• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.980-990
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• 2004

In this paper, we propose the dynamic bandwidth allocation algorithm for the IEEE802.3ah Ethernet Passive Optical Network(EPON) system to provide the fairness among terminals, and evaluate the delay-throughput performance by simulation. For the conventional EPON systems, an Optical Line Termination (OLT) schedules the upstream bandwidth for each Optical Network Unit (ONU), based on its buffer state. This scheme can provide a fair bandwidth allocation for each ONU. However, it has a critical problem that it does not guarantee the fair bandwidth among terminals which are connected to ONUs. For an example, we assume that the traffic from a greedy terminal increases at a time. Then, the buffer state of its ONU is instantly reported to the OLT, and finally the OW can get more bandwidth. As a result, the less bandwidth is allocated to the other ONUs, and thus the transfer delay of terminals connected to the ONUs gets inevitably increased. Noting that this unfairness problem exists in the conventional EPON systems, we propose a fair bandwidth allocation scheme by OLT with considering the buffer state of ONU as welt as the number of terminals connected it. For the performance evaluation, we develop the EPON simulation model with SIMULA simulation language. From the result of the throughput-delay performance and the dynamics of buffer state along time for each terminal and ONU, respectively, one can see that the proposed scheme can provide the fairness among not ONUs but terminals. Finally, it is worthwhile to note that the proposed scheme for the public EPON systems might be an attractive solution for providing the fairness among subscriber terminals.

• Journal of The Korean Association For Science Education
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• v.34 no.8
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• pp.731-744
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• 2014

Extracting students' own culture and resources as main sources in science class, we begin a research to explore teaching and learning settings that are more responsive to adolescents. This study has been designed to explore the funds of knowledge that students bring into middle school science class. It also focused on the features of teaching and learning settings that stimulated the autonomous inflow of students' funds of knowledge as resources of science learning. Data from participant observations and in-depth interviews with 7th grade students were qualitatively analyzed based on grounded theory. We found that students' funds of knowledge were formed from their family life, neighbor communities, peer group, and pop culture. The funds of knowledge based on peer culture emerged as the most salient factor of students' enhanced participation and utterance. Common features of classes that stimulated the inflow of funds of knowledge were analyzed to be: (1) hybrid spaces for learning designed in advance: (2) sharing and enlargement of the funds of knowledge that has been brought into the class: and (3) common orientation of the community of practice for knowledge co-construction and shared outcomes. From these findings, this paper discussed the educational implications for promoting students' potential resources to actual sources of science class. It also discussed students' development of participation specifically among the generally marginalized students. Science classes based on the funds of knowledge of students offer an increased possibility of knowledge co-construction through the hybridized interactions of student's everyday lives and science knowledge and lead to more meaningful learning experiences.

• Journal of Nutrition and Health
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• v.47 no.4
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• pp.300-312
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• 2014

Purpose: This study was performed to examine the sanitary knowledge level and degree of HACCP (hazard analysis critical control point) practice in school culinary staff in order to provide basic information for improving hygiene of school meals. Methods: Exactly 305 culinary staff members were selected from elementary, middle, and high schools in 14 cities and rural areas, including whole administrative districts in Chungnam province. Surveyed schools were selected by convenience sampling, and one subject was selected randomly from each school. Surveys were taken by self-administered questionnaires developed by researchers and questionnaire were distributed and collected by postal mail. Results: Sanitary education administered by school dietitians to culinary staff was more frequent and longer in elementary schools, followed by middle and high schools (p < 0.001). Sanitary knowledge level and degree of HACCP practice, except for a few CCP or CP of culinary staff, were highest in elementary schools and middle school followed by high schools (p < 0.05), respectively. School class was negatively correlated with sanitary knowledge level of culinary staff (p < 0.01), and frequency of sanitary education was positively correlated with sanitary knowledge level of culinary staff (p < 0.01). Sanitary knowledge level of culinary staff was positively correlated with degree of HACCP practice (p < 0.01). School class, daily frequency of meal service, work experience, rice washing machine, and total score of sanitary knowledge were significant variables influencing degree of HACCP practice in culinary staff. Conclusion: The above results show that the following points should be considered to improve hygiene of school meals. Sanitary education should be administered more frequently by school dietitians to culinary staff, especially to those in high schools, which showed the lowest sanitary knowledge level and degree of HACCP practice. In addition, facilities and equipment required for HACCP practice should be supported in small-sized elementary schools.

