• Title, Summary, Keyword: cluster analysis

Search Result 4,474, Processing Time 0.076 seconds

Community Structure of the Macrobenthos in the Soft Bottom of Yongsan River Estuary, Korea 2. The Occurrence of Summer Hypoxia and Benthic Community (영산강 하구역의 연성저질에 서식하는 저서동물 군집 2. 여름철 빈산소 수괴의 출현과 저서동물 분포)

  • LIM Hyun-Sig;PARK Kyung-Yang
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.31 no.3
    • /
    • pp.343-352
    • /
    • 1998
  • The relationship between summer hypoxia in bottom water layer and benthic community structure was discussed at forty sampling stations in semi-enclosed Youngsan River estuarine bay, Korea. The oxygen deficient layer less than $2.0 mg/\ell$ was widely developed in the inner estuarine stations in summer due to the summer stratification. A total of 141 species was occurred, with a mean density of $1,923 ind./m^2$ and biomass of $79.44\;g/m^2$ in summer season. The species number was significantly increased with the increment of the bottom dissolved oxygen, whereas density and biomass were partially correlated within the low oxygen level of $2.0\;mg/\ell$. These results imply that benthic community structures are affected by bottom oxygen depletion in summer. Cluster analysis showed that the benthic community could be classified into three station groups. These station groups from the species composition coincided with the groups based on the environmental factors. This fact suggests that the overall spatial distribution of macrozoobenthos in Youngsan River estuarine bay in summer should be controlled by the summer hypoxia and clay content of the area. Group-I was located the innermost estunrine bay from Mokpo Harbour to near the dike, where summer hypoxia was developed and one bivalve Theora fragilis, two polychaetes, Tharyx sp. and Lumbrineris longifolia were dominated. Group-II, the central transitory area of the estuarine bay between two another stational groups, where two bivalves Theora fragilis, Raetellops pulchella and a polychaete Tharyx sp. predominated with relatively low density compared to that of Group-I. Group-III, the mouth part of the estunrine bay exposed to the open sea, where a polychaetes Poecilochaetus johnsoni and a bivalve Yoldia Johanni predominated.

  • PDF

A PRELIMINARY STUDY OF RELATIONSHIP AMONG TEMPERAMENTAL CHARACTERISTICS, FAMILY ENVIRONMENT AND DEVELOPMENTAL HISTORY (기질과 가정환경 및 발달사이의 관계에 관한 예비연구)

  • Hong, Sung-Do
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
    • /
    • v.8 no.1
    • /
    • pp.50-56
    • /
    • 1997
  • The objective of this study was to compare the family environment and developmental history of three groups of children classified by their temperament. The parents of 484 Korean children aged between 3 and 7 years completed the Korean version of Parental Temperamental Questionnaire developed by Thomas and Chess and Developmental Questionnaire created by Division of Child and Adolescent Psychiatry, Samsung Medical Center. After clustering these children into 5 temperamental groups according to the method proposed by Fullard et al, 98 Easy, 36 Difficult, and 21 Slow-To-Warm-Up children were included in the analysis. Statistically meaningful differences observed among three groups were as follow:1) Marital conflict of parents was more frequent in Difficult and Slow-To-Warm-Up children than in Easy children. 2) Parentchild conflict was more frequent in Difficult children than in Easy children. 3) Conflict among siblings was more frequent in Difficult children than in Easy children. 4) Average monthly income of family was less in Difficult children than in Easy children. 5) Toilet training was achieved later in Difficult children than in Easy children. 6) Motor development was slower, between 2 and 5 years old, in Slow-To-Warm-Up children than in Easy children. 7) Fear of stranger started earlier in Slow-To-Warm-Up children than in easy children. 8) Physical health was poorer in Difficult and Slow-To-Warm-Up children than in easy children. The findings indicate that Difficult child or Slow-To-Warm-Up child group have unfavorable family environment, different developmental milestone and poorer physical health in comparison with Easy child group.

  • PDF

Community Structure of Macrobenthos in the Subtidal Soft Bottom in Semi- enclosed Youngsan River Estuarine Bay, Southwest Coast of Korea (반폐쇄적인 영산강 하구역 조하대 연성저질의 저서동물 군집)

