• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.2
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• pp.94-101
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• 1989

Transport properties of 2DEG at AlGaAs/GaAs interface such as average electron energy, flight distance, each valley occupancy ratio, average electron velocity for various fields are investigated by MONTE-CARLO method. As the electric field increases, more electrons transit drastically from (000) valley to (000) upper valley. This phenomenon shows the nonstationary effect such as velocity overshoot. The duration of the transient decreases from about 1.4 psec for electric field E = 7KV/cm to about 0.7 psec for 12KV/cm. The average electron velocity during transient transport in 2DEG is about 8 times the steady-state velocity for E = 12KV/cm at room temperature. In comparison with bulk GaAs the peak velocity in the 2DEG is higher than that in even pure bulk GaAs at electric field E = 7 KV/cm. On the basis of the fact that the electrons in the 2DEG have larger peak velocity and shorter transient time of velocity than those in the bulk GaAs, it is suggested that the device with 2DEG may obtain higher mobility than that with bulk GaAs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.880-886
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• 2007

We have proposed a new "hybrid" envelope elimination and restoration(EER) transmitter architecture using an efficiency optimized power amplifier(PA) and modified bias modulator. The efficiency of the PA at the average drain voltage is very important for the overall transmitter efficiency because the PA operates mostly at the average power region of the modulation signal. Accordingly, the efficiency of the PA has been optimized at the region. Besides, the bias modulator has been accompanied with the emitter follower for the minimization of memory effect. A saturation amplifier, class $F^{-1}$ is built using a 5-W PEP LDMOSFET for forward-link single-carrier wideband code-division multiple-access(WCDMA) at 1-GHz. For the interlock experiment, the bias modulator has been built with the efficiency of 64.16% and peak output voltage of 31.8 V. The transmitter with the proposed PA and bias modulator has been achieved an efficiency of 44.19%, an improvement of 8.11%. Besides, the output power is enhanced to 32.33 dBm due to the class F operation and the PAE is 38.28% with ACLRs of -35.9 dBc at 5-MHz offset. These results show that the proposed architecture is a very good candidate for the linear and efficient high power transmitter.

• Journal of Korean Home Economics Education Association
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• v.28 no.4
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• pp.159-167
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• 2016

This study was performed to investigate the relationship between milk consumption, dietary nutrient intake, and physical strength in Korean adolescents for dietary education of home economics subject at middle and high schools. Intake of milk and milk products, that of dietary nutrients, and physical strength records were surveyed for 298 high school students resided in small and medium-sized cities in Korea. Intake of milk and milk products was collected from three-day dietary survey, and daily dairy equivalent of calcium was calculated by dividing daily calcium intake(mg) from milk and milk products by calcium content(200 mg) of 200 mL milk. Dietary survey was performed during three days including two-weekdays and one-weekend by food record method. Dietary nutrient intake was analyzed by CAN-Pro 3.0. Physical strength records were offered from subjects' schools. Subjects were divided into low intake group(${\leq}0.29/d$), medium intake group(0.30-0.78/d) and high intake group(0.79-5.66/d) according to daily mean dairy equivalent of calcium taken by them, and most of them consumed milk and milk products less than '2' of the recommended value. Daily mean dairy equivalent of calcium was significantly related with high records of '50 m running' and 'stand long jump'(p<0.05), however it was not related with other records of physical strength. Intakes of energy, carbohydrate, protein, fat, calcium, phosphorus, iron, zinc, thiamin, riboflavin, niacin and vitamin E were significantly correlated with high record of '50 m running'(p<0.01). Intakes of nutrients were related with '50 m running' except fat were significantly correlated with high record of 'stand long jump'(p<0.05). Intakes of protein, phosphorus, iron, zinc, vitamin A, $B_6$ and E were significantly correlated with high record of 'long distance running'(p<0.05). In conclusion intake of milk and milk products was related with physical strength records('50 m running' and 'stand long jump') and intakes of most nutrients including energy nutrient, vitamin and mineral were correlated with physical strength records('50 m running', 'stand long jump' and 'long distance running') in Korean adolescents. Therefore, optimal consumption of milk and various nutrients for balanced nutrition during adolescents should be emphasized in dietary education of home economics subject for their strong physical strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.457-468
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• 2006

It is widely known that individuals with mental retardation (MR) and Down's syndrome (DS) often develop early onset periodontal diseases. In this study, the prevalence of periodontopathic bacteria in MR persons and DS patients was compared with normal persons. Plaque index and gingival index were measured. Five periodontopathic bacteria, Actinobacillus actinomycetemcomitans. Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum were surveyed in subgingival plaque samples by the polymerase chain reaction. Results : 1. Plaque index and gingival index were higher in MR persons group and DS patients group than normal persons group (p<0.05). 2. The prevalence of periodontopathic bacteria in normal persons group were lower than that of MR persons group and DS. Significant differences were observed in the prevalence of P. gingivalis, T. denticola and A. actinomycetemcomitans(P<0.05). 3. Prevalence of P. gingivalis(5.9%) at age 8-10 was lower than other ages in normal persons group, and its prevalence increased with age Prevalence of P. gingivalis, T. denticola and A. actinomycetemcomitans at MR persons group and DS patients group were higher than those of same ages of normal persons group. 4. Plaque index was associated with T. denticola and gingival index was associated with T. denticola and A. actinomycetemcomitans(P<0.05). These results suggested that plaque index, gingival index and prevalence of periodontopathic pathogens, especially P. gingivalis, T. denticola and A actinomycetemcomitans in DS patients group and MR persons group are higher than those of normal persons group.

