• 콘크리트학회논문집
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• 제14권1호
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• pp.118-125
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• 2002

콘크리트는 수화과정을 통하여 재료가 성숙되고, 경화된다. 수화의 진행은 엄밀한 의미에서 재령에 의하지 않고 수화도에 의해 제어되므로, 경화가 진행되는 콘크리트의 모든 재료특성과 미세구조 형성과정은 수화도에 의해 정식화되는 것이 바람직하다. 기존 연구는 주로 양생온도가 수화발열속도에 미치는 영향을 고려한 반응함수 개념을 주로 사용하였고, 또한 내부 수분상태의 영향을 습도함수의 형태로 고려한 연구결과는 실제 수화기구를 반영하지 못하고 단지 각 연구자의 실험조건과 배합조건에만 부합하는 결과를 보인다. 따라서 본 연구는 기존 제안식의 단점을 보완하기 위하여 수화기구와 미세구조 형성 과정에 기초하여 반응속도함수를 모델링하였다. 수화반응속도는 온도 및 수분상태에 따라 변화하므로, 본 연구에서는 수화발열 속도에 영향을 미치는 인자로, 시멘트 종류, 물-시멘트비 등의 배합특성과 양생온도 빛 세공조직의 내부수분상태를 고려하였다. 똔 연구에서 제시한 콘크리트의 수화도 예측모델은 기존의 온도영향만을 주로 고려하는 반응속도함수를 콘크리트내부의 수분분포 상태를 고려하여 모델을 개선하였으며, 이는 실제 측정한 수화도에 매우 근접하여 그 유용성을 검증하였다. 또한 수화도의 정의와 제시한 모델을 이용하여 콘크리트 요소내의 온도, 습도 덴 수화도를 수치적으로 결정하여 단열온도상승곡선을 정확히 모사 할 수 있었다. 제안된 모델은 수화가 진행되는 콘크리트의 여러 역학적 특성 및 미세구조 형성과정을 적절히 표현하고, 수화과정이 온도 및 습도상태를 결정하는 초기재령 콘크리트의 단면 내 온 습도상태를 추정하여 궁극적으로 초기재령 콘크리트의 균열 위험성을 평가하는데 유용하게 이용될 수 있을 것으로 사료된다.

• 한국농공학회논문집
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• 제57권1호
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• pp.79-87
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• 2015

A thermochemical equilibrium model was constructed for predicting composition of synthesis gas in biomass gasification. The model included estimation of equilibrium constants using Gibbs free energy. After constructing the model, the results were compared with the experimental values and predictions from a previous model. Gas compositions were reasonably well agreed with them and showed effects of operational and fuel condition. When the reaction temperature increased, the lower heating values decreased due to the decrease in CH4 concentrations. The methane concentrations were lower than those observed in experimental results. The model was used to predict the gas composition and heating values for the cases of mixed fuel of charcoal and un-dry woodchips. Although downdraft gasifiers require fuels less than 15% of moisture contents, the model results indicated that the mixed fuel with charcoal and woodchips which had over 25% of moisture contents could be used in the downdraft gasifiers. It might be explained by increase in energy density resulting from mixing charcoal. The results imply that the efforts and costs for drying biomass fuels could be reduced by mixing charcoal or fuels with higher calorific values.

• Journal of the Korean Wood Science and Technology
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• 제35권4호
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• pp.1-8
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• 2007

목재의 방향별 내부수분이동계수와 표면방사계수를 측정하기 위하여 2.5 (방사방향) ${\times}$ 2.5 (접선방향) ${\times}$ 2.5cm (섬유방향)의 낙엽송 정육면체 시편을 제작하였다. 수분이동방향과 직교하는 단면을 제외한 나머지 4면을 파라핀테이프와 고무테이프를 이용하여 코팅한 후, 70, 50, $30^{\circ}C$의 3가지 온도조건과 30, 60%의 2가지 상대습도 조건에서 건조시키면서, 목재 내부와 표면에서의 수분이동을 평가하였다. 자유수 유동과 결합수 및 수증기의 확산에 의한 내부수분이동계수는 고온조건에서 크게 나타났으며, 섬유방향이 횡단방향에 비하여 6배, 횡단방향에서는 방사방향이 접선방향에 비하여 1.2배 정도 큰 값을 보였다. 표면방사계수는 온도가 상승하고, 표면함수율이 감소함에 따라 증가하였다. 본 연구 결과를 이용하여 비평형상태에서 낙엽송재 내 함수율 분포변화와 증발수분량을 예측할 수 있으리라 기대된다.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.218-218
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• 2003

