• 한국건축시공학회지
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• 제18권4호
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• pp.329-335
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• 2018

본 연구의 목적은 기존 콘크리트 건물의 단면확대 내진보강 기술에서 필요한 고유동 고접착성의 보강 모르타르 배합의 개발이다. 보강 모르타르의 목표성능(플로우 220mm 이상, 압축강도 30MPa, 접착강도 1MPa 이상)을 위해 물-결합재비, 잔골재-결합재비, 폴리머-결합재비, 증점제 사용 및 초속경시멘트의 혼입 등을 변수로 단계적으로 배합실험을 수행하였다. 모르타르의 접착강도는 기존 콘크리트의 다양한 면 처리 상태에 따라 평가하였다. 실험결과로부터 단면증설용 보강 모르타르의 배합을 위해 폴리머-결합재비는 10%, 초속경시멘트의 치환율은 5%가 추천될 수 있었는데, 이 배합은 초기 플로우 220 mm, 높은 초기강도 발현, 압축강도 35 MPa 그리고 접착강도 1.2 MPa 이상의 성능을 보였다.

• 한국지역사회생활과학회지
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• 제19권2호
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• pp.213-221
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• 2008

In this study, a dye bath was made using a mixture of distilled water, pine needle extract and bamboo vinegar. Analysis and comparison of various functions of cotton fabrics dyed using bamboo charcoal and gardenia seeds in distilled water and in the dye bath mixture were done. The summary of the results is as follows. Comparing bamboo vinegar and the pine needle extracts, the bamboo vinegar had a higher antibacterial function. In the case of natural dyeing cotton fabrics using bamboo charcoal and gardenia seeds, the additional amount of dyestuff for optimization is 10 g and 20 g respectively per 1 liter of distilled water. The suitable dye bath mixture ratio of distilled water, pine needle extract, and bamboo vinegar considering functionality and economical efficiency of dyed fabrics is 4:3:3. By using the mixture made in this study as a dye bath, improved antibacterial function, deodorization, and colorfastness can be obtained more than distilled water alone.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2020년도 춘계학술대회
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• pp.72-72
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• 2020

Various mixtures were prepared depending on the mixing ratio of Scutellaria baicalensis hot water extract (SB-HW) and Chrysanthemum morifolium ethanol extract (CM-E) and their anti-inflammatory activity were compared. Among them, SB-HW (80 ㎍/mL)/CM-E (120 ㎍/mL) or SB-HW (40 ㎍/mL)/CM-E (160 ㎍/mL) significantly inhibited LPS-stimulated NO and IL-6 levels in RAW 264.7 cells. The SB-HW (80 ㎍/mL)/CM-E (120 ㎍/mL) mixture, which was determined as active mixture, significantly reduced MUC5AC secretion in PMA and LPS-induced NCI-H292 cells. The active mixture also reduced the production of PGE2 and IL-8 in PMA-induced A549 cells. LC-MS/MS analysis showed that the active mixture was composed of high contents of flavone glycosides, such as baicalin and cynaroside. Western blot analysis indicated that the active mixture suppressed phosphorylation of ERK, JNK, and p38, associating with the inhibition of MAPK signaling. Taken together, our results suggest that the active mixture could be applied as a new anti-inflammatory herbal medicine

• 한국태양에너지학회 논문집
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• 제28권5호
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• pp.78-84
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• 2008

Heat pipes are considered to be promising candidates to enhance the heat transport capability of evacuated solar collectors in a wide temperature range. The working fluid must be selected properly considering various operating conditions of heat pipes for medium-high temperature range to avoid dry-out, local overheating, and frozen failure. The advantage of using binary mixture as heat pipe working fluid is that it can extend operating temperature range of the system as it can overcome operating temperature limit of a single fluid. Various operating temperature ranges were imposed in the experiments to simulate the actual operation of solar collectors using water-ethanol binary mixture. Tests were conducted for the coolant temperature range of -10$^{\circ}C$ to 120$^{\circ}C$, and mixing ratio range was from 0 to 1 based on mass fraction.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3311-3316
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• 2007

To analyze the influence of valve overlap period on a backfire occurrence, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and backfire limit equivalence ratio defined as fuel-air ratio equivalence ratio at which backfire occurs is examined according to various valve overlap period. The MCVVT is the system to control valve overlap period by mechanical device. It is estimated that the lower valve overlap period has the higher backfire limit equivalence ratio though the same energy is supplied. When the valve overlap period is changed from 30$^{circ}$ CA to 0$^{circ}$ CA, backfire limit equivalence ratio is increased 74%, approximately. It means that valve overlap period is concern in backfire occurrence, and may be one of the methods for controlling back fire occurred in a $H_2$ engine.

