• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.553-562
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• 2017

In these days, agricultural reservoirs are considered as a useful resource for recreational purposes, tour and cultural amenity for vicinity communities as well as irrigation water supply. However, many of the agricultural reservoirs are showing a eutrophic or hyper-eutrophic state and high level of organic contamination. In particular, about 44.7% of the aged agricultural reservoirs that constructed before 1945 exceed the water quality criteria for irrigational water use. In addition to external loading, internal nutrient loading from bottom sediment may play an important role in the nutrient budget of the aged reservoirs. The objectives of this study were to characterize variations of thermal structure of a shallow M reservoir (mean depth 1.7 m) and examine the potential of internal nutrient loading by continuous monitoring of vertical water temperature and dissolved oxygen (DO) concentration profiles in 2015 and 2016. The effect of internal loading on the total loading of the reservoir was evaluated by mass balance analysis. Results showed that a weak thermal stratification and a strong DO stratification were developed in the shallow M Reservoir. And, dynamic temporal variation in DO was observed at the bottom of the reservoir. Persistent hypoxic conditions (DO concentrations less than 2 mg/L) were established for 87 days and 98 days in 2015 and 2016, respectively, during the no-rainy summer periods. The DO concentrations intermittently increased during several events of atmospheric temperature drop and rainfall. According to the mass balance analysis, the amount of internal $PO_4-P$ loading from sediment to the overlying water were 37.9% and 39.7% of total loading during no-rainy season in 2015 and 2016, respectively on August when algae growth is enhanced with increasing water temperature. Consequently, supply of DO to the lower layer of the reservoir could be effective countermeasure to reduce nutrient release under the condition of persistent DO depletion in the bottom of the reservoir.

• Economic and Environmental Geology
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• v.26 no.2
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• pp.129-134
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• 1993

At the Janggun mine, boulangerite usually occurs as needles or irregularly-shaped grains, up to $500{{\mu}m}$ in longer dimensions, closely associated with galena, minerals of a tetrahedrite-freibergite series and bournonite in the peripheries of South A and B orebodies and the zone of manganoan carbonates surrounding them. In some places, especially at the top of South B orebody, it occures as "feather ore" consisting of its fine needles or "hairs" in small drusy cavities together with fine-grained euhedral galena, pyrite, manganoan carbonates, quartz, etc. In reflected light, it is bluish grey in colour exhibiting moderate bireflectance and is strongly anisotropic without any internal reflections. Reflectance in air is $R_{max}=43.2$, $R_{min}=35.7$ percent at wavelength of 580 nm, and VHN: $146-173\;kg/mm^2$ at a 50 g-load. The chemical composition on the average from 23 complete spot analyses by electron microprobe is, Pb 56.1, Sb 25.1, S 18.5, Total 99.6 (all in weight percent); the corresponding chemical formula calculated on the basis of S=11 is; $Pb_{5.16}Sb_{3.93}S_{11.0}$ which fulfils approximately the ideal formula $Pb_5Sb_4S_{11}$. The strongest reflections on the X-ray diffraction pattern are; $3.73\;{\AA}\;(10)$, $3.22\;{\AA}\;(5)$, $3.03\;{\AA}\;(4)$ and $2.82\;{\AA}\;(5)$ and the pattern is in harmonic with space group $C^5_{2h}-P2_1/a$. From the textural evidence of the microscopic observations, the mineral is considered to have been formed at the latest stage of hydrothermal lead-zinc-silver mineralization.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.187-197
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• 2006

A mathematical modeling program called Hydrological Simulation Program-FORTRAN (HSPF) developed by the United States Environmental Protection Agency(EPA) was applied to the Yongdam Watershed to examine its applicability for loading estimates in watershed scale. It was run under BASINS (Better Assessment Science for Integrating point and Nonpoint Sources) program, and the model was validated using monitoring data of 2002 ${\sim}$ 2003. The model efficiency of runoff was high in comparison between simulated and observed data, while it was relatively low in the water quality parameters. But its reliability and performance were within the expectation considering complexity of the watershed and pollutant sources and land uses intermixed in the watershed. The estimated pollutant load from Yongdam watershed for BOD, T-N and T-P was 1,290,804 kg $yr{-1}$, 3,753,750 kg $yr{-1}$ and 77,404 kg $yr{-1}$,respectively. Non-point source (NPS) contribution was high showing BOD 57.2%, T-N 92.0% and T-P 60.2% of the total annual loading in the study area. The NPS loading during the monsoon rainy season (June to September) was about 55 ${\sim}$ 72% of total NPS loading, and runoff volume was also in a similar rate (69%). However, water quality was not necessarily high during the rainy season, and showed a decreasing trend with increasing water flow. Overall, the BASINS/HSPF was applied to the Yongdam watershed successfully without difficulty, and it was found that the model could be used conveniently to assess watershed characteristics and to estimate pollutant loading in watershed scale.

