• The KSFM Journal of Fluid Machinery
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• v.19 no.1
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• pp.18-23
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• 2016

A HVAC(Heating Ventilation and Air Conditioning) is adapted to increase the comfort of the cabin environment for train. The train HVAC duct system has very long duct and many outlets due to the shape of a train set. the duct cross section shape is limited by a roof structure and equipments. Therefore, the pressure distribution and flow uniformity is an important performance indicator for the duct system. In this study, the existing blow down type HVAC duct system for a train was supplemented to improve the flow uniformity by applying a design method combining design of experiment (DOE) with numerical analysis. The design variables and the test sets were selected and the performance for each test set was evaluated using CFD(Computational Fluid Dynamics). The influence of each design variable on the system performance was analysed based on the results of the performance evaluation on the test sets. Furthermore, the optimized model, whose the flow uniformity was improved was produced using the direct optimization(gradient-based method). Finally, the performance of the optimized model was evaluated using numerical analysis, and it was confirmed that its flow uniformity has indeed improved.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.107-113
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• 2021

Plant Configuration Management(CM) is an activity to maintain consistency of design requirements, physical configuration, facility configuration information throughout the life cycle of the plant by systematically managing changes that occur during the plant design and operation process. Conformity between information must be ensured not only in the design stage, but also in the case of design changes in the operation and maintenance stages, and thus a computer system capable of efficiently managing them is required. In particular, in consideration of an application to small and medium-sized domestic plants, a computer system that can support configuration management at a low cost is needed. Accordingly, in this study, a configuration management system has been developed to support the management of plant design information and change procedures in the operation stage of small and medium-sized plants. Here, a case for quantitatively evaluating the effectiveness of the developed system is described.

• KIEAE Journal
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• v.12 no.1
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• pp.3-10
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• 2012

Recently, the increase of impervious area has been pointed out as a major cause of climate change and biotop area deterioration]. Therefore, quantitative indicators for environmental housing design and planning have been needed especially to control the impervious area. The Biotop Area Ratio(BAR) as the mostly applied environmental planning control instrument in Korea verifying the possibility of utilizing has been used effectively in various aspects. However, the fact that the space types are based on two dimension and ecological functions of spaces are simplified has shown the limitations of this planning instrument in the use as planning and evaluation indicator. In this study, classification criteria and the weighting of the space types in similar indicators Biotopflaechenfaktor (BFF, Berlin), Seattle Green Factor (SGF, Seattle), and Green Area Factor (GAF, Malmo) were analyzed. These indicators are similar in the sense that they apply weights to calculate the area and express a percentage of land area. The findings are as follows: The basic method that can estimate the vegetation volume is proposed to overcome the limitation of the BAR. It also was proven that the introduction of three-dimensional volume rate of biotops area was possible. Finally, the framework of space type classification criteria is proposed through linkages with relevant laws and regulations. With the improvement of the space types, the BAR is expected to be reasonable indicator in outdoor space evaluation in housing project.

• Wind and Structures
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• v.16 no.6
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• pp.579-601
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• 2013

Interference effects are of considerable concern for group hyperboloidal cooling towers, but evaluation methods and results are different from each other because of the insufficient understanding on the structure behavior. Therefore, the mechanical performance of hyperboloidal cooling tower shell under wind loads was illustrated according to some basic properties drawn from horizontal rings and cantilever beams. The hyperboloidal cooling tower shell can be regarded as the coupling of horizontal rings and meridian cantilever beams, and this perception is beneficial for understanding the mechanical performance under wind loads. Afterwards, the mean external latitude wind pressure distribution, CP(${\theta}$), was artificially adjusted to pursue the relationship between different CP(${\theta}$) and wind-induced responses. It was found that the maximum responses in hyperboloidal cooling tower shell are primarily dominated by the non-uniformity of CP(${\theta}$) but not the local pressure amplitude CP or overall resistance/drag coefficient CD. In all the internal forces, the maximum amplitude of meridian axial tension shows remarkable sensitivity to the variation of CP(${\theta}$) and it's also the controlling force in structure design, so it was selected as an indicator to evaluate the influence of CP(${\theta}$) on responses. Based on its sensitivity to different adjustment parameters of CP(${\theta}$), an comprehensive response influence factor, RIF, was deduced to assess the meridian axial tension for arbitrary CP(${\theta}$).

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.4
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• pp.161-170
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• 2014

Newmark-type deformation analysis has rarely been done in Korea due to the popularity of simple pseudo-static limit equilibrium analysis and detailed time-history FE/FD dynamic analysis. However, the Korean seismic dam design code updated in 2011 prescribes Newmark-type deformation analysis as a major dynamic analysis method for the seismic evaluation of fill dams. In addition, a design PGA for dynamic analysis is significantly increased in the code. This paper aims to study the seismic evaluation of four existing large fill dams through advanced FEM/Newmark-type deformation analyses for the artificial earthquake time histories with the design PGA of 0.22g. Dynamic soil properties obtained from in-situ geo-physical surveys are applied as input parameters. For the FEM/Newmark analyses, sensitivity analyses are performed to study the effects of input PGA and $G_{max}$ of shell zone on the Newmark deformation. As a result, in terms of deformation, four fill dams are proved to be reasonably safe under the PGA of 0.22g with yield coefficients of 0.136 to 0.187, which are highly resistant for extreme events. Sensitivity analysis as a function of PGA shows that $PGA_{30cm}$ (a limiting PGA to cause the 30 cm of Newmark permanent displacement on the critical slip surface) is a good indicator for seismic safety check. CFRD shows a higher seismic resistance than ECRD. Another sensitivity analysis shows that $G_{max}$ per depth does not significantly affect the site response characteristics, however lower $G_{max}$ profile causes larger Newmark deformation. Through this study, it is proved that the amplification of ground motion within the sliding mass and the location of critical slip surface are the dominant factors governing permanent displacements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.8021-8029
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• 2015

