• Journal of Life Science
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• v.26 no.1
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• pp.68-74
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• 2016

Perchlorate (ClO₄⁻) is an emerging pollutant detected in surface water, soil, and groundwater. Previous studies provided experimental evidence of autotrophic ClO₄⁻ removal with elemental sulfur (S⁰) particles and activated sludge, which are inexpensive and easily available, respectively. In addition, ClO₄⁻ removal efficiency was shown to increase when an enrichment culture was used as an inoculum instead of activated sludge. PCR-DGGE was employed in the present study to investigate the microbial community in the enrichment culture that removed ClO₄⁻ autotrophically. Microorganisms in the enrichment culture showed 99.71% or more ClO₄⁻ removal efficiency after a 7-day incubation when the initial concentration was approximately 120 mg ClO₄⁻/l. Genomic DNA was isolated from the enriched culture and its inoculum (activated sludge), and used for PCR-DGGE analysis of 16S rRNA genes. Microbial compositions of the enrichment culture and the activated sludge were different, as determined by their different DGGE profiles. The difference in DGGE banding patterns suggests that environmental conditions of the enrichment culture caused a change in the microbial community composition of the inoculated activated sludge. Dominant DGGE bands in the enrichment culture sample were affiliated with the classes β-Proteobacteria, Bacteroidetes, and Spirochaetes. Further investigation is warranted to reveal the metabolic roles of the dominant populations in the ClO₄⁻ degradation process, along with their isolation.

• The Korean Journal of Air & Space Law and Policy
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• v.28 no.2
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• pp.63-96
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• 2013

Recently, U.S. Department of Transportation (DOT) expanded the "Enhancing Airline Passenger Protections" on August 23, 2011 and October 24, 2011. The Rule regulates tarmac delays, denied boarding compensation, customer service plans, and fare advertising. The adopted rule is to protect passengers by improving passenger service requirements on U.S. national or domestic carriers and foreign air carriers as well. The major issues are as follows: First, regarding to so called Tarmac Delay, carriers must establish a Tarmac Delay Contingency Plan setting forth the number of hours the carrier will permit an aircraft to remain on the tarmac at U.S. airports before allowing passengers to deplane. Carriers also must provide passengers with food and water in the event the aircraft remains on the tarmac for two or more hours and must provide operable lavatories and medical attention while the aircraft remains on the tarmac, irrespective of the length of the delay. Carriers also must create and retain records regarding tarmac delays lasting more than three hours. Also they need to update passengers every 30 minutes during a tarmac delay of the status of the flight and the reason for the delay, allow passengers to deplane if the aircraft is at the gate or another disembarkation area with the door open. Second, carriers now must adopt a "Customer Service Plan" that addresses offering customers the lowest fares available, notifying customers about delays, cancellations, and diversions; timely delivery of baggage; accommodating passengers' needs during tarmac delays and in "bumping cases"; and ensuring quality customer service. Third, the new regulations also increase minimum denied boarding compensation limits to $650 / $1,300 or 200% / 400% of the fare, whichever is less. Last, the DOT also has modified its policies related to enforcement of Rules pertaining to full fare advertising. The Rule states that the advertised price for air transportation must be the entire price to be paid by the customer. Similarly, Korea revised the passenger protection clauses within Aviation Act. However, it seems to be required to include various more issues such as Tarmac Delay, oversales of air tickets, involuntary denied boarding passengers, advertisements, etc.