• Korean Journal of Environmental Agriculture
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• v.38 no.3
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• pp.166-172
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• 2019

BACKGROUND: Increase in the ratio of small berries in blueberry production decreases the farmers' profits due to weakening market competitiveness and lowering harvest efficiency. One of the reasons for increased small berries is over fruit-load. For improving productivity and competitiveness of blueberry in Korea, hand-thinning can be applied to increase fruit quality before the developing adequate chemical thinning methods. This study was conducted to investigate the proper timing and methods for floral buds thinning in rabbiteye blueberry. METHODS AND RESULTS: Eight years old bushes of rabbiteye bluberries 'Brightwell' as a primary cultivar and 'Powderblue' as a pollinizer were used for this study. Fruit size distribution by leaf-to-fruit ratio was investigated by counting the number of leaves and fruits in canes of 127 'Brightwell' plants whose fruit set varied. Fifty percent of flowers/floral buds were removed in four different floral buds stages such as bud swell, late pink bud, full bloom, and petal fall, and the consumed time for thinning and fruit characteristics were recorded to investigate the effect and proper timing of floral buds thinning. Fruit weight and soluble solids content tended to increase in proportion to leaf-to-fruit ratio and the production of the number of fruits less than 13 mm in diameter decreased when leaf-to-fruit ratio was more than 2.5. Manual floral buds thinning by hands was fastest in full bloom stage and slowest in bud swelling stage. In all cultivars, fruit size was significantly smaller in non-thinning treatment than thinning, and there was, however, no significant difference in total fruit yield. The number of fruits less than 13 mm in diameter increased in both cultivars as floral buds thinning was delayed. Consumed time for picking 90% berries out of total berries per bush was shortest in full bloom stage thinning in 'Brightwell' and bud swelling, full bloom thinning in 'Powderblue'. These were 25 and 20 days faster than no thinning, respectively. CONCLUSION: Although the effect of floral buds thinning varied depending on the cultivars, our results confirmed that floral buds thinning was effective for the early intensive harvesting and the increase of the large fruit ratio and the harvesting productivity. Also, in order to increase thinning efficiency, it is recommended to remove the flower buds before the full bloom stage.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.273-291
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• 2020

The strength characteristics of the three orthogonal splitting planes, known as rift, grain and hardway planes in granite quarries, were examined. R, G and H specimens were obtained from the block samples of Jurassic granites in Geochang and Hapcheon areas. The directions of the long axes of these three specimens are perpendicular to each of the three planes. First, The chart, showing the scaling characteristics of three graphs related to the uniaxial compressive strengths of R, G and H specimens, were made. The graphs for the three specimens, along with the increase of strength, are arranged in the order of H < G < R. The angles of inclination of the graphs for the three specimens, suggesting the degree of uniformity of the texture within the specimen, were compared. The above angles for H specimens(θ^H, 24.0°~37.3°) are the lowest among the three specimens. Second, the scaling characteristics related to the three graphs of RG, GH and RH specimens, representing a combination of the mean compressive strengths of the two specimens, were derived. These three graphs, taking the various N-shaped forms, are arranged in the order of GH < RH < RG. Third, the correlation chart between the strength difference(Δσ_t) and the angle of inclination(θ) was made. The above two parameters show the correlation of the exponential function with an exponent(λ) of -0.003. In both granites, the angle of inclination(θ^RH) of the RH-graph is the lowest. Fourth, the six types of charts, showing the correlations among the three kinds of compressive strengths for the three specimens and the five parameters for the two sets of microcracks aligned parallel to the compressive load applied to each specimen, were made. From these charts for Geochang and Hapcheon granites, the mean value(0.877) of the correlation coefficients(R²) for total density(Lt), along with the frequency(N, 0.872) and density(ρ, 0.874), is the highest. In addition, the mean values(0.829) of correlation coefficients associated with the mean compressive strengths are more higher than the minimum(0.768) and maximum(0.804) compression strengths of three specimens. Fifth, the distributional characteristics of the Brazilian tensile strengths measured in directions parallel to the above two sets of microcracks in the three specimens from Geochang granite were derived. From the related chart, the three graphs for these tensile strengths corresponding to the R, G and H specimens show an order of H(R1+G1) < G(R2+H1) < R(R1+G1). The order of arrangement of the three graphs for the tensile strengths and that for the compressive strengths are mutually consistent. Therefore, the compressive strengths of the three specimens are proportional to the three types of tensile strengths. Sixth, the values of correlation coefficients, among the three tensile strengths corresponding to each cumulative number(N=1~10) from the above three graphs and the five parameters corresponding to each graph, were derived. The mean values of correlation coefficients for each parameter from the 10 correlation charts increase in the order of density(0.763) < total length(0.817) < frequency(0.839) < mean length(Lm, 0.901) ≤ median length(Lmed, 0.903). Seventh, the correlation charts among the compressive strengths and tensile strengths for the three specimens were made. The above correlation charts were divided into nine types based on the three kinds of compressive strengths and the five groups(A~E) of tensile strengths. From the related charts, as the tensile strength increases with the mean and maximum compressive strengths excluding the minimum compressive strength, the value of correlation coefficient increases rapidly.

