• Economic and Environmental Geology
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• v.52 no.1
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• pp.107-118
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• 2019

Two assertions about the process the formation of the high-purity limestone in the Taebaeksan Basin, categorized into syngenetic and epigenetic origin, are verified on the basis of its oxygen-carbon stable isotopic characteristics. The carbonate rocks sampled from the selective six high-purity limestone mines and several outcrops in the Daegi formation are featured by various colors such as the gray, light gray and dark gray. They show a wide range of oxygen stable isotope ratios (4.5 ~ 21.6 ‰), but a narrow range of carbon stable isotope ratios (-1.1 ~ 0.8 ‰, except for vein calcite), which means that they had not experienced strong hydrothermal alteration. In addition, there is no difference in the range of the oxygen stable isotope ratios by mine and color, and it is similar to the range from surrounding outcrop samples. These results indicate that the effect of the hydrothermal alteration were negligible in the generation of high-purity limestone in deposit scale. Whereas, the carbonate rocks can be divided texturally into two groups on the basis of an oxygen isotope ratio; the massive-textured or well-layered samples (>15 ‰), and the layer-disturbed (or layer-destructed) and showing over two colors in one sample (<15 ‰). In the multi-colored samples, the bright parts are characterized by the very low oxygen stable isotope ratios, compared to the dark parts, implying the increase in brightness of the carbonate rocks could be induced by the interaction between hydrothermal fluid and rock. However, these can be applied in a small scale such as one sample and are not suitable for interpretation of the generation of high-purity limestone as a deposit scale. In particular, the high oxygen isotope ratios from the recrystallized white limestone suggest that hydrothermal fluids are also rarely involved during recrystallization process. In addition, the occurrences of the high-purity limestone orebody strongly support the high-purity limestone in the area are syngenetic rather than epigenetic; the high-purity limestone layers in the area show continuous and almost horizontal shapes, and is intercalated between dolomite layers. Consequently, the overall reinterpretation based on the sequential stratigraphy over the Taebaeksan basin would play an important role to find additional reserves of the high-purity limestone.

• Korean Journal of Remote Sensing
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• v.23 no.6
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• pp.559-566
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• 2007

The generation of precise digital elevation model (DEM) is very important in coastal area where time series are especially required. Although a LIDAR system is useful in coastal regions, it is not yet popular in Korea mainly because of its high surveying cost and national security reasons. Recently, precise DEM has been made using radar interferometry and waterline methods. One of these methods, spaceborne imaging radar interferometry has been widely used to measure the topography and deformation of the Earth. We acquired ALOS PALSAR FBD mode (Fine Beam Dual) data for evaluating the quality of interferograms and their coherency. We attempted to construct DEM using ALOS PALSAR pairs - One pair is 2007/05/22 and 2007/08/22, another pair is 2007/08/22 and 2007/10/22 with respective perpendicular baseline of 820 m, 312m and respective height sensitivity of 75 m and 185m at southern of Ganghwa tidal flat, Siwha- and Hwaong-lake over west coastal of Korea peninsula. Ganghwa tidal flat has low coherence between 0.3 and 0.5 of 2007/05/22 and 2007/08/22 pair. However, Siwha-lake and Hwaong-lake areas have a higher coherence value (From 0.7 and 0.9) than Ganghwa tidal area. The reason of difference coherence value is tidal condition between tidal flat area (Ganghwa) and reclaimed zone (Siwha-lake and Hwaong-lake). Therefore, DEM was constructed by ALOS PALSAR pair over Siwha-lake and Hwaong-lake. If the temporal baseline is enough short to maintain the coherent phases and height sensitivity is enough small, we will be able to successfully construct a precise DEM over coastal area. From now on, more ALOS PALSAR data will be needed to construct precise DEM of West Coast of Korea peninsular.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.7
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• pp.846-851
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• 2009

This study was carried out to investigate the effects of Puerariae Flos extracts on antioxidative potential, free radical generation and the lipid levels in rats. Sprague-Dawley rats were divided into 2 diet groups: AIN-76 diet (control group) and modified AIN-76 diet (cholesterol 0.5%) with 0.5% Puerariae Flos extracts for 4 weeks. Body weight and feed efficiency ratios from both groups were not significantly different. Antioxidative potentials significantly increased in the group fed Puerariae Flos extracts compared to control group (p<0.05). However, there was no difference in free radical generation. The weight of organs, such as heart, kidney, liver, and spleen, in rats were not different in both groups. The ratio HDL cholesterol to total cholesterol in the Puerariae Flos group was significantly higher than in the control group, while the other serum lipid parameters (total cholesterol, HDL cholesterol, triglyceride, and phospholipids) were not different between the two groups. These results imply that supplementation of Puerariae Flos extracts may beneficially contribute to improve antioxidant potential and to decrease the lipid levels in the blood.