• Journal of Korean Society of Forest Science
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• v.77 no.3
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• pp.259-268
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• 1988

For the purpose of examining the effects of simulated acid rain on nutrient contents of plant tissues in Pintos densiflora seedlings and Forsythia koreana rooted cuttings, the experimental design of randomized block arrangement with three replications was implemented in the experimental field of Yesan National Agricultural Junior College. One-year-old Pinus densiflora seedlings and Forsythia koreana cuttings were planted in the pots filled the mixed soils(nursery soil : forest soil of siliceous sandy loam=1 : 1 v/v) in the early spring of 1986. The regime of artificial acid rain, in terms of spray frequency per month and spray amount at single treatment per plot, was simulated on the basis of climatological data averaged from 30 years records. Simulated acid rain(pH 2.0, pH 4.0, and pH 5.5 as control) containing sulfuric and nutric acid in the ratio of 3 : 2(chemical equivalant basis) diluted with ground water were treated on the experimental plants under condition of cutting off the natural precipitation with vinyl tunnel, during the growing season(May 1 to August 31) in 1986. The results obtained in this study were as follow : (1) As for the nitrogen contents in plant tissues, P. densiflora increased significantly in one-year-old stembranch and root tissues, and F. koreana increased significantly in leaf and root tissues, as the pH levels of acid rain decreased. (2) The available phosphate contents in root tissues of P. densiflora, and in leaf and root tissues of F. koreana were significantly decreased, as the pH levels of acid rain decreased. (3) $K_2O$, CaO and MgO contents in plant tissues were significantly decreased in the both species as the pH levels decreased. And the effects of acid rain on F. koreana were higher than those of P. densiflora. (4) Sulfur contents of plant tissues in the both species were increased at pH 2.0 treatment. There were significant differences among three acid rain treatments in leaf and root tissues of P. densiflora, and in all parts of F. koreana. (5) In the effects of simulated acid rain on the both species and the tested soils, in general, F. koreana revealed higher sensitiveness than P. densiflora, and the lower pH levels of simulated acid rain were treated, the more sharp reaction was showed.

• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.1-8
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• 2020

Centrifugal pump is a facility that transfers energy to fluid through centrifugal force, which is usually generated by rotating the impeller at high speed, and is a major process facility used in many LNG production bases such as vaporization seawater pump, industrial water and fire extinguishing pump using seawater. to be. Currently, pumps in LNG plant sites are subject to operating conditions that vary depending on the amount of supply desired by the customer for a long period of time. Pumps in particular occupy a large part of the consumption strategy at the plant site, and if the optimum operation condition is not available, it can incur enormous energy loss in long term plant operation. In order to solve this problem, it is necessary to identify the performance deterioration factor through the flow analysis and the result analysis according to the fluctuations of the pump's operating conditions and to determine the optimal operation efficiency. In order to evaluate operation efficiency through experimental techniques, considerable time and cost are incurred, such as on-site operating conditions and manufacturing of experimental equipment. If the performance of the pump is not suitable for the site, and the performance of the pump needs to be reduced, a method of changing the rotation speed or using a special liquid containing high viscosity or solids is used. Especially, in order to prevent disruptions in the operation of LNG production bases, a technology is required to satisfy the required performance conditions by processing the existing impeller of the pump within a short time. Therefore, in this study, the rotation difference of the pump was applied to the ANSYS CFX program by applying the modified 3D modeling shape. In addition, the results obtained from the flow analysis and the curve fitting toolbox of the MATLAB program were analyzed numerically to verify the outer diameter correction theory.

• KSBB Journal
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• v.19 no.2
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• pp.93-97
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• 2004

We investigate the effect of enzyme pretreatment using protease, carbohydrase, and lipase on improvement of sludge treatment efficiency by measuring SCOD and TCOD. The enzyme-pretreatment increases SCOD of excess sludge. In addition, the amount of sludge reduction during digestion, in terms of SCOD and TCOD, are enhanced by enzyme-pretreatment. Among pretense, carbohydrase, and lipase, pretense showed the best enhancement of the sludge treatment efficiency. Sludge digestion followed by ozone and enzyme treatments showed more effective sludge treatment when compared with ozone treatment alone. Therefore, we expect that enzyme pretreatment can be used as a useful tool for enhancing the sludge treatment efficiency.

