• 한국해양학회지
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• v.27 no.3
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• pp.250-258
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• 1992

The oxygen isotope composition of surface waters in the Bransfield Strait was determined as one extra state variable in order to characterize water masses in the region, since salinity is significantly modified due to the freezing and ice-melting in the polar region. The salinity, temperature, and $\delta$/SUP 18/O values vary from 34.0 to 34.5$\textperthousand$, -.05 to 2.1$^{\circ}C$ and -0.50 t -0.26$\textperthousand$, respectively. The combined effects of evaporation, precipitation, freezing, ice-melting are reflected in the widely scattered data. Although it is small, the distribution of $\delta$/SUP 18/O of the Bransfield Strait is strongly affected by the freezing-ice melting rather than the evaporation-precipitation. The ice melted fresh water which has higher temperature, depleted salinity and nutrients may be injected to the Bransfield Strait from the north. The concentrations of nutrients are decreasing gradually from the north to the south. The waters were characterized by two groups of higher (about 19.4) and lower N/P ratio (about 16.7). The lower N/P ratio is found in the northern part where ice-melted fresh water is injected. and the higher N/P ratio is found in the southern part of the Bransfield Strait. Although more precise work is needed, the deference of N/P ratio can be an evidence of the ice melted water injection to the Bransfield Strait. Chlorophyll a concentrations, in general, increase from northwest (Waddell Sea) to the southeast (Smith and Hosseason Islands). Probably the injection of nutrient depleted fresh water from the ice melting reduce the chlorophyll a concentration.

• Journal of Bio-Environment Control
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• v.13 no.1
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• pp.51-55
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• 2004

The most commonly used inorganic nutrient compositions such as Murashige & Skoog medium have been optimized for heterotrophic growth. Therefore, they may not be optimal for photomixotrophic and photoautotrophic growth of plantlets. In photomixotrophic micropropagation, emdium sugar level is often lowered, while light and $CO_2$ levels in vessel are raised, and chlorophyllous explants are used to facilitate photosynthetic carbon acquisition. In a factorial experiment effect of addition (+) and omission(_) of organic materials (OM, 0.5 g ${\cdot}$ $m^{-3}$ each of thiamine, nicotinic acid and pyridoxine and 100 ${\cdot}$ $m^{-3}$ myo-inositiol) combined with three sucrose levels (0, 15, and 30 kg ${\cdot}$ $m^{-3}$) was tested on the growth of potato plantlets. Each of nodal cuttings with a leaf was cultured on 0.1${\times}$$10^{-4}m^{-3}$) MS agar ( 8 kg ${\cdot}$ $m^{-3}$) medium (pH 5.80 before autoclave) in glass test tubes (100 mm${\times}$25mm) capped with a sheet of transparent film with a 6 mm diameter gas permeable filter (5.1 air exchanges ${\cdot}$$h^{-1}$). Cultures were maintained in a room for 27 days at $23^{\circ}C$, 50% RH, 350-450${\mu}mol\;{\codt}\;mol^{-1}CO_2$, 16 h ${\cdot}$ $d^{-1}$ photoperiod at 13${\mu}mol\;{\codt}\;m\;{\codt}\;s^{-1}$ PPFD provided by white cool fluorescent lamps. Growth of potato plantlet in the +OM and -OM treatments were similar, while medium pH was 0.2 scale lower in the latter. Dry weight, % dry matter, and stem diameter enhanced, while shoot to root dry weight ratio, leaf area, chlorophyll concentration per gram dry weight, and medium pH decreased with increasing initial sucrose level. Interaction between OM and sucrose levels was observed in shoot length and medium pH. Results indicate that OM can be omitted from the medium without detrimental effect while addition of sucrose was beneficial for the photomixotrophic growth of potato plantlets under raised light and $CO_2$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.453-462
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• 1998

