• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.638-640
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• 2000

The main source of vibration in SRM drive is generated by rapid change of radial force when phase current is extinguished by commutation action. In this paper a hybrid excitation method is proposed to reduce vibration and acoustic noise of SRM. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are reduced because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.

• Journal of Environmental Science International
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• v.17 no.10
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• pp.1121-1127
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• 2008

The free-living amoeba and Acanthamoeba sp. are widely distributed in fresh water, soil, air and dust in the world. We studied distribution of amoeba from low Nakdong River(Mulgum and Maeri) and removal efficiency in water treatment process of Busan metropolitan city. During this investigation, water quality showed pH $7.4{\sim}9.6({\pm}1.1)$, water temperature $2.0{\sim}29.0({\pm}17)^{\circ}C$, turbidity $4.8{\sim}27.4({\pm}11.0)$ NTU, chlorophyll-a $10.3{\sim}109.0({\pm}44.3)\;mg/m^{3}$, BOD $1.7\sim4.9({\pm}2.6)$ mg/L, COD $3.1\sim-6.9({\pm}5.0)$ mg/L and total coliform $17\sim920({\pm}200.5)$ MPN/100 mL. The free-living amoeba were detected highly than Acanthamoeba sp., 11 out of 22 in raw water samples were positive (50%) for Acanthamoeba sp. from February 2005 to December 2005. The seasonal characteristics of tree-living amoeba and Acanthamoeba sp. in raw water were mainly distributed through the spring to the early fall. When tree-living amoeba and Acanthamoeba sp. were passed through the water treatment of pilot-plant, approximately 80% was sure to be removed through pre-ozonation, sedimentation, send filtration. 100% was removed after post-ozonation process. All of the isolated amoebas from Nakdong River were Acanthamoeba sp. AC311 18S ribosomal RNA gene with 98% nucleotide sequence homology.

• The Korean Journal of Ecology
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• v.15 no.3
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• pp.311-328
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• 1992

In other to classify calcicoles and calcifuges and calcifuges within plant communities occurring on limestone and granite soils in chungbuk province, korea, soil propertile, constancy for species by prsence or absence, and ratios of soluble to insoluble $Ca^{2+}$ and $Mg^{2+}$ were investigated. In the limestone soils ph values and $Ca^{2+}$ and $Mg^{2+}$ content, ranging 7.26 ~7.48, 5.32~7.37 mg $Ca^{2+}/g$ and 0.42~0.62 mg $Mg^{2+}/g$, respectively, were higher than those in the granite soil with ph 5.76, 1.03mg $Ca^{2+}/g$ and 0.24mg $Mg^{2+}/g$. species with high constancy in the 5 communities were classified into three groups; species group a(29~36% of total number of species) was composed of species occuring on the granite soil; group c(16~24%) is commonly distributed throughout both soils. Ratios of soluble to insoluble $Ca^{2+}$ and $Mg^{2+}$ ranged from 0.1 to 81.3 in the group a, 0.2 to 0.8 in the group b and 0.2 to 8.7 in the group c. species within each group can be divided into two groups based on the values of the ratio, below or above 1.0. consequently, each of the group a and c was classified again into two groups; the group a1 and c1 with the ratio of above 1.0 and the group a2 and c2 withbelow 1.0 but the ratio could not further subdivide the group b. from these results it was proposed that plants of the group a1 were termed as obligate calcicoles, the group b as obligate calcifuges, the group c1 as facultative calcicoles, the group c2 as facultative calcifuges and the group a2 as avoiding calcifuges.

• Korean Journal of Materials Research
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• v.15 no.1
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• pp.25-30
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• 2005

The microstructural changes by hot extrusion of AZ31B magnesium alloy were observed, and the relation to the tensile property was examined. The tensile properties as oriented longitudinal(L), half transverse(HT) and long transverse(LT) to the extrusion direction were investigated at $20^{\circ}C,\;100^{\circ}C,\;200^{\circ}C,\;300^{\circ}C\;and\;400^{\circ}C$, respectively. As the results, many recrystallized small grains distributed uniformly in large banded microstructures formed along the extrusion direction. The grain size of as-extruded specimen was around $30\~150\;{\mu}m$. As increasing the test temperature the tensile and yield strength with respect to the angle between the axis of the tensile and the longitudinal direction in extrusion was decreased, but their elongation were increased and their deviation between L and LT specimens have disappeared from $300^{\circ}C$. This mechanical anisotropy was reduced at elevated temperatures and almost disappeared at $400^{\circ}C$. It was considered that the homogenization was occured by the recrystallization and the change of slip system was occurred during tensile test process in elevated temperatures.

