• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.376-389
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• 2022

Despite the consumption of disinfectants have been increased by COVID-19 pandemic, the fate of the chemicals in aquatic food webs are still unclear. In order to understand the trophic transfer of the chemicals, the concentration of disinfectants including six benzalkonium chloride (BACs) and five didecyldimethylammonium chlorides(DDACs) were measured at the Geum (2020), Han (2021), and Yeongsan River (2021), before and after rainfall. The highest concentration of ∑BACs (mainly C12 and C14) and ∑DDACs (mainly C10 and C14) were observed in the Han River, followed by Yeongsan River, Geum River Estuary, and Gapcheon. After rainfalls, both concentration and detection frequency were decreased in all sites. Although the BAC and DDAC seems to be accumulated in organisms, they were bio-diluted rather than magnified in the aquatic food web with the biomagnification factor(BMF) of less than 1, trophic magnification slope (TMS) from -0.236 to 0.001, and trophic magnification factor(TMF) from 0.85 to 1.01.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.352-359
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• 2022

Recently, with the development of genetic technology, interest in environmental DNA (eDNA) to study biodiversity according to molecular biological approaches is increasing. Environmental DNA has many advantages over traditional research methods for biological communities distributed in the environment but highly depends on the established base sequence database. This study conducted a comprehensive analysis of the habitat status and classification at the genus level, which is mainly used in eDNA (12S rRNA, 16S rRNA, 18S rRNA, COI, and CYTB), focusing on Korean registration taxon groups (phytoplankton, zooplankton, macroinvertebrates, and fish). As a result, phytoplankton and zooplankton showed the highest taxa proportion in 18S rRNA, and macroinvertebrates observed the highest ratio in the nucleotide sequence database in COI. In fish, all genes except 18S rRNA showed a high taxon ratio. Based on the Korean registration taxon group, the gene construction of the top 20 genera according to bio density observed that most of the phytoplankton were registered in 18S rRNA, and the most significant number of COI nucleotide sequences were established in macroinvertebrates. In addition, it was confirmed that there is a nucleotide sequence for the top 20 genera in 12S rRNA, 16S rRNA, and CYTB in fish. These results provided comprehensive information on the genes suitable for eDNA research for each taxon group.

• Korean Journal of Environmental Biology
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• v.41 no.2
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• pp.126-137
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• 2023

Paddy fields provide important habitats for biodiversity conservation within the agricultural ecosystem. Their importance is gradually increasing as their ecological value is better understood. Benthic macroinvertebrates dominate paddy fields. They play an essential role in maintaining the biodiversity of paddy ecosystems. This study aimed to analyze characteristics of benthic macroinvertebrate communities and main environmental factors affecting the distribution of golden apple snails (Pomacea canaliculata). Results showed that the diversity index (H') of the benthic macroinvertebrate community was the highest at the Sangju site (St. 12) but the lowest at the Sancheong site (St. 18). Total Dissolved Solids (TDS), salinity, and Electrical Conductivity (EC) values were the highest in Gimhae and Yeongam based on Canonical Correspondence Analysis (CCA). Numbers of P. canaliculata (m-2) were relatively low in Gunsan and Iksan where water temperatures were high. Therefore, changes in geographical characteristics and environmental factors might affect the distribution of P. canaliculata and characteristics of benthic macroinvertebrate communities. Results of this study can be used as primary data for biodiversity conservation and ecosystem service evaluation in agroecosystems.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.51-57
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• 2023

Because of the global pollution caused by plastic disposal, demand for eco-friendly transformation in the packaging industry is increased. As part of that, the utilization of polylactic acid (PLA) as a food packaging material is increased. However, it is necessary to improve the crystallinity of PLA by adding nucleating agents or to improve the modulus by adding fillers because of the excessive brittleness of the PLA matrix. Thus, the cellulose nanofiber (CNF) was fabricated and dried to obtain a powder form and applied to the CNF/PLA nanocomposite. The effect of CNF on the morphological, thermal, rheological, and dynamic mechanical properties of the composite was analyzed. We can confirm the impregnated CNF particle in the PLA matrix through the field emission scanning electron microscope (FE-SEM). Differential scanning calorimetry (DSC) analysis showed that the crystallinity of not annealed CNF/PLA nanocomposite was increased approximately 2 and 4 times in the 1st and 2nd cycle, respectively, with the shift to lower temperature of cold crystallization temperature (T_cc) in the 2nd cycle. Moreover, the crystallinity of annealed CNF/PLA nanocomposite increased by 13.4%, and shifted T_cc was confirmed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1B
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• pp.101-105
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• 2010

Sunflower (Sunking4505) and Rape (Sunmang) are oil-seeds containing high oleic acid, and these are used for the production materials of bio-diesel and applying for phytoremediation. The effect of cadmium on germination rate and the growth of the plants is evaluated. Object seeds were placed in Cd (0, 1.5, 4, 12, 30, 60, 100, 150, 300, 500 mg/L) solutions for seven days, and germination rate, root length, shoot length, seedling length, and dry weight were observed. $IC_{50}$, seedling vigor index, and tolerance indices were computed, and data were statistically analyzed by Analysis of Variance (ANOVA). Germination rate as well as root, shoot, and seedling length decreased as the cadmium concentration increased except dry weight. The $IC_{50}$ of sunflower and rape are 112 and 10 mg-Cd/L, respectively. Only one of the sunflower seeds is germinated at 500 mg-Cd/L whereas rape seeds are not germinated more than 150 mg-Cd/L solution. Root has higher cadmium sensitivity than shoot, and sunflower has higher germination rate, growth, and seedling vigor index than rape. In case of tolerance indices, sunflower has lower value than rape at relatively low concentration, but has higher value at high concentration.