Macrobenthic community structure was studied at thirteen stations in Taebudo subtidal area, Korea, from July to October 1996. Triple macrobenthos samples were collected using a van Veen grab (0.1 $m^2$) at each station during the study period. A total of 209 species of macrobenthos was sampled with a mean density of 1,093 ind./$m^2$ and biomass of 134,86 g/$m^2$. Of these, there were 72 species of polychaetes ($34.5\%$), 69 crustaceans ($33.0\%$) and 49 molluscs ($23.4\%$). Polyalaetes were represented as a density-dominant faunal group with a mean density of 608 ind./$m^2$, comprising $55.6\%$ of the total benthic animals. It was followed by crustaceans with 307 ind./$m^2$($28.1\%$ of the total density), Echinoderms were represented as a biomass-dominant faunal group with a mean biomass of 54.21 g/$m^2$($40.2\%$ of total biomass). Total number of species and diversity were low in the inner part of the study area with high mud content and high in the offshore stations of mixed sediments. Major dominant species were three polychaetes, Heteromastus filifomis, Scoloplos armiger and Tharyx sp. whose mean densities were 70 ind./$m^2$, 67 ind./$m^2$, and 66 ind./$m^2$, respectively. Cluster analysis showed that the study area could be divided into five stational groups based on the faunal composition, that is, the innermost stations, coastal stations, transitional stations and two offshore station groups. The species diversity of these groups increased from the inner stational group toward the outer groups.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.229-240
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• 2009

The high temperature and water content in soil profile probably affect the physiological disorder especially on cool-season turfgrasses in warm and humid weather of Korean summer. The purpose of this research was to analyze the effect of soil temperature and water content on the growth and stress response of creeping bentgrass(Agrostis palustris Huds.) under a humid and warm temperature. USGA(United State of Golf Association) green profile in laboratory test, Daily temperature changes were tested under a dried sand, 70% water content of field capacity, and saturated condition at $34^{\circ}C$ of the USGA green in lab. In this test, the dried sand reached to $80^{\circ}C$, however, the surface temperature decrease of $10^{\circ}C$ on the saturated condition. In the thermal properties test in field, thermal conductivity, thermal diffusivity, and soil temperature were increased followed by irrigation practise. In the water-deficient condition, the highest soil temperature was reached temporally right after irrigation, however, the excessive soil water content higher than field water holding capacity showed the highest soil temperature after a while. This result indicated that a heat damage to root system was caused from the thermal conductivity of a high surface soil temperature. The excessive irrigation when a high turf surface temperature should occur a negative result on tufgrass growth, moreover, it would be fatal to root growth of creeping bentgrass, especially when associated with a poor draining system on USGA sand green. Overall, this study shows that high soil temperature with water-excessive condition negatively affects on cool-season grass during the summer season, suggesting that excessive irrigation, over 70% field capacity of soil condition, does not help to reduce soil temperature for summer season in Korea. In the study that cool-season grass were treated with different water content of soil, The soil had higher temperature and more water holding capacity when treatment rate of soil conditioner was increased. The best growth at the normal water condition and the worst state of growth at thee water-excessive condition were observed.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.2
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• pp.95-106
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• 2021

The SO₄ in the jarosite structure can be substituted by other oxyanions, and therefore, the transition of jarosite to goethite plays a very important role in controlling the behavior of oxyanions. In this study, the phase change according to the species of the oxyanion in jarosite and the related behavior of the oxyanion was studied by mineralogical and geochemical methods when jarosite, which is coprecipitated with various oxynions, undergoes a phase change by a reductive dissolution. Jarosite substituted by five oxyanions by 5 mol% was used in this study. The mineral phase change induced by reductive dissolution using ammonium oxalate was investigated, and the order of phase transition rate of jarosite to goethite was MoO₄-jarosite ≥ SeO₄-jarosite ≥ CrO₄-jarosite > pure jarosite > SeO₃-jarosite > AsO₄-jarosite, showing that the transition rates vary depending on the substituted oxyanion. The resultant concentration of the leached Fe was slightly different depending on the type of oxyanion and time but did not show a noticeable difference. The concentration of each oxyanion leached according to the change of the mineral phase showed that the order of concentration of oxyanions was Mo > Se(SeO₃) > As > Se(SeO₄) > Cr in general, and showed a slight increase with time. This trend was related to the species of oxyanions rather than mineral phase change. The results of this study showed that the phase transition of jarosite to goethite was affected by the species of oxyanions, but this tendency did not affect the concentrations leached oxyanions.

