• Title/Summary/Keyword: Daedong

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Organ Fossils of Neocalamites carrerei from the Amisan Formation of the Nampo Group, Korea (남포층군 아미산층에서 산출된 Neocalamites carrerei의 기관화석)

  • Kim, Jong-Heon;Roh, Heon-Sun
    • Journal of the Korean earth science society
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    • v.29 no.6
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    • pp.466-473
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    • 2008
  • This study deals with the morphological characteristics and structure of organ fossils of Neocalamites carrerei such as rhizomes, aerial leafy stems, and cones collected in situ from the Amisan Formation of Nampo Group. Judging from the size of some extant Equisetum and paleoclimate of Daedong flora, it is considered that the size of Neocalamites carrerei was probably very large. The cone of Neocalamites takahashii (Kon'no) is closely associated with the leaves of Neocalamites carrerei. It indicates that two organ fossils mentioned above probably belong to the same species. Comparing with very abundant occurrence of aerial leafy stems and rhizomes in the Amisan Formation, cones are very rare. This fact implies that Neocalamites reproduce not only by spore reproduction, but also by asexual reproduction. Neocalamites largely differ in the leaf form and size from Equisetum.

Sang-Seol Lee's manuscript on modern physics in the late 19th century Korea (수학자 보재 이상설(李相卨)의 근대자연과학 수용 - 『백승호초(百勝胡艸)』를 중심으로)

  • Lee, Sang-Gu;Park, Chong-Yun;Kim, Chae Sik;Lee, Jae Hwa
    • Communications of Mathematical Education
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    • v.27 no.4
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    • pp.487-498
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    • 2013
  • Sang-Seol Lee(1870-1917) wrote a manuscript BaekSeungHoCho(百勝胡艸) in the late 19th century. BaekSeungHoCho was transcribed in classical Chinese from the 1879 Japanese book Physics(物理學) by Teizo Ihimori (1851-1916). Sang-Seol Lee, a famous independence activist, is also called Father of the Modern Mathematics Education of Korea, because of his early contribution to the modern mathematics education in the 19th century. In this paper, we introduce contents of his manuscript BaekSeungHoCho for the first time and discuss the significance of this book. Also, we show his contribution on the introduction to modern physics in the late 19th century Korea.

Analysis of Quantitative Research Published by Korean Journal of Adult Nursing (1989~2011) (성인간호학회지(1989~2011)에 게재된 양적 연구의 동향 분석)

  • Kim, Young-Kyeong;Hwang, Sun-Kyung;Kim, In-Ja;Kim, Ju-Sung;Oh, Hee-Young;Lee, Jong-Kyung;Jung, Eun-Sook;Choi, Gui-Yun;Choi, Ja-Yun
    • Korean Journal of Adult Nursing
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    • v.24 no.1
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    • pp.85-97
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    • 2012
  • Purpose: The aims of this study were to examine the trend of quantitative study in Korean Journal of Adult Nursing published between 1989-2011 and to provide future directions for nursing research in adult health nursing. Methods: A total of 883 published articles were reviewed, and main subject and the methodology were analyzed using descriptive statistics. Results: The most frequently cited keywords were elderly, quality of life, depression, knowledge, stress and anxiety. The survey study was the most popular research design (67.6%) followed by experimental (26.5%), and methodological study (5.5%) design. Over 80% of studies with translated or developed instruments reported reliability for psychometric analysis, while only 18% of the studies reported validity of the instruments they used. In the periods of 2006~2011, significantly more studies utilized experimental design, obtained IRB approval and written consent, and included power analysis for sample size calculation. In recent experimental study, educational program and complimentary therapy were the two most frequently used interventions. Conclusion: Through the analysis of nursing studies published in Korean Journal of Adult Nursing, we found the number of experimental studies has increased and methodological rigor has improved in recent years.

The Effect of Mental Health on the Health-Related Quality of Life among the Elderly in Busan (부산시 노인의 정신건강이 건강관련 삶의 질에 미치는 영향)

  • Kim, Mi-Jin;Song, Gab-Sun
    • Journal of Digital Convergence
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    • v.18 no.5
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    • pp.269-277
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    • 2020
  • The purpose of this study is to identify the factors affecting Health-related Quality of Life of Elderly in Busan. Then this study would like to present basic data that can be used in research into specific measures to improve Health-related Quality of Life of Elderly in Busan. The subjects of this study were a total of 3452 elders aged 65 or higher in 2016 Community Health Survey. Data were analyzed using descriptive statistics, Mann-Whitney U test, Kruskal-Wallis test and multiple linear. The results showed that subjective health status perception, depression, stress, education level, the national basic livelihood security, sleep duration, BMI, Marital status, hypertension were found to be the influencing factors of subjective happiness and explained 28.8% of Health-related Quality of Life.

