• 전자공학회논문지 IE
• /
• v.47 no.2
• /
• pp.47-53
• /
• 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.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.12
• /
• pp.987-995
• /
• 2016

In this study, the effects of shot peening (SP) on the Vickers hardness of $ZrO_2$ were studied. The size of the shot balls were ${\phi}180{\mu}m$ and ${\phi}300{\mu}m$. The Vickers hardness was measured using an indentation load of 98 N and 294 N. The Vickers hardness was evaluated using Weibull statistical analysis. The scale parameters were significantly evident from the indentation load of 98 N and the shot ball of ${\phi}180 {\mu}m$. Generally, the shape parameters were also evident from the small short ball (180sp). Thus, it is shown that the introduction of a compressive residual stress by SP is an effective technique for increasing the mechanical properties of $ZrO_2$.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.10
• /
• pp.1590-1596
• /
• 2001

The shot peening process is most often used to improve fatigue properties of metal parts. The single most critical parameter of the shot peening process is the shot ball itself. Without the correct quality media, all other shut peening parameters are extraneous and the desired fatigue improvement and consistency of improvement will not be achieved. Shot peening involves modifications of the surface and subsurface condition of a material that can be described by the change of the residual stresses, the hardness, and the surface roughness. This Paper Presents the shot peening to optimize the shot ball parameters. The effect of shot peening parameter on the surface roughness, surface hardness and residual stress are investigated.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.26 no.5
• /
• pp.291-296
• /
• 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.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.11
• /
• pp.1369-1375
• /
• 2011

Shot ball impacts to materials cause residual compressive stress on their surfaces. Improving the fatigue strength of a material that has this residual compress stress is the purpose of the shot peening process. A numerical study was performed to evaluate the effect of the strain rate sensitivity and hardness of the shot ball on the residual compressive stress. We calculated the residual compressive stress due to multiple impact shot peening using ABAQUS 6.9-1. AISI 4340 steel was the material used in this study. We compared the effects of high strain rate sensitivities and low strain rate sensitivities and found that when the material's sensitivity to the strain rate increased, the residual compressive stress decreased. In addition, the residual compressive stress of low-hardness material is higher than that of high-hardness material.

• Journal of Broadcast Engineering
• /
• v.21 no.6
• /
• pp.965-976
• /
• 2016

Recently studies about audio-visual immersion are being carried out due to development of digital video but studies analysing quantitatively the content or climax of video has not carried out. The paper is analysed quantitatively by using shot size, camera angle, camera direction and camera position, objective & subjective which is general component of video expression. We can see the climax effects in the video destroying the principles because there is a rule when they use the component. This thesis analyses shot-list based on video expression in existing movies therefore it can analyse quantitatively several method commonly used in order to make the climax. These suggesting method that can find the part of climax based on analysis of shot-list can be used when you search the specific part of video like long movie or when you search the genre of the movie or when you index the genre. Also it can be very effective in various information services companies offering climax movie which is searched.

• Journal of the Korean institute of surface engineering
• /
• v.35 no.6
• /
• pp.357-362
• /
• 2002

In this study, to improve the effect of the surface treatment, the shape design of shot ball is proposed. The fatigue effects of shot peening by the cut wire shot ball and the rounded cut wire shot ball are compared. The rotary bending and tensile fatigue tests are conducted on a spring steel to evaluate fatigue lives. The residual compressive stresses by the rounded cut wire shot ball is higher than by the rounded cut wire shot ball. This consequently increase the fatigue life and the reliability of surface treatment. Thus, to obtain optimum, repeatable and reliable shot peening effect the shape of the shot ball must be round.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.12
• /
• pp.2647-2655
• /
• 2002

This research presents an analytical model to investigate the stability due to the ball bearing waviness i n a rotating system supported by two ball bearings. The stiffness of a ball bearing changes periodically due to the waviness in the rolling elements as the rotor rotates, and it can be calculated by differentiating the nonlinear contact forces. The linearized equations of motion can be represented as a parametrically excited system in the form of Mathieu's equation, because the stiffness coefficients have time -varying components due to the waviness. Their solution can be assumed as a Fourier series expansion so that the equations of motion can be rewritten as the simultaneous algebraic equations with respect to the Fourier coefficients. Then, stability can be determined by solving the Hill's infinite determinant of these algebraic equations. The validity of this research is proved by comparing the stability chart with the time responses of the vibration model suggested by prior researches. This research shows that the waviness in the rolling elements of a ball bearing generates the time-varying component of the stiffness coefficient, whose frequency is called the frequency of the parametric excitation. It also shows that the instability takes place from the positions in which the ratio of the natural frequency to the frequency of the parametric excitation corresponds to i/2 (i=1,2,3..).

• Journal of the Korean Society of Industry Convergence
• /
• v.26 no.5
• /
• pp.725-731
• /
• 2023

In this study, the harmless crack size was evaluated using carburized, quenched-tempered SCM822H steel. The possibility of detecting cracks that reduce the fatigue limit by non-destructive inspection was evaluated. The conclusions obtained are as follows. The retained austenite of surface was reduced by SP. About 35% and 65% of the retained austenite on the surface were transformed into strain-induced martensite, increasing the hardness by 79HV and 122HV over the as-received material. The maximum compressive residual stresses introduced on the surfaces were -695 MPa and -688 MPa, respectively. The fatigue limit increased by 1.48 times and 1.67 times, respectively, compared to the as-received material. The harmless crack size of SP specimen was determined differently depending on the shot ball size.

• Journal of Digital Contents Society
• /
• v.18 no.5
• /
• pp.849-858
• /
• 2017

With the fast improvement of software and hardware technology of Virtual Reality, VR(Virtual Reality) film get attention for the new possibility of future film. Already, the production of virtual reality film festivals and Hollywood films is highly active, but it is still poorly related to virtual reality films in Korea. Due to this, this research analyze VR film with Realism films and Post-modernism films in four aspects that are film's frame(Mise-en-$Sc{\grave{e}}ne$), shot(montage), vew point and interactivity to deduct characteristics of VR film. Moreover, we also deduct an esthetical characteristic of VR films beyond the Realism films and Post-modern Films through analysing various VR films. This can be said as 'Digital Realism' that is come from the viewers' positive interaction and realization of Realism through Virtual Reality technology. There will be a successful development of VR film based on this research that analyse suitable directing method for Virtual Reality environment. At last, this research focused on characteristics of digital realism aspect for HMD based first person view VR animation .