• 대한기계학회논문집B
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• 제33권5호
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• pp.365-372
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• 2009

The influence of combustor pressure on the local reaction characteristics of $CH_4$/air flames was investigated by measurements of local chemiluminescence intensity. Induced flow flames are often applied to the industrial boiler systems and incinerator in order to improve heat transfer and prevent exhaust gas leakage. In order to investigate combustion characteristics in the induced flow pattern, the combustor pressure index($P^*$) was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio in the present combustion system, where $P^*$ is defined as the ratio of absolute pressure to atmospheric one. Relationship between local reaction intensity and pressure index have been investigated by simultaneous $CH^*$, $C^*_2$ and $OH^*$ intensity measurements. It could be observed that flame length became longer with decreasing $P^*$ from $CH^*$ chemiluminescence intensity of axial direction. The mean value of $C^*_2$ and $CH^*$ chemiluminescence intensities, which indicates reaction intensity in the $CH_4$/air flames, decreased with decreasing pressure index for ${\Phi}{\leq}1$, but increased with decreasing pressure index for ${\Phi}$>1. $C^*_2/CH^*$ intensity ratio, which can be a good marker to demonstrate local equivalence ratio, was almost same for ${\Phi}{\leq}1$ regardless of pressure index change, while they showed high level for lower pressure index for ${\Phi}$>1 conditions.

• 한국연소학회지
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• 제16권3호
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• pp.33-40
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• 2011

Combustion experiments were conducted at three different fuels ($CH_4$, $C_2H_4$ and $C_3H_8$) to investigate the effects of combustor pressure (30 ~ -30 kPa) on combustion charateristics and reaction zone structure. Regardless of the fuels, emission index of CO (EICO) increased with decreasing combustor pressure, and EICO of $C_2H_4$ was mostly affected by changing combustor pressure at subatmospheric pressure. In order to observe reaction zone, $OH^*$, $CH^*$ and ${C_2}^*$ chemiluminescence intensity were measured. The sequence of the chemiluminescence intensity peak position was affected by chemical characteristics of fuels rather than changing combustor pressure. The emission zone thickness of $C_2H_4$ and $C_3H_8$, defined by the full width at half maximum (FWHM) of $CH^*$ intensity profile, were increased with decreasing combustor pressure. however, the thickness of $C_2H_4$ exhibited the opposite tendency due to the characteristics of the fuel as the bond structure.

• 도시과학
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• 제9권2호
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• pp.45-50
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• 2020

The formation characteristics of calcium carbonates are closely related to the durability and mechanical properties of cement-based materials. In this regard, a deep understanding of the reaction pathway of calcium carbonates is critical. Recently, non-classical nucleation theory was summarized and it was presumed that prenucleation clusters are present. The formation of the prenucleation cluster at undersaturated condition (≈ 0.1 ml) in the present study was investigated via electrical characteristics of an electrolytic solution. Calcium chloride dihydrate (CaCl2·2H2O) and sodium carbonate (Na2CO3) were used as starting materials to supply calcium and carbonate sources, respectively. Furthermore, the reaction pathway of calcium carbonates was investigated by time-resolved polarization and depolarization characteristics of the electrolytic solution. The time-resolved polarization and depolarization tests were conducted by switching polarity with an interval of 20 seconds for 1 hr and by measuring the variation of electrical resistance. It can be inferred from the results obtained in the present study that the reactive constituent for the formation of calcium carbonates was mostly consumed in the period possibly associated with the prenucleation and the reaction pathways may be governed by the monomer-addition mechanism.

• 한국실내디자인학회논문집
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• 제20권6호
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• pp.350-358
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• 2011

In contemporary architecture, Environment is not just a non-objective space. It is an experimental space where physical space and the principal result of interaction and order have been granted in symbolic, introverted space. Therefore, Yokohama International Port Terminal characteristics that appear in the architectural space, the nature of human desires and reveal the value of user-centered criteria to classify the type of response characteristics of the affordance are as follows; First, the experience response in the affordance reaction is when users reaction is multiple in theenvironment. Second, the evolution of organic reactions in a public space system is that it shows the spatial characteristics of the functional relationships. Third, the organic of space that can be seen through cultural practice in the inside and outside of the space could be explained as a perceptual response. It can be an opportunity to analyzed and develop in a various forms of space in environmental design if we understands the spatial characteristics of FOA's Yokohama International Port Terminal and applied end user spatial reaction analysis that shows an affordance relationship study.

• 한국연소학회지
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• 제15권4호
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• pp.65-73
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• 2010

In order to provide fundamental information for developing reaction model in the practical blended coal power plants, effects of particle size and blending ratio on combustion characteristics and thermal reaction in co-firing with bituminous and sub-bituminous coals were experimentally investigated using a TGA and a laboratory-scale burner. Characteristic parameters including ignition, burnout temperature and activation energy were determined from TG and DTG combustion profiles. Distributions of flame length and mean particle temperature were investigated from the visualization of flames in slit-burner system. As coal particle size decreased and volatile matter content increased, characteristic temperatures and activation energy decreased. The ignition/burnout characteristics and activation energy are linearly influenced by a variation in particle size and blending ratio. These results indicated that the control of the coal blending ratio can improve the combustion efficiency for sub-bituminous coals and the ignition characteristics for bituminous coals.