• The Korean Journal of Air & Space Law and Policy
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• v.29 no.2
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• pp.55-86
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• 2014

The U.S. General Aviation Revitalization Act of 1994 (the "GARA") created a statute of repose that bars any claims arising from an aviation product or component more than 18 years after its date of delivery. The statute was enacted to protect general aviation aircraft manufacturers from the excessive product liability costs. The GARA included four exceptions: (a) medical emergency patients, (b) those not on the aircraft, (c) those based on written warranties, and (d) those causally related to a "knowing misrepresentation" made by the manufacturer to the FAA. The GARA also incorporates a provision for revised starting point of reckoning to which any repairs or replacements of an aviation product. This note aimed to discuss General Aviation and GARA in depth including the meaning of statue of repose, its exceptions. The various precedents about GARA were also reviewed in here as well. From the GARA, as a comparative legal issue in aviation product liability, there can be some suggestions for revision of Korean Products Liability Act. First, it seems to be reasonable to regulate the specific statute of repose provisions for various category of products. In GARA, the period of 18 years is reasonable concerning to the average aircraft life. Second, in order to avoid exhausting debate and for the judicial economy, it needs to clarify when the statute begins to run. GARA's 18 year limitation period begins to run on the different date whether it was delivered to its first purchaser or a person engaged in the business of selling the aircraft. Last but not least, proper exceptions should be added into the law for equity matter of the statute of repose does not apply. For example, a manufacturer is not protected by GARA if it knowingly misrepresents certain safety information to the FAA.

• Journal of Intelligence and Information Systems
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• v.17 no.2
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• pp.97-107
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• 2011

Nowadays there are a lot of issues about copyright infringement in the Internet world because the digital content on the network can be copied and delivered easily. Indeed the copied version has same quality with the original one. So, copyright owners and content provider want a powerful solution to protect their content. The popular one of the solutions was DRM (digital rights management) that is based on encryption technology and rights control. However, DRM-free service was launched after Steve Jobs who is CEO of Apple proposed a new music service paradigm without DRM, and the DRM is disappeared at the online music market. Even though the online music service decided to not equip the DRM solution, copyright owners and content providers are still searching a solution to protect their content. A solution to replace the DRM technology is digital audio watermarking technology which can embed copyright information into the music. In this paper, the author proposed a new audio watermarking algorithm with two approaches. First, the watermark information is generated by two dimensional barcode which has error correction code. So, the information can be recovered by itself if the errors fall into the range of the error tolerance. The other one is to use chirp sequence of CDMA (code division multiple access). These make the algorithm robust to the several malicious attacks. There are many 2D barcodes. Especially, QR code which is one of the matrix barcodes can express the information and the expression is freer than that of the other matrix barcodes. QR code has the square patterns with double at the three corners and these indicate the boundary of the symbol. This feature of the QR code is proper to express the watermark information. That is, because the QR code is 2D barcodes, nonlinear code and matrix code, it can be modulated to the spread spectrum and can be used for the watermarking algorithm. The proposed algorithm assigns the different spread spectrum sequences to the individual users respectively. In the case that the assigned code sequences are orthogonal, we can identify the watermark information of the individual user from an audio content. The algorithm used the Walsh code as an orthogonal code. The watermark information is rearranged to the 1D sequence from 2D barcode and modulated by the Walsh code. The modulated watermark information is embedded into the DCT (discrete cosine transform) domain of the original audio content. For the performance evaluation, I used 3 audio samples, "Amazing Grace", "Oh! Carol" and "Take me home country roads", The attacks for the robustness test were MP3 compression, echo attack, and sub woofer boost. The MP3 compression was performed by a tool of Cool Edit Pro 2.0. The specification of MP3 was CBR(Constant Bit Rate) 128kbps, 44,100Hz, and stereo. The echo attack had the echo with initial volume 70%, decay 75%, and delay 100msec. The sub woofer boost attack was a modification attack of low frequency part in the Fourier coefficients. The test results showed the proposed algorithm is robust to the attacks. In the MP3 attack, the strength of the watermark information is not affected, and then the watermark can be detected from all of the sample audios. In the sub woofer boost attack, the watermark was detected when the strength is 0.3. Also, in the case of echo attack, the watermark can be identified if the strength is greater and equal than 0.5.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.376-382
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• 2012

