• Journal of IKEEE
• /
• v.14 no.1
• /
• pp.65-74
• /
• 2010

The Digital TV(DTV) standard has ushered in a new era in TV broadcasting and raised a great demand for DTV tuners. There are many challenges in designing a DTV tuner, of which the most difficult part is the frequency synthesizer. This paper presents the design of a frequency synthesizer for DTV Tuners in a $0.18{\mu}m$ CMOS process. It satisfies the DTV(ATSC) frequency band(54~806MHz). A scheme is proposed to cover the full band using only one VCO. The VCO has been designed to operate at 1.6~3.6GHz band such that the LO pulling effect is minimized, and reliable broadband characteristics have been achieved by reducing the variations of VCO gain and frequency step. The simulation results show that the designed VCO has gains of 59~94MHz(${\pm}$17.7MHz/V,${\pm}$23%) and frequency steps of 26~42.5MHz(${\pm}$8.25MHz/V,${\pm}$24%), and a very wide tuning range of 76.9%. The designed frequency synthesizer has a phase noise of -106dBc/Hz at 100kHz offset, and the lock time is less than $10{\mu}$sec. It consumes 20~23mA from a 1.8V supply, and the chip size including PADs is 2.0mm${\times}$1.8mm.

• Journal of Korean Society of Forest Science
• /
• v.106 no.2
• /
• pp.111-120
• /
• 2017

The best source of information on the conservation status of species at a global scale is the IUCN Red List of Threatened Species. Until now, 236 vascular plants from Korean peninsula have been evaluated using the IUCN red list categories and criteria. It indicated that five taxa were considered as critically endangered, 20 as endangered and nine as vulnerable species as a threatened status. On the other hand, the rest (189 taxa) were assessed as a least concern, which did not qualify for threatened species categories. Korea Ministry of Environment published a revised version of 57 species list by re-classifying endangered species with idiosyncratic qualitative criteria for two levels (I and II) followed by status reviews in 2011. However, two thirds species proposed by Ministry of Environment do not qualify as threatened. The major difficulties found in applying IUCN Red List criteria at the global scale was a lack of knowledge on the status of species at broader geographic scales and the perceived difficulty the causes. The lack of consistency between two lists constrains the prioritization of species-based conservation work at the national level. Due to a lack of centralized monitoring data for most species, this status is largely qualitatively and so it carries a high level of uncertainty. This is reflected in the high number of species with an unknown population trend. The current list of endangered species of flora and fauna by the Ministry of Environment should be recognized as the national list (local and population extinction), which is different from the IUCN Red list due to the different geographical contexts. Also, it is necessary to improve the quality of evaluation and conservation management system rather than presenting massive number of endangered species list.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.10
• /
• pp.1543-1549
• /
• 2015

Black rice bran, a by-product from rice milling process, is a good natural source of anthocyanin pigment. The purpose of this study was to determine the optimum conditions for anthocyanin extraction from black rice bran as well as the stability of anthocyanin extract according to different storage temperatures. The main anthocyanin in 'Heugkwang' rice bran was identified as cyanidine-3-glucoside (C3G) by HPLC and LC-MS/MS. The yield and C3G content of black rice bran extract were investigated with various extraction solvents, temperatures, and times. The results indicate that the optimum extraction solvent, temperature, and time were 50% ethanol, $70^{\circ}C$, and 2 h, respectively. The stability of anthocyanin extract was studied during a storage period of 168 days at various temperatures ($-20^{\circ}C$, $4^{\circ}C$, and room temperature). Hunter's values (L, a, and b) of anthocyanin extract increased, whereas C3G content continuously decreased up to 168 days. Variations in Hunter's values and C3G content become larger as storage temperature increased. Anthocyanin extract from black rice bran was very stable, as C3G content after storage at all temperatures was maintained at more than 90% of initial content. These results suggest that anthocyanin extract from black rice bran may be useful as a natural food colorant.

• Journal of Pharmaceutical Investigation
• /
• v.31 no.1
• /
• pp.49-55
• /
• 2001

