• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1377-1379
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• 1996

In this paper, each parameter was identified by the gradient descent method to overcome difficulty deciding fuzzy rules of FLC for the unknown process and the type of membership Junctions. Usually PID or optimal control theories have been mostly usee in control field so far. However, optimal control requires much time for calculation because of adaptation for disturbance and nonlinearity. And intricate technique such as MRAS which can be realized only by an expert are limited to be used in the systems requiring rapid and precise response because of comparatively longer calculating time and complicateness. Gradient descent method is a method to find Z minimizing a function about a certain vector Z. And required output of FLC is gained using gradient approaching method in order to adapt control rule parameters of FLC. Simulation proved validation of this algorithm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.70-73
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• 2007

The forming characteristics of cup-rod combined extrusion process were investigated with process parameter change. Simultaneous forward rod extrusion and backward cup extrusion was conducted with magnesium alloy, AZ31B. Process parameters such as forward extrusion ratio, backward extrusion ratio, and working temperature were controlled in a specific region and the effects of the parameter change were examined. Surface crack was developed in a certain state of the process parameters combination. The crack-free forming limit of the alloy in the combined process was disclosed by the parameter study. The microstructures of the initial and extruded workpieces were observed.

• Structural Engineering and Mechanics
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• v.37 no.1
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• pp.61-77
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• 2011

Static and dynamic responses of a completely free elastic beam resting on a two-parameter tensionless Pasternak foundation are investigated by assuming that the beam is symmetrically subjected to a uniformly distributed load and concentrated load at its middle. Governing equations of the problem are obtained and solved by paying attention on the boundary conditions of the problem including the concentrated edge foundation reaction in the case of complete contact and lift-off condition of the beam ina two-parameter foundation. The nonlinear governing equation of the problem is evaluated numerically by adopting an iterative procedure. Numerical results are presented in figures to demonstrate the non-linear behavior of the beam-foundation system for various values of the parameters of the problem comparatively by considering the static and dynamic loading cases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1139-1146
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• 1999

Reliability analysis of structures based on fracture mechanics requires knowledge on statistical characteristics of the parameter C and m in the fatigue crack growth law, $da/dN=C({\Delta}K)^m$. The purpose of the present study is to investigate if it is possible to predict fatigue crack growth rate by only the fluctuation of the parameter C. In this study, Paris-Erdogan law is adopted, where the author treat the parameter C as random and m as constant. The fluctuation of crack growth rate is assumed only due to the parameter C. The growth resistance coefficient of material to fatigue crack growth (Z=1/C) was treated as a spatial stochastic process, which varies randomly on the crack path. The theoretical crack growth rates at various stress intensity factor range are discussed. Constant ${\Delta}K$ fatigue crack growth tests were performed on the structural steel, SM45C. The experimental data were analyzed to determine the autocorrelation function and Weibull distributions of the fatigue crack growth resistance. And also, the effect of the parameter m of Paris' law due to variation of fatigue crack growth resistance was discussed.

• Atmosphere
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• v.23 no.3
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• pp.265-273
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• 2013

To investigate properties of cloud and rainfall occurred at Boseong on 10 July 2012, Raindrop Size distributions (RSDs) and other parameters were analyzed using observation data collected by Micro Rain Radar (MRR) and PARticle SIze and VELocity (PARSIVEL) disdrometer located in the National center for intensive observation of severe weather at Boseong in the southwest of the Korean peninsula. In addition, time series of RSD parameters, relationship between reflectivity-rain rate, and vertical variation of rain rates-fall velocities below melting layer were examined. As a result, good agreements were found in the reflectivity-rain rate time series as well as their power relationships between MRR and PARSIVEL disdrometer. The rain rate was proportional to reflectivity, mean diameter, and inversely proportional to shape (${\mu}$), slope (${\Lambda}$), intercept ($N_0$) parameter of RSD. In comparison of the RSD, as rain rate was increased, the slope of RSD became less steep and the mean diameter became larger. Also, it was verified that reflectivities are classified in three categories (Category 1: Z (reflectivity) > 40 dBZ, Category 2: 30 dBZ < Z < 40 dBZ, Category 3: Z < 30 dBZ). As reflectivity was increased, rain rate was intensified and larger raindrops were existed, while reflectivity was decreased, shape (${\mu}$), slope (${\Lambda}$), intercept ($N_0$) parameter of RSD were increased. We expected that these results will lead to better understanding of microphysical process in convective rainfall system occurred during short-term period over Korean peninsula.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1200-1209
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• 1999

Prediction model was composed by optimal parameter estimation from best fitting on reactant temperature profile, inlet and outlet temperature of coolant and yield of dual fixed-bed catalytic reactor(FBCR) which was measured in the industrial field. In order to design the FBCR which could obtain maximum conversion and yield, we investigated the effect of catalyst bed length and reactor radius changes. An uniform activity FBCR showed the best performance at z = 2.8 m of total catalysst bed length in case of reactor radius r = 0.01241 m and z =2.80 m(upper layer: 1.88 m, lower layer: 0.92 m) under reactor radius r = 0.01254 m for a dual activities FCBR. In case of reactor radius changes, the axial temperature profile and maximum radial temperature was rapidly risen for radius increase. The reactor radius decrease showed the opposite result.

