• Environmental Analysis Health and Toxicology
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• v.22 no.4
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• pp.329-337
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• 2007

This study considers the characteristics of nitrogen dioxide ($NO_2$), ozone ($NO_3$) and sulfur dioxide ($SO_2$) in three cities of Daegu-Gyeongbuk Area (Daegu, Pohang, and Gumi), which have different city or industrial characteristics, over a time period of 2 years. The diurnal, weekly, monthly and seasonal concentration variations of criteria air pollutants were attributed to compounds or city types. However, the seasonal variations of $O_3$ concentrations were dependent on compounds, but not on city types. Lower $O_3$ concentrations were observed in July when comparing with other summer months. For $SO_2$ and $NO_2$, the concentrations were higher in Daegu when compared to Pohang and Gumi, while the concentrations of $O_3$ were higher in Pohang and Gumi. $SO_2$ exhibited higher levels in the morning hours, while $O_3\;and\;NO_2$ exhibited higher levels in the afternoon hours for all cities. For $O_3$, the concentrations observed during Sunday were higher than those of other week or weekend days. Furthermore, the monthly and seasonal concentration variations of air pollutants depended on compounds or city types. It if noteworthy that the current monthly and seasonal variations were consistent with several prey ious studies.

• Journal of Environmental Science International
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• v.16 no.10
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• pp.1157-1167
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• 2007

In an effort to interpret the characteristics of fine particle concentrations in Busan, time variations of hourly monitored concentrations $PM_{10}$ (Particulate Matter with aerodynamic Diameter ${\le}10\;{\mu}m$) in Busan are analyzed for the period from 2000 to 2005. The characteristics of aerosol second generation formation process is also interpreted qualitatively, by using the statistical analysis of the meteorological variables including temperature, wind speed, and relative humidity. The result shows some significant annual, seasonal, weekly and diurnal variations of $PM_{10}$ concentrations. In particular, seasonal(i.e., spring) variations are governed by frequency of yellow sand events even for the non-yellow sand cases where yellow-sand days are eliminated in our analysis. However, in seasonal variation, summer season predominate lower $PM_{10}$ concentrations due to the frequent precipitation, and weekly and diurnal variations are both found to be reflecting the emission rate from traffic amount. Correlation coefficients between $PM_{10}$ concentration and meterological variables for non-yellow sand days show overall negative correlation with visibility, wind speed, cloud amounts, and relative humidity. However for non-precipitation days, during non-yellow sand period positive correlation are found clearly with relative humidity, suggesting the importance of secondary aerosol formation in Busan that can be achieved by both homogeneous aerosol formation and heterogeneous transformations resulting from hygroscopic aerosol characteristics.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.95-104
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• 2000

In order to elucidate chatracteristics of water quality and seasonal dynamics of phytoplankton community in Kyungpo lake, the weekly variation of algal population and 11 environmental factors were investigated from March 1998 to February 1999. A total 121 species of phytoplankton belonged to 57 genera, 4 genera 7 species of the Euglenophyceae, 1 genera 2 species of the Chrysophyceae, 2 genera 3 species of the Cryptophyceae, 1 genera 1 species of the Dinophyceae, 6 genera 9 species of the Cyanophyceae, 28 genera 78 species of the Bacillario-phyceae and 15 genera 21 species of the Chlorophyceae, was identified. Cryptomonas sp., Chamydomonas sp., Nitzschia frustulum, Oscillatoria sp., Lyngbya sp, and Dictyosphaerium pulchellum occurred successively as dominant phytoplankton species from March 1998 to February 1999. Density of phytoplankton cell number showed the peak in early April when Chlamydomoas sp. was dominated. The diversity index of phytoplankton community showed low values in the dominating period of Cryptomonas sp. and Chlamydomonas sp. The concentration of chlorophyll a fluctuated between 1.09 and 107.7$\mu\textrm{g}$ㆍ1$^{-1}$. Water temperature, salinity, DO, conduc tivity and SS were ranged 0.5-27.8$^{\circ}C$, 2.8-25.2 ppt, 4.62-19.21 mgO$_2$ㆍ1$^{-1}$, 5.33-34.76 mS/cm and 0.017-0.184 mgㆍ1$^{-1}$, respectively. Annual means of Secchi disc transparency was 36cm and thai of pH value was 8.5. The concentrations of PO$_4$-P was ranged 0.0012-0.077 mgㆍ1$^{-1}$ , and showed high value from August to October. The concentrations of NO$_2$-N, NO$_3$-N and NH$_4$-N was ranged 0.0011-0.1 mgㆍ1$^{-1}$, 0.074-3.33mgㆍ1$^{-1}$ and 0.0024-0.259 mgㆍ1$^{-1}$, respectively. Among environmental factors, water temperature was negatively correlated with DO, salinity and conductivity, DO was positively correlated with salinity and conductivity. Chlorophyll a, one of the indicies of eutropication in lake, was negatively correlated with NH$_4$-N. The cell density of Cryptomonas sp., which was the most dominant species in this lake, was negatively correlated with transparency. [Kyoungpo lake, Phytoplankton, Cryptomonas sp. , Chlamydomonas sp., Seasonal variation].

