• Journal of Life Science
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• v.20 no.11
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• pp.1718-1724
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• 2010

Bioactive and chemical properties of silkworm powder (SP) degradation by fruit extract containing the proteolytic enzymes of kiwifruit, papaya, pineapple and pear were investigated. Silkworm powder was incubated with extracts from each fruit at $60^{\circ}C$ for 24 hr. Protein content was slightly higher in the SP treated with fruit extract than that in the control SP. Major minerals were K, Ca, Mg, and Zn. Major fatty acids were linolenic acid, oleic acid, and palmitic acid. When total protein patterns were analyzed by SDS-polyacrylamide gel electrophoresis (PAGE), silkworm protein was strongly degraded by the treatment of fruit extract from pineapple, papaya, and pear, but little silkworm degradation was observed in kiwifruit extract treatment. Fibriolytic activity was only detected in the SP by the fruit extract treatments from papaya and pear. DPPH radical scavenging activity was slightly stronger in the SP treated with fruit extract than that in silkworm powder. However, all these samples exhibiteda relatively low activity compared with the butylated hydroxytoluene (BHT). These results may provide the basic data for understanding the biological activities and chemical characteristics of SP treated with fruit extract for development of functional foods.

• Journal of IKEEE
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• v.24 no.1
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• pp.347-353
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• 2020

In this paper, the durability of an electromagnetic metamaterial absorber is verified in a temperature varying condition mimicking a maritime environment for the purpose of applying it to reduce the radar cross section of an integrated mast of the next-generation destroyer. To validate the durability, the reflectance of the electromagnetic metamaterial absorber was measured after storing it in a chamber that can control the temperature according to Procedure I of Method 501.7 included in MIL-STD-810H. Before and after the environmental test, both of the measured reflectances were retained less than -10 dB over the X band, that can guarantee the stealth functionality.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.12-19
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• 2015

In this paper, temporal variations of acoustic transmission loss (TL) affected by internal tide are studied by computer simulation using oceanic data measured in the southern sea of Jeju Island in summer. Temperature was measured with depth (bottom depth are nearly 80 m) in two sites near Seogwipo coast every one hour for 25 hours during July 27 and 28, 2009. The periodic fluctuation of temperature due to the internal tide was observed and its vertical displacement was more than 10 m. In order to investigate temporal variation of TL by internal tide, acoustic propagation between two measurement sites (3.8 km distance) was simulated with a source depth of 10 m. TL variation for 1/3 octave band of 100 Hz center frequency highly coincided with tidal period but more complex variation with indistinct tidal period was observed for 1 kHz. Maximun standard deviation of TL variation was 4.2 dB for 100 Hz at 2.8 km distance from a source and it was 3.7 dB for 1 kHz. The tidal variation was also shown in detection range and its maximum variance was less than 1 km. These results imply that temporal variation of TL should be considered for acoustic researches at the southern sea of Jeju Island.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.42-50
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• 2023

In this study, hexagonal ferrite powder with chemical formula SrZn_2-xCo_xFe₁₆O₂₇ was synthesized by a solid-state reaction method and its electromagnetic (EM) wave absorption characteristics were evaluated in the frequency range of 0.1-18 GHz with absorber thickness range of 0 - 10 mm. Reflection loss (RL) affecting electromagnetic wave absorption performance was calculated based on the transmission line theory using measured complex permeabilities and permittivities. RL spectra were also directly measured for some samples. They were well matched with calculated results. High-frequency complex permeability characteristics were changed gradually according to the amount of Co substitution (x). The EM wave absorption frequency band could be tuned accordingly. Hexaferrite samples with x = 1.0, 1.25, and 1.5 exhibited remarkable maximum electromagnetic wave absorption performances with minimum RL (RL_min) lowered than -50 dB. They also showed a very broad frequency band (Δf > 10 GHz) in which more than 90% of the EM wave energy absorption occurred (RL ≤ -10 dB).

