• Asian-Australasian Journal of Animal Sciences
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• 제9권1호
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• pp.91-99
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• 1996

About 7.7 million tons of straw dry matter are being rotten during the monsoon. The objective of this trial was to develop a technique to preserve straw under wet condition. To simulate the moisture content of wet straw, a dry straw was deeped overnight in water. After draining the excess water, the wet straw(668 g moisture $kg^{-1}$) was divided into twenty fractions and preserved with 0, 30, 50 ro 70 g urea $kg^{-1}$ dry matter for either of 30, 60, 90, 120 or 180 days in sealed plastic container. Considering the colour, smell, fungal infestation and pH, the wert straw was preserved excellently up to 180 days when 50 or 70 g of urea per kg DM was used. Urea preservation increased the crude protein contents of straw by 3.6 to 6.4 times (174 to $364g{\cdot}kg^{-1}$) over that of the dry straw ($48g{\cdot}kg^{-1}$). Although the NDF content of straw was not effected by the level of urea or by the length of the preservation period, but the ADF content increased (p > 0.05) by 0.086 to $0.889g{\cdot}kg^{-1}$ straw DM for each g increase in the urea level. At 48 hours, the DM degradability of dry straw was $350g{\cdot}kg^{-1}$, which increased to $633g{\cdot}kg^{-1}$ when preserved with 50 g urea $kg^{-1}$ for 180 days. For the same straw, both the rate(0.0388 vs. 0.0136 fraction $h^{-1}$), the extent(717 vs. $631g{\cdot}kg^{-1}$) of straw degradation and the estimated ME(9.55 vs. $6.51MJ{\cdot}kg^{-1}$ straw DM) were higher in the preserved than the dry straw.

• Composites Research
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• 제30권6호
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• pp.371-378
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• 2017

본 연구에서는 대표적인 열경화성 재료인 에폭시 기지의 흡습탄성 거동을 예측하기 위해 분자동역학 전산모사를수행하였다. 고분자 복합재가 오랜 시간 동안 흡습환경에 지속적으로 노출될 경우, 거시적 물성의 저하가 발생하기 때문에 복합재의 내구설계 측면에 있어 흡습노화 현상에 대해 분자스케일적으로 접근하는 방법은 매우 중요하다. 본 연구에서는 $EPON862^{(R)}$ 수지와 아민계 Triethylenetetramine (TETA) 경화제로 비정질 에폭시 분자모델을 구성하였으며, 각각 30과 90%의 가교 상태에서 수분 흡수 유무에 따른 물성변화를 관찰하였다. 건조상태의 에폭시와 수분이 4 wt% 포함된 에폭시 단위셀에 대한 평형 및 비평형 앙상블 전산모사 과정을 통해, 에폭시의 수분팽창계수, 응력-변형률 선도 및 탄성계수 그리고 침투된 수분의 수지 내 확산계수를 예측하였다. 또한 흡습된 구조와 그에 따른 물성변화의 상관관계를 규명하기 위해, 자유체적 변화 및 흡습에 따른 에폭시 수지의 비결합 포텐셜 에너지 변화를 관찰하였다.

• Steel and Composite Structures
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• 제34권4호
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• pp.511-524
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• 2020

In this research, a simple four-variable trigonometric integral shear deformation model is proposed for the static behavior of advanced functionally graded (AFG) ceramic-metal plates supported by a two-parameter elastic foundation and subjected to a nonlinear hygro-thermo-mechanical load. The elastic properties, including both the thermal expansion and moisture coefficients of the plate, are also supposed to be varied within thickness direction by following a power law distribution in terms of volume fractions of the components of the material. The interest of the current theory is seen in its kinematics that use only four independent unknowns, while first-order plate theory and other higher-order plate theories require at least five unknowns. The "in-plane displacement field" of the proposed theory utilizes cosine functions in terms of thickness coordinates to calculate out-of-plane shear deformations. The vertical displacement includes flexural and shear components. The elastic foundation is introduced in mathematical modeling as a two-parameter Winkler-Pasternak foundation. The virtual displacement principle is applied to obtain the basic equations and a Navier solution technique is used to determine an analytical solution. The numerical results predicted by the proposed formulation are compared with results already published in the literature to demonstrate the accuracy and efficiency of the proposed theory. The influences of "moisture concentration", temperature, stiffness of foundation, shear deformation, geometric ratios and volume fraction variation on the mechanical behavior of AFG plates are examined and discussed in detail.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.153-153
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• 2019

