• Journal of Conservation Science
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• v.37 no.2
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• pp.101-119
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• 2021

Korea's National Treasure No. 229, the Jagyeongnu (clepsydra) of Changgyeonggung Palace, is a scientific and cultural property representing the pinnacle of science and technology in the Joseon Dynasty. Currently, only the large, mid-sie, and small Pasuhos (bronze jars) remain. During a nearly two-year conservation project by the Cultural Heritage Conservation Science Center (CHCSC) that began in 2018, conservators identified the contaminants on the surface of the water clock's components. It turned out that the contaminants had been caused by the exposure of squalane and silicone oil, used in an earlier preservation treatment, to the elements. The CHCSC conducted experiments to determine the most effective method to remove the contaminants. First, the conservators tried using an organic solvent, a poultice, and the application of toluene and bentonite, which yielded excellent reactivity and significant color difference changes (𝚫E). However, the reactivity was insufficiently effective to warrant the health hazards to the conservators and the environment (toluene is toxic). Although organic solvents required considerably more effort, time, and human resources, the conservators confirmed that their use achieved a true color difference variation (𝚫E) that was within the same range as the toxic hydrocarbon. Thus, they confirmed that using an organic surfactant was the best method for removing the contaminants.

• Food Engineering Progress
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• v.21 no.1
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• pp.42-48
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• 2017

The purpose of this study was to verify the drying characteristics of steamed sweet potato and to establish optimal drying conditions for far-infrared drying of steamed sweet potato. 4 kg of steamed sweet potato was sliced to thicknesses of 8 and 10 mm, and dried by a far-infrared dryer until a final moisture content of $25{\pm}0.5%$. The far-infrared dryer conditions were an air velocity of 0.6, 0.8 m/s and drying temperature of 60, 70, and $80^{\circ}C$. The results can be summarized as follows. The drying time tended to be reduced as temperature and air velocity for drying increased. The Lewis and Modified Wang and Singh models were found to be suitable for drying of steamed sweet potato by a far-infrared dryer. The color difference was 35.09 on the following conditions: Thickness of 8 mm, temperature of $80^{\circ}C$, and air velocity of 0.8 m/s. The highest sugar content ($59.11^{\circ}Brix$) was observed on the conditions of a thickness of 8 mm, temperature of 80, and air velocity of 0.8 m/s. Energy consumption decreased on the conditions of higher temperature, slower air velocity, and thinner steamed sweet potato.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.171-175
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• 1999

Changes in physicochemical characteristics of steamed rice during roasting were investigated. Steamed rice was roasted at various temperature $(150{\sim}220^{\circ}C)$ for various time $(10{\sim}30min)$. L and b Hunter color values of steamed rice were decreased, but E value was increased by roasting. The water absorption index and the water solubility index were gradually with increasing roasting temperature and time up to $200^{\circ}C$ for 30min, but decreased at $220^{\circ}C$ for 20min. The yield of water extracts from steamed and roasted rice were sharply increased with increasing roasting temperature and time, however, precipitates and turbidity were decreased. The content of reducing sugar was slowly increased up to $200^{\circ}C$ and remarkably increased above it. The contents of amino acids were decreased by roasting. Among them, cystine, lysine and serin were significantly reduced with increasing roasting temperature.

• Journal of Mushroom
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• v.19 no.4
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• pp.329-335
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• 2021

This experiment was conducted to investigate the changes in freshness parameters and determine the optimal UV-B irradiation conditions for each storage period for Heuktari, an oyster mushroom cultivar, grown under LED lightNo significant changes were observed in the CO₂ and O₂ content until day 12 of storage; however, after day 15, the CO₂/O₂ ratios were higher in the UV-treated groups than in the untreated groups. No color difference was observed between the UV-treated and untreated groups. In all UV-treated groups, hardness decreased over time; however, the group irradiated for 15 minutes showed higher hardness values than those of the untreated group. The UV-irradiated group showed higher ergosterol content than did the untreated group, and scanning electron microscopy revealed that mushroom cell wall destruction increased with increased UV treatment time. Overall, these findings confirmed that UV-B irradiation increased the ergosterol content of Heuktari but decreased its freshness and negatively impacted other storage characteristics.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.718-724
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• 1999

This study was investigated the changes of the properties of matter such as the gel formation of the combined fish based on the mixed rate between the ocean jumbo squid and Alaska pollock surimi, and compared the relationships between the gel formation and water holding capacity. The changes of the gel formation based on 20 min fish grinding time and $2.5\%$ salt concentration according to the mixed rate was thought as the optimal addition limit. There was no significant function of gel product more than $20\%$ Jumbo squid meat. The more squid meat in the mixed meat could make the lower breaking stress but 7:3 rate of pollock : squid could retain breaking strain. The effect of the moisture content on mixed fish meat was studied and the drastic decrease of the gel formation and water holding capacity was indicated in $78\%$.