• Journal of Life Science
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• v.27 no.10
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• pp.1152-1160
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• 2017

A unicellular green alga was axenically isolated from a tidal pool on Ulleung-do, Korea. Morphological, molecular, and biochemical analyses revealed that the isolate belonged to Auxenochlorella protothecoides. The current study is the first record of this species in Korea. The microalgal strain was named as A. protothecoides MM0011 and its growth, lipid and pigment compositions, and biomass properties were investigated. The strain is able to thrive in a wide range of temperatures ($5{\sim}35^{\circ}C$) and to withstand up to 1.5 M NaCl. The results of GC/MS analysis showed that the isolate was rich in nutritionally important polyunsaturated fatty acids (PUFAs). Its major fatty acids were linoleic acid (27.6%) and ${\alpha}-linolenic$ acid (39.6%). Thus, this indigenous microalga has potential as an alternative source of ${\omega}3$ and ${\omega}6$ PUFAs, which currently come from fish and plant oils. Also, the HPLC analysis revealed that the value-added antioxidant, lutein, was biosynthesized as the accessory pigments by the microalga. A proximate analysis showed that the volatile matter content was 85.6% and an ultimate analysis indicated that the gross calorific value was $20.3MJ\;kg^{-1}$. Since 40.5% of total nitrogen and 27.9% of total phosphorus were removed from the medium, respectively, it also has potential as a feedstock for biofuel applications which could be coupled to wastewater treatment. In addition, the biomass may also serve as an excellent animal feed because of its high protein content (51.4%). Therefore, A. protothecoides MM0011 shows promise for application in production of microalgae-based biochemicals and as a biomass feedstock.

• Proceedings of The Korean Society of Health Promotion Conference
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• 2004.10a
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• pp.111-129
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• 2004

This paper develops the argument that the 'Healthy Cities Approach' extends beyond the boundaries of officially designated Healthy Cities and suggests that signs of it are evident much more widely in efforts to promote health in the United Kingdom and in national policy. It draws on examples from Leeds, a major city in the north of England. In particular, it suggests that efforts to improve population health need to focus on the wider determinants and that this requires a collaborative response involving a range of different sectors and the participation of the community. Inequality is recognised as a major issue and the need to identify areas of deprivation and direct resources towards these is emphasised. Childhood poverty is referred to and the importance of breaking cycles of deprivation. The role of the school is seen as important in contributing to health generally and the compatibility between Healthy Cities and Health Promoting Schools is noted. Not only can Health Promoting Schools improve the health of young people themselves they can also develop the skills, awareness and motivation to improve the health of the community. Using child pedestrian injury as an example, the paper argues that problems and their cause should not be conceived narrowly. The Healthy Cities movement has taught us that the response, if it is to be effective, should focus on the wider determinants and be adapted to local circumstances. Instead of simply attempting to change behaviour through traditional health education we need to ensure that the environment is healthy in itself and supports healthy behaviour. To achieve this we need to develop awareness, skills and motivation among policy makers, professionals and the community. The 'New Health' education is proposed as a term to distinguish the type of health education which addresses these issues from more traditional forms.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.224-238
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• 2022

North Korea has actively participated in the international community related to environmental agreements. It has proposed various environmental policies internally since the Kim Jong-un regime. In particular, it emphasizes activities related to climate change response, the Sustainable Development Goals, and the conservation of ecosystems including forests and wetlands. In this study, a new security cooperation plan was proposed with an understanding of the climate crisis and environmental regime as a starting point. To this end, trends and recent activities for climate-environment cooperation in the international community and on the Korean Peninsula were analyzed. In addition, North Korea's conditions for cooperation on the Korean Peninsula, technology demand, and the projected future environment of the Korean Peninsula were dealt with. Ultimately, through advice of experts, we were able to discover cooperation agendas by sector and propose short-term and long-term environmental cooperation strategies for the Korean Peninsula based on them. In this study, conditions and directions for cooperation in fields of climate technology, biological resources, air/weather, water environment, biodiversity, renewable energy, bioenergy, and so on were considered comprehensively. Among 21 cooperation agendas discovered in this study, energy showed the largest number of areas. Renewable energy, forest resources, and environmental and meteorological information stood out as agendas that could be cooperated in the short term. As representative initiatives, joint promotion of 'renewable energy' that could contribute to North Korea's energy demand and carbon neutrality and 'forest cooperation' that could be recognized as a source of disaster reduction and greenhouse gas sinks were suggested.

