• 오토저널
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• 제11권6호
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• pp.48-56
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• 1989

A shock tube technique was developed in which a freely falling droplets column produced by an ultrasonic atomizer was ignited behind reflected shock. In the present study, the effects of turbulent mixing on the ignition delay of a cetane was decided, also, ignition process was investigated. For the purpose of disturbance of droplets column and mixing, authors installed turbulent lattice in shock tube. Usually, the ignition delay is so called Arrhenius plot which found break point in the Arrhenius plot on the high temperature side. The rate of misfiring increased rapidly below 1080K, but ignition took place from 838k and luminous flame was seen to spread over the whole section by turbulent lattice. Length, from end plate to turbulent lattice, was varied with 60,40,20mm. Also, ignition process was detected by Photo transistor. As a result, it was found that physical factors changed ignition delay greatly and turbulent mixing had a considerable effects in the ignition process.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.431-437
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• 1998

This study was performed to ascertain the three-dimensional effect of the crack reduction and the restrained effect of crack growth, and to yield a suitable mixing ratio of the synthetic fiber reinforced soil. The results of the study are as follows ; 1) The synthetic fiber has the resisting force for crack because of the adhesion due to the attraction of soil particles. 2) As the synthetic fiber length and the mixing ratio are increased, mono filament synthetic fiber reinforced soil is increased the effects of crack reduction and the restraint of crack growth. 3) The fibrillated synthetic fiber is more effective than mono filament synthetic fiber for crack. 4) A suitable mixing ratio of synthetic fiber reinforced soil is 0.5% of the fibrillated synthetic fiber.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.382-387
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• 1998

Triaxial compression tests were run to study on the undrained strength characteristics of fiber mixed kaolin clay(Hadong). The influence of various test parameters such as amount and aspect ratio(ratio of length to diameter) of fiber, confining stress was also investigated. Test results showed that the increase in aspect ratio was increased in deviator stress at failure, but no effect on pore water pressure at failure. Deviator stress at failure was also increased at 0.5％ mixing ratio(weight fraction of fiber to that of soil solid) of fiber but it was, thereafter, decreased and wits reached to constant after 2％ mixing ratio. On the contrary, Pore water pressure at failure was increased as mixing ratio of fiber was greater than 1%. Deviator stress and pore water pressure of both clay and fiber mixed clay(FMC) at failure were increased as confining stress was increased. Deviator stress of FMC at failure was about 10％ larger than that of clay, but pore water pressure of FMC at failure was almost similar to that of clay.

• 전기의세계
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• 제25권6호
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• pp.74-80
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• 1976

The temperature rise of the mortars while are being irradiated by ultrasonic waves and immersed in a liquid medium, are measured. The mixing ratios of sand to cement are varied for the different mortars. The results of the experiment are as follows, 1. The temperature rise of the mortar is decreased as themixing ration (S/C) is increased. 2. Thd temperature rise of the specimen is increased as its length is increased. 3. The surface conditions, either smooth or rough, may not have much influence on the temperature rise of the mortar. 4. The initial slope of temperature rise may not have much effect of the viscosity of liquid. The results, describes above, appear well coincide with the theory that the temperature rise is attributed mainly to the absorption heating. Since the absorption heating of the mortars varies with the mixing ratios of sand to cement, the strength of them would be estimated by means of irradiation of ultrasonic waves on the specimen.

• Ocean and Polar Research
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• 제22권1호
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• pp.45-56
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• 2000

Hydrodynamic mixing characteristics of submerged effluent discharges into Masan Bay were investigated by both field observations and numerical model simulations. CORMIX model, a length-scale mixing model, was adopted to obtain the near-field dilution and wastefield characteristics of the effluent discharges into Masan Bay. Model predictions of the near-field dilution rates were in a good agreement with field observations in summer and winter seasons. Seasonal variations in the dilution rates showed that the highest dilution rate was obtained in winter while the lowest dilution rate was in summer. As the effluent discharges are increased with the treatment capacity expansion to be completed by 2011, the dilution rates are expected to be much reduced and the near-field stability of the wastefields will become unstable due to the increased effluent discharges.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.233-236
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• 2003

The micro-stereolithography technology made it possible to fabricate a freeform 3D micro-structure. Using this technology, two kind of applications were fabricated and tested: micro-lens and micro-mixers. The focal length and f-number of the micro-lens were 5 mm and 2.5, respectively. The focusing ability of the micro-lens was verified by defocusing the He-Ne laser beam after passing the lens. Two mixers are Kenics micro-mixer and BEKM. BEKM is a modified Kenics micro-mixer by introducing barriers on the pipe walt periodically to enhance the mixing via the chaotic mechanism in the helical flow of Kenics micro-mixer. Experimental result shows good mixing performance of developed mixers. Especially, the BEKM shows better mixing performance then Kenics micro-mixer.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.137-142
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• 1997

From the results of study on the electrical characteristics of heat-generation mortar used graphite as fine aggregates is summerized as following. The primary purpose of this study is the mixing ratio of graphite (35%, 50%/Sg), curing conditions (autoclave, steam, surface, underwater) and shape change (length, section of the electric heat-generation mortar). In case of the test condition with the steam curing condition appearance to most excellent heat-generation reproducibility. And temperature a coefficient of electric heat-generation mortar change from is in inverse proportion to the temperature a coefficient of direct proportion as the ratio of graphite mixing increased.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.9-10
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• 2017

In case of the concrete is poured into the HPC(Hollow Precast Concrete) column, the shrinkage condition of the HPC surface and the infilled concrete may be different, causing an interfacial space and deteriorating the integration performance. In this study, manufacturing HPC column mold and and the drying shrinkage properties with the charging concrete were examined. As a result, case of the shrinkage reducing agent showed the best drying shrinkage reduction effect. In the case of the expansive agent, the length change was lower than that of plain, but the difference from the shrinkage reducing agent was large, so it is considered that mixing condition of expansion mixing condition should be improved.

• International Journal of Air-Conditioning and Refrigeration
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• 제9권2호
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• pp.77-84
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• 2001

Experimental and computational studies were carried out to investigate the turbulent heat transfer enhancement of the cooling system in nuclear reactor by large scale vortex generation. The large scale vortex motion was generated by rearranging the inclination angels of mixing vanes to the coordinate direction. Axial development of mean and turbulent velocities in the subchannels were measured by the 2-color LDV system. Eddy diffusivity concept based on $\kappa{-}\varepsilon$ model was employed to calculate the turbulent heat and momentum transfers in the subchannel. The turbulences generated by split mixing vanes has small length scales so that they maintain only about $10D_H$ after the spacer grid. On the other hand, the turbulences generated by the large scale vortex motions continue longer and remain up to $25D_H$ after the spacer grid.

• 설비공학논문집
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• 제12권11호
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• pp.1004-1011
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• 2000

Experimental and computational studies were carried out to confirm the turbulent enhancement of the cooling system of nuclear reactor by large scale vortex generation in nuclear fuel bundle. The large scale vortex motions were generated by rearranging the inclination angles of mixing vanes to the coordinate directions. Axial development of mean and turbulent velocities in the subchannels were measured by the 2-color LDV system. Eddy diffusivity heat flux model and $k-varepsilon$ model were employed to analyze the turbulent heat and fluid flows in the subchannel. The turbulence generated by split mixing vanes has small length scales so that they maintain only about $10 D_H$ after the spacer grid. On the other hand, the turbulences generated by the large scale vortex continue more and remain up to $25 D_H$after the spacer gird.