• Title/Summary/Keyword: dominant period

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Short-term Variations in Community Structure of Phytoplankton and Heterotrophic Protozoa during the Early Fall Phytoplankton Blooms in the Coastal Water off Incheon, Korea (인천 연안의 초가을 식물플랑크톤 대증식기에 식물플랑크톤과 종속영양 원생동물 군집의 단주기 변동)

  • Yang, Eun-Jin;Choi, Joong-Ki
    • Ocean and Polar Research
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    • v.29 no.2
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    • pp.101-112
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    • 2007
  • In order to examine the short-term variations of phytoplankton and heterotrophic protozoa community structures with bloom events, water samples were collected every other day at one site in the coastal water off Incheon, Korea, from August 15-September 30, 2001. $Chlorophyll-{\alpha}$ concentrations varied widely from 1.8 to $19.3\;{\mu}g\;l^{-1}$ with the appearances of two major peaks of $Chlorophyll-{\alpha}$ concentration during the study period. Size-fractionated $Chlorophyll-{\alpha}$ concentration showed that net-size fraction ($>20\;{\mu}m$) comprised over 80% of total $Chlorophyll-{\alpha}$ during the first and second bloom periods, nano-size fraction ($3{\sim}20\;{\mu}m$) comprised average 42% during the pre- (before the first bloom) and post-bloom periods (after the second bloom), and pico- size fraction ($<3\;{\mu}m$) comprised over 50% during inter-bloom periods (i.e. between the first and second bloom periods). Dominant phytoplankton community was shifted from autotrophic nanoflagellates to diatom, diatom to picophytoplankton, picophytoplankton to diatom, and then diatom to autotrophic nanoflagellates, during the pre-, the first, the inter, the second, and the post-bloom periods, respectively. During the blooms, Chaetoceros pseudocrinitus and Eucampia zodiacus were dominant diatom species composed with more than 50% of total diatom. Carbon biomass of heterotrophic protozoa ranged from 8.2 to $117.8\;{\mu}gC\;l^{-1}$ and showed the highest biomass soon after the peak of the first and second blooms. The relative contribution of each group of the heterotrophic protozoa showed differences between the bloom period and other periods. Ciliates and HDF were dominant during the first and second bloom periods, with a contribution of more than 80% of the heterotrophic protozoan carbon biomass. Especially, different species of HDF, thecate and athecate HDF, were dominant during the first and the second bloom periods, respectively. Interestingly, Noctiluca scintillans appeared to be one of the key organisms to extinguish the first bloom. Therefore, our study suggests that heterotrophic protozoa could be a key player to control the phytoplankton community structure and biomass during the study period.

Comparison of Growth Characteristics of Creeping Bentgrass(Agrostis palustris Huds.) Cultivars in Summer (하절기 크리핑 벤트그래스의 품종별 특성비교)

  • Tae, Hyun-Sook;Lee, Hyung-Seok;An, Kil-Man;Kim, Jong-Bo
    • Asian Journal of Turfgrass Science
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    • v.20 no.2
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    • pp.147-156
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    • 2006
  • This study was initiated to evaluate the growth characteristics of seven creeping bentgrass cultivars in summer, 'Penncross' showed the worst visual quality, whereas 'Penn A-4' and 'Crenshaw' the best quality. 'Putter', which was maintained a fair quality during the test period, was regarded as a good cultivar because of no significant variation in summer as compared to the other caltivars. 'Crenshaw',' L-93' and 'Penn A-4' were greater in chlorophyll content and 'Penncross' lowest during the summer. Also, 'SR1020' had a low content of chlorophyll. 'Putter' greatly increased in chlorophyll content after fertilization. The highest shoot density($19.3/cm^2$) was found with 'L-93' in early August, followed by 'Crenshaw', 'Penn A-4', 'Putter', 'Dominant', and 'SR1020' in that order. However, 'Penncross' was lowest($15.7/cm^2$). As for a root length, 'L-93' was longest, being over an average 5.5cm. 'Penn A-4' and 'Putter' also showed good result in root growth. However, the root length considerably decreased with 'SR1020', 'Penncross' and 'Dominant' in summer. Brown patch was a serious disease for the most cultivars, except 'Penncross'. 'Dominant' had the most serious damage. 'Putter', 'L-93', 'Crenshaw', 'SR1020', and 'Penn A-4' were also greater in damage over the others. In regards of algae occurrence in summer, 'Penn A-4' had the least damage, while 'Dominant' the greatest. In conclusion, 'Crenshaw', 'Penn A-4' and 'L-93' were the best cultivars in terms of summer growth. Conversely, 'Penncross' was the poorest one. However, this study was conducted under the conditions of one-year old green. Accordingly, in-depth experiment should be done over several years to elucidate the characteristics of growth for the wide range of creeping bentgrass cultivars during the summer.

