• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.1
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• pp.1-15
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• 2004

Dynamic analyses were carried out to study the seismic response of high-rise steel moment-resisting frames in sixteen story buildings. The frames are intentionally designed by three different design procedures; strength controlled design. strong column-weak beam controlled design. and drift controlled design. The seismic performances of the so-designed frames with vertical mass irregularities were discussed in view of drift ratio. plastic hinge rotation, hysteretic energy input and stress demand. A demand curve of hysteretic energy inputs was also presented with two earthquake levels in peak ground accelerations for a future design application.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.625-633
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• 2005

Vehicle drift was reduced using statistical six sigma tools. The study was performed through four steps: M (measure), A (analyze), I (improve), and C (control). Step M measured the main factors which were derived from a fishbone diagram. The measurement system capabilities were analyzed and improved before measurement. Step A analyzed critical problems by examining the process capability and control chart derived from the measured values. Step I analyzed the influence of the main factors on vehicle drift using DOE (design of experiment) to derive the CTQ (critical to quality). The tire conicity and toe angle difference proved to be CTQ. This information enabled the manufacturing process related with the CTQ to be improved. The respective toe angle tolerance for the adjustment process was obtained using the Monte Carlo simulation. Step C verified and controlled the improved results through hypothesis testing and Monte Carlo simulation.

• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.63-72
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• 1998

The stiffness design method is presented as a drift control model of steel structures and applied to design of space trusses subjected to stress and displacement constraints. The stiffness design method is developed by integrating the resizing techniques for an effective drift control algorithm with the strength design process according to the commonly used design specifications such as allowable stress design. In the resizing technique the amount of material to be modified depends on the member displacement participation factors and is determined by an optimization technique. Using the stiffness design method, a structural design model for steel structures is proposed and applied to two verifying examples. As demonstrated in the examples, the displacement of the structures can be effectively controlled without expensive computational cost.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.591-600
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• 2019

Steel tubular buckling controlled braces are well known as being simple, practical and cost-effective lateral force resisting systems. Although these system features have gained the attention of the researchers over the last decade, steel tubular buckling controlled braces currently have limited application. Indeed, only a few steel tubes tightly encased within each other exist in the steel industry. In this paper, a new and practical design method is proposed in order to better promote the widespeared application for current steel tubular buckling controlled brace applications. In order to reach this goal, a holed-adapter made with polyoxymethylene adaptable to all round and square steel sections, was developed to use as infiller. The research program presents designing, producing and displacement controlled cyclic loading tests of a conventional tubular brace and a buckling controlled composite brace. In addition, numerical analysis was carried out to compare the experimental results. As a result of the experimental studies, buckling was controlled up to 0.88 % drift ratio and the energy dissipation capacity of the conventional tubular brace increased 1.46 times due to the proposed design. The main conclusion of this research is that polyoxymethylene is a highly suitable material for the production of steel tubular buckling controlled braces.

• Journal of IKEEE
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• v.11 no.3
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• pp.122-128
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• 2007

Sinusoidal voltage-controlled oscillators (VCOs) based on Colpitts and Hartley oscillators are presented. They consist of a LC parallel-tuned circuit connected in a negative-feedback loop with an OTA-R amplifier and two diode limiters, where the inductor is simulated one realized with temperature-stable linear operational transconductance amplifiers (OTAs) and a grounded capacitor. Prototype VCOs are built with discrete components. The Colpitts VCO exhibits less than 1% nonlinearity in its current-to-frequency transfer characteristic from 4.2 to 21.7 MHz and ${\pm}$95 ppm/$^{\circ}C$ temperature drift of frequency over 0 to $70^{\circ}C$. The total harmonic distortion (THD) is as low as 2.92% with a peak-to-peak amplitude of 0.7 V for a frequency-tuning range of 10.8-32 MHz. The Hartley VCO has the temperature drift and THD of two times higher than those of the Colpitts VCO.

• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.145-152
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• 2010

In this paper, we developed a local oscillator (LO) system of millimeter wave band receiver for radio astronomy observation. We measured the phase and amplitude drift stability of this LO system. The voltage control oscillator (VCO) of this LO system use the 3 mm band Gunn oscillator. We developed the digital phase locked loop (DPLL) module for the LO PLL function that can be computer-controlled. To verify the performance, we measured the output frequency/power and the phase/amplitude drift stability of the developed module and the commercial PLL module, respectively. We show the good performance of the LO system based on the developed PLL module from the measured data analysis. The test results and discussion will be useful tutorial reference to design the LO system for very long baseline interferometry (VLBI) receiver and single dish radio astronomy receiver at the 3 mm frequency band.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.10
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• pp.947-954
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• 2013

This article focuses on a hemispherical resonator gyro driven by the Coriolis effect. The operational principle of resonator gyros and mathematical models are introduced. These models are useful to explain the behavior of a resonator and to design controllers. Several control tests of a resonator have been done. A resonator has been excited by electromagnets controlled by a computer. Its amplitude has been adjusted by a PI control. The transient response is matched with a simulation result based on a mathematical model. A vibrating pattern may drift due to non-uniform factors of a resonator. The drift of the vibrating pattern is controlled and aligned to a reference direction by a PI control. These results are very useful to understand the behavior of resonator gyros and to design advanced control algorithm for better performance.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3230-3232
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• 1999

In this paper describes the design and improvement of a hybrid module for dual slope A/D converter. Since the input voltage to be converted is very sensitive and small. A/D converter must have the temperature stability. low-drift, and the high-resolution the conversion. A dual slop A/D converter circuit which is controlled by microprocessoer has been developed to reduce the offset voltage and the drift characteristics of operation amplifiers, and to improve the A/D conversion speed. Also hybrid module has been adapted to obtain the to obtain the stable and accurate A/D conversion for low cost use. The evaluation of the designed hybrid module has been shown as having a good performance, which will give usefull application to the industrial measurements use.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.43-51
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• 2004

As the slenderness ratio of a high-rise building increases, the lateral load resisting system for the building is more often determined by serviceability design criteria. In serviceability design, the maximum drift and the level of vibration are controlled not to exceed the design criteria. Even though many drift method have been developed in various forms, no practical design method for wind induced vibration has been developed so far. Structural engineers rely upon heuristic or experience in designing wind induced vibration. Development of practical design method for wind induced vibration is required. Generally, wind induced acceleration responses are depending on several variables such as the weight density of a building, damping ratio, the natural period, and etc.. All parameters except the natural period or frequency are usually out of reach for structural engineers, then the wind acceleration response may be proportioned to the natural period. Therefore, in this paper, a wind induced vibration design method based on frequency control technique for high-rise is proposed. The method is applied to vibration design of a 25-story office building for performance evaluation.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.36-36
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• 2002

To Establish of standard technique of length measurent in 2D plane, we develope AFM system. The XY scanner scans the sample only in XY plane, while the Z scanner scans the specimen only in Z-direction. Cantilever tip is controlled to has constant height relative to speciman surface by feedback of PSPD signal. To acquire high accuracy, Z-axis measuring sensor will be added.(COXI or others). In this paper we design XYZ stage suitable for this AEM system. For XY stage, single module parallel-kinnematic flexure stage is used which has high orthogonality and minimum out-of-plane motion. To obtain best performance optimal design is performed. For XY stage, to be robust about parasitic motion optimal design of maximizing Z and tilt stiffness is performed under the constraint of motion range and stage size. And for Z stage, optimal design of maximizing 1st resonant frequency is performed. Because if resonant frequency is get higher, scan speed is improved. So it makes reduce the error by sensor drift. Resultly XYZ stage each have 1st natural frequency of 115㎐, 201㎐, 2.66㎑ and range 109㎛, 110㎛, 12㎛.