• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.72-78
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• 2019

Inlet hammershock is the critical loads condition for designing the inlet duct structure of a fighter. The sudden flow reduction in engine compressor causes inlet hammershock with high pressure. The traditional method was used to combine extreme conditions (maximum speed, sea level altitude, and cold day) to analyze this compression wave inlet hammershock pressure. However, after the 90s there have been papers that presented the probabilistic approach for the inlet hammershock to achieve the appropriate design pressure. This study shows how to analyze the inlet hammershock pressure by making practical use of the Republic of Korea Air Force real flight usage data under probabilistic approach and then analyze approximately 30% decreased inlet hammershock pressure compared with the traditional valve.

• Journal of Radiation Protection and Research
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• v.38 no.2
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• pp.60-67
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• 2013

A diffusion coefficient is an important parameter in the prediction of atmospheric dispersion using a Gaussian plume model, and its modelling approach varies. In this study, dispersion coefficients recommended by the U. S. Nuclear Regulatory Commission's (U. S. NRC's) regulatory guide and the Canadian Nuclear Safety Commission's (CNSC's) regulatory guide, and used in probabilistic accident consequence analysis codes MACCS and MACCS2 have been investigated. Based on the atmospheric dispersion model for a hypothetical accidental release recommended by the U. S. NRC, its influence to atmospheric dispersion factor was discussed. It was found that diffusion coefficients are basically predicted from a Pasquill- Gifford curve, but various curve fitting equations are recommended or used. A lateral dispersion coefficient is corrected with consideration for the additional spread due to plume meandering in all models, however its modelling approach showed a distinctive difference. Moreover, a vertical dispersion coefficient is corrected with consideration for the additional plume spread due to surface roughness in all models, except for the U. S. NRC's recommendation. For a specified surface roughness, the atmospheric dispersion factors showed differences up to approximately 4 times depending on the modelling approach of a dispersion coefficient. For the same model, the atmospheric dispersion factors showed differences by 2 to 3 times depending on surface roughness.

• Journal of Information Technology and Architecture
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• v.9 no.3
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• pp.253-263
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• 2012

Presented in the paper is a methodology for the distributed simulation of underwater warfare based on standard synthetic environment. In the case of underwater warfare simulation, it is very important to reflect environmental data, such as salinity and temperature. For the reusability and interoperability of environmental data, this paper adopts Synthetic Environmental Data Representation and Interchange Specification (SEDRIS(ISO standard for environmental data)). Although SEDRIS provides various merits as an international standard, applying of SEDRIS has been hindered by its broadness and heaviness. To relieve the difficulties, this paper proposes an efficient procedure to utilize SEDRIS technology for the atmosphere and underwater environment. This paper identifies SEDRIS structure for the atmosphere/underwater structured dimensional grid-based and implements the proposed procedure on the High Level Architecture (HLA) / Run-Time Infrastructure (RTI) to explain the generation of the battlefield in a distributed simulation system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.2
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• pp.133-141
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• 2021

The probe vehicle penetration rate is a required parameter in the estimation of entire volume, density, and queue length from probe vehicle data. The previous studies have proposed estimation methods without point detectors, which are based on probability structures for the locations of probe and non-probe vehicles; however, such methods are poorly suited to the case of multi-lane streets. Therefore, this study aimed to estimate the probe vehicle penetration rate at a multi-lane intersection and introduce a probability distribution of the queue length of each lane. Although a gap between estimates and observations was found, the estimates followed the trend of observations; the estimation could be improved by the correction factor hereafter. This study is expected to be used as a basic study for the estimation of entire volume, density, and queue length at multi-lane intersections without point detectors.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.519-526
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• 2019

This study proposes a methodology for estimating the appropriate capacity of anchorage for ports requiring the establishment of waiting anchorage and then applying the methodology to the ports in Jinhae Bay to compare it with the anchorage capacity of major ports in Korea. To estimate the appropriate anchorage capacity, the "Anchorage Capacity Index" was used, which was calculated from the "Total Gross Tonnage" and "Simultaneous Anchoring Capacity". The calculations were made according to the anchorage capacity index of 0.89 of the target harbors. The adequate anchorage capacity index for the new waiting anchorage was analyzed at a level of 6.0. If the concept of anchorage capacity index suggested in this study is reflected as a new design criteria of waiting anchorage, it will be helpful for the safety of berth, safety of anchorage and effective operation of harbor.

• Journal of the Korean Geographical Society
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• v.37 no.5
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• pp.480-497
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• 2002

This paper is concerned with unveiling the responsiveness of large Korean firms to external shock by examining corporate restructuring in terms of production and organization. Throughout empirical research, I speculate on how corporate restructuring influences and relates to corporate teaming and adaptation. The main findings of this research are as follows. First, the restructuring of business structure was expected to strengthen core competencies and improve profitability and the restructuring of organizational structure to make it possible for responding more quickly to radical changes in its business environment. Second, both downsizing and employment adjustment have assisted the firm with unlearning obsolete practices, preconditions necessary for effectively accomplishing new teaming practices. Third, both the spatial reorganization of production activities and process innovation require and involve learning processes. In conclusion, it claims that corporate restructuring can be seen as a powerful loaming tool, particularly in the context of radical economic change.

