• Journal of Food Hygiene and Safety
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• v.31 no.3
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• pp.176-185
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• 2016

This study was performed to investigate elementary school children's awareness on children's favorite foods and their consumption behavior of the foods. This study also focused on the association between the variables and gender/grade. We conducted a cross-sectional survey with direct interview among three hundreds and six elementary school children (188 boys and 118 girls) from 13 schools of a city of Korea, using a structured questionnaire. Among the overall proportion, more than 20% of the respondents did not know children's favorite foods and/or have no information source on the foods. More than 60% of the respondents consumed children's favorite foods more than 1 to 2 times a week. Only 16% respondents got information on children's favorite foods at home and 37% at school. There were significant correlations (p < 0.05) between gender/grades and knowledge/route of information on children's favorite foods. Boys had more knowledge than girls (p < 0.05), however they showed worse attitude on children's favorite foods and consumed more the foods. The higher grade children had more knowledge, better attitude and various routes of information on children's favorite foods (p < 0.05), but consumed more the foods. The results of this study indicate that there is a discrepancy between knowledge and attitude/behavior. This study also indicate that school food-service program and food hygiene/safety education in school and at home should be improved. Strong implementation of laws for regulation of selling adulterated food around elementary school may be another step in controlling consumption of the food by school children.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.802-808
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• 2019

DC motors are used extensively on shipboard, including as the ship's winch operating motor, owing to their simple speed control and excellent output torque characteristics. Moreover, they were used as propulsion motors in the early days of electric propulsion ships. However, mechanical rectifiers, such as brushes, used in DC motors have certain disadvantages. Hence, brushless DC (BLDC) motors are increasingly being used instead. While the electrical characteristics of both types of motors are similar, BLDC motors employ electronic rectifying devices, which use semiconductor elements, instead of mechanical rectifying devices. The inverter system for driving conventional BLDC motors uses a two-phase excitation method so that the waveform of the back electromotive force becomes trapezoidal. This causes harmonics and torque ripple in the phase current switching period in which the winding wire through which the current flows is changed. Researchers have studied and presented various methods to reduce the harmonics and torque ripple. This study applies a cascaded H-bridge multilevel inverter, which implements a proportional-integral speed current controller algorithm in the driving circuit of the BLDC motor for electric propulsion ships using a power analysis program. The simulation results of the modeled BLDC motor show that the driving method of the proposed BLDC motor improves the voltage waveform of the input side of the motor and remarkably reduces the harmonics and torque ripple compared with the conventional driving method.

• Journal of Internet Computing and Services
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• v.21 no.2
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• pp.39-48
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• 2020

Data mining techniques have been suggested to find efficiently meaningful and useful information. Especially, in the big data environments, as data becomes accumulated in several applications, related pattern mining methods have been proposed. Recently, instead of analyzing not only static data stored already in files or databases, mining dynamic data incrementally generated in a real time is considered as more interesting research areas because these dynamic data can be only one time read. With this reason, researches of how these dynamic data are mined efficiently have been studied. Moreover, approaches of mining representative patterns such as maximal pattern mining have been proposed since a huge number of result patterns as mining results are generated. As another issue, to discover more meaningful patterns in real world, weights of items in weighted pattern mining have been used, In real situation, profits, costs, and so on of items can be utilized as weights. In this paper, we analyzed weighted maximal pattern mining approaches for data generated incrementally. Maximal representative pattern mining techniques, and incremental pattern mining methods. And then, the application scenarios for analyzing the required commodity patterns in infants are presented by applying weighting representative pattern mining. Furthermore, the performance of state-of-the-art algorithms have been evaluated. As a result, we show that incremental weighted maximal pattern mining technique has better performance than incremental weighted pattern mining and weighted maximal pattern mining.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.681-689
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• 2019

