• Title/Summary/Keyword: 노치타입

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Effect of Compressive Strength and Curing Condition on the Direct Tensile Strength Properties of Ultra High Performance Concrete (압축강도 및 양생조건에 따른 초고성능 콘크리트의 직접인장강도 특성)

  • Park, Ji Woong;Lee, Gun Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.17 no.2
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    • pp.175-181
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    • 2017
  • The purpose of this study is evaluating the characteristics of tensile strength of UHPC and examining tensile performance of notched specimens by direct tensile test. For test variables, 120, 150, and 180MPa of target design standard strength were aimed at. With general water curing and $90^{\circ}C$ high temperature steam as curing conditions, the properties were reviewed. Overall, it was represented that the specimens of notch-type direct tensile strength concrete was effective in inducing central cracks compared with existing direct tension specimens. Through this, it was judged that data construction with high reliability was possible. Above all, in a graph of direct tensile strength and strain, in the case of steam curing at high temperature, there was great difference of initial tensile strength compared with water curing. As passing of ages, an aspect that the difference gradually decreased was shown. Maximum tensile strength was found to increase steadily with increasing age for all target design strengths in water curing, in the case of steam curing, the tendency to increase significantly due to the initial strength development effect at 7 days of age. The initial crack strength increases with age in case of underwater curing, in the case of steam curing, it was higher than that of water curing in 7 days, while the strength of 28 days was lowered. In this part, it is considered necessary to examine the arrangement condition of the steel fiber.

Characteristic Analysis for the Reduction Detent Force of Double-sided Slotted Type Permanent Magnet Linear Generator for Wave Energy Conversion (파력에너지 변환용 양측식 슬롯티드 타입 선형 발전기의 디텐트력 저감을 위한 특성해석)

  • Seo, Sung-Won;Choi, Jang-Young;Koo, Min-Mo;Park, Hyung-Il;Hong, Keyyong;Kim, Kyong-Hwan
    • Journal of the Korean Magnetics Society
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    • v.26 no.1
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    • pp.31-37
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    • 2016
  • This study considered the reduction of the detent force of a permanent magnet linear synchronous generator (PMLSG). The PMLSG has a relatively large magnetic air gap. Thus, a slotted type of stator structure is generally employed. Furthermore, the detent force, which is caused by energy imbalances owing to the interaction between tooth-slot structures and the permanent magnets (PMs), must be minimized for start-up operation. Therefore, in this paper, the methods of auxiliary teeth and a notch in the teeth are applied to reduce the detent force.

UWB Antenna with Triple Band-Notched Characteristics Using the Spiral Resonator and the CSRR (스파이럴 공진기와 CSRR을 이용한 삼중 대역 저지 특성을 갖는 UWB 안테나)

  • Kim, Jang-Yeol;Lee, Seung-Woo;Kim, Nam;Lee, Sang-Min;Oh, Byoung-Cheol
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.11
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    • pp.1078-1091
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    • 2011
  • In this paper, a triple band-notched UWB antennas using a spiral resonator and a complementary split ring resonator is proposed as two types. The band-rejection characteristic of the designed antenna is analyzed through the structure and equivalent circuit model of spiral resonator and CSRR. The measured results of first type antenna show that a VSWR less than 2 was satisfied with a resonant frequency in the range of 1.16~12 GHz and it can be obtained the band-stop performance at 3.3~3.85 GHz, 5.15~6.1 GHz, and 8.025~8.5 GHz. The measured results of second type antenna show that a VSWR less than 2 was satisfied with this antenna works from 1.79 to 12 GHz and it can be achieved the band-notched performance at 3.3~3.88 GHz, 5.12~5.94 GHz, and 8.025~8.51 GHz. Through the measured results, the designed antenna was satisfied UWB band except for triple notched bands.

Durability Design of Composite Piston in Marine Diesel Engines (박용 디젤엔진용 분리형 피스톤의 내구설계)

  • Son, Jung-Ho;Ha, Man-Yeong;Ahn, Sung-Chan;Choi, Seong-Wook
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.5
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    • pp.651-657
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    • 2010
  • A composite piston with a crown made of steel and a skirt made of NCI is used in a marine diesel engine, which has a maximum firing pressure of over 180 bar and a high thermal load. In the fatigue design of the composite piston, the fatigue is influenced by factors such as the load type, surface roughness, and temperature; further, the distribution ratio of the firing force from the crown to the skirt is important for optimizing the design of the crown and skirt. In this study, the stress gradient method was used to consider the effect of the load type. The temperature field on the piston was predicted by cocktail-shaking cooling analysis, and influence of high temperature on fatigue strength was investigated. The load transfer ratio and contact pressure were optimized by design of the surface shape and accurate tolerance analysis. Finally, the cooling performance and durability design of the composite piston were verified by performing a long-term prototype test.