• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.84-91
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• 2017

Recent years have witnessed the increased usage of flammable metals, such as aluminum or magnesium, in wide range of high-tech industries. These metals are indispensable for the improvement of physical properties of materials as well as the design capability of the final product. During the process, unwanted metal dusts could be released to the environment. This can lead to an occupational health and safety issues. Due to their flammable nature, more serious problem of an explosion can happen in extreme cases. The explosion is the combustion of tiny solid particles and vapor mixture, caused by pyrolysis. This complex composition makes engineering analysis more difficult, compared to simple gas explosions or vapor cloud combustions. The study was conducted to assess this light metal dust explosion in an effort to provide the bases for a risk assessment. Dust explosion characteristics of each material was carefully evaluated and an appropriate analysis tool was developed. A comprehensive database was also constructed and utilized for the calibration of the developed response model and the verification for its accuracy. Subsequently, guidelines were provided to prevent dust explosions that could occur in top-notch industrial processes.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.41-49
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• 2015

The amount of energy consumed in air ventilation systems of public facilities accounts for 40% of their total energy consumption. To reduce their energy consumption, applying variable speed operation controlled by an inverter with a high-efficiency motor is suggested. Since these methods require higher initial investment costs compared to the existing systems, economic evaluation should be conducted from a long-term perspective. While LCCA(Life Cycle Cost Analysis) model is useful to estimate net savings of alternatives that differs with respect to initial costs and operating costs, the environmental burdens are not considered. On the contrary LCA(Life Cycle Assesment) model is suitable to assess environmental impacts associated with the stages of a product's life but it does not consider costs. In this study, the high-efficient motors are introduced into the air ventilation system of a subway station and a comprehensive analysis on the economic and environmental impacts of the proposed method is conducted by using LCCA and LCA model.

• Education of Primary School Mathematics
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• v.17 no.2
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• pp.95-111
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• 2014

The purpose of this study is to determine the relationship between metacognition and math creative problem solving ability. Specific research questions set up according to the purpose of this study are as follows. First, what relation does metacognition has with creative math problem-solving ability of mathematically gifted elementary students? Second, how does each component of metacognition (i.e. metacognitive knowledge, metacognitive regulation, metacognitive experiences) influences the math creative problem solving ability of mathematically gifted elementary students? The present study was conducted with a total of 80 fifth grade mathematically gifted elementary students. For assessment tools, the study used the Math Creative Problem Solving Ability Test and the Metacognition Test. Analyses of collected data involved descriptive statistics, computation of Pearson's product moment correlation coefficient, and multiple regression analysis by using the SPSS Statistics 20. The findings from the study were as follows. First, a great deal of variability between individuals was found in math creative problem solving ability and metacognition even within the group of mathematically gifted elementary students. Second, significant correlation was found between math creative problem solving ability and metacognition. Third, according to multiple regression analysis of math creative problem solving ability by component of metacognition, it was found that metacognitive knowledge is the metacognitive component that relatively has the greatest effect on overall math creative problem-solving ability. Fourth, results indicated that metacognitive knowledge has the greatest effect on fluency and originality among subelements of math creative problem solving ability, while metacognitive regulation has the greatest effect on flexibility. It was found that metacognitive experiences relatively has little effect on math creative problem solving ability. This findings suggests the possibility of metacognitive approach in math gifted curricula and programs for cultivating mathematically gifted students' math creative problem-solving ability.

• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.12-22
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• 2018

