• Nuclear Engineering and Technology
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• v.38 no.2
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• pp.185-194
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• 2006

Transient operations for an integral type reactor, SMART-P, have been experimentally investigated using a thermal-hydraulic integral test facility, VISTA (Experimental Verification by Integral Simulation of Transients and Accidents), in order to verify the system design and performance of the SMART-P, a pilot plant of SMART. The VISTA facility was subjected to various accident conditions such as feedwater increase and decrease, loss of coolant flow, and control rod withdrawal accidents in order to elucidate the thermal-hydraulic responses following such accidents and finally to verify the system design of the SMARTP. Full functional control logics have been implemented in the VISTA facility in order to control the required control action for an accident simulation. As one of the sensitivity tests to verify the PRHRS performance, the effects of the initial water level in the compensation tank are experimentally investigated. When the initial water level is 16%, the water is quickly drained and nitrogen gas is then introduced into the PRHR system, resulting in deterioration of the PRHRS performance. It is thus found that nitrogen ingression should be prevented to ensure stable PRHRS operation.

• Journal of Korea Water Resources Association
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• v.37 no.8
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• pp.653-662
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• 2004

In this study, the method of Increasing the flood control as well as conservation effects is studied by joint operation of Hwacheon and Peace Dam. After completing the second phase of the construction of the Peace Dam, the dam crest height will be increased from 225m and the storage capacity will also be increased. If storage capacity is increased and gates are installed, it will assist not only flood control but also conservation of the entire Han river basin. Considering the change of conservation levels, the change of the restricted water level of the Hwacheon Dam in flood season, and the inflow change into the Peace Dam through the simulated reservoir operation, the annual average power of Hwacheon Dam with 95% reliability, annual firm power, the volume of water supply is calculated. As a result, when the conservation level of the Peace Dam and the restricted water level of the Hwacheon Dam are increased, the generation capacity will be improved. However, even though the inflow decrease, the generation capacity will not be affected. If the inflow decrease under the same conditions, the water supply capability will be reduced to the range from 35% to 40%. It is necessary to increase conservation level to keep the same water supply capability.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.6
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• pp.63-72
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• 2020

With the implementation of integrated water management policies, the need for information sharing with respect to agricultural water use has increased, necessitating the quantification of irrigation water supply using monitoring data. This study aims to estimate the irrigation water supply amount based on the relationship between the water level and irrigation canal discharge, and evaluate the reliability of monitoring data for irrigation water supply in terms of hydrology. We conducted a flow survey in a canal and reviewed the applicability of the rating curve based on the exponential and parabolic curves. We evaluated the reliability of the monitoring data using a reservoir water balance analysis and compared the calculated results of the supply quantity in terms of the reservoir water reduction rate. We secured 26 readings of measurement data by varying the water levels within 80% of the canal height through water level control. The exponential rating curve in the irrigation canal was found to be more suitable than the parabolic curve. The irrigation water supplied was less than 9.3-28% of the net irrigation water from 2017 to 2019. Analysis of the reservoir water balance by applying the irrigation water monitoring data revealed that the estimation of the irrigation water supply was reliable. The results of this study are expected to be used in establishing an evaluation process for quantifying the irrigation water supply by using measurement information from irrigation canals in agricultural reservoirs.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.230-243
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• 1996

Root surface exposure due to gingival recession after periodontal surgery, dentin exposure after root planing elicit pain response when exposed to mechanical, heat, chemical or osmotic stimulation. Especially, patients treated with periodontal surgery, show high frequency and there have been reports showing the 1 out of 7 patients have dentin hypersensitivity. There have been many studies on the clinical effects of various materials on the treatment of dentin hypersensitivity. but, none could provide absolute clinical efficacy. In this study, 45 teeth from 30 patients, who had had periodontal surgery and showed dentin hypersensitivity after surgery were chosen for the experimental group and they were illuminated with laser, 15teeth were chosen for the control group and they were not exposed to laser. After this dentin hypersensitivity was elicited by tactile, compressed air, cold water and then, the degree was evaluated using NRS(Numerical Rating Scale). And during LLLT(Low Level Laser Therapy) semiconductor laser using Gallium - Arsenide as a diode was illuminated for 180 seconds at a frequency of 7(500Hz). This therapy was done 10 times, and each time the changes in dentin hypersensitivity was evaluated using NRS. The results were as follows : 1. After treat with LLLT on dentin hypersensitivity due to periodontal surgery, 22.2% showed total loss of dentin hypersensitivity, 60.0% showed loss of tactile dentin hypersensitivity, 48.8% showed loss of compressed air dentin hypersensitivity, 22.2% showed loss of cold water dentin hypersensitivity. 2. As a result of clinical evaluation of dentin hypersensitivity using NRS, there was significant increase in improvement of dentin hypersensitivity in the experimental group compare to the control group(P<0.05). And there was almost no natural loss of dentin hypersensitivity in the control group. 3. In comparison of the stages of evaluation, there was significant difference in between experimental and control group. after the second visit(P<0.05), and the difference increased with each visit.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.2
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• pp.121-132
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• 2018

Along with climate change, it is reported that the extreme climate events such as severe drought could cause difficulties of agricultural water supply. To minimize such damages, it is necessary to secure the agricultural water resources by using or saving the amount of irrigation water efficiently. The objectives of this study were to develop paddy water management scenarios and to evaluate their effectiveness on water saving. Three water management scenarios (a) deep irrigation with ponding depth of 20~80 mm (control, CT), (b) no/intermittent irrigation until paddy cracks (water management A, WM-A), and (c) intermittent irrigation with ponding depth under 20 mm (water management B, WM-B) were developed. Water saving effects were analyzed using monitored data from experimental paddy fields, and agricultural water supply was analyzed on a reservoir-scale using MASA model. The observed irrigation amounts were reduced by 21 % and 17 % for WM-A and WM-B compared to CT, respectively, and mainly occurred by the increase of effective rainfall. The simulation results showed that water management scenarios could reduce irrigation by 21~51 % and total inflow by 10~24 % compared to CT. The long-term simulated water level change of agricultural reservoir resulted in the decrease of dead level occurrence for WM-A and WM-B. The study results showed that WT-A and WT-B have more benefit than CT in the aspect of agricultural reservoir water supply.