Recently we showed the prototype portable device for the determination of human skin moisture by using near infrared spectroscopy. In order to optimize the acquiring condition of NIR spectrum of skin and control the target information of water depending the site such as epidermis and dermis, skin depth profiling was investigated changing the distance between illuminations and receiving of radiation in the terminal of fiber probe. The colleted light information could be controlled by changing the distance of the fiber optic probes. It was confirmed that the longer distance we used, the deeper site from the skin surface we could get information from in this study. Four kinds of probes with distances such as 0.03 mm, 0.1 mm, 0.5 mm, and 1.0 mm were used. In addition, the gap size from 0.3 mm to 3.0 mm was studied to control the intensity of water absorbance effectively and to avoid saturation of water absorption. We also investigated the reference materials depending the reflectance ratio for water absorption not to be saturated because of the strong absorptivity of water. Furthermore, spectroscopic information regarding free water and bound water around 1850 nm was investigated by using the different distance of fiber optic probes. This study would be great help to control the spectroscopic information of water to be measured depending the site where water exists.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
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• pp.422-427
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• 2008

The major cause of Concrete Spalling at high temperatures can be divided into the Vapor Pressure Rising, caused by the increase in free water temperature within the concrete, and Pore Pressure Rising induced by the vapor moving into dense pores within the concrete. Although the occurrence of spalling within concrete caused by these pressure increases can be assessed experimentally, a close examination into Mechanistic influence against various spalling factors shall be carried out first by using Mathematical Modeling and Theoretical Equations. The Spalling Prospect Process by theoretical mechanism is expedited in order of the following; selection of heating condition (fire strength and flame heating direction), a selection of constituent elements, an analysis of heat transmission, an analysis of moisture movement, distribution of water content, an analysis of pore/vapor pressure, and assessment of spalling occurrence.

• 농업과학연구
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• 제48권3호
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• pp.535-544
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• 2021

When baking, the proper blending or mixing of materials will affect the quality of the product. The mixing strength is important when establishing the optimal conditions for batter, and control of the mixing condition is accordingly an important factor. This study investigated the effects of the mixing speed and time on the quality characteristics of a gluten-free type of rice batter. The batter samples manufactured for this purpose are as follows: control (+) (wheat flour), control (-) (rice flour), T1 (1,800 rpm, 1 min), T2 (1,800 rpm, 2 min), T3 (1,800 rpm, 3 min), T4 (3,600 rpm, 1 min), T5 (3,600 rpm, 2 min), T6 (3,600 rpm, 3 min). In this study, rice flour was used in the T1 to T6 samples. The pH of the batter tended to be higher when the mixing speed was slower and the time was shorter depending on the ultra-high mixing conditions. The moisture content of T3 was highest, and there was no difference according to the ultra-high speed conditions. The specific volumes of the ultra-high mixing treatments were higher than those of the control samples. The relationship between the specific volume, hardness and springiness of rice bread according to the mixing speed and time was weak. Therefore, it is considered that the application of ultra-high speeds when manufacturing gluten-free batter can have a positive effect on improving the production efficiency by reducing the processing time.