  • LIM Hyun-Sig;PARK Kyung-Yang
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.32 no.3
    • /
    • pp.320-332
    • /
    • 1999
  • Investigations were made on the community structure of macrobenthos in the subtidal soft bottom around semi-enclosed Youngsan River estuarine bay, southwest coast of Korea during the period from April 1995 to February 1996. Three macrobenthos samples were collected at 40 stations using a van Veen grab(0.1 m^2) during the study period. A total of 206 species of macrobenthos was identified. Their mean density and biomass (wet-weight, wwt) were $1,137 ind./m^2$ and $65.28 gwwt/m^2$, respectively. Of these, there were 74 species of polychaetes ($36\%$), 60 molluscs ($39\%$), 51 crustaceans ($25\%$) and 21 miscellaneous taxa. Molluscs were represented as a density- and biomass-dominant faunal group with a mean density of $601 ind./m^2$($53\%$ of the total benthic animals) and biomass of $25.37 gwwt/m^2$($39\%$ of total biomass): It was followed by polychaetes with $405 ind./m^2$($40\%$ of the total density). Total number of species and diversity were Bow in the inner estuarine bay containing high mud content and organic matter, whereas they were high in the outer stations containing low mud content and organic matter. Major dominant species were one biralve, Theora fragilis and three Polychaetes, Tharyx sp., Poeciloceatus johnonni and Lumbrineris lontifolia whose mean densities were $490ind./m^2$, $96ind./m^2$, $74ind./m^2$and $52 ind./m^2$, respectively. Cluster analysis indicated that the study area could be divided into four station groups: two innermost station groups, a central bay and an outer station group. The species diversity increased from the inner station group toward the outer groups. These results were discussed in terms of both the environmental factors and distribution of benthic community.

  • PDF

Marine Environments and Ecological Characteristics of Phytoplankton in Southern Coastal Waters During June to October in 2004-2006 (2004-2006년 6-10월 동안의 남해중부연안 해역특성 및 식물플랑크톤의 군집생태)

  • Cho, Eun-Seob;Lee, Sang-Yong;Kim, Sang-Soo;Choi, Yoon-Seok
    • Journal of Environmental Science International
    • /
    • v.16 no.8
    • /
    • pp.941-957
    • /
    • 2007
  • This study monitored marine environments and ecological characteristics of phytoplankton in southern coastal waters during June to October in 2004-2006 and provided an information to how Cochlodinium blooms have occurred. A total of sampling sites was 16 (Dukyang bay, Goheung, Yeoja bay, Gamak bay, Gwangyang bay, Yeosu, and Namhae). Temperature ranged from $19^{\circ}C\;to\;29^{\circ}C$, which all of sampling in Yeoja bay was the highest temperature of $27^{\circ}C\;and\;29^{\circ}C$ during summer. On June, July, September, and October did not show a remarkable difference regardless of sampling sites. Yeoja and Gwangyang bays had 25-27 in salinity that was lower approximately 5-6 compared with other sampling sites. Chlorophyll had considerable fluctuations depending on sampling sites on July and October, in particular, Gwangyang bay was the highest value of $15{\mu}gl^{-1}$ that had five times as much as. Unlikely to temperature, salinity, and chlorophyll, transparency ranged from 2 m to 5 m regardless of sampling sites. Gwangyang bay was the highest DIN (Dissolved Inorganic Nitrogen) of $0.53mgl^{-1}$ on July and August that had ten times as much as, whereas DIP (Dissolved Inorganic Phosphorus) did not show a significant difference between sampling sites. On July, the correlation of DIN and chlorophyll was a negative that should extremely require DIN to grow phytoplankton, but was a positive liner on August. Mean cell number of phytoplankton reached to encounter a peak of 500 cells $ml^{-1}$ in July and August, which diatoms were dominant species and attained an abundance of >60% regardless of months. In August, the occurrence of dinoflagellates ranged from 20% to 30%. Skeletonema costatum, one of dominant speicies, was the highest occurrence to throughout sampling sites during 2004 to 2006. On the basis of cluster analysis for phytoplankton, they were distributed in all of sampling sites. Consequently, significant fluctuations of marine environments were shown in summer and S. costatum was regarded as the representive phytoplankton in southern coastal waters. In particular, the outbreaks of Cochlodinium polykrikoides have occurred in Dukyang bay, Gamak bay, Goheung, Yeosu, and Namhae, but Yeoja and Gwangyang bays did not occur. The distinguish characteristics of occurring sampling sites and non-occurring in Cochlodinium blooms based on this study was DIN that was enough to persistently grow and maintain them even a litter dissolved in water. This suggests that Cochlodinium red tide seems to be occur in off waters.

