• Journal of the Korean Mathematical Society
• /
• v.36 no.4
• /
• pp.787-811
• /
• 1999

Let M be the maximal ideal space of the Banach algebra $H^{\infty}$ of bounded analytic functions on the open unit disc $\triangle$. For a positive singular measure ${\mu}\;on\;{\partial\triangle},\;let\;{L_{+}}^1(\mu)$ be the set of measures v with $0\;{\leq}\;{\nu}\;{\ll}\;{\mu}\;and\;{{\psi}_{\nu}}$ the associated singular inner functions. Let $R(\mu)\;and\;R_0(\mu)$ be the union sets of $\{$\mid$\psiv$\mid$\;<\;1\}\;and\;\{$\mid${\psi}_{\nu}$\mid$\;<\;0\}\;in\;M\;{\setminus}\;{\triangle},\;{\nu}\;\in\;{L_{+}}^1(\mu)$, respectively. It is proved that if $S(\mu)\;=\;{\partial\triangle}$, where $S(\mu)$ is the closed support set of $\mu$, then $R(\mu)\;=\;R0(\mu)\;=\;M{\setminus}({\triangle}\;{\cup}\;M(L^{\infty}(\partial\triangle)))$ is generated by $H^{\infty}\;and\;\overline{\psi_{\nu}},\;{\nu}\;{\in}\;{L_1}^{+}(\mu)$. It is proved that %d{\theta}(S(\mu))\;=\;0$ if and only if there exists as Blaschke product b with zeros $\{Zn\}_n$ such that $R(\mu)\;{\subset}\;{$\mid$b$\mid$\;<\;1}\;and\;S(\mu)$ coincides with the set of cluster points of $\{Zn\}_n$. While, we proved that $\mu$ is a sum of finitely many point measure such that $R(\mu)\;{\subset}\;\{$\mid${\psi}_{\lambda}$\mid$\;<\;1}\;and\;S(\lambda)\;=\;S(\mu)$. Also it is studied conditions on \mu for which $R(\mu)\;=\;R0(\mu)$.

• Journal of the Korean Magnetics Society
• /
• v.3 no.1
• /
• pp.61-64
• /
• 1993

We have constructed a hysteresis loop tracer in order to measure the magnetic properties of amorphous wires under variable tensile stress. It has a force range of 0 N to 20 N and a magnetizing frequency of 1 kHz to 20 kHz. Using the ac-hysteresis loop tracer, we can measure the magnetic properties(maximum magnetic induction $B_{max}$, residual magnetic induction $B_{r}$, coercive field strength $H_{c}$, etc.) of amorphous wires with precision of 1% under variable tensile stresses.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.20 no.41
• /
• pp.33-40
• /
• 1997

The main objective of this study is to analysis the relationship between productivity measurement model which describe and explain R&D(Research & Development) productivity based on production function of Cobb-Douglas and the structure of the R&D investment. The model focuses on the variables related to R&D investment in order to measure the efficiency of R&D largely. So, the proposed model describe the relationship between output(or / input) and factors of production such as capital cost, labor cost and R&D expense, etc. These factors are associated with a signigicant positive correlation between productivity and R&D investment.

• Journal of the Korean Mathematical Society
• /
• v.36 no.1
• /
• pp.193-207
• /
• 1999

Let ${\gamma}$ : Ilongrightarrow R2 be a sufficiently smooth curve and $\sigma$${\gamma}$ be the affine arclength measure supported on ${\gamma}$. In this paper, we study the Lp - improving properties of the convolution operators T$\sigma$${\gamma}$ associated with $\sigma$${\gamma}$ for various curves ${\gamma}$. Optimal results are obtained for all finite type plane curves and homogeneous curves (possibly blowing up at the origin). As an attempt to extend this result to infinitely flat curves we give and example of a family of flat curves whose affine arclength measure has same Lp-improvement property. All of these results will be based on uniform estimates of damping oscillatory integrals.

