• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.128-135
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• 2004

Generally, heavy electronic products undergo many different types of shocks in transportation from a manufacturer to customers. Cushioning package is used to protect electronic products from severe shock environments. Since the mass distribution of heavy electronic products is usually unbalanced and complex. it is very difficult to design a cushioning package with having high performance by considering only the equivalent stiffness of that. Therefore, when designing the cushioning package for a heavy electronic product, it is necessary to optimize its shape in order to maximize the cushioning performance. In this study, it is focused on designing an optimal shape of cushioning package for a large refrigerator and an efficient design method is suggested by using a dynamic finite element analysis. As the results of this study the optimal shape of cushioning package, which has high cushioning performance and minimized volume, was obtained through the mechanical drop analysis and a optimization process. Through free drop tests of refrigerators, it was identified that the cushioning performance of the cushioning package was improved up by 25% and the its own volume was reduced by 22 ％.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.677-683
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• 2003

Generally, heavy electronic products undergo many different types of shocks in transporting from a manufacturer to customers. Cushioning package materials are used to protect electronic products from severe shock environments. Since the mass distributions of heavy electronic products are usually unbalanced and complex, it is very difficult to design a cushioning package with haying high performance by considering only the equivalent stiffness of that. Therefore, when designing the cushioning material for a heavy electronic product, it is necessary to optimize its shape in order to maximize the cushioning performance. In this study, it is focused on designing an optimal shape of cushioning material for a large-sized refrigerator and an efficient design method is suggested by using a dynamic finite element analysis. As the results of this study, the optimal shape of cushioning material, which has high cushioning performance and minimized volume, was obtained from the drop analysis and a optimization process. From free drop tests of a refrigerator, it was identified that the cushioning performance of the optimal package were improved up to 16 % and the volume of it was reduced in a range of 22 %.

• Journal of Drive and Control
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• v.12 no.4
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• pp.54-59
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• 2015

Due to the tendency to use high speed pneumatic cylinders to improve productivity, cushioning devices are adopted to decelerate the piston motion of pneumatic cylinders to reduce noise, vibration, and impact. This paper presents a comparison of the cushion characteristics of a high speed pneumatic cylinder with a relief valve type cushioning device. The system parameters selected are the damping coefficient, Coulomb friction, heat transfer coefficient, and cracking pressure of the relief valve in the air cushioning device. The integral of the time multiplied square error (ITSE) is used to quantitative measure the cushioning performance to assess the effect of varying these. The cushioning performance achieved good results when the ITSE is a minimum value. In a comparison of the piston displacement and velocity with the variations in system parameters, the heat transfer coefficients are not as significantly affected as the other. Also, the cracking pressure of the relief valve is mainly affected by the pressure and temperature in the cushion chamber.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.1
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• pp.1-6
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• 2009

The impact absorption materials made of synthetic organic chemical product like Expanded Polystyrene(EPS), Expanded Polyethylene(EPE), Expanded Polyurethane(EPU), etc. have been used with general packaging material until the present. But nowadays, the use of these materials is intended to be decreased and to be recycled in connection with environmental pollution. In addition, it has been tried to substitute these materials with non-pollution materials(natural materials) like pulp mould, paper protectors, etc. At the same time, it is required to evaluate and analyze these cushioning materials for cushioning properties based on impact and vibration, in order to make an efficiency on the overall packaging system because they are generally being used by a random choice regardless of the properties of contents and cushioning materials. Therefore, this study provides analyzed data on cushioning properties of various cushioning materials against impact and vibration, and is intended to provide more efficient model for packaging system by minimizing their using amount through choosing an optimal cushioning material as well as intended to lead to the use of nonpollution materials in case these cushioning materials have same cushioning properties.

