• Title, Summary, Keyword: 쇼트

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Cavitation Erosion Behavior in Seawater of Shot Peened Gray Cast Iron (쇼트피닝 처리된 회주철의 해수 내 캐비테이션 침식 손상 거동)

  • Park, Il-Cho;Kim, Seong-Jong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.111-111
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    • 2017
  • 쇼트피닝 기술은 크게 피로강도 향상을 위한 쇼트피닝(shot peening), 재료의 청정 및 도장 품질 향상을 위한 쇼트블라스트(shot blast) 그리고 쇼트피닝 시 판재의 변형되는 성질을 이용한 핀포밍(peen forming) 등으로 구분할 수 있다. 그 중 본 연구에서는 해양산업 분야에서 널리 사용되는 회주철의 효과적인 내구성 향상을 위해 쇼트피닝 기술을 적용하였다. 그러나 쇼트피닝 기술 적용에 있어서 가장 중요한 것은 제품의 균일성, 정확성, 신뢰성을 확보하기 위해 쇼트피닝 강도를 제어하는 여러 가지 변수들에 대하여 최적 상태를 유지하는 것이다. 따라서 회주철에 대한 최적 쇼트피닝 분사조건 규명작업은 반드시 쇼트피닝 가공 전에 수반되어야만 한다. 그 일환으로 실험은 쇼트피닝 분사시간과 분사압력을 변수로 하여 회주철 표면에 적용하였으며, 기계적 특성 평가를 통해 최적의 쇼트피닝 조건을 규명하고자 하였다. 쇼트피닝 분사조건에 따른 회주철의 내구성을 평가하기 위해 캐비테이션 실험을 실시하였으며, 경도 측정, 횡단면 관찰 및 표면의 3D 현미경 관찰 등을 통해 기계적 특성을 분석하였다. 캐비테이션 실험은 ASTM G32 규정에 의거하여 천연해수 내 $30^{\circ}C$에서 $50{\mu}m$의 진폭으로 실시하였다. 실험 후에는 주사전자현미경으로 손상표면을 관찰하였으며, 손상 정도를 비교하기 위해 무게 감소량을 계측하여 상호 비교/분석하였다.

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A Study on the Effect of Shot Peening on the Fatigue Life of Al 7075-T6 under Corrosion Environment (부식환경하에서 Al 7075-T6의 피로수명에 미치는 쇼트피닝의 효과에 관한 연구)

  • Cheong, Seong-Kyun;Nam, Ji-Hun;Kou, Dae-Lim;Ro, Seung-Nam
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.2
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    • pp.60-66
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    • 2005
  • Corrosion highly affects the lifetime and performance of machinery metallic components. The effects of shot peening on the fatigue life of Al 7075-T6 under corrosive environment are investigated in this paper. Experimental results show that the fatigue limit of shot peened specimen increases about 52%. That means the fatigue life of metallic components is highly extended by shot peening. The corrosion greatly reduces the fatigue strength depending on the corrosive condition from one week up to one year. In case of shot peened specimen, the corrosion does not reduce the fatigue strength and fatigue life up to six months. It means that the shot peening has superior effectiveness to reduce the influence of corrosion to the metallic materials.

Effects of Shot Peening Time on Microstructure and Electrochemical Characteristics for Cu Alloy (쇼트피닝 시간에 따른 동합금의 조직특성 및 전기화학적 특성의 변화)

  • Han, Min-Su;Hyun, Koang-Yong;Kim, Seong-Jong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.19 no.5
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    • pp.545-551
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    • 2013
  • In this study, shot peening technique was employed with shot peening time for durability improvement and surface modification of copper alloy to investigate the electrochemical characteristics and microstructural variations. As a result of shot peening, roughness was distributed over the surface, and homogenization phenomenon was observed with increasing shot peening time due to the enhancement of coverage. The results revealed that hardness increased for shot peened specimens and particularly 3.5 mins of shot-peening time represented a hardness improvement of 52 %, showing similar electrochemical characteristics to that of the un-peened surface.

Shot peening assisted ion nitriding of H13 steels (H13강의 쇼트피닝을 통한 이온 질화 기구 조사)

  • Lee, Won-Beom;Jo, Gyun-Taek;Kim, Gyeong-Hwang;Mun, Gyeong-Il;Yu, Se-Hun
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.138-138
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    • 2008
  • H13강에 대해 이온질화에 대한 쇼트피닝의 효과를 살펴보았다. 쇼트피닝을 이온질화는 기존이온질화에 비해 높은 경도와 깊은 경화층을 얻을 수 있었다. 이는 쇼트피닝에 의해 결정립계와 전위밀도가 증가함에 따라 질화공정이 가속화된 것으로 보인다.

