• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.3
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• pp.157-170
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• 2002

The purpose of this study is to analyze the shear bond strength according to kinds of surface treatment agents and resin cements after acid etching of IPS Empress 2. For this purpose, test groups were classified into silane-treated bonding groups, silica-coated group and Targis link applied group. Then, nine bonding groups in total, each three groups per kind, were prepared by using three kinds of resin cements-Panavia F, Variolink II and Rely-X ARC, and thirty test specimens per group were prepared. To examine any changes in the oral environment, the shear bond strength of each test specimen was measured after dipping test for 24 hours and for five weeks, respectively, in distilled water at $37^{\circ}C$ and performing heat cycle 10,000 times in total, each 2,000 times per week, during a five weeks of dipping, under the condition similar to the oral environment. The bond failure modes were also observed by means of a scanning electron microscope. The results are summarized as follows 1. Statically significant differences between the surface conditioning materials were observed. The shear strength of the silane treatment was the highest of all three types of surface treatments(p<0.001). 2. Shear strengths varied significantly for different types of resin luting agents. But bond strength of Targis link surface treatments were not significantly different(p<0.05). 3. No significant difference of bonding strengths was found between storage time conditions(24 hours and 5 weeks). Only group II, IV, VII, IX were significantly different(p<0.05). 4. After thermocycling, the shear bond strengths of all groups were significantly decreased (p<0.05). Group III, V, VI were no significantly different. 5. On the SEM observation of fractured surfaces, all groups were shown complex failure.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.7
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• pp.879-884
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• 2009

Allium tuberosum Rotter (Liliaceae, Chinese chives) is a perennial herb of which leaves are used for food. This study investigated the effect of pretreatment on quality of dehydrated Chinese chives. Chinese chives was blanched at $80^{\circ}C$ for 20 sec, followed by drying at $70^{\circ}C$, $80^{\circ}C$, $100^{\circ}C$, or drying at $100^{\circ}C$ for 30 min and subsequent drying at $70^{\circ}C$, or $100^{\circ}C$ for 60 min and subsequent drying at $70^{\circ}C$. Optimum drying temperature and time was $100^{\circ}C$ for 30 min and subsequent drying at $70^{\circ}C$, or $100^{\circ}C$ for 60 min and subsequent drying at $70^{\circ}C$. These conditions were shortened time for dehydration and showed smaller decrease than others in Hunter color L, a, b. Dehydrated Chinese chives showed a constant decrease in greenness with storage, probably due to destruction of chlorophyll by light. In the measurement of Hunter color L, a, b, these conditions showed smaller decrease than others in Hunter color for 15 week storage. Chlorophyll content and SOD (superoxide dismutase)-like activity in that condition was higher than others. It was assumed that a phenolic compound that forms its thermostable activity. The fitness of drying models was conducted in order to explain reducing chlorophyll loss and SOD (superoxide dismutase)-like activity loss. Based upon the chlorophyll content, SOD-like activity, and retention of green color of the vegetable, optimum drying conditions was $100^{\circ}C$ for 30 min followed by $100^{\circ}C$ for 30 min and subsequent drying at $70^{\circ}C$, or $100^{\circ}C$ for 60 min and subsequent drying at $70^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.33 no.4
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• pp.444-450
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• 2001

Kochujang, fermented hot pepper paste, was treated with combined high hydrostatic pressure and heat. Viable cell counts and chemical compositions of Kochujang were determined as a function of high pressure processing conditions such as temperature, pressure and time, and during storage for 120 days at $37^{\circ}C$. Viable cell counts were decreased with the increase of temperature, pressure and time. Viable cell counts in the treated Kochujang were decreased up to $0{\sim}3$ log cycle with the temperature of $49{\sim}73^{\circ}C$, $0{\sim}3$ log cycle with the pressure of $380{\sim}680\;MPa$, and $2{\sim}5$ log cycle with the time of $10{\sim}70\;min$, compared with the untreated. pH, titratable acidity, amino nitrogen, reducing sugar and ethanol content in the treated Kochujang were comparable to the untreated regardless of the treatment condition. Hunter L, a and b values in the treated Kochujang were higher than those of the untreated. Viable cell counts were decreased with the increase of the storage period at $37^{\circ}C$. Viable cell counts in Kochujang treated at 380 MPa/30 min were decreased up to 2 log cycle from $1.8{\times}10^6\;to\;1.94{\times}10^4\;CFU/g$ after 120 days of storage, while those at 680 MPa/70 min were not detected after 60 days from the initial stage of $4.00{\times}10^1\;CFU/g$. pH, amino nitrogen and ethanol content were decreased, and titratable acidity were increased significantly as the increase of the storage period. Hunter L, a and b values also decreased significantly. The changes in physicochemical properties of Kochujang treated at 680 MPa/70 min were greater than those at 380 MPa/30 min.