• Smart Structures and Systems
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• 제20권3호
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• pp.369-383
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• 2017

In this work, the effects of moisture and temperature on free vibration characteristics of functionally graded (FG) nanobeams resting on elastic foundation is studied by proposing a novel simple trigonometric shear deformation theory. The main advantage of this theory is that, in addition to including the shear deformation influence, the displacement field is modeled with only 2 unknowns as the case of the classical beam theory (CBT) and which is even less than the Timoshenko beam theory (TBT). Three types of environmental condition namely uniform, linear, and sinusoidal hygrothermal loading are studied. Material properties of FG beams are assumed to vary according to a power law distribution of the volume fraction of the constituents. Equations of motion are derived from Hamilton's principle. Numerical examples are presented to show the validity and accuracy of present shear deformation theories. The effects of hygro-thermal environments, power law index, nonlocality and elastic foundation on the free vibration responses of FG beams under hygro-thermal effect are investigated.

• 생물환경조절학회지
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• 제15권1호
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• pp.107-113
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• 2006

These studies were carried out to investigate the quality of green tea processed by different pan-firing hand rolling and to select the best conditions during the procedure of green tea processing the results were as follows. At harvestion tea plant leaf, tea plants had 4 leaves. each leaf size was 7.5 cm'$\square$2.6 cm, and weight of 100 buds 46.6 g. The increase of pan-fired time decreased in the moisture content and yield of green tea. After processing green tea, 5 times pan-fired one had much more contents of total nitrogen (T-N:5.31%), caffeine (2.00%) and total amino acid (T.A.A. : 3,046 mg%) and less content of tannin (13.41%) than the other treatments. but 3 times pan-fired one had the highest contents of vitamin C (204.3 mg%) and chlorophyll (365.0 mg%) among three kinds pan-firing method. Sixteen kinds of free amino acid including theanine as a good taste component of pan-fired green tea were isolated and measured by HPLC. Free amino acid (FAA) contents were in the range of $2,683{\sim}2,925$ mg% and among various pan-firing methods, 5 tims pan-fired one had the highest content of F.A.A. Among these free amino acids, theanine occupied as much as $56.4{\sim}61.3%$ of F.A.A. Lightness, yellowness and redness of 5 times pan-fired green tea were middle value among three different treatments. Besides, it gained the highest score of sensory evaluation among them. These above results suggested that 5 times pan-fired green tea was considered to be the best level as pan-firing times of green tea processing.

• 한국식품영양학회지
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• 제9권4호
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• pp.438-440
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• 1996

인공재배한 백복령의 성분을 분석한 결과 일반성분은 수분 58%, 회분 1.8%, 지방 0.9%, 단백질 0.6% 섬유소 0.3%로 나타났으며 재배장소와 방법, 수확시기, 건조조건에 따라 차이가 난다. 부기성분은 ICP로 측정한 결과 Zn 0.63mg%, Cu 0.18mg%, Fe 1.56mg%, Mn 1.62mg%, Mg 5.28mg%, Ca 12.59mg%, Na 10.12mg%, K 52.39mg%로 나타나 K, Ca, Na 등의 양이온 무기성분이 상당량 함유되어 있었다. 복령 물추출물의 유리당은 glucose만 검출되었고 함량은 1.16mg%였다. 아미노산은 구성아미노산 13종, 유리아미노산 9종이 확인되었고 함량은 각각 1247.17mg%, 174.44mg%였으며, Phe, Iso, Leu, Tyr, His 함량이 높게 나타났다.

• 한국식품조리과학회지
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• 제28권2호
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• pp.195-206
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• 2012

The purpose of this study was to determined the optimal mixing condition of two different amounts of tomato powder (A), and starch (B) for the preparation of sausage prepared with tomato powder was determined. The content of lycopene was 3 mg/g. The experiment was designed according to the central composite design of response surface, which showed 10 experimental points including 2 replicates for tomato powder and starch. The physiochemical, mechanical, antioxidant activity and sensory characteristics of samples were measured. The results of the physiochemical, mechanical and antioxidant activity analysis of each sample, including pH, moisture content, color L, color a, color b, hardness, chewiness and cohesiveness, total phenolic content and DPPH free radical scavenging activity showed significant differences. The sensory measurements were significantly different in color, flavor, chewiness, overall quality. The optimum formulation, which was calculated using the numerical and graphical method, was determined to be 4.26 g tomato powder and 7.51 g starch.