• Nuclear Engineering and Technology
• /
• v.47 no.3
• /
• pp.227-239
• /
• 2015

The thermal, mechanical, and neutronic performance of the metal alloy fast reactor fuel design complements the safety advantages of the liquid metal cooling and the pool-type primary system. Together, these features provide large safety margins in both normal operating modes and for a wide range of postulated accidents. In particular, they maximize the measures of safety associated with inherent reactor response to unprotected, doublefault accidents, and to minimize risk to the public and plant investment. High thermal conductivity and high gap conductance play the most significant role in safety advantages of the metallic fuel, resulting in a flatter radial temperature profile within the pin and much lower normal operation and transient temperatures in comparison to oxide fuel. Despite the big difference in melting point, both oxide and metal fuels have a relatively similar margin to melting during postulated accidents. When the metal fuel cladding fails, it typically occurs below the coolant boiling point and the damaged fuel pins remain coolable. Metal fuel is compatible with sodium coolant, eliminating the potential of energetic fuel-coolant reactions and flow blockages. All these, and the low retained heat leading to a longer grace period for operator action, are significant contributing factors to the inherently benign response of metallic fuel to postulated accidents. This paper summarizes the past analytical and experimental results obtained in past sodium-cooled fast reactor safety programs in the United States, and presents an overview of fuel safety performance as observed in laboratory and in-pile tests.

• Journal of Pharmaceutical Investigation
• /
• v.37 no.1
• /
• pp.51-55
• /
• 2007

Solid lipid nanoparticles (SLNs) have been regarded to behave similar to the vegetable oil emulsions because emulsions of lipid melts are formed before lipid droplets being solidified to turn into SLNs. Compared to lipid emulsion, however, it has been more difficult to obtain stable SLNs and needs more extensive considerations on stabilizer and manufacturing process. In the present study, we tried to prepare phosphatidylcholine-based trymyristin (TM) SLNs using high pressure homogenization method and optimize the manufacturing variables such as homogenization pressure, number of homogenization cycles, cooling temperature, co-stabilizer and freeze-drying with cryoprotectants. Nano-sized TM particles could be Prepared using egg Phosphatidylcholine and pegylated phospholipids ($PEG_{2000}$PE) as stabilizers. Based on the optimization study, the dispersion was manufactured by homogenization under the pressure of 100 MPa for more than 5 cycles, and solidifying the intermediately formed lipid melt droplets by dipping in liquid nitrogen followed by thawing at room temperature. In addition, TM SLNs could be freeze-dried and then redispersed easily without significant particle size changes after freeze drying with 10% and 12.5% sucrose or trehalose. The TM SLNs established in this study can be used as delivery system for drugs and cosmetics.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.3 no.2
• /
• pp.136-140
• /
• 2002

The investment casting process is used frequently to manufacture precise and complex shape metal parts. The previous wax pattern manufacturing process takes long time and high costs because the process is performed by hands. In order to improve the wax manufacturing process, a new process is developed to manufacture the wax pattern by using a rapid prototyping system. A CastForm pattern is made by a Selective laser Sintering type RP with CastForm powder. The CastForm pattern is dipped in the melted wax liquid, and the melted wax penetrates into the pores of the CastForm pattern. Wax pattern is obtained after cooling the CastForm pattern slowly. A stainless steel part has been manufactured by the suggested process. By obtaining the suggested process the manufacturing time and costs are reduced largely and the accuracy is improved.

• Journal of the Society of Disaster Information
• /
• v.16 no.4
• /
• pp.701-711
• /
• 2020

Purpose: In this study, the risk of flammability of a liquid mixture was experimentally confirmed because the purpose of this study was to confirm the increase or decrease of the flammability risk in a mixture of two substances (combustible+combustible) and to present the risk of the mixture. Method: Flash point test method and result processing were tested based on KS M 2010-2008, a tag sealing test method used as a flash point test method for crude oil and petroleum products. The manufacturer of the equipment used in this experiment was Japan's TANAKA. The flash point was measured with a test equipment that satisfies the test standards of KS M 2010 with equipment produced by the company, and LP gas was used as the ignition source and water as the cooling water. In addition, when measuring the flash point, the temperature of the cooling water was tested using cooling water of about 2℃. Results: First of all, in the case of flammable + combustible mixtures, there was little change in flash point if the flash point difference between the two substances was not large, and if the flash point difference between the two substances was low, the flash point tended to increase as the number of substances with high flash point increased. However, in the case of toluene and methanol, the flash point of the mixture was lower than that of the material with a lower flash point. Also, in the case of a paint thinner, it was not easy to predict the flash point of the material because it was composed of a mixture, but as a result of experimental measurement, it was measured between -24℃ and 7℃. Conclusion: The results of this study are to determine the risk of mixtures through experimental studies on flammable mixtures for the purpose of securing the effectiveness of the details of the criteria for determining dangerous goods in the existing dangerous goods safety management method and securing the reliability and reproducibility of the determination of dangerous goods Criteria have been presented, and reference data on experimental criteria for flammable liquids that are regulated in firefighting sites can be provided. In addition, if this study accumulates know-how on differences in test methods, it is expected that it can be used as a basis for research on risk assessment of dangerous goods and as a basis for research on dangerous goods determination.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.4
• /
• pp.459-469
• /
• 2016

