• Journal of Environmental Impact Assessment
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• v.22 no.2
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• pp.135-145
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• 2013

The recycling of coal bottom ash generated from coal power plants in Korea has been limited due to heterogenous characteristics of the materials. The most common management option for the ash is disposal in landfills (i.e. ash pond) near ocean. The presence of large coarse and fine materials in the ash has prompted the desire to beneficially use it in an application such as fill materials. Prior to reuse application as fill materials, the potential risks to the environment must be assessed with regard to the impacts. In this study, a total of nine test cells with bottom ash samples collected from pretreated bottom ash piles and coal ash pond in a coal-fired power plant were constructed and operated under the field conditions to evaluate the leachability over a period of 210 days. Leachate samples from the test cells were analyzed for a number of chemical parameters (e.g., pH, salinity, electrical conductance, anions, and metals). The concentrations of chemicals detected in the leachate were compared to appropriate standards (drinking water standard) with dilution attenuation factor, if possible, to assess potential leaching risks to the surrounding area. Based on the leachate analysis, most of the samples showed slightly high pH values for the coal ash contained test cells, and contained several ions such as sodium, potassium, calcium, magnesium, chloride, sulfate, and nitrate in relatively large quantities. Three elements (aluminum, boron, and barium) were commonly detected above their respective detection limits in a number of leachate samples, especially in the early leaching period of time. The results of the test cell study indicate that the pollutants in the leachate from the coal ash test cells were not of a major concern in terms of leaching risk to surface water and groundwater under field conditions as fill materials. However, care must be taken in extending these results to actual applications because the results presented in this study are based on the limited field test settings and time frame. Structural characteristics and analysis for coal bottom ash may be warranted to apply the materials to actual field conditions.

• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.564-577
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• 2017

We investigated whether external environmental factors acted as a trigger for flowering in the draft bamboo (Sasa borealis (Hack.) Makino) blooming area of Mt. Baekwoon located in Gwangyang, South Jeolla Province. We then considered the cause for flowering, flowering patterns and life history strategies of the draft bamboo based on the investigation. There were no differences in soil, physical conditions, and light amount between the draft bamboo flowering and non-flowering areas. The precipitation and temperature of the areas in Korea and Japan where it blossomed from 2014 to 2017 were similar to the normal year values (for the past 30 years). Moreover, most of the draft bamboo died after flowering on a large scale, but some did not, or some culms were developed again. In other words, the draft bamboo bloomed simultaneously regardless of external environmental factors, and most of the culms were dead, but some were left alive. Therefore, it is considered that the flowering is triggered by the specific genes (referred as to clock genes) expressed periodically by a biological clock rather than the external environmental factors. Meanwhile, the draft bamboos generally bloom on a large scale by synchronizing with other ones in the distance but may also bloom several times separately on a small scale. It may be a kind of an insurance system established to disperse the risk of failed sexual propagation when flowering once in a lifetime. The results reveal that the long-period monocarpy of the draft bamboo has been strengthened to optimize the sexual propagation to overcome the increased environmental instability caused by the expansion of distribution of tropical bamboos and bamboo species to the temperate regions.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.4
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• pp.361-370
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• 2017

Previous reports have suggested that physical and psychological stresses may trigger fibromyalgia (FM). Stress is an important risk factor in the development of depression and memory impairments. Antidepressants have been used to prevent stress-induced abnormal pain sensation. Among various antidepressants, tianeptine has been reported to be able to prevent neurodegeneration due to chronic stress and reverse decreases in hippocampal volume. To assess the possible effect of tianeptine on FM symptoms, we constructed a FM animal model induced by restraint stress with intermittent cold stress. All mice underwent nociceptive assays using electronic von Frey anesthesiometer and Hargreaves equipment. To assess the relationship between tianeptine and expression levels of brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), and phosphorylated cAMP response element-binding protein (p-CREB), western blotting and immunohistochemistry analyses were performed. In behavioral analysis, nociception tests showed that pain threshold was significantly decreased in the FM group compared to that in the control group. Western blot and immunohistochemical analyses of medial prefrontal cortex (mPFC) and hippocampus showed downregulation of BDNF and p-CREB proteins in the FM group compared to the control group. However, tianeptine recovered these changes in behavioral tests and protein level. Therefore, this FM animal model might be useful for investigating mechanisms linking BDNF-CREB pathway and pain. Our results suggest that tianeptine might potentially have therapeutic efficacy for FM.

