• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.485-490
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• 2004

Sawtooth mixing device used in a non-premixed burner is evaluated for flame stabilization and NO$_{x}$ reduction. Three mixers with different blade angles are tested. Methane is delivered through the fuel jet and air passes through the co-flow annulus. The flame mode changes (attached flame, lifted flame and extinction) against the fuel flow speed are measured, and the stability diagram is drawn. Moreover, by traversing thermocouple and sampling probe in the flame, the distribution of temperature and NO$_{x}$ mole fraction are measured. With the change in blade angle, flame shape, flame stabilization, the distribution of temperature and NO$_{x}$ mole fraction are changed considerably.rably.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.4 s.346
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• pp.8-15
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• 2006

In this paper, the 94 GHz, low conversion loss, and high isolation single balanced mixer is designed and fabricated using GaAs-based metamorphic high electron mobility transistors (MHEMTs) with 70 nm gate length and the hybrid ring coupler with the micromachined transmission lines, dielectric-supported air-gapped microstrip lines (DAMLs). The 70 nm MHEMT devices exhibit DC characteristics with a drain current density of 607 mA/mm an extrinsic transconductance of 1015 mS/mm. The current gain cutoff frequency ($f_T$) and maximum oscillation frequency ($f_{max}$) are 320 GHz and 430 GHz, respectively. The fabricated hybrid ring coupler shows wideband characteristics of the coupling loss of $3.57{\pm}0.22dB$ and the transmission loss of $3.80{\pm}0.08dB$ in the measured frequency range of 85 GHz to 105 GHz. This mixer shows that the conversion loss and isolation characteristics are $2.5dB{\sim}>2.8dB$ and under -30 dB, respectively, in the range of $93.65GHz{\sim}94.25GHz$. At the center frequency of 94 GHz, this mixer shows the minimum conversion loss of 2.5 dB at a LO power of 6 dBm To our knowledge, these results are the best performances demonstrated from 94 GHz single balanced mixer utilizing GaAs-based HEMTs in terms of conversion loss as well as isolation characteristics.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.173-180
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• 2017

In this study, air sampling locations in the stack of the Advanced Fuel Science Building (AFSB) at the Korea Atomic Energy Research Institute (KAERI) were assessed according to the ANSI/HPS N13.1-1999 specification. The velocity profile, flow angle and $10{\mu}m$ aerosol particle profile at the cross-section as functions of stack height L and stack diameter D (L/D) were assessed according to the sampling location criteria using COMSOL. The criteria for the velocity profile were found to be met at 5 L/D or more for the height, and the criteria for the average flow angle were met at all locations through this assessment. The criteria for the particle profile were met at 5 L/D and 9 L/D. However, the particle profile at the cross-section of each sampling location was found to be non-uniform. In order to establish uniformity of the particle profile, a static mixer and a perimeter ring were modeled, after which the degrees of effectiveness of these components were compared. Modeling using the static mixer indicated that the sampling locations that met the criteria for the particle profile were 5-10 L/D. When modeling using the perimeter ring, the sampling locations that met the criteria for particle profile were 5 L/D and 7-10 L/D. The criteria for the velocity profile and the average flow angle were also met at the sampling locations that met the criteria for the particle profile. The methodologies used in this study can also be applied during assessments of air sampling locations when monitoring stacks at new nuclear facilities as well as existing nuclear facilities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1354-1360
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• 2010

The purpose of this study is to analyze the behavior of swine slurry wastewater from bogen, in the treatment of Aerobic Liquid-Composting treatment by Aerobic Liquid-Composting using a mixer and Micro Air Diffusion pH level was at the beginning and its rise was seemingly related to VFA. It appears that removal of BOD and COD are more effective by Aerobic than by Anaerobic. In terms of removal efficiency, it shows 70.9% of BOD and 39% of COD in M.A+Mix and 67.8% of BOD and 19% of COD in M.A. $NH_3-N$ decreases in all conditions, which is caused by both the characteristic of nitrogen and the rise of pH. $NO_3-N$ increases in all conditions. It is judged that the accumulation of $NO_3-N$ affects the reduction of the ratio of denitrification. In the result of the analysis of Manure in swine slurry of liquified fertilizer ingredients, content of Manure in swine slurry of liquified fertilizer ingredients in aerobic conditions (M.A+Mix) is higher than anaerobic conditions.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.30-35
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• 1999

Since LPG has a higher octane number and a lower maximum combustion temperature than gasoline it is getting more popular for reducing emissions from the vehicle This paper when an LPG engine works in the range of idle analyzed the operating range preciously an provides reducing method of emissions for the LPG engine. An electronic control unit(ECU) for the LPG engine using a feedback mixer is presented. The ECU is built by using a microcontroller MC68HC05. A PI-controller is imple-mented in the ECU in order to handle to handle Air/Fuel ration control. The experimental results exhibit that the required engine performance are satisfied at idle.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.5
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• pp.327-333
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• 2008

The purpose of this study is to develop a paddle-type dryer and to commercialize the dryer, in which mixing and drying can be done simultaneously. According to a performance test, a newly-designed paddle-type dryer can dry Chitosan salt to a low moisture contents below 0.3%. Also the newly-designed dryer can dry air pollution materials, because the dryer can operate in a closed system. The economic efficiency of a newly-designed system and an existing system was compared in a performance test. As a result, the economic efficiency of a newly-designed system was higher than an existing system. In conclusion, it is thought that the newly-designed system has a high commercial value.