Gas hydrate desalination process is based on a liquid to solid (Gas Hydrate, GH) phase change followed by a physical process to separate the GH from the remaining salty water. The GH based desalination process show 60.5-90% of salt rejection, post treatment like reverse osmosis (RO) process is needed to finally meet the product water quality. In this study, the energy consumption of the GH and RO hybrid system was investigated. The energy consumption of the GH process is based on the cooling and heating of seawater and the heat of GH formation reaction while RO energy consumption is calculated using the product of pressure and flow rate of high pressure pumps used in the process. The relation between minimum energy consumption of RO process and RO recovery depending on GH salt rejection, and (2) energy consumption of electric based GH process can be calculated from the simulation. As a result, energy consumption of GH-RO hybrid system and conventional seawater RO process (with/without enregy recovery device) is compared. Since the energy consumption of GH process is too high, other solution used seawater heat and heat exchanger instead of electric energy is suggested.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.40 no.4
• /
• pp.164-170
• /
• 2017

The CNC machine tool field is showing a growing trend with the recent rapid development of manufacturing industries such as semiconductors, automobiles, medical devices, various inspection and test equipment, mechanical metal processing equipment, aircraft, shipbuilding and electronic equipment. However, small and medium-sized machining companies that use CNC machine tools are experiencing difficulties in increasingly intense competition. Especially, small companies which are receiving orders from 3rd or 4th venders are very difficult in business management. In recent years, company S experienced difficulty to make product quality and delivery time due to the ignorance of the processing method when manufacturing cooling plate jig made of SUS304 material used for cell phone liquid crystal glass processing. In order to solve these problems, we redesigned the process according to the size of our company and tried to manage all processes with quantified data. In the meantime, we have found that there is a need to improve the cutter process, which accounts for most of the machining process. Therefore, we have investigated the correlation between RPM and FEED of three cutters that have been used in the past. As a result, we found that it is the most urgent problem to solve the roughing process during the cutter operation which occupies more than 70% of the total machining. In order to shorten the machining time and improve the quality in machining of SUS304 cooling plate jig, we select the main factors such as price, tool life, maintenance cost, productivity, quality, RPM, and FEED and use AHP to find the most suitable milling cutter. We also tried to solve the problem of delivery, quality and production capacity which was a big problem of S company through experiment operation with selected cutter tool. As a result, the following conclusions were drawn. First, the most efficient of the three cutters currently available in the machining center has proven to be an M-cutter. Second, although one additional facility was required, it was possible to produce the existing facilities without additional investment by supplementing the lack of production capacity due to productivity improvement. Third, the Company's difficulties in delivery and capacity shortfalls have been resolved. Fourth, annual sales increased by KRW 109 million and profits increased by KRW 32 million annually. Fifth, it can confirm the usefulness of AHP method in corporate decision making and it can be utilized in various facility investment and process improvement in the future.

