• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.72-77
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• 2017

Lighting systems in modern society has been developed using a combination of IT technology and LED lighting for the purpose of bringing about changes in human-centered natural lighting and to take advantage of the efficient management and energy saving of LED lighting. In this paper, we propose an LED lighting control system that can control the color temperature and brightness of LED lighting composed of 3000K Warm LEDs and 6000K Cool LEDs by using an Arduino Due and wireless communication technology such as Bluetooth and Zigbee. The Arduino Due allows the color temperature of the lighting to be adjusted in several steps by controlling the duty rate and enables many lights to be controlled using Zigbee communication capable of 1: N multiple communication. By using Bluetooth communication, it is possible to easily control the LED lighting by means of a smartphone application, thereby enhancing the convenience for the user. The wireless communication based LED lighting control system implemented in this study cannot only provide human-centered lighting through its color temperature control from 3067K to 5960K and illumination control, but can also reduce the power consumption and be used as a natural-friendly lighting system.

• Advances in nano research
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• v.8 no.4
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• pp.323-333
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• 2020

In recent years, there has been an upsurge for the usage of buckling restrained braces (BRB) rather than ordinary braces, as they have evidently performed better. If the overall brace buckling is ignored, BRBs are proven to have higher energy absorption capacity and flexibility. This article aims to deliberate an economically efficient yet adequate type of all-steel BRB, comprised of the main components as in traditional ones, such as : (1) a steel core that holds all axial forces and (2) a steel restrainer tube that hinders buckling to occurr in the core; there is a more practical detailing in the BRB system due to the elimination of a filling mortar. An investigation has been conducted for the proposed rectangular-tube core BRB and it is hysteric behavioral results have been compared to previous researches conducted on a structure containing a similar plate core profile that has the same cross-sectional area in its core. A loss of strength is known to occur in the BRB when the limiting condition of local buckling is not satisfied, thus causing instability. This typically occurs when the thickness of the restrainer tube's wall is smaller than the cross-sectional area of the core plate or its width. In this study, a parametric investigation for BRBs with different formations has been performed to verify the effect of the design parameters such as different core section profiles, restraining member width to thickness ratio and relative cross-sectional area of the core to restrainer, on buckling load evaluation. The proposed BRB investigation results have also been presented and compared to past BRB researches with a plate profile as the core section, and the advantages and disadvantages of this configuration have been discussed, and it is concluded that BRBs with tubular core section exhibit a better seismic performance than the ones with a plate core profile.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.780-787
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• 2019

As a carbon-free, green growth alternative, internal and external interest in hydrogen energy and technology is growing. Hydrogen was added to co-axial methane, methane-propane, and methane-propane-ethane diffusion flames, which are the main ingredients of LNG, to evaluate its effect on flame formation and combustion products. The variation in combustion products produced by adding hydrogen gradually to diffusion pyrolysis at room temperature and normal pressure conditions was observed experimentally by using a gas analyzer, and the shape of diffusion pyrolysis was observed step by step using a digital camera. The experimental results showed that the production volume of nitrogen oxides tended to increase and became close to linear as hydrogen was added to the diffusion pyrotechnic. This is because the relatively high temperature of heat insulation and fast combustion speed of hydrogen facilitated the production of thermal NOx. On the other hand, CO2 production tended to decrease as hydrogen was added to reduce the overall carbon ratio contained in the mixed diffusion flame of methane, methane-propane, and methane-ethane-propane. This means that the mixed fuel use of LNG-hydrogen in ships may potentially reduce emissions of CO2, a greenhouse gas.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.6
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• pp.17-27
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• 2014

Wild boars are one of the major wild life animals of which the number has increased a lot because there has been any predator and/or competitor in the Korean ecosystem. The increase of their number was a cause damaging crops in farm lands during the growing season in South Korea. This study was done to recognize the spatial pattern of farm lands damaged by wild boars. Totally 2,342 farms were known damaged by wild boars in 2012, and used to statistically analyze the perspectives of the farm land damages by wild boars in ArcMap v. 9.3. Damages by wild boars frequently happened in the western part of Gyeongnam Province including Jinju city, Tongyoung city and Namhae county. Most farm lands damaged were located nearby large mountains in this area. It might cause the number of wild boars increased in this area, which could finally stimulate the increase of farm land damaged by the species. Farm land damages by wild boars were also coincident with the preference of wild boars on their food. They preferred crops (e.g., sweet potato and corn) in uplands and rice paddies and orchards. The reason of their preference on rice, upland crops and fruits was related to the efficiency of their getting much more energy in a unit area. Another reason for the species to come into a rice paddy would be that they enjoy mud bath in there for scraping off parasites such as ticks and lice. Wild boars were seemed much overcrowded during the period from July to October when most of crops and fruits get ripen. About three-quarters of total farm land damages happened in this period. This analysis also said that 1,915 fields (81.8% of total targets) appeared within the 100-meter buffer from boundaries of mountain areas. This meant that wild boars were more sensitive to the anthropogenic land uses than we expected. They seemed to conservatively try their feeding activities in farm lands with paying attention to the human activity.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.225-236
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• 2016