• 설비공학논문집
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• 제23권1호
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• pp.73-79
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• 2011

A portion of oil for lubrication of compressor flows together with refrigerant in the refrigeration system. If the oil discharge from a compressor is increased in the refrigeration system, not only pressure drop is increased in other components, such as evaporator and gas cooler, but also heat transfer coefficient in the heat exchangers is decreased. Oil discharge rate from a compressor may strongly depend on operating conditions of a compressor. In this study, one stage single rotary compressor is employed for measuring oil circulation ratio(OCR). Carbon dioxide and PAG oil are used as refrigerant and lubricant. Using a U-tube densimeter, mixture density is measured. Oil circulation ratio(OCR) can be estimated by measured mixture density. The results obtained indicate that the oil circulation ratio(OCR) is increased as the suction temperature or compressor operating frequency is increased. Oil circulation ratio(OCR) correlation of the compressor is also suggested.

• Geomechanics and Engineering
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• 제1권1호
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• pp.1-15
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• 2009

Many aspects of the behavior of sands are affected by the content of non-plastic fine particles and these various aspects should be included in a constitutive model for the soil behavior. The fines content affects maximum and minimum void ratios, compressibility, shear strength, and static liquefaction under undrained conditions. Twenty-eight undrained triaxial compression tests were performed on mixtures of sand and fine particles with fines contents of 0, 10, 20, 30, 50, 75, and 100% to study the effects of fines on void ratio, compressibility, and the occurrence of static liquefaction. The experiments were performed at low consolidation pressures at which liquefaction may occur in near-surface, natural deposits. The presence of fines creates a particle structure in the soil that is highly compressible, enhancing the potential for liquefaction, and the fines also alter the basic stress-strain and volume change behavior, which should be modeled to predict the occurrence of static liquefaction in the field. The void ratio at which liquefaction occurs for each sand/fines mixture was determined, and the variation of compressibility with void ratio was determined for each mixture. This allowed a relation to be determined between fines content, void ratio, compressibility, and the occurrence of static liquefaction. Such relations may vary from sand to sand, but the present results are believed to indicate the trend in such relations.

• 한국도로학회논문집
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• 제3권1호
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• pp.185-197
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• 2001

본 연구는 온도에 따라 특성이 변하는 아스팔트 콘크리트의 파괴인성을 규명하기 위하여 기존의 유효균열 모델을 수정하는 연구를 다루고 있다. 본래의 ECM모델은 콘크리트와 같은 고체에 적용되도록 개발되어 재료의 포아슨 비를 고려하지 않는다. 하지만 아스팔트 콘크리트는 온도변화에 민감하여 온도에 따라 포아슨 비가 변화하므로 다양한 온도하에서 정확한 파괴 특성을 알기 위해서는 포아슨 비가 고려되어져야 한다. 3개의 개질아스팔트 결합재를 포함한 4가지 결합재를 사용하여 밀입도 아스팔트 혼합물을 제조하여 초기균열 보에 대한 3점 휨 시험을 $-5^{\circ}C$부터 $-35^{\circ}C$까지에서 수행하였다. 탄성계수, 휨강도 및 파괴인성을 시험을 통하여 구하였다. 시험결과 포아슨비가 고려되는 수정 ECM 공식을 사용하므로서 보다 정확한 값들을 얻을 수 있었다. 폴리머 개질 아스팔트 혼합물이 일반아스팔트 혼합물에 비하여 더 낮은 저온하에서 더 높은 강성과 파괴인성을 유지함을 알 수 있었다.

• 농업과학연구
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• 제3권1호
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• pp.53-60
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• 1976

연탄재의 삽목용토(揷木用土)로서의 이용가능성(利用可能性)을 조사(調査)하기 위해 연탄재 모래 및 Vermiculite를 몇가지 비율(比率)로 혼합(混合)한 용토(用土)를 사용하여 삽수(揷穗)의 발근(發根)에 미치는 영향(影響)을 조사(調査)하고 아울러 연탄재를 삽목용토(揷木用土)로 사용할 때 가장 적당한 용토(用土)의 준비방법을 구명(究明)하기 위하여 입자(粒子)의 크기를 몇가지 종류(種類)로 구분(區分)하여 삽수(揷穗)의 발근(發根)에 미치는 영향(影響)을 조사(調査)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 연탄재는 단용(單用)으로도 모래에 비하여 우수한 발근용토(發根用土)로 생각되며 타용토(他用土)와 혼합(混合)해서 사용하면 더욱 효과적(效果的)이다. 2. 연탄재를 삽목용토(揷木用土)로 사용할 경우 입자(粒子)의 크기는 2~3mm의 것이 가장 좋다고 생각된다.

• 한국연소학회지
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• 제13권3호
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• pp.9-16
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• 2008

In this study, a cylindrical constant volume combustion chamber is used to investigate the flow and combustion characteristics of methane-air homogeneous mixture under various initial charge pressure, excess air ratios and ignition times. The flame and burning speed, mean gas speed are calculated by numerical analysis to analyze the combustion characteristics. It is found that the mean gas velocity during combustion has the maximum value around 300 ms and then decreased gradually on the condition of 10000 ms, and that the combustion duration is shorten and flame speed and burning velocity have the highest value under the conditions of an excess air ratio 1.1, an initial charge pressure of 0.2 MPa and an ignition time of 300 ms in the present study. And, the initial pressure and burning speed are in inverse proportion, so that it is in agreement with Strehlow who presented that the initial pressure and burning speed are in inverse proportion when the burning speed is under 50cm/s.