• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.5
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• pp.37-49
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• 2023

The drought risk has been increasing recently due to climate change causing the extreme climate to be more frequent. In order to supply agricultural water stably under drought, it is necessary to operate an agricultural reservoir in response to drought. To this end, it is crucial to establish appropriate drought response operation rules considering weather conditions and reservoir status. In the reservoir operation simulation, the supply amount differs from the actual reservoir supply for many reasons, including maintaining water levels for supply and accommodating farmers' requests. So, for a more realistic reservoir operation simulation, it is necessary to reflect the reservoir operation rules of the actual water management site. Therefore, in this study, through a survey, the standards for limitation of agricultural water supply applied to agricultural reservoirs in Korea were investigated, and the criteria for drought response reservoir operation (DRO) were established based on the survey. Then, the DRO was applied to the irrigation period for nine subject reservoirs. The applicability was evaluated by comparing the DRO result to the operation result of HOMWRS (Hydrological Operation Model for Water Resources System). The reservoir drought index, storage rate, and daily supply were compared for evaluation. From the result, DRO showed more stable operation results in most cases against drought as it has fewer days of water supply limitation and a somewhat reservoir storage rate which can be utilized for prolonged drought.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.2
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• pp.419-432
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• 2013

This study investigates the actual status of Saturday program operation in Busan and explores the routes for acquiring information about the Saturday program and satisfaction with the program operation with the subjects of middle school students residing in Busan in order to develop efficient operation methods and also find ways to enhance the participation rate of the students. Therefore, with the subjects of 569 first, second, and third graders at 3 middle schools located in Busan, this research investigated the actual status of Saturday program operation in Busan to figure out the participation rate and satisfaction of the Saturday program, efficient operation methods for the Saturday program and ways to encourage participation in the Saturday program. It is needed to install cooperative Saturday program support centers to be operated collaboratively by local autonomous entities and the offices of education afterwards. And it is necessary to figure out which institution should take charge of the Saturday program according to the requests from teachers and students so that the proper institution can secure the budget and manpower and build a system to develop and operate the Saturday program.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.157-165
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• 2011

This study investigated speech rate and intonation slope (least square method; F0, quarter-tone) in normal and CI children's utterances. Each group consisted of 12 people and were divided into groups of children with CI operation (before 3;00), children with CI operation (after 3;00), and normal children. Materials are composed of four kinds of grammatical dialogue sentences which are lacking in respect. Given three groups as independent variables and both speech rate and intonation slope as dependent variables, a one-way ANOVA showed that normal children had faster speech rates and steeper intonation slopes than those of the CI group. More specifically, there was a statistically significant speech rate difference between normal and CI children in all of the sentential patterns but imperative form (p<.01). Additionally, F0 and qtone slope observed in sentential final word showed a significant statistical difference between normal and CI children in imperative form (f0: p<.01; q-tone: p<.05).

• International Journal of Highway Engineering
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• v.17 no.3
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• pp.125-132
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• 2015

PURPOSES : The present study aims to evaluate the added $CO_2$ emissions incurred from accelerating operation when to increase the speed up to the allowed level. METHODS : The methodology used are basically the relationship between emission rates and vehicle speeds or acceleration rate. These rates together are used to calculate the added $CO_2$ emissions incurred from accelerating operation. RESULTS : It was resulted that the all the emission rates are increasing proportionally to vehicle speeds or acceleration rates. Additionally, it was also resulted that allowable speeds increasing, the added emission rates are increasing rapidly. CONCLUSIONS : It may be concluded that if the allowable speed ranges are managed, $CO_2$ emissions during vehicle operation are much reduced. From this reason, it was found that the allowable speed during highway design and operation would be much necessary

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.150-155
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• 2015

Recently, LNG receiving terminals have been widely constructed and expanded for an increase in LNG demand. Selection of the storage tank for send-out and estimation of send-out flow rate have significant influence to process operation and economics. In this study, a send-out flow rate of each storage tank is optimized in order to minimize the total BOG generation rate. Considering a size and characteristic of each storage tanks, BOG flow rates are estimated using a dynamic simulation with varying liquid levels in the tanks. The regression model is developed fitting BOG flow rates and tank liquid levels, which are boil off rate model to predict BOG flow rates with particular level data. The objective function and constraints including required total send-out flow rate and level limit in the tanks are formulated to optimize a send-out flow rate of each tank. This method for optimization of send-out operation is applied to the Incheon LNG receiving terminal considering two scenarios for various liquid levels and maximum and minimum required send-out flow rates. For maximum required send-out flow rate, this method achieves BOG reduction of 9% comparing with assumed conventional operation.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.289-299
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• 2013