The Aesthetic Qualities Featured in Vivienne Westwood's Works (비비안 웨스트우드(Vivienne Westwood)의 작품세계와 미적특성)

  • 염혜정
    • Journal of the Korean Society of Costume
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    • v.37
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    • pp.71-88
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    • 1998
  • This study will analyze the aesthetic qual-ities revealed in the work of Vivienne Wes-twood in order to gain an understanding of the development process and uniqueness of modern avant-garde fashion. Westwood gained worldwide recognition in the 1970s as the Punk movement emerged in London. Although her works have often been described as decadent and anti-establishment, her anarchic view of fashion has had a considerable influence on other designers, both in England and around the world. Vivienne Westwood's works can be divided into three periods. In the first period(1971∼78). Westwood design demonstrated elements which were variations of the subcultural Punk style. The noteworthy designs of this period included ripped T-shirts, bondage clothes, and fetishist accoutrements. In the second period(1979∼83), her designs expressed elements from ethnic and primitive tribal societies through the 'Pirate', 'Savages', 'Buffalo Girls', 'Witches' collections, which inspired New Romanticism movement. In the third period (1985∼ ), through works such as 'Mini-Crini'collection, her works identified elements from the old west and used materials such as crinoline and Harris tweed and contemporized them by rearranging the innovative technique. In the end the news synthesis helped formulate new ideas. The aesthetic qualities in Vivienne Wes-twood's works can bed identified with the following themes : Punkature, Erotic Intelligent-sia, Anarchic Collage. First, within Punkature, Westwood's ideas are at the forefront as her impact on the cut of clothes and creative detailing have been considerable. Also, while her ideas can be extreme, her clothes are wear-able, resulting in the synthesis of Punk and couture. Second, as Erotic Intelligentsia, Vivienne Westwood does not present sexuality as a straight forward attribute that fashion so often tends to do, but instead as a matter for inquiry, exploration and debate. She asserts that sexuality is always an interplay between the polarities of masculine and feminine, of dress and undress. Third, as Anarchic Collage, she has taken, juxtaposed, and transformed objects and symbols from dominant culture, like every modern subversive movement from Dada to Punk. She has continued this form of anarchic collage, mixing styles from various times and places, taking them out of their traditional context. From thiss viewpoint, Vivienne Westwood's works can be considered to be made up of past themes merged with is contemporary. The usage of contrasting elements such as Punk and couture to communicate her ideas visually or technically.

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KIC 6220497: A New Algol-type Eclipsing Binary with δ Sct Pulsations

  • Lee, Jae Woo
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.41.1-41.1
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    • 2016
  • We present the physical properties of KIC 6220497 exhibiting multiperiodic pulsations from the Kepler photometry. The light curve synthesis represents that the eclipsing system is a semi-detached Algol with a mass ratio of q=0.243, an orbital inclination of i=77.3 deg, and a temperature difference of ${\Delta}T=3,372K$, in which the detached primary component fills its Roche lobe by ~87% and is about 1.6 times larger than the lobe-filling secondary. To detect reliable pulsation frequencies, we analyzed separately the Kepler light curve at the interval of an orbital period. Multiple frequency analyses of the eclipse-subtracted light residuals reveal 32 frequencies in the range of $0.75-20.22d^{-1}$ with semi-amplitudes between 0.27 and 4.55 mmag. Among these, four frequencies ($f_1$, $f_2$, $f_5$, $f_7$) may be attributed to pulsation modes, while the other frequencies can be harmonic and combination terms. The pulsation constants of 0.16-0.33 d and the period ratios of $P_{pul}/P_{orb}=0.042-0.089$ indicate that the primary component is a ${\delta}$ Sct pulsating star in p modes and, thus, KIC 6220497 is an oscillating eclipsing Algol (oEA) star. The dominant pulsation period of about 0.1174 d is considerably longer than the values given by the empirical relations between the pulsational and orbital periods. The surface gravity of log $g_1=3.78$ is significantly smaller than those of the other oEA stars with similar orbital periods. The pulsation period and the surface gravity of the pulsating primary demonstrate that KIC 6220497 would be the more evolved EB, compared with normal oEA stars.