• 재활복지
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• v.15 no.2
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• pp.147-173
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• 2011

The purpose of this study was to develop a stuttering therapy device to aid in stutter therapy. The research method used for this study was as follows: First, the stuttering therapy device based on analysis of the prolonged speech method used at home and abroad was designed to achieve the goal of research. Second, the stuttering therapy device was to be developed to maintain a vocalization state, to use bio-feedback visualization, to have enough inspiration, to use Korean language in this device, and to use transfer and maintenance training in daily life. Third, the stuttering therapy device effectiveness was to be verified through use in clinical cases. The results of subjects receiving speech therapy and using the breathing control prolonged speech device and SI(stuttering Interview) evaluation programs for 3 months were as follows: For subject A, the stuttered word rate was reduced from 3.20 SW/M to 0.5 SW/M. For subject B, the stuttered word rate was reduced from 1.90 SW/M to 0.75 SW/M. For subject C, the stuttered word rate was reduced from 3.37 SW/M to 0.34 SW/M. For Subject D, the stuttered word rate was reduced from 0.51 SW/M to 0 SW/M. Follow-up evaluations verified the effectiveness of how the stuttering therapy device can reduce subjects' SW/M.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.89-98
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• 2019

The aim of this study was to evaluate the change of phenolic compounds after bordeaux mixture treatment on Cheorwon onion. Onion is a perennial plant belonging to the lily family. It is native to Persia of Southwest Asia. It is cultivated much in the temperate regions of the world. Onion is a good name for the 'Okchong' to drop blood cholesterol and cardiovascular blood flow to increase the prevention of adult diseases. Cheorwon area is inland, but it has high continental climate due to its high altitude. After the treatment with bordeaux mixture, the weight, width and plant height of the onion were affected to some extent. In the phenolic compounds, caffeic acid, ferulic acid, rutin, and kaempferol except benzoic acid, p-coumaric acid and quercetin were similar to or less than the control. Therefore, it was concluded that the treatment with bordeaux mixture had some effect on onion growth and phenolic compound contents.

• Journal of Naturopathy
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• v.7 no.2
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• pp.51-62
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• 2018

Purpose: The purpose of this study was to investigate the changes of stress and cumulative stress in 49 people and the changes of job stress, socio-psychological stress and anxiety relief levels by conducting a survey of 85 people after Gyorae forest bathing. Methods: The level of stress was measured using the uBioMacpa, and questionnaire was conducted to derive the data. Results: In the stress level after the forest bath, the control group showed no significant and the experimental group showed a significant decrease in the bathing (p<.043). In the cumulative stress change, the control group showed no significant difference after the bathing, but experimental group decreased significantly (p<.02), and in the variance analysis, there was a significant difference between the groups, and also between the group and the before and after tests (p<.002). In the questionnaire about job stress, there was no significant difference in physical environment and job demand. Overall, in the case of job stress, there was a significant decrease (p<.001). Job autonomy, relationship conflict, organizational unfairness, inadequate compensation, and workplace culture also had a significant decrease in stress (p<.001). The social psychological stress was significantly decreased after bathing (p<.001). The state anxiety decreased significantly (p<.001) after forest bathing. Conclusions: After the forest bathing in the Gyorae forest, the stress and anxiety are both reduced and significant, providing basic information that is very helpful as a natural healing place for stress relief.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.383-394
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• 2023

In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m²), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10^-4, 2.01×10^-4, and 6.85×10^-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10^-2, 1.63, and 2.59×10^-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

• Journal of the Korea Society for Simulation
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• v.32 no.4
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• pp.77-84
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• 2023

In the agricultural sector, power sources are being developed that use alternative energy sources such as electric tractors and hydrogen tractors, away from internal combustion engine tractors. As parts such as engines and transmissions used in conventional internal combustion engine tractors are replaced with motors and batteries, the center of gravity changes, and thus the risk of rollover should be considered. The purpose of this study is to analyze the overturn angle of the main parts of the electric tractor through dynamic simulation to minimize the overturn accident and to derive the optimal arrangement of parts to improve stability. A total of nine dynamics simulations were conducted by designing three components of the PTO motor, drive motor and the battery pack, and three factors of the arrangement method. As a result of the experiment, it was confirmed that Type3 Level3, in which the drive motor and the PTO motor are located at the front and rear of the tractor, and two battery packs are located in the middle of the tractor, has a high rollover angle. As a result of this study, the stability increased as the center of gravity was placed backward and located below. Future research needs to be done to find the optimal location of parts considering their performance and placement efficiency.