• Journal of Korean Society of Forest Science
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• v.107 no.1
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• pp.43-49
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• 2018

This study was conducted to investigate the effects of warming and precipitation manipulation on seasonal changes in fine root production (FRP) and fine root mortality (FRM) of 33-month-old Pinus densiflora seedlings for two years. The seedlings in warmed plots were warmed with $3.0^{\circ}C$ higher using infrared heaters. The air temperature of warmed (TW) plots was set to increase by $3^{\circ}C$ compared to temperature control (TC) plots, and the three precipitation manipulation consisted of precipitation decrease (-30%; PD), precipitation increase (+30%; PI) and precipitation control (0%; PC). FRP ($mm\;mm^{-2}\;day^{-1}$) was significantly altered by only precipitation manipulation (PC: 3.57, PD: 4.59, PI: 3.02), while warming had no significant effect on the FRP and FRM. Meanwhile, interactions between warming and precipitation manipulation and seasonal changes had no significant effects on FRP and FRM. However, the influences of seasonal changes in soil temperature and soil moisture on FRP and FRM were different according to warming. In TW plots, FRP showed a positive relationship with soil temperature, and FRM showed a negative relationship with soil moisture. On the other hand, in the TC plots, FRP showed a positive relationship with soil moisture, and there were no relationships between FRM and soil temperature and moisture. These results indicate that the climate factors that affect FRP and FRM might vary as the warming progresses.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.373-386
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• 2017

The study was conducted to investigate seasonal nutrient dynamics in rice-cultivated soils collected from farmhouses of three large-scale environment-friendly agricultural districts (LEAD), Jangheung, Suncheon, and Okcheon in which environmental-friendly agriculture has been exemplarily practiced in Korea. Among three districts, Crop- livestock cycling organic farming system had been introduced only in Jangheung. pH and EC of farmhouse soils of three LEADs were ranged between 5.5 - 6.7 and $0.4-1.0dS\;m^{-1}$ from March to September, respectively. T-N was observed to be high on the farmhouse soil in Suncheon and K was observed to be lowest on farmhouse soil in Okcheon. Concentration of $NH_4-N$ in soil was observed to be highest on June, in particular on the farmhouse in Jangheung, but rapidly decreased due to the loss of fertilizer applied in Spring. Yield and harvest index were the highest on the farmhouse in Okcheon in which total annual gross production $ha^{-1}$ was nearly three time higher than those of other two farmhouses. Farmhouse soil of Okcheon was maintained the highest seasonal nutrient balance due to the high input of fertilizer. It was estimated that K balance in the farmhouse soil in Suncheon dropped to $-60kg\;ha^{-1}$ on September, and it might have some effect on the less rice productivity due to K deficiency. Farmhouse soil in Jangheung was maintained low seasonal balance of T-N and P but showed the highest N use efficiency in the rice grain. Based on above-mentioned results, we think Jangheung farmhouse can be recommended as a model farmhouse of LEADs.

• Atmosphere
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• v.26 no.4
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• pp.599-615
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• 2016

This study investigates the accuracy of short-term ocean predictions during the development of ocean stratification for the Korea Meteorological Administration (KMA) Global Seasonal Forecast System version 5 (GloSea5) as well as the effect of atmosphere-ocean coupling on the predictions through a series of sensitive numerical experiments. Model performance is evaluated using the marine meteorological buoys at seas around the Korean peninsular (KP), Tropical Atmosphere Ocean project (TAO) buoys over the tropical Pacific ocean, and ARGO floats data over the western North Pacific for boreal winter (February) and spring (May). Sensitive experiments are conducted using an ocean-atmosphere coupled model (i.e., GloSea5) and an uncoupled ocean model (Nucleus for European Modelling of the Ocean, NEMO) and their results are compared. The verification results revealed an overall good performance for the SST predictions over the tropical Pacific ocean and near the Korean marginal seas, in which the Root Mean Square Errors (RMSE) were $0.31{\sim}0.45^{\circ}C$ and $0.74{\sim}1.11^{\circ}C$ respectively, except oceanic front regions with large spatial and temporal SST variations (the maximum error reached up to $3^{\circ}C$). The sensitive numerical experiments showed that GloSea5 outperformed NEMO over the tropical Pacific in terms of bias and RMSE analysis, while NEMO outperformed GloSea5 near the KP regions. These results suggest that the atmosphere-ocean coupling substantially influences the short-term ocean forecast over the tropical Pacific, while other factors such as atmospheric forcing and the accuracy of simulated local current are more important than the coupling effect for the KP regions being far from tropics during the development of ocean stratification.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1225-1230
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• 2008