• Food Science and Preservation
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• v.7 no.4
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• pp.389-394
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• 2000

To utilize deteriorated sweet persimmon(Diospyros kaki T.) effectively, this study was investigated about the effective (Dying method of the powder. Chemical components, minerals, fatty acids and amino acids of hot-air dried and freeze dried conditions were determined Sample conditions used on analysis as follow; pretreatments of hot-air dry and freeze dry were soft, soft+peel, mixer, mixer+peel. The contents of crude protein, crude lipid, crude ash of hot-air dry were 0.9-1.1%,15.0-39.0% and 2.3-3.3%, respectively. And those of freeze dry were 1.3-2.2%, 27.-49.0% and 2.5%, respectively. Potassium, magnesium, phosphorus, calcium and sodium content in hot-air dry and freeze dry were high. Other minerals were less than 3.00ppm in all conditions. The major fatty acid contents were detected capric acid(C$\^$10:0/), lauric acid(C$\_$l2:0)/, tridecanoic acid(C$\_$13:00/), palmitic acid(C$\_$l6:00/), palmitoleic acid(C$\_$l6:1/), oleic acid(C$\_$18:1), linoleic acid(C$\_$18:2/), linolenic acid(C$\_$18:3/). The essential amino acids such as aspartic acid, threonine, serine, glutamic acid, glycine, alanine, valine, methirmine, isoleucine, leucine, tryosine, phenylalanine, histidine, lysine, arginine in freeze dry were contained richly. On the basis of chemical analysis, hot-air dry method will have to supply the additional different method, because simple hot-air dry method was shorten the dry time but had many problems. Therefore, the effective drying method considering changed color and nutrition was shown freeze dry method.

• International Journal of Automotive Technology
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• v.7 no.4
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• pp.407-413
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• 2006

The liquefied petroleum gas(LPG), mixture of propane and butane, has the potential to reduce toxic hydrocarbon emissions and inhibit ozone formation due to its chemical composition. Conventional mixer systems, however, have problems in meeting the future lower emission standards because of the difficulty in controlling air-fuel ratio precisely according to mileage tar accumulation. Liquid Phase LPG injection(LPLi) system has several advantages in more precise fuel metering and higher engine performance than those of the conventional mixer type. On the other hands, leakage problem of LPLi system at the injector tip is a main obstacle for meeting more stringent future emission regulations because these phenomena might cause excessive amount of THC emission during cold and hot restart phase. The main focus of this paper is the development of a leaked fuel recirculation system, which can eliminate the leaked fuel at the intake system with the activated carbon canister. Leaked fuel level was evaluated by using a fast response THC analyzer and gas chromatography. The result shows that THC concentration during cold and hot restart stage decreases by over 60%, and recirculation system is an effective method to meet the SULEV standard of the LPLi engine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1175-1178
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• 2005

Brittle materials, especially single-crystal silicon wafer, are widely used for sensors, IC industry, and MEMS applications. e general machining process of crack easy materials is by chemical agents, but it is hazardous and time consuming. Also, it is difficult to get high aspect ratio micro structure. As an alternative tool, an AJM(Abrasive jet machining) is promising method in terms of high aspect ratio and production cost. In this study, to get more precise detail compared to general AJM, photo polymer mask, SU-8, used in photolithography was applied in AJM. Process parameters such as abrasive diameter, air pressure, nozzle diameter, flow rate of abrasive in AJM and a variety of conditions in spin coating were decided. Finally, micro channel and mixer was fabricated to see the efficiency of the AJM with photo polymer mask.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.3
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• pp.182-188
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• 2004

We demonstrate a $2.1\;{\times}\;1.0\;{\times}\;0.1cm^3$ sized compact transmitter using LTCC System-in-Package (SiP) technology for 60GHz-band wireless communication applications. For low-attenuation characteristics and resonance suppression of the SiP, we have proposed and demonstrated a coplanar double wire-bond transition and novel CPW-to-stripline transition integrating air-cavities as well as novel air-cavities embedded CPW line. The fabricated transmitter achieves an output of 13dBm at a RF frequency of 62GHz, an IF frequency of 2.4GHz, and a LO frequency of 59.6GHz. The up-conversion gain is 11dB, while the LO signal is suppressed with the image rejection mixer below -21.4dBc, and the image and spurious signals are also suppressed below -31dBc.