• Analytical Science and Technology
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• v.32 no.6
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• pp.252-261
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• 2019

Pyrrolizidine alkaloids (PAs) are a group of secondary metabolites that are produced by plants all over the world as a defense mechanism against herbivores. To date, over 660 PAs have been identified from more than 6,000 plant species that have been reported to be widely present in plants belonging to Asteraceae, Boraginaceae, and Fabaceae. This study describes an analytical method based on UPLC-MS/MS for the quantitation of 7 pyrrolizidine alkaloids (Lycopsamine, Echimidine, Retrorsine, Retrorsine N-oxide, Senecionine, Heliotrine, and Trichodesmine) in honey, and was applied to 84 honey samples for validation. Quantitation was performed based on a matrix-matched calibration to compensate for the matrix effect on the electrospray ionization. Good linear calibrations were obtained for all 7 PAs in the spiked honey samples (2.575-202.14 ㎍/kg; R² ≥ 0.998). The extraction recoveries for most of the PAs in the honey samples were in the range of 81 %-108 %. The analysis showed that 6 of the 84 honey samples were contaminated by the PAs with the mean total sum of PAs being 47.19 ㎍/kg, and the concentrations of the PAs were observed to be in the range of 1.76-202.1 ㎍/kg. The retronecine type compounds (Echimidine, Lycopsamine) were the most frequently found PAs in honey. These data provide useful information for the assessment of human risk posed by the consumption of honey contaminated PAs.

• The korean journal of orthodontics
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• v.33 no.5 s.100
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• pp.381-389
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• 2003

Mutans streptococci is the major causative factor in dental caries. Especially, orthodontic patients with fixed appliance are a risk group for dental caries. Because fixed appliances attached on teeth may change the environment of dental plaque, the enamel decalcification or dental caries around the bracket and band is a major side effect of orthodontic treatmet. The aim of this study was to search plant extracts that have antimicrobial effect on mutans streptococci. Seed-extract of Casia torn were prepared with ethanol and CHMC-2032, the leaf-extracts from Camellia sinensis extract, was obtained extract, 2 type strains and 20 clinical isolates of mutans streptococci isolated from the interface between orthodontic brackets and tooth surfaces in the orthodontic patients were used in this study. The minimal inhibitory concentration of CHMC-2032 was 5mg/ml on the S. mutans KCTC 3065, S. sobrinus KCTC 3088, and 8 clinical isolates of S. sobrinus. However, there was no antibacterial effect of seed-extract of C. tora on mutans streptococci. These data suggest that green tea nay be more effective than the tea Prepared from C tora In the prevention of enamel decalcification or dental caries around brackets.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.1
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• pp.25-31
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• 2017

The objective of this study is to find the failure factors of venture companies. We analyze 210 troubled venture companies, all of which have been under guarantee from the Korea Technology Finance Corporation over the last three years. Methods of analysis for failure factors are as follows. First, we categorize the failure factors into the four different types based on growth and profitability indicators in the financial statements of targeted venture companies. Then we analyzed the failure factors of the subject companies based on the troubled guarantee reports made by the Korea Technology Finance Corporation. If a venture company under its guarantee program falls into insolvency, the Korea Technology Finance Corporation make the troubled guarantee report to find out the failure factors and evaluate the recovery potentials. We identify 374 failure factors of venture companies through the analysis. The most prominent among them are deteriorating of business environments (79 factors) and decreasing or withdrawing orders from major suppliers (54 factors) due to bankruptcies or change in business plans. They are followed by slowing collection of accounts receivable (31 factors), dropping or frozen product price (24 factors) due to intensifying competition and escalating pressures from major suppliers, rising raw material costs both at home and abroad (21 factors). In addition, the nuclear power plant disaster in Japan, shut-down of the Kaesong Industrial Complex and subsequent lawsuits, delay in technology development projects, high cost-low efficiency management structure, etc., are also revealed as new factors causing trouble for venture companies.

• Journal of the Korean Society of Safety
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• v.21 no.4 s.76
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• pp.127-133
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• 2006

The major purpose of this paper to identify safety climate practices, and to find the affecting variables that influence to the difference in the level of safety climate between plants and employees. And this paper attempted to find the interventions for improving safety climate in the chemical plants. The questionnaires were developed from literature review, especially made by HSE(Health and Safety Executive) in the UK and distributed to managers and workers. The frequency analysis was applied for identifying the level of safety climate. The affecting variables(plant size, accident occurrence, accident experience, injury experience and severity, and length of employment) are tested through analysis of variance(ANOVA). The results of frequency analysis showed that both managers and workers recorded generally high level of safety climate, and the major underlying problems are inadequate H&S procedures/rules, pressure for production, and rule breaking. According to the outcomes of ANOVA, the variable 'length of employment' is the only variable which makes the level of safety climate different. From the survey of safety climate practice, this study finds the level of safety climate and three major underlying problems in safety climate factors of the responded plants, and presents two interventions for improving safety performance. Despite of these outcomes, the applied factors are remained questionable for reflecting as the best ones for identifying safety climate in the chemical industry. In addition, the bias caused by self-report exist in the reliability of the response, and the equivalent size of respondents.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.207-218
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• 2008

