• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.599-602
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• 2005

In this paper, we have performed a study that modifies the CPW Pad configurations to improve an $f_{max}$ characteristic of metamorphic HEMT. To analyze the CPW Pad structures of MHEMT, we use the ADS momentum simulator developed by $Agilent^{TM}$. Comparing the employed structure (G/W = 40/100 m), the optimized structure (G/W = 20/25 m) of CPW MHEMT shows the increased $S_{21}$ by 2.5 dB, which is one of the dominant parameters influencing the $f_{max}$ of MHEMT. To compare the performances of optimized MHEMT with the employed MHEMT, DC and RF characteristics of the fabricated MHEMT were measured. In the case of optimized CPW MHEMT, the measured saturated drain current density and transconductance $(g_m)$ were 693 mA/mm and 647 mS/mm, respectively. RF measurements were performed in a frequency range of $0.1{\sim}110$ GHz. A high $S_{21}$ gain of 5.5 dB is shown at a millimeter-wave frequency of 110 GHz. Two kinds of RF gains, $h_{21}$ and maximum available gain (MAG), versus the frequency, and a cut-off frequency ($f_t$) of ${\sim}154$ GHz and a maximum frequency of oscillation ($f_{max}$) of ${\sim}358$ GHz are obtained, respectively, from the extrapolation of the RF gains for a device biased at a peak transconductance. An optimized CPW MHEMT structure is one of the first reports among fabricated 0.1 m gate length MHEMTs.

• Imaging Science in Dentistry
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• v.47 no.2
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• pp.123-127
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• 2017

Purpose: Obstructive and inflammatory disease often occurs in the major salivary glands, and no predictive treatment has yet been developed for this condition. The aim of this report was to introduce an intraductal irrigation procedure and to illustrate its application to practical patient cases. Materials and Methods: Two patients complaining of pain and swelling in the parotid gland during meals who underwent sialography were diagnosed as having sialodochitis with sialadenitis. Intraductal irrigation was then performed on the parotid gland on the side of the complaint. The irrigation procedure was conducted in the same manner as the sialography procedure, except that saline was used as the filling solution. Symptom severity was evaluated with a numerical rating scale (NRS) at the initial visit and a month after the irrigation. Results: The initial NRS value of patient 1 was 10. The value decreased to 6 and then to 0 after 2 irrigation procedures. The NRS value of patient 2 regarding the symptoms involving the left parotid gland decreased from 4-5 to 1 after 4 irrigation procedures performed at 1-month intervals. Conclusion: Intraductal irrigation of the salivary gland may be a simple, safe, and effective treatment option for patients with obstructive and inflammatory disease of the salivary gland that is capable of resolving their symptoms.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.2
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• pp.99-105
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• 2018

This study was carried out to estimate the effect of selected inoculants on chemical compositions and fermentation characteristics of rye silage. Rye was harvested at dough stage and divided into 5 treatments, following: No additives (CON); L. plantarum R48-27 (LP27); L. buchneri R4-26 (LB26); Mixture of LP27 and LB26 at 1:1 ratio (MIX); and L. buchneri (LB). The rye forage was ensiled into 10 L bucket silo for 100 days. The contents of NDF and ADF were lowest (P<0.05) in LB26. The pH in LB26, MIX, and LB were lower (P<0.05) than CON and LP27. Lactate content in LB was higher (P<0.05) than the others, while acetate content in LB26 and LB were higher (P<0.05) than that in CON and LP27. Lactate to acetate ratio was highest (P<0.05) in LB, but lowest in LB26. Lactic acid bacteria (LAB) count in LB was higher (P<0.05) than that in CON, while yeast count in CON was lower than in all silages applied inoculants. In conclusion, silages inoculated with LB26 could improve potentially the aerobic stability caused by increases of acetate and propionate concentrations.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.51-59
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• 2004

Phylogenetic relationships were analyzed among bumblebees using a portion of mitochondrial (mt) 16S ribosomal RNA (16S rRNA). Eight species of true bumblebees and one species of cuckoo bumblebee (Bombini, Apidae), collected from Korea were included in the analysis. Also, one species of true bumblebee imported from several foreign countries for pollination was included. The length of mt 16S rRNA sequence ranged from 496 bp to 508 bp and sequence divergence ranged from 1.4％ (7 bp) to 15.49％ (77bp). As expected, a high A＋T content was observed (78.5％ on average). According to the phylogeny tree derived from parsimony and maximum likelihood analysis, a monphyletic Bombus species, excluding a single cuckoo bumblebee, Psithyrus coreanus, was obtained, but the bootstrap estimate at the node supporting the monophyletic group was very weak (40％ or 46％), suggesting a very close relationship of the cuckoo bumblebee to the true bumblebee. Within Bombus species belonging to identical subgenera subgeneric specific clustering was formed with high bootstrap values, implying validity of the subgeneric names of each species: Pyrobombus for B. ardens and B. modeatus; Megabombus for B. consobrinus wittenburgi and B. koreanus; and Bombus s. str. for B. ignitus, B. hypocrita sapporoensis, and B. terrestris.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.709-719
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• 2005

The forward link of the 3 G CDMA system may become limited under the increasing of the number of users. The conventional channelization code, Walsh code, has not enough sizes for much possible non, therefore, the quasi orthogonal function(QOF), which process optimal cross-correlation with Walsh code, is considered. In this paper, we investigate quasi orthogonal function on Jacket matrices, which can lead lower correlations values and better performance in 3 G CDMA system. Moreover, to simple the detector and improve the BER performance, a novel detection for QOF CDMA system is proposed. Finally, the simple recursive generation of the bent sequences for QOF mask function is discussed.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.203-210
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• 2007

