• Publications of The Korean Astronomical Society
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• v.23 no.1
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• pp.1-12
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• 2008

Understanding of the basic characteristics of an astronomical instrument is a prerequisite to obtaining reliable data from the instrument. We have analyzed more than 1,000 calibration images from the Fairchild 486 CCD (hereafter the Maidanak 4k CCD system) attached to the AZT-22 1.5m telescope at Maidanak Astronomical Observatory in Uzbekistan. The Maidanak 4k CCD system supports three readout modes through 1, 2, or 4 amplifiers. In most cases observers use 4-amplifier readout mode to save time. We have tested the stability and seasonal variation of zero levels and confirm that two quadrants of the images (Amp 1 & 2) show no appreciable seasonal variation. but the other two quadrants (Amp 3 & Amp 4) show an evident seasonal variation in the bias level. The Cryo Tiger, the cooling system used at the Maidanak 4k CCD system, maintains the CCD temperature at -108'E, and effectively suppresses the dark electrons. The mean value versus the variance plot of the flat images does not show the expected relation for an ideal Poisson noise distribution and this is attributed to the large variation in quantum efficiency between different pixels. In addition, we confirm that there is no appreciable difference in gain between readout amplifiers, but there is a large variation in quantum efficiency across CCD chip especially in U. Due to the finite length of shutter opening and closing time, the effective exposure time varies across the science images. We introduce two parameters to quantify the effect of this uneven illumination and present a method to remove these effects. We also present a method to remove the interference patterns appearing in the images obtained with longer wavelength filters and investigate the spatial variation of the point spread function.

• Korean journal of applied entomology
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• v.34 no.2
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• pp.106-111
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• 1995

This study was carried out to investigate the effect of mass trapping with synthetic sex pheromone on seasonal occurrence of, the Beet amyworm (BAW) Spodoptera exigua, and on suppress of their density in Chonnam province from 1992 to 1994. Adult males of BAW were colllected by the trap from early through early November. The numbers began to increase abruptly from early July, and forming three peaks on mid July, early August and early September. Yearly occurrence and the area damaged by the BAW varied in relation to weather condition. Especially, low temperature and heavy rainfall in August 1993 seems to have affected to reduce the BAW population. The pheromone trap attracted higher numbers (1.5~2.3 times) of BAW adult than ordinary light rap. And the BAW population in vinyl hose was noticeably reduced when more than 10 pheromone traps were operated per 330$\m^2$ of vinyl house.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.37-43
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• 1985

The present investigations were carried out for the purpose of making clear the fundamental features of the compositional difference of agarose and agaropectin in agar prepared from Gellidium amansii collected in different places and seasons, and its effect on properties of agar. The samples, Gellidium amansii, was collected every month from the same locality on the coast of the Ilgwang-myon, Yangsan-gun, Kyongnam, from March 1982 to February 1983. In addition, agarose and agaropectin in agar were isolated by dimethyl sulfoxide. The results obtained were summarized as follows : 1. In seasonal variation, the maximum yield of agar noted from spring through summer, and the minimum in February. 2. The experiment showed that the agarose and agaropectin composition in agar was changed, even if the seaweed collected from the same season was used as raw material. Seasonal variation of agarose and agaropectin contents in agar, the highest content occurred in August, $76.2\%$, and the lowest in January, $50.1%$. 3. Jelly strength, gelation ability of agar tended to increase as the agarose content was risen, but sulfate content was decreased.

• Korean Journal of Clinical Pharmacy
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• v.8 no.2
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• pp.89-94
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• 1998

