• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1598-1603
• /
• 2004

This paper is an experimental study on the performance characteristic with a variation of capillary diameter and length. The performance characteristic of a refrigeration system is predicted that it is occurring changes of flow pattern and pressure drop in a capillary tube because of reduction of capillary diameter 0.74 to 0.6 mm. The difference between experimental results and analytical results is mainly caused by values of friction factor for using to calculate pressure drop through a small diameter capillary tube under 0.74mm. The experimental equation is derived from capillary tube test data using curve fitting method.

• Journal of Korean Society for Quality Management
• /
• v.27 no.2
• /
• pp.126-142
• /
• 1999

Robust design is an approach to reducing performance variation of quality characteristic values in quality engineering. Taguchi has an idea that mean and variation are handled simultaneously to reduce the expected loss in products and processes. Taguchi parameter design has a great deal of advantages but it also has some disadvantages. The various research efforts aimed at developing alternative methods. In the Taguchi parameter design, the product-array approach using orthogonal arrays is mainly used. However, it often requires an excessive number of experiments. An alternative approach, which is called the combined-array approach, was suggested by Welch et. al. ( 1990) and studied by others. In these studies, only single quality characteristic was considered. In this paper we propose how to simultaneously optimize multiple quality characteristics using desirability function when we used the combined-array approach to assign control and noise factors. An example is illustrated to show the difference between the Taguchi's product-array approach and the combined-array approach.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.10a
• /
• pp.108-111
• /
• 2007

It's important to measure quantitative properties about thermal-nano variation conduct of polymer for producing high quality components using NIL process. NanoScale indents can be used ad cells for molecular electronics and drug deliver, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, it's to evaluate mechanical characteristic of polymer such as PMMA and PC at high temperature for manufacture of nano/micro size of polymer using indenter at high temperature. At high temperature mechanical properties of polymer have extreme variation. Because heating the polymer, it becomes softer than room temperature. In this case it is especially important to study for mechanical properties of polymer at high temperature.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.7 no.6
• /
• pp.1443-1447
• /
• 2012

In this paper, the characteristic of temperature variation was reviewed according to pattern variation. In order to degrade of diagnosis of power supply by using time series data for temperature measured by infrared camera it was transformed into 2 dimension phase plane using Takens embedding method. As a simulation results we cannot completely confirm the characteristic behaviors of nonlinear dynamics in phase plane. However these results has a certain patterns, it requires verification method through additional research in the future.

• Journal of Integrative Natural Science
• /
• v.6 no.1
• /
• pp.39-45
• /
• 2013

Robust design is an approach to reducing performance variation of quality characteristic values in quality engineering. Taguchi has an idea that mean and variation are handled simultaneously to reduce the expected loss in products and processes. In the Taguchi parameter design, the product-array approach using orthogonal arrays is mainly used. However, it often requires an excessive number of experiments. An alternative approach, which is called the combined-array approach, was studied. In these studies, only single quality characteristic (or response) was considered. In this paper we propose how to simultaneously optimize for multiple quality characteristics (or multiresponse) using desirability function when we used the combined-array approach to assign control and noise factors.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.2
• /
• pp.68-73
• /
• 2002

In compared with air insulated switchgear, GIS has a high efficiency and confidence. Insulation method using $SF_6$ gas has a very excellent insulation characteristic for high voltage equipment but has a characteristic that insulation heredity is changed for internal unequal electric field. So analysis of time varying electromagnetic field in GIS is very important for structure design and trouble diagnosis process. In compared with established method, the SNM(Spatial Network Method) in this Paper can observe variation of electromagnetic field with real time and get result very similar to measurement. In order to Know variation of electromagnetic field distribution in fast moving particle, we make used of SNM.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.729-731
• /
• 2003

This Paper describes for vibration characteristic analysis by mode variation of ring type ultrasonic motor. Design for piezoelectric ceramic and elastic body of stator was calculated by Atila using the finite element method(FEM) that considers the resonance frequency, vibration mode and coupling efficiency etc. The propriety of this paper was established through simulation and experiment results of ring type ultrasonic motor.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1177-1179
• /
• 2005

This paper presents the characteristic analysis of slotless tubular type Linear DC Motor with Permanent Magnet excitation as variation of magnetic pole-pitch ratio. The stator armature winding of this motor is designed to wind at inner stator around the mover mounted with permanent magnet. First the practical model of this motor is made and its parameter is measured, after this simulation is carried out. Comparing the simulation results as variation of pole-pitch ratio, it can be seen that the reaching ability makes it useful in applications requiring a small, direct-drive actuator, which is required to extend into a specially constrained environment.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.1
• /
• pp.75-83
• /
• 2001

In this paper, numerical analysis is used to find the effects of inclination of rear end on flow characteristic around an automobile. The reference slant angle of rear end is 28.6$^{\circ}$, the slant angle of rear end is decreased to 24$^{\circ}$, 26.6$^{\circ}$ and also increased to 31.6$^{\circ}$, 36.4$^{\circ}$. The 3-D incompressible Navier-Stockes equations are solved by the iterative time marching scheme. The computed surface pressure coefficients were compared with experimental results and a good agreement has been achieved. The A- and C-pillar vortex and other flow phenomena around the ground vehicle are evidently shown. The variation of aerodynamic coefficients of drag, lift with respect to inclination angle of rear end are systematically studied. The flow characteristic on the automobile surface with respect to change of inclination of rear end have been also studied.

• Journal of Environmental Science International
• /
• v.13 no.1
• /
• pp.27-36
• /
• 2004

Present study analyzed the temporal and spatial characteristics of PM10 pollution in Metropolitan Daegu area based on air pollution monitoring station data and measurements of PM10 concentrations in background area in order to provide essential data for efficient PM10 pollution management. The significant variation of spatial and temporal PM10 concentrations in Daegu area was observed during the study years. The highest maximum PM10 concentration(332 $\mu\textrm{g}$/㎥), average concentration(88 $\mu\textrm{g}$/㎥) and frequency exceeding PM10 daily standard(150 $\mu\textrm{g}$/㎥) were all observed in Namsandong located near a major roadway. The hourly and weekly variations of PM10 concentrations had different pattern for the measurement sites. The monthly and seasonal concentrations exhibited a notable characteristic： the maximum concentration was obtained in spring season, most likely due to Yellow sand effects. Furthermore, this temporal variation of PM10 pollution varied with study site. Meanwhile, the PM10 values measured at the monitoring site, Manchondong, were comparable with those of a control site. The average PM10 concentration ranged from 23 $\mu\textrm{g}$/㎥ to 115 $\mu\textrm{g}$/㎥ with a mean value of 53 $\mu\textrm{g}$/㎥ in the former site and from 22 $\mu\textrm{g}$/㎥ to 91 $\mu\textrm{g}$/㎥ with a mean value of 45 $\mu\textrm{g}$/㎥ in the latter site.