Web usage pattern discovery is an advanced means by using web log data, and it's also a specific application of data mining technology in Web log data mining. In education Data Mining (DM) is the application of Data Mining techniques to educational data (such as Web logs of University, e-learning, adaptive hypermedia and intelligent tutoring systems, etc.), and so, its objective is to analyze these types of data in order to resolve educational research issues. In this paper, the Web log data of a university are used as the research object of data mining. With using the database OLAP technology the Web log data are preprocessed into the data format that can be used for data mining, and the processing results are stored into the MSSQL. At the same time the basic data statistics and analysis are completed based on the processed Web log records. In addition, we introduced the Apriori Algorithm of Web usage pattern mining and its implementation process, developed the Apriori Algorithm program in Python development environment, then gave the performance of the Apriori Algorithm and realized the mining of Web user access pattern. The results have important theoretical significance for the application of the patterns in the development of teaching systems. The next research is to explore the improvement of the Apriori Algorithm in the distributed computing environment.

• Industry Promotion Research
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• v.5 no.1
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• pp.47-52
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• 2020

In this study, parallel work-learning training, which was started in 2013 as a pre-employment promotion policy, is an important factor that determines the success or failure of training. As a time when various institutional supplementation is needed to encourage company participation, this study is to identify the factors of participation of companies participating in work-learning parallel. To this end, a questionnaire survey was conducted of companies participating in parallel work-learning in Chungnam, and the results were analyzed using the structural equation model. As a result of the study, the reason for the company's participation in parallel work-learning was firstly, 84% of government subsidy received education and training expenses. Second, 66% of workers were able to pay less than regular workers, and thirdly, it was easy to hire new employees in the field. 26%, 17% of them were invited by acquaintances for no particular reason. Therefore, the study suggests that participation in the work-learning parallel training contributes to the management costs, management of employee turnover, and human resource development. In future research, it is necessary to subdivide tests and estimates by conducting studies on regions, occupations, gender, wages, and years of service in Korea.

• Journal of the Korean Society for Environmental Technology
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• v.19 no.5
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• pp.427-434
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• 2018

This study analyzes the effect of public-private partnership for reduction of concentration of benzene that is emitted from Ulsan petrochemical complex. Despite the fact that from 2012 to 2016 each factory had been observing legal standards, according to measurements of concentrations of benzene by the monitoring station in Yeocheon-dong, Ulsan, for five successive years, benzene concentrations had been exceeding the environmental standards for air quality ($5{\mu}g/m^3$) by 1.4 to 1.8 times, resulting in endless civil petitions. On the other hand, in 2017, when a cooperation system was constructed across private, public and research institutions and actors, through the formation of a network for information-sharing among, and professional education to reinforcement of competency among the Ministry of Environment, the National Institute of Environmental Research, conglomerates, and local businesses of Ulsan, Benzene concentration became $4.25{\mu}g/m^3$, satisfying the atmosphere environmental standard. According to the analysis, cooperation built based upon mutual trust between the public sector and the civil sector has made it possible to solve, in a year, the regional environmental problem, i.e., excessive benzene concentrations for 5 years. Henceforth, along with research on measures to share and spread out advanced technology and case-studies, targeting other regions where benzene concentrations have not yet improved, research on methods to maintain benzene concentrations as they are is needed.

• New Physics: Sae Mulli
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• v.67 no.10
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• pp.1210-1219
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• 2017

We discuss the improvement in a general physics laboratory course by using a digital camera and a video tracking analysis open program. Because of recent breakthroughs in the CMOS technology for consumer-grade cameras and software improvements in vision analysis, these techniques can be applied to simple physical problems, which is, from an educational point of view, very important in introductory level physics. We have developed course materials for use in a general physics laboratory offered to undergraduate students both in the natural science and the engineering departments at 'P' University. In our course, 7 of the 10 courses in mechanics can be replaced by the simple guidelines given here. Four mechanics experiments, free fall, parabolic motion with a projectile, momentum conservation, and simple harmonic oscillation, were demonstrated using a video tracking analysis. We also present a simple manual, as well as new textbook, written in the Korean Language. We discuss advantages of not only the video tracking analysis but also attention during the experimental process. Our guideline can also be applied to high-school physics experiments.

