• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.373-380
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• 2010

The purpose of this study was to evaluate the effect of balance training on gait stability. The study population included 17 male high school students who were divided into 3 groups, each of which underwent one of the following types of balance-training programs for 8 weeks: 1 foot standing on cushion foam, trunk muscle training, and inverted body position training. 0, 4, and 8 weeks, the following experiment was performed: The participants were asked to close their eyes and take 17 steps; the stability of forward and sideward movement was determined, and the direction linearity was measured. The results revealed that all the training programs caused a decrease in stride deviation and an increase in the and the stride length, thereby improving the stability of forward movement. All the programs decreased the variation in step width and were thus also effective in improving the stability of sideward movement. The inverted body position training program was considered very effective because the cross point appeared on post hoc graphic analysis after 4 weeks, and the deviation length for 10 m was low, i.e., below 4 cm. All the programs were effective with respect to direction linearity because they decreased the deviation in direction widths. The results indicate that whole-body neurocontrol training is more effective than simple muscle training and local focused balance training, although this neurocontrol training-in the form of inverted body position training-required a longer training period than did the other programs.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.2
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• pp.101-104
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• 2018

Purpose Alpha fetoprotein(AFP) is a fetal serum protein that increases in germ cell tumors derived from liver cancer or egg yolk. AFP test has been used for screening of liver cancer, determination of tumor stage, determination of therapeutic effect, and fetal congenital malformations. The purpose of this study was to compare the results of the four kits, identify the advantages and disadvantages of each kit, and select the appropriate kits for our laboratory. Materials and Methods Blood samples were obtained from 89 patients attending the Seoul national university hospital. Experiments were carried out in accordance with manufacturer's instructions of four companies(A, B, C, D). The precision, recovery, linearity, and sensitivity test were performed for each kit. Results In case of the precision within the measurement, the CV value of the C kit was less than 5% at the low, middle, and high concentrations. The A, B and D kit's the CV value was less than 5% at the concentrations except the low concentration. The recovery rates of the A, B, C, and D kits were $100{\pm}15%$, $100{\pm}30%$, $100{\pm}16%$ and $100{\pm}14%$, respectively. All kits showed good linearity. Sensitivity was measured as 0.5 IU/mL for A, 0.4 IU/mL for B, 0.98 IU/mL for C, and 0.3 IU/mL for D. Conclusion The CV values of the four kits were within 10%, and the correlation coefficients were close to 1 for $R^2=0.978$, $R^2=0.992$ and $R^2=0.8957$. As a result, they are clinically available. Therefore, each laboratory should select the appropriate kit for their experiment's environment.

• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.17-22
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• 2007

Vibration isolation equipments are mostly required in precise measurement and manufacturing system. Among all the vibration isolation equipments, air-spring is the most widely used equipment because of low resonant frequency and high damping ratio. In this study, we used Takagi-Sugeno fuzzy method to design an active vibration isolation system using air-spring, and compared the fuzzy method with passive control method and PID control method. Due to the non-linearity characteristics of air-spring, fuzzy controller was verified to be the most effective both in simulation and experiment.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.190-192
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• 2003

Single phase induction motor is used widely in various electronic appliances by advantage that is simple structure and a low-cost. As high starting torque characteristic is mostly used capacitor run single phase induction motor. In this paper, it is applied that speed controller of Capacitor run single phase induction motor of digital way used general microprocessor, and phase control method used average voltage. Torque get non-linearity to domain of low speed. Unstable domain of low speed is applied of integral cycle control. so it is wide that Speed control domain. Also, PID controller is used to improve characteristic of fast response. The validity of proposed method is verified from simulation and experiment result

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.5
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• pp.641-647
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• 2003

The use of infrared range-finder sensor as the environment recognition system for mobile robot have the advantage of low sensing cost compared with the use of other vision sensor such as laser finder CCD camera. However, it is not easy to find the previous works on the use of infrared range-finder sensor for a mobile robot because of the non-linear characteristic of that. This paper describes the error due to non-linearity of a sensor and the correction of it using neural network. The neural network consists of multi-layer perception and Levenberg-Marquardt algorithm is applied to learning it. The effectiveness of the proposed algorithm is verified from experiment.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.99-104
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• 2004

Micro/meso cutting is getting more important in the fields of precision machining technology. A micro-turning lathe is one of parts to consist the Micro Factory. It accepts stepwise motion actuators that are used for feeding system instead of the conventional mechanism. It is consisted of two Piezoelectric ceramics; one is for feeding the slider, and the other is for clamping the slider in the guide way of the body. The linearity and positional accuracy of the actuators are good enough for high precision motion. The spindle unit is operated with DC motor on the top of the slider. The motion is communicated with miniaturized linear encoder attached on each side of axis. A mono crystal diamond tool is used for cutting tool. This micro-lathe has been made a machining experiment to see the characteristics of micro-machining.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.3
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• pp.48-55
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• 1982

In the present the strain gauge type torque transducers consist of solid shaft as sensor, slip ring, brush and bridge circuit as detecting circuit. So in the case of measuring the low-capacity torque, the error caused by technical mistake in mounting stain gauge on the small sensor and especially by contact resistance between slip ring and brush takes place more than the large sensor. Therefore in this study constant voltage in order to have no effect of contact resistance is supplied to the hollow shaft and Schrobron Bridge Circuit. Through the experiment good results were obtained as follows; linearity, hysterisis and zero drift as static characteristics is within 1% F.S respectively. Also when loading, zero drift is about 2% F.S.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.424-429
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• 2005

In this paper, the response characteristics of one to one resonance on the rectangular cantilever beam in which basic harmonic excitations are applied by nonlinear coupled differential integral equations are studied. This equations have 3-dimensional non-linearity of nonlinear inertia and nonlinear curvature. Galerkin and multi scale methods are used for theoretical approach to one to one internal resonance. Nonlinear response characteristics of 1st, 2nd, 3rd modes are measured from the experiment for basic harmonic excitation. From the experimental result, geometrical terms of nonlinearity display light spring effect and these terms play an important role in the response characteristics of low frequency modes. Dynamic behaviors in the out of plane are also studied.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.12
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• pp.1077-1082
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• 2005

In this paper, it is proposed that the method for constituting pressure control system controlled by Direct Drive Valve (DDV). The DDV has a pressure-feedback-loop itself. It can eliminate non-linearity and uncertainty oi hydraulic system such as uncertain discharge coefficient and change of bulk-modulus. However, the internal feedback-loop can not compensate them perfectly. And fixed gain of the DDV's internal feedback-loop is not proper to apply it through wide pressure range. The steady state error and nonlinear characteristic of transient behaviour is observed in the experiment. So another controller is needed for the desirable performance of the system. To compose the controller, the pressure control system controlled by DDV is modeled mathematically and the parameters of the model are identified using signal-compression method. Then sliding mode controller is designed based on mathematical model. Desirable performance of the pressure control system controlled by DDV is obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.7 s.124
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• pp.565-571
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• 2007

In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by using experiment and simulation. Optimal design for a passive air spring can be obtained by tuning the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the active vibration isolation table with the better isolation performance.