• Fisheries and Aquatic Sciences
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• v.18 no.2
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• pp.123-130
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• 2015

Seaweed Sargassum horneri extracts were obtained using supercritical carbon dioxide ($SC-CO_2$) and different solvents. $SC-CO_2$ was kept at a temperature of $45^{\circ}C$ and pressure of 250 bar. The flow rate of $CO_2$ (27 g/min) was constant during the entire 2-h extraction period, and ethanol was used as a cosolvent. Six different solvents [acetone, hexane, methanol, ethanol, acetone mix methanol (7:3), and hexane mix ethanol (9:1)] were used for extraction and agitated by magnetic stirring (250 rpm) in the dark at $25^{\circ}C$ for 20 h; the ratio of material to solvent was 1:10 (w/v). Antioxidant properties of S. horneri extracted using $SC-CO_2$ with ethanol and different solvents have shown good activity. The highest activity belongs to $SC-CO_2$ with ethanol extracted oil, showing DPPH, ABTS, total phenolic content, and total flavonoid levels of $68.38{\pm}1.21%$, $83.51{\pm}1.25%$, $0.64{\pm}0.02mg/g$, and $5.57{\pm}0.05mg/g$, respectively. The S. horneri extracts showed a significant correlation between the antioxidant activity and phenolic content. Based on these results, the $SC-CO_2$ extract (ethanol) of the seaweed extract from brown seaweed may be a valuable antioxidant source.

• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.39-45
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• 2017

The LNG storage tank as core facility of LNG industry is mainly composed of the inner tank of nikel 9% steel and the outer tank of prestressed concrete. To respond proactively increased risk of structure performance deterioration due to fatigue of the inner tank and durability reduction of the outer tank, life evaluation program for LNG storage tank is needed. In this study, life evaluation program for LNG storage tank was developed to assess fatigue of the inner tank and durability(carbonation and chloride attack) of the outer tank. By defining the main three scenarios in the inner tank, the fatigue life analysis is conducted from structural analysis and Miner's damage rule. Carbonation progress of the outer tank is predicted according to thickness of cover concrete by using carbon dioxide contents and data of penetration depth. To consider a variety of input conditions and a reliability in results of chloride attack, the evaluation of choride attack for the outer tank is constructed through Life-365 program of open source.

• Journal of Hydrogen and New Energy
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• v.30 no.1
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• pp.14-20
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• 2019

The power to gas (P2G) is one of the energy storage technologies that can increase the storage period and storage capacity compared to the existing battery type. One of P2G technologies produces hydrogen by decomposing water from renewable energy (electricity) and the other produces $CH_4$ by reacting hydrogen with $CO_2$. The objective of this study is the reaction of $CO_2$ methanation which synthesized methane by reacting carbon dioxide and hydrogen. The effect of $CO_2$ conversion and $CH_4$ selectivity on reaction temperature, pressure, and methane contents over 40% Ni catalyst was mainly investigated throughout this study. As a result, the activity of this catalyst appeared to be the highest in $CH_4$ yield at around $400^{\circ}C$ and the selectivity of $CH_4$ increased with increasing reaction pressure. The methane content was not significantly influenced below 3% of all componets. As the space velocity increases from 10,000 to 30,000/hr, the $CO_2$ conversion rate tends to decrease.

• Journal of the Korean Society of Food Culture
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• v.20 no.4
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• pp.468-475
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• 2005

To determine the effect of different fermentation level on the quality of Nabak Kimchi during storage, this study was carried by analysing the result of physico-chemical properties, microbiological characteristics and sensory evaluation of Nabak Kimchi stored up to 24 days. For the physico-chemical properties, pH, total acidity, reducing sugar, carbon dioxide contents, color values were investigated while for the microbiological characteristics, total microbial counts and lactic acid bacteria were studied. Nabak Kimchi products were fermented at six different level of temperature and time and stored in Kimchi refrigerator at $4^{\circ}C$ for 24 days. As the storage period increased, the pH values of LF15, SF25 and LF25 decreased rapidly after initial fermentation and the pH values of SF4, LF4 and SF15 increased slightly in the beginning and then decreased. total acidity increased as storage period proceeded. the amount of reducing sugar was 4.92mg/ml before fermentation and increased significantly and reached its maximum values then decreased. lightness and redness of Nabak Kimchi decreased as storage period became longer, but yellow of Nabak Kimchi increased during storage. Total microbial counts of SF25 and LF25 reached to the highest at the 6th day and total microbial counts of LF15 reached to the highest at the 12th day and then significantly decreased. However, total microbial counts of SF4, LF4 and SF15 continuously increased up to the 24th day. The number of lactic acid bacteria was similar to the phase of the change of total microbial counts.

