• 한국안전학회지
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• 제7권3호
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• pp.73-82
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• 1992

This paper was concerned with the risk evaluation of oxidizing substances by burning test method. The samples were prepared the heaped cone-shaped mixtures of solid oxidizing sub-stance with sawdust, and ignition of the sample was made on contact with heating wire inside the combution chamber that the temperature and humidity of atmosphere can be kept at $25^{\circ}C$ and 60% respectively. Accordingly, it were measured the combustivity effect of mixing ratio and amount of sample weight on the burning rate. As a result of burning test of these samples, it could be noticed that the case when the sawdust has so and 30 wt.% in the mixing ratio shows effective combustivity, and as the amount of sample weight was increasing, It showed more rapid burning time. So the average burning time could be obtained by considering the weighting factors to the parameters of the mixing ratio and the amount of sample weight. Finally, it was compared with the effects of cation and anion of oxidizing substances and also applied analytically to the classification and evaluation of oxidizing sub-stances as dangerous goods.

• Structural Engineering and Mechanics
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• 제84권4호
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• pp.465-477
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• 2022

The formation of biopolymer-soil matrices mainly depends on biopolymer type and concentration, soil type, pore fluid and phase transfer to influence its strengthening efficiency. In this study, the physical and mechanical properties of sodium alginate (SA) treated kaolinite are investigated through compaction test, thread rolling teat, fall cone test and unconfined compression test with considering biopolymer concentration, curing time, initial water content, mixing method. The results show that the liquid limit slightly decreases from 69.9% to 68.3% at 0.2% SA and then gradually increases to 98.3% at 5% SA. At hydrated condition, the unconfined compressive strength (UCS) of SA treated clay at 0.5%, 1%, 2% and 3% concentrations is 2.57, 4.5, 7.1 and 5.48 times of untreated clay (15.7 kPa) at the same initial water content. In addition, the optimum biopolymer concentration, curing time, mixing method and initial water content can be regarded as 2%, 28 days, room temperature water-dry mixing (RD), 50%-55% to achieve the maximum unconfined compressive strength, which corresponds to the UCS increment of 593%, compared to the maximum UCS of untreated clay (780 kPa).

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.372-382
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• 2006

The DCM(Deep Cement Mixing) Method was introduced domestically in 1985 and has been applied widely to improve stability, increase bearing capacity and reduce settlement of the structure. It has been only performed by the combined equipment to improve the soft ground in coastal areas. But it has qualify-control problems such as interference of waves and improving depth, etc. Therefore DCM Barge of specialist equipment, named by Dong Ji Ho, was equipped with three mixing shafts with four rod and installed GPS system In itself, had been developed in 2005 for the purpose of solving the above problems. This paper represents about Dong Ji Ho's qualify-control system as well as it's first domestic application to in-situ trial test and the original design of the Ulsan breakwater site.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.471-474
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• 2006

The Mixer is apparatus that help precipitation or an inhomogeneous distribution of various phases to be mixed and that user makes necessary material mixing one or the other. Mainly the mixer which is used from chemical and food industry is very important system in engineering that mixes the material. The inside flow of the mixer under the actual states which put a basis in flow of the fluid is formed rotation of the impeller. The inside flow of impeller will be caused by various reasons change with shape of impeller, number of rotation, mixing material and flow pattern of free surface etc. Also mixer study depended in single-phase flow and experimental research. So the numerical analysis of flow mixing solid-fluid particle is simulated. It is become known, that the case where agitator inside working fluid includes the solid particle the sinkage reverse which the solid particle has decreases an agitation efficiency. From the research which it sees the hazard solid which examines the effect where the change of the sinkage territory which it follows agitation number of revolution and diameter of the particle goes mad to an agitator inside flow distribution - numerical analysis the inside flow distribution of liquid state with Eulerian Two-Phase Method.

• Journal of Advanced Marine Engineering and Technology
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• 제33권4호
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• pp.451-458
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• 2009

This experimental study was conducted to investigate macroscopic characteristics of the flash boiling spray with tow component mixing fuel. Homogeneous Charge Compression Ignition (HCCI) is a newer combustion method for internal combustion engines to reduce nitrogen oxide and particulate matter simultaneously. But it is difficult to put this combustion method to practical use in an engine because of such problems as instability of combustion in low load operating conditions and knocking in high load operating conditions. In HCCI, combustion characteristics and exhaust emissions depend on conditions of air/fuel mixture and chemical reactions of fuel molecules. The fuel design approach is achieved by mixing two components which differ in properties such as density, viscosity, volatility, ignitability and so on. We plan to apply the fuel design approach to HCCI combustion generated in a real engine, and examine the possibility of mixture formation control using the flash boiling spray. Spray characteristics of two component fuel with a flash boiling phenomenon was investigated using Shlieren and Mie scattering photography. Test fuel was injected into a constant volume vessel at ambient conditions imitated injection timing BTDC of a real engine. As a result, it was found that a flash boiling phenomenon greatly changed spray structure, especially in the conditions of lower temperature and density. Therefore, availability of mixture formation control using flash boiling spray was suggested.

