• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.807-808
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• 2010

• Journal of the Korean Ceramic Society
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• v.24 no.2
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• pp.161-169
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• 1987

An experimental study of the characteristics and the behavior of flames, and the aerodynamic flow pattern was carried out in the present work on a down draft kiln for gas firing. The aim of this work is to establish a behavior of flames and to know the extent to which the flow pattern is affected by the height of baffle plate. The measurements of temperature, concentrations of fuelgas, and kiln pressure were conducted at different temperature in kiln, and at different height of baffle plate. From the obtained results, it was found that the characteristics of thestagnation zone are greatly affected when changing over the height of baffle plate, and the best condition of that was 115m/m.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2003.04a
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• pp.164-170
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• 2003

In this paper, we studied on the firing characteristics and electrical fire analysis of power cord deteriorated by thermal stress. The cross section of PVC insulating cord deteriorated by indirect flame decreased through heat convection. PVC insulating cord deteriorated by direct flame was bumpy shape. The exothermic peak of normal cord was shown at ($526.7^{\circ}C$), but the peaks or on(heat treatment temperature) ($150^{\circ}C$) cord was shown at ($299.6^{\circ}C$) and [$502.2^{\circ}C$]. The exothermic peaks according to high temperature were similar to those of amorphous carbon. In the FT-IR analysis, the absorption peak of normal cord indicated double bond of oxygen and carbon in benzene ring at 1720.0$cm^{1}$. As the HTT was high, the height of characteristic peak decreased and the peak of carbonyl group was shown at about 1625.7$cm^{-1}$. The characteristic peak of single bond(O-H) was shown at about 3479.2$cm^{-1}$. In case of the internal part of wire covering deteriorated by over current, the characteristic peak were shown at about 3417.3$cm^{-1}$ and 1600.2$cm^{-1}$. The above results show that we can distinguish the differences according to the fire pattern through the internalㆍexternal analysis of wire covering deteriorated by heat.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.209-216
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• 2014

The screen printed technique is one of the electrode forming technologies for crystalline silicon solar cell. It has the advantage that can raise the production efficiency due to simple process. The electrode technology is the core process because the electrode feature is given a substantial factor (for solar cell efficiency). In this paper, we tried to change conditions such as squeegee angle $55{\sim}75^{\circ}$, snap off 0.5~1.75 mm, printing pressure 0.6~0.3 MPa and 1.6~2.0 mm finger spacing. As a result, the screen printing process showed an improved performance with an increased height higher finger height. Optimization of fabrication process has achieved 17.48% efficiency at screen mesh of 1.6 mm finger spacing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.105-110
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• 2010

Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.200-203
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• 2011

Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.586-591
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• 1999

Mixed-firing of a bituminous and an anthracite coal carried out in a batch fluidized bed combustor(0.109 m-I.D., 0.9 m-height). Effect of particle size an mixing fraction of anthracite and bituminous coal combustion characteristics were studied. The temperature profiles and pressure fluctuation properties were measured to interpret the combustion characteristics in a batch fluidized bed combustor. The used domestic anthracite coal has heating value of 2010 kcal/kg and the imported high-calorific bituminous coal has heating value of 6520 kcal/kg. The combustion characteristics in a batch fluidized bed combustor could be interpreted by using pressure fluctuation properties and temperature increasing rates. It was found that the optimum anthracite mixing percentage could be predicted analyzing the combustion rate and fluidization characteristics, The optimum mixing fraction was about 30 %. The different burning region of fluidized bed combustor was measured by temperature increasing rates.