• The Journal of Korean Obstetrics and Gynecology
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• v.30 no.4
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• pp.18-44
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• 2017

Purpose: The object of this study was to observe the anti-climacterium activity of Gagamguibiondam-tang (GGOT) on ovariectomized (OVX) rats, a well-documented rodent models resembles with women postmenopausal climacterium symptoms, as including cardiovascular diseases, obesity, hyperlipidemia, osteoporosis, organ steatosis and mental disorders. Methods: In this study, anti-climacteric effects were evaluated separated into three categories; 1) anti-obese, 2) anti-uterine atrophy and 3) anti-osteoporotic effects. Five groups were used (8 rats in each group); sham control, OVX control, GGOT 500, 250 and 125 mg/kg administered groups. Twenty-eight days after bilateral OVX surgery, GGOT were orally administered, once a day for 84 days, and then the changes on the body weight and gain during experimental periods, serum estradiol levels, abdominal fat pad and uterus weights with histopathology of abdominal fat pads (total thickness and mean adipocyte diameters) and uterus (total, epithelial and mucosal thickness, percentages of uterine gland regions) for anti-obese and estrogenic effects. In addition, femur, tibia and fourth or fifth lumbar vertebrae (L4 or L5) wet, dry and ash weights, mineral density (BMD), bone strength (failure load), serum osteocalcin and bone specific alkaline phosphatase (bALP) contents, histological and histomorphometrical analyses - bone mass and structure with bone resorption, were monitored for anti-osteoporosis activity. Results: As a result of OVX, noticeable increases of body weight and gains, food and water consumption, weights of abdominal fat pad deposited in dorsal abdominal cavity, serum osteocalcin levels were demonstrated in this experiment with decrease of uterus, femur, tibia and L5 weights, serum bALP and estradiol levels. In addition, marked hypertrophic changes of adipocytes located in deposited abdominal fat pads, uterine disused atrophic changes, decreases of bone mass and structures of femur, tibia and L4 were also observed in OVX control rats with dramatic increases of bone resorption markers, the Ocn and OS/BS at histopathological and histomorphometrical analysis in this study as compared with sham-operated control rats, suggesting the estrogen-deficient climacterium symptoms - obese and osteoporosis were induced by OVX, respectively. However, these estrogen-deficient climacterium symptoms induced by bilateral OVX in rats were significantly inhibited by 84 days of continuous oral treatment of GGOT 500, 250 and 125 mg/kg, respectively. Especially, GGOT 500, 250 and 125 mg/kg showed clear dose-dependent inhibitory activities on the OVX-induced climacterium signs. Conclusion: The results suggest that oral administration of GGOT 500, 250 and 125 mg/kg has clear dose-dependent favorable anti-climacterium effects - estrogenic, anti-obese and anti-osteoporotic activities in OVX rats in this experiment.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.269-275
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• 2013

Purpose: The aim of this retrospective study was to evaluate the influence of implant diameter, length and placement to implant stability. Materials and methods: Total 90 implants (US II plus$^{TM}$, Osstem co, Busan, Korea) of 72 patients were determined as experimental samples. The factors of diameters(${\phi}$ 4 mm, ${\phi}$ 5 mm), lengths (10 mm, 11.5 mm, 13 mm), and implant placement (maxilla, mandible) were analyzed. The stability of the implants was measured by resonance frequency analysis (RFA) at the time of implant placement and impression taking. The difference of ISQ values according to patient's gender was evaluated by Independent t-test. ISQ values were compared between implant diameter, length and placement using one-way ANOVA and Tukey HSD test (${\alpha}=.05$). To compare ISQ values between at the time of surgery and impression taking, paired t-tests were used (${\alpha}=.05$). Results: The change of implant length did not show significant different on the ISQ value (P>.05). However, 5 mm diameter implants had higher ISQ values than 4 mm diameter implants (P<.05). Implants placed on the mandible showed significantly higher ISQ values than on the maxilla (P<.05). Conclusion: In order to increase implant stability, it is better to select the wider implant, and implants placed on mandible are possible to get higher stability than maxilla. ISQ values at impression taking showed higher implant stability than ISQ values at implant placement, it means that RFA is clinically effective method to evaluate the change of implant stability through the osseointegration. The consideration of the factors which may affect to the implant stability will help to determine the time of load applying and increase the implant success rate.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.296-304
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• 2011