Objectives: Nanomaterials have been used in various fields. As use of nanoproducts is increasing, workers dealing with nanomaterials are also gradually increasing. Exposure assessments for nanomaterials have been carried out for protection of worker's health in workplace. Exposure studies were mainly focused on manufacturing processes, but these studies on after-treatment processes such as refinement, weighing, and packing were insufficient. So, we investigated exposure characteristics of particles during after-treatment processes of $Al_2O_3$ fibers and Ni powders. Methods: Mass-production of Ni powder process was carried out in enclosed capture-type canopy hood. In a developing stage, $Al_2O_3$ was handled with a local ventilation unit. Exposure characteristics of particles were investigated for $Al_2O_3$ fiber and Ni powder processes during the periods of 10:00 to 16:00, 20 May 2014 and 13:00 to 16:00, 21 May 2014, respectively. Three real-time aerosol instruments were utilized in exposure assessment. A scanning mobility particle sizer(SMPS, nanoscan, model 3910, TSI) and an optical particle counter(OPC, portable aerosol spectrometer, model 1.109, Grimm) were used to determine the particle size distribution in the size range of 10-420 nm and $0.25-32{\mu}m$, respectively. In addition, a nanoparticle aerosol monitor(NAM, model 9000, TSI) was used to measure lung-deposited nanoparticle surface area. Membrane filters(isopore membrane filter, pore size of 100 nm) were also used for air sampling for the FE-SEM(model S-5000H, Hitachi) analysis using a personal sampling pump(model GilAir Plus by 2.5 L/min, Gilian). Conclusions: For Ni powder after-treatment process, only 27% increase in particle concentration was found during the process. However, for $Al_2O_3$ fiber after-treatment process, significant exposure(1.56-3.34 times) was observed during the process.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.75-80
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• 2011

Purpose: Europe and U.S use multi-bed therapy rooms. Hereupon, this study aims to examine the safety when current one-bed therapy rooms in Seoul National University Hospital is changed into two-bed ones. Materials and Methods: This study evaluated external exposure by gamma radiation emitted from other patients and internal and external exposure caused by pollutions from other patients in case that Seoul National University Hospital installs a shielding wall between beds in existing therapy rooms. Results: When internal and external exposure was evaluated to evaluate safety of two-bed hospital rooms, 'isolation amount of patients' 5mSv exposure or below is received according to the Atomic Energy Act. Conclusion: With the increasing number of patients with thyoid cancer, patients using therapy rooms are on the rise. Therefore, improving one-person therapy rooms to two-person ones in line with international trend would increase cost reduction and management efficiency, and patients' alienation and isolation can be reduced to increase healing effects.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.355-363
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• 2015

Advancement in the medical field provides an opportunity for the development of medical equipment and also enable accurate diagnosis for the inspection and the treatment of diseases. The aging of equipment due to the frequent operation produce uncertainty in the patient exposure dose, so a quality control was implemented by establishing a safety management system on a regular basis. The x-ray tube voltage (kVp), which is directly involved in the patient exposure dose and the life of the equipment, needs periodic performance for the quality control, but it has a limitation due to the time and the cost. In this study, we proposed a new method for measuring the kVp with ease by using the Y and Cu to solve the problem of the time and cost. We also evaluated the usefulness and the effectiveness of the new method and its accuracy through the kVp measurement. After securing the condition, the amount of the tube current and evaluating the usefulness and effectiveness of kVp measured using Y and Cu. The density range used was at 0.5-1.0, kVp was in the range of ${\pm}10%$, then, we recorded the change in concentration as % of Y and Cu. This experiment showed that when Cu and Y was at 75 kVp, concentration was the same, and when the kVp was changed to 65 ~ 85 %, a gradual increase in concentration to 85 ~ 110 % was noted.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.2
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• pp.19-29
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• 2012