Seasonal rhythmic changes in gentamicin pharmacokinetics was evaluated in 10 healthy male volunteers after single intravenous 80 mg administration of gentamicin at 9:00 a.m. during summer and winter. The mean terminal half-life and AUC of gentamicin were $3.56\pm0.14\;hr\;and\;25.03\pm2.84\;{\mu}g/ml{\cdot}hr$ in winter and $3.08\pm0.41\;hr\;and\;21.84\pm2.51\;{\mu}g/ml{\cdot}hr$ in summer. The mean total body clearance $(CL_t)$ and elimination rate constant $(k_{10})$ of gentamicin was $3.17\pm0.43\;L/hr,\;0.458\pm0.06\;hr^{-1}\;in\;winter\;and\;3.66\pm0.45\;L/hr,\;0.561\pm0.07\;hr^{-1}$ in summer, The mean volumn of distribution $(V_{dss})$ of gentamicin at steady state was $12.65\pm1.09$L in winter and $12.39\pm1.25$ L in summer. Serum concentrations of gentamicin in winter were increased significantly during 4-8 hr (p<0.05) compared to those of gentamicin in summer. The elimination rate constant $(k_{10})$ of gentamicin in winter was decreased significantly $(p<0.05)$ compared to that of gentamicin in summer. The mean volume of distribution at steady state $(V_{dss})$, AUC, mean total body clearance ($CL_t$) and terminal half-life of gentamicin in the winter were increased but were not significant. The mean intrasubject fluctuations in terminal half-life, AUC and $CL_t$ between winter and summer were 8.2, 11.0 and $6.0\%$ respectively.

• Journal of Korea Water Resources Association
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• v.32 no.4
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• pp.501-510
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• 1999

Stream and groundwater qualities of small agricultural watershed in Kangwon Probince, Korea were monitored 1 to 2 years, and the relationships between stream and groundwater qualities and seasonal water quality changes analyzed. Flooded paddy fields influenced groundwater level and quality during rice culture. The differences between groundwater levels during rice culture and non-culture spans were between 0.8 and 2.91 m. Seasonal changes of total nitrogen and nitrate nitrogen concentrations of stream and groundwater were very similar and groundwater quality was thought to have a profound impact on stream quality of the research watersheds. Suspended solids and BOD maintained the first degree stream water quality throughout the monitoring period except for a few and short flooding spans. The concentrations of total phosphorus and total bacteria of both waters showed wide variations and any seasonal trends were not observed. Long-term monitoring studies on small rural watersheds were recommended to understand the pattern of both stream and groundwater quality changes with respect to land use, season and cultural practice, and to apply the results to develop effective water quality management policies for large river and domestic water supply systems.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.6
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• pp.382-390
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• 2015

To simulate a complicated hydrodynamic phenomena in the surf zone, the SWASH model is used in Haeundae Beach. The SWASH model is well known as a model competing with the Boussinesq-type model in terms of near shore waves and wave-induced currents modelling. This study is aimed to the detailed analysis of seasonal waves and wave-induced current simulation in Haeundae Beach, where the representative seasonal wave conditions was obtained from hourly measured wave data in 2014 by Korea Hydrographic and Oceanographic Administration( KHOA). Incident wave conditions were given as irregular waves by JONSWAP spectrum. The calculated seasonal wave-induced current patterns were compared with the field observation data. In summer season, a dominant longshore current toward the east of the beach appears due to the effect of incident waves from the South and the bottom bathymetry, then some rip currents occurs at the central part of the beach. In the winter season, ESE incident waves generates a strong westward longshore currents. However, a weak eastward longshore currents appears at the restricted east side areas of the beach.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.439-447
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• 2019

Some dynamical issues about the Tsushima Warm Current (TWC) are reviewed and checked for the remaining unresolved problems, focusing on the formation of the TWC, seasonal variation of its volume transport and its branching in the East Sea. The TWC is a part of the North Pacific (NP) subtropical gyre driven by the NP global wind system. However, the quantitative amount of volume transport is sensitive to friction, basin geometry, barrier effect and so on. Among many causes suggested by many scientists, subpolar winds are found to be most closely related with the seasonal variation of TWC volume transport. However, more studies relating the latter not only to the subpolar winds but also to those including the subtropical winds seem to be required. The branching of the TWC has been known to be due to the western intensification for the East Korean Warm Current (EKWC) and to the bottom trapping for the Nearshore Branch. Since the former hypothesis is problematic in explaining the seasonal variation of the EKWC, other candidate mechanisms may need to be considered.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.24 no.2
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• pp.207-217
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• 2021

