• Journal of the Korean Ceramic Society
• /
• v.33 no.2
• /
• pp.177-182
• /
• 1996

strontium titanate (SrTiO3) thin films deposited on Pt/MgO were prepared by Plasma Enhanced Metal Orgainc Chemical vapor Deposition (Pe-MOCVD). The crystallinity of SrTiO3 thin films increased with increasing depo-sition temperature and SrF2 second phase disappeared at 55$0^{\circ}C$ The films showed a dielectric constant of 177 and a dissipation factor of 0.0195 at 100 kHz. The variation of capacitance of the films with applied voltage was small showing paraelectric properties. The charge storage density and leakage current density were 40fC/${\mu}{\textrm}{m}$2 and 3.49$\times$10-7 A/cm2 at 0.25 MV/cm, respectively.

• Journal of Korean Society of Forest Science
• /
• v.103 no.4
• /
• pp.519-527
• /
• 2014

Deutzia paniculata is an endemic species, which is geographically restricted within southern part of Korea. Four populations of D. paniculata were sampled across its natural range, from the smallest population, Mt. Dalum, which held less than 100 individuals, to the largest, Mt. Unmum, over 3,500 individuals. Artificial pollination study showed that D. paniculata had an obligate outcross breeding system. Major pollinators were two bee species, Lasioglossum exiliceps and Allograpta balteata (de Geer). The breeding system and patterns of allozyme variation of D. paniculata were investigated to understand the population biology and to explain on reserve designs and management proposals relevant to this species. D. paniculata held relatively low genetic variation at the eight allozyme loci surveyed. Measures of genetic variation in this species alleles per locus ($A_s=1.33$), proportion of polymorphic loci (P=23.85%), and expected heterozygosity ($H_{es}=0.110$) were similar to values reported for endemic species. Mt. Dalum population (DAL) was composed with one clone based on allozyme data. Individuals of D. paniculata were frequently included in root connected clusters. Population genetic structure between and within four populations was probably the result of shrinking effective population size and the extinctions of intervening populations. For the conservation of genetic diversity, maximum number of different genotype need to be protected based on genetic structure and mating system.

• Journal of IKEEE
• /
• v.18 no.1
• /
• pp.37-44
• /
• 2014

In this paper we present an LDO based on an error amplifier. The designed error amplifier has a gain of 89.93dB at low frequencies. This amplifier's Bandwidth is 50.8MHz and its phase margin is $59.2^{\circ}C$. Also we proposed a BGR. This BGR has a low output variation with temperature and its PSRR at 1 KHz is -71.5dB. For a temperature variation from $-40^{\circ}C$ to $125^{\circ}C$ we have just 9.4mV variation in 3.3V LDO output. Also it is stable for a wide range of output load currents [0-200mA] and a $1{\mu}F$ output capacitor and its line regulation and especially load regulation is very small comparing other papers. The PSRR of proposed LDO is -61.16dB at 1 KHz. Also we designed it for several output voltages by using a ladder of resistors, transmission gates and a decoder. Low power consumption is the other superiority of this LDO which is just 1.55mW in full load. The circuit was designed in $0.35{\mu}m$ CMOS process.

• Journal of Korean Society of Forest Science
• /
• v.98 no.5
• /
• pp.531-538
• /
• 2009

We used enzyme electrophoresis to evaluate genetic diversity in five populations of endemic ash, Fraxinus chiisanensis in Korea. Of 15 putative allozyme loci examined 26.7% were polymorphic and expected heterozygosity for the species was low (0.082). Within the range, population were highly differentiated ($F_{ST}$=0.356) and little genetic variation was explained by geography. The pattern of distribution of variation showed low genetic variation within populations and pronounced divergence among populations, which was consistent with the prediction for the effects of limited gene flow and local genetic erosion. Although the frequencies of male plants were dominant ranging from 79.3% to 89.4%, most mating events seems to be inevitable mating between relatives in small populations based on heterozygote deficiency of this species. Small effective population size and the limited dispersal contributed to the low rates of gene flow within as well as between populations.

