• Nuclear Engineering and Technology
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• v.5 no.4
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• pp.291-309
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• 1973

Exposure rates due to leakage gamma-rays from operating reactors TRIGA Mark II and III were measured in a horizontal plane by means of scintillation spectrometry using a 3"$\times$3" cylindrical Nal(T1) detector associated with a 400 channel pulse height analyzer under varied conditions of reactor operation. In determining exposure rate due to the leakage gamma-rays at each point of measurement, Moriuchi's spectrum-exposure rate conversion theory was applied instead of using conventional responce matrix method which necessitates very complicated procedures to convert a spectrum into exposure rate. The results show that a basic pattern of "typical" spectrum of the reactor leakage gamma-rays is neither affected by thermal output of the reactor, nor influenced by overall attenuation in radiation intensity. It was indicated that he attenuation of the leakage gamma-rays in air in terms of exposure rate as a whole follows an exponential law, and the total exposure rate due to the leakage gamma-rays at a certain point is nearly proportional to thermal output of the reactor. The complexity in spectrum measured for a movable core reactor, TRIGA Mark III, was analyzed through spectrum resolution, and proper judgement of the leakage gamma-rays in a complex spectrum was discussed.ctrum was discussed.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.49-54
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• 2016

The large scaled lead-acid battery is widely used for efficient operation of the photovoltaic system in many islands. However, lithium-ion battery is now being introduced to mitigate the fluctuation of wind power and to replace lead-acid battery. Therefore, hybrid ESS (Energy Storage system) that combines lithium-ion battery with lead-acid battery is being required because lithium-ion battery is costly in present stage. Under this circumstance, this paper presents the optimal algorithm to create composition rate of hybrid ESS by considering fixed and variable costs in order to maximize advantage of each battery. With minimization of total cost including fixed and variable costs, the optimal composition rate can be calculated based on the various scenarios such as load variation, life cycle and cost trend. From simulation results, it is confirmed that the proposed algorithms are an effective tool to produce a optimal composition rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.920-926
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• 2011

In this paper, a solar power emotional LED lightening street lamps with multi control sun tracker is presented. The proposed system has a multiple control sun tracking function and high quality emotional LED lamps. The system is designed to absorb maximum sun lights by temperature sensor and humidity sensor of control circuits. A battery charge-discharge controller is developed for high efficient usage of battery charger for utilization of new and renewal energy. An interface circuit for remote monitoring and controlling is included in the developed system. The proposed multi tracking solar power emotional LED street lamps is better than conventional systems in aspect of tracking operation and energy efficiency, and expected to be a leading model for next generation solar power street lamp system, because it is a new technology combining sun tracking solar power system and emotional lightening system.

• Clinical Nutrition Research
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• v.5 no.4
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• pp.279-289
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• 2016

The adequate dietary intake is important to maintain the nutritional status of the patients after pancreatic cancer surgery. This prospective study was designed to investigate the dietary intake and the nutritional status of the patients who had pancreatic cancer surgery. Thirty-one patients (15 men, 16 women) were enrolled and measured body weight, body mass index (BMI), nutritional risk index (NRI), and Malnutrition Universal Screening Tool (MUST). Actual oral intake with nutritional impact symptoms recorded on the clinical research foam at every meal and medical information were collected from electronic medical charts. The rates of malnutrition at admission were 45.1% (14/31) and 28.9% (9/31) by NRI and MUST method, respectively, but those were increased to 87% (27/31) and 86.6% (26/31) after operation on discharge. The median values of daily intake of energy, carbohydrates, fat, and protein were 588.1 kcal, 96.0 g, 11.8 g, and 27.0 g, respectively. Most patients (n = 20, 64.5%) experienced two or more symptoms such as anorexia, abdominal bloating and early satiety. There were negative correlations between C-reactive protein (CRP) levels and the intake of total energy, protein, fat, and zinc. The rates of malnutrition were increased sharply after surgery and the dietary intake also influenced the inflammatory indicators. The results suggested that need of considering special therapeutic diets for the patients who received pancreatic surgery.