• Korean Journal of Heritage: History & Science
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• v.46 no.1
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• pp.176-187
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• 2013

A study has been carried out on metal materials in order to identify the quantitative relation between the concentration and damage characteristics after evaluation of the damage characteristics according to the $SO_2$ concentration. The prepared metal samples, which were categorized according to the material (silver, copper, iron, lead, brass) were exposed to 0.01, 0.12, 1, 10, 100, 1,000, and 5,000ppm of $SO_2$ for 24 hours and the optical, physical, chemical deterioration rates both before and after testing were evaluated. The results showed optical deterioration, a loss of gloss on silver specimen with $SO_2$ 100ppm, an increase of color difference on brass, iron, copper and lead specimens with $SO_2$ 5,000ppm, as well as physical changes such as an increase of thickness and corrosion rate on iron sample with $SO_2$ 5,000ppm. In the case of chemical changes such as an increase sulfate ion ($SO{_4}^{2-}$) concentration and decrease of pH on iron and brass specimens were identified. These results suggest that $SO_2$ 100ppm caused clear optical deterioration on some metals such as silver and physicochemical and optical deterioration were identified at $SO_2$ 5,000ppm regardless of metal type. Also, It was concluded that iron and brass are the most susceptible of the metal specimens to $SO_2$.

• Food Science and Preservation
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• v.21 no.5
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• pp.694-701
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• 2014

The quality characteristics of blanched Aster scaber with the blanching condition and various solutes (non-treated, NT; soluble Ca, SC; sodium bicarbonate, SB; and magnesium sulfate, MS) were evaluated with different blanching times and solutes. The blanching process decreased the total polyphenolics, ascorbic acid contents, hardness, and cutting strength of the leaves. As for the pectinesterase and polygalacturonase, the blanching process increased their inhibitory activities, and more than 90% of them were inactivated in all the samples that were blanched. For the total counts and the number of coliform groups, the number of total aerobes at 5.92-log CFU/g before the blanching process was reduced to the approximately 2-3 log scale, and the coliform group was not detected after the blanching. The blanching also significantly decreased the total chlorophyll a and b ratios. The sensory characteristics of the Aster scaber according to the test group showed that the leaves blanched for 3 min were the most highly evaluated in terms of their overall acceptability. The phenolic compound, chlorophyll, and carotenoid contents tended to increase from before their blanching, and the Ca/Cb ratio was higher in the SC. These results showed that SC and MS treatment had greater effects on the quality characteristics and the pigmentation.

• Journal of Conservation Science
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• v.31 no.4
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• pp.373-386
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• 2015

This study identified degradation properties by temperature stress with Araldite$^{(R)}$ AY103-1/HY956 used for ceramics. Tensile and compressive strength of durability increased for 6,480 hours at temperature of $34{\sim}45^{\circ}C$. In stability of external stress and temperature, compressive strength is superior to tensile strength, it requires conservation plans considering strength properties and stress of restoration materials. The tensile shear strength of adhesion properties decreased for 4,320 hours at temperature of $40{\sim}60^{\circ}C$. In ceramics with porosity, environments under isothermal-isohumidity are important because interfacial properties of adherend are concerned with performance variation. Glossiness decreased for 6,480 hours at temperature of $34{\sim}45^{\circ}C$ and color difference increased. Gloss stability was superior and color stability was weak, which requires improvement of optical properties. In artifacts on display in museums, there is concern about temperature rise on restoration materials by lighting therefore, it needs to minimize change in physical properties by exposure environments.

• Polymer(Korea)
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• v.37 no.2
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• pp.204-210
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• 2013

Effects of additives (lubricant and antioxidant) and melt-blending condition (temperature, time and rotor speed) on the mechanical properties of polypropylene-based wood polymer composites (WPCs) were investigated. WPCs were prepared by melt-blending followed by compression molding. To understand melt-blending procedure, torque change of the WPC melt-blend was monitored. Maleic anhydride modified PP and nanoclay were used as a compatibilizer and a reinforcing filler, respectively. UTM and izod impact tester were used to measure the mechanical properties of the WPCs and a color-difference meter was used to measure the discoloration of the WPCs according to melt-blending condition. The mechanical properties showed that the optimized melt-blending condition was $170^{\circ}C$, 15 min, and 60 rpm. The mechanical properties of the WPCs decreased with increasing lubricant and antioxidant content. The two step method, adding wood flour later separately during melt-blending, was more effective than the typical one step method for improving the mechanical properties of the WPCs.

• Journal of Fisheries and Marine Sciences Education
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• v.18 no.3
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• pp.293-301
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• 2006

This study was undertaken to prolonging the freshness in Squid(Todarodes pacificus) on the effects of ice storage methods(tap water ice, electrolytic water ice) using stainless diaphragm electrolytic instrument and also test an efficiency of instrument. Basically, stainless diaphragm electrolytic instrument studied for changes of pH on difference water flow and ampere. The lower water flower and higher ampere made low pH on acid part of electrolytic instrument. Squid samples were stored in tap water ice, acid part of electrolytic water and base part of electrolytic water and used in studying the changes of VBN and skin color through storage. Acid water had strong sterilization effects and VBN was lower levels of acid water than the others. Base water had not sterilization effects. Tap water ice storage was more sterilizing effects than base water ice storage but less effects than acid water ice storage. Lightness of Squid skin showed getting decrease at storage of ice water of all storage methods but acid water ice storage showed more retarding than the other two storage. From these results, it could be suggested that acid electric water ice storage is effective in extendance the shelf-life of squid at chilled storage.