A new approach based on the Seasonal Mann-Kendall Trend Analysis, was presented in this paper, in order to estimate effect of water quality management policy in Kyoungan Stream which is one of major tributaries into the Lake Paldang. The estimation was undertaken by comparing water quality trend slopes before and after implementation of the policy. The monthly water quality data of Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Nitrogen (TN) and Total Phosphorus (TP) measured from 1992 to 2005, were analyzed to determine the Kendall slopes before and after the Han River special policy implemented at 1998. The results indicated that the 1998 special policy would be effective in water quality improvement not at upstream but at downstream. This result agrees well with the previous water quality studies at Kyoungan stream. It was suggested that the presented approach could be an useful tool to estimate effect of a water quality management policy.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.329-338
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• 2003

The purpose of this study is to identify the temporal and spatial variation of stable isotopic compositions of surface waters and shallow ground waters at a local watershed(100$Km^2$) near the Muju area. For oxygen and hydrogen isotope analysis, water samples were collected from 19-22 sites during August, October 2001, through April 2002. Seasonal variation in the isotopic compositions of surface waters was clearly shown. However, the degree of such isotopic variation was highly attenuated in shallow ground waters because of mixing with preexisting ground waters. Isotope values of surface waters and ground waters were very similar in each season, indicating that precipitation/ground water/surface water interactions were very active and continuous in the watershed. Stable isotopic ratios of surface waters in the study area were lighter than those of the downstream reach of Geum River on south, indicating “latitude effect”. Both “altitude effect” and “amount effect” were also shown in the stable isotopic ratios of surface waters in the study area as well as seasonal variation of stable isotopes.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.615-628
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• 2004

In order to elucidate seasonal sedimentary characteristics and depositional environment after construction of seawall on macrotidal flat, a seasonal observations of surface sediments (total 450) and sedimentation rates on 4 transects have been investigated for 2 years. The eastern area of Iwon tidal flat, has been changed from semi-closed coast to open coast by construction of seawall, shows general seasonal changes similar to characteristics of open coast type, which represented both fining and bad sorted distribution due to deposition of fine sediments under low energy condition in the summer, and relatively coarser and better sorted distribution because of erosion of fine sediments in the winter. In considering angles of transects, distribution patterns of surface sediments, the northern and southern parts of eastern tidal flat are dominantly influenced by wave and tidal effects, respectively. As time goes by, the eastern tidal flat shows coarsening-trend of surface sediments caused by direct effect of tidal current, were and typhoon. Meanwhile the western area of seawall, which has been re-formed by construction seawall, is sheltered from northwesterly seasonal wind. The seasonal change pattern of western area of seawall is slightly different from that of eastern tidal flat. Mean grain size and sorting of surface sediments during spring is finer and worse than those during summer. This seasonal change pattern maybe influenced by topographic effects caused from the construction of seawall. In consideration of all result, the transport of fine sediments in the study area, which is supplied to limited sediments, shows clockwise circulation pattern that fine sediments are transported from the eastern tidal flat to the western area of seawall because of blocking of seawall in the winter and are transported reversed direction the summer. As a result, many changes have been observed in the study area after construction of seawall; however, this change is still in progress and is expected to need continuous monitoring.

• Food Science and Preservation
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• v.22 no.3
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• pp.303-313
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• 2015

This study investigates the physicochemical, microbiological and sensory characteristics of seasonal salted-Kimchi cabbages to provide basic data on its uniform quality. Generally, seasonal salted-Kimchi samples had different pH values at initial storage periods, but there was no difference in pH between the seasonal samples when stored for longer periods. The samples from the fall and winter seasons were relatively low in acid and high in solid soluble content compared to samples from other seasons. Salted-Kimchi cabbages in the summer showed the highest microbiological number compared to samples from other seasons. In the sensory evaluation, there were differences in the appearance, aroma, and taste, depending on seasonal samples at different storage periods. The correlation coefficient between the quality characteristics in the seasonal samples showed a positive or negative correlation between the quality characteristics at 1% significant level. In the principal component analysis, F1 and F2 were shown the 51.81% and 14.23% of the total variance (66.21%), respectively. In the PCA pattern of seasonal salted-Kimchi cabbages during storage periods, winter samples were distributed on the top of F2, spring samples were in the middle of F2, while the rest of the samples were distributed on the bottom of F2. According to increasing storage periods, initial storage samples were distributed at the left of F1, while other samples were located at the right of F2.

• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.303-309
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• 2011

This study was carried out to investigate the evaluation of insecticidal efficacy and control effect in field of 10 environmental-friendly agricultural materials (EFAM) and seasonal occurrence at the vineyards to the Lycorma delicatula. L. delicatula nymphs occurred from late May to late August the highest early June (1st nymph) while adults occurred from late July to November with the highest peak of early October (preovipositing female) in 2010. Total population density of L. delicatula was the highest in early June. For the 3rd~4th nymphal instars and adults, EFAM (Spider, Jindikap-plus and Byejin-${\alpha}$) showed perfect insecticidal activity 2hour after treatment. Seoncho showed insecticidal activities 96.7% within 48 hour. Residual effects between EFAM showed 55.5% Spider at recommended concentration at 7 days after treatment(DAT), the other EFAM had low efficacy. Jindikap-plus and Spider showed 99% control value on nymphs in the field test at 3DAT, appeared control value more than 90% at 7DAT. Also, the control effects of Jindikap-plus and Spider were showed the adult mortality of 100% and 98.2% respectively at 3DAT, 90.6% and 84.6% respectively at 7DAT. Whereas the other EFAM had low efficacy. Jindikap-plus and Spider were excellent control effects compared with Acetamiprid WP.

• Journal of Environmental Science International
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• v.10 no.6
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• pp.423-429
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• 2001

Satellite data, with sea surface temperature(557) by NOAA and sea level(SL) by Topex/poseidon, are used to estimate characteristics on the variations and correlations of 557 and SL in the East Asian Seas from January 1993 through May 1998. We found that there are two climatic characteristics in the East Asian seas the oceanic climate, the eastern sea of Japan, and the continental climate, the eastern sea of China, respectively. In the oceanic climate, the variations of SL have the high values in the main current of Kuroshio and the variations of 557 have not the remarkable seasonal variations because of the continuos compensation of warm current by Kuroshio. In the continental climate, SL has high variations in the estuaries(the Yellow River, the Yangtze River) with the mixing the fresh water and the saline water in the coasts of continent and 557 has highly the seasonal variations due to the climatic effect of continents. In the steric variations of summer, the eastern sea of Japan, the East China Sea and the western sod of Korea is increased the sea level about 10~20cm. But the Bohai bay in China have relatively the high values about 20~30cm due to the continental climate. generally the trends of SST and SL increased during all periods. That is say, the slopes of 557 and SL Is presented 0.29$^{\circ}C$/year and 0.84cm/year, respectively. The annual and semi-annual amplitudes have a remarkable variations in the western sea of Korea and the eastern sea of Japan. In the case of the annual peaks, there appeared mainly In the western sea of Korea and the eastern sea of .Japan because of the remarkable variations of SL associated with Kuroshio. But in the case of the semi-annual peaks, there appeared in the eastern sea of Japan by the influence of current, and in the western sea of Korea by the influence of seasonal temperature, respectively. From our results, it should be believed that 557 and SL gradually Increase in the East Asian seas concerning to the global warming. So that, it should be requested In the international co-operation against In the change of the abnormal climate.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.295-299
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• 1995

This study was conducted to find the control methods, status of overwintering and seasonal occurrence of Erioccoccus largerstroemiae on persimmon trees in Ch'ondo area, Kyongbuk province in Korea. Usually, overwintering eggs were sheltered in bark, among them the rate of alive eggs was 28.7%. The activiation of garpe-myrtle scale showed from late April, and they have three generations per year. The first occurrence of larval stage of Erioccoccus largerstroemiae starts from late June to early July, the second occurrence begins from middle August to late August, and from late June to early July, the second occurrence begins from middle August to late August, and from middle September to late September is the third, thus, three peaks of occurrence revealed in early July middle August, and late September respectively. Average number of eggs conceived in female adult was 229.3. Spray effect of chemical control showed as follows; lime sulfur with tow applications of pesticides (late June, late August) at 97.8%, machine oil with tow applications of pesticides (late June, late August) at 96.8%. And during the growing period, the spray results using three applications of pesticide only (late June, late August, amid September) showed 77.2% in field condition.