• Journal of the Korea Society of Computer and Information
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• v.3 no.4
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• pp.139-144
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• 1998

Introduced into korea to diversify risk coming from the fluctuation of stock price with opening of the domestic capital market to foreigners, Suppress the turbulence of the dentistic securities market caused by the short term funds from foreign countries and vitalize investment in stock, the hedging transaction of stock index futures will promote the introduction of financial futures and commodity futures transaction. and it will contribute to enhancing the introduction all over the country and accelerating the advancement of the korea banking market. In addition, it is expected to make a great contribution to economic stability and smooth comic activity through its function of risk diversification and price decrement with the launch of the stock index futures.

• Ocean and Polar Research
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• v.40 no.4
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• pp.191-202
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• 2018

In this study we conducted a weekly monitoring exercise at a fixed station in the saltwater zone during the dry season (Jan-Mar, 2013) and wet season (Jun-Aug, 2013) to understand the fluctuations in phytoplankton communities and environmental factors in the Youngsan River estuary altered by a dike constructed in the coastal area. Phytoplankton communities displayed seasonality; diatoms were dominant during the dry season whereas dinoflagellates were dominant during the wet season. T-test analysis showed that water temperature was significantly different between the seasons whereas freshwater discharge from the dike was not significantly different. This suggests that seasonal variations of phytoplankton are more likely affected by water temperature than freshwater discharge. However, a short-term fluctuation was also observed in response to freshwater discharge; freshwater species appeared during or after the discharge in the dry and wet seasons and blooms of harmful species developed after the discharge. Phytoplankton communities may be affected by changes in physical factors such as turbidity and salinity and nutrient supply resulting from freshwater discharge. Especially, the nutrient supply may directly contribute to the harmful algal blooms (HABs) composed of dinoflagellates which can adapt to low salinity after freshwater discharge.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.914-925
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• 2011

The variation of streamflow is regarded as one of the most influential factors on the fluctuation of water quality in the stream. The characteristics of the variation should be taken into account in the plans for the management of Total Maximum Daily Loads (TMDLs). This study analysed and characterized spatial distribution and temporal variation of streamflow at each unit watershed in Guem-river basin. For the analysis of the distribution of streamflow, the type and the extent of the distribution were investigated for the unit watershed. For the analysis of the variation, short and long term changes of streamflow were examined. The result showed that most of the distributions were not log-normalized and the extent of variation tends to be greater at the unit watershed placed on the tributaries in the basin. A kind of margin could be granted to the unit watershed involving high variations so as to establish the water quality goal and load allotment more reasonably and effectively in view of whole waterbody.

• Journal of Plant Biotechnology
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• v.33 no.2
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• pp.123-131
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• 2006

Chinese cabbage (Brassica rapa ssp. pekinesis) is one of the most important vegetable crops in korea and other East Asian countries. Cytosolic fructose-1,6-bisphospha-tase (cytFBPase) is a key enzyme in sucrose biosyn-thesis, which controls the sucrose levels as well as the productivity at plants. The Chinese cabbage cytFBPase gene, BrFBPase, encodes the 340 amino acid polypep-tide, giving a theoretical molecular weight of 37.2 kD and a isolectric point of 5.4. BrFBPase showed high sequence identity with Brassica homologs and its functional domains, such as 12,6P$_2$ binding site or active site and F6P binding site, were highly conserved in diverse sources of organisms. Although the genome of Chinese cabbage seemed to be triplicated, BrFBPase appears to be a single copy gene. The expression of BrFBPase was examined at transcript and protein levels under various conditions. BrFBPase expression was observed only in photosynthetic source tissue, not in sink tissue. The expression was slightly higher during the day than at night, and it showed a diurnal cycle with circadian rhythmicity. Short-term exposure to low temperature inhibited the expression of the BrFBPase, while long-term exposure increased the expression, supporting that sugar levels are high in late autumn when temperature are low.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.215-223
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• 2012

This study was aimed to find factors responsible for export potential of oyster mushroom through postharvest treatments including high pressure $CO_2$ and anti-moisture pad. Temperature fluctuation during export simulation induced the condensation of excess moisture resulting in the quality loss due to browning and decay. Anti-moisture pad was effective on inhibition of browning occurrence in part. High temperature exposure ($15^{\circ}C$) as retail simulation greatly offset the positive effect of anti-moisture pad. Short term treatment of high pressure $CO_2$ delayed the surface color changes as hunter L, a, and b values. There was no consistent tendency in total sugar and phenolics between treatments. In general, the export potential of small size mush-room (export size) at harvest was higher than large ones (domestic size). The major factors asso-ciated with the quality decrease of oyster mushroom during export were moisture condensation in packages and temperature fluctuation. Further research is required to improve mushroom export procedures.

• Journal of Environmental Health Sciences
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• v.43 no.4
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• pp.267-272
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• 2017

Objectives: The purposes of the study were to analyze the temporal variation of carbon dioxide ($CO_2$) and particulate matter (PM) in daycare centers and evaluate the appropriateness of the official test method of one-time measurement. Methods: Indoor air quality in 46 daycare centers in the Seoul Metropolitan Area was measured as specified in the official test method of Indoor Air Quality Management law. In addition, indoor air quality in the 46 daycare centers was measured over 37 days using a real-time monitor (AirGuard K). Results: The daily means of $CO_2$ and PM in the 46 daycare centers were $1042.74{\pm}134.45ppm$ and $67.60{\pm}18.25{\mu}g/m^3$, respectively. Indoor air quality in the daycare centers showed significant temporal fluctuation. Measurements for single days were significantly different from the 37-day average exposure. Relative error of short term exposure decreased with an increase in the number of sampling days. The noncompliance rate for $CO_2$ using the official testing method was 2.17%, and none exceeded the $PM_{10}$ standard of $100{\mu}g/m^3$. With monitoring over 37 days, the daily noncompliance rate for $CO_2$ was 50.4% and the daily noncompliance rate for PM was 13.8%. Conclusions: When the official test method evaluates the indoor air at daycare centers one day per year, the results may not represent actual indoor air quality over a longer period of time. Real-time monitoring devices could be an alternative for managing indoor air quality.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.3
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• pp.100-116
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• 1993