Stratigraphy and Tectonics of Okcheon System in the Area between Chungju and Munkyeong (충주문경간(忠州聞慶間)의 옥천계(沃川系)의 층서(層序)와 구조(構造))

  • Kim, Oku Joon
    • Economic and Environmental Geology
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    • v.1 no.1
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    • pp.35-46
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    • 1968
  • Some of geologists in Korea recently postlated that Okchon system previously known to be precambrian age was the metamorphosed sediments of post-Chosen (Ordovician and pre-Kyeongsang (late Jurassic to Cretaceous) periods, or even definitely of Triassic period simply on the basis of the fact that Okcheon system overlies the Great Limestone series of Chosen system of Camber-ordovician age, and of other few assumptions of minor importance. As a result of such correlation, thick series of metasediments and Okcheon system of unknown age were established in this particular region and vaguely correlated to Paleozoic and Mesozoic sediments. Recent study done by the author reveled that: 1) only the upper Okcheon bed of S. Nakamura was true Okcheon system, and the middle and lower Okcheon beds were excluded, because they were correlated to Cambrian and Permian sediments resfectively, 2) Sangnaeri, Seochangri, and rengam formations of unknown age, and Baekhwasan, Jobong, and Ihwaryeong formations of Okcheon system of also unknown age were the metamorphosed Yangdeok system of Cambrian age, all of these formations were differentiated by the previous workers and were equivalent to the middle Okcheon system of S. Nakamure, and. 3) These metamorphosed Yangdeok system overlaid apparently the Great Limestone series in forms of overthrust and klippe which were produced by the orogeny took place during post-Daedong and pre-Kyeongsang period (probably middle to the Jurassic). The Sobaeksan Range, folded mountain Chains was also formed by this orogeny. Thus, Okcheon system newly defined by the author is precambrain age and consists in ascending order of Kemyenogsan, Hyangsan dolomite, and Daehangsan quartzite formation which were previously classified into metasediments of unknown age, and Munjuri, and Hwangkanri, formations which were differentiated into Okcheon system unknown age by the previous workers, but are of reversed sequence. Myeongori and Bukrori formations of Okcheon System are regard by the author as part of Hwangkanri formation. Few other assumption of minor important taken by the previous workers as their positive evidences are carefully explained that they were misinterpreted.

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Standing Crop Distribution of Aquatic Plants in the West Nakdong River and Riparian Wetlands in the Nakdong River (서낙동강 본류 및 낙동강 둔치 습지의 수생식물 생물량 분포)

  • Kim, Gu-Yeon;Kim, Ji Yoon
    • Korean Journal of Ecology and Environment
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    • v.47 no.1
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    • pp.62-69
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    • 2014
  • Standing crop distribution of aquatic plants in the West Nakdong River and riparian wetlands in the Nakdong River were surveyed in May, July and September, 2010. Total 25 aquatic macrophyte species (submerged: 9, leaf-floating: 3, free-floating: 5, emergent: 8) were observed during the survey periods. Distribution area of aquatic plants and proportion of submerged communities were highest in Garakchi-deung ($212,032m^2$, 72.7%). The distribution area of aquatic plants was highest in Phragmites australis community ($421,584m^2$), followed by Hydrilla verticillata-Vallisneria natans community ($181,511m^2$), Potamogeton wrightii-Vallisneria natans community ($61,604m^2$), and Hydrocharis dubia community ($49,709m^2$). Garakch-ideung (212,032 kg) also had the highest aquatic plant production, followed by Suanchi-deung (15,546 kg), Daedong (5,813 kg), Dunchi-do (3,963 kg), Maekdo (1,463 kg), Yeommak (571 kg), Jungsa-do (530 kg), and Shinan (300 kg). Average standing crop of the study area were $147.8{\pm}20.8g\;DW{\cdot}m^{-2}$ in 1988, $96.1{\pm}20.0g\;DW{\cdot}m^{-2}$ in 2000, and $172.6{\pm}76.1g\;DW{\cdot}m^{-2}$ in 2010. For a sustainable management of river habitat and food source, aquatic plant should concurrently be surveyed with river environmental variables (i.e. sediment, nutrient, flow).

Grain Refinement and Mechanical Properties of AM60 Mg Alloy by $CaCN_2$ Addition (Ca$CN_2$ 첨가에 의한 AM60 마그네슘 합금의 결정립 미세화 및 기계적 성질)

  • Eom, Jeong-Pil;Jeong, Seong-Kyu;Lim, Su-Geun;Shin, Hee-Taek;Jeong, Deuk-Soo
    • Journal of Korea Foundry Society
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    • v.18 no.4
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    • pp.383-388
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    • 1998
  • Effects of $CaCN_2$ addition on the grain refinement in the AM60 magnesium ingots were investigated. The effects of the $CaCN_2$ are estimated with different inoculation temperatures, inoculation contents, and holding time to find out the optimum condition. AM60 alloy was melted in the low carbon steel crucible by cylindrical electric furnace under an argon atmosphere. The melting and casting apparatus is specially designed for magnesium alloys. The grain size of AM60 magnesium alloy decreased significantly with an increase in $CaCN_2$ content and, at 0.8 wt% $CaCN_2$ or more, grain size becomes constant at about $85 {\mu}m$. The optimum condition was obtained in the 0.8 wt% $CaCN_2$ for holding molten metal of 30 min. at the temperature of $710^{\circ}C$. The tensile properties of AM60 magnesium alloys were improved due to grain refinement by addition of $CaCN_2$. In the optimum condition, the yield strength, tensile strength and elongation were ${\sigma}_{0.2}=107 MPa$, ${\sigma}_{T.S}=234 MPa$ and e=14.2%. The variation of stress with strain obeyed the relationship of the ${\sigma}=K{\varepsilon}^n$. The strain-hardening exponent, n and strength coefficient, K obtained in the 0.8 wt% $CaCN_2$ added AM 60 magnesium alloy were n=0.21 and K=390 MPa.