• Journal of Environmental Science International
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• v.32 no.8
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• pp.555-561
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• 2023

A study is to predict the effective pulsing distance following to the pulsing pressure, nozzle diameter, filtration velocity using numercial analysis techniques and use it as an efficient operation condition and economic data for on-line type pulse air jet bag filter. Filtration area 6 m² condition, calculate filter resistance coefficient for simulation through the primary experiments using coke dust. For CFD simulation, analysis pulsing characteristics about nozzle diameter, filtration velocity and pulsing pressure. The maximum pulsing length of on-line type pulse air jet bag filter, in 10mm nozzle, filtration velocity 1.5m/min and pulsing pressure 5 bar conditions, is 2,285 mm, maximum length is 76.2% of the total filter bag, which is sufficient to pulsing. In 12mm nozzle, pulsing pressure 5 bar and filtration area 1.22 m² conditions, the maximum pulsing length of on-line type pulse air jet bag filter is 1,744~2,952 mm, and the maximum length is 2,952 mm indicates pulsing air can be reached to the bottom of filter bag. When the nozzle diameter is increased 8mm to 10mm, maximum pulsing length is extended 40~47%, and increased 10mm to 12 mm, maximum pulsing length is extended 10~17%. For effective pulsing, over the 5bar of pulsing pressure and larger than 10 mm of nozzle diameter are required.

• Membrane Journal
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• v.32 no.1
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• pp.66-73
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• 2022

In this study, a method for stabilizing treated water was conducted while maintaining high flux using a metal flat membrane module made of stainless steel. This module had a pore size of 13 ㎛, so it was possible to operate at a high flux from 60 LMH to 100 LMH. However, although SS leaked about 30~50 ppm during initial operation, aggregation was possible because SS acted as aggregation nucleus. While polymer membrane permeate does not have aggregation nucleus, so coagulation is possible but not flocculation. Typically clay or bentonite, which is used as aggregation nucleus, is additionally administered. In this study, the total phosphorus treatment and the quality of the treated water were to promote stability because flocculation was achieved only with SS leakage without the need for such a aggregation nucleus. Finally, the feasibility of operating a metal membrane filter capable of high flux in stable treated water to be applied to the MBR system.

• Journal of Wind Energy
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• v.15 no.1
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• pp.21-29
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• 2024

In order to respond to environmental changes and various events in the nearby sea area due to the operation of an offshore wind substantiation farm in the Southwest Sea, X-band radar has been installed and operated on a fixed platform since 2018. The X-band radar's monitoring system produces wave and current data through Rutter's Ocean WaveS wave and current (Sigma S6 WaMoS II). In this study, to verify the reliability of the produced data, the accuracy of current and wave data was evaluated by analyzing the correlation with the results obtained by an acoustic doppler current profiler (ADCP). The selected analysis period was a total of 30 days from November 29 to December 28, 2021, the period during which the ADCP survey was conducted. As a result of comparative verification, the current, wave height and peak wave period (H_s > 0.69 m) data observed from the X-band radar showed a high correlation with the results investigated from ADCP. In the future, current and wave data produced by X-band radar are expected to be used as basic data to analyze environmental changes in sea areas and provide information on various events.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.50-56
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• 2007

FAO standard for heat sterilization of wood, International standards for phytosanitary measures (ISPM) No.15, must meet heat-treated wood core temperature to be higher than $56^{\circ}C$ and keep the temperature for more than 30 minutes. This study was carried out to analyze the heat treatment characteristics of domestic pinewood sterilized with the FAO standard. To enhance the effectiveness of heat treatment process in mountainous district energy consumption and time required to reach target temperature were evaluated at various temperature and relative humidity conditions and moisture contents of wood. Heat-treatment of high temperature and high humidity reduced the required heating time. Lower humidity levels at same temperature reduced energy consumption per unit time. However, lower humidity levels could not reduce total energy consumption greatly because longer treatment time was required at that condition. It is necessary to estimate energy consumption and predict treatment time in dynamic heating and cooling situations, because it frequently happens not to meet optimum treatment condition due to poor surrounding climates and operation performance of heat treatment facility in real field.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4571-4584
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• 2022