• Journal of Sensor Science and Technology
• /
• v.24 no.3
• /
• pp.208-213
• /
• 2015

The purpose of this study is to optimize the design of a capacitive pressure sensor element using the simulation of electrical characteristics. The simulation of the ceramic sensor diaphragm ($Al_2O_3$) was performed by permitting pressure to change the curvature of the diaphragm. The pressure capacitance ($C_P$) was increased from 19.63 pF to 15.26 pF by applying pressure because the distance between the electrodes has been changed from $30{\mu}m$ to $15{\mu}m$. When the thickness of the diaphragm was changed to 0.46~0.52 mm, a larger capacitance change showed in accordance with the reduced thickness, which means an increase of sensitivity. However, considering the viewpoint of the signal linearity, it was selected for the optimum thickness of the diaphragm to 0.50 mm. The designed sensor element based on simulated results was tested to measure the output characteristics. Comparing of simulated and measured results, there was a margin of error of approximately 2%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.1
• /
• pp.31-37
• /
• 1999

In order to predict thermodynamic performance of refrigeration system, it is required to know the oil concentration of the refrigerant/oil mixture. The current method to measure the oil concentration is to extract the working mixture and then to measure the oil weight. However, it is Quite necessary to estimate oil concentration without any extraction of the working fluid. In this study a new method and working equation is presented as follows. It is based on the measurement of spedific gravity and temperature : $$C=a+b{\times}t+c{\times}t^2+(d+e{\times}t+f{\times}t^2){\times}SG$$ C is oil concentration, t is temperature($^{\circ}C$), SG is specific gravity of mixture and a~f is coefficients. The oil concentration ranges over 0~12 wt% and the temperature ranges over $20{\sim}50^{\circ}C$. The specific gravity and temperature are measured using the on-line densimeter and thermometer. This working equation enables to predict the oil concentration without any extraction of the mixture. This equation can be applied for R-12/Naphthenic oil and R-134a/POE oil oiquid mixtures.

• Korean Journal of Mathematics
• /
• v.6 no.2
• /
• pp.291-298
• /
• 1998

The $L^p-L^q$ mapping properties of convolution operators with measures supported on curves in $\mathbb{R}^3$ have been studied by many authors. Oberlin provided examples of nondegenerate compact space curves whose arclength measures enjoy $L^p$-improving properties. This was later extended by Pan who showed that such properties hold for all nondegenerate compact space curves. In this paper, we will prove that the operator norm of the convolution operator with the arclength measure supported on a nondegenerate compact space curve depends only on certain quantities of the underlying curve.

• Journal of Biomedical Engineering Research
• /
• v.29 no.4
• /
• pp.286-294
• /
• 2008

This work investigates the characteristics of brain interactions of experienced Zen-Buddhist practitioners by obtaining multichannel EEG (electroencephalogram) data. Brain interactions were compared among three phases-40-minute meditation (M), 5-minute Chakra-focusing practice (Z) and rest with closed eyes (R). The similarity index S, developed in nonlinear dynamical system theory, was employed to measure the degree of possibly asymmetric coupling. Meditators exhibited, overall, stronger interactions among multiple cortical areas in meditation stages M and Z than in the R state. This enhancement was greater in the M stage when the meditator was accompanied by a thought-free and fully consciousness state. In the high-frequency band (>13Hz), the interdependence was also higher in both meditation stages than at baseline rest. However, the interaction strength, especially in the posterior regions, was greatest in the Z stage, which involved internal attention. Few electrode pairs were observed with significant pair-wise asymmetry in the Z state. The similarity is a possible characteristic of dense reciprocal and strong mutual interactions between multiple cortical areas during meditation - especially in the Z state in the high-frequency band. These results demonstrate that profound Zen meditation induces various dynamic states in different phases of meditation, possibly reflected by nonlinear interdependence measure.

• Korean Journal of Agricultural Science
• /
• v.40 no.1
• /
• pp.53-59
• /
• 2013

Analysis of load data during field operations is highly important for optimum design of power drive lines for agricultural tractor. Objective of the paper was to analyze field load data using FFT to determine frequency and the energy levels of meaningful cyclic patterns. Rotary tillage, plowing, baling, and wrapping operations were selected as major field operations of agricultural tractor. An agricultural tractor with power measurement system was used. The tractor was equipped with strain-gauge sensors to measure torque of four driving axles and a PTO axle, speed sensors to measure rotational speed of the driving axles and an engine shaft, pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to calculate power requirement. In rotary tillage, calculated frequency was decreased as travel speed increased. In baler operation, calculated frequency was increased as PTO speed was increased. The calculated peak frequency levels and expected levels were similar. Results of the study would provide information on power utilization patterns and on better design of power drive lines.

• Journal of Korea Technology Innovation Society
• /
• v.3 no.2
• /
• pp.48-60
• /
• 2000

An effort has been made in this paper to measure the project manager's reaction to R&D project evaluation and present the useful information related to rebuilding an R&D evaluation system. Results of this study show that project manager's reaction is related to the selection of reasonable items for evaluation, the rater's expertise, the project manager's participation in evaluation process and so on. Accordingly, managers of the research institute have to set up the evaluation system after deeply considering these results.