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Low-Load/Low-Eccentricity Performance Improvement Designs for Hydro Power Application of Cylindrical Turbine Guide Bearings - Introduction of Pad Leading-Edge Tapers (수력 원통형 터빈 가이드 베어링의 저부하/저편심 성능향상 설계 - 패드 선단 테이퍼의 도입)

  • Lee, An Sung;Jang, Sun-Yong
    • Tribology and Lubricants
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    • v.33 no.2
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    • pp.65-70
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    • 2017
  • In vertical hydro/hydraulic power turbine-generator applications, traditionally, cylindrical turbine guide bearings (TGBs) are widely used to provide turbine runner shafts with smooth rotation guides and supports. All existing cylindrical TGBs with simple plain pads have drawbacks such as having no pressure generation and film stiffness at the no-load condition and in addition, at the low-load/low-eccentricity condition, having very low film stiffness values and lacking design credibility in the stiffness values themselves. In this paper, in order to fundamentally improve the low-load/low-eccentricity performance of conventional cylindrical TGBs and thus enhance their design-application availability and usefulness, we propose to introduce a rotation-directional leading-edge taper to each partitioned pad, i.e., a pad leading-edge taper. We perform a design analysis of lubrication performance on $4-Pad{\times}4-Row$ cylindrical TGBs to verify an engineering/technical usefulness of the proposed pad leading-edge taper. Analysis results show that by introducing the leading-edge taper to each pad of the cylindrical TGB one can expect a constant high average direct stiffness with a high degree of design credibility, regardless of load value, even at the low-load/low-eccentricity condition and also control the average direct stiffness value by exploring the taper height as a design parameter. Therefore, we conclude that the proposed pad leading-edge tapers are greatly effective in more accurately predicting and controlling rotordynamic characteristics of vertical hydro-power turbine-generator rotor-bearing systems to which cylindrical TGBs are applied.

A Case Study of Tunnel Stability due to the Shallow Shaft and Change Penetrating Location (터널 갱구부 저토피 및 관통부 변경에 따른 안정성 검토 사례 연구)

  • Lee, Saik;Choi, Youngchul;Jung, Wooyong;Kim, Kookhan;Kim, Dongin
    • Tunnel and Underground Space
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    • v.23 no.2
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    • pp.87-98
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    • 2013
  • Around 70% of Korea is mountainous, an increase in tunnel construction. It's due to the growing interest of the public for the environment and land required for the road construction is very scarce. During construction of 'Daedong 1 tunnel' in the expressway expansion project between Naengjeong and Busan, there are shallow shaft due to this tunnel located in the valley and the shafts are separated, and penetrating location change was inevitable for construction was delayed because of complaint. So, we change the position of the penetrating by applying multi-channel TSP, and conducted a stability analysis. The analysis results showed that there is no problem on the stability of the tunnel. To secure the construction of additional stability, We installed instrument, performed mechanical excavation, added reinforcement at shallow shaft and conducted bench cut.

Performance Improvement of Cylindrical Turbine Guide Bearings with Pad Leading-Edge Tapers for Vertical Hydro-Power Application: Effects of Taper Angle and Length (패드 선단 테이퍼를 갖는 수력 수직 원통형 터빈 가이드 베어링의 성능향상 - 테이퍼 각도와 길이의 영향)

  • Lee, An Sung;Jang, Sun-Yong;Park, Soo Man
    • Tribology and Lubricants
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    • v.34 no.1
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    • pp.16-22
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    • 2018
  • Cylindrical turbine guide bearings (TGBs) with simple plain pads have conventionally been used in vertical hydro-power turbine-generator applications in order to provide turbine runner shafts with smooth rotation guides and supports. To overcome low-load/low-eccentricity performance drawbacks, such as very low film stiffness and lack of design credibility in the stiffness values themselves, of conventional cylindrical TGBs, the introduction of a rotational-directional leading-edge taper to each partitioned pad, simply pad leading-edge taper, has been found to be very effective in enhancing their design-application availability and usefulness. In this study, we investigate the effects of taper angle and length for given taper heights in detail in order to systematically establish the effectiveness of design on the performance improvement of vertical hydro-power application cylindrical TGBs with pad leading-edge tapers. The analysis results with $4-Pad{\times}1-Row$ cylindrical TGBs show that the lubrication performance of the cylindrical TGBs is optimized with an approximate taper angle ratio of 0.8 and taper length ratio of 0.9. We conclude that the introduction of pad leading-edge tapers along with the optimization of taper designs can be very effective in improving the overall operation reliability of cylindrical TGBs and the rotordynamic characteristics of vertical hydro-power turbine-generator rotor-bearing systems as well, to which the TGBs are applied.