• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.523-529
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• 2020

Power distribution management system is essential for the efficient management and operation of power distribution networks. The power distribution system is a system that manages the distribution network based on IT, and has been evolving along with the development of the power industry. The current power distribution system is designed to operate at a relatively low network transmission speed based on the independent operation of the main equipment. However, due to distributed resources such as photovoltaic or energy storage devices, which are rapidly increasing in popularity in recent years, the operation of future distribution environments is becoming more complex, and various information needs to be collected in real time. In this study, the requirements of the next-generation power distribution system were derived to overcome the limitations of the existing power distribution system, and based on this, the communication network system and performance requirements for the distribution system were defined. In order to verify the performance of the designed system, a software-based terminal device simulator was developed because it takes excessive time and cost to introduce a large-scale system such as a power distribution system. Using the simulator, a test environment similar to the actual operation was established, and the number of terminal devices was increased up to 1,000. The proposed system was shown to satisfy the requirements to support the functions of the next-generation power distribution system, recording less than 10 % of the communication network bandwidth.

• Korean Journal of Construction Engineering and Management
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• v.23 no.6
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• pp.30-42
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• 2022

OSC is a type of supply chain and value chain that spans the entire process of construction production (planning, design, construction, maintenance, etc.). It is a method of producing the final object by manufacturing it in a factory, transporting it to the site, installing and construction. This research as is the construction cost was compared for each case A, which applied the PC method, and case B, which applied the RC method. In the case of applying the PC method (excluding the PC design cost), compared to the case where only the RC method was applied, the frame construction cost per unit quantity (m³) increased by about 70% (50% based on the total RC construction type). Of the total frame construction cost of PC method application, PC accounted for 90.2%, 'PC manufacturing cost' 54.8%, 'PC assembly cost' 28.5%, and 'transportation cost' accounted for 6.89%. Also a decision-making framework that can consider both costs and benefits was established. In the case of benefits, the construction period, defect repair, disaster occurrence, energy efficiency, noise/dust/waste, and greenhouse gas emission indicators reflecting OSC technical advantages were presented. It can contribute to providing a basis for helping decision-making on the introduction of PC apartment houses using OSC.

• Journal of Wetlands Research
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• v.24 no.4
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• pp.345-353
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• 2022

A wastewater treatment plant (WWTP) is a major gateway for the engineered nano-particles (ENPs) entering the water bodies. However existing studies have reported that many WWTPs exceed the No Observed Effective Concentration (NOEC) for ENPs in the effluent and thus they need to be designed or operated to more effectively control ENPs. Understanding and predicting ENPs behaviors in the unit and \the whole process of a WWTP should be the key first step to develop strategies for controlling ENPs using a WWTP. This study aims to provide a modeling tool for predicting behaviors and removal efficiencies of ENPs in a WWTP associated with process characteristics and major operating conditions. In the developed model, four unit processes for water treatment (primary clarifier, bioreactor, secondary clarifier, and tertiary treatment unit) were considered. Additionally the model simulates the sludge treatment system as a single process that integrates multiple unit processes including thickeners, digesters, and dewatering units. The simulated ENP was nano-sized TiO₂, (nano-TiO₂) assuming that its behavior in a WWTP is dominated by the attachment with suspendid solids (SS), while dissolution and transformation are insignificant. The attachment mechanism of nano-TiO₂ to SS was incorporated into the model equations using the apparent solid-liquid partition coefficient (Kd) under the equilibrium assumption between solid and liquid phase, and a steady state condition of nano-TiO₂ was assumed. Furthermore, an MS Excel-based user interface was developed to provide user-friendly environment for the nano-TiO₂ removal efficiency calculations. Using the developed model, a preliminary simulation was conducted to examine how the solid retention time (SRT), a major operating variable affects the removal efficiency of nano-TiO₂ particles in a WWTP.