• Journal of Life Science
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• v.27 no.9
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• pp.1064-1069
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• 2017

This study compared the cytotoxic effect of extracts from four different sea bream species (Pagrus major, Acanthopagus schlegeli, Oplegnathus fasciatus, and Girella punctata) in human cancer cell lines. Cytotoxic activity against the growth of human gastric adenocarcinoma (AGS) and HT-29 human colon cancer cell lines was determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Treatment with acetone/methylene chloride (A+M) and methanol (MeOH) extracts from the four sea bream species dose-dependently increased cytotoxicity against the growth of AGS and HT-29 cancer cells (p < 0.05). As shown by a cell viability assay, treatment with A+M and MeOH extracts from red sea bream (P. major) had the highest cytotoxic effect (p < 0.05) among the sea bream species. The IC50 values of an 85% aqueous methanol (85% aq. MeOH) fraction from red sea bream (P. major) against AGS and HT-29 cancer cells was 0.33 and 1.58 mg/ml, respectively, suggesting that the 85% aq. MeOH fraction had the highest cytotoxic effect among the fractions (p < 0.05). Our results demonstrate that four different sea bream species exhibited cytotoxic activity, as well as high-quality amino acids and fatty acids. Among the sea bream species, red sea bream (P. major) showed the greatest cytotoxic effect. The results could be used to improve nutrition information available to consumers.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.336-342
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• 2012

Inorganic materials were commonly used as container media in domestic plant factories. Objective of this research was to secure the information in soil physical and chemical properties of inorganic materials such as vermiculites and perlites. To achieve this, 12 gold and silver vermiculites from China, Zimbabwe, and South Africa and 5 perlites from China were collected based on the marketing grades (MG) in particle sizes and analyzed for determination of their characteristics. The percentage of particles larger than $710{\mu}m$, in China perlite MG 3~5 mm, China silver vermiculites MG > 8 mm and MG 3~8 mm were 99.9%, 99.8%, and 99.7%, respectively, which were much higher than 28.4% in China gold vermiculite MG 0.3~1.0 mm, 14.0% in perlite MG < 1.0 mm, and 12.6% of Zimbabwe silver vermiculite MG < 1.0 mm. The container capacities of perlite MG < 1.0 mm and South Africa silver vermiculite MG 0.25~1.0 mm were 72.0% and 71.1%, respectively. The air space in China silver vermiculite MG 3~8 mm was 49.3% which was higher than other materials tested. However, the China gold and silver vermiculites MG 0.3~1 mm had 3.5% and 2.4% in air space indicating that possible problems could occur in soil aeration when they are used for container media. The percentage of easily available and buffering water of China gold vermiculite MG 0.3~1 mm and perlite MG < 1.0 mm were the highest among test materials. The ranges of pH and electrical conductivity were 6.36 to 10.7 and 0.032 to $0.393dS{\cdot}m^{-1}$ in vermiculites and 7.78 to 8.62 and 0.030 to $0.041dS{\cdot}m^{-1}$ in perlite, respectively. The cation exchange capacity of China silver vermiculite MG 0.3~1 mm were $14.7cmol{\cdot}kg^{-1}$ that was 10 times as high as $0.34cmol{\cdot}kg^{-1}$ in perlite MG 1~2.5 mm. The vermiculites had the higher contents of exchangeable cations such as Ca, K, and Na, than those of perlites.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.881-897
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• 2019

