• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.130-136
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• 1981

Rice hull was reduced to ash by carbonization grades to illcuidate alkalinity increase and extract of inorganic nutrients in the rice hull charcoal. Alkaline reaction of water extraction was neutral at less carbonized charcoal, but much carbonized ash from 65% weight loss reached over 10 of pH value, also origin shape of rice hull was maintained until near 65% carbonized grade. Therefore, physical properties sustained good condition for seedling bed. The more charcoal carbonized to ash, the pH value and concentration of inorganic nutrient in their extracts were increased gradually. Nitric acid concentrations for neutralizing extract from charcoal were stronger in proportion to the carbonized grade but 0.1 N nitric acid solution was very reasonable to neutralize the 65% carbonized charcoal for mixing with heavy texture acidy soil(pH 5.3) of uncultivated deep horizon to transplant the tobacco seedlings. Volume ratio mixing for seedling bed is adequate at five of ash to one of acid solution. Neutralization with nitric acid solution also accelerated extraction of the inorganic nutrient in rice hull ash. Tobacco seedlings grown on bed mixed with neutralized rice hull charcoal and soil had shown better results on the agronomic measurement than alkaline ash bed, and phosphorus and cations were uptaken more amounts.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.917-922
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• 2015

The goal of this study is to consider the application of alternative blended fuel to diesel engine. In this study, as the test fuels, we use a blended fuel mix of diesel and hydrogen peroxide. As the primary variable, we vary the mixing ratio of diesel and hydrogen peroxide in the experimental and numerical analysis. We perform an evaporative behavior characteristics analysis of the emulsified fuel using the Schlieren method. The numerical analysis was carried out based on results obtained from the experimental analysis using the commercial code(ANSYS CFX). Consequently, we found that the micro-explosion depends on the fraction of hydrogen peroxide, and we propose a numerical method for the quantitative evaporation analysis of emulsified fuel droplets using the calculation of the volume fraction in the oil domain.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.3
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• pp.147-155
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• 2016

Industry 4.0's goal is the 'Smart Factory' that integrates and controls production process, procurement, distribution and service based on the fundamental technology such as internet of the things, cyber physical system, sensor, etc. Basic requirement for successful promotion of this Industry 4.0 is the large supply of semiconductor. However, company I who produces dicing blades has difficulty to meet the increasing demand and has hard time to increase revenue because its raw material includes high price diamond, and requires very complex and sensitive process for production. Therefore, this study is focused on understanding the problems and presenting optimal plan to increase productivity of dicing blade manufacturing processes. We carried out a study as follows to accomplish the above purposes. First, previous researches were investigated. Second, the bottlenecks in manufacturing processes were identified using simulation tool (Arena 14.3). Third, we calculate investment amount according to added equipments purchase and perform economic analysis according to cost and sales increase. Finally, we derive optimum plan for productivity improvement and analyze its expected effect. To summarize these results as follows : First, daily average blade production volume can be increased two times from 60 ea. to 120 ea. by performing mixing job in the day before. Second, work flow can be smoother due to reduced waiting time if more machines are added to improve setting process. It was found that average waiting time of 23 minutes can be reduced to around 9 minutes from current process. Third, it was found through simulation that the whole processing line can compose smoother production line by performing mixing process in advance, and add setting and sintering machines. In the course of this study, it was found that adding more machines to reduce waiting time is not the best alternative.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.1-5
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• 2017

Leaking of natural gas, which is mostly methane, in a confined living space creates flammable atmosphere and gives rise to explosion accident. The minimum amount of leaked methane for explosion is highly dependent on the degree of mixing in the confined space. This paper proposes a method for estimating minimum amount of flammable gas for explosion by using Gaussian distribution explosion model(GDEM) and experimental explosion data. The explosion pressure in the confined space can be estimated by assuming the Gaussian distribution of flammable gas along the height of an enclosure and estimating the maximum amount of gas within flammable limits, combustion of the estimated gas with constant volume and adiabatic or isothermal mixing in the confined space. The predicted minimum gas amount for an explosion is tied to explosion pressure that results in a given building damage level. The result shows that very small amount of methane leaking in the confined space may results in a serious gas explosion accident. This result could be applied not only to setting the leak criteria for developing a gas safety appliance but also to accident investigating of explosion.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.188-195
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• 2014

This paper was evaluated the rheology properties according to each step of paste, mortar and HPFRCC as a part of the basic study to development of sprayed high performance fiber reinforced cementitious composites(HPFRCC) for protection and blast resistant. Rheology test results in step of paste, in case of GGBFs and FA, it showed that the plastic viscosity and yield stress reduced gradually according to the increase of mixing rate, and in case of SF, the plastic viscosity and yield stress increased radically starting from the mixing rate of 10%. Rheology test results in step of mortar, type of aggregates, it showed that particle shape and grading of aggregate is influence on plastic viscosity and yield stress, and change of volume ratio is influence on plastic viscosity than yield stress. Fluidity and rheology test results in step of HPFRCC, if after a fiber mixed, it showed that viscosity agent is more effective to improve the fluidity and fiber dispersion than superplasticizer.

