• Korean Journal of Environment and Ecology
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• v.20 no.4
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• pp.391-399
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• 2006

The population dynamics of Zacco koreanus in the upstream and downstream of Hoengseong Lake, Korea were investigated from April to October 2005. As the result of a comparison of variations regarding the time of I koreanus populations, it was confirmed that downstream was a place to remain compared to upstream Also the b value, assessed by Length-weight relationship in upstream and downstream, were $3.21{\sim}3.35,\;and\;2.94{\sim}3.37$, respectively indicating the fish in downstream had better than upstream. Additionaly condition factor(K) of each population in upstream and downstream were $0.0292{\sim}0.0693\;and\;-0.0165{\sim}0.0499$, respectively, K value in upstream lower than downstream. On the other hand, the maximum-growth value$(L_{\infty})$ calculated by von Bertalanffy's growth model in upstream and downstream were 279.7mm and 303.9mm, respectively, indicating that the potential-growth ability of population in downstream was higher than population in upstream. Therefore, Z. koreanus population in upstream became worse based on matters of age structure, Length-weight relationship, and von Bertalanffy's growth model. These results are considered to show the change of the physical environment by the constructing of Hoengseong Dam.

• Korean Journal of Environment and Ecology
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• v.27 no.4
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• pp.462-472
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• 2013

This study was carried out to provide a basic data for preservation of Pinus desiflora forest as cultural landscape forest by analyzing characteristics of plant community of P. desiflora forest in Geumjeongsan(mountatin) in Busan city. In order to analyze plant community of P. densiflora in Geumjeongsan, we set up 10 study plots inside and 8 plots outside of Geumjeongsansung(mountain fortress, hereinafter 'Sansung')(unit area: $400m^2$), a total of 18 plots. TWINSPAN analysis divided these 18 study plots into 6 communities which are Querqus serrata-P. desiflora community, P. desiflora community, P. desiflora-Q. serrata community, P. thunbergii-P. densiflora community, P. densiflora-P. thubergii-Q. acutissima community, and P. densiflora-Platycarya strobilacea community. Importance Percentage (I.P.) of each area and DBH class distribution of main species showed that P. densiflora community would succeed to Q. serrata community or C. tschonoskii community. Analysis on tree age found out that communities in the Sansung were 32~37 years old and those outside the Sansung were 44~57 years old. Shannon's species diversity index ranged from 0.4826 to 1.2499. Regarding correlation between species, P. densiflora had negative correlation with Styrax japonica. Based on abovementioned result we expected ecological succession from P. densiflora community to Q. serrata community inside of the Sansung. Outside the Sansung, succession from P. densiflora-P. thunbergii community to C. tschonoskii-Q. serrata community was expected. In order to manage P. densiflora forest as cultural landscape forest, Q. spp in the understory and shrub layer and deciduous broad-leaved arboreal trees should be managed. Tree crown management of deciduous broad-leaved trees in competition with P. desiflora, is also required.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.365-370
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• 2017

The flowering season of jujube (Zizyphus jujuba var. inermis (Bunge) Rehder) is overlaps with the rainy season and the abnormal weather conditions in Korea, thereby affecting pollination, fertilization, and fruit setting. We studied the pollinating activities of Apis mellifera L. and Bombus terrestris L. in rain shelter houses and their effects on fruit setting, with the ultimate aim of stabilizing fruit setting in Z. jujuba. A. mellifera and B. terrestirs were used for pollination in jujube orchard in the rain shelter house for approximately 55 days from June 1, 2016, to July 25, 2016. The peak time of the rate of outgoing and incoming A. mellifera was recorded in the afternoon. However, the diurnal activity of B. terrestris was constant between 09:30 and 17:30 h. The rate of jujube fruit set on current shoots by A. mellifera and B. terrestirs was 10.2 and 8.9%, whereas that in plots with no pollinators was 5.5%. Therefore, using pollinator in the rain shelter house in jujube orchard is effective in promoting jujube fruit setting.