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A Study on the Relationship between the Short Clip Consumption of Contemporary People's Leisure Time - Focused on "TikTok" (현대인의 여가시간 변화에 따른 쇼트클립 소비현상과의 관련성 연구 -비디오편집 플랫폼 TikTok을 중심으로)

  • Zheng, yu;Choi, dong-hyuk
    • Proceedings of the Korea Contents Association Conference
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    • pp.363-364
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    • 2019
  • 스마트폰이 출현한 이후 사람들은 뉴미디어의 변화에 익숙해있다. 특히 최근 급격히 확장해가는 쇼트클립은 누구나 쉽고 빠르게 제작할 수 있으며, 여유가 없는 현대인들에게 작은 휴식을 주고 있어 인기가 매우 높다. 즉, 현대인의 여가시간 변화에 따른 쇼트클립 이용과 연관성이 높다. 새롭게 출현한 쇼트클립 소비현상에 대한 이해를 바탕으로 현대인의 대중문화의 변화의 특징을 연구할 수 있을 것이다. 본 논문은 뉴미디어의 특징을 정의하고 중국인의 여가시간 변화에 따른 중국의 인기 비디오편집 플랫폼인 'TikTok(틱톡)' 사용량 변화의 연관성을 연구하였다. 이를 통해 쇼트클립 소비문화가 현대인의 삶에 미치는 영향을 이해하는 계기가 되기를 기대한다.

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Development of A Hoist Control Equipment for Shot Ball Transfer (쇼트볼 이송을 위한 호이스트 자동제어 장치 개발)

  • Choi, Jong-Jun;Choi, Young-Kiu
    • 전자공학회논문지 IE
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    • v.47 no.2
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    • pp.47-53
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    • 2010
  • The purpose of this paper is to build on automatic system for the shot ball transfer hoist. The shot ball is used to remove completely paint or leftovers before spreading the new paint on a large vessels surface. The shot ball is made of melted iron through cooling process, and it is transferred to hopper by electromagnet of hoist. Currently, the transfer process of the shot ball is performed by manual operation, and the transfer process is inefficient. So we have developed an automatic system to replace the manual system. The developed automation systems have efficient and accurate position control performance.

A Study on The Comic Presentation Through Three-Dimensional Shot (입체적인 쇼트를 통한 코믹연출연구)

  • Hwang, Kil-Nam;Kim, Jae-Woong
    • The Journal of the Korea Contents Association
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    • v.8 no.2
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    • pp.91-99
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    • 2008
  • When making a comic film, the comic presentation that uses stress and exaggeration is the important subject among other things. In this study we tried to investigate the comic effect using the movement of three-dimensional shot. To conduct this study, we extracted the shot manufactured through the Flow Motion of a 3D Production Program Virtual Camera and a High Speed Motion Picture Camera. The shot manufactured applying this manufacturing skill and using three-dimensional production method for the video contents efficiently made was classified into several scenes. The focus of this study is to search for the factor that makes the atmosphere of a story comic through three-dimensional production shot. According to the shot analysis, three-dimensional production method plays a role in developing more stories on space and time by visualizing stories in three dimensions, which makes the most use of the movement of camera, lens and the utilization of focus. In addition, in the presentation where many comic and exaggerated factors are provided, we used the technology that stresses a scene using the size of a shot and the lasting time and presented the method that exaggerates space using a 3D Production Program Virtual Camera and a High Speed Motion Picture Camera. By reviewing the qualitative improvement and the efficient method on making comic films through the possibility that the atmosphere of this three-dimensional shot can apply to the effect for comic presentation, we tried to approach the comic presentation.

Effect of Shot Peening on the Fatigue of SS400 Weldments (SS400 용접부의 피로강도에 미치는 쇼트 피닝의 영향)

  • Kim, Jin-Hern;Goo, Byeong-Choon;Kim, Hyun-Gyu;Cheong, Seong-Kyun
    • Journal of the Korean Society for Railway
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    • v.12 no.6
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    • pp.895-901
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    • 2009
  • Fatigue fracture of the welded joints of bogie frames is one of unsolved problems. To improve the fatigue strength of the welded joints, various techniques have been applied. In this study, we have investigated the effect of shot peening on the fatigue characteristics of SS400 welded specimens. The fatigue lives of four kinds of welded specimens were examined; welded, PWHT, shot peened, and shot peened after PWHT. The results of the fatigue tests show that the fatigue limit of the shot-peened specimens is higher than that of the welded specimens, and the PWHT specimens have a lower fatigue limit than the welded specimens. It was found that shot peening is a very effective method to improve the fatigue strength of SS400 welded joints.

Characterization of Residual Stress in Shot Peened Al 7075 Alloy Using Surface Acoustic Wave (표면파를 이용한 쇼트피닝된 Al 7075 합금의 잔류응력 평가)

  • Kim, Chung-Seok;Kim, Yong-Kwon;Park, Ik-Keun;Kwun, Sook-In
    • Journal of the Korean Society for Nondestructive Testing
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    • v.26 no.5
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    • pp.291-296
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    • 2006
  • The residual stress in shot-peened Al 7075 alloy was evaluated using surface acoustic wave (SAW). Shot peening was conducted to produce a variation in the residual stress with the depth below the surface under a shot velocity of 30 m/s. The SAW velocity was measured from the V(z) curve using a scanning acoustic microscopy (SAM). The Vickers hardness profile from the surface showed a significant work hardening near the surface layer with a thickness of about 0.25 mm. As the residual stress became more compressive, the SAW velocity increased, whereas as the residual stress became more tensile, the SAW velocity decreased. The variation in the SAW velocity through the shot peened surface layer was in good agreement with the distribution of the residual stress measured by X-ray diffraction technique.