• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.62-69
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• 2023

This study investigated the electromechanical properties of cement based smart repair materials (SRMs) according to the different amounts of fine steel slag aggregates (FSSAs). SRMs can self-diagnose the quality of repairing and self-sense the damage of repaired zone. The replacement ratios of FSSAs to sand for SRMs were 0% (FSSA00), 25% (FSSA25), and 50% (FSSA50) by sand weight. The electrical resistivity of SRMs generally decreased as the compressive stress of SRMs increased: the electrical resistivity of FSSA25 at the age of 7 hours decreased from 78.16 to 63.68 kΩ-cm as the compressive stress increased from 0 to 22.37 MPa. As the replacement ratio of FSSAs by weight of sand increased from 0% to 25%, the stress sensitivity coefficient (SSC) of SRM at the age of 7 h increased from 0.471 to 0.828 %/MPa owing to the increased number of partially conductive paths in the SRMs. However, as the replacement ratio of FSSAs further increased up to 50%, the SSC decreased from 0.828 to 0.649 %/MPa because some of the partially conductive paths changed to continued conductive ones. SRMs are expected to self-sense the quality and future damage of repaired zone only by measuring the electrical resistivity of the repaired zone in addition to fast recovery in the mechanical resistance of structures.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.305-312
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• 2013

This paper reports the results of an investigation into the effects of silica fume on strength properties of alkali-activated slag cement (AASC) with water-binder (W/B) ratio and replacement ratio of silica fume content. The W/B ratio varied between 0.50 and 0.60 at a constant increment of 0.05. The silica fume content varied from 0% to 50% by weight of slag. The activators was used sodium hydroxide (NaOH) and the dosage of activator was 3M. The strength development with W/B ratio has been studied at different ages of 1, 3, 7 and 28 days. For mixes of AASC mortars with varying silica fume content, the flow values were lower than the control mixes (without silica fume). The flow value was decrease as the content of silica fume increase. This is because the higher surface areas of silica fume particles increase the water requirement. The analysis of these results indicates that, increasing the silica fume content in AASC mortar also increased the compressive strength. Moreover, the strength decreases with the W/B ratios increases. This is because the particle sizes of silica fume are smaller than slag. The high compressive strength of blended slag-silica fume mortars was due to both the filler effect and the activated reaction of silica fume evidently giving the mortar matrix a denser microstructure, thereby resulting in a significant gain in strength.

• Food Science and Preservation
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• v.9 no.2
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• pp.126-130
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• 2002

Optimal storage conditions were investigated for 'Fuyu' persimmon fruits and cucumbers were stored under conditions of 70% relative humidity(RH) at 25$^{\circ}C$, 80% RH at l0$^{\circ}C$ and 90% at 5$^{\circ}C$ or l0$^{\circ}C$ of relative humidity, respectively and their qualities in microbial counts, decay ratio, surface color difference and chemical attributes were monitored during the storage period. 'Fuyu'persimmon fruits and cucumbers stored under 90% of relative humidity showed the minimal change in weight loss, decrease of ascorbic acid content, surface color difference and decay by putrefactive microorganisms. As the results of this experiment, 'Fuyu' persimmon fruits and cucumberf stored under 9% of relative humidity were best fer maintaining their freshness.

• Food Science and Preservation
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• v.8 no.3
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• pp.269-273
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• 2001

Apples and pears for investigating the optimal storage conditions were purchased from the farmhouse located in Hadong-Goon and Geochang-Goon Gyeongnam just before the beginning of this experiment. Apples and pears were, stored under 70%(storage temperature : 25$^{\circ}C$), 80%(10$^{\circ}C$) and 90%(5$^{\circ}C$) of relative humidity, respectively and their qualities in microbial counts, decay ratio, surface color difference and chemical attributes were monitored during the storage period. Apples and pears stored under 70% of relative humidity showed the minimal change in weight lass, decrease ratio of ascorbic acid content, surface color difference and degrees contaminated by putrefactive microorganisms. As the results of this experiment, apples and pears stored under 90% of relative humidity showed the optimal storage conditions for maintaining their freshness.

• Food Science and Preservation
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• v.6 no.2
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• pp.143-147
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• 1999

Onions were subject to quality evaluation from the physiological and physicochemical points of view during storage under different conditions, which were low temperature (2-4$^{\circ}C$, 80% RH), pit temperature (3-15$^{\circ}C$, 75-85% RH), room temperature (10-23$^{\circ}C$, 75-98% RH) and ambient temperature (2-25$^{\circ}C$, 62-72% RH). Sprouting were dereloped from the 11th month of storage in low temperature. Rotting was quickly occurred from the 7th month of storage excepting onions in room temperature. Low temperature storage showed the least weight change. Moisture content increased with the lapse of storage time at both low temperature and pit temperature storage conditions, but decreased with the lapse of storage time at room and ambient temperature conditions. Total and reducing sugars decreased with the storage time, while vitamin increased in stored onions at low temperature.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1452-1460
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• 2013

