• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.97-102
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• 2003

Experimental investigations were carried out in an atmospheric pressure, optically accessible and laboratory-scale dump combustor operating on natural gas. The objective of this study is to obtain the phase-resolved gas temperatures at different phases of the oscillating pressure cycle during unstable combustion. CARS temperature measurements were made at several spatial locations under lean premixed conditions to get the information on temperature field within the combustor. Also the effect of incomplete fuel-air mixing on phase-resolved temperature fluctuation was investigated. Results including phase-resolved averaged temperature, normalized standard deviation and temperature probability distribution functions (PDFs) were provided in this paper. Temperature PDFs give an insight on the flame behavior. And strong correlation between phase-resolved temperature profile and pressure cycle was observed. Results of the phase-resolved high temperature give an additional information on the perturbation of equivalence ratio at flame as well as the effect of mixing quality on NOx emission characteristics.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.85-88
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• 2007

A number of R, G and B LEDs for reference color temperature mixing ratio of RGB was determined by the theory of RGB mixing as a baseline. Once the number of LEDs was determined the objective color temperature from baseline has been achieved by the control the RGB duty ratio. And a practical prototype of 50W floodlighting adjusted by the above algorithm. The micro controller was developed with control algorithm for RGB duty ratio to obtain the objective color temperature. Detailed experiments to optimize algorithm of duty ratio and color temperature will be discussed in this paper as well.

• 한국산업융합학회 논문집
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• 제19권2호
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• pp.95-100
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• 2016

This study proposes the temperature compensation algorithm using thermopile detector for non-dispersive infrared Nitrogen gas sensor. From the output voltage of thermistor that is attached onto the infrared detector, the ambient temperature was extracted. The effects of temperatures on the properties of sensor module characteristics of narrow bandpass filter, optical cavity and infrared lamp, and air mixing gas have been introduced in order to implement the temperature compensation algorithm.

• Computers and Concrete
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• 제6권4호
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• pp.343-356
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• 2009

Experiments were designed to investigate the flow behavior of portland cement paste and concrete incorporating superplasticizers. The paste and concrete mixtures were subjected to prolonged mixing for up to 110 min at high temperature. The yield stress values of concrete and that of the corresponding cement paste were measured using a rotating rheometer and viscometer, respectively. The results reveal a weak linear correlation between the yield stress of concrete mixtures and that of the corresponding cement pastes. Results also indicate that the yield stress of concrete varies in a linear fashion with the elapsed time, while its variations with the temperature and superplasticizer dosage follow power and inverse power functions, respectively. In this study, the genetic algorithms (GA) technique was used to predict the yield stress of concrete considering various parameters, such as the mixing time, ambient temperature, and superplasticizer dosage. A sensitivity study was conducted to evaluate the ability of the GA equations thus developed to capture the effects of test parameters on the yield stress of concrete. It was found that the GA equations were sensitive to the effects of test parameters and provided yield stress predictions that compared well with corresponding experimental data.

• 한국농공학회지
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• 제26권1호
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• pp.52-72
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• 1984