The US government has enacted the Food Safety Modernization Act (FSMA) in 2011, which is being phased in and planned. The final Rules of Produce Safety focus on biological hazards related to agricultural production, harvesting, packaging and storage, which are being phased in since 2017 depending on farm scale. As a result of comparison with the Korean-GAP (Good Agricultural Practices) standards, it is difficult to compare the two standards to be compared with each other by 1:1. However, many of the Korean-GAP standards are similar to FSMA Produce Safety rules. However, the Korean-GAP standards can be judged differently according to the evaluator as a comprehensive standard, so the details of the standards need to be reinforced. In terms of the provisions, the Korean-GAP standards are the most appropriate for the safety of workers (FSMA Subpart D), followed by livestock and wild animals (FSMA Subpart I), buildings, equipment and tools (FSMA Subpart L) and harvesting activities (FSMA Sub-part K). However, there are some weaknesses in the field of agricultural water management (FSMA Subpart E) and farm manager's qualifications and training (FSMA Subpart C), and the response to the biological soil amendments of animal origin and human waste (FSMA Subpart F) is weak. The FSMA regulation is not a certification standard, but it is expected that the marbling effect, which is the standard laid down by the United States leading the world food safety standards, is expected to be considerable. Therefore, we hope that the review of the Korean-GAP standards will help improve the quality of agricultural products and expand our exports, since the standard for responding to microbiological safety emphasized in the FSMA regulations is the Korean-GAP standard.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.490-498
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• 2010

HCFC-22 (chlorodifluoromethane, $CHClF_2$), one of the major components in various refrigeration, is emitted mostly from developing countries, as its consumption is not limited until 2013 by the Montreal Protocol. In addition, HFC-23 (trifluoromethane, $CHF_3$), a by-product in the manufacture of HCFC-22, is also a powerful greenhouse gas. Here, we discuss the regional emission characteristics of these compounds based on high-frequency in-situ measurements using the "Medusa" GC-MS system. HCFC-22 and HFC-23 baseline concentrations measured at Gosan (Jeju Island, Korea) from November 2007 to December 2008 increased by 1.8 ppt/yr and 0.6 ppt/yr, respectively. Pollution events of these compounds were observed, very frequently (e.g., ~2~3 times) at Gosan than baseline levels. All the measurement data were divided into four groups by simultaneously considering the ratio (HFC-23/HCFC-22) and concentration (HCFC-22) at Trinidad Head (TH, California, USA). The residence time of trajectories were then analyzed in each of the four groups. The results exhibited the existence of a strong correlation with air mass origin for each group: 1) Air masses originating from Siberia in the north and from the Pacific in the south had ratios of 0.08~0.12 and concentrations of 196.9~254.3 ppt which is highly comparable to background air at TH. 2) Air masses passing over the Southern China exhibited similar ratios but higher HCFC-22 concentrations. 3) Air masses passing over the Northern China had ratios of 0.12~0.21. 4) Air masses passing over Korea and/or Japan had ratios of 0.01~0.08. Our results suggest that the HFC-23/HCFC-22 ratio can be used as a good indicator for the assessment of the pollution with Chinese origin. We also confirmed differences in air masses traveling over Northern and Southern China, most likely due to differences in air mass travelling speed over these regions before arriving at Gosan. This signature may be treated as one of the critical components in identifying the emission sources from different parts of China.

• Journal of Wetlands Research
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• v.21 no.spc
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• pp.123-133
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• 2019

This study analyzed the surface temperature mitigation effect of wetlands during cold waves (below -12℃ from January to February) and heat waves (above 33℃ from July to August) in 2018. We used Terra/Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Daytime and Nighttime Land Surface Temperature (LST) product, and the maximum and minimum air temperature observed at 86 stations of Korea Meteorological Administration (KMA). For the cold wave analysis, the LST of Terra MODIS nighttime was the highest at forest area with -12.7℃, followed by upland crop and wetland areas of -12.9℃ and -13.0℃ respectively. The urban area showed the lowest value of -14.4℃. During the heat wave, the urban area was the highest with + 34.6℃ in Aqua MODIS LST daytime. The wetland area was + 33.0℃ showing - 1.6℃ decrease comparing with urban area.

• Journal of Nutrition and Health
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• v.18 no.4
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• pp.283-292
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• 1985

A sanitary quality of a university foodservice establishment was assessed in terms of time and temperature, pH and Aw, and microbiological evaluation. Critical control points during various phases in product flow of fried fish cake soup were identified using hazard analysis concept. The results are summarized as follows : 1) Time and temperature data indicated that phases of holding ingredients at room temperature after cooking, and hot - holding of soup before assembly were critical. 2) pH and Aw values were in favorable for microbial growth. 3) Microbiological data indicated that microbial quality of ingredients was in poor condition. A holding practice of cooked ingredients at room temperature might provide the chance for microbial contamination and multiplication. Hot - holding time and temperature of soup should be strictly controlled to assure the food safety, since the microbial quality of serving food can be directly influenced by the hot - holding temperature of soup. 4) Microbiological test results for food containers, equipments, working surfaces, and supplies indicated that sanitary conditions of earthenware, gloves, wiping cloths and cutting board should be improved promptly. 5) Critical control points identified were : ingredients, pre - preparation, post - preparation, and holding before assembly and service. 6) Guidelines for the effective quality control program for this operation were suggested.