• 한국동물위생학회지
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• 제34권3호
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• pp.201-208
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• 2011

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a pathogen of a variety of infections in horse. We studied biochemical and molecular characteristics of S. zooepidemicus isolated from the genital tract of Thoroughbred mares in Korea. Seventy-nine isolates were identified as S. zooepidemicus by biochemical and PCR method from 374 horses. The biochemical characteristics of S. zooepidemicus isolates were positive reaction of lactose and sorbitol. However, S. zooepidemicus isoltes were negative reaction of inulin, mannitol, raffinose, trehalose, aesculin hydrolysis, growth in 6.5% NaCl and variable reaction of maltose. Epidemiological investigations of S. zooepidemicus isolates were performed by fragment analysis of SzP (S. zooepidemicus protective protein) gene, CNE (collagen binding protein) gene and ISR (16s rRNA intergenic spacer region) gene using ABI Prism $3,130{\times}1$ Genetic Analyzer System. All isolates were shown single amplification size of 906 bp in CNE gene, but SzP and ISR gene were shown variable patterns of fragment size. The characteristics of S. zooepidemicus investigated in this study will be very useful for the prevention of infection and the studies of epidemiologic characteristics of S. zooepidemicus, causing the severe economic losses due to reproductive failures.

• 한국운동역학회지
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• 제25권4호
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• pp.393-399
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• 2015

Objective : This study was conducted with an aim to use it as basic data for developing assistive devices, such as insoles that can suppress the progress of degenerative diseases and strategies, to improve early degenerative diseases by assessing walking characteristics of farm workers who were classified as KL-grade in the perspective of motor mechanics. Method : 38 male and female adults who complained of knee joint pain for more than six months were selected, and they were classified according to KL-grade. KL-grade was assessed by an orthopaedic specialist and an occupational environment health specialist. Filming equipment (FX-1, CASIO, Japan) and a ground reaction force system (AMTI OR6, AMTI, USA) were used to identify ground reaction force characteristics, and WOMAC was used for a pain rating scale. Results : There was a difference between the right and left side (axis-X) according to KL-grade, and when the grade was higher, the internal ground reaction force was also higher. Changes in COP were not affected by KL-grade of the knee joint, but it tended to increase as the grade increased. There were differences in the time required for limb support while walking according to the grades, and when the grade was higher, walking was more inefficient with long braking force and short propulsion forces. Also, pain rating scale, the right and left side, and COP changes while in support phase were related. Conclusion : There was a partial, statically significant difference in KL-grade and ground reaction force occurring during the support phase, and there were differences in ground reaction forces according to the grades of degenerative arthritis in the knee joint, indicating that this study is worthy as basic data for future studies.

• 한국정밀공학회지
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• 제19권7호
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• pp.106-115
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• 2002

Growth characteristics of micro carbon structures fabricated by laser-assisted chemical vapor deposition are studied. Argon ion laser and ethylene were used as the energy source and reaction gas, respectively, to grow micro carbon rod through pyrolytic decomposition of the reaction gas. Experiments were performed at various conditions to investigate the influence of process parameters on growth characteristics such as the diameter or growth rate of the micro carbon rod with respect to reaction gas pressure and incident laser power. Reaction gas pressure in experiments ranges from 200 to 600Torr and the incident laser power from 0.3 to 3.8W. For these conditions, the diameter of the rod increases linearly with respect to the laser power but is almost independent of the reaction gas pressure. Growth rate of the rod changes little with gas pressure when the laser power remains below IW. For a constant reaction gas pressure, the growth rate increase with Increasing laser power, but the rate of increase decreases gradually, implying that the chemical vapor deposition condition changes from a kinetically-limited regime to a mass-transport-limited regime. When the carbon rod was grown at near threshold laser power, a very smooth surface is obtained on the rod. By continuously moving the focusing lens in the direction of growth, a micro carbon rod with a diameter of 287${\mu}{\textrm}{m}$ and aspect ratio of 100 was fabricated..

• 한국주조공학회지
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• 제5권4호
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• pp.271-282
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• 1985

In order to investigate the mold reaction characteristics of Mn steel and Cr steel castings individually, the mold reaction products were examined by scanning electron microscopy, electron prove microanalyzer and X-ray diffractometer. From this experiment, the results were summarized as follows: 1) The mold reaction depth increased with increase of Mn content, while it decreased with increase of Cr content. 2) Mold reaction depth decreased with Mn content at $1200^{\circ}C$. 3) Mn, among the reaction products, forms a low fusion silicate, Mn $O.SiO_2$ while Cr forms a stable oxide, $CrO_3$ which hindering the reaction between FeO and $SiO_2$ thus the formation of $FeO.SiO_2$ was depressed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.507-510
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• 2008

Characteristics of an autothermal reformer at various operating parameters have been studied in this paper. Numerical method has been used, and simulation model has been developed for the analysis. Full Combustion reaction, Steam Reforming(SR) reaction, Water-Gas Shift(WGS) reaction, and Direct Steam Reforming(DSR) reaction are assumed as dominant chemical reactions in the autothermal reformer. Simulation results are compared with experimental results for code validation. Operating parameters of the autothermal reformer are inlet temperature, Oxygen to Carbon Ratio(OCR), Steam to Carbon Ratio(SCR), and Gas Hourly Space Veolcity(GHSV). SR reaction rate decreases with low inlet temperature. If OCR is increased, $H_2$ yield is increased but optimal point is suggested. WGS reaction is activated with high SCR. When GHSV is increased, reforming efficiency is increased but pressure drop may decrease the system efficiency.