This study was performed to obtain the basic data which can be applied to the use of epoxy resin mortars. The data was based on the properties of epoxy resin mortars depending upon various mixing ratios to compare those of cement mortar. The resin which was used at this experiment was Epi-Bis type epoxy resin which is extensively being used as concrete structures. In the case of epoxy resin mortar, mixing ratios of resin to fine aggregate were 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1 :12 and 1:14, but the ratio of cement to fine aggregate in cement mortar was 1 : 2.5. The results obtained are summarized as follows; 1.When the mixing ratio was 1: 6, the highest density was 2.01 g/cm$^3$, being lower than 2.13 g/cm$^3$ of that of cement mortar. 2.According to the water absorption and water permeability test, the watertightness was shown very high at the mixing ratios of 1: 2, 1: 4 and 1: 6. But then the mixing ratio was less than 1 : 6, the watertightness considerably decreased. By this result, it was regarded that optimum mixing ratio of epoxy resin mortar for watertight structures should be richer mixing ratio than 1: 6. 3.The hardening shrinkage was large as the mixing ratio became leaner, but the values were remarkably small as compared with cement mortar. And the influence of dryness and moisture was exerted little at richer mixing ratio than 1: 6, but its effect was obvious at the lean mixing ratio, 1: 8, 1:10,1:12 and 1:14. It was confirmed that the optimum mixing ratio for concrete structures which would be influenced by the repeated dryness and moisture should be rich mixing ratio higher than 1: 6. 4.The compressive, bending and splitting tensile strenghs were observed very high, even the value at the mixing ratio of 1:14 was higher than that of cement mortar. It showed that epoxy resin mortar especially was to have high strength in bending and splitting tensile strength. Also, the initial strength within 24 hours gave rise to high value. Thus it was clear that epoxy resin was rapid hardening material. The multiple regression equations of strength were computed depending on a function of mixing ratios and curing times. 5.The elastic moduli derived from the compressive stress-strain curve were slightly smaller than the value of cement mortar, and the toughness of epoxy resin mortar was larger than that of cement mortar. 6.The impact resistance was strong compared with cement mortar at all mixing ratios. Especially, bending impact strength by the square pillar specimens was higher than the impact resistance of flat specimens or cylinderic specimens. 7.The Brinell hardness was relatively larger than that of cement mortar, but it gradually decreased with the decline of mixing ratio, and Brinell hardness at mixing ratio of 1 :14 was much the same as cement mortar. 8.The abrasion rate of epoxy resin mortar at all mixing ratio, when Losangeles abation testing machine revolved 500 times, was very low. Even mixing ratio of 1 :14 was no more than 31.41%, which was less than critical abrasion rate 40% of coarse aggregate for cement concrete. Consequently, the abrasion rate of epoxy resin mortar was superior to cement mortar, and the relation between abrasion rate and Brinell hardness was highly significant as exponential curve. 9.The highest bond strength of epoxy resin mortar was 12.9 kg/cm$^2$ at the mixing ratio of 1:2. The failure of bonded flat steel specimens occurred on the part of epoxy resin mortar at the mixing ratio of 1: 2 and 1: 4, and that of bonded cement concrete specimens was fond on the part of combained concrete at the mixing ratio of 1 : 2 ,1: 4 and 1: 6. It was confirmed that the optimum mixing ratio for bonding of steel plate, and of cement concrete should be rich mixing ratio above 1 : 4 and 1 : 6 respectively. 10.The variations of color tone by heating began to take place at about 60˚C, and the ultimate change occurred at 120˚C. The compressive, bending and splitting tensile strengths increased with rising temperature up to 80˚ C, but these rapidly decreased when temperature was above 800 C. Accordingly, it was evident that the resistance temperature of epoxy resin mortar was about 80˚C which was generally considered lower than that of the other concrete materials. But it is likely that there is no problem in epoxy resin mortar when used for unnecessary materials of high temperature resistance. The multiple regression equations of strength were computed depending on a function of mixing ratios and heating temperatures. 11.The susceptibility to chemical attack of cement mortar was easily affected by inorganic and organic acid. and that of epoxy resin mortar with mixing ratio of 1: 4 was of great resistance. On the other hand, when mixing ratio was lower than 1 : 8 epoxy resin mortar had very poor resistance, especially being poor resistant to organicacid. Therefore, for the structures requiring chemical resistance optimum mixing of epoxy resin mortar should be rich mixing ratio higher than 1: 4.

• 한국해양학회지:바다
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• 제18권3호
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• pp.111-121
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• 2013

