• Applied Biological Chemistry
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• v.41 no.7
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• pp.510-515
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• 1998

Effect of freezing of soybean and addition of mugwort on the flavor development and the changes of chemical compositions in Chungkookjang was investigated. The changes in the amount of amino-type N, the activities of ${\alpha}-amylase$ and protease, and the content of volatile compounds were determined during aging of Chungkookjang. During ripening, a little higher protease activity was detected in Chungkookjang made of frozen soybean than in that made of non-frozen soybean. However, the profile of ${\alpha}-amylase$ activity of Chungkookjang made of frozen soybean was very similar to that of Chungkookjang made of non-frozen soybean. The amount of amino-type N increased gradually with the ripening period and decreased after 21 days of ripening. The amount of amino-type N was slightly higher in Chungkookjang made of frozen soybean than in that made of non-frozen soybean. Addition of mugwort had little effect on the enzyme activities and the amino-type N content. The mugwort added in Chungkookjang reduced the production of cis-3-hexenol which is responsible for the unpleasant odor, and freezing of soybean enhanced the production of 2, 6-dimethyl pyrazine which is contribute to the taste. According to sensory evaluation, flavor was the highest after the 14 days of ripening and addition of mugwort increased significantly the flavor in both Chungkookjang prepared with frozen soybean and Chungkookjang with non-frozen soybean. However, the effect of freezing of soybean on the flavor was not significant.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.171-184
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• 2007

Chemical admixture stabilization has been extensively used in both shallow and deep stabilization in order to improve inherent properties of the soil such as strength and deformation behavior. An increment in strength, a reduction in compressibility, an improvement of the swelling or squeezing characteristics and increasing the durability of soil are the main aims of the admixtures for soil stabilization. Recently, the various advanced cement stabilizer mixing technique was developed. Advanced cement stabilizer mixing technique is environmentally-friendly and has an excellent mixing property and outstanding mixing speed. In this study, to develop the rural road pavement technology using cement stabilizer, compaction and unconfined compression test were performed with various mixing ratio and two types of soil(clay and silty soil). And the freezing/thaw test and bending strength test performed to develop suitable cement stabilizer material for stabilization of rural road. Based on the test results, the liquid types of cement stabilizer material and silty soil mixture are most suitable for rural road construction and although the mixing ratio is low, cement stabilizer mixture is effective for durability of rural road surface layer.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.37-43
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• 2015

Korea has four distinct seasons, showing hot and humidity in summer and cold weather lasted in winter. Domestic research on earth work has been developed according to the seasonal characteristics, and most of research topics have focused on the effect of freezing-thawing on the performance of geo-materials. However, the previous research was performed on the ground compacted at room temperature and therefore, the effect of the sub-zero temperature at the time of construction was not fully investigated. The ground characteristics compacted at freezing temperature can be different from those at room temperature and show different characteristics of strength and deformation caused by freezing and thawing. Therefore, the compaction tests on sandy materials were conducted under various temperature at $-3^{\circ}C$ and $-8^{\circ}C$ with various fine contents of 0%, 5%, 10% and 15% in weight fraction. The effectiveness of soil compaction at below-freezing temperatures were compared with the compaction at room temperature at $18^{\circ}C$ in terms of the maximum dry unit weight and optimum water contents. Based on the test results, the maximum dry unit weight tends to decrease with the freezing temperature and the relative compaction at $-8^{\circ}C$ can not be satisfied with general specification standard.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.484-490
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• 2001

This study focused on the investigation of durability of latex modified concrete in the points of chloride ion permeability and freeze-thaw resistance as latex content variated such as 5%, 10%, 15% and 20%. When latex was mixed in concrete and cured, the concrete consisted of hydrated cement and aggregate interconnected by a film of latex particles. An increasing the amount of latex produced concrete with increased flexural strength, but with slightly lower compressive strength. The increase in flexural strength might be attributed to the latex films between the hydrated cement and aggregates, and the decrease in compressive strength to the flexibility of the latex component named by Butadiene. The rapid chloride permeability test was used to evaluate the relative permeability of latex-modified concretes and conventional concretes. The results showed that the permeability of latex-modified concretes was considerably lower than conventional concretes tested, which might be due to the latex filled in voids and interconnections of hydrated cement and aggregates by a film of latex particles. The freeze-thaw resistance of LMC was quite good comparing to conventional concrete. Air entraining agent has been used in conventional concrete to improve the freeze/thaw resistance, but latex modified concrete does not need additional air entraining agent for freeze-thaw resistance provided adequate cure occurs.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.128-137
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• 1999