• Coupled systems mechanics
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• 제7권1호
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• pp.95-109
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• 2018

The relevance of turbulent mixing in estuarine numerical models for stratified two-layer shallow water flows is analysed in this paper. A one-dimensional numerical model was developed for this purpose by extending an immiscible two-layer model with an additional source term, which accounts for turbulent mixing effects, namely the entrainment of fluid from the lower to the upper layer. The entrainment rate is quantified by an empirical equation as a function of the bulk Richardson number. A finite volume method based on an approximated Roe solver was used to solve the governing coupled system of partial differential equations. A comparison of numerical results with and without entrainment is presented to illustrate the influence of entrainment on both the salt-water intrusion length and lower layer dynamics. Furthermore, one example is given to demonstrate how entrainment terms may help to stabilize the numerical scheme and prevent a possible loss of hyperbolicity. Finally, the model with entrainment is validated by comparing the numerical results to field measurements.

• 대한기계학회논문집A
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• 제32권11호
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• pp.970-977
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• 2008

This paper deals with the dynamic characteristics of the shaft with impeller model which is the most important part in developing the resin mixing machine. Through reverse engineering, it is possible to make the shaft with impeller geometry model which is necessary vibration characteristic analysis by commercial impeller. The natural frequency analysis and structural analysis using finite element analysis software are performed on the imported commercial shaft with impeller model. The most important fundamental natural frequency of the shaft with impeller model is around 14.5 Hz, which well agrees with modal testing. The most effective design variables were extracted by ANOM(analysis of means) and pareto chart. This paper presents approximation 2nd order polynomial as design variables using RSM(response surface methodology). Generally, RSM take 2 or 3 design variables, but this method uses 5 design variables with table of mixed orthogonal array. Further more, the analyzed result of the commercial shaft with impeller is to be utilized for the structural design of resin chock mixing machine.

• 한국도로학회논문집
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• 제15권6호
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• pp.69-78
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• 2013

PURPOSES : In this study blast furnace slag, an industrial byproduct, was used with an activating chemicals, $Ca(OH)_2$ and $Na_2SiO_3$ for carbon capture and sequestration as well as strength development. METHODS : This paper presents the optimized mixing design of Carbon-Capturing and Sequestering Activated Blast-Furnace Slag Mortar. Design of experiments in order to the optimized mixing design was applied and commercial program (MINITAB) was used. Statistical analysis was used to Box-Behnken (B-B) method in response surface analysis. RESULTS : The influencing factors of experimental are water ratio, Chemical admixture ratio and Curing temperature. In the results of response surface analysis, to obtain goal performance, the optimized mixing design for Carbon-Capturing and Sequestering Activated Blast-Furnace Slag Mortar were water ratio 40%, Chemical admixture ratio 58.78% and Curing temperature of $60^{\circ}C$. CONCLUSIONS : Compared with previous studies of this experiment is to some extent the optimal combination is expected to be reliable.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.205-209
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• 2004

인젝터의 배열과 형상 변화는 연소실내에서의 미립화, 증발, 혼합, 화학반응 등을 변화시킴으로써 액체로켓엔진의 연소 조건과 열 교환에 영향을 준다. 본 논문에서는 연소실내의 다양한 현상 중 인젝터 배열이 혼합비 분포에 미치는 영향을 물리적 접근방법을 통하여 살펴보고 프로그램을 작성하여 혼합비 분포를 계산 하고자 하였다. 단, 예측 방법의 유도 과정에서 도입된 물리 현상의 단순화와 여러 가정으로 인해 본 방법의 적용성과 정확성에는 한계가 있으나 mechanical patternator 사용이 어려운 full scale 가스발생기나 연소기의 국부적인 혼합비 예측에 효과적인 활용이 될 수 있으리라 판단된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.378-385
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• 2012

벤트 혼합기는 혼합기 후류에 존재하는 재순환 영역으로 공기를 유입시켜 연료-공기 혼합을 증대시키는 혼합기이다. Stereoscopic PIV기법을 통해 얻은 3차원 속도, 와류, 난류운동에너지를 토대로 계단형 혼합기를 기본 모델로 하여 벤트 혼합기의 성능을 분석하였다. 벤트 혼합기는 두터운 전단층으로 인해 높은 침투거리를 보였으며, 난류운동에너지는 주로 주유동과 제트유동의 경계면을 따라 분포하였다. 이 난류 영역은 혼합영역 내에서 활발히 물질전달을 일으키며, 혼합 증대를 가져온다.