• 에너지공학
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• 제7권2호
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• pp.187-193
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• 1998

The turbulent heat transfer to low Prandtl number fluid flow through rod bundles is analyzed using k-$\varepsilon$ two-equation model. For the prediction of the turbulent flow field, an anisotropic eddy viscosity model is used. In the analysis of the temperature field, the effects of various parameters such as geometry, Reynolds and Prandtl numbers are considered. The calculation in made for Prandtl numbers from 0.001 to 0.1 in order to analyze the heat transfer to low Prandtl number fluid such as liquid metals. The numerical results show that for small P/D (Pitch/Diameter) geometries low Prandtl number makes severe changes of the rod surface temperature.

• Journal of Radiation Protection and Research
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• 제45권1호
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• pp.11-15
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• 2020

Background: There have been various studies to investigate the mechanisms of DNA damage from low-energy electrons. To understand the mechanism of these strand breaks, it is necessary to investigate the dissociation mechanism of the DNA constituents, that is, bases, sugars, and phosphates. Materials and Methods: We studied the dissociation of thymine base upon interaction with low-energy electrons. For this experiment, thymine powder was pressed onto the indium base and irradiated by 5 eV electrons. Results and Discussion: Non-irradiated and irradiated thymine samples were compared and analyzed using the X-ray photoelectron spectroscopic technique to analyze the dissociation patterns of the molecular bonds after low-energy electron irradiation of thymine. Conclusion: With 5 eV electron irradiation, C-C and N-C = O bonds are the primary dissociations that occur in thymine molecules.

• 한국전기전자재료학회논문지
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• 제16권3호
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• pp.175-180
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• 2003

As the integrated circuit device shrinks to the deep submicron regime, the ion implantation process with high ion dose has been attracted beyond the conventional ion implantation technology. In particular, for the case of boron ion implantation with low energy and high dose, the stabilization and throughput of semiconductor chip manufacturing are decreasing because of trouble due to the machine conditions and beam turning of ion implanter system. In this paper, we focused to the improved characteristics of processing conditions of ion implantation equipment through the modified deceleration mode. Thus, our modified recipe with low energy and high ion dose can be directly apply in the semiconductor manufacturing process without any degradation of stability and throughput.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.612-615
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• 2005

Low cycle fatigue tests are performed on the Incollel 617 that be used fur a hot gas casing. The relation between strain energy density and numbers of cycles to failure is examined in order to predict the low cycle fatigue life of Inconel 617. The life predicted by the strain energy method is found to coincide with experimental data and results obtained from the Coffin-Mansun method. Also the cyclic behavior of Inconel 617 is characterized by cyclic hardening with increasing number of cycle at room temperature.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1637-1642
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• 2009

This study evaluates the energy performance of super high-rise residential buildings with e-QUEST simulation and calculates the annual cooling and heating load. The result of this study have concluded that the most influential factor is the characteristics of the window and also suggest the most efficient window system from the result of calculation of different glasses' cooling and heating load. The result of this study shows that The most efficient method to enhance the energy performance is to use low reflective 3 pairs Low-E glass and Low-E coating(inside of outer glass) pair glass.

• 한국진공학회지
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• 제7권s1호
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• pp.37-43
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• 1998

The mechanism of interaction between low energy ions and biological organisms has been paid much attention recently. In order to clarify the microstructural response to low energy ion irradiation embryonic cells of Paeonia rockii L. implanted by $Fe^{1+}$ ions with the energy of 80KeV were investigated by Optical Microscopy (OM), Scanning electron Microscopy(SEM) and Transmission Electron Microscopy(TEM). At the dose of 1$\times$1015 ions/$\textrm{cm}^2$, apparent cellular damage was observed in the outer several layers of the radicle. The shape of the cells was obviously deformed from regular polygon to irregular. The cell walls became obscure. SEM micrographs showed that the surface of the radicle was etched severely. It was observed by TEM that nucleus of the implanted cell was elongated and tended to fracture. Nuclear envelope lost its integrity. The implanted $Fe^{1+}$ ions were detected by Energy Dispersive Spectroscopy (EDS). These observations showed that low energy ions could damage to the plant organisms with the thickness of about 30~50$\mu\textrm{m}$. The possible reasons for radiation damage in the biological organisms were discussed.

