• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.269-282
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• 2014

The objective of this study is to find out whether the developed semi-empirical biofilm model can be applicable to real BAF pilot-scale wastewater treatment. In addition, the optimum operating conditions of BAF as a function of process variables such as organic loading change can be drawn based on the simulation results of model. The results will provide the economic and efficient BAF process design and operating control. As a result, developed semi-empirical biofilm model which is relatively simple compared to mathematical model can simulate three BAF processes consisted of 25 layers within 1 seconds. When this model was used for simulating real pilot scale BAF process and the simulated water quality values were compared to experimental ones, simulated TCOD, SCOD, TN, $NH_4{^+}$-N, $NO_x{^-}$-N, alkalinity values were different to experimental ones within 21%, 20%, 8.1%, 48%, 10%, and 23%, respectively. Therefore, if the BAF system was equipped with automatic control, the BAF process can be better efficiently adapted under the condition of significant change of influent loading.

• The Journal of Information Technology
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• v.5 no.2
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• pp.81-94
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• 2002

When a alarm is happened in nuclear power plant, operator tries to identify the direct and specific causes of the alarm and to do proper actions to mitigate the effect of it. To recognize the specific causes of it, the operator uses his experiences, alarm procedures, logic diagrams and so on. But, if the alarm procedure described many causes of the alarm unfortunately, it is very difficult for the operator who has no experience on the alarm to search the causes of it in hundreds of logic diagrams when emergency. In this study, a system is proposed, which tracks and displays the causes of alarms on-line from computerized logic diagrams.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.101-113
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• 2008

VMS are installed in many Korean highways in oder to give drivers informations such as travel time to destination, congestion and Incident situation. However, some guidelines for install VMS are restricted in only geometric factors although human factors considering driver behavior are very important to affect the VMS installation. Therefore, this paper are focusing on developing and verifying the discriminant model for VMS installation considering human factors. As a result, following outputs are obtained ; (1) developing the discriminant model using human factors of driving simulation experiments in oder to predict driver reading VMS messages safely detour highway. (2) proving that driving experiences in highway, personal driving history, vehicle speed orderly affects VMS installation (3) verifying predictability of developed model by comparing the real values with predicted values. (4) suggesting that VMS should be installed off 3.2Km from the I.C. of rural highway.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.971-979
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• 2023

Small ships (<499 GT) constitute 46% of the existing ships, therefore, it can be concluded that they produce relatively high CO₂ gas emissions. Operating in optimal trim conditions can reduce the resistance of the ship, which results in fewer greenhouse gases. An affordable way for trim optimization is to adjust the weight distribution to obtain an optimum longitudinal center of gravity (LCG). Therefore, in this study, the effect of LCG changes on the resistance of a small planing ship is studied using empirical and numerical analyses. The Savitsky method employing Maxsurf resistance and the STAR-CCM+ commercial computational fluid dynamics (CFD) software is used for the empirical and numerical analyses, respectively. Finally, the total resistance from the ship design process is compared to obtain the optimum LCG. To summarize, using numerical analysis, optimum LCG is achieved at the 46.2% length overall (LoA) at Froude Number 0.56, and 43.4% LoA at Froude Number 0.63, which provides a significant resistance reduction of 41.12 - 45.16% compared to the reference point at 29.2% LoA.

• Journal of Digital Convergence
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• v.11 no.3
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• pp.327-335
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• 2013

Purpose: The purpose of this study was to identify the factors related in an urban resident's drinking state and drinking problem. Methods: The data was collected from Oct. 2008 to Sep. 2009. Data were collected by questionaire from 359 urban resident over 20 years old and drinking experience residing. The instruments for this study were the alcohol use disorder identification test(AUDIT), the related factors of alcohol drinking. The data were analyzed using descriptive statistics, t-test, ANOVA, hierarchical multiple regression with the SPSS 18.0 program. Results: The problem drinking were 35.7% on AUDIT. (a) Male had significant effect on drinking problem; (b) If you drank alcohol for the first time prior to high school graduation had significant effect on drinking problem; (c) Permanent rental or unlicensed residential had significant effect on drinking problem; (d) Experience in drunk driving had significant effect on drinking problem. Conclusion: It is nessary to education at early childhood for the prevention of drinking problems and regular management for high risk.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.289-296
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• 2015