This study was carried out to investigate the relation between water quality and structure of the aquatic ecosystem in the Lake Gachang from February to December in 2010. The annual mean COD (Chemical Oxygen Demand) in Lake Gachang was 3.5 mg $L^{-1}$, indicating, level II of environmental standards and the trophic state was mesotrophic. The seasonal succession of phytoplankton showed that Bacillariophyceae was mostly dominant species throughout the year except August. In case of zooplankton, rotifers dominate in the most seasons, but copepod (Nauplii) in August. The macrophyte plants showed diverse species composition consisted of 9 varieties, 77 species, 64 genera, 34 families and 24 orders. Surveyed species of macroinvertebrates were classified into 1 phyla, 2 classes, 4 orders, 7 families, 9 species. The macroinvertebrates showed FFG (Functional Feeding Groups) such as GC (Gathering-Collector) and SH (Shedder). A total of 42 species of fish was collected including $Zacco$ $koreanus$ and $Coreoperca$ $herzi$. In this study, we investigated environmental factors including pollutant source, load, water quality and distribution characteristics of biota such as phytoplankton, zooplankton, macrophyte plants, macroinvertebrates, fish.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.324-332
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• 2014

In order to reveal the long-term variations of water quality in Jinhae Bay, water qualities had been monitored at 9 survey stations of Jinhae Bay during 2000~2012. The surface and bottom waters concentrations of chemical oxygen demand (COD), dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and chlorophyll-a (Chl.-a) were higher at the survey stations of Masan Bay than the stations of other Bays. Especially, station 1 which is located at the inner area of Masan Bay had the highest values in the concentrations of COD, DIN, and Chl.-a because there were terrestrial pollutant sources near the station 1 and sea current had not well circulated in the inner area of Masan Bay. In factor analysis, the station 1 also had the highest factor values related to factors which increase organic matters and nutrients in surface and bottom waters of Masan Bay. However, the stations (st.5, st.6, st.7, st.8, and st.9) of other Bays had lower values of the factors. In time series analysis, the COD concentrations of the bottom waters at 8 stations except for station 1 distinctly decreased. However, the COD concentrations of the surface waters showed no distinct decrease trends at all stations. In the concentrations of nutrients (DIN and DIP) of both surface and bottom waters, there were tremendous decrease trends at all stations. Therefore, these distinct decrease trends of the COD in bottom waters and the nutrients in surface and bottom waters of Jinhae Bay could have been associated with water improvement actions such as TPLMS (total pollution load management system).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.4
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• pp.535-547
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• 2019

In this study, the heavy metal analysis in sediments (surface sediments, sediments cores and settling particles) from Shihwa Lake has been carried out to evaluate the changes of metal pollution levels in sediments after the operation of Tidal Power Plant (TPP). The average concentrations of metals in surface sediments sampled in 2015 were 8% (Cd)~31% (Zn, Hg) lower than in 2009 before TPP operation. Results of calculating the pollution load index (PLI) with 8 metals, the PLI value in 2015 showed a 18% decrease compared to 2009. However, Cu, Zn, Pb concentrations of surface sediments in 2015 at the upper region around industrial complex still exceeded the TEL (threshold effect level) values for sediment quality guideline in Korea. After the operation of TPP, the metal contaminated depths were increasing from 15 cm to 30 cm at S6 site and from 8 cm to 20 cm at S7 site, respectively. Our data showed that the mean concentration of heavy metals in core samples decreased but the contaminated depth increased. The average of the total sedimentation flux for particulate matter increased by 3.2 times from 32.5 g/㎡/d in 2009 to 103.5 g/㎡/d in 2015. This showed that the bottom sediments were resuspended by the operation of TPP, resulting in an increase of particulate matter in the water column. These results suggest that the sediments contaminated with heavy metals seem to be resuspended and relocated due to the water current caused by the operation of TPP. Cr, Cu, Zn, Pb and Cd were highly exceeding the TEL values in the upstream region and accumulated more than 40 cm of sediment depth, indicating that heavy metal contamination through industrial activity were still a serious environmental problem of Shihwa Lake. Although the metal pollution of Shihwa Lake has been slightly reduced, the contaminated sediments with heavy metals inside of Shihwa Lake might be discharged to outer sea after the resuspension by TPP operation. It is necessary for the advanced scientific approach and political decision to drastically reduce the heavy metal pollution of the study region.