• Title/Summary/Keyword: 원판

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발전기의 전기보호

  • 전민호
    • Electric Engineers Magazine
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    • v.198 no.2
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    • pp.32-37
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    • 1999
  • 발전기도 여타 주요 전기설비와 마찬가지로 다중 보호되도록 하여 안전을 도모하고 있으며 보호방법에 있어서는 유도원판형 등 아날로그 방식에서 디지털 방식으로 발전, 변경되고 있지만 보호의 종류, 보호 목적 등에 있어서는 종전과 다를 바가 없다.

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A Study on the Thrust Force of a Narrowly Spaced Disk Valve (좁은 틈새 원판 밸브의 추력에 관한 연구)

  • Jeong, Hyo-Min;Kim, Si-Young
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.23 no.1
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    • pp.30-38
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    • 1987
  • One of the important characteristics of a disk valve is the thrust force. This thrust force has close relationship to the clearance between valve and valve seat in the disk valve. When the clearance is very small, it is very important to analyze the thrust force. This paper deals with the variation of the thrust force by comparing the experimental ed results and theoretical results in accordance with d the valve clearance. In case of the theoretical problems, the pressure gradient of the radial flow in a narrowly spaced disks was calculated by Sui Lin and Pai-Mow Lee already. Therefore, the thrust force of the disk valve was computed by utilizing this pressure gradient in the radial flow. In the experiment, the hydraulic oil which has high viscosity was used. Making the comparative study of the calculated results and the experimental results, the characteristics of the thrust force in the disk valve were investigated. The results obtained are as follows: 1. When the disk valve clearance was comparatively small, the experimental values had fairly good agreement with the calculated values independently of inlet pressure and valve size. 2. When the disk valve size was constant in the wide range of the disk valve clearance, the lower the inlet pressure was, the better the agreement between the experimental values and the calculated values was. 3. In case of the small clearance, the thrust force was depended on the outer diameter of the disk valve. In opposite case the thrust force was constant as the disk valve size varied.

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A Study on Heaping of Granules (알갱이 군의 무더기 현상에 관한 연구)

  • Han, Ji Heum;Han, Won Heum;Lee, Kwang-Hee
    • Journal of Adhesion and Interface
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    • v.14 no.4
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    • pp.183-191
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    • 2013
  • In order to elucidate the granular heaping phenomenon, the movement behaviors of 3 different types of granule (millet, sand and thin foil disc) have been investigated by applying the vertical or the rotational vibration to each of the 3 vessels, respectively containing one of the 3 types of granule. In case of vertical vibrations, all of them showed the heaping phenomenon like Gerner's simulation, and that in the order of the millet, sand and thin foil disc, regardlessly of weight. Especially, a heaping of disc granules was proven to be relatively delayed, and that with several small complex clutters. For rotational vibration, the central area of vessel turned out to rise up due to the repulsive force by vessel wall as well as the collision between elastic granules, right after the turning point of vibration. Even spiral pattern was made when the rotational vibration amplitude got higher. From these facts, one can see that the heaping be characterized by the inclusion of attractive granules as well as the vibrational type applied to granule vessel.

Effects of Drying Temperature and Acetylation on The Retention of Polyethylene Glycol in Red Pine Wood Disks (건조온도와 아세틸화처리가 소나무 원판의 Polyethylene Glycol 잔류량에 미치는 효과)

  • Lee, Won-Hee;Hong, Seung-Hyun;Kang, Ho-Yang
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.6
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    • pp.784-791
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    • 2015
  • Polyethylene glycol (PEG) impregnation prevents a red pine disk from cross-sectional checking during drying. Percentage of PEG Retention (PPR) was measured by the experimental methods of aceton extraction and moisture conditioning in a saturated salt solution and the effect of acetylation on PEG impregnated wood was investigated. PPRs of the kiln-dried specimens were much higher than those of the air-dried by at least four times and within the kiln-dried specimens those of the sapwood were higher that those of the heartwood by two times. These results were confirmed by the moisture conditioning experiment. Acetylation increased the weights of the kiln-dried specimens much less than those of the air-dried. It was revealed that acetic anhydride solution eluted PEG-1000 in the specimens. It is concluded that kiln-drying is more effective than air-drying for the increase of PPR and that acetylation eliminates the difference between the kiln- and air-dried specimens.

Analysis of Axial Capacity and Constructability of Helical Pile with Inner Cone Penetration (내부 콘 항타를 적용한 헬리컬 파일의 지지력 및 시공성 분석)

  • Lee, Jun-Ho;Lee, Kicheol;Kim, Dongwook
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.4
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    • pp.1-11
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    • 2017
  • In this study, 1/6 small-scale model tests of helical piles were conducted to evaluate their installation time and ultimate capacities. Model sand layers were constructed using sand pluviating method to produce uniform soil relative density. For installation of different helical piles varying locations (vertical center-to-center spacings of 50 mm and 150 mm) of helix plates, two different rotation speeds of 15 rpm and 30 rpm were implemented. Cone penetration equipment was installed within the hallow section of the helical pile to increase ultimate capacity of helical pile and to evaluate soil properties of plugged soils and soils below pile tip after installation of the piles. Based on the test results, the most fasted installation was possible under the condition of "rotation speed of 30 rpm and center-to-center spacing of 50 mm", and the highest ultimate capacity was mobilized under the condition of "rotation speed of 30 rpm and center-to-center spacing of 150 mm with cone penetration implementation."

Effect of Configuration of Shaft and Helix Plate on Bearing Capacity of Moderate-size Helical Pile : II. Bearing Capacity Prediction (중소구경 헬리컬 파일의 축과 원판의 형상이 지지력에 미치는 영향 평가 : II. 이론식과 토크에 의한 지지력 예측 비교)

  • Lee, Jongwon;Lee, Dongseop;Na, Kyunguk;Choi, Hangseok
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.2
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    • pp.41-47
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    • 2014
  • Various prediction methods for the bearing capacity of helical piles have been introduced with consideration of both the steel shaft and the helix plates attached to the shaft. In this paper, three representative methods, that is, individual bearing method, cylindrical shear method, and torque correlation method are discussed and compared to each other. The prediction methods were verified by comparing with a series of loading test results performed on moderate-size helical piles from the companion paper. As a result, the measured bearing capacity is greater than the bearing capacity predicted by the cylindrical shear method, but smaller than that of the individual bearing method. In addition, the bearing capacity predicted by the torque correlation method is in good agreement with the measured bearing capacity.

The Review for Various Mold Fabrication toward Economical Imprint Lithography (미세패턴 전사기법을 위한 다양한 몰드 제작법 소개)

  • Kim, Joo-Hee;Kim, Youn-Sang
    • Journal of the Korean Vacuum Society
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    • v.19 no.2
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    • pp.96-104
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    • 2010
  • We suggest here a cost-effective replica fabrication method for transparent and hard molds for imprinting lithography such as NIL and S-FIL. The process starts with the use of a replica hard mold from a master, using a polymer copy as a carrier. The polymer copy as a carrier was treated by soluble process for forming anti-adhesion layer. Duplicated hard molds can eliminate direct contact between a hard master and a patterned polymer on a substrate and the generated contamination of a master during the imprinting process. The replica hard mold exhibits the glass-like properties introduced here, such as transparency and hardness, make it appropriate for nanoimprint lithography and step-and-flash imprint lithography.