Ecological Niche of Quercus acutissima and Quercus variabilis (상수리나무와 굴참나무의 생태적 지위에 관한 연구)

  • Kim, Hae-Ran;Jeong, Heon-Mo;Kim, Hyea-Ju;You, Young-Han
    • Korean Journal of Environmental Biology
    • /
    • v.26 no.4
    • /
    • pp.385-391
    • /
    • 2008
  • In Korea, Quercus acutissima distributed in good condition with high nutrients and moisture content, but Quercus variabilis in dry soil or rock habitate. In order to understand this ecological distribution of Q. acutissima and Q. variabilis, we cultivated the seedlings of two oak species treated with light, soil moisture and nutrient gradients each four level, from May to October in glass house. Then we measured the ecological niche breadth and niche overlap of the two species, and analyzed the relationship of competition using cluster analysis and PCA ordination. Ecological niche breadths of Q. acutissima under moisture and nutrient treatments were slightly wider than those under light one. Among 14 characters measured, 6 characters related with length items were wider in all the environmental treatments, but 8 characters connected with weight terms narrower in light treatment. Ecological niche breadths of Q. variabilis under moisture and nutrient treatment were wider than those of light one. Ecological niche of Q. acutissima was wider than those of Q. variabilis in all the environmental treatments. Ecological overlap between two species was higher with a range of 0.87$\sim$0.92, especially higher in soil moisture factor. These results means that Q. acutissima is more competitive than Q. variabilis, especially in soil moisture condition. Two species were ordinated with distinct group based on 9 characters. From these results, it can be explained that what Q. variabilis distributed in bad soil condition is due to the escape strategy, because of its low competitive ability to Q. acutissima in natural communities.

Association between Periodontitis and Coronary heart disease in Korea : Inflammatory markers and IL-1 gene polymorphism (한국인에서 치주질환과 관상동맥질환의 관련성에 대한 염증표지자와 IL-1 유전자 다변성의 영향)

  • Jeong, Ha-Na;Chung, Hyun-Ju;Kim, Ok-Su;Kim, Young-Joon;Kim, Ju-Han;Koh, Jung-Tae
    • Journal of Periodontal and Implant Science
    • /
    • v.34 no.3
    • /
    • pp.607-622
    • /
    • 2004
  • Recently epidemiologic studies have indicated that the patients with periodontitis may have increased risk of ischemic cardiovascular events, and have suggested the important roles of blood cytokines and acute reactant proteins in the systemic infection and inflammatory response. Periodontitis and coronary heart disease (CHD) may share the common risk factors and the genetic mechanism associated with interleukin(IL)-1A, B and RA genotype may be involved in the production of IL-1. This study was aimed to investigate the relationship between angiographically defined CHD and periodontitis as chronic Gram-negative bacterial infection and to determine whether the IL-1 gene polymorphism is associated in both diseases. Patients under the age of 60 who had undergone diagnostic coronary angiography were enrolled in this study. Subjects were classified as positive CHD (+CHD, n=37) with coronary artery stenosis more than 50% in at least one of major epicardial arteries, and negative CHD (-CHD, n=30) without significant stenosis. After recording the number of missing teeth, periodontal disease severity was measured by means of plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL), and radiographic bone loss around all remaining teeth. Gingival crevicular fluid (GCF) was collected from the 4 deepest periodontal pockets and assessed for cytokine ($IL-1{\beta}$, IL-6, IL-1ra, tumor necrosis $factor-{\alpha}$, and prostaglandin $E_2$). Additionally, blood CHD markers, lipid profile, and blood cytokines were analyzed. IL-1 gene cluster genotyping was performed by polymerase chain reaction and enzyme restriction using genomic DNA from buccal swab, and allele 2 frequencies of IL-1A(+4845), IL-1B(+3954), IL-B(-511), and IL-1RA(intron 2) were compared between groups. Even though there was no significant difference in the periodontal parameters between 2 groups, GCF level of $PGE_2$ was significantly higher in the +CHD group(p<0.05). Correlation analysis showed the positive relationship among PD, CAL and coronary artery stenosis(%) and blood $PGE_2$. There was also significant positive relationship between the periodontal parameters (PI, PD, CAL) and the blood CHD markers (leukocyte count, C-reactive protein, and lactic dehyrogenase). IL-1 gene genotyping showed that IL-1A(+3954) allele 2 frequency was significantly higher in the +CHD group compared with the -CHD group (15% vs. 3.3%, OR 5.118,p=0.043). These results suggested that periodontal inflammation is related to systemic blood cytokine and CHD markers, and contributes to cardiovascular disease via systemic inflammatory reaction. IL-1 gene polymorphism might have an influence on periodontal and coronary heart diseases in Korean patients.