It is experienced fact that unreasonable design criterion and unsitable operation management for the agricultural structures including reservoirs based on short terms data of monthly flows have been brought about not only loss of lives, but also enormous property damage. For the solution of this point at issue, this study was conducted to simulate long series of synthetic monthly flows by multi-season first order Markov model with selection of best fitting frequency distribution and to make a comparison of statistical parameters between observed and synthetic flows of six watersheds in Yeong San and Seom Jin river systems. The results obtained through this study can be summarized as follows. 1.Both Gamma and two parameter lognormal distribution were found to be suitable ones for monthly flows in all watersheds by Kolmogorov-Smirnov test while those distributions were judged to be unfitness in Nam Pyeong of Yeong San and Song Jeong and Ab Rog watersheds of Seom Jin river systems in the $\chi$$^2$ goodness of fit test. 2.Most of the arithmetic mean values for synthetic monthly flows simulated by Gamma distribution are much closer to the results of the observed data than those of two parameter lognomal distribution in the applied watersheds. 3.Fluctuation for the coefficient of variation derived by Gamma distribution was shown in general as better agreement with the results of the observed data than that of two parameter lognormal distribution in the applied watersheds both in Yeong San and Seom Jin river systems. Especially, coefficients of variation calculated by Gamma distribution are seemed to be much closer to those of the observed data during July and August. 4.It can be concluded that synthetic monthly flows simulated by Gamma distribution are seemed to be much closer to the observed data than those by two parameter lognormal distribution in the applied watersheds. 5.It is to be desired that multi-season first order Markov model based on Gamma distribution which is confirmed as a good fitting one in this study would be compared with Harmonic synthetic model as a continuation follows.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.791-799
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• 2005

The phased isolation intra-clarifier ditch system used in this study is a simplified novel process enhancing simultaneous removal of biological nitrogen and phosphorus in municipal wastewater in terms of elimination of additional pre-anaerobic reactor, external clarifier, recycle of sludge, and nitrified effluent recirculation by employing intrachannel clarifier. Laboratory-scale phased isolation ditch system was used to assess the treatability on municipal wastewater. When the system was operated at the HRTs of 6~12hours, SRTs of 9~31days, and cycle times of 2~8hours, the system showed removals of BOD, TN, and TP as high as 88~97%, 70~84%, and 65~90%, respectively. The rainfall in Korea is generally concentrated in summer because of site-specific characteristics. Especially, the wet season has set in on June to August. In combined sewers, seasonal variations are primarily a function of the amount of stormwater that enters the system. In order to investigate the effect of hydraulic shock loading on system performance, the laboratory-scale system was operated at an HRT of 6hours (two times of influent flowrate) during two cycles (8hours). The system performance slightly decreased by increasing of influent flowrate and decreasing of system HRT. Nitrification efficiency and TN removal were slightly decreased by increasing of influent flowrate (decreasing of system HRT), whereas, the denitrification was not affected by hydraulic shock loading. However, the higher system performance could be achieved again after four cycles. Thus, the phased isolation technology for enhanced biological nutrient removal in medium- and small-scale wastewater treatment plants suffering fluctuation of influent quality and flowrate.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.563-570
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• 2004

Phased isolation intrachannel clarifier ditch process developed in this study is an enhanced biological nutrient removal process employing two ditches with intrachannel clarifiers. Bench-scale phased isolation ditch process was used to evaluate the system performance on municipal wastewater and detailed assessment of internal behavior in a ditch and each reactions. When the system was operated at the HRTs of 6~12hours, SRTs of 9~31 days, and cycle times of 4hours, the system showed removals of BOD, TN, and TP as high as 88~97%, 73~78%, and 65~90%, respectively. The internal behavior were well matched on each reactions such as nitrification, denitrification, and phosphorus release and uptake. As the SRT became longer, TN removal increased gradually, whereas TP removal decreased contrarily. However, the system was capable of producing an effluent TP concentration 1mg/L or less even at longer SRTs except the case of solids discharge by malfunction of intra-clarifier occurred by its geometrical limit. The system performance slightly decreased by hydraulic shock loading(increasing of influent flowrate and decreasing of system HRT). However, the higher system performance could be achieved again after four cycles. Thus, the system reliability could be successfully achieved short-term hydraulic shock loading that occurred in medium- and small-sized wastewater treatment plants suffering fluctuation of influent quality and flowrate during wet season.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.173-174
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• 2009

For container shipping company, fuel oil prise is a considerable expense. In the last 3 years, fuel oil prises have risen considerably. An increasing fuel oil prise in container shipping, in the short term, is only partially compensated through surcharges and will therefore affect earnings negatively. This paper deals with the impact of increasing fuel oil price and capital costs for vessels on the number of vessels on the Asia-Europe trade. As per result of 'H' carrier's operation in 2008, there were no cost difference between 8 and 9 vessels operation in case the fuel oil price is USD 169/tons while adopt USD 31,818 as fixed cost. We can expect that the fuel oil price will not be decreased under USD 200 $/Ton on the basis of current high oil price phenomenon. When the fuel oil price is over USD 200 $/ton, therefore, 9 vessels operation is more economic than 8 vessel operation even if the fixed cost is over USD 35,000.