• Journal of Animal Science and Technology
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• v.45 no.4
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• pp.569-576
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• 2003

An experiment was conducted to investigate the effect of microbial phytase (Natuphos$^{\circledR}$) supplementation, individually and in combination with carbohydrase enzyme complex (composed of enzymes targeted to SBM dietary components such as $\alpha$-galactosides and galactomannans; ENDO-POWER$^{\circledR}$) to corn-soy basis diet with low nutrient levels on growth performance and nutrient digestibility of growing pigs. A total of 48 crossbred weaned pigs (Landrace${\times}$Yorkshire${\times}$Duroc), 29.1$\pm$0.14 kg of initial body weight, were randomly allotted to four dietary treatments, based on weight and age, according to a Randomized Complete Block Design. There were three pens per treatment and 4 pigs per pen. The dietary treatments were 1) CON (control diet with 3,380 kcal/kg of metabolizable energy, 18.96% of crude protein, 1.10% of lysine, 0.75% of calcium and 0.35% of available phosphorus), 2) LP+NTPS (CON diet with 0.15% unit lower available P levels+0.1% phytase (500 FTU/kg; Natuphos$^{\circledR}$)), 3) LEL+ENP (CON diet with 3.0% unit lower ME and lysine levels + 0.1% carbohydrase enzyme complex (ENDO-POWER$^{\circledR}$), and 4) LPEL+ENZ (CON diet with 0.15% unit lower available P levels and 3.0% unit lower ME and lysine levels+0.1% ENDO-POWER$^{\circledR}$ and 0.1% Natuphos$^{\circledR}$ (500 FTU/kg). There was no significant difference (p〉0.05) in average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) among dietary treatments during the whole experimental period (0 to 4 weeks). Apparent digestibility of gross energy was greater in LP+NTPS and LPEL+ENZ groups than in the LEL+ENP (p<0.05). Apparent digestibility of phosphorus was greater in LP+NTPS than in LEL+ENP (p<0.05). Dry matter excretion was lowest in LPEL+ENZ and phosphorus excretion was lowest in LP+NTPS (p<0.05). Overall, pigs fed on LPEL+ENZ group tended to have better nutrient digestibility (dry matter, gross energy, crude protein and phosphorus) than pigs fed on control group. All dietary enzyme treatment groups showed lower feed cost/body weight gain of pigs than control group. In conclusion, the results from the present study suggest that the simultaneous inclusion of phytase and carbohydrase enzyme complex to diets is advantageous with respect to reducing nutrient excretion of growing pigs and may contribute to increased economic return when added to corn-soy based growing pig diets.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.407-414
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• 2016

This study was conducted to investigate the effects of supplementation of dietary betaine on nutrient digestibility and physiological responses in finishing pigs. A total of twelve pigs with a body weight of $80.1{\pm}3.7kg$ were individually caged, and randomly assigned to one of the two experimental diets containing 0 (control) or 5 g/kg (treatment) of the betaine in a $2{\times}2$ Latin square design. The experimental period was 14 days-7 days adaptation and 7 days trial period-per phase. All data for the difference between control and treatment groups were statistically analyzed by student's t-test. Dry matter and crude protein digestibility in the treatment group were significantly improved by 1% and 1.3%, respectively, as compared with those in the control (p<0.05). The apparent absorption of dietary energy was increased from 82.3% to 83.7% by dietary betaine supplementation. Thus, the retention of energy was also significantly increased to above 6% in the treatment group compared with the control group (control 4,057 vs treatment 4,314 kcal; p<0.01). The physiological parameters indicating serum biochemical contents and stress-, immune-, and inflammatory- responses were not changed by the supplementation of dietary betaine. In conclusion, dietary betaine improves the nutrient digestibility without any negative effects in terms of physiology in finishing pigs. It suggests that the supplementation of dietary betaine may increase the productivity through the improvement of weight gain and feeding efficiency.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.5
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• pp.587-609
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• 2019

