• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.365-374
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• 2008

Plastics are comparatively new polymeric materials that are manufactured by chemical synthesis, making them different from natural materials such as wood, paper, stone, metal, and glass. Due to a wide range of properties, including processing capabilities and duration, plastics have become rapidly ubiquitous, being used in all industries, and have improved our quality of life. However, it is true that plastics cause environmental contamination problems that have become important social issues, such as environmental hormone leakage due to incineration or reclamation, difficulty in securing reclamation sites, and deadly poisonous dioxin generated by the incomplete incineration of waste plastic materials. To solve these problems, it is urgent to develop and commercialize degradable plastics that can be stably and conveniently used just as general plastics, and that are easily decomposed by sunlight, soil microbes, and heat generated from reclaimed land after use. This review presents recent worldwide trends in the development and marketing of environmentally degradable plastics.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.8
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• pp.1075-1082
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• 2016

Modern livestock production became highly intensive and large scaled to increase production efficiency. This production environment could add stressors affecting the health and growth of animals. Major stressors can include environment (air quality and temperature), nutrition, and infection. These stressors can reduce growth performance and alter immune systems at systemic and local levels including the gastrointestinal tract. Heat stress increases the permeability, oxidative stress, and inflammatory responses in the gut. Nutritional stress from fasting, antinutritional compounds, and toxins induces the leakage and destruction of the tight junction proteins in the gut. Fasting is shown to suppress pro-inflammatory cytokines, whereas deoxynivalenol increases the recruitment of intestinal pro-inflammatory cytokines and the level of lymphocytes in the gut. Pathogenic and viral infections such as Enterotoxigenic E. coli (ETEC) and porcine epidemic diarrhea virus can lead to loosening the intestinal epithelial barrier. On the other hand, supplementation of Lactobacillus or Saccharaomyces reduced infectious stress by ETEC. It was noted that major stressors altered the permeability of intestinal barriers and profiles of genes and proteins of pro-inflammatory cytokines and chemokines in mucosal system in pigs. However, it is not sufficient to fully explain the mechanism of the gut immune system in pigs under stress conditions. Correlation and interaction of gut and systemic immune system under major stressors should be better defined to overcome aforementioned obstacles.

• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.32-37
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• 2005

The purpose of this study is for the sensitivity study f9r a Steam Generator Tube Rupture (SGTR) of the System-integrated Modular Advanced ReacTor for a Pilot (SMART-P) plant. The thermal hydraulic analysis of a SGIR for the Limiting Conditions for Operation (LCO) is performed using TASS/SMR code. The TASS/SMR code can calculate the core power, pressure, flow, temperature and other values of the primary and secondary system for the various initiating conditions. The major concern of this sensitivity study is not the minimum Critical Heat Flux Ratio(CHFR) but the maximum leakage amount from the primary to secondary sides at the steam generator. Therefore the break area causing the maximum accumulated break flow is researched for this reason. In the case of a SGIR for the SMART-p, the total integrated break flow is 11,740kg in the worst case scenario, the minimum CHFR is maintained at Over 1.3 and the hottest fuel rod temperature is below 606"I during the transient. It means that the integrity of the fuel rod is guaranteed. The reactor coolant system and the secondary system pressures are maintained below 18.7MPa, which is system design pressure.

• Journal of the Korean Institute of Gas
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• v.22 no.4
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• pp.1-6
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• 2018

An LNG bunkering system stores LNG in a horizontal IMO's C-Type tank insulated with perlite powder, and $10^{-2}$ Torr vacuum in the annular space between the double walls. Current storage tanks have high heat leakage, evaporating over 2.0% daily. A more efficiently insulated storage tank reducing the evaporation rate is required to develope. This research carried out thermal analysis on a new effective insulation method, i.e. double shield insulation system, that separates high super vacuum in the annular space between two tanks with a perlite vacuum in the back side of outer tank. This highly efficient insulation system obtained an evaporation rate of 0.16% per day under a $10^{-4}$ Torr vacuum. Even if the space loses its vacuum, the new insulation system showed a lower evaporation rate of 5.23% than the present perlite system of 4.9%.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.spc
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• pp.21-36
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• 2020

With respect to spent nuclear fuels, disposal containers and bentonite buffer blocks in deep geological disposal systems are the primary engineered barrier elements that are required to isolate radioactive toxicity for a long period of time and delay the leakage of radio nuclides such that they do not affect human and natural environments. Therefore, the thermal stability of the bentonite buffer and structural integrity of the disposal container are essential factors for maintaining the safety of a deep geological disposal system. The most important requirement in the design of such a system involves ensuring that the temperature of the buffer does not exceed 100℃ because of the decay heat emitted from high-level wastes loaded in the disposal container. In addition, the disposal containers should maintain structural integrity under loads, such as hydraulic pressure, at an underground depth of 500 m and swelling pressure of the bentonite buffer. In this study, we analyzed the thermal stability and structural integrity in a deep geological disposal environment of the improved deep geological disposal systems for domestic light-water and heavy-water reactor types of spent nuclear fuels, which were considered to be subject to direct disposal. The results of the thermal stability and structural integrity assessments indicated that the improved disposal systems for each type of spent nuclear fuel satisfied the temperature limit requirement (< 100℃) of the disposal system, and the disposal containers were observed to maintain their integrity with a safety ratio of 2.0 or higher in the environment of deep disposal.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.464-469
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• 2002