• 청정기술
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• 제22권4호
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• pp.299-307
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• 2016

These days, coal is one of the most important energy resources used for transportation, industry, and electricity. There are two types of coal: high-rank and low-rank. Low-rank coal has a low calorific value and contains large amounts of useless moisture. The quality of low-rank coal can be increased by simple drying technology and it needs to be stabilized by hydrocarbons (e.g. palm acid oil, PAO) to prevent spontaneous combustion and moisture re-adsorption. Spontaneous combustion becomes a major problem during coal mining, storage, and transportation. It can involve the loss of life, property, and economic value; reduce the quality of the coal; and increase greenhouse gas emissions. Besides spontaneous combustion, moisture re-adsorption also leads to a decrease in quality of the coal due to its lower heating value. In this work, PAO was used for additive to stabilize the upgraded coal. The objectives of the experiments were to determine the stabilization characteristic of coal by analyzing the behavior of upgraded coal by drying and PAO addition regarding crossing-point temperature of coal, the moisture behavior of briquette coal, and thermal decomposition behavior of coal.

• 대한지역사회영양학회지
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• 제17권2호
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• pp.226-242
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• 2012

Consumption of foods with high energy and low nutrient values has been linked to various health issues including obesity and chronic diseases. This study investigated the high-energy/low-nutrient food consumption status and its relationship with obesity status and intake of energy and nutrients, using the Korea National Health and Nutrition Examination Survey (KNHANES) and the Korea Youth Risk Behavior Web-based Survey (KYRBWS). The prevalence of overweight and obesity among 2-18 year-olds was 8.4% and 10.8% in 2008 and 8.5% and 9.0% in 2009, respectively, in KNHANES. The prevalence of obesity among 12-18 year-olds was 13.9% in 2008 and 11.4% in 2009 in KNHANES, while it was 8.1% in 2008 and 8.2% in 2009 in KYRBWS. Consumption patterns of high-energy/low-nutrient foods were diverse depending on the particular food type. High-energy/low-nutrient foods such as cookies were most often consumed more frequently (2~3 times per week), but fast food type foods were generally consumed less frequently (once per week or less). No significant relationships between highenergy/ low-nutrient food consumption and level of energy and nutrient intakes were found in either datasets. Adolescents who were not obese more frequently consumed ramen (p < 0.001), cookies (p < 0.001) and fast food (p < 0.001) than those who were obese in KYRBWS, however, such relationships were not found in KNHANES. This direction of the relationship could be probably attributed to the cross-sectional nature of the datasets. This study was limited by the cross-sectional nature of the data, therefore, further longitudinal research using various study techniques would be necessary to understand the effects of high-energy/low-nutrient foods on child obesity.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.244.1-244.1
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• 2010

Bio energy development by using Low Calorific Gas Turbine(LCGT) has been developed for New & Renewable energy source for next generation power system, low fuel and operating cost method by using the renewable energy source in landfill gas (LFG), Food Waste, water waste and Livestock biogas. Low calorific fuel purification by pretreatment system and carbon dioxide fixation by green house system are very important design target for evaluate optimum applications for bio energy. Main problems and accidents of Low Calorific Gas Turbine system was derived from bio fuel condition such as hydro sulfide concentration, siloxane level, moisture concentration and so on. Even if the quality of the bio fuel is not better than natural gas, LCGT system has the various fuel range and environmental friendly power system. The mechanical characterisitics of LCGT system is a high total efficiency (>70%), wide range of output power (30kW - 30MW class) and very clean emmission from power system (low NOx). Also, we can use co-generation system. A green house designed for four different carbon dioxide concentration from ambient air to 2000 ppm by utilizing the exhaust gas and hot water from LCGT system. We look forward to contribute the policy for Renewable Portfolio Standards(RPS) by using LCGT power system.

• International Journal of Fluid Machinery and Systems
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• 제6권3호
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• pp.160-169
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• 2013

Two-stage turbocharging is an important way to raise engine power density, to realize energy saving and emission reducing. At present, turbine matching of two-stage turbocharger is based on MAP of turbine. The matching method does not take the effect of turbines' interaction into consideration, assuming that flow at high pressure turbine outlet and low pressure turbine inlet is uniform. Actually, there is swirl flow at outlet of high pressure turbine, and the swirl flow will influence performance of low pressure turbine which influencing performance of engine further. Three-dimension models of turbines with two-stage turbocharger were built in this paper. Based on the turbine models, mechanism of swirl flow at high pressure turbine outlet influencing low pressure turbine performance was studied and a two-stage radial counter-rotation turbine system was raised. Mechanisms of the influence of counter-rotation turbine system acting on low-pressure turbine were studied using simulation method. The research result proved that in condition of small turbine flow rate corresponding to engine low-speed working condition, counter-rotation turbine system can effectively decrease the influence of swirl flow at high pressure turbine outlet imposing on low pressure turbine and increases efficiency of the low-pressure turbine, furthermore increases the low-speed performance of the engine.