• Journal of Biosystems Engineering
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• v.41 no.3
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• pp.221-231
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• 2016

Purpose: The objective of this study was to develop cushion curves models and analyze the cushioning performance of multi-layered corrugated structures (MLCS) using a method based on dynamic stress-energy relationship. Methods: Cushion tests were performed for developing cushion curve models under 12 combinations of test conditions: three different combinations of drop height, material thickness, and static stress for each of four levels of energy densities between 15 and $60kJ/m^3$. Results: Dynamic stress and energy density for MLCS followed an exponential relationship. Cushion curve models were developed as a function of drop height, material thickness, and static stress for different paperboards and flute types. Generally, the differences between the shock pulse (transmitted peak acceleration) and cushion curve (position and width of belly portion) for the first drop and the averaged second to fifth drop were greater than those for polymer-based cushioning materials. Accordingly, the loss of cushioning performance of MLCS was estimated to be greater than that of polymer-based cushioning materials with the increasing number of drops. The position of the belly of the cushion curve of MLCS tends to shift upward to the left with increasing drop height, and the belly portion became narrower. However, depending on material thickness, under identical conditions, the cushion curve of MLCS showed an opposite tendency. Conclusions: The results of this study can be useful for environment-friendly and optimal packaging design as shock and vibrations are the key factors in cushioning packaging design.

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.323-329
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• 2010

Physical damages on fruits may be caused by shock and vibration inputs that transmitted from the transporting vehicle through the packaging and cushioning materials to the fruit. In this study, both half sine shock test and trapezoidal shock test were performed by MIL-STD-810F specification in order to investigate and represent the shock response properties such as peak acceleration and shock amplification factors of the pear according to packaging and cushioning materials for optimal packaging design during transportation. Shock excitation data that had been measured on the vehicle operating on the real road were used. Shock response properties measured by half sine shock test were smaller than those measured by trapezoidal shock test. Results represent that corrugation shapes and thickness can significantly affect the cushioning performance than the paper configurations of cushioning pad and showed that fruits may be damaged seriously while transported on the unpaved road without the properly cushioned packaging practices.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.30 no.1
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• pp.53-62
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• 2024

Molded pulp products has become more attractive than traditional materials such as expanded polystyrene foam (EPS) owing to low-priced recycled paper, environmental benefits such as biodegradability, and low production cost. In this study, various design factors regarding compression and cushioning characteristics of the molded pulp cushion with truncated pyramid-shaped structural units were analyzed using a test specimen with multiple structural units. The adopted structural factors were the geometric shape, wall thickness, and depth of the structural unit. The relative humidity was set at two levels. We derived the cushion curve model of the target molded pulp cushion using the stress-energy methodology. The coefficient of determination was approximately 0.8, which was lower than that for EPS (0.98). The cushioning performance of the molded pulp cushion was affected more by the structural factors of the structural unit than by the material characteristics. Repeated impacts, higher static stress, and drop height decreased the cushioning performance. Its compression behavior was investigated in four stages: elastic, first buckling, sub-buckling, and densification. It had greater rigidity during initial deformation stages; then, during plastic deformation, the rigidity was greatly reduced. The compression behavior was influenced by structural factors such as the geometric shape and depth of the structural unit and environmental conditions, rather than material properties. The biggest difference in the compression and cushioning characteristics of molded pulp cushion compared to EPS is that it is greatly affected by structural factors, and in addition, strength and resilience are expected to decrease due to humidity and repetitive loads, so future research is needed.

• The monthly packaging world
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• s.114
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• pp.130-140
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• 2002

• The monthly packaging world
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• s.371
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• pp.62-68
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• 2024

• Korean Journal of Applied Biomechanics
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• v.20 no.1
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• pp.13-23
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• 2010

The purposes of this study was to investigate the biomechanical influence of the walking shoe with a plate spring in the heel and interchangeable heel cushioning elements. Eighteen subjects walked in three conditions: 1) the walking shoes Type A-1 with a soft heel insert, 2) the Type A-2 shoe with a stiff heel insert, 3) a general walking shoe(Type B). Ground reaction forces, leg movements, leg muscle activity and ankle, knee and hip joint loading were measured and calculated during overground walking. During walking, the ankle is a few degrees more dorsiflexed during landing and the knee is slightly more flexed during takeoff with the Type A shoes. As a result of the changes in the walking movement, the ground reaction forces are applied more quickly and the peak magnitudes are higher. Muscle activity of the quadricep, hamstring and calf muscles decrease during the first 25% of the stance phase when walking in the Type A shoes. The resultant joint moments at the ankle, knee and hip joints decrease from 30-40% with the largest reductions occurring during landing.