Purpose: This study aimed to investigate the seasonal changes in vitamin D levels in a healthy pediatric population living in mid-latitude East Asian urban areas. Methods: A pediatric population was selected from single secondary hospital visitors. Clinical data and serum vitamin D levels were collected retrospectively. Statistical analyses were performed based on the month of the blood sampling date, subject age, and vitamin D supplementation history. The data were categorized into three subgroups based on serum vitamin D levels-adequate (≥30 ng/mL), insufficient (20-29 ng/mL), and deficient (<20 ng/mL). Results: Of the 481 patients, 172 had vitamin D supplementation history. More than 70% of the total study population had inadequate vitamin D levels (<30 ng/mL). The non-supplemented group and the supplemented group showed significantly uneven monthly distribution of the adequate, insufficient, and deficient subgroups. Only the non-supplemented group showed significantly different average vitamin D levels in the summer months compared to the winter months. In the non-supplemented group, vitamin D levels were the lowest in March, the highest in August and September. Significant relevance was noted between vitamin D supplementation status and vitamin D serum level in February and March. There was no significant difference between different age groups in terms of the distribution of vitamin D levels. Conclusion: Currently-widespread vitamin D replacement methods seem to have some effect on increasing the overall serum vitamin D levels, specifically during late winter when natural serum vitamin D levels plunge. However, they are unable to fully compensate the seasonal fluctuation.

• Journal of Animal Reproduction and Biotechnology
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• v.36 no.4
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• pp.261-269
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• 2021

Because sows are industrially vital for swine production, monitoring for their health or disorder status is important to ensure high reproductive performance. Especially, ambient temperature changes in different season, especially during summer, are directly influenced to the reproductive performance of sows. Although the serum biochemical parameters are widely applied in the veterinary medicine with wide ranges for the physiological process, the values are also influenced by several factors such as age, breed, gender, and stress. In addition, domestic sows in Korea-specific reference interval (RI) for serum biochemistry has not been established yet. Therefore, the present study was aimed to evaluate seasonal variation of RIs in the serum biochemistry in domestic sows in Korea at different seasons and to establish normal RIs using a RI finding program (Reference Value Advisor). Significant difference (p < 0.05) on the different seasons were identified in several serum biochemical parameters including BUN, CRE, GGT, GLU, ALB, TP, LDH and Na in sows. Therefore, we further established RIs, specific in domestic sows in Korea regardless of season. The established RIs based on the serum biochemical values provide a baseline for interpreting biochemical results in the domestic sows in Korea, regardless of seasonal effect. It may contribute to develop a strategy for better reproductive performance by improving breeding management practice and evaluating health of pig herds, which facilitate to avert the economic loss in summer infertility in sows.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.54-65
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• 2023

Effect of environmental factors on the seasonal variations of zooplankton communities was investigated in the semi-closed Yeoja Bay, Korea from February, April to August, and November 2021. Out of a total 49 species of zooplankton were collected with a predominant of neritic copepods (mainly Paracalanus orientalis, Acartia omorii, Acartia ohtsukai, Centropages abdominalis, Ditrichocorycaeus affinis, and Oithona sp.), accounting for 58.9% of the total abundance of zooplankton. The diversity indices indicated a relatively highest in July, suggesting that diversity is influenced by seasonal temperature, N. scintillans, and neritic copepods species. A cluster analysis with non-metric multidimensional scaling revealed four groups of zooplankton communities. The February sample clustered into Group A, having the lowest mean total abundance and species diversity of zooplankton, consisting mainly of N. scintillans located the whole region. Cluster Group B from the spring season (April to May) and contained the species diversity with some neritic copepods. Cluster Group C from the summer season (June to August) mainly comprised P. orientalis, A. ohtsukai, Oithona sp., and hydromedusae. Cluster Group D from the autumn season (November) mainly comprised P. orientalis, Temora discaudata. Redundancy analysis indicated that abundance is positively correlated with temperature, salinity, and pico chlorophyll-a concentrations. This study showed that planktonic larvae (such as branchyura larvae) and some copepods (including A. omorii, A. ohtsukai, C. sinicus, and C. abdominalis) were significantly vulnerable to zooplankton community of temperature, salinity, and pico chlorophyll-a concentrations.