• Journal of KIISE:Software and Applications
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• v.31 no.6
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• pp.716-727
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• 2004

Component-based software development (CBD) technology has been widely accepted as a new effective paradigm for building software systems with reusable components, consequently reducing efforts and shortening time-to-market. Hence, components should provide standard or common functionalities in a domain, yielding a higher level of reusability. Especially, micro-level variability within the commonality should also be modeled so that a product member-specific business logic or requirement can be supported through component tailoring or customization The importance of commonality and variability (C&V) analysis has been emphasized in several CBD methods, but they lack of well-defined systematic process, detailed instructions, and standard artifact templates. As the result, the development of components has been carried out in ad-hoc fashion, depending on developer's experience. In this paper, we propose a systematic process and work instructions to design components. The process consists of phases and their activities and each activity is specified with detailed instructions and artifact templates in order to facilitate effective development of components. To verify a feasibility of the propose method, a case study in a banking domain and comparison and assessment between the proposed method and other methods are additionally provided. With proposed processes and instructions, reusability and efficiency of developing components can be better supported.

• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.524-540
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• 2014

The purpose of this study was to analyze effect young children's temperament and teacher-child relationship on child's leadership. Subject were 3~5 years old 333 kindergarten young children. young children's parents answered young children's temperament questionnaire. young children's teacher answered young children's temperament and teacher-child relationship questionnaire. The research tools used in this study were the questionnaire for assessment scale of young children's temperament, teacher-child relationship and young children's leadership. To analyze effect young children's temperament and teacher-child relationship on young children's leadership, questionnaires were reconstruted from existing questionnaires. Using SPSS statistics 20 for window program, Scheff$\acute{e}$ verification, pearson product moment correlation, mutiple regression analysis, tolerance, variance inflation factor and VIF were used to analyze the data. Results of this study are summarized as follows: In child's temperament, regularity, in teacher-child relationship, closerelationship, in young children's leadership, goal achivement competence were appeared most high. In young children's temperament, adaptabilituy and durability effected on child's leadership positively. In teacher-child relationship, closerelationship and dependency relationship effected on young children's leadership positively.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.2
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• pp.191-204
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• 2005

Building and furnishing materials and consumer product are important sources of volatile organic compounds(VOCs) and other aldehydes in the indoor environment. Some available evidence indicates that VOCs can cause adverse health effects to the building occupants and contribute to some of the symptoms of what we call, 'Sick House Syndrome' in Korea. The aims of this study were to evaluate the efficiency of emission system and to investigate comparison of the emission characteristics of different building materials such as wall-papers, paints, and adhesives. The emission of VOCs from building materials were determined in the small chambers defining the temperature, relative humidity, and ventilation rate in this study. VOCs were sampled for 20 minutes using Tenax-TA tubes and analysed by GC-MS with thermal desorption. The stability of conditions for temperature and relative humidity in this small chamber system showed that the fluctuation of temperature was between 25.4$\pm$0.3$^{\circ}C$ and that of relative humidity was 50.2$\pm$0.6$\%$ under the airflow rate of 167 mL/min. The emission tests from building materials resulted in TVOC emission rates of 0.011 $\~$ 3.108 mg/m$^{2}$h after 7 days. The general wall-papers emitted toluene abundantly and the natural wall-papers mainly emitted n-butanol and a minor amount of alkanes compound such as n -tetradecane. The remainder consisted of toluene, m,p -xylene, and styrene. The paints mainly emitted toluene and the adhesives mainly emitted chloroform as well as toluene. As a result, this study is expected to suggest meaningful data for future studies in exposure control through selecting healthy building materials and for the establishment of guidelines for various building materials in Korea.