• Journal of Korean Society for Atmospheric Environment
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• v.23 no.4
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• pp.487-497
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• 2007

Increase of the greenhouse gases emissions during last century has led remarkable changes in our environment and climate system. Continuous monitoring of atmospheric constituents over the world is positively necessary to understand these changes around us. The concentrations of greenhouse gases ($CO_2,\;CH_4,\;N_2O,\;CFCs$) have been continuously measured at Global Climate Change Monitoring station in Gosan, Jeju since January, 2002. In this study, the variation characteristics of greenhouse gases as well as their annual, seasonal and diurnal trend using the data from January, 2002 to December, 2005 were analyzed. The raw data which was used in the analysis were validated with the methods recommended by WDCGG (World Data Center for Greenhouse Gases). The concentration of $CO_2$ was increasing continuously by 2.1 ppm/year, while $CH_4$ did not show any increasing or decreasing trend clearly for 4 years. The concentration of $N_2O$ was slightly increasing and CFCs were decreasing except CFC-12 which has longer lifetime compared with other CFCs. The variations of the greenhouse gases at Gosan were shown to be consistent with the global trend. But the concentration level of $CO_2$ in Korea was more or less higher than abroad.

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.134-143
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• 2011

The present study aimed to investigate the diurnal variations in air concentrations and exchange fluxes of ammoniacal nitrogen ($NH_x$: ammonia ($NH_3$) and particulate ammonium) in a subalpine deciduous forest in central Japan during a week in summer. The $NH_3$ concentrations ($0.50\;{\mu}g\;N\;m^{-3}$ on average) showed a clear circadian variation, i.e., high and low in the daytime and nighttime, respectively. The concentration of particulate ammonium in the coarse fractions was extremely low, whereas that for the PM2.5 fraction was relatively high $0.55\;{\mu}g\;N\;m^{-3}$ on average). The main inorganic ion components of PM2.5 at the study site were ammonium and sulfate. The exchange fluxes of $NH_x$ were bidirectional. Both the maximum and minimum values occurred in the daytime, i.e., $0.39\;mg\;N\;m^{-2}\;hr^{-1}$ of downward flux and $0.11\;mg\;N\;m^{-2}\;hr^{-1}$ of upward flux for $NH_3$ and $0.25\;mg\;N\;m^{-2}\;hr^{-1}$ of downward flux and $0.13\;mg\;N\;m^{-2}\;hr^{-1}$ of upward flux for PM2.5 ammonium. The exchange fluxes of $NH_x$ at night could be considered as zero. The mean deposition velocity during the research period was almost zero for both $NH_3$ and PM2.5 ammonium. The atmosphere-forest exchange of $NH_x$ in the forest during the study period was balanced. The remarkably large deposition of $NH_x$ was attributable to meteorological events such as showers the night before that thoroughly washed the forest canopy and subsequent clear skies in the morning, which enhanced convection. The cleaning effect of rainfall and the rapid change in convection in the early morning should be monitored to evaluate and generalize the gas and particle exchange in a forest.

• Ocean and Polar Research
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• v.25 no.1
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• pp.89-106
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• 2003

Analyses of tidal observations and a numerical model of the $M_2$ and $M_4$ tides in the Uldolmok waterway located at the southwestern tip of the Korean Peninsula are described. This waterway is well known fer its strong tidal flows of up to more than 10 knots at the narrowest part of the channel. Harmonic analysis of the observed water level at five tidal stations reveals dramatic changes in the amplitude and phase of the shallow water constituents at the station near the narrowest part, while survey results show a decreasing trend in local mean sea levels toward the narrow section. It was also observed that the amplitudes of semi-diurnal constituents, $M_2$ and $S_2$ are diminishing toward the narrowest part of the waterway. Two-dimensional numerical modeling shows that the $M_2$ energy flux is dominated by the component coming from the eastern boundary. The $M_2$ energy is inward from both open boundaries and is transported toward the narrow region of the channel, where it is frictionally dissipated or transferred to other constituents due to a strong non-linear advection effect. It is also shown that the $M_4$ generation is strong around the narrow region, and the abrupt decrease in the M4 amplitude in the region is due to a cancellation of the locally generated M4 with the component propagated from open boundaries. The superposition of both propagated and generated M4 contributions also explains the discontinuity of the M4 phase lag in the region. The tide-induced residual sea level change and the regeneration effect of the $M_2$ tide through interaction with $M_4$ are also examined.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.181-194
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• 2015

