• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.638-641
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• 2008

Computational investigation was conducted to study the effects of the shape parameter of shroud on the performance of the outdoor unit of an air-conditioners. For this study the Design of Experiment(4-factor 3-level) was created and the an automatic program was composed using VBA to reduce the load of pre-process for CFD. The estimated mathematical equation was produced from this analysis and it was found that the gap between fan and shroud affects more heavily than the other parameters. As a result, the composition of the best parameters was verified that its flow rate was increased by 10 percents and sound pressure level was reduced by 1.2 dBA compare with the worst. And finally, a kind of Propeller fan with blades which were attached to the shroud, so-called 'ProBeller Fan' was introduced in this study.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.184-190
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• 2010

Recently, the polishing process using magnetorheological fluids(MR fluids) has been focused as a new ultra-precision polishing technology for micro and optical parts such as aspheric lenses, etc. This method uses MR fluid as a polishing media which contains required micro abrasives. In the MR polishing process, the surface roughness and material removal rate of a workpiece are affected by the process parameters, such as the properties of used nonmagnetic abrasives(particle material, size, aspect ratio and density, etc.), rotating wheel speed, imposed magnetic flux density and feed rate, etc. The objective of this research is to predict MRR according to the polishing conditions based on the multiple regression analysis. Three polishing parameters such as wheel speed, feed rates and current value were optimized. For experimental works, an orthogonal array L27(313) was used based on DOE(Design of Experiments), and ANOVA(Analysis of Variance) was carried out. Finally, it was possible to recognize that the sequence of the factors affecting MRR correspond to feed rate, current and wheel speed, and to determine a combination of optimal polishing conditions.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1885-1890
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• 2008

3-D heterogeneous nucleation was simulated by classical molecular dynamics (MD), where the Lennard-Jones (LJ) gas and solid cluster-seed molecules have argon and aluminum properties, respectively. There are three shapes of cluster-seeds, cube, rod, and sphere, and three classes of masses and the simulation took place under nine supersaturation ratios, making a total of 81 calculations. Results show that the dimension of the cluster-seed highly affects the rates of cluster development. In order to analyze heterogeneous nucleation above and below the critical supersaturation ratio, growth rate and liquefaction rate were separately defined to supplement the investigation. Design of experiments (DOE) was used for analysis which displayed that the shape and mass of the cluster-seed are prominent for the growth rate, while the supersaturation ratio is most significant followed by the mass for liquefaction rate. The significance of the supersaturation ratio for overall liquefaction suggests that thermal diffusion is more dominant than mass interactions for this system.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.13-19
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• 2008

A Wire-woven Bulk Kagome (WBK) is the new truss type cellular metal fabricated by assembling the helical wires in six directions. The WBK seems to be promising with respect to morphology, fabrication cost, and raw materials. In this paper, first, the geometric and material properties are defined as the main design parameters of the WBK considering the fact that the failure of WBK is caused by buckling of truss elements. Taguchi approach was used as statistical design of experiment(DOE) technique for optimizing the design parameters in terms of maximizing the compressive strength. Normalized specific strength is constant regardless of slenderness ratio even if material properties changed, while it increases gradually as the strainhardening coefficient decreases. Compressive strength of WBK dominantly depends on the slenderness ratio rather than one of the wire diameter, the strut length. Specifically the failure of WBK under compression by elastic buckling of struts mainly depended on the slenderness ratio and elastic modulus. However the failure of WBK by plastic failed marginally depended on the slenderness ratio, yield stress, hardening and filler metal area.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.768-772
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• 2008

Various scanning systems have been studied in many industrial areas to acquire a range data or to reconstruct an explicit 3D model. Currently optical technology has been used widely by virtue of noncontactness and high-accuracy. In this paper, we describe a 3D laser scanning system developped to reconstruct the 3D surface of a large-scale object such as a curved-plate of ship-hull. Our scanning system comprises of 4ch-parallel laser vision modules using a triangulation technique. For multi laser vision, calibration method based on least square technique is applied. In global scanning, an effective method without solving difficulty of matching problem among the scanning results of each camera is presented. Also minimal image processing algorithm and robot-based calibration technique are applied. A prototype had been implemented for testing.