In this study, shiitake mushrooms were dried by hot air, vacuum and freeze drying methods and theire physical properties were compared. Since the pore size affects the amount of absorption, the characteristics of water sorption were investigated at various humidities and temperatures. Results showed that the freeze dried product had the greatest pore area and the highest absorption capacity. However, all the dried samples showed similar quality. The browning degrees were severely changed with increased relative humidities and temperatures. Among these drying methods, the freeze drying gave the greatest change in browning degree. The GAB monolayer moisture contents of the dried shiitake mushroom were $5.3{\sim}7.7%$. The prediction model was also provided using parameters such as relative humidity, temperature and pore area.

• Food Science and Preservation
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• v.12 no.5
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• pp.449-454
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• 2005

The objective of this study was to investigate the effect of drying methods on the physicochemical characteristics of Ponciri fructus. Immature fruits of Poncirus trifoliata were harvested, dried by shade, infrared, or freeze drying, and powdered to size of 20 mesh. Then, extracted for 3 hrs with hot-water or 40% ethanol(80$\circC$℃). Freeze dried powder showed significantly higher L and -a value. The content of hesperidin was not affected by drying methods. The yield was the highest from freeze drying. Water extracts showed significantly more browning color, and higher acidity and total sugar content than those of ethanol extracts. Acidity and total sugar of water extracts were the highest in infrared drying and freeze drying, respectively. Browning color, pH, acidity and total sugar of ethanol extracts were not affected by the drying methods. The results suggest that freeze drying has a beneficial effects to enhance the quality of Ponciri fructus.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.197-208
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• 2003

This paper is to determine the possibility of re-using waste concrete from Incheon city area. The strength test was conducted with five aggregate compounds which was replaced a natural aggregate with recycled aggregate. After checking the physical characteristics of recycled aggregate compounds, the mix design of recycled concrete was conducted. For the relatively comparison between natural and recycled compounds, while the unit aggregate weight was changed, other conditions were fixed. The freezing and thawing test which included fly-ash and super-plastezer were performed to check the durability and workability when recycling waste concrete. In the physical characteristics of recycled aggregate, it was found that the specific gravity of recycled coarse aggregate and recycled fine aggregate satisfied the first grade of recycle specification(KS), and all compounds of recycled aggregate also satisfied the second grade of absorption specification, Especially up to the 50% substitution of recycled aggregate is equal to or a bit lower than that of convention aggregate. In comparison with conventional concrete, the recycled concrete is lower than maximum by 7% in compressive strength decreasing rate after freezing-thawing test. From now, although most of recycled concrete was used to the building lot, subgrade, asphalt admixture, through the result. It was proved that possibility of re-using recycled aggregate as the substructure of bridge, retaining wall, tunnel lining and concrete structure which is not attacked the drying shrinkage severely.

• Food Science and Preservation
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• v.24 no.2
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• pp.246-253
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• 2017

This study was conducted prepare spray-dried powder using pumpkin sweet potato hydrolysates and examine the physicochemical properties of the powder. The insoluble dietary fiber and soluble dietary fiber of the pumpkin sweet potato treated by enzyme were 4.17% and 2.07%, respectively. The spray-dried pumpkin sweet potato hydrolysates was manufactured via spray-drying with different forming agents: i.e., pectin 0.1%, 0.5%, 1%, and 2.0%. The moisture contents and total starches of the spray-dried powders were approximately 1.68-2.46 and 45.32-46.51%, respectively. The color of the L and a value decreased, and that of the b and ${\Delta}E$ value increased. The particle size and outer topology of the spray-dried powders were $37.17-42.32{\mu}m$, and its shape was generally globular. The water absorption index of the spray-dried powder (1.74-1.91) was lower than that of the freeze-dried powder (2.15). The water solubility index of the spray-dried powder, 80.75-87.61%, was higher than that of the freeze-dried powder (70.47%). The adhesion values of spray-dried powder to epithelial HT-29 cells were 2.66-6.18% of the initial cell counts, whereas freeze-dried powder showed lower adhesive ability (1.79%). The in vitro human digestibility in the spray-dried powder was 70.09% which is very effective in digestion.

