• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.1-8
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• 2017

The purpose of this study is to suggest the rupture disk design(size) and application at the two phase(gas-liquid) flow by runaway reaction at batch reactor. The definition of runaway reaction is abnormally exothermic reaction by the uncontrolled cooling water or deviated operating condition. As a result, the temperature of reactor is rapidly increasing. The causes of runaway reaction are either self-heating reaction or sleeper reaction. General methods of rupture disk size or safety valve are not suitable in the runaway reaction, because of temperature and pressure increasing rapidly in the reactor and the phases of relieving fluid is 2-phase flow. This study case of the reactor incident, the depressurization system such as safety valve and vent installed, however, the system did not relieved the pressure of reactor suitably. The orifice size of the safety valve were designed too small because the size had not been considered the phenomena and character of reaction. The batch reactor design should be considered by referring to the possibility of runaway reaction proposed in this study and the size of rupture disk design method considering 2-phase flow.

• Tribology and Lubricants
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• v.32 no.6
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• pp.183-188
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• 2016

Engine oil plays an important role in the mechanical lubrication and cooling of a vehicle engine. Recently, engine development has focused on the adoption of gasoline direct injection (GDI) and turbocharging methodology to achieve high-power and high-speed performance. However, oil dilution is a problem for GDI engines. Oil dilution occurs owing to high-pressure fuel injection into the combustion chamber when the engine is cold. The chemical components of engine oil are currently developed to accommodate gasoline fuel; however, bio-alcohol mixtures have become a recent trend in fuel development. Bio-alcohol fuels are alternatives to fossil fuels that can reduce vehicle emissions levels and greenhouse gas pollution. Therefore, the chemical components of engine oil should be improved to accommodate bio-alcohol fuels. This study employs a 2.0 L turbo-gas direct injection (T-GDI) engine in an experiment that dilutes oil with fuel. The experiment utilizes a variety of fuels, including sub-octane gasoline fuel (E0) and a bio-alcohol fuel mixture (Ethanol E3~E7). The results show that the lowest amount of oil dilution occurs when using E3 fuel. Analyzing the diluted engine oil by measuring density and moisture with respect to kinematic viscosity shows that the lowest values of these parameters occur when testing E3 fuel. The reason is confirmed to influence the vapor pressure of the low concentration bio-alcohol-fuel mixture.

• The Korea Journal of Herbology
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• v.31 no.6
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• pp.63-71
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• 2016

Objective : To suggest a scientific evidence of Aconitum carmichaeli Debx. (Aconiti Lateralis Radix Preparata: ALRP) as one of cooling and heating medicines on the regulation of body temperature, we investigated the effects of ALRP water extract on hypothyroidism. Methods : Hypothyroidism was induced by intradermal injection with PTU for 4 weeks in SD rats. ALRP extract or L-thyroxine as a control drug was orally administrated for 2 weeks with PTU injection in rats. The physiological and serological parameters were measured in rats. The histological change of thyroid tissues was observed by H&E staining, and also the expression of thermo-regulating proteins was determined by Western blot in dorsal root ganglia and brain tissues of rats. Results : The administration of ALRP extract in PTU-induced hypothyroidism rats was significantly increased body temperature, but did not changes on body weight, food and water intake. ALRP extract did not effect on the levels of TSH and T4 in the hypothyroidism rats. ALRP extract significantly decreased the levels of GPT, glucose, HDL-cholesterol, LDL-cholesterol, and total cholesterol in the hypothyroidism rats. In histological observation, the enlarged epithelium and atrophic follicles with higher concentration of follicular cells on hypothyroidism were improved by ALRP extract. In addition, ALRP extract increased the expression of TRPV1 and TRPM8 ion channel proteins in hypothyroidism rats. Conclusion : These results indicate that ALRP extract can improve PTU-induced hypothyroidism through regulation of body temperature and lipid accumulation. The action mechanism of ALRP extract is related with body temperature control by thermoregulation with TRP ion channels.