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.2
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• pp.55-71
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• 1989

This study was carried out to determine the ozone concentration to behaviour and the factors to be influenced the variation of its concentration in the ambient air in Seoul. Measurements of ozone concentrations were made at 10 monitoring station to take care of SIHE (Seoul Institute of Health & Environment) during December 1987 to November 1988, also measured the hourly average concentration of sulfur dioxide, total suspended particulate, nitrogen oxide $(NO & NO_2)$, carbon monoxide, hydro carbon $(n-CH_4 & THC)$ and meteorological factors, that is, temperature, humidity, wind velocity wind direction and ultraviolet intensity etc, for the same period at same place. The basis of the data obtained were analyzed statistically along with the various data. The results were as follows; 1. The annually arithmetic mean concentration of ozone for the 10 sites during one years was 10.0 ppb and ranged from 3.1 $\pm$ 4.5ppb at the Kuro industrial complex to 17.2 $\pm$ 18.7 ppb at the Ssangmun site. 2. The frequency of hours on which oxidant concentrations exceeded the present short term standard of ozone (100 ppb) were 78 times. 3. The diurnal patterns of hourly ozone concentrations in Seoul area was a typical bi-modal variation which have 4 to 5 a.m. peak and 3. to 4 p.m peak. 4. The time ozone of highest ozone concentration in a whole day and hight was 1 to 5 p.m and 90.9 percent of appearence rate. 5. The diurnal patterns of hourly ozone concentrations in Seoul were on the whole the order of daytime from 5.8ppb to 28.7 ppb evening from 1.7 to 18.7 ppb night time from 1.9 to 9.3 ppb daybreak from 1.4ppb according to measuring sites, and the highest that observed at the Ssangmun area while the lowest was the Kuro industrial complex monitor sites. 6. The weekly variation of ozone concentration was the higher level ozone concentration in the day of the week occured sunday-monday and weekend but the decrease were observed from wednesday to thursday.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.71-78
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• 2021

Purpose: To evaluate the inter-fractional position and respiratory reproducibility of lung and liver tumors using pressure conserving type(P-type) abdominal compressor in volumetric modulated arc therapy(VMAT). Materials and methods: Six lung cancer patients and three liver cancer patients who underwent VMAT using a P-type abdominal compressor were included in this study. Cone-beam computed tomography(CBCT) images were acquired before each treatment and compared with planning CT images to evaluate the inter-fractional position reproducibility. The position variation was defined as the difference of position shift values between target matching and bone matching. 4-dimensional cone-beam computed tomography(4D CBCT) images were acquired weekly before treatment and compared with planning 4DCT images to evaluate the inter-fractional respiratory reproducibility. The respiratory variation was calculated by the magnitude of excursions by breathing. Results: The mean ± standard deviation(SD) of overall position variation values, 3D vector in the three translational directions were 1.1 ± 1.4 mm and 4.5 ± 2.8 mm for the lung and liver, respectively. The mean ± SD of respiratory variation values were 0.7 ± 3.4 mm (p = 0.195) in the lung and 3.6 ± 2.6 mm (p < 0.05) in the liver. Conclusion: The use of P-type compressor in lung and liver VMAT was effective for stable control of inter-fractional position and respiratory variation by reproduction of abdominal compression. Appropriate PTV margin must be considered in treatment planning, and image guidance before each treatment are required in order to obtain more stable reproducibility

• Journal of Preventive Medicine and Public Health
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• v.37 no.2
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• pp.182-189
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• 2004

Objectives : The objective of this study is to compare the circadian patterns of heart rate variability assessed by 24-hour ambulatory electrocardiographic (ECG) recordings during day shift and night shift among the workers in the 5 days-concecutive-12-hour shift in an automobile factory in Korea. Methods : The study population consisted 300 workers, who were randomly selected among the 8700 total workers in one car factory. To analyse circadian variation, the 24-hour ECG recordings (Marquette) were measured during day shift (08:00-20:00 h) and night shift (20:00-08:00 h). Analysis was performed for all time and frequency domain measures of HRV. 233 workers completed taking 24-hour ECG recordings. Results : This study shows that the 24 hourcircadian variation mainly follows work/sleep cycle rather than day/night cycle among shift workers. This study also shows that among the night shift, the circadian variation between work and sleep cycle decreased compared to the work/sleep cycle among day shift workers. All time and frequency domain parameters (except LF/HF ratio) show significantly different between work and sleep in the day shift and night shift. Conclusion : These changes in heart rate variability circadian rhythms reflect significant reductions in cardiac parasympathetic activity with the most marked reduction in normal vagal activity among the shift workers. Especially, it suggests the circadian rhytm has blunted among the night workers. The quantification of the circadian variation in HRV can be a surrogates of workers' potential health risk, as well as suggests possible mechanisms through which the shift works compromise workers' health.