Spatial-temporal meteorological features of the Ulsan metropolitan region (UMR) were analyzed using observations and high-resolution numerical modeling. Long-term trend analysis (1970~2013) showed a significant increase of $0.033^{\circ}Cyr^{-1}$ in the 5-year moving average temperature, although detailed short-term features varied, whereas wind speed and relative humidity over the same period displayed clear decreases of $-0.007ms^{-1}$ and $-0.29%yr^{-1}$, respectively. These trends indicate the effects of regional climate change and urbanization in the UMR. Seasonal variations averaged for the most recent three years, 2011~2013, showed that temperatures in three different regions (urban/industrial, suburban, coastal areas) of the UMR had similar seasonality, but significant differences among them were observed for a certain season. Urban and industrial complex regions were characterized by relatively higher temperatures with large differences (max.: $3.6^{\circ}C$) from that in the coastal area in summer. For wind speed, strong values in the range from 3.3 to $3.9ms^{-1}$ occurred in the coastal areas, with large differences clearly shown between the three regions in September and October. Diurnal variations of temperature were characterized by pronounced differences during the daytime (in summer) or nighttime (in winter) between the three regions. Results from the WRF modeling performed for four months of 2012 showed large variations in gridaverage temperature and winds in the UMR, which displayed significant changes by season. Especially, a clear temperature rise in the urban center was identified in July ($0.6^{\circ}C$ higher than nearby urban areas), and overall, relatively weak winds were simulated over urban and inland suburban regions in all seasons.

• Journal of Environmental Science International
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• v.10 no.3
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• pp.179-185
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• 2001

To investigate daily variations of water mass distribution in the west and the east parts of Jeju Island, we implemented observations from June 20 to 22, 1997. (The results are as follows : Temperatures in the east and the west were similar in the surface, but $15.02^{\circ}C$ and $13.8^{\circ}C$ in the bottom, respectively.) In the east and west, the surface and the deep salinities are 33.81, 33.34 and 34.33, 34.11 respectively. The east shows higher temperature and salinity than the west. The distributions of nitrate in the east and the west were very similar in the surface regions.(In the deep regions, however, the east shows higher than the west.) The east shows higher phosphates than the west both in surface and deep regions. The silicate had similar distributions to nitrate. Chlorophyll-a of the west was twice higher than that of the east. The daily variations of temperature and salinity were largest at 30m depth, and pH was not much changed in the depth and the pH in day was higher than that at night. The variations of nutrients were much changed in the depth, and nitrate and phosphate at night were higher than those in day. Daily variations of silicate, however, was not much changed in the observation times. Ratio of N/P in the east and the west were 13 and 16, respectively, so that the west was higher than the east. However the ratios were two times higher both in the east and the west in day, when planktons are more active than at night. Si/P ratio showed little different between day and night and between surface and deep regions. The correlation of nitrogen and phosphorus was high (plus relation), and the correlation of AOU, nitrogen and phosphorus was high(plus relation) in the east, however, not high in the west.

• Atmosphere
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• v.25 no.4
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• pp.707-718
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• 2015

This study investigates the characteristics of turbulent fluxes observed at Ieodo Ocean Research Station (IORS) in autumn 2014. The 10 Hz IORS data is quality controlled and calculated to be the 30 minutes turbulent fluxes. The quality control consists of five steps: a weather check, Vickers and Mahrt (VM) sequential check, VM parallel check, flag check, and direction check. Since the IORS is an open-sea station with no orographic influence, there are no significant diurnal variations for the turbulent fluxes and 10 m wind speed. According to stabilities, the unstable and semi-unstable states appear more than 28% and 70% in autumn, respectively and they have strong winds of over $10m\;s^{-1}$. In addition, the turbulent fluxes increase with increasing wind speed. In particular, the latent heat flux and its deviations are clearly shown because the latent heat flux is influenced by the change of both the sea surface roughness and wave height induced by the wind. To demonstrate the changes of the turbulent fluxes before and after typhoon, Vongpong (1419), which is the most intense typhoon affecting the Korean Peninsula in 2014, is considered. The turbulent flux fluctuates in accordance with the location of Vongpong. The turbulent fluxes have a large (small) variation when Vongpong approaches (retreats) at the IORS. The overall results represent that the IORS data helps us understand physical processes related to air-sea interaction by providing the valuable and reliable observed data.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2000.11a
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• pp.81-84
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• 2000