• Korean Journal of Food Science and Technology
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• v.41 no.1
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• pp.37-41
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• 2009

In this study, supercritical carbon dioxide extraction (SFE) was utilized for the extraction of tocotrienol from grape seeds. The optimal conditions for vitamin E and tocotrienol extraction were determined via response surface methodology (RSM). Central composite design was utilized to assess the effects of oven temperature (30-$50^{\circ}C$, X1), operating pressure (17-25 MPa, X2), and extraction time (1-5 hr, X3) of supercritical fluid extraction. Vitamin E and tocotrienol contents were 8.65 mg/100 g and 7.88 mg/100 g at $40^{\circ}C$, 20MPa and 5 hr, respectively. The predicted extraction condition was validated via actual experimentation. The predicted extraction conditions were $40^{\circ}C$, 3.8 hr, and 20.7MPa. The vitamin E and tocotrienol contents under these conditions were 8.20 mg/100 g and 7.42 mg/100 g, respectively. The vitamin E and tocotrienol contents of solvent extraction with hexane were 8.18 mg/100 g and 7.24 mg/100 g, respectively.

• 보존과학연구
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• s.25
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• pp.119-132
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• 2004

Annals of the Joseon Dynasty is the authentic record of the historical facts and events taken place throughout the entire period of 472 years(25 generations, 1392~1863)described in a chronological order. The tremendous volume of the records contains the factual events taken place in almost all the fields of the Joseon Dynasty ranging from politics, economy to history of the dynasty. Not only because of its affluent contents but also with the precision of its records, it was designated as the National Treasure No. 151 in1973 by the Korean government and also registered as the Memory of the World by UNESCO in October 1997.This study is to report a exhaustive investigation results on the conservation state of annals of the Joseon Dynasty, especially Mt. Jeongjoksan edition, under the storage of the Kyujanggak in order to obtain the current condition, and thereby to estimate the any deterioration of the waxed volumes in the future. According to results of the investigation, we are going to verify damage causes of annals of the Joseon Dynasty, and to consider scientific conservation methods for the permanent preservation of invaluable cultural heritage. The major problem with the preservation of annals has arisen particularly from the deterioration of the waxed volumes of the Mt. Jeongjoksan edition. In order to provide for the counter measures for this problem, we have conducted twice investigations(first :1998~1999, second : 2003) to the internal and external conditions of waxed volumes(Annals of King Taejo~Annals of King Myeongjong).The result of the investigation has indicated that the paper quality of the some of the waxed volumes (Annals of King Taejong~Annals of King Sejong) is cracked and folded and the pages are imbedded to each other due to the hardened or congealed wax on the paper. Some of the pages are even getting moldy. And in order to detect as to whether“ there has been any deterioration progressed to the waxed books in the modern storage facility of the Kyujanggak equipped with constant temperature and humidity condition, the first investigation(1998~1999) and the second investigation(2003) have recorded the values of acidity, whiteness and moisture rate of the waxed paper, reporting an observation that there has been no difference on the measuring items. This indicates that no virtual deterioration has been progressed so far to the waxed volumes preserved in the Kyujanggak. Also, except for the causes of deterioration to the paper by insects and microorganisms, the major cause for the paper damage seems to the change of moisture of the paper caused from the alteration of the temperature and humidity of the storage environment. With this understanding in mind, we have conducted an environmental investigation on the three selected points of the storage in the aspects of the temperature, humidity, air current, $CO_2$,HCHO, and $SO_2$.It has been observed that the temperature stood at $16.9^{\circ}C~20.2^{\circ}C$ and the humidity was stable between 53%~56% during the period of the investigation. The concentration of the carbon monoxide and carbon dioxide of the storage were very similar to those in the air. These data lead to presume that there is no problem in the aspect of carbon oxidization. But the concentration of sulfur dioxide, hydrogen sulfide and formaldehyde of the storage were detected a little higher than those of standard. Therefore, we consider that it is necessary to ventilate the internal air of the store room by means of operating air purification devices.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.79-86
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• 2018

