• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.397-407
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• 2017

In this study, a SCR system is employed to selectively reduce $NO_X$, which is a major cause of environmental pollution and issues in diesel engines. In particular, this paper focuses on the combination of feedforward injection strategies, depending on the NO/$NO_X$ ratio, and feedback injection control, using $NH_3$ coverage ratio, based on a SCR model. A 2.2 L passenger diesel engine, which is equipped with a diesel oxidation catalyst (DOC) and a diesel particle filter (DPF), was used in the experiments. The developed control algorithm is implemented on a real-time computer with injection control algorithm. By analyzing the $NO_X$ emission measurement, the performance of the proposed injection control algorithm is verified.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.1
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• pp.116-123
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• 2003

Forages are the most important feed resource for ruminants worldwide, whether fed as pastures, forage crops or conserved hay, silage or haylage. There is large variability in the quality of forages so measurement and prediction of feeding value and nutritive value are essential for high levels of production. Within a commercial animal production system, methods of prediction must be inexpensive and rapid. At least 50% of the variation in feeding value of forages is due to variation in voluntary feed intake. Identification of the factors that constrain voluntary feed intake allows these differences to be managed and exploited in forage selection. Constraints to intake have been predicted using combinations of metabolic and physical factors within the animal while simple measurements such as the energy required to shear the plant material are related to constraints to intake with some plant material. Animals respond to both pre- and post-ingestive feedback signals from forages. Pre-ingestive signals may play a role in intake with signals including taste, odour and texture together with learned aversions to nutrients or toxins (post-ingestive feedback signals). The challenge to forage evaluation is identification of the factors which are most important contributors to these feedback signals. Empirical models incorporating chemical composition are also widely used. The models tend to be useful within the ranges of the datasets used in their development but none can claim to have universal application. Mechanistic models are becoming increasingly complex and sophisticated and incorporate both feed characteristics and use of biochemical pathways within the animal. Improvement in utilisation through the deliberate selection of pasture plants for high feeding value appears to have potential and has been poorly exploited. Use of Near Infrared Reflectance Spectroscopy is a simple method that offers significant potential for the preliminary screening of plants with genetic differences in feeding value. Near Infrared Reflectance Spectroscopy will only be as reliable as the calibration sets from which the equations are generated.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.6
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• pp.68-77
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• 2003

An improved negative capacitance circuit that cancels out input impedance of a front-end in a bioimpedance measurement and operates stably with a low gain margin has been proposed. Since the proposed circuit comprises wide-band operational amplifiers, selecting operational amplifiers is easy, while an operational amplifier of prefer bandwidth should be chosen to apply conventional circuit. Also, since gain margin can be controlled by a feedback resistor connected serially with a feedback capacitor, gain margin is tuneable with a potentiometer. The input impedance of the proposed circuit is two times larger than that of the conventional circuit and 40-times than that without a negative capacitance circuit. Furthermore, closed-loop phase response of the proposed circuit is better than that of the conventional circuit or without a negative capacitance circuit. Above all, for the proposed circuit, the frequency at which a gain peaking occurs is higher than the frequency at which the loop gain becomes a maximum. Thus, the proposed circuit is not affected by a gain peaking and can be operated with a very low gain margin.

• Journal of Information Technology Applications and Management
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• v.14 no.4
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• pp.43-59
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• 2007

The purpose of the study was to examine the effectiveness of Neuro Feedback training by observing the pre and post brainwave measurement results of about 50 (experimental group 25. comparative group 25) subjects who have shown psychological difficulties in studying. attention deficit, and personalities. The study took place at Neuro Feedback training Center B. in between the months of July 2006 and May 2007. The methodology involved in the study included the Coloring Analysis Program of the Brain Quotient Test. As the brain waves are adjusted by timeseries linear analysis. the brain function quotients can reflect the functional states of the brain. Through the test, three parameters relaxation, attention and concentration-were initially measured for one minute each and the lowest parameter out of the three was selected as the training mode or improvement target. The training took place two or three times a week. for about 40 to 60 minutes per session. Because the clients have come to the training center at different times. the researcher sampled the results of only those who had attended more than 30 training sessions. The tool used to measure the psychological reaction was POMS (Profile of Mood State). while the tool used to measure the emotional and attention-deficit characteristics was the Amen Clinic ADD Type questionnaire. Hypothesis testing included t-test. The result of the study showed the Theta: SMR ratio of (left)p = .013. (right) p = .019. The result also confirmed the differences of both ATQ(left) p = .011. (right)p = .030 and SQ(left) p = .017. (right) p = .022. The result confirmed of emotional p = .000. attention-deficit characteristics p = .000. The result of the study suggest Neuro Feedback technique's possibility in positively affecting the subjects' mental state and attention-deficit characteristics.

