• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.627-637
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• 2020

Purpose: This experimental study was conducted to find out whether a water-mist fire suppression system can be applied to C.E.P., a representative combustible material of a rack storage. Method: First, it was confirmed whether the water-mist fire-extinguishing system used in this experiment was capable of extinguishing oil fires. After that, the C.E.P. boxes were loaded in the same small space as used in the oil fire experiment, and then the experiment was conducted on three scenarios; door opening, door closing, and door closing and increasing the internal load. The scenario was set considering the opening and space size conditions, which are important factors for the water-mist fire suppression. Result: Oil fire suppression tests have shown that fires are well extinguished in both the door open and closed conditions. In case of a fire of C.E.P. boxes in the same space condition as an oil fire, the fire was not extinguished in the door open condition. Fires were extinguished in the case with the door closed condition, but the afterglow was confirmed. Conclusion: In the oil fire suppression test, a water-mist fire suppression system extinguished a fire in both the door open and closed conditions. However, for the C.E.P fire, it was possible to extinguish only under the door closed condition, and there was a possibility of re-ignition.

• Journal of Korea Water Resources Association
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• v.56 no.spc1
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• pp.1059-1069
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• 2023

Dam-break flow occurs when an elevated dam suddenly collapses, resulting in the catastrophic release of rapid and uncontrolled impounded water. This study compares laminar and turbulent closure models for simulating three-dimensional dam-break flows using OpenFOAM. The Reynolds-Averaged Navier-Stokes (RANS) model, specifically the k-ε model, is employed to capture turbulent dissipation. Two scenarios are evaluated based on a laboratory experiment and a modified multi-layered block obstacle scenario. Both models effectively represent dam-break flows, with the turbulent closure model reducing oscillations. However, excessive dissipation in turbulent models can underestimate water surface profiles. Improving numerical schemes and grid resolution enhances flow recreation, particularly near structures and during turbulence. Model stability is more significantly influenced by numerical schemes and grid refinement than the use of turbulence closure. The k-ε model's reliance on time-averaging processes poses challenges in representing dam-break profiles with pronounced discontinuities and unsteadiness. While simulating turbulence models requires extensive computational efforts, the performance improvement compared to laminar models is marginal. To achieve better representation, more advanced turbulence models like Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) are recommended, necessitating small spatial and time scales. This research provides insights into the applicability of different modeling approaches for simulating dam-break flows, emphasizing the importance of accurate representation near structures and during turbulence.

• Information Systems Review
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• v.20 no.2
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• pp.1-19
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• 2018

In many countries, governments invest a substantial amount of budget in open government data (OGD) for governmental performance and transparency. To understand the actual performance of such policies, the governments should measure the realized value. Many organizations and researchers have attempted to assess the value of OGD. However, they have neglected a perspective of consumers who benefit from OGD. Moreover, little research has quantified the economic value. This research examines extant methods of intangible asset valuation to quantify the economic value of OGD in a citizen perspective. In consideration of the extant research methods and the characteristics of OGD, the contingent valuation method is the most appropriate because it effectively reflects various users and their purpose of use. We then conduct a survey of citizens living in Seoul, Korea and assess the economic value of OGD provided by the Seoul government. Findings show that citizens' willingness to pay (WTP) differs across respondents' prior experience, tax resistance, perceived benefit and perceived reality of virtual scenario, but it does not differ across their demographics. WTP also significantly varies across the question formats. We discuss the reliability of the results and implications for future research.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.2
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• pp.62-72
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• 2017