• 한국유가공학회:학술대회논문집
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• 2002.11a
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• pp.23-40
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• 2002

This study was conducted to investigate the quality changes of the UHT(ultra-high temperature), LTLT(law temperature long time) and HTST(high temperature short time) treated milk samples by storage conditions for 6 months from August 2000 to February 2001. The UHT treated milk samples collected from 3 plants(A, B and C) were stored at l0$^{\circ}$C and room temperature(dark and light exposure) for 6 months, and the LTLT and HTST treated milk samples(D and E) were also stored for 30 days. The UHT pasteurized milk of A, B and C plant was treated at 130$^{\circ}$C for 2-3s, 133$^{\circ}$C for 2-3s and 135$^{\circ}$C for 4s, respectively. The UHT sterilized milk of A and B plant was treated at 140$^{\circ}$C for 2-3s and 145$^{\circ}$C for 3-4s, respectively. The LTLT milk of D plant was treated at 63$^{\circ}$C for 30 mins, and the HTST milk of E plant was treated at 72$^{\circ}$C for 15s. All of the raw milk samples collected from storage tank in 5 milk plants were showed less than 4.0 X 10$^5$cfu/ml in standard plate count, and normal level in acidity, specific gravity, and component of milk. Preservatives, antibiotics, sulfonamides and available chloride were not detected in both raw and heat treated milk samples obtained from 5 plants. One(10%) of 10 UHT pasteurized milk samples obtained from B plant and 2 (20%) of 10 from C were not detected in bacterial count after storage at 37$^{\circ}$C for 14 days, but all of the 10 milk samples from A were detected. No coliforms were detected in all samples tested. No bacteria were also detected in carton, polyethylene and tetra packs collected from the milk plants. A total of 300 UHT pasteurized milk samples collected from 3 plants were stored at room(3$^{\circ}$C ${\sim}$ 30$^{\circ}$C) for 3 and 6 months, 11.3%(34/300) were kept normal in sensory test, and 10.7%(32/300)were negative in bacterial count. The UHT pasteurized milk from A deteriorated faster than the UHT pasteurized milk from B and C. The bacterial counts in the UHT pasteurized milk samples stored at 10$^{\circ}$C were kept less than standard limit(2 ${\times}$ 10$^4$ cfu/ml) of bacteria for 5 days, and bacterial counts in some milk samples were a slightly increased more than the standard limit as time elapsed for 6 months. When the milk samples were stored at room(3$^{\circ}$C ${\sim}$ 30$^{\circ}$C), the bacterial counts in most of the milk samples from A plant were more than the standard limit after 3 days of storage, but in the 20%${\sim}$30%(4${\sim}$6/20) of the milk samples from B and C were less than the standard limit after 6 months of storage. The bacterial counts in the LTLT and HTST pasteurized milk samples were about 4.0 ${\times}$ 10$^3$ and 1.5 ${\times}$ 101CFU/ml at the production day, respectively. The bacterial counts in the samples were rapidly increased to more than 10$^7$ CFU/ml at room temperature(12$^{\circ}$C ${\sim}$ 30$^{\circ}$C) for 3 days, but were kept less than 2 ${\times}$ 10$^3$ CFU/ml at refrigerator(l0$^{\circ}$C) for 7 days of storage. The sensory quality and acidity of pasteurized milk were gradually changed in proportion to bacterial counts during storage at room temperature and 10$^{\circ}$C for 30 days or 6 months. The standard limit of bacteria in whole market milk was more sensitive than those of sensory and chemical test as standards to determine the unaccepted milk. No significant correlation was found in keeping quality of the milk samples between dark and light exposure at room for 30 days or 6 months. The compositions of fat, solids not fat, protein and lactose in milk samples were not significantly changed according to the storage conditions and time for 30 days or 6 months. The UHT sterilized milk samples(A plant ; 20 samples, B plant ; 110 samples) collected from 2 plants were not changed sensory, chemical and microbiological quality by storage conditions for 6 months, but only one sample from B was detected the bacteria after 60 days of storage. The shelflife of UHT pasteurized milk in this study was a little longer than that reported by previous surveys. Although the shelflife of UHT pasteurized milk made a significant difference among three milk plants, the results indicated that some UHT pasteurized milk in polyethylene coated carton pack could be stored at room temperature for 6 months. The LTLT and HTST pasteurized milk should be sanitarily handled, kept and transported under refrigerated condition(below 7$^{\circ}$C) in order to supply wholesome milk to consumers.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.2
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• pp.113-123
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• 2020