This study obtains design assessment indexes that should be considered in order to improvements of the public space was to analysis the importance in the public officials/academics and practitioners side. Obtained assessment topics in accordance with characteristic of public space through previous research to them and after a detailed selection indicators was so lead through the FGI. Derived surface was subjected to the significance analysis AHP through the survey expert. For this study, the importance of the public space are working professionals usability, publicness, environment, connectivity, identity, spatiality the order, public officials/academics usability, environment, connectivity, identity, spatiality, publicness the order. In addition, professionals working in the comprehensive analysis of the most important priority was to recognize safety, public officials/academics of the most important element appeared to have cleanliness. The results obtained in this study will be used as an index that can be used in planning and evaluation for consideration of the next improvement of public space.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.5
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• pp.508-515
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• 2019

Although various quantitative indexes are used as criteria for deciding the success of software R & D projects, it is somewhat difficult to find which quantitative indexes are appropriate. In this paper, we propose a quantitative evaluation index generation process for software product development using ISO / IEC25023, which is used as a standard of software quality level, to provide criteria for quantitative evaluation index of software development. The proposed process consists of two stages. In the first step, quality characteristics and subcharacteristics of ISO / IEC25023 standard specification are derived and in the second stage, we derive an evaluation indicator guides that matches the quality characteristics and sub characteristics. The proposed quantitative evaluation index generation process is expected to be helpful for the selection of quantitative evaluation indexes according to the characteristics of software development projects.

• Journal of Information Technology Services
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• v.22 no.2
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• pp.71-92
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• 2023

Globally, under the leadership of advanced ICT countries, the private sector is promoting various policies to promote the digital transformation of public services. Looking at the research trend, design of public service indicators, development of evaluation system, and empirical research are being carried out steadily, but there are insufficient research cases on models in which the private sector participates in the planning, development, and operation of public services. In this study, Private-centric digital public service suitability evaluation indicators were discovered through interviews with experts in various fields, and weights for each indicator were analyzed through AHP evaluation. In addition, by applying the analysis results to 18 digital public services on a trial basis, the importance and priority of evaluation indicators for each service were derived, and at the same time, the evaluation framework was designed and applied to diagnose implications. As a result of the study, 'social utility', 'corporate acceptability', and 'public acceptability' were selected as the top three indicators of suitability evaluation. At this time, it was analyzed that the weight of the 'company acceptability' index, which includes sub-indices such as 'service profitability', 'service scalability', and 'private initiative possibility', was the highest among the three top indicators. As a result of the demonstration for public services, "IoT facility unmanned remote monitoring service", "blockchain real estate transaction service", and "digital twin disaster prediction service" were evaluated as the most suitable public services for the transition to the private sector.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.723-731
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• 2016

A core technological base to provide enhanced data rates required by 5G mobile wireless communications is the improved bandwidth efficiency using massive multiple-input multiple-output (MIMO) transmission. MIMO transmission requires the channel estimation using the channel state information reference signaling (CSI-RS) and appropriate beamforming, thus the design of the codebook defining proper beamforming vectors is an important issue. In this paper, we propose a multi-rank codebook based on the discrete Fourier transform (DFT) matrix, by utilizing statistical properties of the channel generated by the spatial channel model (SCM). The proposed method includes a structural change of the precoding matrix indicator (PMI) by considering the phase difference distributions between adjacent antenna elements, as well as the selected codevector characteristics of each transmission layer. Performance gain of the proposed method is evaluated and verified by making the performance comparison to the 3GPP standard codebooks adopted by Long-Term Evolution (LTE) systems.

• The Journal of Korean Society for School & Community Health Education
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• v.6
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• pp.35-48
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• 2005

The age of the very first smoking is a significant indicator of life-long health status. Smoking prevention intervention was actively conducted based in middle and high schools with the support of the Korean Act for Health Promotion since 1998. These governmental supports became large and various smoking prevention programs were developed and conducted in diverse standards and perspectives. This study made a comprehensive descriptive literature review on smoking prevention educational programs for youth in Korea to identify the intervention quality and effectiveness of them for future smoking prevention program development. A total of 28 peer-reviewed journal articles published between May, 1995 and May 2005 (for the last 10 years) were finally included in this review process. The study participants should be adolescences in middle or high schools in Korea and the intervention types of the review studies should be smoking prevention or cessation educational programs. The outcomes of the reviewed studies were reanalyzed by the participants' characteristics, theory basement, evaluation design, intervention period, evaluation outcomes, and program effectiveness Most smoking intervention programs were not specified by sex and smoking status. Largely most intervention programs focused on male students although female students' smoking percent is increasing including both smokers and nonsmokers. Based on the school grades, the large percents of smoking intervention were conducted to the first grade of middle school and the first grade of high school. Almost 70% of the reviewed studies did not apply any health behavior change theories and the Transtheoretical model and social cognitive theory were utilized in 7 studies among the last reviewed 30%. The theory-based intervention studies had greater effectiveness than the non-theory based studies. More than 90% had quasi-experimental evaluation design and the effectiveness of the non-experimental designed study seemed over estimated than the quasi-experimental or experimental designed studies. More than 60% of the reviewed studies made their education for less than j days, over a short period and the evaluation factors were knowledge and attitude in general which can be obtained in short intervention period. Therefore, smoking intervention programs for youth in Korea need to be modified in terms of research design such as the intervention period, intervention-evaluation design, theory-based approach, and population-focused intervention specification.