Spatio-temporal projection of evapotranspiration over croplands would be useful for assessment of climate change impact and development of adaptation strategies in agriculture. Potential evapotranspiration (PET) and dryness index (DI) during rice growing seasons were calculated using climate change scenario data provided by the National Institute of Meteorological Research (NIMR). A data processing tool for gridded climate data files, readGrADSWrapper, was used to calculate PET and DI during the current (1986-2005) and future (2006-2100) periods. Scripts were written to implement the formulas of PET and DI in R, which is an open source statistical data analysis tool. Evapotranspiration in rice fields ($PET_{Rice}$) was also determined using R scripts. The Spatio-temporal patterns of PET differed by regions in Korean Peninsula under current and future climate conditions. Overall, PET and $PET_{Rice}$ tended to increase throughout the $21^{st}$ century. Those results suggested that region-specific water resource managements would be needed to minimize the risk of water loss in the regions where considerable increases in PET would occur under the future climate conditions. For example, a number of provinces classified as a humid region were projected to become a sub-humid region in the future. The Spatio-temporal assessment of water resources based on PET and DI would help the development of climate change adaptation strategies for rice production in the 21st century. In addition, the studies on climate change impact would be facilitated using specialized data tools, e.g., readGrADSWrapper, for geospatial analysis of climate data.

• Science of Emotion and Sensibility
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• v.24 no.1
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• pp.91-104
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• 2021

This study explored users' emotional states identified from the wake-up words -"Hi, KIA!"- using a machine learning algorithm considering the user interface of passenger cars' voice. We targeted four emotional states, namely, excited, angry, desperate, and neutral, and created a total of 12 emotional scenarios in the context of car driving. Nine college students participated and recorded sentences as guided in the visualized scenario. The wake-up words were extracted from whole sentences, resulting in two data sets. We used the soundgen package and svmRadial method of caret package in open source-based R code to collect acoustic features of the recorded voices and performed machine learning-based analysis to determine the predictability of the modeled algorithm. We compared the accuracy of wake-up words (60.19%: 22%~81%) with that of whole sentences (41.51%) for all nine participants in relation to the four emotional categories. Accuracy and sensitivity performance of individual differences were noticeable, while the selected features were relatively constant. This study provides empirical evidence regarding the potential application of the wake-up words in the practice of emotion-driven user experience in communication between users and the artificial intelligence system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.583-592
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• 2020

This study assessed source depletion in the vadose zones of contaminated sites. The possible range of infiltration rate in Korea was statistically analyzed. The results showed a trend of decreasing leachate concentration of 13 pollutants used for risk assessment. Among them, benzene, ethylbenzene, toluene, and xylene showed a lower leachate concentration in groundwater over time due to their low distribution coefficient and also possible biodegradation effects. The average values of the relative concentration could be taken as a default index due to a very small range of uncertainties. In the case of heavy metals, it was shown that the leachate concentration in a pollutant does not decrease over time. Considering the annually different infiltration, a site-specific source-depletion scenario was applied to Cheongju in North Chungcheong Province. The result was expressed as a time series of the relative concentration of the leachate concentration, and this was compared to the trend by averaged Korean infiltration. Finally, an open-source code that used Python was used to help calculate the leachate concentration by this site-specific infiltration scenario.

• Journal of Nutrition and Health
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• v.43 no.5
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• pp.533-542
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• 2010

The objective of this study is to provide basic information and policy implications needed to balance the supply and demand for dietitian by projecting supply and demand for dietitian. The data from the Ministry of Health Welfare and Family on the number of licensed nutritionist, resident registration data of the Ministry of Public Administration and Security, and health insurance qualification data of the National Health Insurance Corporation were used to examine the current status of supply. To project the supply of nutritionist workforce, the in-out moves method and demographic method were used. The ratios of nutritionist to population and GDP, and that of other countries were applied as the demand projection method. According to the study results, the projection on the imbalance of supply and demand for dietitian by year 2021 differs depending on the method used. First, according to the results based on age-adjusted population ratio, there is an oversupply of 1,643 dietitians in year 2010, and 2,076 dietitians in year 2020. Second, although the projection on the imbalance of the supply and demand for dietitian differs depending on whether the GDD is calculated in won(￦) or dollar($). it is expected that there will be an oversupply in general. Third, as to the scenario using the nutritionist ratio in foreign countries, the oversupply of dietitian is likely in Korea, under any scenario, when comparing the nutritionist supply projection with the demand projection based on the nutritionist ratio in the United States. However, the projection of the supply and demand varies in each scenario when the European nutritionist ratio is applied. Under European 'scenario 1', an oversupply is expected, whereas under 'scenario 2', a shortage of supply is expected. A careful approach is required in interpreting the supply and demand projection using criteria of other countries, because dietitian assumes different roles and functions in each country. Although a slight oversupply of nutritionist workforce is projected, it does not cause a major problem as the demand for diet therapy is expected to rise due to aging and the increase of chronic diseases, and as the demand for clinical dietitians in hospitals increases. Accordingly, the demand for dietitians will rise and, in this context, the oversupply of nutritionist will not incur much problem. However, the nutritionist qualification is much too open in Korea, and this has a negative effect on the quality of the nutritionist workforce. Therefore, it is important that the nutritionist qualifications and requirements are reinforced in the future, enhance the quality level of the nutritionist supply, and maintain the balance between the supply and demand.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.8
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• pp.2814-2832
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• 2014