• Journal of Plant Biology
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• v.14 no.3
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• pp.36-42
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• 1971

The effects of irregular burning of vegetation by man were studied in relation to composition and productivity in a non-agricultural montane grassland in the Chongsun area, Kangwon-Do, Korea. The floristic composition in all study area includes 38 species. Three of the stations are dominated by Arundinella hirta and one is dominated by Miscanthus sinensis. The standing crop of the first station, which was fired in early spring, 1970, was 358.7g/$m^2$ to 497.5g/$m^2$; that of the second station, fired in late 1969 was 351. 5g/$m^2$; the third station, fired sometime in 1968, had a standing crop of 314.5g/$m^2$ to 397.1/$m^2$; the fourth station, having had no recent fires, had a standing crop of 370.0g/$m^2$ to 448.0g/$m^2$. The daily productivity shows a maximum of 6.03g/$m^2$ in the first station, and a minimum of 0.85g/$m^2$ in the fourth station. The productivity of grassland in the study area is at a maximum during July and August because of much precipitation, and decreases rapidly in the months to follow. The productive structure of the first and fourth stations is shown in Fig. 2 and 3. At the first station the maximum height attained by the plants was 180cm. In the height range of 50cm to 100cm there was a maximum of assimilative organs (5.6g/0.25$m^2$$\times$10cm), while in the height range below 50cm there was a maximum of non-assimilative organs (13.0g/0.25$m^2$$\times$10cm). At the fourth station, which has not been fired recently, the maximum height reached by the plants was commonly below 100cm. The assimilative organs showed a maximum abundance in the height range of 40cm to 50cm (4.5g/0.25$m^2$$\times$10cm). while the non-assimilative organs showed their greated abundance in the height range below 10cm (6.0g/0.25$m^2$$\times$10cm). There was a direct relationship between daily productivity and organic matter, available phosphorous, exchangeable calcium and potassium. It appears that the nutrients provided by the ash created in the firing of the study can be an important factor in the productivity of these grasslands.

• Clean Technology
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• v.23 no.1
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• pp.80-89
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• 2017

The bubbling fluidized bed (BFB) reactor with a diameter of 0.1 m and a height of 1.2 m was used for experimental study of co-firing and emission characteristics fueled by sewage sludge (SS) and wood pellet (WP). The facility consists of a fluidized bed reactor, feeding system, cyclone, condenser and gas analyzer, The mean particle diameter and minimum fluidization velocity are $460{\mu}m$ and $0.21ms^{-1}$ respectively. SS produced from Korea and WP from Canada were examined. The various mixing ratios of WP were 20, 50, and 80% based on HHV. The equivalence ratio of 1.65, reactor temperature of $800^{\circ}C$, air flow rate of $100Lmin^{-1}$, and fluidization number of 4 were fixed in the BFB experiment. In TGA, the range of combustion temperature of SS was wider than that of WP. It represents that the combustibility of WP is higher than that of SS. The BFB reactor temperature was maintained between 800 and $900^{\circ}C$. CO emission of SS was high because of lower combustibility. $NO_X$ and $SO_X$ formation of SS were higher than that of WP since high nitrogen and sulfur contents of SS. CO, $NO_X$, and $SO_X$ formation were suppressed as the mixing ratio of WP was increased. The slagging and fouling tendencies show high in all test conditions.

• Journal of Technologic Dentistry
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• v.31 no.4
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• pp.15-23
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• 2009

The aim of this study was to evaluate the bond strength of using a Au bonding agent applied on cp-Ti and nonprecious metal-gold-ceramic system. Metallic frameworks(diameter: 5mm, height: 20mm)(N=56, n=7per group) cast in Ni-Cr alloy, Co-Cr alloy and cp-Ti were obtained using acrylic templates and airborne particle abraded with $110{\mu}m$ aluminum oxide. Au bonding agent was applied on wash opaque firing as intermediate layer. SEM and SEM/EDS line profile were performed on the cutting the cross-section of the metal substrate-porcelain with intermediate Au coating. Groups were tested using shear bond strength(SBS) testing at 0.5mm/min. The mean SBS values for the ceramic-Au layer-metal combination were significantly higher than those ceramic-metal combination. While ceramic-Au layer-cp-Ti combinations failed to increase bond strength instead of using a titanium bonding porcelain. The appication of using Au intermediate layer significantly improve the bond strength combination with metal-ceramic system.