• Journal of Crop Science and Biotechnology
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• v.11 no.1
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• pp.23-30
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• 2008

The relationship between three phenological parameters and somatic embryogenesis was investigated during a two-year period. Staminodes and petals from six hybrids and two clones as controls were sowed on three distinct primary callus growth media. Flowering level, fructification level, and leaf thrusts rhythm as phenological parameters were measured simultaneously during the weekly harvest of flower buds. Mean and coefficient of variation of the measured parameters highlighted stable phenological phases. The relationship between phenological parameters and somatic embryogenesis was investigated first by comparing the variation of somatic embryogenesis and that of the phenological parameters, and second by using Pearson's linear correlation. Except for the fructification level in both control clones the first year, the other parameters recorded stable phenological phases, regardless of the genotype and year. Favorable and unfavorable phases for the somatic embryogenesis were identified. In hybrids, favorable phases included February, August, September, and October. In both control clones, time interval propitious to embryogenesis stretched from February to December. The significance of the coefficient of correlation seemed to establish a relationship between somatic embryogenesis and phenology. However, a causal link could not be established. Leaf thrusts rhythm was revealed to be the phenological parameter most linked to somatic embryogenesis. Attempts to optimize embryogenesis during unfavorable phases, showed that a correction of 2.4 D/TDZ concentration is not the solution.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.544-561
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• 2004

Weekly monitoring of discharge and water quality in forested and agricultural subcatchments were performed to understand the difference of water quality caused by land uses in Doegwollyong area. Correlations between water quality variables including discharge were analyzed for the same purpose. There was little variation of water Quality in forested subcatchment. On the other hand, the range of water quality variation in agricultural subcatchment was wide due to soil loss and the application of chemical fertilizers and livestock manure. Dissolved oxygen(DO) had strong negative correlation with discharge in both subcatchments. Total nitrogen(T-N) and potassium ion(K$^{+}$) had stronger positive correlation with discharge in forested subacatchment than in agricultural one. On the other hand, total suspended sediments(TSS), total phosphorus(T-P), and chemical oxygen demand(COD) had stronger correlation with discharge in agricultural subcatchment than in forested one. As water pollution of the Doam Lake, especially the increase of T-P is serious, soil conservation is very important to improve water quality. In particular, the loss of soil and nutrients from late June till early July were more serious than any other seasons, therefore it is necessary to apply environmentally sustainable methods of cultivation.n.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.5
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• pp.423-433
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• 2014

This study examined the short-term variability of $CO_2$ concentrations measured at the Gosan site ($33^{\circ}17^{\prime}N$, $126^{\circ}10^{\prime}E$) in Jeju, Korea for the last 9 years from 2002 to 2010. The weekly distribution shows higher $CO_2$ concentrations during weekends than weekdays which implies the impact of local emissions because Jeju Island is one of the top tourist attraction in Korea. In diurnal variation, $CO_2$ concentration reached the maximum at 6 am and the minimum at 1 pm. The high $CO_2$ concentrations were mostly associated with lower wind speed (below 4 m/s) and easterlies, which was typical of summer night. In other seasons, however, the high concentrations were encountered under strong westerlies (8~16 m/s), which implies the influence of Chinese outflows. $CO_2$ concentrations were found to be highly correlated with meteorological parameters including wind speed, temperature, humidity, and solar radiation except for winter.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.149-157
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• 2023

Purpose : Genu varum is a condition characterized by a wider than normal gap between. This may be due to muscle weakness caused by poor posture, lifestyle, or lack of exercise. This study aimed to compare the effects of ball-based squats and narrow squats on muscle thickness, Q-angle, and the gap between the knees, in order to assess the potential for improving this condition. Methods : Twenty six adult participants with genu varum were randomly assigned to either a ball-based squat group (n=13) or a narrow squats group (n=13). Both groups performed their respective exercises three times weekly for 4 weeks. The data was analyzed using paired t-tests to compare pre- and post- intervention measurements within each group, and independent t-test was used to compare the two groups. Results : Both groups showed significant improvement in the thickness of the vastus lateralis and medialis, and rectus femoris muscles, as well as a significant decrease in the gap between the knees (p<.05). However, there was no significant difference in Q-angle variation between the two group. Furthermore, there was no significant differences in the Q-angle, gap between the knees, and muscle thickness variation between both groups. Conclusion : The results suggest that both ball-based squats and narrow squats are effective in improving muscle thickness and reducing the gap between the knees in adults with genu varum. However, there was no significant difference between the two types of squats in terms of their effects on the Q-angle. These findings highlight the potential for exercise interventions to address this common postural issue.