Health Related Lifestyle and Stress Among Inhabitants of a City in Korea (일부 도시지역 주민들의 일상생활습관과 스트레스와의 관련성)

  • 손철준;조영채
    • Korean Journal of Health Education and Promotion
    • /
    • v.21 no.2
    • /
    • pp.17-32
    • /
    • 2004
  • The purpose of this study was to evaluate the patterns of stresses arising from various life styles and their related sociodemographic factors in urban residents. The subjects were recruited from the population of two ‘Dong’s (administrative blocks) representative of Daejeon city through stratified cluster random sampling during the period ranging from June I st to Aug. 31 st, 2003. Self-administered questionnaires, including items asking about subjects' sociodemographic characteristics, daily life styles, measurement of stresses by General Health Questionnaire (Goldberg, 1978), were delivered to 396 residents and their responses were analyzed with the following results. 1. Based on the discriminant scores of HPI, 46.7% of the subjects were found to have less than 4 points (poor life style), whereas 53.3% had points higher than 5 (good life style). Higher than 5 points were scored more frequently in females than in the male, in the age group of 40's - 60's than the 30's, in the group with spouse than without, in the group with both spouse and offsprings than without, and in the group owning a house than not. 2. Based on the degree of stress, 17.7% of the subjects were determined to be healthy, 74.5% were potentially under stress, and 7.8% were at higher risk of stress. The proportion of healthy individuals were significantly higher in the male, advanced aged group(40's and 60's), the group with higher education years( over highschool), with higher monthly income over two million Won, and with spouse, than their respective counterparts. On the other hand the proportion of the individuals potentially under stress and at higher risk of stress was significantly higher in the female, in the age group of 30's and over 60's, in the group with academic career lower than middle school, with monthly income lower than two million Won, and without spouse. 3. Based on the relation of HPI with degree of stresses, subjects with HPI scores lower than 4 had increased rate of falling into the groups under potential stress and at higher risk of stress, while on the other hand those with over 5 points were found to be healthy in light of stress. 4. Based on the specific relation of each item of HPI with degree of stress, the proportion of healthy individuals was higher in the groups who take appropriate hours of sleep(7-8hours), who take breakfasts everyday, who take physical exercises everyday, who don't smoke, who don't drink alcohol, who take snacks everyday, who are overweight and obese, whereas the proportion of the group under potential stress and at higher risk of stress was higher in their comparable counterparts. 5. The relation of mean scores of HPI with stress scores in both male and female subjects showed negative correlation that the higher HPI scores, the lower stress scores. 6. Multivariate regression analysis to reveal the factors influencing the stress of the subjects showed that for men the significant factors were age, education, presence of job or not, exercise, subjective health status, with the explanatory power of 26.3%. For women, they included educational years, presence of spouse or not, job, owning a house or not, sleeping hours, drinking habit, taking snacks, subjective health status, with the explanatory power of 31.8%. The above study results suggests that stresses of urban residents have significant correlation with daily life styles and this correlation is also remarkably distinguished by different age and sex.

Distribution of Benthic Macrofauna in subtidal area and on sand flat of Sindu-ri coast, Korea (신두리 해안의 조하대와 모래 갯벌에 서식하는 대형저서동물의 분포)

  • Koo, Bon Joo;Shin, Sang Ho;Woo, Han Jun
    • Journal of Wetlands Research
    • /
    • v.7 no.2
    • /
    • pp.69-88
    • /
    • 2005
  • Distribution of benthic macrofauna was surveyed in the subtidal area and on the sand flat of Sindu-ri coast during July 2002. A total of 134 species, 3,511 individuals and 388g biomass of macrobenthos were sampled inclusively from the study sites. 109 species with a mean density of $1,298ind./m^2$ and biomass of $69.4g/m^2$ were collected from 10 stations established in the subtidal area. Polychaetes were represented as a dominant faunal group of the subtidal area in both species richness and density with values of 54 species and $813ind./m^2$. Cluster analysis based on the faunal composition showed that the subtidal area could be divided into four stational groups according to sedimentary characteristics: Cirrophorus armatus - Lumbrineris longifolia association on the mud sediment with pebbles near aqua-farms; Aonides oxycephala association on the rocky bed; Scoloplos armiger - Grandifoxus cuspis association on the sand-dominated sediment along the lowest low water; a association with higher evenness on the sand-dominated sediment in the depth. Although having characteristics of high value in species richness, density and species diversity, the macrobenthic association around the farming area was dominated by the opportunistic species such as Lumbrineris longifolia and Tharyx sp. Natural community represented by S. armiger and G. cuspis was developed in most sand-dominated areas. 50 species were sampled with a mean density of $2,443ind./m^2$ and biomass of $381.3g/m^2$ from eight+ stations along two transects on Sindu-ri sand flat. Mollusks were represented as a dominant faunal group of the sand flat in species richness, density and biomass with values of 20 species, $1,345ind./m^2$ and $350.4g/m^2$, respectively. Umbonium thomasi, Veneridae sp., Mandibulophoxus mai, Armandia lanceolata, Eohaustorius spinigerus, Urothoe convexa were dominant species and these species accounted for over 83% of total individuals. There were three distinct zones of macrobenthos on Sindu-ri sand flat according to the extent of exposure time. The upper zone was dominated by Scopimera globosa, the middle zone was characterized by M. mai, and the lower zone was dominated by E. spinigerus. Sindu-ri coastal area was considered as a healthy habitat for macrobenthos, except for around the farming area. It was considered that Sindu-ri coastal area including the sand flat connected to the sand dune of natural monument was a valuable habitat as a protected site in having no pollution source and no artificial structure.