• Korean Journal of Food Science and Technology
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• v.48 no.2
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• pp.133-141
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• 2016

The physicochemical properties, antioxidant capacities, and sensory optimization of taro (Colocasia esculenta) under different aging conditions were investigated to develop black taro. Black taro was processed in three steps (steaming: $95{\pm}3^{\circ}C$ for 1 h; aging: 85, 90, $95^{\circ}C$ for 20, 40, and 60 h; drying: $60^{\circ}C$ for 24 h) and ground into a powder for all experiments. Black taro showed an increased crude fiber content and browning index compared to raw taro. Calcium oxalate contents, reducing sugar contents, moisture contents, and lightness values were decreased during the processing of taro. Improvements in total polyphenol content and antioxidant activity (DPPH, ABTS, FRAP) were observed in the black taro samples aged at higher temperature. Response surface methodology was used for sensory optimization, and the optimum aging conditions with the highest acceptance values were found to be $88.73^{\circ}C$ for 39.50 h for taste, and $88.82^{\circ}C$ for 42.60 h for overall acceptance.

• Journal of Food Hygiene and Safety
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• v.23 no.3
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• pp.239-247
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• 2008

Objective of this study was to investigate residual the levels of heavy metals in rice grain and soils of "Top-Rice" and common rice cultivation areas from 2005 to 2007. Soil and rice grain samples were taken from 33 "Top-rice" areas and neighboring paddies, and analyzed for the elements using ICP-OES and ICP-TOF-MS after acid digestion. A concentration of arsenic in paddy soil was 1.33 mg/kg which was below 1/5-1/11 fold of the threshold levels(concern: 4 mg/kg, action: 10 mg/kg), and paddy soil was 0.06 mg/kg of Cd(cadmium) being below 1/25-1/67 fold of the limits(concern: 1.5 mg/kg, action: 4 mg/kg). A level of Cu(copper) in paddy soil was 4.57 mg/kg which was below 1/11-1/27 fold of the threshold levels(concern: 50 mg/kg, action: 125 mg/kg), and Pb(lead) concentration in paddy soil was found to be a 4.68 mg/kg. In addition, Hg(mercury) concentration in paddy soil was to be a 0.03 mg/kg, which was below 1/131-1/328 fold of the threshold levels(concern: 4 mg/kg, action: 10 mg/kg). The average concentrations of As, Cd, Cu, Pb and Hg in the polished rice samples were 0.037, 0.043, 0.280, 0.048 and 0.002 mg/kg, respectively. These levels are lower than those of other countries in rice grains. Assuming the rice consumption of 205.7 g/day by total dietary supplements in Korea, the amount of total weekly metal intake of As, Cd, Cu, Pb and Hg by polished rice were estimated to be 0.0892, 1.035, 6.712, 1.161 and 0.054 ${\mu}g/kg$ body weigh/week, respectively. The PTWI(%) of As, Cd, Cu, Pb and Hg were 5.95(inorganic arsenic), 0.26(total arsenic), 14.79, 0.19, 4.65 and 1.07% estimated to be 0.0892, 1.035, 6.712, 1.161 and 0.054 ${\mu}g/kg$ body weigh/week, respectively. In conclusion, it was appeared that the heavy metals contamination in the brown and polished rice should not be worried in Korea.

• Journal of Nutrition and Health
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• v.50 no.4
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• pp.402-414
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• 2017

Purpose: The purpose of the study was to evaluate the status of safety accidents and importance-performance analysis (IPA) between regular and non-regular employees in industry foodservices. Methods: The participants were regular employees (n = 119) and non-regular employees (n = 163) in industry foodservices in the Jeonbuk area. Demographic characteristics, status of safety accidents, safety education, and importance and performance status were assessed using a self-administered questionnaire. Results: Approximately 66.4% of regular employees and 53.4% of non-regular employees experienced safety accidents (p < 0.05). Types of safety accidents of regular and non-regular employees were mostly burns, and causes were mostly from their own negligence. Approximately 98.3% of regular employees and 95.1% of non-regular employees experienced safety education. Approximately 88.9% of regular employees and 96.8% of non-regular employees received safety education from dietitians. Approximately 41.9% of regular employees and 50.0% of non-regular employees had difficulty applying the contents of safety education due to lack of time during work. As a result of IPA, regular and non-regular employees were aware of the importance of the following and performed them well: 'Clean the floor of the work place', 'Arrange in the work area', 'Wear safety shoes', 'Check for heater cord', and 'Safety cooking when using oil'. On the other hand, they were not aware of the importance of the following and performed them insufficiently: 'Check for the MSDS', 'Aware of chemical signs', 'Wear protection gloves etc.', 'Do stretching exercise', and 'Using ancillary tools'. Conclusion: Therefore, it is necessary to improve the consciousness of dietitians for effective application of safety education contents, development of contents, especially MSDS, and related things.