• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1098-1101
• /
• 2003

Complex impedances with frequency and voltage variation were analyzed in ITO/$Alq_3$/Al device structure at thickness 100 nm and 200 nm of $Alq_3$, respectively. At low frequency, complex impedance is mostly expressed by resistive component, and at the high frequency by capacitive component. Also, we have evaluated resistance, capacitance and permittivity.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.5
• /
• pp.462-468
• /
• 1984

The variation of thermal diffusivity with respect to rolling reduction is experimentally determined by flash technique. Copper alloy is used as an experimental and specimens are cut from the slab produced by rolling process with different percent reduction in thickness along the rolling direction and with 30.deg. 60.deg. and 90.deg. angle to the rolling direction. It is found that thermal diffusivity is slightly decreased as rolling reduction increased, and it has tendency that thermal diffusivity is increased slightly as its angle approached to 90.deg. at same rolling reduction.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.41 no.5
• /
• pp.50-58
• /
• 2009

Periodic variation of local paper structure was evaluated using two-dimensional fast Fourier transform (FFT) and spectral analysis. Since the periodic variation could originate from various sources and have different magnitudes and patterns depending on the origins, a complete analysis of local paper structure properties such as local grammage, local thickness, local apparent density and surface topography was proposed in this study. For a commercial copy paper, the individual periodic patterns for each local structural property were identified by using inverse FFT spectrums of the filtered spectrum. The spectral analysis of newsprint sample provided the period of variation quantitatively, which was useful in comparing the origins of the individual periodic patterns of the local structural properties.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.6
• /
• pp.78-89
• /
• 1996

Every mechanical component is fabricated with the variations in its size and shape, and the allowable range of the variation is specified by the tolerance in the design stage. Geometric tolerances specify the size or the thickness of each shape entity itself or its relative position and orientation with respect to datums. Since the range of shape variation can be represented by the variation of the coordinate system attached to the shape, the transformation matrix of the coordinate system would mathematically express the range of shape variation if the interval numbers are inserted for the elements of the transformation matrix. For the shape entity specified by the geometric tolerance with reference to datums, its range of variation can be also derived by propagating the transformation matrices composed of interval numbers. The propagation depends upon the order of precedence of datums.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.4
• /
• pp.67-75
• /
• 2007

This study intends to the adequacy inspection of the room temperature variation rate that is available in the building heat performance evaluation index, so we performed the sensitivity analysis about the room temperature variation rate and the energy consumption in the room. For these purpose, we supposed the models which are composed of the various window area, insulation thickness and ventilation rate. Then we analyzed the simulation using the ESP-r and Seoul weather data. In this research, the pattern of the increasing & decreasing rate of annual load according to the change of the various design factors is similar to the pattern of increasing & decreasing rate of not the K-values but the room temperature variation rate. Also we derive the optimum value of the various design factors and the room temperature variation rate in this analysis model. Further study is to be required the development of convenient tool to use in the real design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.3
• /
• pp.538-545
• /
• 1995

The heat transfer model of ondol heating system is derived in the linear form. The step responses of On-Off controller, PID controller and Position type fuzzy controllers are compared in the sense of several aspects : variation of temperature feedback variable, variation of supplied heat quantity by the boiler, variation of flow rate, variation of thickness of the base, variation of the outdoor temperature.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.09b
• /
• pp.76-80
• /
• 2010

This paper describes that estimation methods for the distribution of consolidation settlements to investigate the influence of distribution characteristics of compression index on the spatial distribution of consolidation settlements. When the variation of compression index is considerable, the spatial distribution of compression index is estimated using ordinary cokriging. The spatial distribution of consolidation settlements estimated by considering both the variation of compression index and void ratio (CASE-1) is different from the conventional mean value of all soil properties (CASE-2). The settlement of CASE-1 shows the larger variation at short distances rather than that of CASE-2. Whereas the spatial settlement distribution of CASE-1 is affected by the spatial distribution of compression index and the thickness of consolidation layer, the distribution of CASE-2 is significantly influenced by the distribution of the thickness of consolidation layer.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2000.06a
• /
• pp.114-120
• /
• 2000

EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication Him is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing of internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the bearing performance of connecting rod big end On internal combustion engine.

• Journal of Welding and Joining
• /
• v.1 no.1
• /
• pp.37-46
• /
• 1983

This paper describes a study of fillet welded joint stressed perpendicular to the weld line. The finite element method was used to determine the stress intensity factor for cruciform joint at weld toe and root cracks according to variation of H/Tp, weld angle and main plate thickness. But, in this study, weld angle was fixed at 45.deg., since the variation of weld angle affect the stress intensity factor little, also main plate thickness was fixed. Pulsating tension fatigue test was done at the second phase of experiment. The work using the concepts of the fracture mechanics on the stable crack growth, was in the correlation of the experimental fatigue stress-life behavior because the fatigue behaviors of various joint geometries are related to the stress intensity factors calculated by F.E.M. analysis. Main results obtained are summarized as follows. 1) According to the propagation of toe crack, the variation of the stress intensity factor at root crack is obvious as H/Tp is smaller. 2) According to the propagation of root cracks, the change of the stress intensity factor of the toe is very large with propagation of root crack. 3) The calculation formula of the stress intensity factor of crack propagation at the root crack was obtained. 4) The calculation formula of the stress intensity factor at the toe cracks was obtained in similar manner. 5) From the results of experiment, the velocity of fatigue crack propagation at the weld toe and root was estimated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05a
• /
• pp.165-167
• /
• 2002

Stable reset and address discharge are very important when they show apparent display. But the shape of reset and address discharge and wall-charge distribution change, according to the variation on temperature. Namely, it is very difficult to show exact picture. This study represents how Dynamic Margin is height and dielectric thickness. When barrier rib height is $100{\mu}m$ and dielectirc thickness is $40{\mu}m$, it is responded the most sensitively by decreasing temperature.