The analysis of rapid flow transients in Reactor Coolant Pumps (RCP) is essential for a reactor safety study. An accurate and precise analysis of the RCP coastdown is necessary for the reactor design. The coastdown of RCP affects the coolant temperature and the colloidal crud in the primary coolant. A realistic and kinetic model has been used to investigate the behavior of activated colloidal crud in the primary coolant and steam generator that solves the pump speed analytically. The analytic solution of the non-dimensional flow rate has been determined by the energy ratio β. The kinetic energy of the coolant fluid and the kinetic energy stored in the rotating parts of a pump are two essential parameters in the form of β. Under normal operation, the pump's speed and moment of inertia are constant. However, in a coastdown situation, kinetic damping in the interval has been implemented. A dynamic model ACCP-SMART has been developed for System Integrated Modular and Advanced Reactor (SMART) to investigate the corrosion due to activated colloidal crud. The Fickian diffusion model has been implemented as the reference corrosion model for the constituent component of the primary loop of the SMART reactor. The activated colloidal crud activity in the primary coolant and steam generator of the SMART reactor has been studied for different equilibrium corrosion rates, linear increase in corrosion rate, and dynamic RCP coastdown situation energy ratio b. The coolant specific activity of SMART reactor equilibrium corrosion (4.0 mg s^-1) has been found 9.63×10^-3 µCi cm^-3, 3.53×10^-3 µC cm^-3, 2.39×10^-2 µC cm^-3, 8.10×10^-3 µC cm^-3, 6.77× 10^-3 µC cm^-3, 4.95×10^-4 µC cm^-3, 1.19×10^-3 µC cm^-3, and 7.87×10^-4 µC cm^-3 for ²⁴Na, ⁵⁴Mn, ⁵⁶Mn, ⁵⁹Fe, ⁵⁸Co, ⁶⁰Co, ⁹⁹Mo, and ⁵¹Cr which are 14.95%, 5.48%, 37.08%, 12.57%, 10.51%, 0.77%, 18.50%, and 0.12% respectively. For linear and exponential coastdown with a constant corrosion rate, the total coolant and steam generator activity approaches a higher saturation value than the normal values. The coolant and steam generator activity changes considerably with kinetic corrosion rate, equilibrium corrosion, growth of corrosion rate (ΔC/Δt), and RCP coastdown situations. The effect of the RCP coastdown on the specific activity of the steam generators is smeared by linearly rising corrosion rates, equilibrium corrosion, and rapid coasting down of the RCP. However, the time taken to reach the saturation activity is also influenced by the slope of corrosion rate, coastdown situation, equilibrium corrosion rate, and energy ratio β.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.79-84
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• 2013

DC/DC switching power converters are commonly used to generate a regulated DC output voltage with high efficiency. The DC/DC converter is composed of a PWM-IC (pulse width modulation-integrated circuit) controller, a MOSFET (metal-oxide semiconductor field effect transistor), inductor, capacitor, etc. It is shown that the variation of threshold voltage and the offset voltage in the electrical characteristics of PWM-IC increase by radiation effects in TID (Total Ionizing Dose) testing at the low energy ${\gamma}$ rays using $^{60}Co$, and 4 heavy ions applied for SEL (Single Event Latch-up) make the PWM pulse unstable. Also, the output waveform for the given input in the DC/DC converter is observed by the simulation program with integrated circuit emphasis (SPICE). TID testing on PWM-IC is accomplished up to the total dose of 30 krad, and the cross section($cm^2$) versus LET($MeV/mg/cm^2$) in the PWM operation is studied at SEL testing after implementation of the controller board.