Objectives: For the field application of the dielectric barrier discharge plasma reactor, scale-up of the plasma reactor is needed. This study investigated the possibility of inactivation of microorganisms in sewage using pilot multi-plasma reactor. We also considered the possibility of degradation of total organic carbon (TOC) and nonbiodegradable matter ($UV_{254}$) in sewage. Methods: The pilot plasma reactor consists of plasma reactor with three plasma modules (discharge electrode and quartz dielectric tube), liquid-gas mixer, high voltage transformers, gas supply equipment and a liquid circulation system. In order to determine the operating conditions of the pilot plasma reactor, we performed experiments on the operation parameters such as gas and liquid flow rate and electric discharge voltage. Results: The experimental results showed that optimum operation conditions for the pilot plasma reactor in batch experiments were 1 L/min air flow rate), 4 L/min liquid circulation rate, and 13 kV electric discharge voltage, respectively. The main operation factor of the pilot plasma process was the high voltage. In continuous operation of the air plasma process, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal condition of 13 kV were $10^{2.24}$ CFU/mL, 56.5% and 8.6%, respectively, while in oxygen plasma process at 10 kV, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal conditions were $10^{1.0}$ CFU/mL, 73.3% and 24.4%, respectively. Electric power was increased exponentially with the increase in high voltage ($R^2$ = 0.9964). Electric power = $0.0492{\times}\exp^{(0.6027{\times}lectric\;discharge\;voltage)}$ Conclusions: Inactivation of microorganisms in sewage effluent using the pilot plasma process was done. The performance of oxygen plasma process was superior to air plasma process. The power consumption of oxygen plasma process was less than that of air plasma process. However, it was considered that the final evaluation of air and oxygen plasma must be evaluated by considering low power consumption, high process performance, operating costs and facility expenses of an oxygen generator.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.137-147
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• 2017

Wartime warship damage rate indicates how much damage of friend warships shall have occurred during naval battles accomplished under specific war operational plans. The wartime damage rate analysis provides the baseline of wartime resources requirements. If wartime damage rate is overestimated, the national finance will get to negative effects because of exceeding the budget for inventory, operation, and maintenance of resources. Otherwise, if wartime damage rate is underestimated, the national defense will lose in the war because of lack of critical resources. In this respect, it is important to estimate the wartime damage rate accurately and reasonably. This paper proposes a systematic procedure to estimate the wartime warship damage rate. The procedure consists of five steps; force analysis, operation plan analysis, input variable definition, simulation modeling, and output analysis. Since the combat simulation model is regarded as the main tool to estimate damage rate, the procedure is focused on the development of model and experiments using the model. A case study with virtual data is performed to demonstrate the effectiveness of the developed procedure.

• Journal of Environmental Science International
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• v.23 no.9
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• pp.1601-1608
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• 2014

Plasma reactor was used for the inactivation of Phytophthora capsici which is phytophthora blight pathogen in aquiculture. Effects of first voltage, second voltage, air flow rate, pH, incubation water concentration were examined. At the low $1^{st}$ voltage, under 80 V, the lag phase was noticed within 30 sec, however, it was not shown over 100 V. The variation of optimum operation condition was not shown by the variation of microorganisms. However, the inactivation rate was different by the variation of species of microorganisms. The inactivation rate and efficiency were increased by the increase of $2^{nd}$ voltage. The highest initial inactivation rate was shown at pH 3 and the rate was decreased by the increase of pH. The inactivation rate increased by the increase of air flow rate, however, it was shown as similar at the rate of 4 L/min and 5 L/min. The inactivation rate was distinctly decreased at the three times concentration of incubation solution comparing at the distilled water and basic incubation solution.

• Journal of the Korean Society of Combustion
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• v.20 no.3
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• pp.35-42
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• 2015

Investigating coal combustion in a large-scale boiler using computational fluid dynamics (CFD) requires a combination of flow and reaction models. These models include a number of rate constants which are often difficult to determine or validate for particular coals or furnaces. Nonetheless, CFD plays an important role in developing new combustion technologies and improving the operation. In this study, the model selection and rate constants for coal devolatilization, char conversion, and turbulent reaction were evaluated for a commercial wall-firing boiler. The influence of devolatilization and char reaction models was found not significant on the overall temperature distribution and heat transfer rate. However, the difference in the flame shapes near the burners were noticeable. Compared to the coal conversion models, the rate constant used for the eddy dissipation rate of gaseous reactions had a larger influence on the temperature and heat transfer rate. Based on the operation data, a value for the rate constant was recommended.

• Journal of environmental and Sanitary engineering
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• v.23 no.4
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• pp.73-82
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• 2008

In this study, a dry single-phase anaerobic digestion process (Dranco system) was investigated to evaluate the optimum operational conditions. Several factors such as injection rate of organic waste, biogas production, $CH_4$ content in the biogas, pH of the sludge, $NH_3$-N and VFA concentration were investigated based on the operation of the digestion process for 2 months (short term) and 8 months (long-term). The operation results showed that a small quantity of food waste should be injected every week and that a 10% increase of the microorganism injection rate should be needed. However, normal operation was conducted after 11 weeks based on the designed quantity. The $CH_4$ content in the biogas was high at the beginning and the end of the food injection. However, it was low during week days. When the biogas production was high, the $CH_4$ concentration was low. The biogas production increased with an increase of the injection rate. $100m^3$/ton of biogas was produced from normal operation of the digestion process based on the designed quantity. The pH values of the digestion tank based on short-term operation ranged from 8 to 8.5. However, the pH values ranged from 7.45 to 8.15 after 4 weeks of long-term operation. The $NH_3$-N concentration of short-term operation ranged from 4,500 to 5,500 ppm and it gradually decreased to 2,000ppm after normal operation was commenced. For long-term operation, it was 5,000ppm initially and 3,800ppm after normal operation was commenced. The VFA concentration of sludge was less than 900ppm and 2,500ppm for short and long-term operations, respectively, after normal operation. Overall, the differences between sludge pH, $NH_3$-N and VFA concentrations may be due to the different types of microorganisms and the digestion ability of the microorganisms which exist in the accumulation of non digested organics. Moreover, it may be also caused by the type of food waste. Further investigation is needed to confirm these relationships.