• Korean Journal of Poultry Science
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• v.30 no.1
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• pp.17-28
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• 2003

A feeding trial was carried out to evaluate the effects of feeding Lactobacillus reuteri culture(LRC) on the performance, nutrients digestibility, intestinal microflora, serum metabolites, ammonia generation and litter dampness in broiler chicks. Four hundred eighty, one day old male chicks were fed into none, 0.1, 0.2 and 0.4% of LRC supplementation fer seven weeks. Basal diets excluded antibiotics contained ME 3,100, 3,100 kcal/kg, and CP 22.0, 20.0% for starter and grower, respectively. Weight gain of chicks fed LRC was significantly higher than no supplemental group in overall period(P<0.05). Feed intake was the highest in the 0.1% LRC, but not statistically different from other treatments. Feed conversion showed no significance among treatments. Viable Lactobacillus spp. number of chicks fed 0.2 and 0.4% LRC was significantly higher in cecum at seven weeks of age compared to the none(P<0.05). The tendency of anaerobes number was similar to Lactobacillus spp in ileum and cecum. Total number of E. coli and Salmonella were no difference in all treatments. In serum metabolites, feeding LRC increased triglyceride, and inorganic phosphorus, but no different total protein, albumin, total cholesterol, glucose, blood urea nitrogen and Ca. Nutrients digestibility improved significantly in 0.4% LRC compared to that of none(P<0.05). Fecal NH$_3$, gas generation was greatly decreased in the LRC supplemental groups(P<0.05). Moisture contents of bedding was also significantly decreased in LRC feeding group. It was concluded from the present study that feeding Lactobacillus reuteri culture improved the growth performance and nutrients digestibility of broiler chicks and minimize the fecal noxious gas emission.

• Development and Reproduction
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• v.21 no.2
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• pp.121-130
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• 2017

4-Nonylphenol (NP) is a surfactant that is a well-known and widespread estrogenic endocrine disrupting chemical (EDC). Although it has been known that the affinity of NP to ERs is low, it has been suggested that low-dose NP has toxicity. In the present study, the endocrine disrupting effects on reproduction, and the weight of gonads, epididymis, and uterus were evaluated with the chronic lower-dose NP exposing. This study was designed by following the OECD test guideline 443 and subjected to a complete necropsy. In male, NP had an effect on the weight of the testis and epididymis in both $F_0$ and $F_1$. In females, NP decreased the weight of ovary and uterus in $F_0$ but not in pre-pubertal $F_1$ pubs. Fertility of male and female in $F_0$ or $F_1$ was no related with NP administration. The number of caudal-epididymal sperm by body weight (BW) was not different between groups in both $F_0$ and $F_1$. Besides, the difference of the sperm number between generations was not detected. The number of ovulated oocytes was similar between groups in $F_0$, but significantly decreased in NP 50 group of $F_1$. The litter size and sex ratios of offspring in $F_1$ and $F_2$ were not different. The accumulated mating rate and gestation period were not affected by the NP administration. Those results shows that chronic lower-dose NP administration has an effect of endocrine disruptor on the weight of gonads and epididymis of $F_0$ and $F_1$ but not in reproduction. Based on the results, it is suggested that chronic lower-dose NP exposing causes endocrine disruption in the weight of gonad and epididymis but not in the reproductive ability of next generations.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.85-99
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• 2020