• Journal of the Korean Geotechnical Society
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• v.32 no.6
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• pp.17-26
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• 2016

Characteristic behaviors of geo-structure during freezing and thawing process have to be understood based on fundamental knowledge on phase change in porous soil and interaction between soil and structure. Inversion analysis using published one-dimensional soil freezing tests was conducted to suggest a mechanical model to consider an effect of the ice saturation on Young's modulus. Silty soil was more sensitive to temperature than weathered granite soil and sand, and weathered granite soil was more affected by initial water saturation in stiffness decrease than silty soil. Numerical simulations on chilled gas pipeline showed that shielding effect from surrounding frozen zone around the pipe decreases impact from external load onto the pipe. And a pipe installed in sand backfill showed more heaving due to relatively low stiffness of sand during freezing than that of surrounding in-situ weather granite soil. However, it had more stable stress condition due to effective stress redistribution from external load.

• Applied Microscopy
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• v.20 no.2
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• pp.81-101
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• 1990

Toad bladder의 상피수송(上皮輸送)을 분석(分析)하기 위하여 동결치환(凍結置換) 및 동결절단법(凍結切斷法)을 적용(適用)하여 전자현미경(電子顯微鏡) 관찰(觀察)을 실시하였다. 방광(膀胱)의 점막층(粘膜層)은 과립성세포(顆粒性細胞), 미토콘드리아가 풍부한 세포, 점막분필세포(粘膜分泌細胞) 및 기저세포(基底細胞)등 4가지 세포로 구성되어 있었다. 과립성세포(顆粒性細胞)는 점막표면적의 대부분을 점유하며 $Na^+$ 수송(輸送)에 주요한 역할을 하고, 정단부(頂端部)의 세포질에는 다수의 과립이 분포하며 정단세포막(頂端細胞膜)은 microvilli type I로 배열되어 있고, 표면에 glycoprotein을 함유하는 세포외막(細胞外膜)이 관찰되었다. 대조적으로 미토콘드리아가 풍부한 세포는 세포질 전역에 걸쳐 다수의 미토콘드리아가 분포해 있으며 주요 기능은 $H^{+},\;K^{+}$ 및 $HCO_{3}^{-}$ 분필수송(分泌輸送)에 관여할 것으로 생각되며 이들 수송상피(輸送上皮)는 정단부가 견고연접(堅固連接)으로 둘러 싸이고 기저세포막(基底細胞膜)은 인접세포와 서로 분리되므로 상피세포의 극성이 유지되며 정단부(頂端部) 세포막과 기저세포막의 수송특성(輸送特性)은 각기 다르다고 생각된다. 따라서 두꺼비 방광(膀胱)에서 상피수송(上皮輸送)은 세포 통과수송 및 세포간 분류수송 경로를 나타내고 있다. 한편 세포막 투과성(透過性)의 조절과 관련하여 동결절단(凍結切斷) 전자현미경 관찰에 의하면 forskolin에 촉진된 정단부(頂端部) 세포막 투과성의 변화는 세포막내(細胞膜內) 입자(粒子)의 분포와 밀접한 관계를 가지는 것으로 보인다. 특히 과립성세포(顆粒性細胞)에서 집단으로 관찰되는 세포막내(細胞膜內) 입자(粒子)는 forskolin에 유도된 정단세포막(頂端細胞膜) 투과성의 변화를 나타내주는 것으로 사료되나 이의 기능적 의미에 대하여는 연구가 더욱 필요하다고 본다.