This study examined the effects of acorn (Quercus. acutissima CARR.) jelly powder (0%, 25%, 50%, and 75%) and acorn extract (0%, 0.1%, 0.5%, and 1.0%) addition on the quality characteristics of hardtack. In the sensory test, acorn jelly powder added group scored 50% higher than the other added group. Regarding hardtack color, L (lightness) and b (yellowness) values decreased with increasing acorn powder and acorn extract addition. Hardness of hardtack increased with added acorn jelly powder, but no significant difference was observed with acorn extract. The taste and texture of the hardtack 0.1% acorn extract added group significantly increased. Overall, preferences decreased with increasing acorn extract but not significantly. In conclusion, the results of this study suggest that addition of 50% acorn jelly powder in combination with addition of less than 0.1% acorn extract to hardtack was the most desirable.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.389-396
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• 2014

The physiological properties of 70% ethanol extracts from Portulaca oleracea with different extraction methods (reflux extraction, RE; autoclave extraction, AE; low temperature high pressure extraction, LTPE) were investigated. The freeze-dried powder yields of RE, AE, and LTPE were 33.78%, 30.80%, and 11.05%, respectively. The color values of L and b were higher in LTPE, and the chroma values were higher in AE and LTPE compared to RE. The total polyphenolics and proanthocyanidin contents in LTPE were significantly higher than in other extracts. The amount of substances related to flavonoids contents was highest in RE (4.30 mg/g), followed by AE (4.06 mg/g), and LTPE (4.00 mg/g). DPPH radical scavenging ability with a concentration of 500 mg% (w/v) were in the following order; LTPE (88.87%)> RE (83.84%)> AE (80.67%). Further, the reducing power, ABTS radical scavenging ability, and nitrite scavenging activity was observed in the same tendency as seen with the DPPH radical scavenging ability. However, the ferrous ion chelating activity of RE (85.45%) and AE (83.88%) was significantly higher than that of LTPE (75.60%). ${\alpha}$-Glucosidase inhibitory activities of RE and LTPE with a concentration of 100 mg% were significantly higher than AE. Xanthine oxidase, and acetylcholinesterase inhibitory activities of LTPE were higher than the other extracts. These results suggest that the extracts from Portulaca oleracea have the potential to act as functional materials, and components of Portulaca oleracea could be effective in the prevention of Alzheimer's disease, and may be used to develop various functional food products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.884-892
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• 2014

The purpose of this study was to investigate the drying characteristics and drying models of Ainsliaea acerifolia Sch. Bip. using far-infrared thin layer drying. Far-infrared thin layer drying test on Ainsliaea acerifolia Sch. Bip. was conducted at two air velocities of 0.6 and 0.8 m/sec, as well as three drying temperatures of 40, 45, and $50^{\circ}C$ respectively. The drying models were estimated using coefficient of determination and root mean square error. Drying characteristics were analyzed based on factors such as drying rate, leaf color changes, antioxidant activity, and contents of polyphenolics and flavonoids. The results revealed that increases in drying temperature and air velocity caused a reduction in drying time. The Thompson model was considered suitable for thin layer drying using far-infrared radiation for Ainsliaea accerifolia Sch. Bip. Greenness and yellowness values decreased and lightness values increased after far-infrared thin layer drying, and the color difference (${\Delta}E$) values at $40^{\circ}C$ were higher than those at $45^{\circ}C$ and $50^{\circ}C$. The antioxidant properties of Ainsliaea acerifolia Sch. Bip. decreased under all far-infrared thin layer drying conditions, and the highest polyphenolic content (37.9 mg/g), flavonoid content (22.7 mg/g), DPPH radical scavenging activity (32.5), and ABTS radical scavenging activity (31.1) were observed at a drying temperature of $40^{\circ}C$ with an air velocity of 0.8 m/sec.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.12
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• pp.2008-2020
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• 2020

Objective: This study was conducted to investigate the effects of dietary corn resistant starch (RS) on the intestinal morphology and barrier functions of broilers. Methods: A total of 320 one-day-old broilers were randomly allocated to 5 dietary treatments: one normal corn-soybean (NC) diet, one corn-soybean-based diet supplementation with 20% corn starch (CS), and 3 corn-soybean-based diets supplementation with 4%, 8%, and 12% corn resistant starch (RS) (identified as 4% RS, 8% RS, and 12% RS, respectively). Each group had eight replicates with eight broilers per replicate. After 21 days feeding, one bird with a body weight (BW) close to the average BW of their replicate was selected and slaughtered. The samples of duodenum, jejunum, ileum, caecum digesta, and blood were collected. Results: Birds fed 4% RS, 8% RS and 12% RS diets showed lower feed intake, BW gain, jejunal villus height (VH), duodenal crypt depth (CD), jejunal VH/CD ratio, duodenal goblet cell density as well as mucin1 mRNA expressions compared to the NC group, but showed higher concentrations of cecal acetic acid and butyric acid, percentage of jejunal proliferating cell nuclear antigen-positive cells and delta like canonical Notch ligand 4 (Dll4), and hes family bHLH transcription factor 1 mRNA expressions. However, there were no differences on the plasma diamine oxidase activity and D-lactic acid concentration among all groups. Conclusion: These findings suggested that RS could suppress intestinal morphology and barrier functions by activating Notch pathway and inhibiting the development of goblet cells, resulting in decreased mucins and tight junction mRNA expression.