• Journal of Korea Technology Innovation Society
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• v.12 no.2
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• pp.335-359
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• 2009

This study explores the IT governance structures of the Korean conglomerates. It investigates IT organization structures, decision making frameworks and processes, communication channels, implementation mechanisms, and performance evaluation methods around IT activities of the Korean conglomerates by analyzing four different cases. The results show that all of the conglomerates have an IT service firms as one of their subsidiaries, and all the subsidiaries in the conglomerates outsource their IT divisions to the IT service firms, The client firms in the conglomerates operate IT strategy and planning teams to coordinate their IT activities with their outsourcing partners. The IT governance archetype of the Korean conglomerates is found to be "business monarchy" because the client firms mostly make IT decisions. However, the IT service firms provide the information of IT trends and solutions to their clients, so the IT governance archetype of input framework for IT decisions can be "IT monarchy". In addition, the conglomerate which has the more centralized IT governance architecture appears to prefer the more integrated implementation mechanisms for IT decisions. The results of this study are expected to be used as a benchmarking model for the organizations which try to develop an effective IT governance structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.490-499
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• 2017

In recent years, the introduction of complex systems analysis based on various variables has become more active in order to identify and analyze complex problems of Modern Society. Prediction of patients' spatial perception and usability according to the spatial arrangement of the outpatient department is a very important factor for providing high quality hospital service. For objective analysis, the standard program procedure and analysis index for the diseases of the elderly were prepared and the uniformity of the atmospheric space was evaluated through heat map analysis and quantitative analysis. In this study, 73 cells were installed and simulated to analyze the uniformity of the four alternatives according to the change of the arrangement of the medical care space, receiving space, and consultation space using the complex system analysis method for the nursing hospitals. The resulting density was derived. The results are as follows. 1)The layout of the reception space has the greatest influence on the total spatial density of the waiting space. 2) The uniformity of the waiting space can be increased by separating the examination space and the examination space. 3)The closer the location of the receiving space is from the entrance, the greater the density of the waiting space. Finally, this study applied discrete event simulation to the evaluation of uniformity of atmosphere space, and proved that the actor - based model can be utilized for utilization and evaluation as spatial analysis methodology.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.93-108
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• 2019

Recently, air pollution from the marine ports has become a serious issue all over the world. Because marine trade accounts for 99.7% of Korea's trade, efforts are required to recognize the level of port pollution and establish environmental policies. This study estimates air pollution emitted during the berthing process in the Gwangyang and Ulsan ports. Data on ship activity and characteristics are collected and reasonable methodologies and factors from EEA and EPA are adopted. The results show that 253.09 tons of CO, 1986.61 tons of NOx, 684.01 tons of SOx, 47.88 tons of $PM_{10}$, and 44.69 tons of $PM_{2.5}$ are emitted at the Gwangyang port. Further, the Ulsan port emitted 212.28 tons of CO, 1712.54 tons of NOx, 573.72 tons of SOx, 40.16 tons of $PM_{10}$, and 37.48 tons of $PM_{2.5}$. A stage-by-stage plan for installing AMP infrastructure is suggested as part of a green port policy. This research provides the current pollution status and contributes guidelines for the direction of future policy.

• Journal of Preventive Medicine and Public Health
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• v.32 no.2
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• pp.177-182
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• 1999

Objectives: To reexamine the association between air pollution and daily mortality in Seoul, Korea using a method of meta-analysis with the data filed for 1991 through 1995. Methods: A separate Poisson regression analysis on each district within the metropolitan area of Seoul was conducted to regress daily death counts on levels of each ambient air pollutant, such as total suspended particulates (TSP), sulfur dioxide $(SO_2)$, and ozone $(O_3)$, controlling for variability in the weather condition. We calculated a weighted mean as a meta-analysis summary of the estimates and its standard error. Results: We found that the p value from each pollutant model to test the homogeneity assumption was small (p<0.01) because of the large disparity among district-specific estimates. Therefore, all results reported here were estimated from the random effect model. Using the weighted mean that we calculated, the mortality at a $100{\mu}g/m^3$ increment in a 3-day moving average of TSP levels was 1.034 (95% Cl 1.009-1.059). The mortality was estimated to increase 6% (95% Cl 3-10%) and 3% (95% Cl 0-6%) with each 50 ppb increase for 9-day moving average of SO2 and 1-hr maximum O3, respectively. Conclusions: Like most of air pollution epidemiologic studies, this meta-analysis cannot avoid fleeing from measurement misclassification since no personal measurement was taken. However, we can expect that a measurement bias be reduced in a district-specific estimate since a monitoring station is hefter representative cf air quality of the matched district. The similar results to those from the previous studios indicated existence of health effect of air pollution at current levels in many industrialized countries, including Korea.