• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
• /
• pp.189-194
• /
• 2000

The optimum mix proportioning of concrete is to produce a concrete which satisfies the strength, workability and durability required with minimum component of materials. However in practice the cement content of mix proportioning in construction field is normally higher then required. In this study, the existing mix proportioning of concrete currently used in Korea Highway Corporation has been reviewed by reducing 10kg of cement content by 3~5 strength in strength and workability during the first year of this project. The optimum mix design is established based on the results of the above review and durability were examined during the second year. The experimental results though 2 year show that 103~0% of the reduction of cement content still satisfies the specified strength of concrete and produces higher durability concrete.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
• /
• pp.645-650
• /
• 2003

The purpose of this study is to provide the optimum mix design of cold weather concrete to be placed at the foundation structures in substation. The basic performance tests including slump and slump flow, air content, compressive strength and freezing & thawing resistance were conducted for cold weather concrete by varying with W/C ratios such as 40%, 50% and 60% and air contents such as 3%, 4%, 5% and 6%. The effect on durability of concrete corresponding to the increasing amount of air content and W/C ratio was evaluated and the optimum mix design was recommended. From this study, the concrete mix design containing 6% of air content and 45% of W/C ratio is recommended for the foundation concrete of substation.

• 한국식생활문화학회지
• /
• 제9권2호
• /
• pp.143-148
• /
• 1994

'Nochi' is one of Korean traditional panfried rice cakes made from glutinous rice or millet and malt. The optimum conditions for the preparation of 'Nochi' were investigated. The ${\alpha}-amylase$ activity of malt was 62.5 units/g dry malt and ${\beta}-amylase$ 1.43 units/g dry malt. Reducing sugar content of 'Nochi' increased with the content of malt and saccharifying time. Both the hardness and cohesiveness of 'Nochi', measured by rheometer, were decreased with increasing the content of malt, while adhesiveness and hardness increased with saccharifying time, but cohesiveness decreased. The optimum conditions for the preparation of 'Nochi' were 8.0%(w/w) of malt and 1 hour 45 minutes of saccharifying time.

• 한국건축시공학회지
• /
• 제3권3호
• /
• pp.91-97
• /
• 2003

At present, the antiwashout underwater concretes are used as popular construction materials in European countries, the United States and Japan. The water-soluble polymers in the antiwashout underwater concretes provide excellent segregation or washout resistance, self-compaction and self-leveling property to the concretes. The purpose of this study is to recommend to optimum mix proportions of antiwashout underwater concretes according to compressive strength of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$. The antiwashout underwater concretes are prepared with various unit cement content, unit water content, sand-aggregate ratio, unit antiwashout agent and superplasticizer content. And they are tested for flowability, and compressive strength. From the test results, it is possible to recommend the optimum mix proportions of antiwashout underwater concretes according to compressive strengths within the range of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$.

• 생물환경조절학회지
• /
• 제22권1호
• /
• pp.55-59
• /
• 2013

본 연구는 레몬과즙의 헤스페리딘 함량이 가장 많은 수확시기 지표를 결정하기 위해 수관내부 및 외부에 착과된 과실에 대해 시기별 헤스페리딘 함량을 착색시기 및 과중과 연관시켜 평가했다. 그 함량은 과실생장에 따라 달랐으며 수관내부 및 외부에 있어 착색이 막 시작되는 개화 후 162일과 176일째에 가장 많았다. 그리고 수관외부가 내부보다 많았다. 이상의 결과는 레몬과실의 헤스페리딘 함량이 가장 많은 적정 수확 시기는 착색이 막 시작이 되고 과실의 생장이 멈추기 직전이라는 것을 나타냈다.

• 한국건설순환자원학회논문집
• /
• 제5권1호
• /
• pp.37-44
• /
• 2017

레드머드는 보오크사이트 원광석에서 생산되는 알루미나의 선광과정에서 발생되는 무기질 부산물이다. 레드머드를 활용하고자하는 연구가 국내에서 이루어지고 있다. 강알칼리성의 레드머드를 건설산업용 촉진제로서 활용하고자 하는 연구로서 알칼리활성화 슬래그-레드머드 시멘트가 국내외적으로 발표되고 있다. 본 논문은 레드머드 대체율에 따른 알칼리활성화 슬래그-레드머드 건식 흙포장재의 최적함수율, 압축강도, 흡수율, 백화발생 특성에 대하여 비교 검토하였다. 그 결과 레드머드 대체율이 증가할수록 알칼리활성화 슬래그-레드머드 흙포장재의 최적 함수비, 흡수율, 백화면적은 증가하고 압축강도는 감소하였다.