• Korean Journal of Food Science and Technology
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• v.15 no.2
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• pp.128-132
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• 1983

The apple seed contained 25.96% of crude fat and 37.62% of crude protein. The lipid fractions obtained by cilicic column chromatography were mainly composed of about 93.52% neutral lipid, whereas compound lipid was only 6.48% level. Among the neutral lipid separated by thin layer chromatography, triglyceride was 92.17%, sterol ester, sterol, diglyceride and free fatty acid were 3.53, 2.25, 1.44 and 0.56, respectively. The predominent fatty acids of total and neutral lipids were linoleic acid (59.79-69.37%) and oleic acid (20.04-29.82%), but those of glycolipid and phojspholipid were linoleic acid (29.20-36.04%). The major fatty acids of triglyceride separated from neutral lipid were oleic acid (44.31%), linoleic acid (36.66%) and palmitic acid (12.48%). The salt soluble protein of apple seed was highly dispersible in 0.02M sodium phosphate buffer containing about 1.0M $MgSO_4$, and the extractability of seed protein was 37%, Glutamic acid was the major amino acid in salt soluble protein, followed by arginine and aspartic acid. The eletrophoretic analysis showed three bands in apple seed protein, and the collection rate of the main protein fraction purified by Sephadex G-100 and G-200 was 76.6%. Glutamic acid, aspartic acid and arginine were the major amino acids of the main apple seed protein. The molecular weight for the main protein of the apple seed was estimated to be 45,000.

• Korean Journal of Food Science and Technology
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• v.14 no.3
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• pp.250-256
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• 1982

A series of studies were conducted to find out the possibility of utilizing grape seed as resources of food fats and proteins, and the results of the studies are as follows: The grape seed contained 25.1%, of crude fat and 12.0% of crude protein. The lipid, fractions obtained by silicic acid column chromatography were mainly composed of about 95.5% neutral lipid, whereas compound lipid was only 4.5% level. Among the neutral lipid by thin layer chromatography, triglyceride was 91.89%, sterol ester, sterol, diglyceride and free fatty acid were 3.24%, 2.87%, 1.20% and 0.80%, respectively The predominant fatty acids of total and neutral lipids were linoleic acid $(69.72{\sim}71.72%)$ and oleic acid $18.09{\sim}19.46%)$, but those of glycolipid and phospolipid were linoleic acid $(31.49{\sim}38.18%)$, oleic acid $(20.20{\sim}35.27%)$ and palmitic acid $(26.80{\sim}39.98%)$. The major fatty acids of triglyceride separated from neutral lipid were oleic acid (43.08%), linoleic acid (38.42%) and palmitic acid (11.60%). The salt soluble protein of grape seed was highly dispersible in 0.02M sodium phosphate buffer containing about 1.0M $MgSO_4$, and the extractability of seed protein was 31%. Glutamic acid was the major amino acid in salt soluble protein, followed by arginine and aspartic acid. The electrophoretic analysis showed 3 bands in grape seed protein, and the collection rate of the main protein fraction purified by Sephadex G-100 and G-200 was 82%. Glutamic acid, aspartic acid and arginine were the major amino acids of the main grape seed protein. The molecular weight for the main protein of the grape seed was estimated to be 81,000.

• Pediatric Infection and Vaccine
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• v.16 no.2
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• pp.175-182
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• 2009

Purpose : A number of countries have experienced an increase in pertussis during the past decade. In particular, there has been an increase in the incidence rate among adolescents and adults. To learn more about the current epidemiology of pertussis, we studied the prevalence and clinical characteristics of pertussis in children in Cheonan, South Korea. Methods : We collected nasopharyngeal aspirates of 118 patients who were treated for respiratory symptoms at Dankook Univeristy Hospital between March 2008 and September 2009. We performed multiplex PCR for detection of Bordetella pertussis in those aspirates. Results : Of the 118 patients, 10 (8%) were positive by PCR for B. pertussis. Six episodes occurred during the period July to September 2009. Nine of the 10 patients were less than 3 months old. Seven of them had not received DTaP vaccine. The mean duration of coughing before diagnosis was 10.9${\pm}$5.2 days. Ten patients (100%) had paroxysmal cough and 8 (80%) had post-tussive vomiting. Only one patient had fever. One who had complications that include pneumonia, atelectasis and pneumomediastinum developed an absolute increase in leukocyte count (84,400/$mm^3$). There was a statistically significant relation between vaccine being received and development of complications (P =0.033). Conclusion : We suspect that there was an epidemic of pertussis between July and September 2009. Further investigation by a pediatric or nationwide surveillance system is needed to monitor the changing epidemiology for pertussis.