지역규모의 정확한 일기예보와 해양생태계 변화 이해에 있어서 수온 예측은 매우 중요하다. 황해는 조류가 매우 빠르고 탁도가 높다. 이러한 해역에서는 수치 모델의 수직 혼합 기법 및 해수의 탁도에 따른 수형(water type)이 수온 구조 결정에 많은 영향을 미친다. 수직 혼합 기법 변화와 탁도의 변화에 따른 황해 수온 모사의 민감도를 알아보기 위해 3차원 해양 순환 모델인 Regional Ocean Modeling System (ROMS)을 사용하여 수치 실험을 수행하였다. 수직 혼합 기법은 해양 순환 모델에서 많이 사용되는 Mellor-Yamada level 2.5 closure(M-Y)와 K-Profile parameterization (KPP)을 사용하고, 탁도는 Jerlov의 분류에 따른 수형 1, 3, 5를 사용하여 수치 실험을 수행하고 그 결과를 국립수산과학원에서 제공하는 정선 해양 관측 자료와 비교, 분석하였다. M-Y 기법은 수직적 혼합을 상대적으로 강하게 모의하였으며 그 결과로 저층수온이 높게 형성되었다. 높은 저층 수온은 탁도를 높게 설정하면 완화되지만 표층 수온이 높아지는 단점이 있다. KPP 기법은 M-Y 기법보다는 수직 혼합을 약하게 모의하고 이 약한 수직 혼합 때문에 황해 연안을 따라 형성되는 조석전선을 잘 재현하지 못하였으나, 저층 수온은 관측 수온에 더 가깝게 재현하였다. 결과적으로 황해 3차원 해양순환 모델실험에서 M-Y 기법은 수직 혼합이 잘 되어 표층과 저층의 수온 차이가 작게 나타나고, KPP 기법은 이와 반대로 모의하였다. 탁도의 영향을 표현하는 Jerlov 수형은 높을수록 일사량이 낮은 수심까지만 투과되어 성층을 잘 표현하였고, 낮을수록 깊은 수심까지 일사량이 투과되어 표층과 저층의 수온차를 작게 모의하였다.

• 한국환경과학회지
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• 제6권6호
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• pp.579-588
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• 1997

In order to see the stratification related to the heat flux In Deukryang Bay, the oceanographic data on July 12, 1994 and the meteorological data of Kohung and Kwangju meteorological stations were analysed. The temperature durerences between the sea surface and the near bottom were 1~3 ton spring tide (July 12, 1994) In Deukryang Bay. The temperature anomalies were high about 3t during summer In 1994. These mean that the non mixing was not effective In destroying the stratification due to the sea surface heating by the solar radition, even though it was on spring tide. The maximum solar radiation was about 600 ly/day, which was the value of the same date of oceanographic observation. The sensible and the latent heat flux which are 0~100 ly/day were not so varied during summer. The absorbed heat flux through the sea surface was mostly lost by the back radiation. which ranges are about 0~-400 ly/day. The dimensionless mixing parameter related to the buoyancy flux was 5~150$\times$$10^{-5}$. The efficiency of tidal mixing to destroy the stratecation was 0.4~0.6%.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.157-163
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• 2002

Using the CFD method, we investigated the combustion characteristics of grate-rotary kiln incinerator through the residence time, path line of flow and distributions of temperature and CO mass fraction according to the shape of mixing chamber and the existence and nonexistence of baffle at the exit of bypass duct. The results show that the now mixing and residence time could be variable according to the shape of mixing chamber and baffle, and we could know the temperature in the mixing chamber could increase too high if the combustion process on the grate retarded.

• 소성∙가공
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• 제18권5호
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• pp.401-409
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• 2009

The change of the thermal properties of exothermic and insulating materials with the mixing condition of raw materials which is the most important factor for exothermic & insulating materials was investigated by using the evaluation system of the thermal properties of exothermic and insulating materials. In this study, the effect of the thermal properties of the exothermic & insulating materials such as exothermic properties, endothermic properties, insulating properties, maximum temperature of molten metal, ignition time of exothermic & insulating materials and temperature recovery time on the mixing ratio of reductant and oxidant, types of reductant, and particle sizes of reductants was examined. It could be expected to design the mixing condition of raw materials for various exothermic and insulating materials.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.118-126
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• 2009

The change of the thermal properties of exothermic & insulating materials with mixing condition of raw materials which is the most important factor for exothermic & insulating materials was investigated by using the evaluation system of the thermal properties of exothermic & insulating materials. In this study, the effect of the thermal properties of the exothermic & insulating materials such as exothermic properties, endothermic properties, insulating properties, maximum temperature of molten metal, ignition time of exothermic & insulating materials and temperature recovery time on the mixing ratio of reductant and oxidant, types of reductant, and particle sizes of reductants was examined. It could be expected to design the mixing condition of raw materials for various exothermic & insulating materials.