• Applied Biological Chemistry
• /
• 제28권3호
• /
• pp.115-123
• /
• 1985

보리의 건식제분공정을 확립키 위하여 수분함량 별 보리의 제분특성을 Brabender Grain Hardness Tester를 사용하여 조사하였다. 분말의 입자크기 별 적정 GHT간극은 -10+12mesh는 $1/0{\sim}1/10$, -12+18mesh는 $0/5{\sim}0/15$, -18mesh는 0/-15이었다. 수분함량에 따른 파쇄성은 수분함량이 감소할수록 증가하였으며 곡립경도는 반대양상을 나타내었다. 제분에 소요되는 에너지는 GHT간극이 작을수록, 수분함량이 증가할수록 큰값을 보였고 수분함량 14.04%에서 최대치를 나타내었다. 건조 소요에너지를 감안할 때 보리의 최적 건식제분조건은 수분함량 12.80%에서 GHT간극 0/-5일 때이었고 이때 1,000kg의 -18mesh 입자를 생산하는데 소요되는 에너지는 92.41kwh이었다.

• 한국산업보건학회지
• /
• 제19권1호
• /
• pp.1-7
• /
• 2009

To establish the Fourier-Transform Infra-Red spectrophotometry(FTIR) Direct-On-Filter(DOF) technique as a useful analytical method for quartz in respirable dust samples, an influence of the kaolinite should be corrected. Respirable dust, created in a dust chamber containing the standard material of quartz and kaolinite were collected using a cyclone equipped with a 25 mm, $0.8\;{\mu}m$ pore size DM filter as a collection medium. This study was designed to compare three methods of correction for kaolinite when quantifying the content of quartz, including the least square, the optimum choice and the spectral subtraction methods. The content of quartz in the respirable dust samples was overestimated by 6.2% when mixed with kaolinite(35.5% by weight). The content of quartz containing kaolinite(72.8% by weight) were overestimated by 32%. The spectral subtraction method underestimated the quartz content by 1.5%, while the other two correction methods, the optimum choice and the least square method, overestimated the quartz content by 1.9% to 6.4% and 0.04 to 1.1%, respectively. The results of this study are suggested that, when correcting for effects of kaolinite on quantitative analysis of quartz in respirable dust by FTIR direct-on-filter method, the least square method produce the most unbiased results be compared with those of other correction methods.

• 콘크리트학회지
• /
• 제6권6호
• /
• pp.135-142
• /
• 1994

본 연구는 고유동성, 고강도 및 고내구성을 가진 고성능 콘크리트를 실용화시키기 위하여 국내에서 시판되고 있는 9종류의 고성능 감수제를 사용한 콘크리트의 품질 특성을 평가하였다. 이를 위하여 혼화제 첨가량에 따라서 굳지 않은 콘크리트의 슬럼프, 공기걍, 단위중량 및 감수율과 경화콘크리트의 압축강도비를 비교분석하였다. 본 시험결과, 국내 시판되는 고성능 감수제를 사용한 콘크리트의 공기연행 효과는 거의 없었으며 또한, 보통강도 및 고성능 콘크리트 각각에 대하여 최적혼화제 첨가량이 존재함을 알아냈다.

• 한국농공학회지
• /
• 제39권6호
• /
• pp.99-110
• /
• 1997

The study was conducted in order to investigate the basic geotechnical properties of sand-bentonite mixtures with the various bentonite contents. The results obtained are as follows : 1. Optimum moisture content of sand-bentonite mixtures was approximately 17.10~18.52% corresponding to the maximum dry density of 1.58~1 .64gf/$cm^3$. As the bentonite contents and curing peroid increased, both the maximum dry density and optimum moisture content of sand-bentonite mixtures increased. 2. The unconfined compressive strength of sand-bentonite mixtures increased as the increase of bentonite content, but it did not change along the curing period. 3. The sand-bentonite mixtures ruptured at 8~15% of the axial strain and the maxi-mum shearing stress was about O.7Okgf/$cm^2$. 4. According to the increase of bentonite content, the cohesion intercept and internal friction of the sand-bentonite mixtures increased slightly in the shear test, while the cohesion intercept increased largely, and the internal friction angle decreased largely in the triaxial test. 5. Both the initial void ratio and swelling of the sand-bentonite mixtures were very low with respect to the consolidation pressure increase. 6. The swelling and shrinkage of sand-bentonite mixtures increased slightly according to the increment of bentonite content.