Acetyl-L-carnitine (ALC), an endogenous component of the L-carnitine family, is naturally occurring molecule synthesized from L-carnitine (LC) by carnitine acetyl transferase. ALC has been shown to improve the cognitive performance of patients suffering from dementia of the Alzheimer's type and proposed for treating Alzheimer's disease in pharmacological doses. The purpose of the present study was to evaluate the bioequivalence of two ALC tablets, $Nicetile^{TM}$ (Dong-A pharmaceutical Co., Ltd.) and $Neurocetil^{TM}$ (Kyung-Dong Pharmaceutical Co., Ltd.), according to the guidelines of Korea Food and Drug Administration. Twenty six normal male volunteers, $22.80{\pm}2.76$ year in age and $63.07{\pm}7.98\;kg$ in body weight, were divided into two groups and a randomized $2{\times}2$ cross-over study was employed. After one tablet containing 500 mg of ALC was orally administered, blood was taken at predetermined time intervals and the concentrations of ALC in serum were determined using HPLC with fluorescence detector. Because of the presence of endogenous ALC, the calibration was performed using dialyzed serum. Pharmacokinetic parameters such as $AUC_t$, $C_{max}\;and\;T_{max}$ were calculated and ANOVA was utilized for the statistical analysis of the parameters. The results showed that the differences in $AUC_t$, $C_{max}\;and\;T_{max}$ between two tablets were 2.72%, -0.65% and -8.42%, respectively, when calculated against the $Nicetile^{TM}$ tablet. The powers $(1-{\beta})$ for $AUC_t\;and\;C_{max}$ were 94.87% and 87.17%, respectively. Minimum detectable differences $({\Delta})$ at ${\alpha}=0.05$ and $1-{\beta}=0.8$ were less than 20% (e.g., 15.58% and 19.16% $AUC_t\;C_{max}$, respectively). The 90% confidence intervals were within ${\pm}20%$ (e.g., $-11.84{\sim}6.41$ and $-10.57{\sim}11.88$for $AUC_t\;and\;C_{max}$, respectively). Two parameters met the criteria of KFDA for bioequivalence, indicating that $Neurocetil^{TM}$ tablet is bioequivalent to $Nicetile^{TM}$ tablet.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.12
• /
• pp.1858-1864
• /
• 2014

In the present investigation, the anti-diabetic potential of 80% ethanol extract of Eleutherococcus senticosus leaves (EEES) was examined based on ${\alpha}$-glucosidase inhibitory activities. EEES was sequentially fractionated with n-hexane, chloroform, ethyl acetate (EtAOc), n-butanol, and $H_2O$. Of the various fractions, EtAOc fraction effectively inhibited ${\alpha}$-glucosidase activity by 68.05%. Therefore, EtAOc fraction was selected for further isolation and identification studies. EtAOc fraction was separated by medium pressure liquid chromatography with silica and ODS gel to yield eight fractions (EAA~EAH). Based on the results of ${\alpha}$-glucosidase inhibitory activity, EAH fraction was re-chromatographed to yielded four more fractions (EAHA~EAHD). Of these, EAHC fraction showed higher ${\alpha}$-glucosidase inhibitory activity of 93.60%. EAHC fraction was re-chromatographed and yielded EAHCA and EAHCB fractions. Further, identification and chemical structures of these two fractions were analyzed using $^1H$-NMR, $^{13}C$-NMR, and mass spectra data. Based on the results of the spectral data, the isolated compounds were identified as hyperoside and isoquercetin. Results of the present study indicate that the isolated compounds, hyperoside, and isoquercetin from leaves of E. senticosus could be used for the development of new anti-diabetic drugs.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.25 no.5
• /
• pp.846-854
• /
• 1996

High dietary fiber(DF) diets lower blood glucose and insulin requirements in diabetics. In this study we evaluated the effects of high dietary fiber(DF) food supplements on glucose metabolism in thirty-four subjects with non-insulin-dependent diabetes mellitus(NIDDM). The subjects were divided into three test groups. Each group's prescribed hospital diets were augmented by one of the three following DF supplements for two weeks: Soybean biscuits containing 5g of total DF-the control group(n=15); Biji biscuits containing 20g of total DF-the high insoluble DF group(n=9); and sea tangle biscuits containing 25g of total DF-the high soluble DF group(n=10). The mean daily DF intake of the subjects during the period were: $19.1\pm4.3g$ for the soybean control group; $32.5\pm4.1g$ for the Bijl group; and $38.1\pm5.5g$ for the sea tangle group. The supplementation of the Biji or sea tangle biscuits singnificantly lowered fasting serum glucose levels(p < 0.05) and resulted in the improvement of glucose tolerance. However, the secretions of insulin, C-peptide, and glucagon and Hb $A_{lc}$ concentration were not affected by the high fiber supplementary feeding for two weeks. The urinary excretion of glucose decreased remarkably after the addition of the DF supplements in all three groups(p<0.05). The results indicate that the supplementation of Biji or sea tangle bascuits possesses a beneficial effect on the improvement of glucose metabolism in subjects with NIDDM.

• Journal of Ginseng Research
• /
• v.42 no.3
• /
• pp.270-276
• /
• 2018

Background: Notoginsenoside Ft1 is a promising potential candidate for cardiovascular and cancer disease therapy owing to its positive pharmacological activities. However, the yield of Ft1 is ultralow utilizing reported methods. Herein, an acid hydrolyzing strategy was implemented in the acquirement of rare notoginsenoside Ft1. Methods: Chemical profiles were identified by ultraperformance liquid chromatography coupled with quadruple-time-of-flight and electrospray ionization mass spectrometry (UPLC-Q/TOF-ESI-MS). The acid hydrolyzing dynamic changes of chemical compositions and the possible transformation pathways of saponins were monitored by ultrahigh-performance LC coupled with tandem MS (UHPLC-MS/ MS). Results and conclusion: Notoginsenoside Ft1 was epimerized from notoginsenoside ST4, which was generated through cleaving the carbohydrate side chains at C-20 of notoginsenosides Fa and Fc, and vinaginsenoside R7, and further converted to other compounds via hydroxylation at C-25 or hydrolysis of the carbohydrate side chains at C-3 under the acid conditions. High temperature contributed to the hydroxylation reaction at C-25 and 25% acetic acid concentration was conducive to the preparation of notoginsenoside Ft1. C-20 epimers of notoginsenoside Ft1 and ST4 were successfully separated utilizing solvent method of acetic acid solution. The theoretical preparation yield rate of notoginsenoside Ft1 was about 1.8%, which would be beneficial to further study on its bioactivities and clinical application.