Effects of different photoperiod regimens on the cellular and humoral immunity in broiler chickens were studied(Exp 1). Total one hundred ninety two one-day-old commercial broiler chicks(Cobb$\times$Cobb) were raised between constant lighting(CL) and intermittent lighting (1h light: 3h darkness(IL; 1l; 3D) Body weight, feed intake and feed conversion were measured for seven week. Peripheral blood and splenic lymphocyte activities were tested at 3 and 5 wk of age by performing a mitogen cellproliferation assay with a polyclonal T-cell mitogen, concanavalin A (Con A), and B-cell mitogen, lipopolysaccharide (LPS). To investigate the effect of photoperiod on the humoral immunity, chicks were immunized with sheep red blood cell(SRBC) and iinactivated Newcastle disease virus(NDV) vaccine. Total immunoglobulin G(IgG) concentration was also determined. Diurnal change of melatonin was tested in sera. In experiment 2, 0.1ml melatonin were subcutaneously injected from three to five weeks old if immunomodulation effect of lighting regimen was due to the melatonin or not. Injections of melatonin were made at 0700h and the dosage was 10ng (M2), 100ng(M3), 1$\mu\textrm{g}$(M4) per bird daily, respectively. control were quivalent injections of vehicle(M1). Lymphocyte activities were tested and humoral immunities were examined at 5 weeks of age. Blood melatonin concentration was determined at 0h, 1, h, 2h, and 3h posterior to injection at five weeks old. It was higher in CL chicks than IL chickens during the subsequent period of 3 to 5 wk of age. However, weight gain of chicks raised IL were significantly higher at 6 wk of age than CL(P<0.05). Antibody response to NDV was not affected by both photoperiod regimens and melatonin injection, whereas anti-SRMB titer and IgG concentration were enhanced. Lymphocyte activity of chickens raised under IL was sighificantly higher than those of chickens raised under CL. Melatonin injection also increased lymphocyte activity. When peripheral blood lymphocytes were used, proliferation response to LPS and Con A were significantly increased in M2 and respectively. The results of this experiments suggest that IL improved host immune response and melatonin have immunomodulatory roles.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.47-54
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• 2009

This study was conducted to consider the characteristics of PM10(particulate matter with aerodynamic diameters less than 10 ${\mu}m$) concentration according to land-use in Busan coastal area. Fine particle is affected by emissions, geographical conditions and meteorological factors. In case industrial area, Gamjeondong(inland) PM10 concentration was higher than Noksandong(seashore) at all season except for Summer. Primary peak at Gamjeondong cleared than Noksandong in Fall and Winter. In case green area, Daejeodong(inland) PM10 concentration was higher than Dongsamdong(seashore) at all seasons. In case commercial area, primary peak occurrence time at Jeonpodong lagged one hour according to season and diurnal change of PM10 concentration at Gwangbokdong was higher than Jeonpodong in Spring. In case residential area, high PM10 concentration(80~90 ${\mu}g/m^3$) lasted for six hours during the daytime in Spring at Deogcheondong and Yongsuri(inland).

• The Korean Journal of Quaternary Research
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• v.14 no.2
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• pp.101-107
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• 2000

Using the phytogram system, this study monitored hourly environmental factors(climate and soil), and radial growths and cambium activities of conifers in Worak mountain for 28 months from May 1996 to October 1998 to examine the influences of climatic factors on tree growths/carnbium activities of conifers in Worak Mountain, Korea. The phytogram system first puts a fine electrode into cambial zone. This device can automatically record environmental factors and cambium electrochemistry(hydration and proton levels). Dendrometers are attached to the phytogram for monitoring seasonal dynamics of cambial growth. We compared the results of radial growth by species and by diameter class. The growth decreased in order of Larix leptolepis, Pinus densiflora and Pinus rigida. Pre-monsoon growths were fast and May-June moisture regime was the most critical for all species. In the middle of September, radial growths were finished. The proton level and stem diameter reached the minimum at 4 p.m. On the other hand, the hydration level reached the maximum at 4 p.m. This diurnal change resulted from transpiration and the release of water from phloem storage to sapwood through xylem stream.

• Korean Journal of Environmental Agriculture
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• v.21 no.1
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• pp.69-73
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• 2002

Lettuce (Lactuca sativa L.) plants were grown under hydroponic system to characterize the diurnal change of nitrate concentration and nitrate uptake rate and to examine the effect of short term cold treatment to rhizosphere on nitrate concentration and uptake rate in lettuce plant. The nitrate concentrations in midrib were two times higher than those in leaf. Nitrate concentration in the shoot reached to minimum (8.7 mg-N/GDW) at 14:00 and, thereafter, increased continuously until 23:00. During 11:00$\sim$17:00, nitrate uptake by lettuce plant was maximum (4.8 mg-N/GDW-Root/hr). Short term cold treatment reduced nitrate concentration in the shoot by 14$\sim$18%, and nitrate uptake rate by 50$\sim$55%, respectively. These results showed that short term cold treatment before harvest could be applied for the purpose of reduction of nitrate concentration in the leaf under hydroponic culture.