Global climatic change and increasing climatic instability threaten crop productivity. Due to climatic change, drought stress is occurring more frequently in crop fields. In this study, we investigated the effect of treatment with hydrogen peroxide (H₂O₂) before leaf development on the growth and yield of sorghum for minimizing the damage of crops to drought. To assess the effect of H₂O₂ on the growth of sorghum plant, 10 mM H₂O₂ was used to treat sorghum leaves at the 3-leaf stage during growth in field conditions. Plant height, stem diameter, leaf length, and leaf width were increased by 7.6%, 9.6%, 8.3% and 11.5%, respectively. SPAD value, chlorophyll fluorescence (Fv/Fm), photosynthetic rate, stomatal conductance, and transpiration rate were increased by 3.0%, 4.9%, 26.0%, 23.4% and 12.7%, respectively. The amount of H₂O₂ in the leaf tissue of sorghum plant treated with 10 mM H₂O₂ was 0.7% of the applied amount after 1 hour. The level increased to approximately 1.0% after 6 hours. The highest antioxidant activity measured by the Oxygen Radical Absorbance Capacity assay was 847.3 µmol·g^-1 at 6 hour after treatment. However, in the well-watered condition, the concentration of H₂O₂ in the plant treated by the foliar application of H₂O₂ was 227.8 µmol·g^-1 higher than that of the untreated control. H₂O₂ treatment improved all the yield components and yield-related factors. Panicle length, plant dry weight, panicle weight, seed weight per plant, seed weight per unit area, and thousand seed weight were increased by 8.8%, 18.0%, 24.4%, 24.7%, 29.9% and 7.1%, respectively. Proteomic analysis showed that H₂O₂ treatment in sorghum increased the tolerance to drought stress and maintained growth and yield by ameliorating oxidative stress.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.179-183
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• 1980

