• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.13 no.1
• /
• pp.25-28
• /
• 2007

Physical damage on fruits and vegetables caused by shock degrades the value of product in the fresh market. In order to design a product/package system to protect the product, the peak acceleration or G force to the product that causes shock damage needs to be determined. Shock cushion packaging is applied to protect goods of all kinds. It can be adapted in their shape to any product to be packed, so that its shock absorbing properties is determined by geometry of the product. The shape of a cushion can be adapted to the expected shock loads. To analyze the response properties of cushion materials for packaging of the pears for optimum packaging design during transportation, shock tests were carried out. Shock acceleration that is happened in pears were appeared very high by $25{\sim}30G$ in the input shock acceleration of 14.1618 G that was measured in transportation road. This means that the pears receive the shock acceleration more than maximum double itself and the damage by this can happen and the shock acceleration increase in case use PE tray cup and PE net in fruits, the use of corrugated fiberboard pad may become one method that it can reduce the damage by the shock in packaging of fruits.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.1
• /
• pp.107-114
• /
• 2011

In this study, a correlation between the roughness of nanoscale lapping surface and its laser scattering pattern has been identified experimentally. The characteristics of laser scattering on a reflected surface are investigated, and a laser scattering mechanism is newly designed by adopting the dark-field method. Laser scattering patterns resulting from nanoscale lapping shape are in the shape of crossed irregular lattice. In addition, optimum laser scattering images are obtained by the design of experiment, and the roughness of nanoscale lapping surface is estimated using regression analysis certain useful features of the laser scattering patterns. The results of fifty experiments on three types of nanoscale lapping surfaces show that the roughness of nanoscale lapping surfaces can be accurately estimated by the proposed mathematical modeling method.

• Nuclear Engineering and Technology
• /
• v.21 no.1
• /
• pp.40-47
• /
• 1989

For the effective design of a beam forming structure of the negative-ion-based neutral beam injector, a computer program based on a particle simulation model is developed for the calculation of charged particle motions in the electrostatic fields. The motions of negative ions inside the acceleration tube of a multiple-aperture triode are computed at finite time steps. The electrostatic potentials are obtained from the Poisson's equation by the finite difference method. The successive overrelaxation method is used to solve the matrix equation. The particle and force weighting methods are used on a cloud-in-cell model. The optimum design of the beam forming structure has been studied by using this computer code for the various conditions of elctrodes. The effects of the acceleration-deceleration gap distance, the thickness of the deceleration electrode and the shape of the acceleration electrode on beam trajectories are exmined to find the minimum beam divergence. Some numerical illustrations are presented for the particle movements at finite time steps in the beam forming tubes. It is found in this particle simulation modelling that the shape of the acceleration electrode is the most significant factor of beam divergence.

• Journal of the Korean Vacuum Society
• /
• v.17 no.5
• /
• pp.408-418
• /
• 2008

The rectangular resonant cavity was designed and characterized as a microwave plasma source for focused ion beam. The optimum cavity was calculated analytically and analyzed in detail by using HFSS(High Frequency Structure Simulator). Since the resonant cavity can be affected by the permittivity of quartz chamber and plasma, the cavity is designed to be changeable in one direction. By observing the microwave input power at which the breakdown begins, the optimum cavity length for breakdown is measured and compared with the calculated one, showing in good agreement with the optimum length reduced by 10cm according to the permittivity change in the presence of quartz chamber. The shape of breakdown power curve as a function of pressure appears to be similar to Paschen-curve. After breakdown, plasma densities increase with microwave power and the reduced effective permittivity in the cavity with plasma results in larger optimum length. However, it is not possible to optimize the cavity condition for high density plasmas with increased input power, because too high input power causes expansion of density cutoff region where microwave cannot penetrate. For more accurate microwave cavity design to generate high density plasma, plasma column inside and outside the density cutoff region needs to be treated as a conductor or dielectric.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.5
• /
• pp.247-253
• /
• 2003

In this study, a numerical analysis of the deposition of gallium arsenide from TMGa and arsine in a horizontal MOCVD reactor is performed to investigate the effect of inlet diffuser shape of reactor on the flow and deposition characteristics. The effects of two geometric parameters (diffuser angle, diffuser shape) on the growth rate, growth rate uniformity, flow uniformity and pressure loss are presented. As a results, it is found that the optimum linear diffuser angle is in the range of $50^{\circ}$∼$55^{\circ}$ and parabolic diffuser in the range of $40^{\circ}$∼$45^{\circ}$ from the viewpoint of growth rate uniformity, flow uniformity and average growth rate. It is also found that variation of diffuser angle has greater impact on growth rate uniformity than average growth rate particularly in parabolic diffuser.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.11
• /
• pp.1125-1130
• /
• 2017