Evapotranspiration (ET) is an important component of hydrological processes. Accurate estimates of ET variation are of vital importance for natural hazard adaptation and water resource management. This study first developed a soil water index (SWI)-based Priestley-Taylor algorithm (SWI-PT) based on the enhanced vegetation index (EVI), SWI, net radiation, and temperature. The algorithm was then compared with a modified satellite-based Priestley-Taylor ET model (MS-PT). After examining the performance of the two models at 10 flux tower sites in different land cover types over East Asia and Australia, the daily estimates from the SWI-PT model were closer to observations than those of the MS-PT model in each land cover type. The average correlation coefficient of the SWI-PT model was 0.81, compared with 0.66 in the original MS-PT model. The average value of the root mean square error decreased from $36.46W/m^2$ to $23.37W/m^2$ in the SWI-PT model, which used different variables of soil moisture and vegetation indices to capture soil evaporation and vegetative transpiration, respectively. By using the EVI and SWI, uncertainties involved in optimizing vegetation and water constraints were reduced. The estimated ET from the MS-PT model was most sensitive (to the normalized difference vegetation index (NDVI) in forests) to net radiation ($R_n$) in grassland and cropland. The estimated ET from the SWI-PT model was most sensitive to $R_n$, followed by SWI, air temperature ($T_a$), and the EVI in each land cover type. Overall, the results showed that the MS-PT model estimates of ET in forest and cropland were weak. By replacing the fraction of soil moisture ($f_{sm}$) with the SWI and the NDVI with the EVI, the newly developed SWI-PT model captured soil evaporation and vegetation transpiration more accurately than the MS-PT model.

• 한국식생활문화학회지
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• 제24권2호
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• pp.191-198
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• 2009

The objective of this study was to investigate the effects of different amounts of pumpkin powder on the quality characteristics of hobakpyeon using physicochemical and sensory properties, as well as on its retrogradation rate during storage. As the amount of pumpkin powder increased, the following effects on the quality characteristics were observed: moisture and amylose contents decreased while protein content increased (p<0.05), and in vitro protein digestibility (IVPD) decreased (p<0.05). Levels of slowly digestible starch and resistant starch fractions increased, while the content of rapidly digestible starch decreased. The starch digestion index and rapidly available glucose content also decreased. Among the physical properties, the L-value decreased while the b-value increased (p<0.05). Texture profile analysis revealed that all textural properties except adhesiveness decreased, and presented significant differences in hardness and chewiness (p<0.05). Sensory properties such as color, flavor, and sweetness increased while others such as wetness and chewiness decreased (p<0.05). Effects on the physicochemical properties during refrigerated storage were also compared between the control and 9% hobakpyeon (9%HP). According to the results, moisture content gradually decreased in the 9%HP compared to the control. Amylose content significantly increased in 9%HP whereas no significant changes were observed in the control. In both types of hobakpyeon, IVSD decreased significantly, showing higher values in 9%HP, whereas mechanical hardness increased, showing lower values in 9%HP. The L-value decreased significantly in the 9%HP whereas no significant changes were observed in the control. In conclusion, the above results suggest that hobakpyeon with low IVSD may be obtained by the addition of 9% pumpkin powder, and also showed that pumpkin powder delayed the rate of retrogradation in 9%HP during storage.

