• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.555-560
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• 2002

Numerical simulations of freely propagating flames burning stoichiometric CH$_4$/O$_2$/$N_2$mixtures are performed at atmospheric pressure in order to understand the effect of the $O_2$enrichment level on CH$_4$/Air flame. A chemical kinetic mechanism is employed, the adopted scheme involving 54 gas-phase species and 632 forward reactions. The calculated flame speeds are compared with the experiments for the flames established at several $O_2$enrichment level, the results of which is in excellent agreement. As a result of the increased $O_2$enrichment level from 0.21 to 1, the mole fraction of CO in the burred gas is increased. The flame speed and the temperature in the burned gas are also increased, but the thickness of the flame is severely shrunken in the preheat region. The maximum of the calculated EINO is obtained around 0.6 and 0.7 of the $O_2$enrichment level in cases of flames for fuel-lean mixtures.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.2
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• pp.81-91
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• 2012

As the recent development of the ubiquitous computing environment, u-GIS is being highlighted as the core technology of the ubiquitous computing environment, and thereby, studies on spatio-temporal data are being actively conducted. In this u-GIS environment, it is still difficult for existing mobile devices to efficiently manage the massive spatio-temporal data of u-GIS that are increasing day by day. Therefore, this paper develops a spatio-temporal query processing system for mobile devices in order to solve the problem. The system provides various spatio-temporal operators to insert/delete/update/search spatio-temporal data and supports a query optimization function that uses a spatio-temporal index for the flash memory and a spatio-temporal histogram for guaranteeing query execution speed. Lastly, by applying the spatio-temporal query processing system developed in this paper to the virtual scenario, this paper has proved that the system can be utilized in various application fields necessary to process spatio-temporal data in the mobile environment.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.285-290
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• 2016

To improve properties of epoxy composites, surfaces of the illite and carbon nanotube (CNT) were treated by fluorine gas. The fluorinated illite and CNT were then characterized by X-ray photoelectron microscopy (XPS) and the mechanical and thermal properties of their composites were evaluated. The tensile and impact strengths and thermal stability of the composites increased upto about 59%, 18% and 124%, respectively compared to those of the neat epoxy. Improvements of mechanical and thermal properties in the composites were attributed that the fluorination of illite and carbon nanotube helps to enhance the dispersion in epoxy resin and interfacial interaction between them.

• Fire Science and Engineering
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• v.30 no.6
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• pp.9-13
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• 2016

Anti-oxidation and flame resistant polyurethane nanofibers were prepared by electrospinning and aluminum hydroxide addition. Electrospinning was carried out under the following procedure conditions; applied voltage, 20 kV; polymer solution feeding rate, 1.2 ml/h; collector rolling speed, 120 rpm; and tip to collector distance, 15 cm. Aluminum hydroxide was added to the prepared polymer solution for electrospinning to enhance the oxidation and flame resistant properties. The thermal properties were investigated by thermogravimetric analysis to determine the polymer decomposition temperature, integral procedure decomposition temperature, final decomposition temperature, and remaining amount after thermal decomposition. The activated energy for polymer degradation was also investigated using the Horowitz-Metzger equation. The activation energy increased to more than 50%. The thermal properties of the polyurethane nanofibers were improved by a hydration reaction during the thermal decomposition of aluminum hydroxide around $300{\sim}500^{\circ}C$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.1
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• pp.31-38
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• 2002

In order to improve the 0.35 $mutextrm{m}$-via hole etching process the etching characteristic of the gas $C_2F_{6}$ has been analyzed. The samples were triple-layer films(TEOS/SOG/TEOS) on 8-inch wafers and the orthogonal array matrix technique was used for the process. The equipment for etching was the transformer coupled plasma (TCP) source which is a type of high density plasma(HDP). This experiment showed the etching rate for $C_2F_{6}$ was 0.8 $mutextrm{m}$/min-1.1 $mutextrm{m}$/min and the measured uniformity was under $pm$6.9% in the matrix window. The CD skew comparison between pre and post-etching was under 10% which is an outstanding results in the window of profile in anisotropic etching. There was no problem in C2F6 with the flow rate of 20sccm, but when 14sccm of $C_2F_{6}$ was supplied there was a recess problem on the inner wall of SOG film. Consequently the etching characteristic of $C_2F_{6}$ shows a fast etching rate and a very wide process window in HDP TCP.

• Journal of the Korean Chemical Society
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• v.38 no.4
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• pp.302-308
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• 1994

Homogeneous catalytic oxidation of hydrazobenzene was investigated by employing pentadentate Schiff base complexes such as [Co(II)(Sal-DPT)(H$_2$O)] and [Co(II)(Sal-DET)(H$_2$O)] in oxygen-saturated methanol solvent. The oxidation product of hydrazobenzene(H$_2$AB) was trans-azobenzene(trans-AB). The rate constants of oxidation reaction measured by UV-visible spectrophotometry were observed as $6.06{\times}10^{-3}sec^{-1}$ for [Co(II)(Sal-DPT)(H$_2$O)] and $2.50{\times}10^{-3}sec^{-1}$ for [Co(II)(Sal-DET)(H$_2$O)]. The mechanism of oxidation reaction for H$_2$AB by homogeneous activated catalysts has been proposed as following. H$_2$AB + Co(II)(L)(H$_2$O) + O$_2$ $\rightleftharpoons^K_{MeOH}Co(III)(L)O_2{\cdot}H_2AB + H_2O\longrightarrow^{k}Co(II)(L) + trans-AB + H_2O_2$ (L: Sal-DPT and Sal-DET)

