• Journal of Nutrition and Health
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• v.30 no.6
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• pp.715-726
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• 1997

This study was conducted longitudinally following the total nitrogen , total lipid, and lactose concentrations and their factors on concentrations of energy-yielding nutrients in human milk from 2-5 days to 12 weeks postpartum of 45 lactating Korean mothers. All samples were from well-defined subjects. And uniform collection procedures were used . Total nitrogen concentration of milk decreased significantly from 385mg/이 at 2-5 days to 201mg/dl at 12 weeks postpartum. Total lipid concentration increased from 1.98g/dl at 2-5 days to 3.09g/dl at 12 weeks postpartum. However, there was a large variation in the concentration of total lipids. Lactose concentration increased signifciantly from 6.53g/dl at 2-5 days to 7.48g/dl at 12 weeks. Total nitrogen concentration in milk was positively related to pregnancy weight gains at 2 and 6 weeks postpartum. Total lipid concentration was positively related to infant birth weight : however, it was negatively related to the maternal weight loss. In addition, total lipid concentration was positively related to parity and maternal percentage body fat at 12 weeks postpartum. Milk lactose concentration was positively related to parity at 2 weeks postpartum.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.2
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• pp.97-105
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• 1989

Recently, many studies on air quality prediction models have been performed to develope new ones. The purpose of the study is to obtain a method to predict $SO_2$ concentration simply in urban area using hour-to-hour meteorological data such as the wind speed, the incoming solar radiation, and the cloud coverages. The relationships between with speed and $SO_2$ concentrations are plotted in flgures. Predicted concentration curves are obtained for equation C=b/(1+au).

• Journal of Environmental Science International
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• v.17 no.6
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• pp.699-709
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• 2008

To understand the development mechanism of the aerosols in the surface boundary layer, the variation in the aerosol number concentration due to the divergence and convergence of the wind fields was investigated. The aerosol number concentration was measured in the size ranges of $0.3{\sim}10.0{\mu}m$ using a laser particle counter(LPC) from 0000 LST on 03 Feb. to 0600 LST on 07 Feb. 2004 at Mokpo in Korea during snowfall. The Velocity Azimuth Display(VAD) technique was used to retrieve the radar wind fields such as the horizontal wind field, divergence, and deformations including the vertical air velocity from a single Doppler radar. As a result, the distribution of the aerosol number concentration is apparently different for particles larger than $1{\mu}m$ during snowfall, and it has a tendency to increase at the beginning of the snowfall. The increase and decrease in the aerosol concentration due to the convergence and divergence of the wind fields corresponded to the particles with diameters greater than $1{\mu}m$. It is found that the fluctuations in the aerosol number concentration are well correlated with the development and dissipation of snowfall radar echoes due to the convergence and divergence of horizontal wind fields near the surface boundary layer in the inland during the snowfall.

• Journal of the korean society of oceanography
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• v.39 no.4
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• pp.234-242
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• 2004

The pigment composition and concentration of phytoplankton assemblages using HPLC in the adjacent waters of four nuclear power plants (Yonggwang, Kori, Wolsong and Ulchin) were investigated during the spring blooming in 2004. The mean concentration of chlorophyll a ranged from 563.8 to 2,949.0ng $l^{-1}$, with the lowest concentration at Kori and the highest concentration at Wolsong. Among the carotenoids, the amounts of fucoxanthin and chlorophyll $C_2$ were relatively higher than those of other pigments in the study site. As minor pigments, zeaxanthin, chlorophyll b, 19'-butanoyloxyfucoxanthin, diadinoxanthin, 19'-hexanoyloxyfucoxanthin, chlorophyll $C_3$ and peridinin were detected. The results of pigment composition and concentration showed that diatoms had an important proportion of phytoplankton community when a spring bloom occurred. Cyanobacteria was present relatively low density at the Wolsong and the green alga such as chlorophytes and prasinophytes were abundant at the Yonggwang and Kori, while dinoflagellates characterized by peridinin were common at Ulchin and Kori. The pigment composition and concentration of phytoplankton after passing through the cooling-water system of nuclear power plant were highly variable. No distinct trend of the change of each pigment composition and amount was detected but the variation of fucoxanthin and chlorophyll $C_2$ highly coupled with that of chlorophyll a. We pointed out that the diatom controlled the overall variation of phytoplankton biomass during the spring season.