• Preventive Nutrition and Food Science
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• 제16권2호
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• pp.127-134
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• 2011

The purpose of this study was to purify antioxidant substances from steamed squid extract (SSE). The yield of SSE was 8% by dry weight. The approximate compositions of SSE proteins, lipids, moisture, carbohydrate and ash were 64.95%, 1.69%, 7.23%, 4.44% and 21.69%, respectively. The major amino acids in SSE were taurine (29.17%), glycine (20.33%), alanine (12.51%), and glutamic acid (9.83%). Antioxidant activities were evaluated using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity, which was measured as 24.7% at 1.0 mg/mL. Four SSE fractions were isolated by Sephadex G-25 gel chromatography; the F2 fraction showed the highest DPPH radical scavenging activity. The F2 fraction was separated by reverse-phase high performance liquid chromatography (HPLC) using an octadecylsilane (ODS) column, yielding a purified antioxidant substance with a DPPH radical scavenging activity of 64.41% at 1.0 mg/mL, representing a 2.64-fold increase in the scavenging activity of SSE purified by the 3-step procedure. The amino acid compositions showed that purified SSE was rich in taurine, glycine, glutamic acid and alanine. The purified SSE significantly elevated 2',7'-dichlorodihydrofluororescein diacetate (DCFH-DA) fluorescence probe, which confirms its effective radical scavenging potential in cellular ROS. In addition, the SSE significantly inhibited oxidative damage of purified genomic DNA. These results suggest that a purified antioxidant substance from SSE can be used as a potential natural compound-based antioxidant in the functional food and pharmaceutical industries.

• 한국환경농학회지
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• 제25권4호
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• pp.289-296
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• 2006

Various drying conditions, temperatures (40 to $80^{\circ}C$) and durations (overnight to 72 hrs), for the particulate organic matter (POM) fraction after wet-sieving size fractionation have been applied for determination of POM contents in the weight loss-on-ignition method. In this study, we investigated the optimum drying condition for POM fraction in quantification of POM and/or mineral-associated organic matter (MOM; usually indirectly estimated). The influence of the drying conditions on quantifying POM was dependent upon soil properties, especially the amount of soil organic components. In relatively high organic soils (total carbon > 40 g/kg in this study), the POM values were significantly higher (overestimated) with drying at $55^{\circ}C$ than those values at $105^{\circ}C$, which were, for example, 173.2 and 137.3 mg/kg, respectively, in a soil studied. However, drying at $55^{\circ}C$ for longer than 48 hrs of periods produced consistent POM values even though the values were much higher than those at $105^{\circ}C$. Thus, indirect estimates of MOM (MOM = SOM-POM) also tended to be significantly impacted by the dry conditions. Therefore, we suggest POM fractions should be dried at $105^{\circ}C$ for 24 hrs as determining POM and MOM contents. If the POM traction is needed to be dried at a lower temperature (e.g. $55^{\circ}C$) with a specific reason, at least 48 hrs of drying period is necessary to obtain consistent POM values, and a moisture correction factor should be determined to adjust the values back to a $105^{\circ}C$ weight basis.

• Journal of Microbiology and Biotechnology
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• 제11권2호
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• pp.266-274
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• 2001

The chemical properties and physiological activities of the freeze-dried stromata of Cordyceps militaris were examined. A proximate analysis exhibited that the stromata consisted mainly of crude carbohydrate (74.3%), crude protein (11.5%), and moisture content (8.7%), with a low content of crude ash (4.%) and fat (1.3%). The carbohydrate was mostly composed of glucose (88.6%). A large quantity of essential fatty acids, including linolenic acid (33.8%) was also observed. An analysis of the component amino acid showed a relatively high ratio of the essential amino acids, lysine (101.2 mg/g), methionine (62.7 mg/g), and acidic amino acids of glutamic aicd (57.5 mg/g) and aspartic acid (43.9 mg/g), whereas a low of tyrosine content (4.7 mg/g). An examination of the cordycepin content indicated tht the stromata and mycelium-embedded media (silkworm pupae) contained 0.2% and 0.5%, respectively. From the examination of the physiological activities, based on methanol extract (M), ethylacetate extract (EA), and hot-water extract (HW) fractions of the stromata, the hot-water extract (HW) fraction showed the most potent intestinal immune modulating activity, anticoagulant activity, and anticomplementary activity, whereas the ethylacetate extract (EA) fraction exhihited a radical scavenging activity. Therefore, the results from the present study indicate that the stromata of C. militaris contain various healthy chemical ingredients, and that especially boiled water extract of whole body would apprear to provide beneficial physiological activities.

