• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
• /
• pp.158-161
• /
• 1995

A new laser diode range-finding speedometer is proposed, which is modulated by a pair of positive and negative triangular pulse current superimposed on a dc current. Since a target velocity is directly obtained form a pure Doppler beat frequency measured during the non-modulation period, the new sensor is free from the difficulties due to the critical velocity encountered in the previous sensor. Furthermore, the different amplitude of the two triangular pluses are so adjusted that the measurable range using only one laser head is greatly expanded to 10cm through 150cm, which is about two times that of the previous sensor. The measurement accuracy for velocity of .+-.6mm/s through .+-.20mm/s and for range is about 1%, and 2%, respectively. Because the new sensor can be operated automatically using a microcomputer, it will be useful for application of a 3-D range image measurement of a slowly moving object.

• 센서학회지
• /
• 제21권1호
• /
• pp.1-6
• /
• 2012

Using a current-mode multiple reset, a current-to-voltage(I-V) converter with a wide dynamic range was produced. The converter consists of a trans-impedance amplifier(TIA), an analog-to-digital converter(ADC), and an N-bit counter. The digital output of the I-V converter is composed of higher N bits and lower bits, obtained from the N-bit counter and the ADC, respectively. For an input current that has departed from the linear region of the TIA, the counter increases its digital output, this determines a reset current which is subtracted from the input current of the I-V converter. This current-mode reset is repeated until the input current of the TIA lies in the linear region. This I-V converter is realized using 0.35 ${\mu}m$ LSI technology. It is shown that the proposed I-V converter can increase the maximum input current by a factor of $2^N$ and widen the dynamic range by $6^N$. Additionally, the I-V converter is successfully applied to a photometric sensor.

• ETRI Journal
• /
• 제38권5호
• /
• pp.858-867
• /
• 2016

A high dynamic range (HDR) video service is an upcoming issue in the broadcasting industry. For compatibility with legacy devices receiving a non-constant luminance (NCL) signal, new tools supporting an HDR video service are required. The current pre-processing chain of HDR video can produce color noise owing to the chroma component down-sampling process for video encoding. Although a luma adjustment method has been proposed to solve this problem, some disadvantages still remain. In this paper, we present an adaptive color noise reduction method for an NCL signal of an HDR video service. The proposed method adjusts the luma component of an NCL signal adaptively according to the information of the luma component from a constant luminance signal and the level of color saturation. Experiment results show that the color noise problem is resolved by applying our proposed method. In addition, the speed of the pre-processing is increased more than two-fold compared to a previous method.

• 센서학회지
• /
• 제24권2호
• /
• pp.79-82
• /
• 2015

This paper proposes a novel complementary metal oxide semiconductor (CMOS) active pixel sensor (APS) and presents its performance characteristics. The proposed APS exhibits a linear-logarithmic response, which is simulated using a standard $0.35-{\mu}m$ CMOS process. To maintain high sensitivity and improve the dynamic range (DR) of the proposed APS at low and high-intensity light, respectively, two additional nMOSFETs are integrated into the structure of the proposed APS, along with a photogate. The applied photogate voltage reduces the sensitivity of the proposed APS in the linear response regime. Thus, the conversion gain of the proposed APS changes from high to low owing to the addition of the capacitance of the photogate to that of the sensing node. Under high-intensity light, the integrated MOSFETs serve as voltage-light dependent active loads and are responsible for logarithmic compression. The DR of the proposed APS can be improved on the basis of the logarithmic response. Furthermore, the reference voltages enable the tuning of the sensitivity of the photodetector, as well as the DR of the APS.

• 대한산업공학회지
• /
• 제39권5호
• /
• pp.351-360
• /
• 2013

Taguchi's robust design is a method for quality improvement by making a system insensitive to uncontrollable variations incurred by noise factors and it has received much attention in a wide range of engineering fields. Robust design can be broadly classified into static and dynamic ones. This paper is concerned with dynamic robust design. Taguchi suggested to use a signal-to-noise ratio as a robustness measure, but there has been much debate and criticism on its blind use. In order to cope with this drawback, many alternatives have been proposed. They are divided into performance measure modeling (PMM) and response function modeling (RFM) approaches. In this paper, both PMM and RFM approaches for dynamic robust design are reviewed. An example for illustration is provided as well.