• PNF and Movement
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• v.15 no.3
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• pp.343-351
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• 2017

Purpose: This study aimed to suggest effective lunge exercise methods for various purposes by comparing differences in the muscle activity of thigh and plantar pressure according to changes in base of support during lunge exercises. Methods: The subjects were 20 college students who agreed to participate in the experiment. They performed three types of lunges-a basic lunge (BL), wide lunge (WL), and narrow lunge (NL). In a static position during each lunge, the muscle activity of the thigh and plantar pressure were measured. Each movement was maintained for 7 seconds, and the muscle activity for the 3 seconds in the middle was measured and analyzed. The plantar pressure was divided into six areas for analysis. The subjects randomly performed the lunges to prevent the influence of an experimental sequence. Each movement was performed three times, and the mean value of the three measurements was analyzed. Results: The analysis of muscle activities in the thigh during the three lunge movements showed statistically significantly higher muscle activity of biceps femoris in WL and NL than BL. Moreover, the analysis of plantar force showed statistically significant differences between BL and WL and WL and NL on the medial-forefoot and medial-midfoot, as well as between BL and WL and BL and NL on the lateral-midfoot. The analysis of plantar contact pressure exhibited statistically significant differences between BL and NL and WL and NL on the medial-forefoot, as well as a statistically significant difference between WL and NL on the medial-midfoot and lateral-hindfoot. Conclusion: This study suggests that changing the base of support during lunges can be useful to suit the purposes of various rehabilitation programs.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.328-333
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• 2020

In this study, blended feedstock derived pyrolyzed fuel oil (PFO) and coal-tar was prepared to produce a pitch by thermal polymerization reaction for manufacturing artificial graphite materials. The aromaticity value of 0.355 and 0.818 was obtained for PFO and coal-tar, respectively. In addition, PFO and coal-tar exhibited the difference tendency of weight loss curve for thermogravimetric analysis, which is related to the structural stability depending on the aromaticity and functional groups. The production characteristics confirmed that the pitch derived PFO showed lower production yield and higher softening point than that using blended feedstock. In particular, when comparing P360 (138.5 ℃) and B420 (141.4 ℃) having similar softening points, the production yields of both pitches exhibited 29.89 and 49.03 wt%, respectively. This is mainly due to the blending of PFO and coal-tar having high pitch polymerization reactivity including a large amount of alkyl groups and coal-tar having high thermal stability. This phenomenon indicated that the increased production yield is because of a synergic effect of both the high reactivity of PFO and thermal stability of coal-tar.

• Tunnel and Underground Space
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• v.17 no.5
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• pp.360-371
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• 2007

This paper presents an application of drainage control and slope stability by GIS-based hydrological modeling to control the surface water from an operational point of view. This study was carried out on a region of Pasir open-pit coal mine, Indonesia. A detailed topographical survey was performed at the study area to generate a reliable DEM (Digital Elevation Model). Hydrology tools implemented in ArcGIS 9.1 were used to extract the characteristics of drainage system such as flow direction, flow accumulation and catchment area from DEM. The results of hydrological modeling and spatial analysis showed that current arrangement of pumping facility is not suitable and some vulnerable places to erosion exist on the bench face due to concentrated surface runoff. Finally, some practical measures were suggested to optimize the design of drainage system and to monitor the slope stability by the surface water management at the study region during heavy rainfall.

• The Journal of Korean Medicine
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• v.17 no.2 s.32
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• pp.203-213
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• 1996

Experimental studies were done to research the clinical effect of Insamyounpaesan and Insamyounpaesangamibang on viscousity of mucin solution, pulmonary thromboembolism, oxygen consumption in $O_3$ - exposed and Lung TBA in rats and mice. The result was obtained as follows: 1. In the effect of Insamyounpaesan and I nsamyounpaesangami-bang on the rate of viscousity sampled from mucin, Insam-younpaesan and Insamyounpaesangamibang were revealed to have a significant effect of decreasinf the rate of viscousity (p<0.05). 2. In the effect of Insamyounpaesan and Insamyounpaesangami-bang on sodium arachidonic acid induced pulmonary thrombo-embolism, Insamyounpaesan and Insamyounpaesangarnibang were revealed to have an effect of increasing the number of survival(p<0,05), but were not significant. 3. In the effect of Insamyounpaesan and Insamyounpaesangami-bang on ADP induced pulmonary thromboembolism, Insam-younpaesangamibang were revealed to have an effect of increasing the number of survival(p<0.05), but were not significant. 4. In the effect of Insamyounpaesan and Insamyounpaesangami-bang on oxygen cansumption values in rats exposed, Insamyounpaesan and Insamyounpaesangamibang were revealed to have a significant effect on the care of lung damages (p<0.05), but were not significant by Duncan's multiple comparision test. 5. In the effect of Insamyounpaesan and Insamyounpaesangami-bang on the lung TBA values in rats exposed $-O_3$, Insam-younpaesangamibang were revealed to have a significant effect (p<0.05) on the care of lung damages. In connection with the results of the studies, Insamyounpaesan and Insamyounpaesangamibang are concluded to be effective on the treatment of cough and lung and respiratory organ damages.