• Korean Journal of Acupuncture
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• v.36 no.3
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• pp.171-180
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• 2019

Objectives : Although the tonification and sedation method such as mountain-burning fire method and heaven-penetrating cooling method, is one of the important techniques that have been claimed to increase the effect of acupuncture, research on this has been sparse. The aim of this study is to provide an understanding of tonification and sedation methods in the "Yeongsochimgugyeong". Methods : We analyzed the similarities and differences by comparing the contents of the tonification and sedation method described in books "Yeongsochimgugyeon" and "Complete Compendium of Acupuncture and Moxibustion" Results : A total of 28 out of the 33 tonification and sedation methods described in "Yeongsochimgugyeon" were compared with those in "Complete Compendium of Acupuncture and Moxibustion". As a result, we found that many of the tonification and sedation methods recorded in "Yeongsochimgugyeon" were based on more detailed and specific clinical cases. Conclusions : The tonification and sedation methods in "Yeongsochimgugyeon" were not only descriptive and consistent in describing that methods, but also contains valuable information for clinical use. In the future, based on this research, we will be able to clinically implement these tonification and sedation methods and quantitatively evaluate them.

• Tribology and Lubricants
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• v.38 no.2
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• pp.41-52
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• 2022

Mineral electrical insulating oil, which is widely used in transformers, exhibits excellent cooling performance and transformer efficiency. However, given that it is composed of petroleum-based components, it is weak in terms of biodegradability. This causes environmental problems in case of leakage and a low flash point, which is a factor that would cause great damage in the event of a fire in a substation. In this context, the use of eco-friendly electric insulating oil composed of bio-based vegetable oil and synthetic ester, which has excellent biodegradability and flame retardancy performance, has recently been expanded to the field of electric power, and various research and development (R&D) studies are in progress. According to different research results, vegetable oil and synthetic ester manufacturing technology, thermal stability, oxidation stability, property change, and quality control, which are characteristics of eco-friendly electrical insulating oils, are major factors affecting the maintenance of insulating oil properties. In addition, power companies have established and operated quality control standards according to the use of eco-friendly electrical insulating oil as they expand the exploitatoin of renewable energy in electricity production. In particular, deterioration and oxidation characteristics were jointly identified in R&D as an important influencing factor according to the content of saturated and unsaturated fatty acids present in vegetable oils and synthetic esters in power transformer applications.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.45.1-45.1
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• 2021

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on aGpc scale while achieving a resolution of 1kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. On the back of a remarkable achievement of this, we have finished to run follow-up simulations which have 2 times larger volume than before and are expected to complementary to some limitations of previous HR simulations both for the study on the large scale features and the expansion history in a distant Universe. For these simulations, we consider the sub-grid physics of radiative heating/cooling, reionization, star formation, SN/AGN feedbacks, chemical evolution and the growth of super-massive blackholes. In order to do this project, we implemented a hybrid MPI-OpenMP version of the RAMSES code, 'RAMSES-OMP', which is specifically designed for modern many-core many thread parallel systems. These simulation successfully reproduce various observation result and provide a large amount of statistical samples of Lyman-alpha emitters and protoclusters which are important to understand the formation and expansion history of early universe. These are invaluable assets for the interpretation of current ΛCDM cosmology and current/upcoming deep surveys of the Universe, such as the world largest narrow band imaging survey, ODIN (One-hundred-square-degree Dark energy camera Imaging in Narrow band).

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.194-199
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• 2016

Presently, for the cement industry, studies that seek to reduce $CO_2$, because of the development of the plastic industry and demand for reduction of energy use, have been actively conducted among them, studies attempting to use Gamma-$C_2S({\gamma}-C_2S)$ to fix $CO_2$ have been actively conducted. The ${\gamma}-C_2S$ compound has an important function in reacting to $CO_2$ and stiffening through carbonatization in the air. The ${\gamma}-C_2S$ compound, reacting to $CO_2$ in the air, generates $CaCO_2$ within the pore structure of cement materials and densifies the pore structure this leads to an improvement of the durability and to the characteristic of resistance against neutralization. Therefore, in this experiment, in order to synthesize ${\gamma}-C_2S$, limestone sludge and waste foundry sands are used these materials are plasticized for 30 or 60 minutes at $1450^{\circ}C$, and are prevented from being cooled in the temperature range of $30{\sim}1000^{\circ}C$ when they are about to be cooled. XRD analysis and XRF analysis are used to determine the effects of this process on ${\gamma}-C_2S$ synthesization, the temperature at which a thing is plasticized, and the conditions for cooling that obtain in the plasticized clinker also, in order to confirm the $CO_2$ capture function, analysis of the major hydration products is conducted through an analysis of carbonatization depth and compressive strength, and through MIP analysis and XRD Rietveld analysis. As a result of these analyses, it is found that when ${\gamma}-C_2S$ was synthesized, the clinker that was plasticized at $1450^{\circ}C$ for one hour demonstrated the highest yield rate the sample with which the ${\gamma}-C_2S$ was mixed generated $CaCO_3$ when it reacted with $CO_2$ therefore, carbonatization depth and porosity were reduced, and the compressive strength was increased.

