• Ocean Systems Engineering
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• v.13 no.2
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• pp.97-121
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• 2023

Through-the-thickness stress distribution in a tubular member has a profound effect on the fatigue behavior of tubular joints commonly found in steel offshore structures. This stress distribution can be characterized by the degree of bending (DoB). Although multi-planar joints are an intrinsic feature of offshore tubular structures and the multi-planarity usually has a considerable effect on the DoB values at the brace-to-chord intersection, few investigations have been reported on the DoB in multi-planar joints due to the complexity of the problem and high cost involved. In the present research, data extracted from the stress analysis of 243 finite element (FE) models, verified based on available parametric equations, was used to study the effects of geometrical parameters on the DoB values in two-planar tubular DYT-joints. Parametric FE study was followed by a set of nonlinear regression analyses to develop six new DoB parametric equations for the fatigue analysis and design of axially loaded two-planar DYT-joints.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.709-711
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• 2022

ICT 기술의 빠른 발전과 함께 Internet of Things (IoT) 환경에서의 Internet Protocol (IP) 카메라의 사용률이 증가하면서, IP 카메라에 대한 개인정보 이슈와 제품의 보안성 검토 관련 소비자의 개인정보 유출 우려가 증가하고 있다. 본 논문에서는, IP 카메라에 대한 4개 종류의 Denial of Service (DoS) 공격을 통해 IP 카메라 이상 반응을 확인했다. 또한, 이 과정에서 수집한 공격 패킷 데이터를 기반으로, DoS 공격을 탐지하는 간단한 피쳐 구성과 머신러닝 모델을 제안하였다. 최종적으로, DoS 공격을 통해 실제 IP 카메라에 대한 가용성 테스트를 수행하였으며 머신러닝 알고리즘 4개 Decision Tree, Random Forest, Multilayer Perceptron, SVM에서의 DoS 공격 탐지 성능을 비교하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.2
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• pp.275-280
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• 2015

This study investigated intake frequency and opinions regarding native local foods in school foodservice and compared eating status between students in Gyeongsang-do and Jeolla-do. Questionnaires were distributed to 300 students at elementary schools located in Gyeongsang-do and Jeolla-do. The results of this study were as follows. First, intake frequencies of Gyeongsang-do-native local foods by students in Gyeongsang-do was significantly higher than compared to students in Jeolla-do (P<0.01). Second, there was no significant difference in concern for native local foods between students in Gyeongsang-do and students in Jeolla-do, although opinions regarding native local foods in school foodservice by students in Gyeongsang-do were higher compared to students in Jeolla-do (P<0.01). In conclusion, there was a regional difference in terms of intake frequency of Gyeongsang-do-native local foods, whereas there was no regional difference in terms of intake frequency of Jeolla-do-native local food. Students in Gyeongsang-do showed more positive attitudes regarding native local foods in school foodservice than students in Jeolla-do. This result implies that regional differences between Gyeongsang-do and Jeolla-do regarding native local foods should be removed. In order to develop native local foods, it will be necessary to develop a program to actively apply native local foods in school foodservice and provide more chances for elementary school students to experience various native local foods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.2
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• pp.146-153
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• 2009

This study was conducted to examine the effects of fruits and stems of Opuntia ficus-indica var. saboten Makino on water intake, feed intake, body weight, blood glucose level and glucose tolerance in streptozotocin (STZ)-induced diabetic rats. Forty Sprague-Dawley male rats were divided into non-diabetic control (NC), diabetic control (DC), 8% Opuntia fruit (DOF), 5% Opuntia stem (DO-5) and 10% Opuntia stem (DO-10) groups. Fruits and stems of Opuntia ficus-indica were freeze-dried and ground before use in the experiment. Animals were fed experimental diet for 3 weeks. DOF, DO-5 and DO-10 groups showed lower water and feed intake as well as less body weight loss than DC group. The fasting blood glucose levels were 100 mg/dL for NC and 379 mg/dL for DC. Fasting glucose level of DOF was a significantly low level of 28% (p<0.05), whereas DO-5 and DO-10 had a decrease of 5% and 9% compared to DC. As for the glucose tolerance test, the highest blood glucose levels for NC and DC-10 group were observed at 30 minutes after glucose injection while those of DOF and DO-5 groups were after 60 minutes. DOF and DO-5 plasma insulin level improved. Plasma total cholesterol, triglyceride, non-esterified fatty acid (NEFA) and LDL-cholesterol concentrations were also lower in DOF, DO-5 and DO-10 groups, although HDL-cholesterol level was only slightly affected by experimental diets compared to DC. These results suggest that the feeding of Opuntia ficus-indica fruits and stems improved blood glucose and lipid metabolism in STZ-induced diabetic rats.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.355-361
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• 2006