The impacts of planted transgenic rice varieties on bacterial communities in paddy soils were monitored using both cultivation and molecular methods. The rice field plot consisted of eighteen subplots planted with two genetically modified (GM) rice and four non-GM rice plants in three replicates. Analysis with denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes revealed that the bacterial community structures were quite similar to each other in a given month, suggesting that there were no significant differences in bacterial communities between GM and non-GM rice soils. The bacterial community structures appeared to be generally stable with the seasons, as shown by a slight variation of microbial population levels and DGGE banding patterns over the year. Comparison analysis of 16S rDNA clone libraries constructed from soil bacterial DNA showed that there were no significant differences between GM and non-GM soil libraries but revealed seasonal differences of phyla distribution between August and December. The composition profile of phospholipid fatty acids (PLFA) between GM and non-GM soils also was not significantly different to each other. When soil DNAs were analyzed with PCR by using primers for the bar gene, which was introduced into GM rice, positive DNA bands were found in October and December soils. However, no bar gene sequence was detected in PCR analysis with DNAs extracted from both cultured and uncultured soil bacterial fractions. The result of this study suggested that, in spite of seasonal variations of bacterial communities and persistence of the bar gene, the bacterial communities of the experimental rice field were not significantly affected by cultivation of GM rice varieties.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.352-352
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• 2017

Recently, the South Korean government encourages the cultivation of upland crops in the paddy field to maintain an adequate level of rice production and then to balance the demand and supply of rice. This is mainly because the rice consumption per capita per year has continued to decline from 135 kg in 1979 to 61.9 kg in 2016, although the rice production was relatively stable. As a result, the rice overproduction became a big social problem. As a part of that, various upland crops such as soybean, maize, minor cereals and forage crops are planted in the paddy field 10 years ago. The cultivation of these crops may settle the problem of short supply and mass import of the crops to some extent. However, a systematic remote observation of upland crops in the paddy field is very scarce. This study investigated the cultivation status of upland crops and any changes of crop harvesting in the paddy field by using an unmanned aerial vehicle (UAV). Also, we analyzed the kind of upland crops and cultivation area in the paddy field by utilizing time series observation images. A fixed wing UAV is used for the investigation. This is because it is easy to use the flight operation and to control flight management software, and it can automatically cope with various emergency states such as a strong wind and battery discharge. The material of UAV is expanded polypropylene, which has an advantage of less equipment damage and risk during takeoff and landing. We acquired observed images in Buljeong-myeon, Goesan-gun, Chungcheongbuk-do, South Korea by using fixed wing UAV in 2015 and 2016. The total investigated area reaches 6,045 ha, and among them the agricultural area was 1,377 ha. For the next step, we created an orthoimage from all images taken using Pix 4D mapper program. According to the results of image analyses in 2015, the paddy field covered total 577 ha (75.9%) with crop plant. The cultivation area of beans, ginseng, maize, tobacco and peach was 256 ha (36.6%), 63 ha (9.2%), 37 ha (5.4%), 31 ha (4.5%) and 27 ha (3.8), respectively. And in 2016, the total covered area was 586 ha (77.1%), and it was comprised of 253 ha (35.5%), 88 ha (12.3%), 29 ha (4.1%), 22 ha (3.1%) and 32 ha (4.5%) in the same order. In this study, we focused on identifying the paddy field which was converted to the cultivation of upland crops by using UAV. And, it has been indicated that the cultivation area of rice decreased from 141 ha in 2015 to 127 ha in 2016, although that of ginseng increased by 25 ha. As a result, it is expected that a lot of paddy field could be replaced by high-income crops such as ginseng and fruit tree (peach) instead of relative low-income rice. More specific and widespread research on the remote sensing in the paddy field needs to be done.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.342-348
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• 2014

Onshore great fires can normally be extinguished by firefighters using special firefighting equipment and its suitable method. However, offshore fires on the ships are to be extinguished by the crew without any supports from the onshore. Also, crews working on board are exposed to high risk of emergency evacuation due to the complicated structure arrangement of the ships and different accident types such as fire and ship collisions. As most of damage and loss of life in fire are associated with suffocation, shortening of evacuation time is an important factor to improve a survival rate. In this study, visibility in the accommodation area is analyzed by using the temperature and smoke flow which are obtained by the Fire Dynamic Simulator(FDS) as a Three-Dimensional Fire Analysis program to understand the survival rate of the crew upon the fire. The fire doors for most of ships are designed to close automatically when the fire alarm is activated. These automatic closing of the fire doors is a very effective system to delay the spread of flame and smoke flow for the unmanned spaces of the fire protected area. However, if the crew cannot escape within the estimated time, the crew inside the fire protected area will be damaged a lot. In this paper, the comparative analysis between the evacuations by using the fire door from the fire protected area and the suggested fire shielding structure in this study is carried out by the smoke flow rate and the temperature rise rate.