• Journal of Sensor Science and Technology
• /
• v.7 no.6
• /
• pp.437-445
• /
• 1998

The actuator using shape memory alloy spring with bias spring can act as a bidirectional actuator due to the restoring force of the bias spring. In the design of shape memory actuator with bias spring, the required design specifications are the generated force and the necessary stroke. To fulfill these requirements, shape memory alloy spring and bias spring should be designed carefully considering the specified application. In this paper, the novel design method for shape memory alloy actuator with bias spring, which does not require any assumptions from experience, has been proposed and verified by the test of fabricated shape memory alloy actuator. The experimental results show good agreements with calculated values, which guarantees the practical validity of our proposed design method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.7
• /
• pp.923-929
• /
• 2004

A magnetostrictive sensor is a sensor measuring elastic waves. Because of its unique non-contact measurement feature, the sensor receives more attentions in recent years. These sensors have been mainly used to measure longitudinal and torsional waves in ferromagnetic waveguides, but there increases an interest in using the sensor for flexural wave measurement. Since the performance of the sensor is strongly influenced by the applied bias magnetic field distribution, the design of the bias magnetic system providing the desired magnetic field is critical. The motivation of this investigation is to design a bias magnetic system consisting of electromagnets and yokes and the specific objective is to formulate the design problem as a bias yoke topology optimization. For the formulation, we employ linear magnetic behavior and examine the optimized results for electromagnets located at various locations. After completing the design optimization, we fabricate the prototype of the proposed bias magnetic system, and test its performance through flexural wave measurements.

• The Korean Journal of Applied Statistics
• /
• v.28 no.6
• /
• pp.1227-1234
• /
• 2015

Traditional criteria for optimum experimental designs depend on the specifications of the model; however, there will be a dilemma when we do not have perfect knowledge about the model. Box and Draper (1959) suggested one direction to minimize bias that may occur in this situation. We will demonstrate some examples with exact solutions that provide a no-bias design for polynomial regression. The most interesting finding is that a design that requires less bias should allocate design points away from the border of the design space.

• Journal of the Korean Statistical Society
• /
• v.24 no.1
• /
• pp.31-44
• /
• 1995

In fitting a model, there always exists a discrepancy between the fitted model and the true functional relationship. In measuring this discrepancy, Box and Drapper (1959) used the criterion dividing the discrepancy into two parts which are the bias error part and the variance error one in single response case. In this paper, an optimum design which makes these two types of errors as small as possible is found by extending the Box and Drapper criterion to multiple response situation. Especially, a design is found to meat rotatability conditions when we fit a quadratic model to each response fearing cubic bias. Using the central composite design, an application of general results to a specific case is shown to help understanding the material.

• 한국방재학회:학술대회논문집
• /
• 2009.02b
• /
• pp.100.2-100.2
• /
• 2009

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.8
• /
• pp.1263-1268
• /
• 2008

In this paper, the low noise power amplifier for GaAs FET ATF-10136 is designed and fabricated with active bias circuit and self bias circuit. To supply most suitable voltage and current, active bias circuit is designed. Active biasing offers the advantage that variations in the pinch-off voltage($V_p$) and saturated drain current($I_{DSS}$) will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets a gate-source voltage($V_{gs}$) for the desired drain voltage and drain current. Using resistive decoupling circuits, a signal at low frequency is dissipated by a resistor. This design method increases the stability of the LNA, suitable for input stage matching and gate source bias. The LNA is fabricated on FR-4 substrate with active and self bias circuit, and integrated in aluminum housing. As a results, the characteristics of the active and self bias circuit LNA implemented more than 13 dB and 14 dB in gain, lower than 1 dB and 1.1 dB in noise figure, 1.7 and 1.8 input VSWR at normalized frequency $1.4{\sim}1.6$, respectively.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.15 no.3
• /
• pp.33-40
• /
• 2013

This paper focused on investigating the seam strength by cutting direction depending on the fabrics and weave by comparing the tensile strength and elongation of bias, warp and weft of 4 kinds of find cotton fabrics and combining 6 kinds of seam cutting directions. The cutting directions are selected the warp direction, weft direction and 45-degree bias direction. Then, three kinds of directions, the warp/warp direction, the weft/weft direction and the bias/bias directions, and the three different kinds of directions, the warp/weft direction, the warp/bias direction and the weft/bias directions, were finally selected. The results are as follows: The tensile strength of all fabrics was higher in the order of warp, bias and weft direction and tensile elongation was higher in the order of bias, warp and weft direction in almost all fabrics. 100's and 150's cotton fabrics showed the highest seam strength when they were cut in the bias/bias direction. The seam strength of the fabrics cut in the same direction was the highest in the fabrics cut in the bias/bias direction. Four kinds of fabrics demonstrated the similar seam strength. However, for the seam strength of fabrics cut in the different directions, 100's cotton fabrics had the difference of seam strength by direction and weave, but 150's cotton fabrics didn't have any difference in seam strength by direction and weave. As described above, the seam strength was influenced by the cutting direction of fabrics. Accordingly, the seam strength can be improved by changing the cutting direction of seam when making the clothing.

• Communications for Statistical Applications and Methods
• /
• v.9 no.3
• /
• pp.799-808
• /
• 2002

This paper aims at selecting the multi-response design with γ responses minimizing the bias error caused by fitting inadequate models to responses, where the first order models are fitted to Ρ responses fearing the quadratic bias, while to other γ- Ρ responses, the quadratic models are fitted fearing the cubic biases in the cuboidal region of interest. Under the assumption of symmetric design, by minimizing the criterion which represents the amount of error caused by fitting inadequate models, the optimum design was found to be the one having the design moments of second order and the fourth order as 1/3 and l/5, respectively. Examples of the design meeting the required conditions are given for illustration.

• Journal of Integrative Natural Science
• /
• v.5 no.4
• /
• pp.241-245
• /
• 2012

Categorical data collected based on complex sample design is not proper for the standard Pearson multinomial-based chi-squared test because the observations are not independent and identically distributed. This study investigates effects of bias of point estimator of population proportion and its variance estimator to the standard Pearson chi-squared test statistics when the sample is collected based on complex sampling scheme. This study examines the effect under two population homogeneity test. The standard Pearson test statistic can be partitioned into two parts; the first part is the weighted sum of ${\chi}^2_1$ with eigenvalues of design matrix as their weights, and the additional second part which is added due to the biases of the point estimator and its variance estimator. Our empirical analysis shows that even though the bias of point estimator is small, Pearson test statistic is very much inflated due to underestimate the variance of point estimator. In the connection of design-based variance estimator and its design matrix, the bigger the average of eigenvalues of design matrix is, the larger relative size of which the first component part to Pearson test statistic is taking.

• Progress in Superconductivity and Cryogenics
• /
• v.8 no.2
• /
• pp.17-19
• /
• 2006

A novel clock distribution technique for pipelined-RSFQ logics using variable Bias Currents of JTLs as delay-medium is newly proposed. RSFQ logics consist of several logic gates or blocks connected in a pipeline structure. And each block has variable delay difference. In the structure, this clock distribution method generates a set of clock signals for each logic blocks with suitable corresponding delays. These delays, in the order of few to tens of pS, can be adjusted through controlling bias current of JTL of delay medium. While delays with resistor value and JJ size are fixed at fabrication stage, delay through bias current can be controlled externally, and thus, is heavily investigated for its range as well as correct operation within current margin. Possible ways of a standard delay library with modular structure are sought for further modularizing Pipelined-RSFQ applications. Simulations and verifications are done through WRSpice with Hypres 3-um process parameters.