• Journal of Broadcast Engineering
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• v.25 no.4
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• pp.518-527
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• 2020

360 VR technology is used not only in movies, but also in performing arts such as music, theater, dance, and so on due to the characteristics of immersion and presence. The technology allows the audience can be perceived a feel of participation in a story. This study is conducted an analysis of the techniques of 360 video shooting in order to find the answers of the following questionaries: how to make viewers enhance to a better understanding of a space, how to make the viewer feel comfortable ceding control of the experience, how to generate greater empathy with a 360 video. Thirty cases were analysed 360-degree videos of live performances performed on stage among 360-degree images of music performance content shared on Youtube from 2015 to 2020. The result shows that live performances are performed with the audience, so the stage shape and the layout of the audience seats are preferred to the characteristics of the performance. It was also shown that directing using a 360 VR camera was also greatly affected by the stage and audience placement. The stage is manly classified into three types, and the camera layout and characteristics mainly used are organized according to the number of 360 VR cameras, whether fixed or mobile cameras are used.

• Journal of Environmental Health Sciences
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• v.46 no.4
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• pp.398-409
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• 2020

Objectives: This study aimed to evaluate environmental exposure to tobacco-specific nitrosamines (TSNAs) by conducting an analysis of the concentration of TSNAs in deposited dust collected from a fertilizer plant and the surrounding village, a simulation of high-temperature drying of tobacco waste, and CALPUFF modeling. Methods: The raw materials of the products, deposited dust (inside and outside the plant and residential area), soil, and wastewater were sampled and the TSNA concentrations were analyzed by LC-MS/MS. As the plant was closed down before the investigation, simulation tests were conducted to confirm the substances discharged during high-temperature (300℃) drying of tobacco waste. CALPUFF modeling was performed to identify the area of influence due to exposure to TSNAs. Results: TSNAs were detected in organic fertilizers estimated to contain tobacco waste, deposited dust, and soil collected from inside and outside the plant. N'-nitrosonornicotine (NNN), 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK), and N'-nitrosoanatabine (NAT) components were detected in five of 15 deposited dust samples collected from the residential area around the plant, while TSNAs were not detected in the five sampling points in the control area. Also, the simulation test for the high temperature drying of tobacco waste found emissions of TSNAs. The CALPUFF modeling results showed that the survey area was likely to be included in the area of influence of TSNA emissions from the plant. Conclusions: It is estimated that harmful tobacco ingredients such as TSNAs were dispersed in nearby areas due to the illegal use of tobacco waste as a raw material to produce organic fertilizers at the plant. These findings assume that the residents have been exposed to TSNAs and suggest that the need for the establishment of measures to manage environmental health.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.411-416
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• 2020

An optical arrangement has been set inside a photo-spectrometer to measure the reflectance of IR optics materials in mid IR range. The optical arrangement consists of equally spaced 4 gold coated full reflecting mirrors with the incidence angle of 45°. Baseline beam intensity I_B has been measured while the beam proceeds through the 4 mirrors. Reflectance of a mirror has been estimated from the I_B. And the beam intensity I_S with the specimen in the optical path has been measured with the 4th mirror replaced with the specimen. Reflectance of the specimen has been estimated from the value of I_S/I_B. Then the estimated reflectance has been put in Fresnel equation relating reflectance and refractive index(RI) to estimate the RI of the material. Measurement has been made for sapphire, germanium, magnesium fluoride, and zinc sulfide. The estimated RI of the materials are closely matching with reference data and the maximum difference less than 2% over the wavelength range 3-5㎛ for all materials tested. As an FT-IR photo-spectrometer with a broadband wavelength infrared light source is used, this method has the advantage of measuring the refractive index at multiple wavelengths in a single measurement.