• Korean Journal of Plant Taxonomy
• /
• v.46 no.4
• /
• pp.361-370
• /
• 2016

An area comprising Juwangsan National Park and its adjacent mountains (southeastern Korean Peninsula) is a good model system for testing the effects of physical barriers to gene flows in plant populations. We predicted that plant species consisting of isolated populations are genetically more differentiated than those that are rather continuously distributed. Most populations of Sedum polytrichoides occur in four isolated valleys, and we assessed the genetic variability and structures using twelve allozyme loci in ten populations. We also compared the present results to earlier findings pertaining to the two co-occurring herbs Hylotelephium ussuriense (${\equiv}$ Sedum ussuriense) (growing only in the four isolated valleys) and S. kamtschaticum (rather continuously distributed). We found moderate levels of within-population genetic variation in S. polytrichoides ($H_{e}=0.112$). Estimates of among-population divergence in S. polytrichoides were also moderate ($F_{ST}=0.250$) and, as expected, very similar to that of H. ussuriense (0.261) but considerably higher than the variation in S. kamtschaticum (0.165). An analysis of molecular variance (AMOVA) revealed that S. polytrichoides and H. ussuriense had higher percentages of among-valley variation (19% each) than S. kamtschaticum (4%). Most of this variation, as also indicated by the STRUCTURE program, was due to differences in genetic profiles between the two central valleys. We concluded that the genetic differences observed between species (S. kamtschaticum vs. S. polytrichoides and H. ussuriense) are mainly due to differences in their distribution within the study area.

• Korean Journal of Environmental Biology
• /
• v.36 no.4
• /
• pp.463-470
• /
• 2018

Restoration ecology is the practical study of renewing and restoring a spoilt, degraded, or devastated ecosystems in the environment. Because the Korean industry has been drastically developed for the past few decades, the Korean ecosystem requires restoration using regional seed. In this study, we identified the variation of phylogenic relationship of Miscanthus sinensis or Phragmites australis by locations in Korea. Chloroplast DNA atpF-H and psbA-trnH interspace region were used as a molecular marker to resolve the phylogenic relationship in 10 different locations. We performed the molecular phylogenetic analysis with 10 chloroplast DNAs from each location using Kimura 2-parameter. The analysis of Miscanthus showed that all atpF-H genes were exact matches except for Ose san. In contrast to Mischanthus, the atpF-H genes from Phragmites were observed to have more variation. A total of 7 locations revealed the variation in chloroplast gene. According to the phylogenic tree in Phragmites, 2 of 10 samples in 6 locations and 3 of 10 in 1 location showed variation with 0.160-0.181 genetic distance. According to the genetic distance of the Miscanthus sinensis, there were no mutations in all regions except the Hongsung. These results support regional differences and show the necessity for seed collection by region. In the case of Phragmites australis, genetic variation occurred in all regions.

• Applied Biological Chemistry
• /
• v.45 no.1
• /
• pp.30-36
• /
• 2002

A bioconcentration experiment was performed for killifish using nonradioactive and radioactive butachlor. At 0.036 ppm concentration, the highest bioconcentration ratio $(C_f/C_w)$ and BCF at steady state recorded as 296 and 87 respectively. And at 0.0036 ppm concentration, the highest $C_f/C_w$ ratio was 169 and the BCF was 51 at steady state. Considering the experimental variation of the BCF's, the BCF of butachlor was tentatively determined to be $69{\pm}28$. And the $^{14}C-butachlor$ and its metabolites depurated about 50% within 12 hours and 90% within 30 hours after depuration experiment started. And in vivo metabolites, designated as M-I, M-II, and M-III, were found in killifish and the excretes as butachlor was metabolised.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.8 no.1
• /
• pp.44-48
• /
• 1997