BACKGROUND: Chinese cabbage biosynthesizes various phytochemicals including carotenoids and glucosinolates. Environmental stress has a major effect on the growth and yields of vegetables, and can significantly affect nutritionally important phytochemicals. Phytochemicals of plants are influenced by light, temperature, carbon dioxide, and growing conditions. The aim of this study was to investigate the effect of various light sources on carotenoid and glucosinolate contents in Chinese cabbage. METHODS AND RESULTS: [Experiment I] Set the control (field control, FC) on the ground. Using acrylic sunlight, experiments were set up transparency box (field transparency, FT), red box (field red, FR) and blue box (field blue, FB). [Experiment II] Set the control (chamber control, CC) in the greenhouse. Using plant growth chamber with artificial light, experiments were set up LED red (chamber red, CR), LED blue (chamber blue, CB), LED mixed red+blue (chamber red+blue, CRB) and fluorescent (chamber fluorescent, CF). After plant growth, Chinese cabbage was harvested at 110 days after sowing (DAS). The status of plants growth (leaf length, width, fresh weight etc.) was immediately investigated. Carotenoid and GSL contents were analyzed by HPLC. [Experiment I] Results documented that the ranges of total carotenoid contents were 25.39 ~ 58.80 mg/kg dry wt for lutein, 0.84~ 4.22 mg/kg dry wt for zeaxanthin, and 3.85~18.71 mg/kg dry wt for ${\beta}$-carotene. Lutein was the highest for the content and the largest for the variation as well. [Experiment II] Results documented that the ranges of total carotenoid contents were 24.66~137.96 for lutein, 2.51~20.65 for zeaxanthin, and 8.40~49.80 mg/kg dry wt for ${\beta}$-carotene. The total carotenoid contents of CR (156.62) and CB (115.90) were 1.6~2.3 times larger than the other treatments, and ${\beta}$-carotene content was about twice as high as that of the other treatments on the CR (38.74 mg/kg dry wt.). [Experiment I] Total GSL content was the highest in FT (19.76) that was higher 1.7 times than the lowest treatment ($11.39{\mu}mol/g\;dry\;wt$.). [Experiment II] The total content of GSL was highest in CRB (4.19) and lowest in CF ($2.88{\mu}mol/g\;dry\;wt$.). In the CRB, total GSL contents ($4.19{\mu}mol/g\;dry\;wt$.) was the highest. CONCLUSION: Total and individual carotenoid and GSL contents in Chinese cabbage show significant differences under different light sources. Red and blue lights contribute to significant carotenoids expression and antioxidant activity for nutrition and health benefits. These results concluded that the introduction of varying lights affected the synthesis of important nutrient compounds in Chinese cabbage. It is predicted that the application of good light source enhances the accumulation of functional compounds.

• The Journal of the Korea Contents Association
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• v.17 no.4
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• pp.1-11
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• 2017

Interest in all kinds of renewable energies has been highly increased while the micro-small-hydro power(MSHP) development has shown relatively slowly growth because of the negative public recognition about dam site development. It is, however, announced that the micro-SHP shows higher energy conversion efficiency compared to other renewable energies and does not emit any carbon dioxide. Thus, it is concerned about the development and application of micro-SHP as an alternative energy. In this study, the application for Android was exploited with Eclipse to visualize readily the potential realizable amount of hydropower by micro-SHP. With this application, we can select the region from the map, obtain the design discharge of the selected site was calculated with HEC-HMS, presented by U.S. Army of Corp. and perform the simply economic analysis in sequence. Yeongwol in Gangwon-do Province, Korea was chosen as the target area since historically abundant precipitation was found and it is possible to obtain fundamental data from WAMIS. Results from this study could be expanded the whole region of Korea. Also, the initial investment cost would be reduced if the location for micro-SHP would be determined properly, because this application can help us easily select and examine the potential micro-SHP sites without on-the-spot visit.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.542-549
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• 2015

The bioelectrochemical anaerobic digestion for sewage sludge was attempted at different applied voltages ranged from 0.2 V to 0.4 V. At 0.3 V of the applied voltage, pH and VFAs were at 7.32 and 760 mg COD/L, respectively, which were quite stable. The methane production rate was $1.32L\;CH_4/L.d$, and the methane content in biogas was 73.8%, indicating that the performance of the bioelectrochemical anaerobic digestion could be considerably improved by applying a low voltage. At 0.4 V of the applied voltage, however, the contents of the minor VFA components including formic acid and propionic acid were increased. The methane production rate was reduced to $1.24L\;CH_4/L.d$ and the biogas methane content was also reduced to 72.4%. At 0.2 V of the applied voltage, the pH was decreased to 6.3, and VFAs was accumulated to 5,684 mg COD/L. The contents of propionic acid and butyric acid in the VFAs were considerably increased, The performances in terms of the methane production rate and the biogas methane content were deteriorated. The poor performance of the bioelectrochemical reactor at 0.2 V of the applied voltage was ascribed to the thermodynamic potential lack for the driving of the carbon dioxide reduction into methane at cathode.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.417-422
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• 1998

This study was performed to obtain information about the extraction conditions of lipids from microalgae, Spirulina platensis, using supercritical fluid $CO_2$. Regardless of extraction temperature conditions, the extracted lipid contents increased as pressure increased, but decreased at 8500 psi on each temperature. The highest yield of extracted lipid content showed in the condition of 5500psi at $50^{\circ}C$, and extracted lipid content was about $20\%$. In same pressure the contents of C18 : 2 and C20 : 0 increased as temperature increased, but fatty acids composition were $60\~75\%$ saturated, $12\~20\%$ monounsaturated and $13\~31\%$ polyunsaturated regardless of extraction conditions. The C18 : 3 was only detected in the condition of 5500psi at $50^{\circ}C$ but the content was very little.