• Journal of Climate Change Research
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• v.1 no.3
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• pp.189-203
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• 2010

The objective of this study is the estimate of $CO_2$ emissions by the energy consumption of functional technology introduced by classifying energy use in households according to functions as well as energy resources. This study also intends to provide the practical basis data in order to establish specific alternatives for GHG mitigation in residential sector with examining the cause analysis affecting $CO_2$ emission increases from 1995 to 2007. The results of this study show a 6.6% increase in the total $CO_2$ from 60,636 thousand tons in 1995 to 64,611 thousand tons in 2007 by using energy in residential sector. Heating is the greatest $CO_2$ emission sector by use, followed electric appliances, cooking, lighting and cooling. Heating sector shows 56.6% reductions from 71.5% in 1995 and as do cooling and electric home appliances, with a 2.4% increase from 0.6% and a 21.8% increase from 14.2% respectively. To analyze factors resulted in $CO_2$ emissions in residential sector, the relevant indicator change rate from 2005 to 2007 was examined. The results find that population, the number of household, housing areas, family patterns, and family income resulted in the $CO_2$ emissions increase in residential sector from 1995 to 2007. On the other hand, carbon intensity and energy intensity contribute to $CO_2$ reduction in residential sector with -2% and -38.7% respectively because of the energy conversion and the improvement of energy efficiency in electronic appliances. This study can be used as a reference when taken account of the reality and considered the introduction of highly effective measures to increase the possibility of mitigation potential in residential sector hereafter.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.391-396
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• 2016

The absorption efficiency of amine $CO_2$ absorbent (KoSol-5) developed by KEPCO research institute was evaluated using a 0.1 MW test bed. The performance of post-combustion technology to capture two tons of $CO_2$ per day from a slipstream of the flue gas from a 500 MW coal-fired power station was first confirmed in Korea. Also the analysis of the absorbent regeneration energy was conducted to suggest the reliable data for the KoSol-5 absorbent performance. And we tested energy reduction effects by improving the absorption tower inter-cooling system. Overall results showed that the $CO_2$ removal rate met the technical guideline ($CO_2$ removal rate : 90%) suggested by IEA-GHG. Also the regeneration energy of the KoSol-5 showed about $3.05GJ/tonCO_2$ which was about 25% reduction in the regeneration energy compared to that of using the commercial absorbent MEA (Monoethanolamine). Based on current experiments, the KoSol-5 absorbent showed high efficiency for $CO_2$ capture. It is expected that the application of KoSol-5 to commercial scale $CO_2$ capture plants could dramatically reduce $CO_2$ capture costs.

• Journal of the Korean association of regional geographers
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• v.23 no.1
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• pp.151-167
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• 2017

The main objective of this study was to investigate the climatic impact of $PM_{10}$ concentration on the temperature change pattern in Busan Metropolitan City(BMC), Korea during 2001~2015. Mean $PM_{10}$ concentration of BMC has gradually declined over the past 15 years. While the highest $PM_{10}$ concentration was observed in spring followed by winter, summer, and fall on average, the seasonal variations of $PM_{10}$ concentration differed from place to place within the city. Frequency analysis showed that the most frequently observed $PM_{10}$ concentration ranged from $20{\mu}g/m^3$ to $60{\mu}g/m^3$, which accounted for 64.6% of all daily observations. Overall, the west-high and east-low pattern of $PM_{10}$ concentration was relatively strong during the winter when the effect of yellow-dust events on the air quality was weak. Comparative analyses between $PM_{10}$ concentration and monthly temperature slope derived from generalized temperature curves indicated that the decreasing trend of $PM_{10}$ concentration was associated with increases of annual temperature range, and $PM_{10}$ concentration had a negative relationship with the temperature slope of warming months. Overall, $PM_{10}$ concentration had a weak correlation with the annual mean temperature, but it had a significant, positive correlation with the winter season, which had a dominant influence on the annual mean temperature. In terms of energy budget, it has been known that the change in $PM_{10}$ concentration contributes to the warming or cooling effect by affecting the radiative forcing due to the reflection and absorption of radiant energy. The correlation between $PM_{10}$ concentration and temperature changes in the study area was not seasonally and spatially consistent, and its significance was statistically limited partly due to the number of observations and the lack of potential socioeconomic factors relevant to urban air quality.