• Journal of Preventive Medicine and Public Health
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• v.28 no.4 s.51
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• pp.863-873
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• 1995

This report describes a preperation and characterization of canine blood lead(Pb) standard reference material(SRM). Three adult beagle dogs(A, B, and C)were orally dosed with gelatin capsules containing $Pb(NO_3)_2$, equivalent to $10\sim80mg$ Pb/kg body weight. Blood was drawn 24 hours after the dose from the cephalic vein into lead free 500ml Pyrex beaker in which EDTA.K was contained as an anticoagulant. The amount of lead given to individual dog was varied arbitrarily. Three month later, 3 canine animals were orally dosed with lead secondarily to make mixed SRM(D1) which was mixed different concentrations of lead in bloods with A1, B1, and C1 in vitro. The SRMs for A, B, C, A1, B1, C1, and D1 were distributed 2ml each into more than 300 lead free bottles, and were stored in refregerator at $4^{\circ}C$. The amount of lead in canine whole blood samples were determined using a Varian 30A atomic absorption spectrophotometer(AAS) with a model GTA-96 graphite tube atomizer with D2 background correction and a Hitachi Z-8100 AAS with Zeeman background correction. The sensitivity and detection limits for lead determination of Varian 30A were $0.46{\mu}g/L,\;0.34{\mu}g/L,\;and\;0.56{\mu}g/L,\;0.14{\mu}g/L$ of Hitachi Z-8100, respectively. Day to day variations in determination of blood lead concentration in a certain sample were $31.11{\pm}1.36{\mu}g/100ml$ by Varian 30A, and $33.08{\pm}0.82{\mu}g/100ml$ by Hitachi Z-8100, showing the difference of 3% between the two results. At the blood lead concentrations of $56.31{\pm}1.98{\mu}g/100ml(A),\;40.89{\pm}0.80{\mu}g/100ml(B),\;59.01{\pm}1.38{\mu}g/100ml(C)$, the precisions of replicated measurements by AAS were 3.52%, 1.96%, and 2.34%, respectively. Coefficient variation(CV) of SRMs(A, B, and C) within a standard sample were ranged from 0.92% to 7.50%, and those between 5 standard samples were 1.21%, 2.64%, and 1.11%, respectively, showing inter-vial variation of $1{\mu}g/100ml$. Lead levels in SRMs during one month storage were unchanged. The overall recoveries were $89.6\sim100.4%,\;91.6\sim101.9%,\;90.3\sim100.0%$ for A, B, and C SRMs, means were $56.46{\pm}2.69{\mu}g/100ml,\;39.35{\pm}1.89{\mu}g/100ml,\;57.40{\pm}2.31{\mu}g/100ml$, and measurement ranges were$52.88{\pm}59.26{\mu}g/100ml,\;37.47{\pm}41.68{\mu}g/100ml,\;54.80{\pm}60.69{\mu}g/100ml$, respectively. Those results were laid within confidence limits values. The lead concentrations in the mixed sample(D1) stored over one month period were ranged from $32.76{\mu}g/100ml\;to\;33.54{\mu}g/100ml$, with CV ranging from 1.2% to 2.7%. The results were similiar to each of single samples(A1, B1, and C1) in respect of homogeneity and stability. Results of the mixed blood sample analysed after 1 month storage at $4^{\circ}C$ by four other laboratories(L1, L2, L3, L4) were similar with those of our laboratory($L5;31.18{\pm}0.24{\mu}g/100ml$, acceptable range by $CDC;25.18\sim37.18{\mu}g/100ml$), showing the concentrations of $25.91{\pm}1.19{\mu}g/100ml(L1),\;34.16{\pm}0.22{\mu}g/100ml(L2),\;35.68{\pm}0.85{\mu}g/100ml(L3),\;30.95{\pm}0.46{\mu}g/100ml(L4)$ in a each samples.