• Korean Journal of Veterinary Service
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• v.24 no.4
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• pp.379-382
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• 2001

To confirm the effect of food and water deprivation prior to Newcastle disease(ND) virus vaccination, three hundred chicks were divided into five groups with three replications. ND vaccine were sprayed to at 1 -day old chicks at commercial hatchery. Secondary and third vaccination was conducted at 2-week old and 24-day old chicks by LaSota strain. Control was conventionally vaccinated without withdrawing the food and water before or after vaccination. In group 2(G2) and 3(G3), LaSota strain was vaccinated to chicks before and after fasting the food and water for 3 and 2 hours, respectively. Group 4(G4) has the same fasting time of group 2, but supplemented the skim milk in vaccin dilution water. In group 5(G5), skim milk was added into group 3. Weight gain, feed intake and feed conversion were weekly measured for 5 weeks. Blood was collected from wing vein at 24 and 35 days of age. Each serum antibody level were measured by hemagglutination inhibition(HI) test. The average weight gain, feed intake, feed conversion of all group were not significantly different. Weight gain of each groups was 1910.30(control), 1875.28(G2), 1952.12(G4) and 1896.05(G5), respectively. Feed intake of all group was recorded at 3160.67(control), 3167.07(G2), 3189.48(G3), 3157.85(G4) and 3178.16(G5), respectively. The feed conversion of each groups was 1.655(control), 1.688(G2), 1.633(G3), 1.699(G4) and 1.676(G5), respectively. The HI titer of G4 was $ 5.50{\Pm}$1.40 and significantly higher than the other groups (p<0.05)(control : $4.36{\Pm}$1.87 , G2 : $5.18{\Pm}$2.14, G3 : $4.51{\Pm}$2.19, G : $5.28{\Pm}$1.58 at 35 days old. The results of this experiment indicated that two or three hours of fasting time before or after vaccination would be able to show the higher antibody level against ND virus.

• Journal of Nutrition and Health
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• v.29 no.6
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• pp.615-621
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• 1996

Experiments were carried out in humans to assess the relationship between viscosity and post-prandial glucose response of soluble fibers. Eight(3 male and 5 female) healthy individuals were tested for their glucose response after taking control meals or 3 test fiber meals of different viscosities. Meal viscosity of the test food was adjusted to be between 200 and 70, 000 cps. There was a significant increase in post-prandial glucose response(p=0.01) in control meals by solely increasing the volume of water. Fiber with the highest viscosity konjac mannan demonstrated the lowest relative glucose response(70.1$\pm$6.6), followed by medium viscosity xanthan (79.3$\pm$8.7)and low viscosity psyllium (86.3$\pm$10.5). The difference is significant at the level of p<0.05. However, no significant difference in relative glucose response of the same fiber was found when the 4 levels of water were added to make different meal viscosity of each fiber (p=0.476). This result suggested that hypoglycemic action of soluble dietary fibers is related to fiber viscosity rather than meal viscosity.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.4
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• pp.45-51
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• 1991

The objective of this paper is to show how the fuzzy sets theory can be applied to the reservoir operation guidelines for agricultural purposes. The concepts of the theory has been resented as a new tool for the decision problems which contains fuzziness and it's application can be found in operations research, expert systems, robotics, fuzzy computers, and pattern recognition. The fuzzy control system for the reservoir operation composed of a set of reservoir operation rules and a fuzzy inference engine was built. Water demand for paddy fields, water availability, and inflow to a reservoir were selected as main factors which determine the magnitude of reservoir release. The behavior of the control system was evaluated for different level of water demand and the results seemed to be reasonable.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.877-885
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• 2018

Various controllers such as proportional-integral-derivative (PID) controllers have been designed and optimized for load-following issues in nuclear reactors. To achieve high performance, gain tuning is of great importance in PID controllers. In this work, gains of a PID controller are optimized for power-level control of a typical pressurized water reactor using particle swarm optimization (PSO) algorithm. The point kinetic is used as a reactor power model. In PSO, the objective (cost) function defined by decision variables including overshoot, settling time, and stabilization time (stability condition) must be minimized (optimized). Stability condition is guaranteed by Lyapunov synthesis. The simulation results demonstrated good stability and high performance of the closed-loop PSO-PID controller to response power demand.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.1 s.12
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• pp.41-50
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• 2004

The objective of this study is to investigate the feasibility of the developed Fuzzy control techniques in dam operation. The simulated results for the 1984, 1990, and 1995 flood events are compared with historical operation results in the view of flood control and disaster prevention. The three models developed in this study determine the outflows based on the two conditions the first one is to consider only two inputs such as reservoir water level and inflow, for operation of the existing situations, the second one is that the possible maximum discharge from each dam does not exceed the allowable design maximum discharge for disaster prevention in downstream area. As the results, it was shown that the suggested models based on Fuzzy control technique could reduce both the peak water level and the maximum peak discharge compared with the historical operation results.