• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.176.3-176
• /
• 2001

Hydraulic servo system has the characteristic of high power in itself, as combining its characteristics with excellent electro equipment that comes from the development of electronics, electro-hydraulic servo system is widely used in industry that are requested high precision and power Electro-hydraulic servo system is characteristic of very strong non-linearity in itself and it is mainly applied the field of the inner or outer fluctuating load or disturbance in industry. Evolutionary computation based on the natural evolutionary process may solve many engineering problems. Algorithms can represent the natural selection in crossovers, mutations, production of the offspring, selection, etc. Nature has already shown is the superiority through ...

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1430-1433
• /
• 2003

Transducers, which are incorporated in control devices for fixed wing aircraft, land vehicles. and weapon systems were designed and manufactured by use of semiconductor strain gages. These transducers consist of three parts; flange mounts, sensing rods, and semiconductor strain gages. In this investigation, we designed cylindrical sensing rods with high sensitivity and developed installation procedures of semiconductor strain gages. The semiconductor strain gage has hish gage factor such that it can produce high resistance change in spite of low strain, but it is so small and fragile that one should handle carefully and sophisticated installation method is needed for good performances. The prototype transducers are manufactured, and then tested about three important factors: sensitivity, linearity, and hysteresis. We got results or 0.084 V/N sensitivity, 0.2% nonlinearity, and 0.5% hysteresis.

• Journal of the Korean Chemical Society
• /
• v.7 no.4
• /
• pp.288-292
• /
• 1963

The rates of reaction of various Korean anthracites with carbon dioxide were measured at temperatures ranging from $850^{\circ}C$ to $1100^{\circ}C$ with coal -6, +8 sieve size and the residence time of reactant gas in the fixed coal bed 14.0 to 15.0 seconds. The primary variables studied were the coal sources and temperature. The reactivity was considerably varies with the coal sources and the general trends show that the reactivity sharply increases with increasing reaction temperature except the Yongwol coal where the increase is not so sharp, which is considered to be due to high reactivity and high-pore structure of the coal. It was also found that a straight line was produced when a logarithm of the rate constant is plotted against the reciprocal of the absolute temperature up to 1000^${\circ}C$, but above that temperature it deviates from linearity. The information obtained will be of value in the design of the coal gasifier using Korean anthracites.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.3
• /
• pp.189-194
• /
• 2001

This paper presents a mew design of an inductive position sensing system with high sensitivity. The designed system consists of the driving coils, position-detecting coils, and closed loop formed magnetic blocks. To obtain high sensitivity we design a symmetric and closed loop type measuring system with small air-gaps. The elements that affect the system characteristics are turn ratio, excitation frequency, air-gap size, capacitance effect, and load resistance. By experimental investigation, the influences of these elements are examined and the system parameters are selected. The sensitivity of the newly designed system is greater than 2800mV/(V mm) and the linearity error is below${\pm}0.01%; in; the; range; of; {\pm}200{\mu}m$.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.587-592
• /
• 2000

As the residential spaces become high-rised and high-density, Multi-story buildings were constructed with transfer girders, Deep beams, wall foundations, floor diaphragms an shear walls which may have column offsets. Especially, In the analysis and design of Multi-story buildings, the lateral loads must be taken into account. But, there have been no appropriate theory and national design code for predicting ultimate shear strength of reinforced concrete Deep beams with web opening. Only empirical and semi-empirical formulas for predicting their ultimate load bearing capacities due to the complexities of the structural non-linearity and material heterogeneity. So this study analyze tow-dimensional finite element model that represents exactly the behavior of real structures with SBETA which are general nonlinear finite element analysis program, and compare the results with that from the real reinforced Concrete Deep beams with web opening tests. From the comparison, and parametric study, The Study presents the elementary data of the earthquake resistance for the reinforced concrete Deep beams with web opening.

• Proceedings of the IEEK Conference
• /
• 2002.06e
• /
• pp.47-50
• /
• 2002

An extended-counting analog to digital converter (ADC) is designed to have a high resolution(14bit) with low power consumption and small dia area. First order sigma-delta modulator with a simple counter for incremental operation eliminates the need of big decimation filter in conventional sigma-delta type ADC. To improve the accuracy and linearity, extended mode of successive approximation is followed. For 14-bit conversion operation, total 263 clocks(1 clock for reset, 256 clocks for incremental operation and extended 6 clocks for successive approximation operation) are needed with the sampling rate of 10 Ms/s This ADC is implemented in a 0.6um standard CMOS technology with a die area of 1 mm ${\times}$ 0.75 mm.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.649-659
• /
• 2003

OFDM/FH communication system Is widely used in the wireless communication for the large capacity and high-speed data transmission. However, phase noise and PAPR (peak-to-average power ratio) are the serious problems causing performance impairment. In this paper, PLL (phase locked loop) frequency synthesizer with high switching speed is used for the phase noise model. SSPA and TWTA are considered for the nonlinear HPA model. Under these conditions and by approximating $e^{j{\phi}[m]}$ into $1 + j{\phi}[m]-\frac{1}{2}{\phi}^2[m]$ for the phase noise nonlinear approximation, SINR (signal-to-interference-noise-ratio) with nonlinear HPA and phase noise is derived in the OFDM/FH system. The bit error probabilities (BER) are found by computer simulation method and semi-analytical method. The simulation results closely match with the semi-analytical results.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 1999.11a
• /
• pp.327-329
• /
• 1999

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.86-89
• /
• 1994

This paper describes the fabrication and basic characteristics of a Si Hall device fabricated on a SOI(Si-on-insulator) structure. In which SOI structure was formed by SOB(Si-wafer direct bonding) technology and the insulator of the SOI structure was used as the dielectrical isolation layer of a Hall device. The Hall voltage and sensitivity of the implemented SDB SOI Hall devices showed good linearity with respectivity to the applied magnetic flux density and supple iud current. The product sensitivity of the SDB SOI Hall device was average 670 V/A$.$T and its value has been increased up to 3 times compared to that of bulk Si with buried layer of 10$\mu\textrm{m}$. Moreover, this device can be used at high-temperature, high-radiation and in corrosive environments.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.6
• /
• pp.128-135
• /
• 1996

This paper proposes a high precision measurement technique to obtain the height of gage block with a few millimeter height. The proposed technique is consisted of two steps : In the first step, laser position transducer and electric micrometer are adopted to obtain a coarse value of the height of gage block, and then, in the second step, heterodyne laser interferometry is adopted to acquire the precision value. A new kind of phase detector is constructed in the low cost for the heterodyne interferometer and its linearity with ${\pm}1%$ is confirmed by experiment. Also measurement error factors due to enviroments are discussed and methodology to reduce such errors is proposed. Preliminary experiments are carried out for the gage blocks of as high as a few millimeter.