• Journal of Korean Academy of Nursing Administration
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• v.20 no.4
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• pp.353-361
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• 2014

Purpose: The aim of this study was to compare job satisfaction, quality of life (QOL), incident report rate and overtime hours for 12-hour shifts and for 8-hour shifts in a pediatric intensive care unit (PICU). Methods: A descriptive survey was conducted with a convenience sample of 36 staff nurses from a PICU in a regional hospital in Korea. Data were collected using self-administrated questionnaires regarding job satisfaction and QOL at 6 months before and after the beginning of 12-hour shifts. Incident report rate and overtime hours for both 12-hour and 8-hour shifts were compared. Comparisons were made using $x^2$-test, paired t-test and Mann-Whitney U test. Results: After 12-hour shifts were initiated, job satisfaction significantly increased (t=3.93, p<.001) and QOL was higher for nurses on 12-hour shifts compared to 8-hour (t=7.83, p<.001). There was no statistically significant change in incident report rate ($x^2=0.15$, p=.720). The overtimes decreased from $36.3{\pm}34.7$ to $17.3{\pm}34.9$ minutes (Z=-8.91, p<.001). Conclusion: These results provide evidence that 12-hour shifts can be an effective ways of scheduling for staff nurses to increase job satisfaction and quality of life without increasing patient safety incidents or prolonged overtime work hours.

• Journal of agricultural medicine and community health
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• v.30 no.1
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• pp.113-120
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• 2005

Objectives: The worldwide epidemic of obesity is reporting but also in Korea. But there are few studies reporting with a community-based longitudinal data in Korea. This issues objects to measure the prevalence and evaluate the trends of overweight based on the repeated cross-sectional studies at a rural community adults during 10 years. Methods: With 1990~1999 Yang-Pyeong Cohort Baseline Survey Dataset, BMI is calculated and Overweight is categorized according to the classification of overweight in adult by Korean Society for the Study of Obesity. Results and Conclusions: Crude BMI means at 1990 is estimated to $22.0Kg/m^2$ and at 1999, $24.4Kg/m^2$(p for trend<0.0001). Trends of age adjusted BMI has borderline significant, but that of Age and Sex adjusted BMI is statistically significant(p for trend=0.039). In male population the change of the overweight prevalence from 1990 to 1999 is 35%, and in female population the change is 21.9%(Z=0.55). Female has more increased prevalence than male, but the change is more dominant in male than in female. At a rural community, obesity has markedly been increasing during the past decade and female in a rural community has higher prevalence of overweight.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.199-207
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• 2008

Wavelength converting devices with a ridge-type waveguide in periodically poled $MgO:LiNbO_3$ are made and characterized. The experimental results are compared with theoretical analysis on the effects of waveguide dimension and duty ratio of the periodically poled structure. To show the relationship of the conversion efficiency to those factors, a new measurement system is configured. That experimental results show that the center wavelength, normalized conversion efficiency and full width half maximum of the conversion efficiency curve are 1067.45 nm, 90.7%/$Wcm^2$ and 0.17 nm, respectively. Also, the estimated results of the duty period and full width half maximum of the conversion efficiency from theoretical calculations agreed well with experimental results with the errors of 0.016 ${\mu}m$ and 0.01 nm.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2379-2386
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• 2020

This paper presents the results of the first intercomparison exercise performed by the Korea retrospective dosimetry (KREDOS) working group using electron paramagnetic resonance (EPR) spectroscopy. The intercomparison employed the alanine dosimeter, which is commonly used as the standard dosimeter in EPR methods. Four laboratories participated in the dose assessment of blind samples, and one laboratory carried out irradiation of blind samples. Two types of alanine dosimeters (Bruker and Magnettech) with different geometries were used. Both dosimeters were blindly irradiated at three dose levels (0.60, 2.70, and 8.00 Gy) and four samples per dose were distributed to the participating laboratories. Assessments of blind doses by the laboratories were performed using their own measurement protocols. One laboratory did not participate in the measurements of Magnettech alanine dosimeter samples. Intercomparison results were analyzed by calculating the relative bias, E_n value, and z-score. The results reported by participating laboratories were overall satisfactory for doses of 2.70 and 8.00 Gy but were considerably overestimated with a relative bias range of 10-95% for 0.60 Gy, which is lower than the minimum detectable dose (MDD) of the alanine dosimeter. After the first intercomparison, participating laboratories are working to improve their alanine-EPR dosimetry systems through continuous meetings and are preparing a second intercomparison exercise for other materials.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.1
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• pp.18-23
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• 2016

