• Atmosphere
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• v.31 no.1
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• pp.29-43
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• 2021

In this study, two-step statistical approach including Principal Component Analysis (PCA) and Multiple Linear Regression (MLR) was employed, and main meteorological factors explaining the high-PM2.5 episodes were identified in two regions: Seoul and Busan. We first performed PCA to isolate the Principal Component (PC) that is linear combination of the meteorological variables observed at two levels: surface and 850 hPa level. The employed variables at surface are: temperature (T2m), wind speed, sea level pressure, south-north and west-east wind component and those at 850 hPa upper level variables are: south-north (v850) and west-east (u850) wind component and vertical stability. Secondly we carried out MLR analysis and verified the relationships between PM2.5 daily mean concentration and meteorological PCs. Our two-step statistical approach revealed that in Seoul, dominant factors for influencing the high PM2.5 days are mainly composed of upper wind characteristics in winter including positive u850 and negative v850, indicating that continental (or Siberian) anticyclone had a strong influence. In Busan, however, the dominant factors in explanaining in high PM2.5 concentrations were associated with high T2m and negative u850 in summer. This is suggesting that marine anticyclone had a considerable effect on Busan's high PM2.5 with high temperature which is relevant to the vigorous photochemical secondary generation. Our results of both differences and similarities between two regions derived from only statistical approaches imply the high-PM2.5 episodes in Korea show their own unique characteristics and seasonality which are mostly explainable by two layer (surface and upper) mesoscale meteorological variables.

• Steel and Composite Structures
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• v.47 no.2
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• pp.217-238
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• 2023

In this study, a parametric study was performed considering material properties of concrete, material properties of steel, the number of longitudinal reinforcement (reinforcement ratio), CFRP ply orientations, a number of layers as variables by using ABAQUS. Firstly, the parameters used in the Hashin failure criteria were verified using four coupon tests of CFRP. Secondly, the numerical models of the beams strengthened by CFRP were verified using five experimental data. Finally, eighty numerical models and eighty analytic calculations were developed to investigate the effects of the aforementioned variables. The results revealed that in the case of using fibrous polymer to prevent shear failure, the variables related to reinforced concrete significantly affected the behavior of specimens, whereas the variables related to CFRP composite have a slight effect on the behavior of the specimens. As a result of numerical analysis, while the increase in the longitudinal tensile and compression reinforcement, load bearing capacity increases between 23.6%-70.7% and 5.6%-12.2%, respectively. Increase in compressive strength (29 MPa to 35 MPa) leads to a slight increase in the load-carrying capacity of the specimens between 4.6% and 7.2%. However, the decrease in the compressive strength (29 MPa to 20 MPa) significantly affected (between 6.4% and 8.1% decrease observed) the behavior of the specimens. As the yield strength increases or decreases, the capacity of specimens increase approximately 27.1% or decrease 12.1%. The effects of CFRP ply orientation results have been obtained as a negligible well approximately 3.7% difference. An increasing number of CFRP layers leads to almost no effect (approximately 2.8%) on the behavior of the specimen. Finally, according to the numerical analysis, the ductility values obtained between 4.0 and 6.9 indicate that the beams have sufficient ductility capacity.

• Journal of Astronomy and Space Sciences
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• v.36 no.4
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• pp.283-292
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• 2019

The purpose of this study was to develop a period analysis algorithm for detecting new variable stars in the time-series data observed by charge coupled device (CCD). We used the data from a variable star monitoring program of the CBNUO. The R filter data of some magnetic cataclysmic variables observed for more than 20 days were chosen to achieve good statistical results. World Coordinate System (WCS) Tools was used to correct the rotation of the observed images and assign the same IDs to the stars included in the analyzed areas. The developed algorithm was applied to the data of DO Dra, TT Ari, RXSJ1803, and MU Cam. In these fields, we found 13 variable stars, five of which were new variable stars not previously reported. Our period analysis algorithm were tested in the case of observation data mixed with various fields of view because the observations were carried with 2K CCD as well as 4K CCD at the CBNUO. Our results show that variable stars can be detected using our algorithm even with observational data for which the field of view has changed. Our algorithm is useful to detect new variable stars and analyze them based on existing time-series data. The developed algorithm can play an important role as a recycling technique for used data

• Journal of environmental and Sanitary engineering
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• v.11 no.1
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• pp.9-15
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• 1996

The purpose of this study was to evaluate the decomposition efficiency of $NH_3$ odor gas using high frequency surface discharge body. The results from this study are as follows; 1, Voltage and frequency of electric elements have effects on removal of $NH_3$ odor. The higher these two elements were set up, the more efficiently deodorizing processing worked. In this experiment, the optimum voltage and frequency applicable were observed around AC 6.0 kVp-p and 24.0 kHz respectively. 2. The temperature, humidity and residence time were observed strong variables for NH$_3$ removal process. Its performance had limits at high temperature and humidity conditions. The longer the residence time continued, the more efficiently deodorization process worked. The experimental results showed that the deodorization was efficiently processed under such conditions as $30.0^{\circ}C$ in temperature, 60rh% in humidity and 0.3 sec in residence time. 3. It was observed that in deodorization experiment, $NH_3$ odor gas was perfectly decomposed under the concentration condition below 15.0ppm. Moreover it was considered as economic and practical in terms of maintenance cost when compared with other deodorization methods.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.725-740
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• 2008

In this study a multi-site daily precipitation generator which generates the precipitation with similar spatial correlation, and at the same time, with conserving statistical properties of the observed data is developed. The proposed generator is intended to be a tool for down-scaling the data obtained from GCMs or RCMs into local scales. The occurrences of precipitation are simultaneously modeled in multi-sites by 2-parameter first-order Markov chain using random variables of spatially correlated while temporally independent, and then, the amount of precipitation is simulated by 3-parameter mixed exponential probability density function that resolves the issue of maintaining intermittence of precipitation field. This approach is applied to the Nakdong river basin and the observed data are daily precipitation data of 19 locations. The results show that spatial correlations of precipitation series are relatively well simulated and statistical properties of observed precipitation series are simulated properly.