This convergence study was conducted to compare difference of risk behaviors and injury incidence between younger(under 65 years) and elderly(over 65 years). For this analysis we used law data of nation-wide community health survey data during August to October 2010. Data of drink-driving, seat belt use, injury incidence rate, type of injury, cause of injury were used for comparison. Seat belt use(85.16% vs 78.81%) was high but drink-driving(12.99% vs 13.24%) was low in elderly. Injury incidence was high especially in falls(1.07% vs 2.22%). In conclusion, elderly do less risk behaviors, but experienced much more injuries especially falls.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.735-745
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• 2023

The purpose of this study is to examine how the control of an agent according to a driver's social status affects user experience factors in a multi-user environment of self-driving vehicles. We conducted a user study where participants viewed four scenarios (route changing/parking x accepting/declining a fellow passenger's command) and answered a survey, followed by a post-hoc interview. Results showed that either the routing scenario or accepting a passenger's command scenario had higher usefulness (convenience, effectiveness, efficiency) than their counterparts. Regardless of the car owner's social status, participants rated AI agents more positively when they met their goals effectively. They also stressed that vehicle owners should always be in control of their agents. This study can provide guidelines for designing future autonomous driving scenarios where an agent interacts with a driver, and passengers.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.6
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• pp.642-648
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• 2015

Recently, there have been many studies pertaining to reducing energy consumption on ships. As part of those studies, the energy consumption of ships can be reduced by understanding and controlling the varying loads, excluding fixed loads. In existing ships, engine room fans are usually operated based on the actual experience of the crew without any special guidelines. To realize energy reduction, we investigate the characteristics of engine-room fans, and we propose an energy-management system called the engine room fan control system (ERFCS) and the ERFCS algorithm. The ERFCS controls the fan speed depending on the temperature and pressure, where one to four fans are operated depending on changes in the load. In addition, the minimum rotation speed of the engine-room fan was limited to 50% to prevent the surging phenomenon, which is due to fan damage or low pressure resulting from mechanical friction or heating at low fan speeds. We develop a fan control system simulation model using LabVIEW that is based on the proposed algorithm and ISO 8861. Finally, we perform simulations to confirm that operation of the proposed fan control system is possible using only 46.4% of the power required by the existing method.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.223-232
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• 2015

This study has analyzed the factors that influence the safety consciousness of elderly drivers. To achieve this, 307 elderly who drives commercial and non-commercial in Daejeon, Sejong, Chungnam and Chungbuk area were selected as study subjects. For the data analysis, PASW Statistics 18.0 was used. The main results of this study are as follows. The level of safety consciousness of commercial and non-commercial drivers were 6.49 and 6.93 respectively showing that drivers of non-commercial were significantly higher. Second, the factors that influence the safety consciousness were shown to be significantly different for each group. The factors that influence the safety consciousness of commercial drivers were shown in the order of safety-seeking motivation, economic status, daily driving hours, sensation-seeking disposition. The factors that influence the safety consciousness of non-commercial drivers were shown in the order of safety-seeking motivation, health status, whether or not the accident was experienced, sensation-seeking disposition. Based on these results, several ways were suggested to improve the safety consciousness of elderly drivers and prevent the traffic accidents.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.81-100
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• 2018

This study investigated the influential factor over the intention to buy autonomous driving car by applying extended technology acceptance model (TAM2). To this end, 117 ordinary persons experienced in driving car were analyzed by using SEM(Structural Equation Modeling). Analysis shows that the perceived usefulness and purchase intention is positively affected by social influence and recognized risk. It is found that perceived usefulness is not affected, but purchase intention is positively affected in the case of innovation. On the contrary, analysis shows that driving capability and car playfulness recognized by individual have no influence on the perceived easiness. Although the result that driving capability recognized by individual negatively affects perceived usefulness was not included in the study hypothesis, it was remarkable. Generalizing the above result, it is found that social influence, innovation and recognized risk as variables which affect the intention to buy autonomous car play the role of significant variable. This study is meaningful in that such result can foresee the perception of preliminary accommodators of new technology of the 4th industrial revolution, autonomous driving car.