It is important to design photobioreactor by cheap material for economical microalgal biomass production. In this study, two types of marine photobioreactors (MPBR), made by either polyvinyl chloride (MPBR-PVC) or high density poly ethylene (MPBR-HDPE), are used and performance of these were compared. Tetraselmis sp. KCTC 12236BP is a green marine alga that isolated from Ganghwa Island, Korea, and the strain was used for marine cultivations using MPBR-PVC and MPBR-HDPE. The cultivations were performed three times in the spring season of 2012 using MPBR-PVC and of 2013 using MPBR-HDPE in the coastal area of Young Heung Island. As the results, MPBR-PVC shows higher biomass productivities than MPBR-HDPE, due to its high light transmittance. In the cultivations using MPBR-PVC, the average sea water temperature was $11.5^{\circ}C$ during the first experiment and $16.5^{\circ}C$ during the second and third experiments. Average light intensities during three times for experiments were 407.5, 268.1 and $273.0{\mu}{\cdot}E{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. The maximum fresh cell weight and average biomass productivity were $1.2g{\cdot}L^{-1}$ and $0.12g{\cdot}L^{-1}{\cdot}day^{-1}$. These results showed that Tetraselmis sp. KCTC12236BP were adapted well with the environmental conditions from ocean, and grow in the MPBR-PVC and MPBR-HDPE.

• Journal of Ecology and Environment
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• v.29 no.6
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• pp.565-572
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• 2006

This study examined the decomposition of blades and culms of aquatic emergent plant species, Zizania latifolia, Phragmites communis and Typha angustata, which were the most frequent in Lake Paldang. The experiment was carried out from July to December, 2005 in fresh water of lake Paldang using litter bag method. The litter bags had 1.2 mm mesh size and were suspended at 1 m depth of water surface. Remaining mass of blades and culms of each species after 97 days was 21.2% and 22.6% of initial mass in Z. latifolia, 32.5% and 56.4% in P. communis and 44.7% and 38.1 % in T. angustata, respectively. The plant tissue having high N concentration and low C/N exhibited the faster decay rate than the others. However, the tissue of high content of lignin, cellulose, lignin:N, and cullulose:N showed a slow decomposition rate. Water temperature was the most effective environmental factor on the emergent macrophyte litter decomposition in aquatic ecosystems. According to the water temperature, DO, $NO_3^-$-N, and total phosphate concentration were changed in the linear way. The mass loss of plant tissue of emergent macrophytes showed positive relationship with P concentration in water. The experiments on the decomposition of the litter using different mesh sized litter bag did not show significant differences between them. The results suggest that the decomposition of emergent macrophytes in fresh water of lake Paldang, which showed features of lentic and lower part of a stream, was affected by microbial activities better than the micro-invertebrates such as shredders.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.477-483
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• 2009

The purpose of this study was to compare the microleakage of low and high viscosity flowable resins in class V cavities applied with 1-step adhesives. Forty Class V cavities were prepared on the cervices of buccal and lingual surfaces of extracted molar teeth and divided into four groups (n=8). Cavities were restored with AQ Bond Plus /Metafil Flo $\alpha$, G-Bond/ UniFil LoFlo Plus (Low flow groups), AQ Bond Plus/Metafil Flo and G-Bond/UniFil Flow (High flow group), respectively. Specimens were immersed in a 2% methylene blue solution for 24 hours, and bisected longitudinally. They were observed microleakages at the enamel and dentinal margins. In conclusion, the low viscosity flowable resins showed lower marginal microleakage than do the high vis cosity flowable resins in class V cavities.