$SrBi_2Nb_2O_9(SBN)$ thin films were grown on Pt/Ti/Si and p-type Si(100) substrates by rf-magnetron co-sputtering method using two ceramic targets, $SrNb_2O_6\; and \;Bi_2O_3$. The structural and electrical characteristics have been investigated to confirm the possibility of the SBN thin films for the applications to destructive and nondestructive read out ferroelectric random access memory(FRAM). For the optimum growth condition X-ray diffraction patterns showed that SBN films had well crystallized Bi-layered perovskite structure after $700^{\circ}C$ heat-treatment in furnace. From this specimen we got remnant polarization $(2P_r)$ of about 6 uC/$\textrm{cm}^2$ and coercive voltage $(V_c)$ of about 1.5 V at an applied voltage of 5 V. The leakage current density was $7.6{\times}10^{-7}$/A/$\textrm{cm}^2$ at an applied voltage of 5V. And for the NDRO-FRAM application, properties of SBN films on Si substrate has been investigated. From transmission electron microscopy (TEM) analysis, we found the furnace treated sample had a native oxide about 2 times thicker than the RTA treated sample and this thick native oxide layer had a bad effect on C-V characteristics of SBN/Si thin film. After $650^{\circ}C$ RTA process, we got the improved memory window of 1.3 V at an applied voltage of 5 V.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.184-189
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• 2002

The electrical and optical properties of $(Pb_{0.91}La_{0.09})(Zr_{0.65}Ti_{0.35})O_3$(PLZT) thin films by MOCVD using ultrasonic spraying were investigated. To compensate the Pb loss by evaporation, 5 and 10 wt% of excess Pb was added to 0.2 M precursor. After deposition of films on ITO-coated glasses in oxygen atmosphere for 30 min, films were heated by in-situ RTA (rapid thermal annealing) method. When the films were heat treated at $600^{\circ}C$, perovskite single phase was obtained. The optical property of the film with 10 wt% excess Pb was excellent showing about 84 % of transmittance near 520 nm. The dielectric constant of the film was about 308 and the leakage current of the film was lower than the Pb excess 0, 5 wt% PLZT thin films.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.76-80
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• 2010

Oil hydraulic piston pumps are being extensively used around the world, because of their simple design, light weight, effective cost, etc. An oil hydraulic pump is likely to have the serious problems of high leakage, friction, and low energy efficiency after a long period of use. In an oil hydraulic piston pump, the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this study, the wear property of the SACM645 material with DLC coating used for a hydraulic piston pump was determined by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, five different types of specimens were prepared. The maximum tensile strengths of the QT and QT Nitration specimens had similar values of about 800 MPa, but the strains indicated a big difference. In a wear test, the wear characteristic of the DLC coating specimen was shown to be excellent. The QT, QT + IH, QT + Nitration, and matirx specimen showed similar wear characteristics. In the case of a dry condition without oil, the DLC coating specimen had good wear resistance, with no wear shown.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.257-263
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• 2005

Short-circuit rotor windings on a generator causes unstable oscillation of unbalance of flux, asymmetrical heat. In order to prevent serious accidents of short-circuit rotor windings, it is important to study the shorted-turn diagnosis method for rotor windings of the generator. To improve the defects of the diagnosis with sensors, the new sensorless method for rotor shorted-turn diagnosis is proposed, which is to measure the electrical values of the voltage and current at the generator and then to detect if the shorted-turned phenomena would occurred. For the feasibility of the suggested method the theoretical results are shown in the aspects of the air-gap flux density, the flux leakage, the generated output voltage and the shorted field current through the digital simulation. Also the possibility of decision for the suggested sensorless method could be shown in this paper.

• Journal of Hydrogen and New Energy
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• v.26 no.2
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• pp.114-119
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• 2015

Nowdays, fossil fuels have been used as an important resource in development of industry. But it is limited and caused climate change such as pollution and global warming. So nuclear fusion research is being issued with tritium to develop eco-friendly and sustainable energy. Republic of Korea is in charge of Storage and Delivery System (SDS) in the International Thermonuclear Experimental Reactor (ITER), weld present in the SDS bottles are easily exposed to the hydrogen embrittlement of special characteristics of the hydrogen in hydrogen atmosphere, When the hydrogen embrittlement is rapidly progresses, the cracking is generated in the weld zone. Due to this cracking, the risk of leakage of tritium into the atmosphere occurs. In this study, hydrogen heat treatment was processed through the Pressure-Composition-Temperature (PCT) device according to the time variation. Also mechanical properties such as rupture strength test, three point bend test and hardness test in accordance with the respective time have been conducted and the fracture was observed by scanning electron microscopy(SEM) after the mechanical properties evaluation.