Anatomic and physiological changes of the larynx with advancing age result in morphologic changes of the vocal fold and reduced control of the phonatory mechanism in elderly individuals and are reflected in increased unstability of fundamental frequency (Fo). The purpose of this study is to increase current understanding of acoustic and stroboscopic characteristics of normal elderly persons voices. First, phonated /a/ vowel productions by 40 normal adults (20 to 40 years, 20 men and 20 women) and 40 normal elderly persons (60 to 80 years,20 men and 20 women) were analyzed, using CSL (model 4300B) acoustic analysis software, to obtain acoustic measures related to fundamental frequency stability nd vocal resonance characteristics. Second, stroboscopic images of the vocal fold behavior in all subjects were analyzed by experienced specialists. In the men, fundamental frequency variation (vFe) (p＜0.01), jitter. (p＜0.05), and shimmer (p＜0.05) for the older group were significantly higher than the value for the adult group. In the stroboscopic findings, edema of vocal fold had a significant finding in aged men (15%). In the women, vFo (p＜0.05), jitter (p＜0.05), and noise to harmonic ratio (NHR) (p＜0.05) for the older group were significantly higher than the value for e adult group and first formant frequency (F1) (p＜0.01) and second formant frequency (F2) (p＜0.01) for. the older group were significantly lower than the value for the adult group. In the stroboscopic findings, vocal fold atrophy had a significant finding in aged women (25%). Frequency stability, as reflected by vFo, jitter, shimmer, and NHR, decreases with advancing age in men and women and spectral analysis of phonated /a/ vowel productions reveals the lowering of the frequency of F1 and second F2 with advancing age, especially in aged women. Change in the mass of vocal folds, due to atrophy or edema, is considered to be the greatest factor in these acoustic changes.

• Asian-Australasian Journal of Animal Sciences
• /
• v.25 no.2
• /
• pp.170-176
• /
• 2012

Genetic diversities, population genetic structures and demographic histories of the thread-sail filefish Stephanolepis cirrhifer were investigated by nucleotide sequencing of 336 base pairs of the mitochondrial DNA (mtDNA) control region in 111 individuals collected from six populations in Korean coastal waters. A total of 70 haplotypes were defined by 58 variable nucleotide sites. The neighbor-joining tree of the 70 haplotypes was shallow and did not provide evidence of geographical associations. Expansion of S. cirrhifer populations began approximate 51,000 to 102,000 years before present, correlating with the period of sea level rise since the late Pleistocene glacial maximum. High levels of haplotype diversities ($0.974{\pm}0.029$ to $1.000{\pm}0.076$) and nucleotide diversities (0.014 to 0.019), and low levels of genetic differentiation among populations inferred from pairwise population FST values (-0.007 to 0.107), support an expansion of the S. cirrhifer population. Hierarchical analysis of molecular variance (AMOVA) revealed weak but significant genetic structures among three groups ($F_{CT}$ = 0.028, p<0.05), and no genetic variation within groups (0.53%; $F_{SC}$ = 0.005, p = 0.23). These results may help establish appropriate fishery management strategies for stocks of S. cirrhifer and related species.

• Journal of Korean Society of Forest Science
• /
• v.99 no.5
• /
• pp.686-692
• /
• 2010

This study described the general pattern of genetic variation among ten teak (Tectona grandis Linn. f.) provenances in Myanmar and determined the most suitable seed sources for the plantation program in Bago Yoma region. Seeds of ten provenances were collected to cover the whole teak natural distribution in Myanmar and planted at four trial sites in Bago Yoma region in 1998. Seven years after planting, variation was assessed for growth, morphological characteristics and their correlation with geoclimatic factors. Statistical analysis using ANOVA revealed that there were significant differences in most of the traits measured among provenances, trial sites and provenance ${\times}$ site interaction at five percent level. A positive significant correlation (p<0.01) was found among most of the traits. The regression analyses between all traits and geoclimatic factors indicated the existence of ecoclinal variation in teak. Most of the traits were negatively correlated with the latitude while a positive significant correlation was found between longitude and C/B ratio, crown-diameter, average branch angle and leaf-remain. There was no significant correlation between the mean temperature and any other traits in this study. Furthermore, growth traits and crown diameter were positively correlated with the mean annual rainfall while negative correlation was found between the geographical distance and growth traits. Results indicate that the latitudinal pattern of teak genetic variations in growth performance was attributed to the limit of mean annual rainfall. Comparative assessment showed that local provenances were generally the best and could be use as suitable seed sources for the plantation program in the Bago Yoma region.