• The Korean Journal of Nuclear Medicine
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• v.14 no.1
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• pp.23-28
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• 1980

This is an analysis of 32 patients who received long continuous corticosteroid drug due to some diseases. Patients were collected from June 1976 to March 1980. Blood cortisol level, variation of diurnal rhythm and side effects were studied. The Result as follows: 1. Side effects were observed in 24 patients(75%) and most common complaint was obesity. 2. Diurnal rhythm analysed by Doe's method shows abnormal diurnal rhythm is 21 out of 32(66%). 3. Mean durations or therapy of abnormal diurnal rhythm and normal diurnal rhythm were $55.7{\pm}4.4$ months and $43.9{\pm}7.0$ months respectively which shows statistically significant difference. 4. Mean cortisol value of steroid treated patients were lower than normal. 5. Reverse diurnal rhythm was 4 out of 21 patients. 6. 8 A.M. cortisol value is lower than 2 times of 8 P.M. in all patients who showed abnormal diurnal rhythm except one.

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.54-62
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• 2012

In this experiment, the optimum concentration of polyols which were used for making transparent soaps was determined using design of experiment (DOE) method. Dipropylene glycol and 1,3 butylene glycol with short chains enhanced the transparency of soap, however, polyethylene glycol 400, glycerin and diglycerin made the soap opaque. The hardness of soap was increased as increasing the concentration of propylene glycol, diglycerin, dipropylene glycol and polyethylene glycol 400. The hardness, transparency, absorbance of water, and friction solubility could be optimized by controlling the concentration of dipropylene glycol, polyetylene glycol, sugar, and triethanolamine.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.718-724
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• 2010

The Unreal Engine is a free game engine developed by Epic Games. In this paper, we propose a First Person Shooter (FPS) game development using free Unreal Development Kit. The merit of Unreal engine provide a hight degree of portability, and it is a tool used by many game developers today, supporting a multitude of platforms on personal computers and many video game consoles with free toolkit. But it is required high-performance PC to develop game. This toolkit doe s not high-quality computer programming skill, just possible to develop FPS game easily.

• Journal of Auto-vehicle Safety Association
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• v.6 no.2
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• pp.49-54
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• 2014

Development in vehicle industry could increase interest in children's safety recently. However the research of children safety is not being conducted as many as that of adult's. Especially the basic study for the vehicle crash on-board children was not much. This study focused on the effect of seatbelt anchorage points to evaluate children's safety in frontal crash. The current regulation of the seatbelt anchorage points is suitable for ranged from female 5% to male 95%. The assessment of children's safety at buckle up of no used CRS(child restraint system) was performed using frontal sled tests. The frontal crash pulse in sled tests was designed to the average of about 30 KNCAP frontal crash pulses. To reduce number of experiments, DOE is used. The Q6 child dummy and standard seat in UN R 129 were used. According to the analysis of test results, children's safety has been influenced by the points of seatbelt anchorage.

• Korean Journal of Computational Design and Engineering
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• v.18 no.5
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• pp.359-366
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• 2013

In the lower arm design process, a tolerance optimization of the variance of design variables should be preceded before manufacturing process, since it is very cost-effective compared to a strict management of tolerance of products. In this study, a design of experiment (DOE) based on response surface model (RSM) was carried out to find optimized design variables of the lower arm, which can meet a given requirement of probability constraint for the process capability index (Cpk) of the weight and maximum stress. Then, the design space was explored by using the central composite design method, in which the 2nd order Taylor expansion was applied to predict a standard deviation of the responses. The optimal solutions satisfying the probability constraint of the Cpk were found by considering both of the mean value and the standard deviation of the design variables.