The tooth shapes of serration-type and spline-type reactors are optimized using finite element methods to improve the working life of the part and to lower the stress concentration during rotation resulting from contact with the outer race for a reactor operating with $170^{\circ}C$ transmission oil. The results of thermal expansion analyses between an Al reactor and the steel outer race indicate that, before optimization, the gap between the two parts increases further as the serration-type reactor expands by 0.1 mm and the spline-type one strains by 0.08 mm. Because of shape optimization, a trapezoidal shape is obtained from the initial triangular serration and the rectangular spline of the two reactors. The maximum von Mises stress of the serration-type convertor decreased by 24.5 ％, and by 9.3 ％ for the spline-type convertor. In addition, there is a 13 ％ reduction in the axial thickness, as compared to the initially designed model.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2006.06b
• /
• pp.331-336
• /
• 2006

The rail clamp is the device to prevent that a crane slips along rails due to the wind blast as well as to locate the crane in the set position for loading and unloading containers. The wedge type rail clamp should be designed to consider the structural instability and the durability because it compresses both rail side with large clamping force by the wedge working as the wind speed increases. In this research, there are two methods which are design of experiment and variation technology in used commercial software and shape optimization was performed. The optimum results obtained by the two methods are compared and examined.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.7
• /
• pp.918-925
• /
• 2017

Multiple reflections on exterior equipment with complex shape on naval ships cause unexpectedly high Radar Cross Section (RCS) distributions, and the directions of reradiated electromagnetic waves are hard to predict. Therefore, the optimum arrangement of exterior equipments should be considered according to the Radar Absorbing Structure (RAS) method. In this paper, the optimum arrangement for exterior equipments was determined to reduce multiple reflections and RCS even with complex shapes. The sequential descending arrangement method was used to establish an optimum arrangement algorithm. An LCS-2 type model was selected for optimum exterior equipment arrangements. In order to reduce computational cost, RCS distributions and multiple reflection path analysis of exterior equipments was carried out to select exterior equipments for optimum arrangement, and an optimum arrangement was determined to find positions with minimum RCS values. Also, the RCS reduction effect was analyzed using detectable radar range.

• Journal of Biosystems Engineering
• /
• v.12 no.3
• /
• pp.30-41
• /
• 1987

The geometrical shape of a plow bottom may be the most important factor affecting the performance of a plow for a given soil and operating conditions. There are various designs of the Jaenggi (Korean plow) available commercially, which may be different from each other and from the plow (Western plow) in respect to the shape and performance. This study was intended to investigate the geometrical characteristics of Jaenggi. The coordinate digitizer equipped with 3 potentiometers was designed and manufactured for measurement of the shape of curved plane of moldboard and share. The digitizer was connected to a microcomputer having the data acquisition system. This device was used to analyze the plow bottoms of 5 differently-made Jaenggis and one cylindrical plow. The results of the study are summarized as follows: 1. It was possible to measure easily and quickly the curved plane of plow bottom and to plot the view on three major plans using the coordinate digitizer electrically connected to a microcomputer system. 2. The shape of five Jaenggi bottoms analyzed could be characterized by the cutting angle having the range of $33-42^{\circ}$, the maximum share-lift angle of $41-50^{\circ}$, and the setting angle of moldboard wing of $46-70^{\circ}$. The most critical difference of the shape factors between the Jaenggi and the plow was found in the maximum share-lift angle, the former was more than twice as much as the latter. 3. The analysis of the shape of Jaenggi bottoms showed that the share projections on 3 major plans had a varied triangle, which was quite different from that of plow bottom. Especially, it was analyzed that the shape of furrow slice for the Jaenggi had a skewed rectangle, leaving a considerable height of the ridge at the furrow bottom. 4. The dihedral angle was similar range of $30-85^{\circ}$ for the all bodies investigated, but the directional angle was somewhat different from each other. The difference in directional angle was $5^{\circ}$ for the plow, $20^{\circ}$ for the Jaenggi A and $30^{\circ}$ for the Jaenggi B. 5. Area of the spherical representation region was 0.0328 for the plow, 0.1194 for the Jaenggi A and 0.1716 for the Jaenggi B. This may indicate that the plow came close to a working surface and the Jaenggi A and the Jaenggi B departed from a working surface to a somewhat greater extent.

• Structural Engineering and Mechanics
• /
• v.16 no.5
• /
• pp.519-531
• /
• 2003

Piezoelectric actuators have long been recognised for use in aerospace structures for control of structural shape. This paper looks at active control of the swept shock wave/turbulent boundary layer interaction using smart flap actuators. The actuators are manufactured by bonding piezoelectric material to an inert substrate to control the bleed/suction rate through a plenum chamber. The cavity provides communication of signals across the shock, allowing rapid thickening of the boundary layer approaching the shock, which splits into a series of weaker shocks forming a lambda shock foot, reducing wave drag. Active control allows optimum control of the interaction, as it would be capable of positioning the control region around the original shock position and unimorph tip deflection, hence mass transfer rates. The actuators are modelled using classical composite material mechanics theory, as well as a finite element-modelling program (ANSYS 5.7).