• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.984-990
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• 2017

Mesh screen modeling and liquid propellant discharge simulation of surface tension tank were performed using commercial CFD software Flow-3d. $350{\times}2600$, $400{\times}3000$ and $510{\times}3600$ DTW mesh screen were modeled using macroscopic porous media model. Porosity, capillary pressure, and drag coefficient were assigned for each mesh screen model, and bubble point simulations were performed. The mesh screen model was validated with the experimental data. Based on the screen modeling, liquid propellant discharge simulation from PMD tank was performed. NTO was assigned as the liquid propellant, and void was set to flow into the tank inlet to achieve an initial volume flow rate of liquid propellant in $3{\times}10^{-3}g$ acceleration condition. The intial flow pressure drop through the mesh screen was approximately 270 Pa, and the pressure drop increased with time. Liquid propellant discharge was sustained until the flow pressure drop reached approximately 630 Pa, which was near the estimated bubble point value of the screen model.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.94-103
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• 2015

This study analyzes the influence factors on elderly pedestrian accident. Elderly people are easy to be badly injured by car accidents compared to younger people. Therefore, various plans and measures are required to protect elderly pedestrian from accidents. However, pedestrian accidents studies only focused on microscopic factors such as attribute of driver, pedestrian, road design. In order to prevent pedestrian accident and reduce the severity of the accident, not only microscopic factors but macroscopic variables such as urban planning and facility should be considered. In this regard, this study develops an ordered probit model introduced the characteristics of urban facility which were not considered in the previous studies. The result shows that there is higher level of accident severity in such areas as large commercial area, well-developed area with transportation infrastructure service and non-pedestrian safety zone. Thus, various and appropriate countermeasures should be prepared in order that pedestrian accident can be prevented in the areas mentioned above. In addition to the aforementioned variables, it is revealed that other variables including vehicle speed, gender and age of pedestrian, weather condition, type of vehicle, etc. partly affect the severity of pedestrian accident.

• Journal of Korean Society of Transportation
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• v.18 no.2
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• pp.7-16
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• 2000

This study Presents an guideline of the exclusive bus and/or truck lane on 8 lanes freeways using FREFLO model and INTEGRATiON model. Four alternatives : do nothing, bus exclusive lane, truck exclusive lane, bus and truck exclusive lane, were evaluated using average daily vehicle travel time as measures of effectiveness. It is found that bus and truck exclusive lane is the most effective alternative reducing total travel time by 7% when ADT is below 80,000 vehicle/day. However, when ADT is above 80,000 vehicle/day and bus Proportion is above 12%, bus exclusive lane is the most effective alternative reducing total travel time by more than 5.6%. It is further found that INTEGRATION, the stochastic and microscopic model, is more sensitive than FREFLO, the deterministic and macroscopic model, in evaluating the effectiveness of four alternatives.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.4
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• pp.218-228
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• 2023

Maintaining sea superiority through successful mission accomplishments of warships is being proved to be an important factor of winning a war, as in the Ukraine-Russia war. in order to ensure the ability of a warship to perform its duties, the survivability of the warship must be strengthened. In particular, among the survivability factors, vulnerability is closely related to a damage assessment, and these vulnerability data are used as basic data to measure the mission capability. The warship's mission capability is usually measured using a wargame model, but only the operational effects of a macroscopic view are measured with a theater level resolution. In order to analyze the effectiveness and efficiency of a weapon system in the context of advanced weapon systems and equipments, a warship's mission capability must be measured at the engagement level resolution. To this end, not the relationship between the displacement tonnage and the weight of warheads applied in the theater level model, but an engagement level resolution vulnerability assessment method that can specify physical and functional damage at the hit position should be applied. This study proposes a method of measuring a warship's mission capability by applying the warship vulnerability assessment method to the naval engagement level analysis model. The result can be used as basic data in developing engagement algorithms for effective and efficient operation tactics to be implemented from a single unit weapon system to multiple warships.

• Journal of Digital Convergence
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• v.14 no.5
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• pp.57-66
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• 2016

In this paper, we describe capstone-related courses in the Computer information department of Dongyang-Mirae University and propose a capstone design model for computer engineering discipline based on operating experiences during the last year. Class schedules and contents, etc are presented from the case studies of two courses on system analysis and design and graduation work(capstone design) opened in 2015. Towards the successful operation of capstone design targeted to training practical and talented professionals with creative problem-solving skills, we propose six execution steps along with principal activities and outputs: Course plan, Project plan, Development, Reporting, Evaluation of students and coursework, and Course feedback. The capstone design model of this study is characterized by presenting the necessity and importance of pre and post steps such as 'Course Plan' and 'Course reflux' from a macroscopic view and by applying software engineering techniques such as prototyping, configuration managements, etc to it.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.355-359
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• 2014

In this paper, we proposed the new fuzzy pattern classifier which combines several fuzzy models with simple consequent parts hierarchically. The basic component of the proposed fuzzy pattern classifier with hierarchical structure is a fuzzy model with simple consequent part so that the complexity of the proposed fuzzy pattern classifier is not high. In order to analyze and divide the input space, we use Fuzzy C-Means clustering algorithm. In addition, we exploit Conditional Fuzzy C-Means clustering algorithm to analyze the sub space which is divided by Fuzzy C-Means clustering algorithm. At each clustered region, we apply a fuzzy model with simple consequent part and build the fuzzy pattern classifier with hierarchical structure. Because of the hierarchical structure of the proposed pattern classifier, the data distribution of the input space can be analyzed in the macroscopic point of view and the microscopic point of view. Finally, in order to evaluate the classification ability of the proposed pattern classifier, the machine learning data sets are used.