The delivery load data obtained from Nakdong river basin are used for developing the model estimating the daily delivery load on the main side streams of Nakdong River. The developed model assesses the daily contamination loads of the main thirteen side streams that contribute to the main stream of Nakdong river. It is developed that the model using the simplified equation that can estimate the daily delivery loads on the side main streams of Nakdong river for a period of having no data of the water quality and flow. The developed model for estimating the daily delivery loads from the main side streams in Nakdong river basin on each item such as BOD, TN, and TP is expressed as Daily delivery load ($\frac{kg}{day}$) = Production load $(\frac{kg}{day}){\times}(1-{\alpha}){\times}(\frac{daily\;runoff}{average\;runoff\;per\;year}){\gamma}$. The estimated values obtained by using the model are almost fit to the calculated values (real data) that have been acquired from the thirteen main side streams in Nakdong river basin. The correlation coefficient values, R, that indicate the correlation between the estimated and the calculated show over 0.7 that mean the estimated values from the used model are adapted to the real data except TN values of Nam-river, Hwang-river, Gam-river, We-river. Especially, the correlation of TP values between the estimated and the calculated implies quite a creditable data to use.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.485-493
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• 1999

This paper presents the results of the first interlaboratory comparison of ambient particles measurement conducted by 5 laboratories under the framework of Korean Society for Atmospheric Environment(KOSAE) on the May of 1998 in Seoul. Collection of particles less than 10$mu extrm{m}$(PM10) was carried out by two different types of PM10 sampler, and their concentration reported by three laboratories ranged from 36.2~56.05$\mu\textrm{g}$/㎥. Analyses of chemical composition of particles collected by each lab were performed by the destructive and nondestructive instrumental methods. Statistical analysis of the measurement results could not be carried out because a comprehensive QA/QC had not been applied before experiment. The importance of QA/QC as well as the performance of QA/QC for the measurement of PM10 was discussed in detail.

• Journal of Korea Association of Health Promotion
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• v.4 no.1
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• pp.85-94
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• 2006

Background Cardiovascular disease is becoming an important national health issue since its recent increase in incidence and mortality. The study was conducted to find out the prevalence of metabolic syndrome according to the clinical identification criteria by NCEP-ATP3 and Asia-Pacific criteria. Meterials & Methods: The subjects were 759 people -male 375 and female 384 after twenties age - who had undergone medical examinations at Korea Association of Health, Daejeon- Chungnam Branch. The prevalence of metabolic syndrome was assessed as defined by the NCEP ATP3, while abdominal obesity was assessed according to the Asia-Pacific guidelines. Anthropometric variables and cardiovascular risk factors were measured, and Associated factors with metabolic syndroms was analyzed by logistic regression analysis. Results The prevalence of metabotic syndrome was 24.O% for male and 27.1% for female The high blood pressure was the highest prevalent risk factors of metabolic syndrome. In the age group of thirties, the prevalence of metabolic syndrome was higher in men than in women, however it was significantly higher in women than in men in fifties and six ties. The metabolic syndrome was more prevalent in aged people over 50 years. and .significantly associated with BMI index(odds ratio 2.58 in male, 9.87 in female)Conclusions The prevalence of metabolic syndrome is over 20%.Early detection and intervention of risk factors by health examination and promotion are needed for prevention of metabolic syndrome.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.75-84
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• 2018

This study investigated the pollution status of polycyclic aromatic hydrocarbons (PAHs) such as benzopyran, which is a harmful substance, in convergence herbal pills distributed in Seoul. During 2010 ~ 2013, 31 items and 93 samples were collected from the herbal medicines vendors in Seoul, and the samples were extracted, filtered, concentrated, and then spun out with SPE (Sep-pak florisil) and concentrated again and analyzed by liquid chromatography. The results of the analysis showed that the average contents of PAHs were below $10{\mu}g/kg$, and the PAHs were lower than those of daily life exposure, and MOEs was evaluated as safe to a negligible level. In the future, comparative fusion studies on the harmful substances of medicinal pills and food pills are needed.

• Journal of the Korean Ceramic Society
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• v.43 no.7 s.290
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• pp.393-401
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• 2006

The development of Korean glaze originated from the development of ash glazes. Ash not only has strong solubility but also can shows the glaze a variety of different colors according to what the glaze has in it as the main component. In addition, it gives a feeling of lucidness and softness. For these reasons, there are a lot of needs for ash and many potters want to take advantage of ashes as glaze. But natural ashes have not been widely used as glaze primarily because it is relatively hard to find or manufacture. Considering the difficulty of finding or manufacturing natural ashes, this study aims to formulate synthetic ash which not only is available to the potters in general but also has the sam ε characteristics as the natural ashes. To achieve this aim, this study examines the characteristics of the pine tree ash, the main component of the glaze of celadon porcelains, and the red pepper stem ash, the main component of the brown glaze, both of which have been used by the Korean traditional potters. In this study, the alkaline component of the glaze. A important ingredient when the ashes are synthesized, was supplied by mixing of $Na_2CO_3$, Chungju limestone and rice straw ash. Furthermore, the synthetic ash, when it shows no change of pH in its composition rate of 6:2:2, was found to be usable as the most stable material. In conclusion, the formula which frits some raw $materials-Na_2CO_3$, Chungju limestone and rice straw ash-can duplicate the synthetic ash which is simila to the natural ash.