• Title/Summary/Keyword: DO-254

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Development of low power type sensor for the DO concentration measurement by clark electrode (Clark전극에 의한 DO 농도측정을 위한 절전형 센서개발에 관한 연구)

  • 이동희
    • Electrical & Electronic Materials
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    • v.8 no.3
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    • pp.254-260
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    • 1995
  • A method is described for the design and fabrication of the sensor interface circuits on the Clark electrodes for the dissolved oxygen(DO). The discussion includes a method for the +5 V single-supply driving for the sensor circuits, which has low power comsumption for the front-end electronics. DO probe under test is composed of the Clark electrode with silver anode, gold cathode and the electrolyte of half saturated KCI solution and the FEP teflon memtrance for the oxygen penetration. Typical polarograms for the DO probes by using this sensor circuit reveals high accuracy over 99% of the I to V conversion. Partial pressure of oxygen obtained from the polarograms are well suited to the results calculated. It is expected that the proposed sensor circuits can be utilized into the customized IC for the battery-driven small-size DO meters.

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Stem Rot of Euphorbia marginata Caused by Sclerotium rolfsii (Sclerotium rolfsii에 의한 설악초 흰비단병)

  • Kwon, Jin-Hyeuk;Kang, Dong-Wan;Kim, Min-Keun
    • The Korean Journal of Mycology
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    • v.39 no.3
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    • pp.254-255
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    • 2011
  • Stem rot symptoms of Euphorbia marginata were occurred in the herb exhibition field at Gyeongsangnam-do Agricultural Research and Extension Services in Korea. The typical symptom was started with watersoaking lesion on the stem then gradually rotted, wilted, and blighted, the severely infected plants were eventually died. The sclerotia of the pathogen were globoid in shape, 1~3mm in size and white to brown in color. The optimum temperature for mycelial growth and sclerotia formation on PDA was $30^{\circ}C$. The hyphal width was 4~9 ${\mu}m$, and the typical clamp connection structures were observed in the hyphae of the fungus grown on PDA. On the basis of mycological characteristics and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report of stem rot on E. marginata caused by S. rolfsii in Korea.

Education of Collaborative Product Data Management by Using Social Media in a Product Data Management System (소셜미디어와 PDM 시스템을 활용한 협업적 제품자료관리 교육)

  • Do, Namchul
    • Korean Journal of Computational Design and Engineering
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    • v.20 no.3
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    • pp.254-262
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    • 2015
  • This study proposes an approach to Product Data Management (PDM) education for collaborative product data management, which can support collaborative product development process. This approach introduces social media and a PDM system into a framework for PDM education supported by consistent product development process and product data model. It has been applied to two PDM classes and the result shows that the social media in PDM education can support not only experiences of the collaborative product data management but also interactive and informal communications among instructors and participants using integrated social media with product data during courses.

Radiographic Study of the Alveolar Bone Changes with Aging (증령에 따른 치고졸의 변화에 관한 방사선학적 연구(I))

  • 김영구
    • Journal of Oral Medicine and Pain
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    • v.8 no.1
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    • pp.77-82
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    • 1983
  • The author measured the degree of alveolar bone resorption around mandibular central incisors in Korean female(254). Mandibulr central incisors were selected from the females who do not have periodontal disease or malocclusion. The selected radiograms were enlarged in the $5"\times7"$ printing papers for the precise measuring. The obtained results were as follows : 1. The average alveolar bone resorption around mandibular central incisors in Korean women were 1.91mm in 3rd decade, 2, 16mm in 4th decade, 2.51mm in 5th deacade, 2.70mm in 6th decade, 2.94mm in older age group. 2. Alveolar bone resorption and age were in positive correlation; there is a tendency that the alveolar bone resorption increase with aging. 3. The regression equation is as follows. Y=13.57x + 7.06(r=0.60, n=254) (Y=estimated age, x=Length(C-E Junction alveolar crest)lar crest)

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Vibration Analysis of a Rotor considering Nonlinear Reaction of Hydrodynamic Bearing

  • Lee, Soo-Mok;Lim, Do-Hyeong;Bae, Jong-Gug;Yang, Bo-Suk
    • International Journal of Fluid Machinery and Systems
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    • v.2 no.3
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    • pp.254-259
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    • 2009
  • In this paper it was attempted to treat the hydrodynamic journal bearing as a time-based nonlinear reaction source in each step of rotor rotation in order to observe the bearing effect more realistically and accurately in stead of the conventional method of simple linearized stiffness and damping. Lubrication analysis based on finite element method is employed to calculate the hydrodynamic reaction of bearing and Newmark's method was used to calculate the rotor dynamics in the time domain. Simulation for an industrial electrical motor showed remarkable results with differences compared to those by the conventional method in the dynamic behavior of the rotor.