Numerous studies suggested that fish assemblage structure reflects the status of stream ecosystems. The status of streams integrity, including various trophic levels, water quality and habitat degradation, can be assessed by fish assemblages. In this study, we investigated the relationships between fish assemblages and streamline geometry of streams. Previous studies suggested that geomorphologic parameter can be a critical factor of permeability between adjacent two systems. From a landscape ecological perspective, edges may partially control the flow rate of energy between two adjacent systems. Thus, the Streamline geometry can be a geomorphologic parameter that exhibits the integrity of stream. We selected the Nakdong river for study areas, which is one of major rivers and the longest (525 km) River in South Korea. We used the revised IBI representing overall ecological characteristics of Korean fish assemblages and eight sub-assessment criteria of IBI, collected from 82 sampling sites in the Nakdong River. For calculating the Streamline geometry, we measured fractal dimension index that generally used in biology, ecology and landscape ecology. We used the digital land-use/land-cover map and generated a 1-km buffer for each sampling site and refined the shape of the Streamlines. Pearson correlation analyses were performed between Streamline geometry and IBI and sub-assessment criteria of IBI. The results show that IBI and eight sub-assessments of fish are significantly correlated with geometry of Streamline. The fractal dimension of Streamline geometry were related with IBI (r = 0.48) and six sub-assessments of IBI, including total number of native fish and native species, the number of riffle benthic species, sensitive species, tolerant species and native insectivore. Especially, the number of tolerant species(r = -0.52) and native insectivore(r = 0.52) show strong correlation with geometry of Streamline. These results indicate that lower Streamline geometry can result in poor fish assemblages, while higher geometry of Streamline can enhance fish assemblages by potentially supplying insects and better habitat conditions. We expect the results of our study to be useful for stream restoration and management. However, we see the necessity of study investigating the mechanisms how Streamline geometry affect fish assemblages.

• Clean Technology
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• v.20 no.4
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• pp.439-448
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• 2014

The potential mitigation of greenhouse gas (GHG) is studied in the Pohang steel industrial complex (PHSIC). The total GHG emission in 2010 is estimated to be in the range from 4,174,000 to 4,574,000 $tCO_2-eq$ in PHSIC. To meet the target proposed by the government, it is needed to reduce 552,000 $tCO_2-eq$ at minium by 2020. To estimate the potential amount of GHG reduction, the technologies used in the voluntary carbon reduction projects are applied to 51 companies which are subject to GHG target management. From the viewpoint of technological availability and payback period, the fuel conversion and waste heat recovery have an advantage in the short term with a possibility to reduce 160,000 $tCO_2-eq$. In the mid term, the thermal technologies in steel and iron industry have the potential to cut 229,000 $tCO_2-eq$, while the electrical technologies have the potential of 125,000 $tCO_2-eq$ reduction. The gap between the target GHG mitigation and potential reduction using the short and mid term technologies is about 38,000 $tCO_2-eq$, which should be compensated by the fundamental process innovation and the implementation of the most cutting-edge technologies including renewable energy.

• Korean Journal of Community Nutrition
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• v.22 no.5
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• pp.441-455
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• 2017

Objectives: The purpose of this study is to describe beverage patterns among healthy Korean adults and investigate their association with prevalence and components of metabolic syndrome. Methods: Subjects consisted of 6,927 Korean adults, aged 19-64 years in the $6^{th}$ Korea National Health and Nutrition Examination Survey (KNHANES, 2013-2015). Beverages were regrouped into twelve groups based on food codes and beverage intake (g/day) was assessed by 24-hour recall. Factor analysis was used to obtain beverage patterns. Waist circumference and body mass index (BMI) were used as anthropometric data; fasting blood glucose, triglyceride, high density lipoprotein (HDL), and blood pressure were used as biochemical indicators. The odds ratio (OR) for prevalence of metabolic syndrome and components of metabolic syndrome was assessed using logistic regression analysis. Results: Three beverage patterns were identified using factor analysis: 1) carbonated soft drinks 2) coffee (without added sugar or powdered creamer), and 3) alcoholic beverages. Subjects with high scores for the carbonated soft drink and coffee without added sugar or powdered creamer patterns were younger and subjects with high scores for the alcoholic beverage pattern were older. There were significant differences in gender distribution in all three beverage patterns, with men more likely to have high scores for carbonated soft drink and alcoholic beverage patterns. On the other hand, women were more likely to have higher scores for coffee without added sugar or powdered creamer pattern. Within each pattern, there were significant differences in sociodemographic and lifestyle characteristics such as education, household income, frequency of eating out, and smoking status according to the quartile of pattern scores. Alcoholic beverages and carbonated soft drinks patterns were associated with an increased levels of metabolic syndrome components, but coffee without added sugar or powdered creamer was not associated with any of metabolic syndrome components in healthy Korean adults after adjusting for age, sex, education, BMI, weight management, household income, smoking status, frequency of eating out, and energy intake. Conclusions: Alcoholic beverages and carbonated soft drinks patterns are associated with increased levels of metabolic syndrome components while coffee without added sugar or powdered creamer pattern is not associated with any of metabolic syndrome components in healthy Korean adults.