The efficiency of energy transfer by a population of the farmed pacific oyster, Crassostrea gigas was studied during culture period of 10 months July 1979-April 1980, in Geoje-Hansan Bay near Chungmu City. Energy use by the farmed oyster population was calculated from estimates of half-a-month unit age specific natural mortality rate and data on growth, gonad output, shell organic matter production and respiration. Total mortality during the culture period was estimated approximate $36\%$ from data on survivor individual number per cluster. Growth may be dual consisted of a curved line during the first half culture period (July-November) and a linear line in the later half period (December-April). The first half growth was approximated by the von Bertalanffy growth model; shell height, $SH=6.33\;(1-e^{0.2421(t+0.54)})$, where t is age in half-a-month unit. In the later half growth period shell height was related to t by SH=4.44+0.14t. Dry meat weight (DW) was related to shell height by log $DW=-2.2907+2.589{\cdot}log\;SH,\;(2, and/or log $DW=-5.8153+7.208{\cdot}log\;SH,\;(5. Size specific gonad output (G) as calculated by condition index of before and after the spawning season, was related to shell height by $G=0.0145+(3.95\times10^{-3}{\times}SH^{2.9861})$. Shell organic matter production (SO) was related to shell height by log $SO=-3.1884+2.527{\cdot}1og\;SH$. Size and temperature specific respiration rate (R) as determined in biotron system with controlled temperature, was related to dry meat weight and temperature (T) by log $R=(0.386T-0.5381)+(0.6409-0.0083T){\cdot}log\;DW$. The energy used in metabolism was calculated from size, temperature specific respiration and data on body composition. The calorie contents of oyster meat were estimated by bomb calorimetry based on nitrogen correction. The assimilation efficiency of the oyster estimated directly by a insoluble crude silicate method gave $55.5\%$. From the information presently available by other workers, the assimilation efficiency ranges between $40\%\;and\;70\%$. Twenty seven point four percent of the filtered food material expressed by energy value for oyster population was estimated to have been rejected as pseudofaeces : $17.2\%$ was passed as faeces; $35.04\%$ was respired and lost as heat; $0.38\%$ was bounded up in shell organics; $2.74\%$ was released as gonad output, $2.06\%$ was fell as meat reducing by mortality. The remaining $15.28\%$ was used as meat production. The net efficiency of energy transfer from assimilation to meat production (yield/assimilation) of a farm population of the oyster was estimated to be $28\%$ during culture period July 1979-April 1980. The gross efficiency of energy transfer from ingestion to meat production (yield/food filtered) is probably between $11\%\;and\;20\%$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5877-5884
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• 2014

Recently, abnormally cold weather has been reported more frequently in winter due to the climate change and abnormal weather changes. On the other hand, the heating capacity of a railcar may be not enough to warm the cabin under severe cold climatic conditions, which is one of the reasons for the passengers' complaints about heating. In this study, the effects of ambient temperature and heater power on the cabin temperature was investigated to obtain the minimum ambient temperature for the tested railcar. The test railcar was placed in a large-climatic chamber, and various ambient temperature conditions were simulated. The effects of the heater output were investigated by monitoring the cabin temperature under a range of heater output conditions. The mean cabin temperature was $14.0^{\circ}C$, which was far lower than the required minimum temperature of $18^{\circ}C$, under a $-10^{\circ}C$ ambient temperature condition with the maximum heat power. When the ambient temperature was set to $0^{\circ}C$ and $10^{\circ}C$, the maximum achievable cabin temperature was $26.1^{\circ}C$ and $34.0^{\circ}C$. Through calculations using the interpolation method, the minimum ambient temperature to maintain an $18^{\circ}C$ cabin temperature was $-6.7^{\circ}C$ for this car. The vertical temperature difference was higher with a higher power output and higher ambient temperature. The maximum vertical temperature difference was higher than $10^{\circ}C$ in some cases. However, the horizontal temperature difference vs. low temperature (< $2^{\circ}C$) was independent of the power output and ambient temperature. As a result, it is very important to reduce the vertical temperature difference to achieve good heating performance.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.514-520
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• 2014

In this study, the production potential of alternative coagulant ($Al_2(SO_4)_3$ solution) having the identical coagulation activity with respect to the commercial coagulant was investigated. The raw material of alternative coagulant was a spent catalyst including aluminium (waste activated alumina) generated in the manufacturing process of the polymer. The alternative coagulant was produced through a series of processes: 1) intense heat and grinding, 2) chemical polymerization and substitution with $H_2SO_4$ solution, 3) dissolution and dilution and 4) settling and separation. To determine the optimal operating conditions in the lab-scale autoclave and dissolver, the content of $Al_2O_3$ in alternative coagulant was analyzed according to changes of the purity of sulfuric acid, reaction temperature, injection ratio of sulfuric acid and water in the dissolver. The results showed that the alternative coagulant having the $Al_2O_3$ content of 7~8% was produced under the optimal conditions such as $H_2SO_4$ purity of 50%, reaction temperature of $120^{\circ}C$, injection ratio of $H_2SO_4$ of 5 times and injection ratio of water of 2.3 times in dissolver. In order to evaluate the coagulation activity of the alternative coagulant, the Jar-test was conducted to the effluent in aerobic reactor. As a result, in both cases of Al/P mole of 1.5 and 2.0, the coagulation activity of the alternative coagulant was higher than that of the existing commercial coagulant. When the production costs were compared between the alternative and commercial coagulant through economic analysis, the production cost reduction of about 50% was available in the case of the alternative coagulant. In addition, it was identified that the alternative coagulant could be applied at field wastewater treatment plant without environmental problem through ecological toxicity testing.

