• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.847-853
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• 2013

Micro-dimples on sliding surfaces have been investigated to reduce the frictional forces on metal bearing surfaces; however, for an elastomer, such as thermoplastic polyurethane (TPU), this has not been studied. The material properties of an elastomer are affected by temperature, and this can shorten the life of the elastomer. In this paper, micro-dimples were applied on the surface of an elastomer in order to reduce the frictional heating, which was experimentally investigated using pin-on-disk apparatus while the surface temperature was measured. To obtain optimal design parameters, the design of the experiment was applied, and the shape of the section, size, depth and density of micro-dimples were selected as the design parameters. The results show that the size of the dimple is the most important design parameter.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.84-90
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• 2000

5L laboratory-scale anaerobic digester was used to study the effects of food size and washing rate of food waste on the mixed digestion with sewage sludge. Food waste was crushed with particle diameters of 4mm and 2mm and washed two to three times, and seven to eight times before feeding the batch digester. The digester with crushed of washed food waste showed better performance than that with uncrushed of unwashed to produce methane gas of reduce volatile solids. The digester with 2mm food waste showed 17.4% higher VS/TS reduction rate and 18ml higher methane production rate per gram VS input than that with uncrushed food waste, where VS and TS are volatile solid and total solids in the liquid effluent, respectively. Also food waste crushed eight times gave 8% higher VS/TS reduction rate and 11ml higher methane production rate per gram VS input than unwashed food waste.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.652-657
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• 2003

A wind-tunnel experiment is carried out to examine the applicability of a new passive device, wake disrupter, to flow over a model vehicle for drag reduction. The wake disrupter is a small-size rectangular body attached to a part of the trailing edge of the model vehicle, designed to perturb an essentially two-dimensional nature of wake. A pair of wake disrupter is mounted on the mid-span at the upper and lower trailing edges. From a parametric study about the size of wake disrupter, it is found that the optimum disrupter increases the base pressure by about 20%. Large eddy simulation is also conducted to confirm the experimental result, and shows that the wake is indeed disrupted by the present device.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.4
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• pp.496-506
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• 2001

The effect of corona discharge on soot emission was experimentally investigated. Size and number concentrations of soot aggregates were measured and compared for various voltages. Regardless of the polarity of the applied voltage, the flame length decreased and the tip of flame spreaded with increasing voltage. For the experimental conditions selected, the flame was blown off toward the ground electrode by corona ionic wind. When the negative applied voltage was greater than 3kV(for electrode spacing = 3.5cm), soot particles in inception or growth region were affected by the corona discharge, resulting in the reduction of number concentration. The results show that the ionic wind favored soot oxidation and increased flame temperature. Number concentration and primary particle size greatly increased, when the corona electrodes were located the region of soot nucleation or growth(close to burner mouth).

• Transactions of Materials Processing
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• v.16 no.3 s.93
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• pp.157-162
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• 2007

The hydropiercing process gives a lot of advantages to the tube hydroforming such as cost reduction and high productivity. However it has a drawback, the amount of deflection around the hole is bigger than that of conventional die piercing process. The deflection can cause the problem at the assembly process of stamped parts and hydroformed part. Therefore the reduction of deflection is one of the most important issues for hydropiercing process. In this study, the deflection around hydropierced hole was investigated by experiment. As a result of investigation, the amount of deflection is influenced by the internal pressure, the material thickness' and the size of hole. Especially the hole size is most influencing factor on the deflection around the hydropierced hole.

• Transactions of the Society of Information Storage Systems
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• v.5 no.1
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• pp.1-7
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• 2009

Recently, the growing market demand for small and slim mobile phone cameras requires the size reduction of the camera module. In this paper, an auto-focusing actuator for camera phones is proposed by converting the rotational motion by a rotary VCM actuator into the linear motion using a novel cam structure. This new concept for auto-focusing module enables the reduction of the module thickness and low power consumption. This paper presents the theoretical analysis and optimal design for VCM actuator, cam structure and preload spring. Finally, the experimental results using a prototype with the size of $9.9{\times}9.9{\times}5.9\;mm^3$ are compared with the theoretical predictions.

• Journal of Ginseng Research
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• v.33 no.4
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• pp.305-310
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• 2009

Phenanthrene, one of the polycyclic aromatic hydrocarbons, has been known to be toxic to the environment. In this investigation, the protective effect of red ginseng on phenanthrene-induced oxidative DNA damage was evaluated using Comet assay in A549 cells. Red ginseng's cytoprotective effect on phenanthrene-induced hemolysis was also investigated. This study's findings show that oxidative DNA damage and hemolysis were significantly prevented by red ginseng treatment. Notably, it was found that pulverizing red ginseng into ultra-fine particles even enhanced its protective effects against DNA damage and hemolysis. The results suggest that particle size reduction seems to effectively enhance red ginseng's pharmacological efficacies.

• Management Science and Financial Engineering
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• v.21 no.1
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• pp.25-29
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• 2015

Recently much research efforts have focused on how to manage carbon emissions in logistics operations. This paper formulates a model to determine an optimal shipment size with aims to minimize the total cost consisting not only of inventory and transportation costs but also cost for carbon emissions. Unlike the literature assuming carbon emission factors as a given condition, we consider the emission factors as decision variables. It is allowed to make an investment in improving carbon emission factors. The optimal investment decision is shown to be of a threshold type with respect to unit investment costs. Moreover, the findings in this work provide insights on the various elements of the investment decision and their impacts.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.120-127
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• 1998

This paper deals with the dynamic responses of the multi-span continuous bridge with longitudinal shear keys. It is motivated by a need to understand the effects of longitudinal shear keys which may be used for the reduction of the longitudinal seismic force in continuous bridges. The results show that (1) The force reduction of fixed pier is proportional to the ratio of gap size and elastic maximum displacement of the bridges without shear keys ; (2) The thermal movement has little effect on the response of the continuous bridges with shear keys. Also the simplified equation is proposed to calculate the maximum response of the continuous bridges with longitudinal shear keys. The equation requires only the elastic analysis results of the bridge and the gap size between superstructure and shear keys.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.143-146
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• 2002

A multilayer two-stage bandpass filter using dissimilar low-temperature cofired-ceramic (LTCC) materials is proposed in this paper. The proposed bandpass filter is composed of ceramic substrates with different dielectric constant instead of single ceramic material from top to bottom layer. Inductive elements are designed in a low permittivity ceramic layer to reduce parasitic effects and loss, while capacitive elements are designed in a high pertimitivity ceramic layer for size reduction. The center frequency of the proposed filter is 1.842 GHz, and the performance of the filter is analyzed and compared with the conventional LTCC filter with single material in terms of integration density, size reduction, and performance improvement.