• Structural Engineering and Mechanics
• /
• 제91권3호
• /
• pp.325-334
• /
• 2024

This paper deals with the dynamic buckling behavior of truncated conical shells composed of carbon nanotube composites, an important area of study in view of their very wide engineering applications in aerospace industries. In this regard, the effective material properties of the nanocomposite have been computed using the Mori-Tanaka model, which has already been established for such analyses. The motion equations ruling the structure's behavior are derived using first order shear deformation theory, Hamilton's principle, and energy method. This will provide adequate background information on its dynamic response. In an effort to probe the dynamic instability region of the structure, differential quadrature method combined with Bolotin's method will be adopted to tackle the resulting motion equations, which enables efficient and accurate analysis. This work considers the effect of various parameters in the geometrical parameters and the volume fraction of CNTs on the structure's DIR. Specifically, it became clear that increasing the volume fraction of CNTs shifted the frequency range of the DIR to higher values, indicating the significant role of nanocomposite composition regarding structure stability.

• Journal of Power Electronics
• /
• 제9권4호
• /
• pp.582-592
• /
• 2009

This paper proposes a new speed sensorless direct torque and flux controlled interior permanent magnet synchronous motor (IPMSM) drive. Closed-loop control of both the torque and stator flux linkage are achieved by using two proportional-integral (PI) controllers. The reference voltage vectors are generated by a SVM unit. The drive uses an adaptive sliding mode observer for joint stator flux and rotor speed estimation. Global asymptotic stability of the observer is achieved via Lyapunov analysis. At low speeds, the observer is combined with the high frequency signal injection technique for stable operation down to standstill. Hence, the sensorless drive is capable of exhibiting high dynamic and steady-state performances over a wide speed range. The operating range of the direct torque and flux controlled (DTFC) drive is extended into the high speed region by incorporating field weakening. Experimental results confirm the effectiveness of the proposed method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 D
• /
• pp.2408-2410
• /
• 2001

This paper presents the control of an underactuated two-link robot called the Pendubot. Combining linearized state feedback control with Takagi-Sugeno(T-S) fuzzy controller wide-range stabilization of Pendulum is achieved. The local stabilization controler is designed by linearinzing the dynamic equations about the several desired set point and using LQR(Linear Quadratic Regulator) techniques. Takagi-Sugeno methodology is used to control the nonlinear models near different operation points. Fuzzy controller is obtained by the fuzzy blending of the local controllers. The paper includes a description of the algorithm as well as real time experimental results for the Pendubot.

• 한국음향학회:학술대회논문집
• /
• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
• /
• pp.867-872
• /
• 1994

The transfer function of an acoustic system, in general, often exhibits a wide dynamic range and a very long impulse response. The time-stretched pulse (TSP) proposed by Aoshima (ATSP) has a small peak-factor and is accordingly suitable for the measuring impulse responses. The pulse is not so suitable, however, for the measurement of impulse responses over a wide frequency range. In this paper, we try to generalize and optimize this method (OATSP). This makes the method applicable for measuring of impulse responses longer than the length of the TSP. An analysis of error in such a case is also shown. Finally, we discuss how to implement this technique in specific measurement conditins.

• Journal of the Korean Wood Science and Technology
• /
• 제27권2호
• /
• pp.15-22
• /
• 1999

진동 충격음 흡수성능을 지니는 샌드위치구조 목질 복합재료 제조용 폴리머는 넓은 온도범위(또는 주파수 범위)에서 높은 손실계수를 지니면서, 동시에 $5{\times}10^7\sim-10^9\;dyne/cm^2$의 탄성율을 지녀야 한다. 본실험에서는 이러한 점탄성 거동율 나타내는 고분자재료의 제조를 목적으로 에폭시 수지/아크릴 수지 상호침투망목고분자(IPNs)를 동시망목형성법으로 합성하였다. 고분자의 동적 점탄성은 Rheovibron을 사용하여 110Hz에서 측정하였으며, 복합체의 손실계수 및 동탄성 계수는 Rheovibron을 개조한 양단지지 강제 휨 진동법으로 주파수 110Hz에서 측정하였다. 동력학적 측정 결과, 손실탄성율의 최대값 온도 및 손실계수의 최대값 온도가 이동하고, 유리전이 영역이 확대되어, 이 IPNs계는 부분 상용계임을 알 수 있었다. 특히, 70/30 및 50/50 조성의 Epikote871/P(n-BMA) IPNs는 넓은 온도 범위에서 비교적 높은 손실계수 및 적당한 탄성율을 나타냈다. 또한 이를 적층한 목질 복합체는 넓은 온도 범위에서 비교적 높은 진동흡수 계수를 나타냈다.