The purpose of this study was to investigate secondary drying effects on garlic quality, and to define the optimal secondary drying conditions for garlic preservation. The secondary drying tests used garlic that was naturally dried once and stored at low temperature. After secondary drying, the garlic was stored in a warehouse at room temperature. Tests were performed at different low-temperature storage periods (60, 105, 150, 195, and 240 days), secondary drying temperatures (35 and $40^{\circ}C$), drying times (1, 2, 3 days), and room temperature storage periods (15, 30, and 45 days). The results were compared with a non-secondary drying condition control. In general, the $40^{\circ}C$-2 days dry conditions showed the lowest weight-loss rate (5%) and rotting rate during room temperature storage. The sprouting rate increased by 20% during the initial 15 day-room temperature storage, along with a small increase after 30 days of room temperature storage. Increases in drying temperature and the period of secondary drying conditions caused a decrease in firmness. In addition, the sprouting rate was 10% higher, and rotting rate 5~10% higher, for the non-drying condition, compared to drying conditions. Based on our results, the $40^{\circ}C$-2 days drying condition is the optimal secondary drying condition for garlic storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.10
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• pp.1415-1421
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• 2015

This study was performed to investigate the effects of puffed-red ginseng (PRG) powder and drink on blood glucose level and serum lipid profile in streptozotocin (STZ)-induced diabetic rats. For the experimental design, STZ-induced diabetic rats were fed PRG powder-supplemented diets (0.3%, 0.6%) and diluted drinks (0.14%, 0.28%) for 6 weeks. Concentrations of blood glucose during the experimental period decreased to 18.3 mg/dL in the 0.6% PRG diet group and 15.1 mg/dL in the 0.14% PRG drink group. Average reduction rate of blood glucose in the last week compared to reference blood glucose concentration decreased by 19.2% (A group), 37.4% (B group), 18.7% (C group), and 17.3% (D group) in the PRG treatment groups, respectively. These results indicate that PRG affects blood glucose via ginseng saponins administered in diet or drinking water, thereby suggesting that PRG has the ability to prevent increasing blood glucose in mild-induced diabetic rats.

• Journal of Mushroom
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• v.11 no.1
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• pp.41-45
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• 2013

This study was carried out to improve standardization of agricultural products and investigate quality changes during preservation at various treatments. The standardization does much to improve merchantable quality, distribution efficiency and fair dealings by shipping of the standard agricultural products. Mushrooms notified as the standard are five; Pleurotus ostreatus, Pleurotus eryngii, Flammulina velutipes, Agaricus bisporus and Ganoderma lucidum. But many farmers are suffering from strict standards. Therefore, modification of these standards is required to fit farmhouse situations. Fruit-body weight of A, B and C grades of the marketed Agaricus bisporus was 19.3g, 12.2g and 10.4, respectively. Average pileus diameter of A grades was 43.3mm but B and C grades did not show significant difference. Average stipe length of A, B and C grades was 9.8mm, 13.1mm and 11.6mm, and stipes thick was the highest in A grades. The weight loss rate of stipe cutting of Agaricus bisporus was 12.6% in harvested mushrooms and the rate of stipe cutting length was 60.8%. The diameter of Agaricus bisporus stored for 5 days was 3.5~4.5cm but decreased rapidly in 15 days. The weight loss rate of the high temperature samples lowered rapidly than that of the low temperature samples. Conversely, the L value of the low temperature samples was higher than that of the high temperature samples.

• Korean Journal of Plant Resources
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• v.25 no.5
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• pp.591-595
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• 2012

This study was conducted to investigate the possibility of changes in onion (cv. 'Turbo' and 'Changnyongdaego') bulb quality during storage at room and cold temperature. Increased weight loss was found in the onion bulb stored at both cold and room temperature conditions. 4% weight loss was found in bulbs stored at room temperature and 2% at cold storage as compared to fresh cultivated onion bulb; after three months. Initially, there was no significant difference in the firmness of bulbs between cultivars and storage conditions. Hunter a value of bulb stored at room temperature was higher than the value of bulb stored at cold temperature. 27% and 7.9% decay was found after three months in 'Changnyongdaego' and 'Turbo' cultivars stored under room temperature condition respectively. In contrast, only 2% decay was noticed in both cultivars stored at cold storage condition. Hunter L value of onion bulb gradually decreased in both room and cold temperature storage conditions. In conclusion, quality of onion bulb can be maintained until three months. For long term storage and quality maintenance, under room temperature conditions a resistance cultivar should be selected.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.24-34
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• 2020

This research is a study on the characteristics of OPC-slag cement using nano-silica solution (NSS) with water-weight substitution method. The new replacement method is a fundamental step to study the behavior of cement with higher NSS replacement rates than previous studies. NSS was replaced by 10%, 20%, 30%, 40%, and 50% of the mixing water weight. As a result, the mechanical and microstructural characteristics were improved. This can be summarized in two ways. First, when the NSS is replaced with mixing water, the homogeneous dispersion action of the nano-silica particles is improved. This promotes initial hydration. Second, substitution of NSS with higher density than mixing water reduces w / b. This forms a dense hydration reaction material. The new substitution method did not show any degradation of mechanical and microstructural properties as compared with the results using the powdered nano-silica particles revealed in the previous study. Therefore, it is considered that the method of weight substitution of NSS used in this study can be applied to the formulation of OPC-slag cement.