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Field observation of sediment suspension in the surf zone (쇄파대의 저질부유에 관한 현지관측)

  • 신승호;율산서소
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2003.05a
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    • pp.141-146
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    • 2003
  • Time seres of suspended sediment concentration, surface elevation and velocity were measured and analysed to investigate the role of waves and the predominance of infra-gravity wave component for sediment suspension phenomena in the surf zone. For the investigation in detail, we adopted the cross spectral analysis method between sediment concentration and the characteristic values of wave, and ensemble average analysis method about long-period wave component, which is dominant to sediment suspension in the measurement point. The obtained results are summarized as follows: 1) The relationship between sediment concentration and the characteristic values of wave is stronger for the long-period standing wave components(about 60s and 30s) than the long wave components(about 100s), which have the most energetic power, 2) and also, it is cleared that sediment concentration is increased in the case of the phase, the velocity components of the first mode long-period standing wave(60sec) were accelerated toward on-shore direction, that is, the water surface in offshore side is higher than on-shore side.

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A Study on the Erosion and Sedimentation Traces According to the Sea Level Changes Since the Medieval Warm Period in the Hwaseong Coast (화성 연안의 중세온난기 이후 해수면 변동에 연동된 침식·퇴적 흔적 연구)

  • Yang, Dong-Yoon;Han, Min;Kim, Jin Cheul;Park, Sujeong;Lim, Jaesoo
    • Journal of The Geomorphological Association of Korea
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    • v.26 no.2
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    • pp.39-54
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    • 2019
  • In this paper, based on evidence of coastal sediment, we show that erosion and sedimentation environments are very sensitive to sea level changes during the Medieval Warm Period (MWP) and the Little Ice Age (LIA). We identified four sedimentary units(4.57-3.07m), which formed in the Dark Age Cool Period (DACP), MWP and LIA were classified based on the lithostratigraphy, grain size distribution, magnetic susceptibility and geochemistry of a drilling core taken from the west coast of Hwaseong City. The unconformity surfaces as boundaries of the units were also identified by the lithostratigraphy shown on the drilling core. We propoese that sedimentation was dominant in the area during the periods of sea level rise, whereas erosion prevailed during the periods of sea level fall. Particularly, extreme events, such as floods and typhoons are believed to have accelerated these processes, and we found the associated evidence in sediments of two units. This study provides an example of estimating the relative sea level variation using coastal sediments and may be useful for studying past sea level changes around the Korean Peninsula.

Roles of Wind Stress Variations in the Western North Pacific on the Decadal Change of ENSO (ENSO 십년 변동에 미치는 북서태평양 지역에서의 바람 응력 변동의 역할)

  • Lee, Yoon-Kyoung;Moon, Byung-Kwon;Kwon, Min-Ho;Jhun, Jong-Ghap
    • Journal of the Korean earth science society
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    • v.27 no.6
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    • pp.687-694
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    • 2006
  • This paper investigated the effects of wind stress forcing in the western North Pacific on ENSO decadal change before and after the late 1970s. The SVD analysis of SODA data shows that a positive wind stress curl is dominant in the western North Pacific at the ENSO mature phase, which leads to the ENSO phase change by discharge/recharge heat contents in the equatorial Pacific. Before the late 1970s, the wind stress curl in the western North Pacific was strong. This strong wind forcing that is associated with the fast discharge of heat contents in the equator led to the short period and the weak intensity of ENSO occurred during the 1960-1970. On the other hand, after the late 1970s the relatively weak wind stress curl was accompanied with the long period and the strong intensity of ENSO. The simple coupled model experiments also confirm that the amplitude and dominant period of ENSO decrease when the wind stress curl in the western North Pacific projects more strongly into the ocean at the TNSO mature phase. Our results support that the changes in the behavior of ENSO after the late 1970s are associated with the wind stress variation in the western North Pacific.

Distribution Patterns of Macrobenthos during Recent Summer Seasons at the Bongam Sand Tidal Flat of Masan Bay, Korea (마산만 봉암갯벌에 서식하는 대형저서동물의 하계 분포양상)

  • Seo, Jin-Young;Kim, Jeong-Hyun;Choi, Jin-Woo
    • Korean Journal of Environmental Biology
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    • v.36 no.4
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    • pp.626-637
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    • 2018
  • In this study, a series of survey were conducted to identify the distribution patterns of macrobenthos at the Bongam sand tidal flat in Masan Bay. We collected macrobenthos at 9 sampling sites twice in June and September of every year from 2012 to 2017 using a box core sampler (collecting area, $0.025m^2$). There was a total of 50 species with a community density of $6,388ind.m^{-2}$ and a biomass of $313.9g\;wet\;m^{-2}$ during the study period. Polychaetes had the highest number of species and density among the macrofauna, but the mollusks had the largest biomass. The number of species ranged from 10 to 25 during study period but increased to over 20 species in 2014. The density which ranged from $1,508ind.m^{-2}$ to $12,008ind.m^{-2}$ rapidly increased in 2015. The dominant species were all polychaetes such as Heteromastus filiformis, Prionospio japonicus, Hediste diadroma, and Neanthes succinea. The mean diversity index ranged from 1.2 to 1.9, richness index from 1.2 to 2.4, and evenness index from 0.5 to 0.9. From the cluster analysis results, there was a spatial difference in the similarity of faunal composition of macrobenthos and this pattern was maintained throughout the study period, that is, the temporal similarities were higher than the spatial similarities. There was a change in community composition from June 2014 to June 2015 in most of the sampling sites. During this time, the dominant species also changed from H. filiformis and N. succinea to H. filiformis and H. diadroma. The density of opportunistic species such as Capitella capitata and Polydora ligni decreased compared to the early 2000s while the population of H. diadroma increased from 2015. There was little ecological information on H. diadroma such as when and where this species occurred.