We reconstructed and digitized the National Institute of Fisheries Science (NIFS) Serial Oceanographic observations (NSO) and Coastal Oceanographic observations (NCO) data attained prior to 1961 through historical oceanographic observation data rescue projects. Increasing trends of long-term sea surface temperature (SST) were shown from the NSO data of 21 available stations for the past 80 to 92 years. In general agreement with previous research results used in the data of the past 50 years, we calculated the rate of temperature rise. As a result of analyzing the spatial distribution of SST change rate in the Korean of shore region using selected oceanographic data, the West Sea and South Sea showed a higher tendency of temperature rise in the offshore area than in the coastal area. However, unlike the results of previous studies, the East Sea (Gangwon Line and Ulsan Line) showed a lower water temperature rise than the coastal stations. Annual fluctuations of NCO's SST data from 1989 to 1998 for three stations representing the East Sea, South Sea, and West Sea, (Jumunjin, Geomundo and Budo, respectively) revealed that the East Sea showed the highest SST increase for the 10 years. The increases were 1.63 ℃ at Jumunjin, 1.16 ℃ at Geomundo, and 0.79 ℃ at Budo. As a result of the investigation, it can be concluded that SST is repeatedly rising and falling with a period of 3 ~ 6 years. Especially, since the 1980s, most of the stations show positive anomalies of SST. Lastly, to understand ocean_atmosphere interactions, we analyzed the correlations between SST of the NCO stations and air temperature around them and the results were 0.76 for the South Sea (Geomundo), 0.34 for the West Sea (Budo), and 0.32 for the East Sea (Jumunjin) with the highest correlation in the South Sea.

• Economic and Environmental Geology
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• v.44 no.3
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• pp.217-228
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• 2011

The feasibility study for the stabilization process using 5 amendments was performed to quantify As-immobilization efficiency in farmland soils around Samkwang abandoned mine, Korea. For the batch experiments, with 2% and 3% of granular lime(2-5 mm in diameter), leaching concentration of As from the soil decreased by 86% and 95% respectively, compared to that without the amendment. When 5% and 10% of granular limestone was added in the soil, As concentration decreased by 82% and 95%, showing that lime and limestone has a great capability to immobilize As in the soil. From the results of batch experiments, continuous column(15 cm in dimeter and 100 cm in length) tests using granular lime and limestone as amendments was performed. Without the amendment, As concentration from the effluent of the column ranged from 167 ${\mu}g$/L to 845 ${\mu}g$/L, which were higher than Korea Drinking Water Limit(50 ${\mu}g$/L). However, only with 1% and 2% of lime, As concentration from the column dramatically decreased by 97% for 9 years rainfall and maintained below 50 ${\mu}g$/L. With 5% of limestone and the mixed amendment(1% of lime + 2% of limestone), more than 95% diminution of As leaching from the column occurred within I year rainfall and maintained below 20 ${\mu}g$/L, suggesting that the capability of limestone to immobilize As in the farmland soil was outstanding and similar to that of lime. Results of experiments suggested that As stabilization process using limestone could be more available to immobilize As from the soil than using lime because of low pH increase and thus less harmful side effect.

• Korean Journal of Environmental Agriculture
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• v.21 no.1
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• pp.50-56
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• 2002

This experiment was carried out to obtain some information about overwintering, physiological and ecological characteristics of apple snails. Another purpose of this experiment was to characterize an appetite for rice plants by apple snails and to elucidate their choice of fresh green ones (vegetables, some other crops, weeds in rice fields). The freshwater snails were found with higher population at sites abundant organic compounds such as plant debris and at regions with high temperature. They also prefer calcium-rich water. This is a naturally occurring process. Apple snails were exceptionally veil-adapted to the south regions of Korea, especially Janghang, Jangseong and Haenam, even if the temperature of winter season is cold below 0$^{\circ}C$. Apple snails were not very selective in their food choice and eat almost everything available in their environment. A snail have something called a radula in its mouth for grinding up its food. A apple snail also chews on fruits and young succulent plant barks. In case of reproduction. apple snails deposit about 157$\sim$784 (average of 321 eggs) milky white to pale orange colored eggs above the waterline. In approximately every 22.4 seconds a new egg appears. The total time needed to deposit a egg mass varies from 58 minutes$\sim$4 hours 13 minutes. Apple snails reproduct actively from May to June and from September to October. An appetite of apple snails for rice plants was the different depending on their size and glowing stage for rice plants. Apple snails had a great appetite of rice plants as well as dropwort, tomato, cabbage, radish, aquatic plants etc. They preferred to eat young rice plants and drastically quit eating rice plants of over 40 cm in height. Thus considering the food preference of apple snail for various plants including rice, they were thought to be a potentially strong predator in fields, especially, at regions with warmer winter.