  • PDF

DENTAL CARIES STATUS AND RELATED FACTORS AMONG DISABLED CHILDREN AND ADOLESCENT IN KOREA (우리나라 소아.청소년 장애인의 치아우식증 실태와 관련요인)

  • Jeong, Seong-Hwa;Kim, Ji-Young;Park, Ji-Hye;Choi, Youn-Hee;Song, Keun-Bae;Kim, Young-Jin
    • THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
    • /
    • v.35 no.1
    • /
    • pp.102-109
    • /
    • 2008
  • The aims of this study were to evaluate dental caries status and to analyze the dental caries related factors which could explain the relationship between dental caries and disabled type, severity of handicap, and oral health behaviors among disabled children and adolescent in Korea. A total of 677 subjects aged from 6 to 18 were finally selected by stratified cluster sampling. They were examined by 13 trained dentists and interviewed with questionnaire. For the crude and adjusted associations, bivariate and multivariate analysis were performed using SPSS program(SPSS Inc, Chicago, USA). DMFT index were 0.90(ages 6-8), 2.32(ages 9-11), 3.63(ages 12-14) and 4.93(ages 15-17), respectively. The DMFT index was significantly related to age, frequency and dependency of toothbrushing, and mastication and functional disorder. Specialized preventive care program which accounted the age and toothbrushing instruction be developed and adapted to promote oral health status and behaviors of disabled children and adolescent in Korea.

  • PDF

Evaluation of Germplasm and Development of SSR Markers for Marker-assisted Backcross in Tomato (분자마커 이용 여교잡 육종을 위한 토마토 유전자원 평가 및 SSR 마커 개발)

  • Hwang, Ji-Hyun;Kim, Hyuk-Jun;Chae, Young;Choi, Hak-Soon;Kim, Myung-Kwon;Park, Young-Hoon
    • Horticultural Science & Technology
    • /
    • v.30 no.5
    • /
    • pp.557-567
    • /
    • 2012
  • This study was conducted to achieve basal information for the development of tomato cultivars with disease resistances through marker-assisted backcross (MAB). Ten inbred lines with TYLCV, late blight, bacterial wilt, or powdery mildew resistance and four adapted inbred lines with superior horticultural traits were collected, which can be useful as the donor parents and recurrent parents in MAB, respectively. Inbred lines collected were evaluated by molecular markers and bioassay for confirming their disease resistances. To develop DNA markers for selecting recurrent parent genome (background selection) in MAB, a total of 108 simple sequence repeat (SSR) primer sets (nine per chromosome at average) were selected from the tomato reference genetic maps posted on SOL Genomics Network. Genetic similarity and relationships among the inbred lines were assessed using a total of 303 polymorphic SSR markers. Similarity coefficient ranged from 0.33 to 0.80; the highest similarity coefficient (0.80) was found between bacterial wilt-resistant donor lines '10BA333' and '10BA424', and the lowest (0.33) between a late blight resistant-wild species L3708 (S. pimpinelliforium L.) and '10BA424'. UPGMA analysis grouped the inbred lines into three clusters based on the similarity coefficient 0.58. Most of the donor lines of the same resistance were closely related, indicating the possibility that these lines were developed using a common resistance source. Parent combinations (donor parent ${\times}$ recurrent parent) showing appropriate levels of genetic distance and SSR marker polymorphism for MAB were selected based on the dendrogram. These combinations included 'TYR1' ${\times}$ 'RPL1' for TYLCV, '10BA333' or '10BA424' ${\times}$ 'RPL2' for bacterial wilt, and 'KNU12' ${\times}$ 'AV107-4' or 'RPL2' for powdery mildew. For late blight, the wild species resistant line 'L3708' was distantly related to all recurrent parental lines, and a suitable parent combination for MAB was 'L3708' ${\times}$ 'AV107-4', which showed a similarity coefficient of 0.41 and 45 polymorphic SSR markers.