Reservoir is an important infrastructure of our society because it can store immense amount of water for various usages - manufacturing, agriculture, drinking, power generation, tourism etc. For maintenance of reservoir, various efforts in administrative and technological aspects are periodically conducted and monitoring the conditions of reservoir bed is the first priority for maintenance of reservoir. To check the conditions of reservoir bed, we measured depth of reservoir by using echo sounder, which is relatively reliable, prior to discharging of stored water and surveyed topography of reservoir by using UAV after discharging of water. Then, we conducted interpolation of measured depth of water by means of inverse distance weighting interpolation, Kriging interpolation, minimum curvature interpolation and radial basis function interpolation and calculated the volume of reservoir for each interpolation method. We compared the calculated volume of reservoir with the volume of water calculated by UAV after discharging of water and found the following results: First, as results of the above processes, we found that the Kriging interpolation was 97% correct in measurement of the volume of reservoir. Second, as results of comparison of differences between topographical areas and interpolated areas after selection of cross section for comparison, Kriging interpolation was found to have the most similar configuration with the topographical configuration by showing the least difference in the area of cross section. Therefore, it is determined that the optimal modeling of reservoir bed with the water depth data measured by echo sounder shall provide basic information for efficient maintenance of reservoir.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.2
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• pp.81-95
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• 2022

The present study was performed to investigate the effects of NH₃-N and nitrifying microorganisms on the increased BOD of downstream of the Yeongsan river in Gwangju. Water samples were collected periodically from the 13 sampling sites of rivers from April to October 2021 to monitor water qualities. In addition, the trends of nitrogenous biochemical oxygen demand (NBOD) and microbial clusters were analyzed by adding different NH₃-N concentrations to the water samples. The monitoring results showed that NH₃-N concentration in the Yeongsan river was 22 times increased after the inflow of discharged water from the Gwangju 1st public sewage treatment plant (G-1-PSTP). Increased NH₃-N elevated NBOD levels through the nitrification process in the river, consequently, it would attribute to the increase of BOD in the Yeongsan river. Meanwhile, there was no proportional relation between NBOD and NH₃-N concentrations. However, there was a significant difference in NBOD occurrence by sampling sites. Specifically, when 5 mg/L NH₃-N was added, NBOD of the river sample showed 2-4 times higher values after the inflow of discharged water from G-1-PSTP. Therefore, it could be thought other factors such as microorganisms influence the elevated NBOD levels. Through next-generation sequencing analysis, nitrifying microorganisms such as Nitrosomonas, Nitroga, and Nitrospira (Genus) were detected in rivers samples, especially, the proportion of them was the highest in river samples after the inflow of discharged water from G-1-PSTP. These results indicated the effects of nitrifying microorganisms and NH₃-N concentrations as important limiting factors on the increased NBOD levels in the rivers. Taken together, comprehensive strategies are needed not only to reduce the NH₃-N concentration of discharged water but also to control discharged nitrifying microorganisms to effectively reduce the NBOD levels in the downstream of the Yeongsan river where discharged water from G-1-PSTP flows.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.189-207
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• 1988

In almost all biologic systems, mechanically induced electric charge separation is a fundamental phenomenon. Since the hypothesis was established that the generation of electric potentials in bone by mechanical stress including muscular force might control the activity in bone by mechanical stress including muscular force might control the activity of osseous cells and their biopolymeric byproduct, the concept of electrically mediate growth mechanism, which involves biological growth and bone remodeling by any means, in living systems has been applied clinically and experimentally to orthopedic fracture repair, the regulation of orthodontic tooth movement, epiphyseal cartilage regeneration, etc. On the other hand, recent numerous research data available show apparently that the mandibular condyle has the characteristics of growth center as well as growth site. In addition, there exists a considerable difference of opinion as to the role of external pterygoid muscle in condylar growth. In view of these evidences, this. experiment was performed to investigate the effect of the galavic current on the growth of the mandible and condyle for elucidating the nature of condylar growth. The bimetallic device was composed of silver and platinum electrode connected with resistor (3.9 Mohm), which was expected to produce galvanic current of 23.6 nA according to the galvanic principle. The 25 Sprague-Dawley rats were divided into two group, 2 week group comprising 8 animals exposed to satanic current for 2 weeks and 3 control animals not exposed for 2 weeks, 4 week group comprising 10 animals in experimental group and 4 animals in control group applied for 4 weeks respectively. The experimental rats were subjected to application of the galvanic current invasively to codylar head surface and the control groups with sham electrode. On the basis of anatomic and histologic data from the mandibular condyle of experimental and control group, the following results were obtained. 1. After 2 weeks, there was no increase of mandibular size in experimental group over that of the control group. 2. After 4 weeks, the size of the condylar head was larger in experimental group than that of the control. 3. In 2 week group, the thickness of the mitotic compartment and hypertrophic chondroblastic layer was increased in experimental group. 4. In 4 week group, the number and the size of the hypertrophic chondroblasts were increased significantly on experimental group over that of the control group. 5. The application of the satanic current caused an increase in chondrocytic hypertrophy and intercellular matrix in both groups.