• Food Engineering Progress
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• v.21 no.3
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• pp.249-255
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• 2017

Caesalpinia sappan L. is an oriental medicinal plant distributed in the Asia Pacific region including India, Malaysia, and China. The dried heartwood of Caesalpinia sappan has been traditionally used as an analgesic and anti-inflammatory drug. In this study, the effects of extract methods of C. sappan on contents of total polyphenols and flavonoids, antioxidant activity, and cytotoxic activity were evaluated. As a result, hot water extract from C. sappan (CSWE) significantly exhibited contents of total polyphenols and flavonoids (22.6 mg GAE/g and 14.5 mg QE/g) higher than 70% ethanol extract (CSEE) (17.6 mg GAE/g and 13.2 mg QE/g). However, CSEE showed greater antioxidant activity than CSWE in both DPPH and ABTS. Also, the cytotoxicity of C. sappan against three kinds of cancer cell lines was higher in CSEE than in CSWE. These results show that ethanol extract is a better extract method than hot water method to maintain antioxidant and anti-cancer activities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1617-1624
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• 2006

This paper presents system modeling, modified space vector PWM implementation and design of a closed loop controller of the Z-source inverter which consists of L and C components and shoot-through zero vectors for DGS. Zero vector periods of SVPWM utilized to boost DC-link voltage instead of conventional DC/DC converter and transformer. Only two shoot-through vut(nn are used for DC link voltage control during one switching period without loss of non-zero vectors. Discrete time sliding mode controller, robust servomechanism controller are designed to realize fast and no-overshoot current response and a steady state voltage error. Simulation results are shows the effectiveness of the proposed algorithm.

• Journal of Marine Bioscience and Biotechnology
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• v.10 no.1
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• pp.18-25
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• 2018

Chlorella is quantitatively and qualitatively high in protein with balanced essential amino acid profiles, vitamins and minerals. ${\gamma}-Aminobutyric$ acid (GABA) is broadly distributed in nature and fulfills multi-physiological functions including effect such as a health-promoting functional compound. To improve the GABA production, Chlorella protothecoides were grown through the modified mixtrophic culture medium containing 2L of sterilized bristol medium with 0.01% urea and 4.0% glucose in a 5L fermenter. The results showed that nineteen kinds of amino acid including GABA at C. protothecoides sample were analyzed using high performance liquid chromatography (HPLC). Glutamic acid in total concentration (%) of amino acid is the most abundant amino acid (33.10%), followed by alanine (20.48%) and GABA (17.48%). Three amino acids including GABA were responsible for more than 70% total concentration in C. protothecoides sample including eight essential and nine non-essential amino acids: aspartic acid, asparagine, serine, glutamine, histidine, glycine, threonine, arginine, tyrosine, valine, methionine, tryptophan, phenylalanine, isoleucine, leucine, lysine. As a result of this experiment, it is expected that Chlorella will be developed to a critical product having high value as, GABA, functional food materials.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6B
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• pp.568-574
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• 2009

320km optical transmission link for 128 channel DWDM (dense wavelength-division-multiplexing) signals is simulated and fabricated. An optical fiber amplifier for the link is composed of a distributed Raman amplifier and dual C/L-band EDFAs which are optimized for the performances of an optical amplifier obtained from the simulation. Gain and NF of the optimized EDFAs are above 19dB and below 7.5dB, respectively. The resultant OSNRs (optical signal to noise ratios) of the link are average 25dB on each band.

• Journal of Species Research
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• v.9 no.1
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• pp.46-55
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• 2020

Chrysosplenium grayanum Maxim. (Series Nepalensia), which had been known to be restricted to Japan, was newly discovered from Mt. Cheongtae in Yeonggwang-gun, Jeollanam-do, located in the southern part of the Korean Peninsula. Species identification was confirmed using morphological characteristics and DNA sequence data, while comparing with materials obtained from Japan and herbarium specimens. Chrysosplenium grayanum is clearly distinguished from the remaining taxa of the genus Chrysosplenium by having glabrous plant body, opposite leaves, cylindrical papillae with roundish head at the tip on the smooth seed surface, and four stamens. Molecular sequence data of the nuclear ribosomal ITS regions, chloroplast rbcL and matK genes strongly supported that this previously unknown Chrysosplenium species from Korea is C. grayanum. Taking the molecular and the morphological evidence into consideration, it is clear that newly discovered Chrysosplenium population in Korea is conspecific with the widely distributed C. grayanum in Japan. In this paper, we provide a description, illustration, and photo images of Chrysosplenium grayanum from Korea and also a key to the Chrysosplenium species in Korea.