• Journal of the Korean Magnetics Society
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• v.10 no.5
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• pp.246-249
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• 2000

An Fe$_{49}$ Co$_{49}$ V$_2$alloy is annealed in thermal annealing furnace at 50$0^{\circ}C$, 75$0^{\circ}C$, 80$0^{\circ}C$, and 90$0^{\circ}C$. Annealed samples were cooled in air. The magnetostriction is measured by using a Michelson laser interferometer. Receiving the feedback signal of interference, a mirror attached to piezoelectric transducer (PZT) maintains the optical path length (OPL) between two arms of laser interferometer relatively constant. The feedback voltage is calibrated to the OPL variation. A magnetostriction of 2$\times$10$^{-6}$ at H = 60 Oe increases up to 33.68$\times$10$^{-6}$ at an annealing temperature of 90$0^{\circ}C$, suggesting that the magnetostrictive characteristics are improved by the microstructural modification.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.100-108
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• 2014

Low noise amplifier (LNA) is an integral component of RF receiver and frequently required to operate at wide frequency bands for various wireless system applications. For wideband operation, important performance metrics such as voltage gain, return loss, noise figure and linearity have been carefully investigated and characterized for the proposed LNA. An inductive shunt feedback configuration is successfully employed in the input stage of the proposed LNA which incorporates cascaded networks with a peaking inductor in the buffer stage. Design equations for obtaining low and high impedance-matching frequencies are easily derived, leading to a relatively simple method for circuit implementation. Careful theoretical analysis explains that input impedance can be described in the form of second-order frequency response, where poles and zeros are characterized and utilized for realizing the wideband response. Linearity is significantly improved because the inductor located between the gate and the drain decreases the third-order harmonics at the output. Fabricated in $0.18{\mu}m$ CMOS process, the chip area of this wideband LNA is $0.202mm^2$, including pads. Measurement results illustrate that the input return loss shows less than -7 dB, voltage gain greater than 8 dB, and a little high noise figure around 6-8 dB over 1.5 - 13 GHz. In addition, good linearity (IIP3) of 2.5 dBm is achieved at 8 GHz and 14 mA of current is consumed from a 1.8 V supply.

• Journal of Biomedical Engineering Research
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• v.40 no.6
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• pp.223-229
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• 2019

The number of knee-related disease patients and knee joint surgeries is steadily increasing every year, and for knee rehabilitation training for these knee joint patients, it is necessary to strengthen the muscle of vastus medialis and quadriceps femoris. However, because of the cost and time-consuming difficulties of receiving regular hospital treatment in the course of knee rehabilitation, we developed knee exoskeleton using rapid prototype for knee rehabilitation with feedback from the electromyogram (EMG) and inertia motion unit (IMU) sensor. The modules was built on the basis of EMG and an IMU sensor applied complementary filter, measuring muscle activity in the vastus medialis and the range of joint operation of the knee, and then performing the game based on this measurement. The IMU sensor performed up to 97.2% accuracy in experiments with ten subjects. The functional game contents consisted of an exergaming platform based on EMG and IMU for the real-time monitoring and performance assessment of personalized isometric and isotonic exercises. This study combined EMG and IMU-based functional game with knee rehabilitation training to enable voluntary rehabilitation training by providing immediate feedback to patients through biometric information, thereby enhancing muscle strength efficiency of rehabilitation.

• Smart Structures and Systems
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• v.31 no.3
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• pp.259-273
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• 2023

Real-time hybrid simulation (RTHS) is an effective experimental technique for structural dynamic assessment. However, time delay causes displacement de-synchronization at the interface between the numerical and physical substructures, negatively affecting the accuracy and stability of RTHS. To this end, the authors have proposed a model-based adaptive control strategy with a Kalman filter (MAC-KF). In the proposed method, the time delay is mainly mitigated by a parameterized feedforward controller, which is designed using the discrete inverse model of the control plant and adjusted using the KF based on the displacement command and measurement. A feedback controller is employed to improve the robustness of the controller. The objective of this study is to further validate the power of dealing with a nonlinear control plant and to investigate the potential challenges of the proposed method through actual experiments. In particular, the effect of the order of the feedforward controller on tracking performance was numerically investigated using a nonlinear control plant; a series of actual RTHS of a frame structure equipped with a magnetorheological damper was performed using the proposed method. The findings reveal significant improvement in tracking accuracy, demonstrating that the proposed method effectively suppresses the time delay in RTHS. In addition, the parameters of the control plant are timely updated, indicating that it is feasible to estimate the control plant parameter by KF. The order of the feedforward controller has a limited effect on the control performance of the MAC-KF method, and the feedback controller is beneficial to promote the accuracy of RTHS.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.5
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• pp.867-874
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• 2024

In order to obtain good driving performance in motor control, measurement of the state required for control is necessary. It must also be able to compensate for nonlinear elements of the mathematical model of the motor and disturbances such as load variation. In this study, we design a Kalman filter that can effectively remove noise included in measurements. Kalman filters are effective in estimating the state of linear systems. The system model is feedback linearized by estimating nonlinear terms and load variation as disturbances and compensating them for the system control input. It can be shown that the Kalman filter and the disturbance observer can converge stably independently of each other. As a result of the state estimation, an angular velocity estimation error of within approximately 0.3 [%] and a constant load estimation error of within approximately 4 [%] were obtained.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.85-90
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• 2017

Indoor location-based services have been developed based on the Internet of Things technologies which measure and analyze users who are moving in their daily lives. These various indoor positioning technologies require separate hardware and have several disadvantages, such as a communication protocol which becomes complicated. Based on the fact that a reduction in signal strength occurs according to the distance due to the physical characteristics of the transmitted signal, RSSI technology that uses the received signal strength of the wireless signal used in this paper measures the strength of the transmitted signal and the intensity of the attenuated received signal and then calculates the distance between a transmitter and a receiver, which requires no separate costs and makes to implement simple measurements. It was applied calculating the value for the average RSSI and the RSSI filtering feedback. Filtering is used to reduce the error of the RSSI values that are measured at long distance.It was confirmed that the RSSI values through the average filtering and the RSSI values measured by setting the coefficient value of the feedback filtering to 0.5 were ranged from -61 dBm to - 52.5 dBm, which shows irregular and high values decrease slightly as much as about -2 dBm to -6 dBm as compared to general measurements.