• Korean journal of applied entomology
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• v.61 no.2
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• pp.319-330
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• 2022

Andong is a place to culture the great amount of hot pepper (Capsicum annuum L.) in Korea. This study reports a yearly occurrence (March 31~October 25, 2021) of thrips infesting the hot pepper in Andong. Thrips caught to yellow sticky traps were diagnosed by morphological characters and showed two dominant species: Frankliniella occidentalis and F. intonsa. During this period, a total of 107,874 thrips were caught and included F. occidentalis at about 82%, F. intonsa at about 17%, and the other thrips at about 0.3%. There were two main peaks at May~June and at September~October, respectively, in which the total number of thrips was higher in the second peak and most were F. occidentalis. Interestinly, a low level of thrips occurred during July~August was observed and explained by their susceptibility to high temperatures. A laboratory experiment by exposing thrips to high temperatures showed that thrips were susceptible to temperatures higher than 35℃ and not tolerant to 45℃ for 1 h. Indeed, high temperatures higher than 45℃ were recorded in the greenhouses in Andong during July~August. F. occidentalis was more tolerant to the high temperatures than F. intonsa. On the other hand, the thrips showed the highest occurrence peak at July~August in hot pepper-culturing greenhouse in Kangwon, where the average temperatures were mostly lower than those of Andong and no high temperatures higher than 45℃ were recorded during July~August. A viral disease caused by tomato spotted wilt virus (TSWV) was observed in the hot peppers cultured in Andong greenhouses. Multiplex PCR was used to detect the virus along with identification of thrips. With a high record of about 30%, the virus-infected thrips were detected during all the monitoring period. The virulent thrips were identified to be only F. intonsa. These results suggest that F. occidentalis gives a direct damage especially during harvesting period with their high populations while F. intonsa gives indirect damage by transmitting TSWV.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.355-365
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• 2022

Precipitation and phase transition of iron minerals in mine drainage greatly affect the behavior of trace elements. However, the precipitation of ferrihydrite, one of the major iron minerals precipitated in drainage, and the related behavior of trace elements have hardly been studied. In this study, the effects of pH change and time on mineral precipitation characteristics in mine drainage from the Munkyeong coal mine were investigated, and the behavioral changes of trace elements related to the precipitation of these minerals were studied. In the case of precipitated mineral phases, goethite was observed at pH 4, and 2-line ferrihydrite mixed with small amount of 6-line ferrihydrite was mainly identified at pH 6 or higher. In addition, it was observed that the precipitation of calcite additionally increased as the pH increased in the samples at pH 6 or higher. The occurrence of goethite was probably due to the phase change of initially precipitated ferrihydrite within a short time under the influence of low pH. Our results showed that the concentration of trace elements was strongly influenced by pH and time. With increasing time, Fe concentration in the drainage showed a abrupt decrease due to the precipitation of iron minerals, and the concentration of As existing as oxyanions in the drainage, also decreased rapidly like Fe regardless of the pH values. This decrease in As concentration was mainly due to co-precipitation with ferrihydrite, and also partly to surface adsorption on goethite at low pH in drainage. Contrary to this observation, the concentration of other trace elements, such as Cd, Co, Zn, and Ni was greatly affected by the pH regardless of the mineral species. The lower the pH value, the higher the concentration of these trace elements were observed in the drainage, and vice versa at higher pH. These results indicate that the behavior of trace elements present as cations is more greatly affected by the mineral surface charge influenced by the pH values than the type of the precipitated mineral.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.429-438
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• 2022

This study evaluated the effect of the degree of weathering on the particle size distribution and the amount of fine particles generated in the aggregate production process during the crushing of igneous rock. Rock samples were collected from three areas with differences in strength from the Schmith hammer measurement at the aggregate quarry in Geochang, Gyeongsangbuk-do. After crushing with a jaw crusher under the same conditions in laboratory, particle size analysis, mineral analysis, chemical analysis, and weathering index were calculated. The Schmidt hammer measurements were 56, 28, and <10, and the CIA and CIW values of weathering index were also different, so the rock samples were classified into hard rock, soft rock, and weathered rock according to the weathering degree. It shows a smaller particle size distribution toward weathered rocks under the microscope, and the proportion of altered clay minerals such as sericite increased. The composition of feldspar and quartz was high for hard rock, and the ratio of muscovite and kaolinite was low. As a result of the crushing of the jaw crusher, hard rock produced a lot of coarse crushed material (13.2mm), while soft rock and weathered rock produced fine crushed material (4.75mm). The former showed the characteristics of the beta distribution curve, and the latter showed the bimodal distribution curve. The production of fine rock particles (based on 0.71mm of sieve, wt. %) increased to 13%<21%<22% in hard rock, soft rock, and weathered rock, and the greater the degree of weathering, the more fine rock particles were generated. The fine particles are recovered by the operation of the sand unit in the wet aggregate production process. Therefore, in order to minimize the amount of sludge generated in the aggregate production process, it was judged that a study on the optimal operation of cyclones could be necessary.

