disclosure effect of share repurchase. In addition, we analyze whether the relationship between earnings management and share repurchase is affected by executive stock options. Design/methodology/approach - We calculate the discretionary accrual amount for the year immediately preceding the share repurchase and the cumulative excess return around the announcement of the share repurchase, and examine the relationship between the two by regression analysis. Findings - We confirmed a negative relationship between discretionary accrual in the year immediately preceding the share repurchase and the market response to the share repurchase disclosure. In particular, it was found that the negative relationship between discretionary accrual and stock price return on share repurchase announcement was found to decrease in companies to which executive stock options were granted. Research implications or Originality - When uncertainties exist in the motives for share repurchase, we find that earnings management and executive stock options can be useful tools for reducing the adverse selection risk inherent in share repurchase announcements.

• KIEAE Journal
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• v.10 no.2
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• pp.63-69
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• 2010

Diverse problems in wind environment has occurred through rapid urbanization and growth of high-rise building numbers, This study aims to propose the CFD (Computational Fluid Dynamics) simulation method and evaluation standard of wind environment in site planning of high rise apartment housing. The CFD simulation method proposed in this study is not existing detail simulation, but it is the method that a designer can correct and develop the design through immediate evaluation of design options in concept design phase. Therefore, the proposed CFD simulation method of wind environment in this study uses the BIM based CFD tool in which the 3D model in concept design phase can be used as for the CFD simulation. In this paper, the study examines existing evaluation standards of comfortableness level in wind environment for pedestrian near buildings, and selects new evaluation method which is possible to apply to the proposed CFD simulation method. In addition, it is to examine calculation time-spending and appropriate mesh division method for finding CFD result which is useful to find the best design options in aspect of wind environment in concept design phase. Furthermore, it proposes the wind environment evaluation method through BIM based CFD simulation.

• Journal of Magnetics
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• v.20 no.2
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• pp.176-185
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• 2015

We present the design optimization of the magnetic pole and slot design options that minimize the cogging torque of permanent-magnet (PM) brushless generators for small wind turbine generators. Most small wind-turbines use direct-driven PM generators which have the characteristics of low speed and high efficiency. Small wind-turbines are usually self-starting and require very simple controls. The cogging torque is an inherent characteristic of PM generators, and is mainly caused by the generator's geometry. The inherent the cogging torque can cause problems during turbine start-up and cut-in in order to start softly and to run a power generator even when there is little wind power during turbine start-up. Thus, to improve the operation of small turbines, it is important to minimize the cogging torque. To determine the effects of the cogging torque reductions, we adjust the slot opening width, slot skewing, mounting method of magnets, magnet shape, and the opening and combinations of different numbers of slots per pole. Of these different methods, we combine the methods and optimized the design variables for the most significant design options affecting the cogging torque. Finally, we apply to the target design model and compare FEA simulation and measured results to validate the design optimization.

• Nuclear Engineering and Technology
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• v.38 no.2
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• pp.109-118
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• 2006

Various indirect power cycle options for a helium cooled gas cooled fast reactor (GFR) with particular focus on a supercritical $CO_2(SCO_2)$ indirect cycle are investigated as an alternative to a helium cooled direct cycle GFR. The balance of plant (BOP) options include helium-nitrogen Brayton cycle, supercritical water Rankine cycle, and $SCO_2$ recompression Brayton power cycle in three versions: (1) basic design with turbine inlet temperature of $550^{\circ}C$, (2) advanced design with turbine inlet temperature of $650^{\circ}C$ and (3) advanced design with the same turbine inlet temperature and reduced compressor inlet temperature. The indirect $SCO_2$ recompression cycle is found attractive since in addition to easier BOP maintenance it allows significant reduction of core outlet temperature, making design of the primary system easier while achieving very attractive efficiencies comparable to or slightly lower than, the efficiency of the reference GFR direct cycle design. In addition, the indirect cycle arrangement allows significant reduction of the GFR &proximate-containment& and the BOP for the $SCO_2$ cycle is very compact. Both these factors will lead to reduced capital cost.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.953-968
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• 2009

It is important to accurately predict the temperature and density distributions in large stratified enclosures both for design optimization and accident analysis. Current reactor system analysis codes only provide lumped-volume based models that can give very approximate results. Previous scaling analysis has shown that stratified mixing processes in large stably stratified enclosures can be described using one-dimensional differential equations, with the vertical transport by jets modeled using integral techniques. This allows very large reductions in computational effort compared to three-dimensional CFD simulation. The BMIX++ (Berkeley mechanistic MIXing code in C++) code was developed to implement such ideas. This paper summarizes major models for the BMIX++ code, presents the two-plume mixing experiment simulation as one validation example, and describes the codes' application to the liquid salt buffer pool system in the AHTR (Advanced High Temperature Reactor) design. Three design options have been simulated and they exhibit significantly different stratification patterns. One of design options shows the mildest thermal stratification and is identified as the best design option. This application shows that the BMIX++ code has capability to provide the reactor designers with insights to understand complex mixing behavior with mechanistic methods. Similar analysis is possible for liquid-metal cooled reactors.