• 한국식품과학회지
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• 제31권4호
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• pp.1120-1123
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• 1999

본 연구는 멸치 자건품의 선상 가공시 유출되는 자숙액 중에 다량으로 함유되어 있는 타우린을 분리, 정제하고자 하였다. 원료 자숙액 중의 타우린 함량은 112.5 mg/100g으로서 총유리아미노산 함량의 38.8%를 차지하였다. 이 자숙액을 Amberlite IR-120과 Amberlite IR-400 column에 순차적으로 적용하여 수율이 79.2%, 순도가 89.9%인 타우린을 얻었다. 또한 이를 다시 에탄올로 정제한 결과, 수율이 29.5%, 순도가 98.1%인 고순도 타우린 결정을 얻을 수 있었다.

• Applied Biological Chemistry
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• 제47권3호
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• pp.315-320
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• 2004

본 연구는 장기능 개선 및 변비 질환의 예방 및 치료에 효과적인 천연 식품인 무(Raphanuse sativa var. nigra L.)로부터 추출, 정제된 조성물, 보다 상세하게는 무의 물 추출물에서 정제 분획된 분자량 3-10 kDa가 주성분으로 장기능 및 변비 질환의 개선 효과를 가지는 조성물에 관한 것이다. 무의 물 추출물을 Balb/c mice를 이용한 활성탄 식이의 장 이동 효과와 SD rats를 이용한 loperamide-induced constipation method에 의한 항변비 효과를 검색하였다. 또한 항변비 효과 검색을 종료한 후, 희생한 횐쥐의 대장관 내 점액질 분비 효과를 조사하였다. 특히, 대장에 많이 존재하는 MUC2 분비 효과를 알아보고자 하였다. 무의 물 추출물은 식수만 투여한 대조군에 비해 용량에 비례해서 활성탄 식이의 장 이동 효과가 현저하게 증가되었고, 다양한 용매 분획에서는 무의 물 분획이 가장 큰 장 이동 효과를 나타내어, 물 분획이 장 이동을 촉진시키는 활성 물질이 가장 많이 함유된 분획으로 확인할 수 있었다. 또한 물 분획을 분자량 크기로 3 kDa 이하, 3-10 kDa, 10-300 kDa, 300 kDa 이상의 4가지 세 분획으로 나누어 활성탄 식이의 장이동 효과를 조사한 결과, 이들 세 분획중에서 3-10 kDa의 분자량을 가진 분획이 주요 구성 물질로 장 이동 촉진 효과를 보였다. Loperamide를 이용해 3-10 kDa의 변비해소 작용을 알아 본 결과에서도 무 물세분획(3-10 kDa) 투여로 변비 유발기간 내내 변량이 증가되었으며, 변비 유발군에 비해, 사료 섭취량의 증가는 변비 유발 물질인 loperamide를 계속 섭취함에도 불구하고 변비가 해소되고 있음을 확인할 수 있었다. 무 물세분획(3-10 kDa)의 대장관내 점액질의 분비에 미치는 영향을 조사한 결과에서도, 대장관 내 변의 개수가 정상군과 거의 같은 수준의 변 개수가 관찰되어 배변촉진 효과가 확인 되었고, 항체(Biogenex AM358)를 사용하여 면역조직 화학법으로 MUC2 관찰시, 변비 유발군에서는 MUC2로 염색된 세포가 현저하계 감소되나, 무 물세분획(3-l0 kDa) 투여시 뚜렷하게 MUC2 염색이 증가되었다.