• Fibers and Polymers
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• v.7 no.4
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• pp.450-456
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• 2006

The objectives of this study were to investigate physiological and psychological responses to the rustling sound of Korean traditional silk fabrics and to figure out objective measurements such as sound parameters and mechanical properties determining the human responses. Five different traditional silk fabrics were selected by cluster analysis and their sound characteristics were observed in terms of FFT spectra and some calculated sound parameters including level pressure of total sound (LPT), Zwicker's psychoacoustic parameters - loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z), and sound color factors such as ${\Delta}L\;and\;{\Delta}f$. As physiological signals, the ratio of low frequency to high frequency (LF/HF) from the power spectrum of heart rate variability, pulse volume (PV), heart rate (HR), and skin conductance level (SCL) evoked by the fabric sounds were measured from thirty participants. Also, seven aspects of psychological state including softness, loudness, sharpness, roughness, clearness, highness, and pleasantness were evaluated when each sound was presented. The traditional silk fabric sounds were likely to be felt as soft and pleasant rather than clear and high, which seemed to evoke less change of both LF/HF and SCL indicating a negative sensation than other fabrics previously reported. As fluctuation strength(Z) were higher and bending rigidity (B) values lower, the fabrics tended to be perceived as sounding softer, which resulted in increase of PV changes. The higher LPT was concerned with higher rating for subjective loudness so that HR was more increased. Also, compression linearity (LC) affected subjective pleasantness positively, which caused less changes of HR. Therefore, we concluded that such objective measurements as LPT, fluctuation strength(Z), bending rigidity (B), and compression linearity (LC) were significant factors affecting physiological and psychological responses to the sounds of Korean traditional silk fabrics.

• Nuclear Engineering and Technology
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• v.11 no.4
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• pp.295-301
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• 1979

For thermal-neutron-induced fission of $U^{235}$, nuclear charge distribution in the light part of the primary products has been calculated by using several postulates of charge distribution in the fission fragments. By comparing these values with the experimental results, it is revealed that those models are not appropriate for predicting the nuclear charge distribution in the fission fragments. The variation in the most probable charge, $Z_{P}$, of the isobaric distribution for the fission fragments and the charge for a mass given by unchanged charge density, $Z_{UCD}$, is turned out to be small as a function of mass. The parameter, $Z_{P}$ $-Z_{UCD}$, varies from 0.45 to 0.5 in charge units. The nuclear charge dispersion, $\sigma$, shows about 0.5 charge units for the fission fragments. Neutron odd-even effect in fission products could not be revealed clearly without considering the odd-even effect of prompt neutron emission.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.169-174
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• 2002

Make Photochromic lens Photochromism estimation method, and gouge photochromic lens and investigated UV light source to apply. UV light source irradiation ago and after wavelength dependence of photo-transmittance (T%) of darkening and fading state by do optical equipment which is consisted of spectrophotometer, light source, power meter and detecter. Use relative ratio value of maximum $T%{\times}{\lambda}$ area and saturated state area in light off. Dependences estimation introduced darkening efficiency $(K_d)=(1-C_1/A_1)/t_{on}$ relationship value course fading efficiency$(K_f)=(C_2/A_2)/t_{on}$ value during Photochromism's irradiation time in Photochromic lens. Wavelength dependence of transmittance (T%) has form of $T_m+T_1{\exp}[-(x_0-t)/a]$ in Darkening course fading state. Can receive each estimation parameter value as result that apply Photochromism's estimation parameter Z, $K_d$, $K_f$ in Photochromic lens.

• Journal of the Korean Magnetics Society
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• v.10 no.3
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• pp.106-111
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• 2000

The magnetic thin films can be prepared without vacuum process and under the low temperature (<100 $^{\circ}C$) by ferrite plating. We have performed ferrite plating of M $n_{x}$Z $n_{0.22}$F $e_{2.78-x}$ $O_4$(x=0.00~0.08) films and N $i_{x}$Z $n_{0.22}$F $e_{*}$2.78-x/ $O_4$(x=0.00~0.15) films on cover glass at the substrate temperature 90 $^{\circ}C$. The crystal structure of the samples has been identified as a single phase of polycrystal spinel structure by x-ray diffraction technique. The lattice constant in the M $n_{x}$Z $n_{0.22}$F $e_{2.78-x}$ $O_4$films increases but in the N $i_{x}$Z $n_{0.22}$F $e_{*}$2.78-x/ $O_4$films decrease with the composition parameter, x. The saturation magnetization in the M $n_{x}$Z $n_{0.22}$F $e_{2.78-x}$ $O_4$films does not greatly change, in agreement with observations on bulk samples.k samples.k samples.