• Journal of agriculture & life science
• /
• v.45 no.6
• /
• pp.151-162
• /
• 2011

Methanol and hexane extracts from 35 species in 27 families of herbal plants were evaluated for their acaricidal activities against two-spotted spider mite, Tetranychus urticae by leaf-dipping and spraying methods in laboratory, pot and field, respectively. Acaricidal activities were different depending on herbal plants. When T. urticae was released on leaves of Phaseolus vulgaris var. humilis that were dipped in the 1,000 ppm hexane extracts from fruits of Torreya nucifer and Daphan genkwa, seeds of Xanthium strumarium and Pharbitis nil at one minute they experienced 56.8, 47.8, 47.7, and 47.7% mortalities, respectively. Dipping time influenced acaricidal activity, that is, one minute dipping was more effective than 30 second dipping of Phaseolus vulgaris var. humilis leaves. However, extracts of X. strumarium and P. nil seeds had comparatively high activities. Concentration of hexane extract of X. strumarium and P. nil seeds revealing LC50 were 1,824 and 1,899 ppm, respectively. Extracts of both plants from hot and cold water were not effective representing <20% mortality at 1,000 ppm. However, hexane extracts of X. strumarium and P. nil seeds were effective against T. urticae on P. vulgaris var. humilis representing 76.3 and 71.3% mortalities in pot, respectively. Control effects of hexane extract of P. nil seed were 50.8 and 35.1% at 2,000 and 1,000 ppm against T. urticae on Chrysanthemum morifolium in greenhouse, respectively.

• Applied Chemistry for Engineering
• /
• v.30 no.2
• /
• pp.205-211
• /
• 2019

Over the past several decades, the polymer dispersed liquid crystal (PDLC) has received particular attention as a material for developing smart window due to their electro-optical switchable properties. In this study, PDLC cells were fabricated using acrylate monomers, namely 2-hydroxyethyl acrylate (2-HEA) and ethylene glycol phenyl ether acrylate (EGPA), and the effect of the monomer composition on their electro-optical properties was investigated. The monomer mixture with a low viscosity (~10 cps) was easily filled between indium tin oxide (ITO) glasses by capillary action at room temperature. PDLC cells prepared using the mixture ratio of 1 : 9 (2-HEA : EGPA) did not show a complete opaque state at a 0 V condition but exhibited unstable electro-optical properties under an electric field. As the LC composition increased in the reaction mixture for PDLC cell preparation, the $V_{th}$ (threshold voltage) and $V_{sat}$ (saturation voltage) values as well as contrast ratio (CR) increased. $V_{th}$ and $V_{sat}$ values also increased with the cell gap thickness. PDLC cells with a $20{\mu}m$ cell gap thickness exhibited higher CR than those with 10 and $40{\mu}m$ cell gap thicknesses. Particularly, PDLC cells prepared using the mixture ratio of 7 : 3 (2-HEA : EGPA) showed excellent electro-optical properties such as a low driving voltage and high contrast ratio.

• Korean Journal of Remote Sensing
• /
• v.36 no.6_1
• /
• pp.1277-1290
• /
• 2020

Water resources which is formed of surface and groundwater, are considered as one of the pivotal natural resources worldwide. Since last century, the rapid population growth as well as accelerated industrialization and explosive urbanization lead to boost demand for groundwater for domestic, industrial and agricultural use. In fact, better management of groundwater can play crucial role in sustainable development; therefore, determining accurate location of groundwater based groundwater potential mapping is indispensable. In recent years, integration of machine learning techniques, Geographical Information System (GIS) and Remote Sensing (RS) are popular and effective methods employed for groundwater potential mapping. For determining the status of the integrated approach, a systematic review of 94 directly relevant papers were carried out over the six previous years (2015-2020). According to the literature review, the number of studies published annually increased rapidly over time. The total study area spanned 15 countries, and 85.1% of studies focused on Iran, India, China, South Korea, and Iraq. 20 variables were found to be frequently involved in groundwater potential investigations, of which 9 factors are almost always present namely slope, lithology (geology), land use/land cover (LU/LC), drainage/river density, altitude (elevation), topographic wetness index (TWI), distance from river, rainfall, and aspect. The data integration was carried random forest, support vector machine and boost regression tree among the machine learning techniques. Our study shows that for optimal results, groundwater mapping must be used as a tool to complement field work, rather than a low-cost substitute. Consequently, more study should be conducted to enhance the generalization and precision of groundwater potential map.