Short-and long-term stabilities of bentonite, favored material as buffer in geological repositories for high-level waste were reviewed in this paper in addition to alternative design concepts of buffer to mitigate the thermal load from decay heat of SF (Spent Fuel) and further increase the disposal efficiency. It is generally reported that the irreversible changes in structure, hydraulic behavior, and swelling capacity are produced due to temperature increase and vapor flow between $150{\sim}250^{\circ}C$. Provided that the maximum temperature of bentonite is less than $150^{\circ}C$, however, the effects of temperature on the material, structural, and mineralogical stability seems to be minor. The maximum temperature in disposal system will constrain and determine the amount of waste to be disposed per unit area and be regarded as an important design parameter influencing the availability of disposal site. Thus, it is necessary to identify the effects of high temperature on the performance of buffer and allow for the thermal constraint greater than $100^{\circ}C$. In addition, the development of high-performance EBS (Engineered Barrier System) such as composite bentonite buffer mixed with graphite or silica and multi-layered buffer (i.e., highly thermal-conductive layer or insulating layer) should be taken into account to enhance the disposal efficiency in parallel with the development of multilayer repository. This will contribute to increase of reliability and securing the acceptance of the people with regard to a high-level waste disposal.

• Journal of Aquaculture
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• v.14 no.3
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• pp.197-203
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• 2001

To replace fish meal (FM) in the diet of Nile tilapia, Oreochromis nloticus, different levels of Iysine cell mass (LCM) were added to diet on protein equivalent base. fish averaging 3.0 g fed one of nine diets containing isonitrogenous and isocaloric basis of 35% crude protein and 15.3kJ available energy/g diet: $LCM_0, 100% FM: LCM_{10}, 90% FM+10% LCM, LCM_{20}, 80% FM+20% LCM; LCM_{30}, 70% FM+30% LCM; LCM_{40}, 60% FM+40% LCM; LCM_{30}l, 70% FM+30% LCM+lysine; LCM_{30}ln, 70% FM +30% LCM + lysine +NaOH; LCM_{40}lan, 60% FM+40% LCM+lysine+arginine; LCM_{40}/lan, 60% FM+40% LCM+lysine+arginine+NaOH.$. After 8 weeks of feeding trial, there were no significant differences in weight gain (WG) and specific growth rate (SGR) among fish fed LCM$_{0}$ (control diet), LCM_{10}, LCM_{30}, LCM_{40}, LCM_{30}l, LCM_{30}ln, LCA_{40}la and LCM_{40}lan diets (P>0.05)$, while fishes fed $LCM_{20} diet were significantly higher than those fed LCM_{0}, LCM_{30}, LCM_{40}, LCM_{40}la and LCM_{40$}lan diets (P<0.05). There were no significant differences in feed efficiency (FE) and protein efficiency ratio (PER) among fish fed control diet, $LCM_{10}, LCM_{20}, LCM_{30}ln, LCM_{ 40}la and LCM_{40}$lan diets (P>0.05), while fishes fed control diet were significantly higher than those fed $LCM_{30}, LCM_{40} and LCM_{40}l diets (P<0.05)$. Positive effects were not shown in WG and SGR with supplementation of amino acids (lysine & arginine) and neutralizatio, while FE and PER from fish fed $LCM_{40}la and LCM_{40}lan diets were significantly higher than those fed LCM_{30}, LCM_{40} and LCM_{30}$l diets (P<0.05). Hence, LCM can replace FM up to 40%, and dietary suppl-ementacon and neutralization of amino acids showed positive effects, when FE and PER were considered in juvenile tilapia diet.

• Journal of Animal Science and Technology
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• v.52 no.1
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• pp.23-28
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• 2010

This study was conducted to evaluate the effects of probiotics supplementation on growth performance, nutrient digestibility, fecal concentrations of Lactobacillus and Escherichia coli, emission of noxious gases from the feces, and circulating concentrations of the blood cells in early-finishing pigs. A total of sixty pigs [(Landrace ${\times}$ Yorkshire) ${\times}$ Duroc] (initial body weight 56.48 ${\pm}$ 1.66 kg) were used for the 28 days feeding trial. Dietary treatments included 1) CON (basal diet), 2) P1 (CON + 0.1% Agariemycetes) and 3) P2 (CON + 0.2% Agariemycetes). There were three dietary treatments with five replicate pens per treatment and four pigs per pen. There was no significant difference in ADG (average dairy gain) among the treatments (P>0.05). The gain/feed ratio was higher in P2 than CON (P<0.05). The P2 showed the highest digestibility of dry matter and energy (P<0.05). No significant difference was observed in the fecal Lactobacillus counts but fecal Escherichia coli population of P2 was lower than that of CON (P<0.05). The ammonia, $H_2S$ and total mercaptan was higher in P1 and P2 than CON (P<0.05). Blood characteristics were not affected by probiotics (P>0.05) supplementation. In conclusion, the results showed that dietary supplementation of probiotics at 0.2% level affected gain/feed ratio, dry matter and energy digestibility; reduced fecal Escherichia coli and emission of fecal noxious gases in finishing pigs.