• The Journal of the Petrological Society of Korea
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• v.28 no.4
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• pp.251-277
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• 2019

The Gogunsan Archipelago is composed of two island groups; the first group includes Mal-do, Myeong-do, Gwangdae-do, and Bangchuk-do islands consisting of Neoproterozoic rocks, and the second group includes Yami-do, Sinsi-do, Muneo-do, Jangja-do, and Seonyu-do islands consisting of Cretaceous rocks. The first group mainly consists of the Bangchuk formation which can be divided into two layers; the lower layer was more deformed than the upper layer. The former was intruded by mafic and felsic volcanic rocks formed in the volcanic arc tectonic setting 930-890 Ma and the latter was deposited ca. 825-800 Ma. In these islands, large scale folds with east-west fold axes were beautifully formed; the Maldo island fold was designated as natural monument and large scale beautiful chevron fold was developed on the Gwangdae-do island. In addition, there are unique zebra-shaped outcrop formed by a mixing of basic and acidic magma and Independent Gate shaped outcrop formed by coastal erosion. On the other hand, the Yami-do, Sinsi-do, Muneo-do, Jangja-do and Seonyu-do islands consist of 92-91Ma Cretaceous volcanic rocks and, in Sinsi-do island, the Nanshan formation deposited ca. 92 Ma. These Cretaceous volcanic rocks formed by melting of the continental crust by the heat supplied from the uplifting mantle due to the extension caused by a retreat of subducting ocean slab. Yami-do and Sinsi-do islands are composed of rhyolite. In Yami-do island, bands with vertical joint formed by cooling of the bottom part of the lava, are shown. In Sinsi-do island, large-scale vertical joints formed by cooling of lava flow, were developed. The Jangja-bong of Jangja-do island and Mangju-bong of Seonyu-do island are composed of brecciated rhyolite and formed a ring shaped archipelago contributing to the development of marine culture by providing natural harbor condition. They also provide beautiful views including 'Seonyu 8 views' along with other islands. As mentioned above, the Gogunsan archipelago is rich in geoheritages and associated cultural and historical resources, making it worth as a National Geopark.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.59-65
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• 1999

Both the groundwater changes due to different pumping rates and the geochemistry of thermal waters in the Suanbo area are considered in this study. The observation of groundwater level change since 1991 shows that the change is directly correlated with pumping rates of thermal waters and reveals the retardation of ca. 5 weeks after pumping. The hydrogeological aquifer in the area is under reducing condition. The thermal waters are of Na-HCO$_3$ type. and are alkaline (pH=8.5∼8.7) with low TDS values (274∼284 mg/l) and high concentrations of Na (68∼72 mg/l). F (6.4∼8.9 mg/l), and HCO$_3$(136∼146 mg/l). Oxygen and hydrogen isotope ratios of thermal water indicate a meteoric water origin. The activities of Rn-222 and Ra-226 in both thermal water and local groundwater were determined to delineate possible geochemical controls on the Rn-222 and Ra-226. The Rn-222 concentrations are several orders of magnitude greater than the Ra-226 concentrations. The concentrations of Rn-222 range from 190 to 7.490 pCi/1 with an average of 2,522 pCil/l. and those of Ra-226 average 0.32 pCi/1 with the range from 0.25 to 0.42 pCi/1. The concentrations of Rn-222 and Ra-226 are inversely correlated with EC and alkalinity. The pH it positively correlated with Ra-226. The correlation between Rn-222 and Ra-226 is poor. Thermal waters in the study area are produced from highly fractured phyllite. The thermal water qualify. CSAMT (controled-source audiofrequency magnetotelluric) prospecting, and petrological evidences, however, indicate that the heat is possibly transmitted through deep normal faults reaching a deep granite batholith, and the phyllite acts only as a groundwater pathway.