• Herbal Formula Science
• /
• v.25 no.4
• /
• pp.553-574
• /
• 2017

The purpose of this study is to find out effects of prescriptions according to the formula, manipulation of Rhei Rhizoma, configuration. The following results were reached through investigations on the prescriptions using Rhei Rhizoma as a main component. Objectives : Analysis of prescriptions According to the formula : Liquid Extract Prescriptions were used widely on three parts to treat fever and damp heat in the interior organs. Powder Prescriptions were taken with hot water, thin porridge, tea etc. to treat damp heat, congestion of phlegm, acute episodes. Liquid Mixed Pill treat congestion of QI, damp heat, phlegm. Honey Mixed Pill treat accumulated fever, distension, acute excessive fever. Paste Pill treat blood stagnation, excessive toxic-fever, epidemic diseases. External Application treat inflammation by injury, swelling due to severe fever by internal damage. Methods : Analysis of prescriptions According to the manipulation of Rhei Rhizoma : Prescriptions including Liquor processed Rhei Rhizoma treat excessive toxic-fever, congestion of phlegm, blocking orifices on the upper side. Steamed Rhei Rhizoma strengthen effects of making evacuate and cooling of heat. Processed Rhei Rhizoma with vinegar strengthen effects of removing blood stagnation by activating blood movement, releasing gathering. Results : Analysis of prescriptions According to the Composition of Rhei Rhizoma : 41% of the total prescriptions were on the area of less than 20%. In case of lower groups show increased frequency of combination with Pharbitidis Semen, Persicae Semen, Scutellariae Radix and manipulation of baking, steaming, roasting. In case of higher groups show increased frequency of treating excess syndrome, critical illness, acute severe illness, and using proccesed Rhei Rhizoma with vinegar. Treatment of damp heat on the liver and gallbladder, disorder of the spleen and stomach is done mostly by prescriptions on the area of less than 30%. Conclusions : Rhei Rhizoma-Coptidis Rhizoma pair treat damp heat, heat toxins in blood, and Constipation caused by excessive heat. Rhei Rhizoma-Glycyrrhizae Radix pair relieve effects of Rhei Rhizoma passing blocked feces, removing the poison, activating blood movement, releasing gathering with the effects of Glycyrrhizae Radix relaxing tension by harmonizing Middle. Rhei Rhizoma-Magnoliae Cortex pair are used to treat damp heat in middle area, excessive heat in the stomach and intestine. Rhei Rhizoma-Pharbitidis Semen pair act on both blood system and QI system treating edema, damp, stagnation, heat toxins, feces. Rhei Rhizoma-Persicae Semen pair treat blood stagnation with fever on blood system.

• Korean Chemical Engineering Research
• /
• v.51 no.5
• /
• pp.587-590
• /
• 2013

Solid-liquid equilibria for mixtures composed of n-vinyl-2-pyrrolidone (NVP) and 2-pyrrolidone were measured as a basic study for the melt crystallization process to remove 2-pyrrolidone as impurity included in NVP. A differential scanning calorimeter (DSC) and a crystallizer were used and the experimental results obtained from two methods were similar. The mixture showed a eutectic system which has a single composition at the minimum melting temperature. Calculation results from simple thermodynamic equations were found in general agreements with present data. To determine the growth rate of NVP crystal which is important for the design of crystallization process, thicknesses of the crystal were measured with the time using a layer melt crystallizer. The growth rates increased as cooling temperatures decreased. Heat transfer coefficient correlated from present data was found to successfully describe the crystal growth behavior.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.9 no.3
• /
• pp.25-37
• /
• 2005

For pump-fed rocket propulsion system, the temperature of LOX to be supplied to turbopump inlet should be satisfied with pump inlet temperature requirement during all operating stages, as excessive temperatures can result in cavitation due to reduction in NPSH, thus either damaging the pump or adversely affecting pump performance rise. So exact estimation of LOX temperature rise is absolutely needed for developing reliable propulsion system. This paper presents systematic analysis scheme for estimating inner process of cryogenic propellant tank which is needed for LOX temperature rise. And this paper presents LOX temperature rise and thermal stratification for all rocket operating stages including cooling, filling, waiting, pre-pressurization and firing, with the application of buoyancy driven boundary layer theory.

• Journal of the Korean Ceramic Society
• /
• v.32 no.12
• /
• pp.1323-1330
• /
• 1995

The effects of various additives on the microstructures of sintered ZnO varistors were examined. Bi2O3, Sb2O3 and Cr2O3 were added to ZnO step by step to identify the effect of each component. The specimens were prepared by sintering at 110$0^{\circ}C$ and 120$0^{\circ}C$ in ambient atmosphere. In ZnO-Bi2O3-Sb2O3 ternary system, decrease of averge grain size due to antimony oxide addition depends on sintering temperature as well as Bi2O3 content. When Sb2O3 was partly or completely replaced by Cr2O3, grain size was further reduced. A significant amount of pyrochlore phase which was not transformed to spinel and Bi2O3-rich liquid phase seemed to remain during sintering at 110$0^{\circ}C$. Unlike ZnO-Bi2O3-Sb2O3 system, the $\alpha$-spinel phase containing significant amount of Cr did not transform to pyrochlore during furnace cooling. Fine spinel particles around 1${\mu}{\textrm}{m}$ size were ovserved within ZnO grains and grain boundaries, which were believed to be responsible for grain-growth inhibition in ZnO-Bi2O3-Sb2O3.