In this study, effects of influent C/N(COD/Nitrate) ratio and dissolved oxygen(DO) concentration on biological nitrate removal from groundwater were investigated in the fixed-type biofilter. Influent nitrate of 30 mg/L was removed completely by biological denitrification at the C/N ratio of 10 and 4.0, while residual nitrate of 5 mg/L occurred at the C/N ratio of 2.0, which resulted from deficiency of organic electron donor. Furthermore, nitrite was accumulated up to about 5 mg/L as the C/N ratio decreased to 2.0. Increase in DO concentration also inhibited denitrification activity at the relatively high C/N ratio of 5.0, which decreased the nitrate removal efficiency. Although the influent DO concentration was reduced as low as 0.3 mg/L using sodium sulfite($Na_2SO_3$), effluent nitrite was up to 3.6 mg/L. On the other hand, nitrate was completely removed without detection of nitrite at the DO concentration of 0.3 mg/L using nitrogen gas($N_2$) sparging. The organic matter for denitrification in biofilter were in the range from 3.0 to $3.5gSCOD/g{NO_3}^--N$, while utilized these values increased at the high DO concentration of 5.5 mg/L. In addition to the high DO concentration and the low influent C/N ratio, DO control by chemical such as sodium sulfite affected on biological denitrification, which resulted in the reduction of nitrate removal efficiency and nitrite build-up in a biofilter.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.70.2-70
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• 2002

• Journal of Korean Society of Forest Science
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• v.99 no.5
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• pp.698-705
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• 2010

The concentration of monoterpenes (12 species) was measured from spring to fall in 2008 in ambient air at six different forests located in the southern parts of Korea. Sampling - using a Solid Adsorption Tube - was conducted at 2-hour-interval a day (24 hours) of each season. The highest annual average concentration of total monoterpene was 0.715 ppbv, which occurred at Mt. Baega. ${\alpha}$-Pinene, sabinene and ${\beta}$-pinene were the most abundant compounds throughout the sampling periods and areas. The concentrations of monoterpene were higher in spring than in any other seasons. The compositions and concentrations of monoterpene displayed a distinct pattern by area. Most of monoterpenes had diurnal variations with higher concentrations during the daytime, and lower during the nighttime. This may be due to the fact that the amount of monoterpenes emitted increases at elevated ambient temperatures and increased sunlight intensity. The results of this study showed that each area had distinct monoterpene compositions, which depended on the tree species, topography and local climate at each area.

• Journal of environmental and Sanitary engineering
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• v.20 no.2 s.56
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• pp.39-46
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• 2005

This study was Performed to survey and evaluate the contents of Plasticizers such as DEP(diethyl phthalate), DPrP(di-n-Phthalate), DBP(di-n-butyl Phthalate), DPP(di-n-pentyl Phthalate), DCHP(dicyclohexyl phthalate), BBP (butylbenzyl phthalate), DEHP(di-(2-ethylhexyl) phthalate) and DEHA(di-(2-ethylheryl) adipate), which are suspected as endocrine disruptors, in food and drug PVC packaging. Tested samples were 5 food wraps, 35 food containers, 40 food and drug packages(type of tablet and capsule) in Gyeonggi-Do area. The contents of DEHA in wrap were 188.9g/kg, 203.1g/kg, 238.4g/kg, 290.9g/kg and 308.3g/kg, respectively, while the other plasticizers were not detected. DEHP was used in 4 samples of food containers and DEHP contents were 4.7g/kg, 30.7g/kg, 35.8g/kg and 53.4g/kg, respectively. In food and drug packaging materials(type of tablet and capsule), the plasticizers were not detected.

• Journal of Environmental Health Sciences
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• v.44 no.2
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• pp.169-177
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• 2018

Objectives: The emission characteristics of aldehydes were investigated in five industries for the efficient management of aldehydes. Methods: Aldehydes and THC were measured from the stack and boundary of facilities. The relative concentrations and odor contribution of aldehydes were evaluated. Results: The concentrations of aldehydes in the asphalt manufacturing and printing industries were relatively high. Formaldehyde met emission limits for all facilities. According to the odor contribution analysis of aldehydes, i-valeraldehyde and butyraldehyde, which have a relatively low odor threshold value, were found to be the major odor-causing substances in the painting and textile processing industries. Conclusions: Among the aldehydes, the major emission compounds were formaldehyde in asphalt manufacturing, acetaldehyde in the paper manufacturing and textile processing industries, and butyraldehyde in the printing and painting industries. Therefore, to increase the effectiveness of aldehyde reduction, proper control devices need to be installed and operated according to the emission characteristics of aldehydes.

• Journal of Environmental Health Sciences
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• v.44 no.3
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• pp.244-249
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• 2018

Objectives: The purpose of this study was the investigation of bromide and bromate in drinking water of water supply plants, mineral springs and small water supply system located in northern area of Gyeonggi province. Methods: Analytical method was based on EPA 326.0 to use Postcolumn reaction (PCR). The instrument was 887 professional UV/VIS detector IC manufactured in Metrohm. Results: Bromate was detected at $0.5{\sim}2.4{\mu}g/L$ in tap water from 5 water supply plants. These plants were used as disinfection method for sodium hypochlorite and on-site chlorine that causes generate bromate as a by products even if not used ozone. Conclusions: The bromate was detected up to $2.5{\mu}g/Lin$ drinking water in northern Gyeonggi area that showed within $10{\mu}g/L$ for standard of tap water. However, the continuous monitoring of bromate is necessary in drinking water.