As information society matures to an even higher level and as information technology becomes a necessity to our everyday lives, the needs to develop, support and satisfy personal and social needs without the limitation of time, space, and location have become a vital point to everyday lives. Smartphone users are increasing at a staggering rate but the research on mobile-Learning model and the implementation of m-Learning scenario are still behind the needs of the users. Therefore, this paper focuses on the design of 'repeatable and short-spanned m-Learning model' to meet the needs of the learners who are on the go and on the move with their smartphones. Smartphone users frequently reach out for their phones but compare to the frequencies, the actual span of time they spend per use are relatively and surprisingly short. One way to understand this phenomenon is that the users tend to immediately replace their smartphones with laptops or desktops whenever they are available. A leaning model was needed to reflect this short and frequent use, a use that is solely based on the smartphone environment. This proposed learning model first defines this particular setting and implements the model to real smartphone users over an 8 week period. To understand whether different learning backgrounds can influence this model, different schools with online and offline learning channels participated in the experiment. User survey was conducted after the experiment to get a better understanding of the smartphone users. Pretest and posttest were conducted before and after the experiment and the data were validated and analyzed using SPSS version 18.0 for PC. Preliminary descriptive statistics, multiple regression and cross validation was conducted for the analysis. The results showed that the proposed English Listening and Comprehension Mobile Digital Textbook (ELCMDT) had a positive effect on the learners in general and was more effective for learners who were already experienced with online learning.

• Journal of the Korean Society of Safety
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• v.28 no.6
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• pp.49-56
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• 2013

The statistics of recent accidents in warehouses show that a heavy toll of lives were produced by various accidents, e.g. collision, overturn, fall, slip, exposure to harmful substances or environments, etc. Of significant concern amongst them is the collision, especially the collision between forklift and storage rack structure. Accordingly, this study focuses on behavioral characteristics of rack structure subjected to dynamic impact loading of a forklift. For this purpose, time-domain response analysis has been performed on a standard 2-bay six-story rack structure consisting of columns, beams and bracing members with perforated open section. In order to investigate the most critical scenario, the impact loads are applied in both down-aisle and cross-aisle directions, and the impact locations are also varied along the shelves of the palettes. In order to deal with storage distributions, three types of rack structures are further taken into account: original empty rack structure with no storage, half-loaded rack structure and fully-loaded rack structure. The numerical simulation results demonstrate that the dynamic characteristics of the rack structure are significantly dependent on the distribution of the storage goods and its natural period varies from 0.24sec to 1.06sec, approximately 4.4 times. Further, the parametric studies show that the forklift impact is most critical to the safety of the rack structure when it collides either at the base or at the top of the rack structure.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.287-297
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• 2012

In order to prepare for the introduction of the E-Discovery system from the United States and to cope with some causable changes of legal systems, we propose a general E-Discovery process and essential tasks of the each phase. The proposed process model is designed by the analysis of well-known projects such as EDRM, The Sedona Conference, which are advanced research for the standardization of E-Discovery task procedures and for the supply of guidelines to hands-on workers. In addition, Machine Learning Algorithms, Open-source libraries for the Information Retrieval and Distributed Processing technologies based on the Hadoop for big data are introduced and its application methods on the E-Discovery work scenario are proposed. All this information will be useful to vendors or people willing to develop the E-Discovery service solution. Also, it is very helpful to company owners willing to rebuild their business process and it enables people who are about to face a major lawsuit to handle a situation effectively.