• Journal of the Korean Home Economics Association
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• v.39 no.3
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• pp.67-81
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• 2001

The purpose of this investigation was to examine whether early child-care experience, alone or in combination with mother/child factors, was associated with emotion regulation. Participants were forty 12-18 month-old infants, their mothers and their caregivers. Infants were observed in the Strange Situation to assess the pattern of emotion regulation. Mothers were interviewed, given Questionnaires, and observed in play. Caregivers were observed in child care to assess the caregiving environment. There were significant main effects of good quality child care on open emotion expression and heightening emotion expression. Significant interaction effects revealed that infants were more likely to be open emotion expression when high maternal sensitivity /responsiveness was combined with good quality child care, or nonmaterial care initiated prior to six month of age. Infants were more likely to be minimizing emotion expression when low maternal sensitivity/responsiveness was combined with nonmaternal care initiated after six month of age, or more than one care arrangement. Difficult temperament infants received nonrelative care were somewhat more likely to be minimizing emotion expression. Infants were more Likely to be heightening emotion expression when high maternal sensitivity/responsiveness was combined with relative care. Boys experiencing nonrelative care were more Likely to be heightening emotion expression.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1423-1426
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• 2007

The goal of this research is to develop and apply the integrational model for the pan evaporation and the alfalfa reference evapotranspiration in Republic of Korea. Since the observed data of the alfalfa reference evapotranspiration using lysimeter have not been measured for a long time in Republic of Korea, PM method is used to assume and estimate the observed alfalfa reference evapotranspiration. The integrational model consists of staochastics and neural networks processes respectively. The stochastics process is applied to extend for the short-term monthly pan evaporation and alfalfa reference evapotranspiration. The extended data of the monthly pan evaporation and alfalfa reference evapotranspiration is used to evaluate for the training performance. For the neural networks process, the generalized regression neural networks model(GRNNM) is applied to evaluate for the testing performance using the observed data respectively. From this research, we evaluate the impact of the limited climatical variables on the accuracy of the integrational operation of stochastics and neural networks processes. We should, furthermore, construct the credible data of the pan evaporation and the alfalfa reference evapotranspiration, and suggest the reference data for irrigation and drainage networks system in Republic of Korea.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.785-792
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• 2005

In order to reduce roadside and indoor air pollution for volatile organic compounds VOC), it may be necessary to apply photocatalyst-coated construction materials. This study evaluated the technical feasibility of the application of $TiO_2$ photocatalysis for the removal of VOC present in roadside or indoor air. The photocatalytic removal of five target VOC was investigated: benzene, toluene, ethyl benzene and o,m,p-xylenes. Variables tested for the current study included ultraviolet(UV) light intensity coating materials, relative humidity (RH), and input concentrations. Prior to performing the parameter tests, adsorption of VOC onto the current experiment was surveyed, and no adsorption was observed. Stronger UV intensity provided higher photocatalytic destruction(PCD) efficiency of the target compounds. For higher humidity, higher PCD efficiency was observed. The PCD efficiency depended on coating material. Contrary to certain previous findings, lower PCD efficiencies were observed for the experimental condition of higher input concentrations. The current findings suggested that the four parameters tested in the present study should be considered for the application of photocatalyst-coated construction materials in cleaning VOC of roadside or indoor air.

• Journal of Environmental Science International
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• v.8 no.6
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• pp.661-667
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• 1999

Estimating dimensions of attractors are the most basic tools to analyze properties of chaotical dynamic systems. In this paper, we estimate correlation dimensions of meteorological variables, such as wind speed (v) and temperature (T) observed in Kimhae International Airport when the land-sea breeze circulation is appeared and find low non-integer values that reflect the deterministic chaos characterizing the dynamics. We compare the results with the correlation dimensions of 2-dimensional model that is calculated by finite element method. Though the correlation dimensions of the calculated wind speed ( v) are less than those of the observed wind speed ( v), we can suggest that the land-sea breeze circulation has not a unique mechanism. The land-sea breeze phenomenon is a complicated dynamics, which is constructed with various scale motions of atmosphere. In further research, we hope to find more accurate dynamics of land-sea breeze through wide observations and using of more sophisticated prediction models.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.1
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• pp.1-8
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• 2022

Erythrocyte sedimentation rate (ESR) evaluation is a useful tool for monitoring disease activity in various inflammatory and non-inflammatory conditions. ESR is known to be influenced by a multitude of confounding factors. The present study aimed to assess the possible determinants of the ESR and its relationship with various risk factors involved in ischemic stroke. ESR and other hematological and biochemical parameters were investigated in 163 ischemic stroke patients (107 males and 56 females) selected based on imaging techniques including magnetic resonance imaging (MRI) or computed tomography (CT) scans. Statistical analysis was performed using the SPSS 16.0 software. Linear regression analysis showed a significant inverse relationship of hemoglobin (Hb) and hematocrit or packed cell volume (PCV) (P<0.001 for females; P<0.01 for males) with the ESR. It was observed that the red blood cell (RBC) count was not strongly correlated with the ESR (P<0.05 for both males and females). It was also observed that sex significantly affected the variables determining the ESR levels, whereas age had no effect. Gender differences were also observed with respect to Hb, RBC, PCV, mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and ESR. The possible determinants of higher ESR levels in ischemic stroke may be sex, Hb, hematocrit, and RBC count, but the role of other clinical and laboratory parameters cannot be underestimated.