• Journal of Wetlands Research
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• v.24 no.3
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• pp.204-212
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• 2022

The LID technique began to be applied in Korea after 2009, and LID facilities are installed and operated for rainwater management in business districts such as the Ministry of Environment, the Ministry of Land, Infrastructure and Transport, and LH Corporation, public institutions, commercial land, housing, parks, and schools. However, looking at domestic cases, the application cases and operation periods are insufficient compared to those outside the country, so appropriate design standards and measures for operation and maintenance are insufficient. In particular, LID facilities constructed using LID techniques need to maintain the environment inside LID facilities because hydrological and environmental effects are expressed by material circulation and energy flow. The LID facility is designed with the treatment capacity planned for the water circulation target, and the proper maintenance, vegetation, and soil conditions are periodically identified, and the efficiency is maintained as much as possible. In other words, the soil created in LID is a very important design element because LID facilities are expected to have effects such as water pollution reduction, flood reduction, water resource acquisition, and temperature reduction while increasing water storage and penetration capacity through water circulation construction. In order to maintain and manage the functions of LID facilities accurately, the current state of the facilities and the cycle of replacement and maintenance should be accurately known through various quantitative data such as soil contamination, snow removal effects, and vegetation criteria. This study was conducted to investigate the current status of LID facilities installed in Korea from 2009 to 2020, and analyze soil changes through the continuity and current status of LID facilities applied over the past 10 years after collecting soil samples from the soil layer. Through analysis of Saturn, organic matter, hardness, water contents, pH, electrical conductivity, and salt, some vegetation-type LID facilities more than 5 to 7 years after construction showed results corresponding to the lower grade of landscape design. Facilities below the lower level can be recognized as a point of time when maintenance is necessary in a state that may cause problems in soil permeability and vegetation growth. Accordingly, it was found that LID facilities should be managed through soil replacement and replacement.

• Clean Technology
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• v.29 no.4
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• pp.255-261
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• 2023

Power semiconductors are semiconductors used for power conversion, transformation, distribution, and control. Recently, the global demand for high-voltage power semiconductors is increasing across various industrial fields, and optimization research on high-voltage IGBT components is urgently needed in these industries. For high-voltage IGBT development, setting the resistance value of the wafer and optimizing key unit processes are major variables in the electrical characteristics of the finished chip. Furthermore, the securing process and optimization of the technology to support high breakdown voltage is also important. Etching is a process of transferring the pattern of the mask circuit in the photolithography process to the wafer and removing unnecessary parts at the bottom of the photoresist film. Ion implantation is a process of injecting impurities along with thermal diffusion technology into the wafer substrate during the semiconductor manufacturing process. This process helps achieve a certain conductivity. In this study, dry etching and wet etching were controlled during field ring etching, which is an important process for forming a ring structure that supports the 3.3 kV breakdown voltage of IGBT, in order to analyze four conditions and form a stable body junction depth to secure the breakdown voltage. The field ring ion implantation process was optimized based on the TEG design by dividing it into four conditions. The wet etching 1-step method was advantageous in terms of process and work efficiency, and the ring pattern ion implantation conditions showed a doping concentration of 9.0E13 and an energy of 120 keV. The p-ion implantation conditions were optimized at a doping concentration of 6.5E13 and an energy of 80 keV, and the p+ ion implantation conditions were optimized at a doping concentration of 3.0E15 and an energy of 160 keV.