• Health Policy and Management
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• v.28 no.2
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• pp.128-137
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• 2018

Background: This study aims to utilize Organization for Economic Cooperation and Development (OECD) data to identify macroscopic determinants of health at national level and to utilize it in health policy development through comparison and analysis with Korea. Methods: The potential years of life lost (PYLL) were used as dependent variables and 19 indicators were selected as health determinants to be independent variables based on the results of previous studies. Data analysis was done using SAS ver. 9.4 package (SAS Institute Inc., Cary, NC, USA) and model used in technical statistics concerning PYLL by countries, multi-linearity test between independent variables and OECD economic studies were modified and used. Results: From 1994 to 2012, the average PYLL for OECD countries was 4,262.9 years, the highest in Estonia and the lowest in Iceland. As a result of the analysis using the fixed effect model, the significant variables affecting PYLL were four variables: gross domestic product, nitric oxide, tobacco consumption, and number of doctors. The health determinants that had more influence on the PYLL of Korean people compared to other OECD countries were tobacco consumption, calorie consumption, fat intake and total health expenditure. Conclusion: In order to effectively reduce unnecessary deaths, we must continue to strengthen our smoking policy and nutrition policies such as calorie and fat intake. It is necessary to prevent the increase of total health expenditure due to the increase in the prevalence of chronic diseases and to strengthen the public health aspect.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.6
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• pp.339-348
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• 2006

Recently, many researches on detecting and responding worms due to the fatal infrastructural damages explosively damaged by automated attack tools, particularly worms. Network service vulnerability exploiting worms have high propagation velocity, exhaust network bandwidth and even disrupt the Internet. Previous worm researches focused on signature-based approaches however these days, approaches based on behavioral features of worms are more highlighted because of their low false positive rate and the attainability of early detection. In this paper, we propose a Distributed Worm Detection Model based on packet marking. The proposed model detects Worm Cycle and Infection Chain among which the behavior features of worms. Moreover, it supports high scalability and feasibility because of its distributed reacting mechanism and low processing overhead. We virtually implement worm propagation environment and evaluate the effectiveness of detecting and responding worm propagation.

• Journal of Korean Medicine Rehabilitation
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• v.30 no.3
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• pp.103-116
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• 2020

Objectives This study was designed to review the effect of herbal medicine on animal model with rheumatoid arthritis. Methods We reviewed studies published both in Korea and overseas, all published after 2008. We investigated 8 databases, 6 Korean databases and 2 of abroad. Searching was conducted through flowchart and 24 studies met our guideline. Datas were extrated and organized as animal model characteristics, experimental period, study design, herbal medicine used as intervention and rheumatoid arthritis indicator. Results 336 articles were primarily selected. After screening, 24 articles were left in the end. All 24 studies showed that the herbal medicine used in the animal experiment was effective on treating rheumatoid arthris, proven by macroscopic, histological, hematological and osteological indicators. Conclusions The result showed that herbal medicine is effective in treating rheumatoid arthritis through various pathways. However, study design and intervention were all different from each other and we could not specify the certain compound, material or substance of efficacy. Further study should be conducted to figure out the effectiveness of herbal medicine on rheumatoid arthritis.

• Journal of Korean Society for Atmospheric Environment
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• v.6 no.1
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• pp.85-96
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• 1990

Simultaneous removal efficiencies of hydrophilic and hydrophobic gaseous pollutants are experimentally determined, and the macroscopic removal mechanism of pollutants in a dry scrubber is analyzed using the extended model of three phase equilibrium distribution of pollutant at high temperatures that can describe the different morphological conditions of adsorbent and water at varying relative humidities. For the simplicity, the inside of spray dryer is divided into three regions of ; (1) absorption, (2) three-phase equilibrium, and (3) adsorption, and the removal efficiencies of each pollutants at three regions are observed at different experimental conditions to estimate the effects of important parameters of dry scrubber. The laboratory experiments simulate the three regions of spray dryer with the temperature control and thus evaporation rate of water from the slurry particle. $SO_2$ as a hydrophilic gaseous pollutant and vinyl chloride as a hydrophobic toxic gas are selected for the future field application to soid waste incineration, and the two types of slurry are made of the two sorbents ; 10 wt.% $Ca(OH)_2$, and 10 wt.% NaOH. Result of temperature effect shows the height of absorption plus three-phase region is decreased as the operation temperature is increased, which results in the lower removal efficiency of $SO_2$ but higher removal for vinyl chloride in the adsorption region of dry scrubber. The removal efficiency of $SO_2$ is higher by NaOH slurry than by $Ca(OH)_2$ slurry due to the hygroscopic nature of NaOH, while the removal of vinyl chloride is higher in $Ca(OH)_2$ case. From the analysis of redults using three-phase equilibrium distribution model, the effective two-phase partition coefficients can be obtained, and the possible extention in the application of the three-phase equilibrium model in a dry scrubber design has been demonstrated.