• Transactions of Materials Processing
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• v.29 no.1
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• pp.11-19
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• 2020

For microstructural analysis of a friction stir welded (FSWed) joint of advanced high-strength steels, dual phase (DP) and complex phase (CP) steels, are studied. FSWed joints are successfully fabricated in the following four cases: (i) DP/DP; (ii) CP/CP; (iii) DP/CP, where the advancing side is DP and the retreating side is CP; (iv) CP/DP, where the advancing side is CP and the retreating side is DP. The stir zone (SZ) of (i) the DP/DP joint mainly consists of lath martensite, while the stir zone of (ii) the CP/CP joint consists not only of lath martensite but also of bainite. In the case of (iii) DP/CP and (iv) CP/DP, they exhibit a similar microstructure including acicular-shaped phases in the joints; however, cross-sections of the joints show differences in material mixing in each case. In (iv) the CP/DP joint, temperature towards the CP steel is sufficient to cause softening, thus leading to better mixing than that in (iii) DP/CP. The phases of the SZ in each of the four cases are formed by phase transformation during the FSWed process; however, the transformed phase volume fraction of CP steel is lower than that of DP steel, indicating that dynamic recrystallization occurs mainly in CP steel. The hardness values of the SZ are significantly higher than those of the base materials, especially, the SZ of (iii) the DP/CP joint has the highest value due to highest fraction of lath martensite.

• Journal of Powder Materials
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• v.19 no.2
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• pp.140-145
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• 2012

This paper describes the manufacturing process of tilting pad gas bearing with a diameter of 5 mm and a length of 0.5-1 mm for power MEMS (Micro Electomechanical Systems) applications. The bearing compacts with nanopowder feedstock were prepared by Ni-metal mold with 2-mold system using LIGA process. The effect of the manufacturing conditions on sintering properties of nanopowder gas bearing was investigated. In this work, Fe-45 wt%Ni nanopowder with an average diameter of 30-50 nm size was used as starting material. After mixing the nanopowder and the wax-based binders, the amount of powder was controlled to obtain the certain mixing ratio. The nanopowder bearing compacts were sintered with 1-2 hr holding time under hydrogen atmospheres and under temperatures of $600^{\circ}C$ to $1,000^{\circ}C$. Finally, the critical batch of mixed powder system was found to be 70% particle fraction in total volume. The maximum density of the sintered bearing specimen was about 94% of theoretical density.

• Applied Biological Chemistry
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• v.36 no.2
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• pp.80-85
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• 1993

Addition of the treated dietary fiber sources to wheat flour were generally decreased at Amylograph viscosity as the mixing ratio increased. Addition of the treated dietary fiber sources on the preparation of noodles increased weight and volume of cooked noodles but decreased extention force as the mixing ratio increased. The sensory test of the dietary fiber sources mixed noodles supplemented by treated soymilk residue 5% was excellent sensual properties. The properties of the dietary fiber sources mixed noodles supplemented by treated soymilk residue 10% and treated apple pomace 5% were nearly the same in the texture organoleptic properties compared with those of wheat flour noodle.

• Applied Biological Chemistry
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• v.46 no.4
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• pp.323-328
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• 2003

Wheat bran, a milling by-product of domestic wheat grains, containing approximately 42% of the total dietary fiber, was tested for the effects on bread-making properties. The amylograph peak viscosity and set bark values considerably decreased with increasing levels $(0{\sim}30%)$ of wheat bran. Adding wheat bran somewhat increased water absorption and showed no consistent effect on mixing time. Yeast-leavened breads were baked with wheat flour with up to 30% of the flour substituted with domestic wheat bran. Adding domestic wheat bran exerted detrimental effect on loaf volume and decreased sensory acceptability such as crust and crumb color, crumb grain, texture, and flavor. Wheat bran decreased lightness and imparted red and yellow tint. It was suggested that domestic wheat bran could be substituted for wheat flour at levels up to 15% without significantly depressing bread quality in the preparation of high-fiber bread. Crumb firmness of bread containing 15% wheat bran was significantly higher than that of the control bread (100% wheat flour) and increased rapidly at $2{\sim}3$ days during storage.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.7
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• pp.516-522
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• 2011

The largest problem of domestic anaerobic digestion is low digestion efficiency. Reasons of the problem would be low organic matters input, low mixing efficiency in digestion tank, refractory excess sludge etc.. In this study, screw attached disk-type concentration system and a mechanical mixing system, solubilization facility improvements were performed to solve problems. Through these improvements, the sludge conc. of the concentrator increased 2.6-fold and the volume reduction efficiency was increased 3.0-fold. In addition, the dead-space is reduced by mechanical agitation. Anaerobic digester gas production in the digestion tank is increased from $193.8m^3$ to $386.0m^3$ per day. Digestion efficiency is improved to 54.6% from 47.6%. Digestion gas production is increased from $0.30Nm^3/kg$ VS to $0.42Nm^3/kg$ VS.