• Journal of Periodontal and Implant Science
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• v.24 no.3
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• pp.458-471
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• 1994

To evaluate the periodontal status of Korean adults, 3,988 adults(20-69 years old) who lived in Kwangju, Chonnam, Taegu, and Kyungbuk districts were periodontally examined by plaque index(PI), calculus index(CI), gingival index(GI), periodontal disease index (PDI), and papillary bleeding index(PBI). The periodontal examination charts were grouped according to age and sex. And subsequently 200 periodontal examination charts in each age group were randomly selected according to sex. The differences of the indices among age groups and those between male and female in each age group were statistically analyzed by Chi-Square test. In PI, CI, GI, PDI, and PBI, there was no statistical significance in the difference between male and female in each age group(p>0.05). In male, PI of 60s age group($1.44{\pm}0.68$) was significantly higher than that of any age group(p<0.05), and in female PI of 20s age group($0.86{\pm}0.39$) was significantly lower than that of any other age group(p<0.05). CI of 60s age group in both male($1.67{\pm}0.70$) and female($1.63{\pm}0.91$) was significantly higher than that of any age group(p<0.05). GI of 20s age group in both male($0.85{\pm}0.66$) and female($0.67{\pm}0.60$) was significantly lower and GI of 60s age group in both male($1.37{\pm}0.60$) and female($1.44{\pm}0.84$) was higher than that of any age group(p<0.05). PDI in male was the lowest in 20s age group($0.70{\pm}0.73$), and was the highest in 60s age group($4.93{\pm}1.96$) (p<0.05). In female PDI of 20s age group($0.71{\pm}0.74$) was significantly lower than that of any age group(p<0.05). In male PBI of 20s age group($0.38{\pm}0.31$) was significantly lower than that of any age group(p<0.001). PBI in female was the lowest in 20s age group($0.35{\pm}0.30$) (p<0.001), and was the highest in 60s age group($1.09{\pm}0.76$) (p<0.05). The data insist that all the young populations of 20s age group should be interested in routine check for early diagnosis and prevention of periodontal disease, and a special education program of periodontal health care for young generation must be prepared, and the periodic recall check system for periodontal examination of middle age group must be supported by government.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.16-16
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• 2010

GaN-based light-emitting diodes (LEDs) are attracting great interest as candidates for next-generation solid-state lighting, because of their long lifetime, small size, high efficacy, and low energy consumption. However, for general illumination applications, the external quantum efficiency of LEDs, determined by the internal quantum efficiency (IQE) and the light extraction efficiency, must be further increased. The IQE is determined by crystal quality and epitaxial layer structure and high value of IQE more than 70% for blue LEDs have been already reported. However, there is much room for improvement of light extraction efficiency because most of the generated photons from active layer remain inside LEDs by total internal reflection at the interface of semiconductor with air due to the high refractive index difference between LEDs epilayer (for GaN, n=2.5) and air (n=1). The light confining in LEDs will be reabsorbed by the metal electrode or active layer, reducing the efficacy of LEDs. Here, we present the first demonstration of enhanced light extraction by forming a MgO nano-pyramids structure on the surface of vertical-LEDs. The MgO nano-pyramids structure was successfully fabricated at room temperature using conventional electron-beam evaporation without any additional process. The nano-sized pyramids of MgO are formed on the surface during growth due to anisotropic characteristics between (111) and (200) plane of MgO. The ZnO layer with quarter-wavelength in thickness is inserted between GaN and MgO layers to increase the critical angle for total internal reflection, because the refractive index of ZnO (n=1.94) could be matched between GaN (n=2.5) and MgO (n=1.73). The MgO nano-pyramids structure and ZnO refractive-index modulation layer enhanced the light extraction efficiency ofV-LEDs with by 49%, comparing with the V-LEDs with a flat n-GaN surface. The angular-dependent emission intensity shows the enhanced light extraction through the side walls of V-LEDs as well as through the top surface of the n-GaN, because of the increase in critical angle for total internal reflection as well as light scattering at the MgO nano-pyramids surface.