STATISTICAL STUDY ON HABITUAL METHODS Of TOILET TRAINING FOR INFANT AND TODDLER (한국 영.유아의 대소변 가리기 훈련습성에 관한 일 연구)

  • 최경자
    • Journal of Korean Academy of Nursing
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    • v.3 no.3
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    • pp.119-132
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    • 1973
  • This study observed on habitual methods of toilet training for infants and toddlers in Korea thru 300 mothers at four medical institutions Ewha Woman′s University Hospital, Ewha Maternal and Child Health Center, Severance Hospital and Seoul National University Hospital) with a design to analyze beginning time, duration of period, methods employed, motives, equipments used, special terminology used for the subject training. The main purpose of this study was to generalize the proper methods of toilet training, and also to contribute a better psychological education for the mother and child. The results obtained from this study were as follows; 1. Majority of (67.3%) observed were in the age category between 30 and 40 years, and dominant numbers (64.7%) were housewives with high level of education and from middle class family background. 2. In the most cases (85%), toilet training was carried out by mothers(including wives who had a job) while more than half of mothers (53.7%) maintained their important motive for the training was "due to having high regard for cleanliness" 3. As for the time of beginning toilet training: finding indicated that starting period was decided (70%) at inconsiderate desertion of each mother. whereas, only minority group (30%) represents the cases where mother started the training when they consider tile child was physically and psychologically randy. Also greater number (77.7%) started bladder training prior to that of bowel. 4. It is noticeable that in course of training a large number of mothers (48.3%) applied strict training method when the child proper talenting, and the more rigid and strict in tile training. the more malformation of personality of the infant and toddler were seen after the training period (P<0.01). 5. Over the half of the total cases denoted (bowel 54.3%, bladder 67.7%) starting period before one year and in most cases (bowel 79.3%, bladder 729)the training was accomplished within 12 month, and therefore it was noted that earlier start(before 1 year) shortened the training period (with 12 month) . There was no significant difference between male and female infants in both starting period and duration of period in bladder training, however, in bowel training there was a tendency that female started earlier(7-12 months needed, 51.4%) than tile male (13-18 months needed, largest number 41.4%), and also in cases of female the period for needed for training were shorter than the cases of male. 6. Many a number (bowel 50.3%, bladder 97.7%) employed the method of continuous talenting at regular interval in accordance with that of child′s habit formed before training. Equipment used were various kinds, however, pieces of paper for male (45.5%) and piss pot or bedpost (42.3%) for female were common, on the other hand, "Eung-ga" for defecation (52.3%) and "Shii" for the urination (95.3%) were most standard expression that used during the training period.

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Long-Period Wave Oscillations in Sokcho Harbor and Cheongcho Lagoon (1. Field Measurements and Data Analyses) (속초항과 청초호의 부진동 특성 (1. 현장관측과 자료 분석))

  • 정원무;박우선;김규한;채장원;김지희
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.1
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    • pp.51-64
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    • 2002
  • To investigate long-period wave responses in Sokcho Harbor and Cheongcho lagoon, field measurements were made for long-and short-period waves and current velocities using a Directional Waverider, a ultrasonic-type wave gauge, four pressure-type wave gauges, and a current meter. From the data analysis, it was found that the Helmholtz resonant periods of Sokcho Harbor and Cheongcho lagoon are about 13.6 and 54.5 minutes, respectively, and the dominant period of wave induced current in the passage between Sokcho Harbor and Cheongcho lagoon is about 55.2 minutes which depends on Helmholtz resonant condition of the Cheongcho lagoon. It was also found that the energy level of the far-infra-gravity waves during storm conditions is very high compared with that during calm sea conditions. To investigate relationships between far-infra-gravity waves and short-period waves at offshore station, regression analyses were carried out especially for 1) heights, 2) periods, 3) direction and height, 4) height and period between short-and far-infra-gravity waves, respectively. The results showed that the long-period wave height is highly correlated with the short-period wave height. However, no special trend was found for the other relations. In the future far-infra-gravity wave heights on return period around Sokcho Harbor region can be suggested by using extreme value analyses of long term measured data.