• 한국노년학
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• v.29 no.4
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• pp.1247-1259
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• 2009

Muscle mass is reduced by aging. There seems to be no direct relationship between sarcopenia(muscle loss) and medical cost in the elderly, but lowering muscle mass results in increase risk of fall and decrease of strength, fitness, physical activity, and independent life. This is coupled with physical trouble and chronic degenerative disease such as diabetes, obesity, hyperlipidemia, and hypertension. Thus, sarcopenia is potential risk factor increasing mortality. The purpose of this study was to investigate the effects of elastic band exercise and detraining on sarcopenia prevention related variables, body composition and fitness. The subject of this study was 60~70 aged 14 seniors who participated in exercise program in J-welfare senior center at J-gu in S-city. Elastic band exercise was performed twice per week for 12 weeks. The body composition and fitness variables were measured before 12 weeks of control, after control(before exercise), after 12 weeks of exercise(before detraining), and after 12 weeks of detraining. There was no significant difference in body composition and fitness variables before and after 12 weeks of control, but elastic band exercise before and after 12 weeks has effect on body composition variables such as weight (t=2.978, p=0.001), body mass index (t=3.502, p=0.004), percent body fat (t=2.216, p=0.045), muscle mass (t=-3.837, p=0.002), visceral fat area (t=5.186, p<0.001), and waist-hip ratio (t=3.045, p=0.009) and on fitness variables such as 2-minutes step (t=-6.891 p<0.001), arm curl (t=-4.702, p<0.001), chair stand (t=-4.860, p<0.001), chair sit and reach (t=-5.910, p<0.001), back scratch (t=-3.835, p=0.002), and 8-ft up and go (t=7.560, p<0.001). This exercise effect was continued after 12 weeks of detraining on body composition variables such as weight (t=2.323, p=0.037), body mass index (t=2.503, p=0.026), muscle mass (t=-3.137, p=0.008) and on fitness variables such as 2-minutes step (t=-6.489 p<0.001), chair stand (t=-4.694, p<0.001), chair sit and reach (t=-3.690, p=0.003), and 8-ft up and go (t=7.539, p<0.001). It was found that the elastic band exercise has positive effect on body composition and fitness in the elderly and the effect was maintained over 12 weeks of detraining.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.72-81
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• 2024

Purpose: This study aimed to assess the marginal and internal fit of 3-unit monolithic zirconia fixed partial dentures (FPDs) fabricated via computer-aided design and computer-aided manufacturing (CAD/CAM) from solid working casts and removable die system. Materials and Methods: The tooth preparation protocol for a zirconia crown was executed on the mandibular right first premolar and mandibular right first molar, with the creation of a reference cast featuring an absent mandibular right second premolar. The reference cast was duplicated using polyvinyl siloxane impression, from which 20 working casts were fabricated following typical dental laboratory procedures. For comparative analysis, 10 FPDs were produced from a removable die system (RD group) and the remaining 10 FPDs from the solid working casts (S group). The casts were digitized using a dental desktop scanner to establish virtual casts and design the FPDs using CAD. The definitive 3-unit monolithic zirconia FPDs were fabricated via a CAM milling process. The seated FPDs on the reference cast underwent digital evaluation for marginal and internal fit. The Mann-Whitney U test was applied for statistical comparison between the two groups (α = 0.05). Results: The RD group showed significantly higher discrepancies in fit for both premolars and molars compared to the S group (P < 0.05), particularly in terms of marginal and occlusal gaps. Color mapping also highlighted more significant deviations in the RD group, especially in the marginal and occlusal regions. Conclusion: The study found that the discrepancies in marginal and occlusal fits of 3-unit monolithic zirconia FPDs were primarily associated with those fabricated using the removable die system. This indicates the significant impact of the fabrication method on the accuracy of FPDs.