• Journal of Environmental Science International
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• v.19 no.4
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• pp.447-457
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• 2010

This study aims to monitor the variation of concentration of PCDD/DFs between the gaseous phase-particulate phases in the ambient air of urban area in Korea. This monitoring is evaluated by using the Junge-Pankow model and the Koa absorption model with the application of the Octanol-air partition coefficient. In this study, the ambient air samples were analyzed according to each congener group of the PCDD/DFs by HRGC/HRMS, which have been investigated for the past 5 years. In the results, the annual variation in the concentration level of $\Sigma$PCDD/DFs in TSP was increased from $1588\;fg/m^3$ in 1998 to $5123\;fg/m^3$ in 2002, and from 31 fg I-TEQ/$m^3$ to 94 fg I-TEQ/$m^3$ in the $\Sigma$I-TEQ. In the case of PUF of gaseous phase sample, their variation was increased from $1615\;fg/m^3$ in 1998 to $2237\;fg/m^3$ in 2002, and in the $\Sigma$I-TEQ from 12 fg I-TEQ/$m^3$ to 17 fg I-TEQ/$m^3$. The relative coefficient between the gas phase concentration of PCDD/DFs and the temperature was a value of 0.744; the contributive rate of the temperature to the gaseous phase concentration was 0.554. According to the results, the pattern of the coefficient of distribution based on log $p_L^0$ is similar to the ambient air of the urban areas.

• Journal of Environmental Science International
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• v.14 no.11
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• pp.1035-1047
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• 2005

By using hourly $NO_2$ concentration data$(1998\~2000)$ at the Busan Metropolitan City air qualify monitoring sites, characteristics of daily mean value of $NO_2$ concentration was discussed in space and time. The correlation between $NO_2$ concentration and other relating air pollutants was analyzed by using SAS program and meteorological parameters as well. After choosing representative 4 areas, this study used hourly concentration data$(1998\~2000)$ from air quality monitoring sites on $NO_2,\;NO,\;O_3,\;CO,\;SO_2\;and\;PM_{10}$. Typical metropolitan characteristics of two peaks in a day was shown in the variation of $NO_2$ concentration of Busan city.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.259-267
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• 1995

This study was conducted to evaluate the effects of pressure and dissolved oxygen concentration on the activated slut비e and to determine the optimum depth of deep shaft process. Some results from this study were summarized as follows. 1. It is considered that low sludge product in the activated sludge system maintaining high dissolved oxygen concentration is attributed to the increase of endogeneous respiration rate caused by the increase of aerobic zone in the sludge floe. 2. The increase of dissolved oxygen concentration does not affect to the increase of organic removal efficiency greatly and therefore the limiting factor is the substrate transfer into the inner part of floe. 3. The yield coefficient, Y is decreased in proportion to the increase of oxygen concentration. In this study, Y values arre ranged from 0.70 to 0.41 according to the variation of dissolved oxygen concentration from 18.0mg/$\ell$ to 258 mg/$\ell$. 4. The optimum depth of deep shaft process should be determined within the limits of non-toxicity to the microorganism and it is about loom in this study.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1972-1979
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• 2003

Transport of a scalar quantity, such as chemical concentration or temperature, is important in many engineering applications and environmental flows. Here we report on results obtained from the large eddy simulations of flow and concentration fields inside the tank performed using a spectral multi-domain technique. The computations were driven by specifying the impeller-induced flow at the blade tip radius (Yoon et al. $^{(1)}$). This study focused on the concentration development at different molecular diffusivities in a stirred tank operated under turbulent conditions. The main objective of the work presented here is to study the large-scale mixing structure at different molecular diffusivities in a stirred tank by using the large eddy simulation. The time sequence of concentration and flow fields shows the flow dependency of the concentration development. The presence of spatial inhomogenieties is detailed by observing the time variation of local concentration at different positions.

• Journal of the Korean Solar Energy Society
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• v.26 no.1
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• pp.65-71
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• 2006

This study describes to analyze variation of carbon dioxide gas concentration by experimental and theoretical method according to the using patterns of ventilation system in a model classroom. Concentration of $CO_2$ gas varied by the occupancy and the ventilation systems are operating or not. More than 850 CMH ventilation system can maintain $CO_2$ gas concentration lower than 1,000 ppm along the class time and can be adopted the government guideline. Theoretical modeling of the concentration was performed at well-mixed ideal condition. Delays of concentration decay were shown at each case compared to actual.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.6
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• pp.545-554
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• 1998

The diurnal variation of O3 concentration shows two peaks, the first peak at noontime and the secondary peak at night. In order to show why the secondary peak, high nocturnal O3 concentration, occurs without sunlight which is a essential factor of a photochemical response, the O3 concentration, several weather elements and synoptic weather map were used for June∼September at 1995, 1996. The mean concentration of high nocturnal O3 concentration days is higher by 5.4 ppb than that of low nocturnal O3 concentration days. The nocturnal O3 concentration is higher than that of diurnal O3 concentration during high nocturnal O3 concentration days, at July, 1995 and June, 1996. The high nocturnal O3 concentration is related to low air pressure, high cloud cover and high wind speed. The correlation coefficient, r. between nocturnal O3 concentration and wind speed, pressure and cloud cover is 0.387, -0.218, and 0.194, respeftiviely. It is interesting that the O3 concentration increases at Pusan when the typhoon passes by. The same result showed at Taegu when the typhoon FAYE passed by. According to the analysis of nocturnal O3 concentration for June∼September at 1995 and 1996, it seems that the high nocturnal O3 concentration relates to the trough and cyclones passing by Pusan.