• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.27-33
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• 2009

Human postural responses appeared to have stereotyped modality, such as ankle mode, knee mode and hip mode in response to various perturbations. We examined whether human postural control gain of full-state feedback could be decoupled along with the eigenvector. To verify the model, postural responses subjected to fast backward perturbation were used. Upright posture was modeled as 3-segment inverted pendulum incorporated with feedback control, and joint torques were calculated using inverse dynamics. Postural modalities such as ankle, knee and hip mode were obtained from eigenvectors of biomechanical model. As oppose to the full-state feedback control, independent eigenvector control assumes that modal control input is determined by the linear combination of corresponding modality. We used optimization method to obtain and compare the feedback gains for both independent eigenvector control and full-state feedback control. As a result, we found that simulation result of eigenvector feedback was not competitive in comparison with that of full-state feedback control. This implies that the CNS would make use of full-state body information to generate compensative joint torques.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.961-966
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• 2009

This paper presents precise temperature control of oil outlet in an oil cooler with hot-gas bypass control as an industrial refrigerator. The control system was designed for obtaining precise temperature control performance even though abrupt disturbances based on flow rate control of hot-gas bypass. PID controller was adopted in feedback control system. We showed that the gain of PID could be easily determined by using gain-tuning methods without any numerical model. Through some experiments, excellent control performances such as overshoot within 1.7%, steady state temperature error within ${\pm}0.1^{\circ}C$ were established by a simple PI controller. We expect that the system can control the target temperature within error of $0.33^{\circ}C$ under abrupt disturbances.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.73-80
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• 2000

The stewart platform manipulator proposed by stewart is the parallel manipulator which is composed of several independent actuators connecting the upper plate with the base plate and capable of executing a six degree of freedom motion. The manipulator has a structure of a closed loop form, and provides better load-to-weight ratio and ratio and rigidity than a serial manipulator with an open loop form. Moreover, the manipulator has high positional accuracy because position errors of actuators are not additive. Because of these advantages, this manipulator is widely used in many engineering applications such as a driving simulator, a tool of machining center, a force/torque sensor and so on. When this Stewart platform manipulator is controlled in joint space, it is difficult to design a controller using an analytic method due to nonhnearity and unknown parameters of actuators. Therefore, a PID controller is often used because of easiness in applications. To find the PID control gain, a trial-and-error method is generally used. This method is time-consuming, and does not guarantee a optimal gain. Thus, this paper proposes a GA-PID controller which selects an optimal PID control gain using genetic algorithms. And this proposed controller is evaluated experimentally and shows acceptable performance.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.85-91
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• 2017

This paper concerns the design of a matching module system enabling the RF signal to be harmonized between the new base stations (RRH) and the repeater in the same frequency band of the asynchronous transfer network. This matching system controls the RF Gain Control of the module while monitoring the quality of the quality. Additionally, the RF environment has been adapted accordingly to adjust the RF Gain Control to match the receiver characteristics of the relay. As a result of this study, we improved the quality of the interface between the new base stations and existing relays.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.4
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• pp.276-281
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• 2005

This paper presents a low voltage operating IF QPSK receiver block which is consisted of programmable gain amplifier (PGA) and analog to digital converter. This PGA has 6 bit control and 250MHz bandwidth, $0{\sim}20\;dB$ gain range. Using the proposed PGA architecture (low distortion gain control switch block), we can process the continuous fully differential $0.2{\sim}2.5Vpp$ input/output range and 44MHz carrier with 2 MHz bandwidth signal at 1.8V supply voltage. Using the sub-sampling technique (input freq. is $44{\sim}46MHz$, sampling freq. is 25MHz), we can process the IF QPSK signal ($44{\sim}46MHz$) which is the output of the 6 bit PGA. We can get the SNDR 35dB, which is the result of PGA and ADC at full gain mode. We fabricated the PGA and ADC and the digital signal processing block of the IF QPSK with the 0.18um CMOS MIM process 1.8V Supply.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.10
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• pp.1470-1477
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• 2006

One hundred and sixty crossbred pigs ($6.62{\pm}0.36kg$) weaned at day $18{\pm}1$ were used to investigate the effects of lactitol and tributyrin on performance, small intestinal morphology and enzyme activity. The pigs were assigned to one of five dietary groups (4 pens/diet with 8 pigs/pen) and were fed the negative control diet or the negative control diet supplemented with 10 g/kg glutamine (as a positive control), or 3 g/kg lactitol (${\beta}$-D-galactopyranosyl-($1{\rightarrow}4$)-D-sorbitol), or 5 g/kg tributyrin (butanoic acid 1,2,3-propanetriyl ester), or 3 g/kg lactitol+5 g/kg tributyrin. Body weight and feed intake were measured weekly during the 4-week study. On day 7, four pigs per dietary treatment were sacrificed to examine small intestinal morphology and enzyme activity. The results showed that: (1) Compared with the negative control diet, the positive control diet improved weight gain and feed efficiency during weeks 1-2 and over the entire study (p<0.05), and also decreased duodenal and ileal crypt depth (p<0.05), but did not alter intestinal enzyme activity (p>0.05). Lactitol improved feed efficiency during weeks 3-4 and over the entire study (p<0.05), but did not improve weight gain and feed intake, intestinal morphology or enzyme activity (p>0.05). Tributyrin improved weight gain and reduced feed/gain during weeks 3-4 and over the entire study. Tributyrin significantly decreased crypt depth in the duodenum and ileum, and increased duodenal lactase and ileal maltase activity (p<0.05). Lactitol+tributyrin increased weight gain during weeks 3-4 and over the entire study, and improved feed efficiency during weeks 1-2 and 3-4 and over the entire study (p<0.05). Lactitol+tributyrin increased the jejunal villus height, and decreased the duodenal and ileal crypt depth (p<0.05). Lactitol+tributyrin also increased jejunal lactase and sucrase activity (p<0.05). (2) Compared with the positive control, tributyrin improved weight gain and reduced feed/gain during weeks 3-4 (p<0.05), decreased the ileal crypt depth, and improved the duodenal lactase and sucrase activity (p<0.05). Lactitol+ tributyrin improved weight gain during weeks 3-4, improved feed efficiency during weeks 3-4 and over the entire study, increased the ileal villus height, and increased jejunal lactase, sucrase and maltase activity (p<0.05). These results showed that tributyrin improved performance, intestinal morphology and enzyme activity, while the effect of lactitol was very limited. These results also showed that, compared with glutamine, tributyrin was more effective in improving intestinal morphology and enzyme activity, and tributyrin exerted a superior effect in improving performance as weaning progressed. These observations suggest that, as a chemical for repairing intestinal atrophy, glutamine and tributyrin should be used in the first and second periods of the starter phase, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.892-895
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• 1996

An unknown input observer is proposed that can be used in wheelbase preview control of commercial vehicles. The preview and state information, required to calculate actuator force, are reconstructed from the measurement variables such as heave and pitch acceleration. Gain matrix of observer is optimally selected so that influence of system and measurement noises on the estimation error can be minimized. Estimated preview information requires low pass filtering to eliminate high frequency components resulting from differentiation of noisy output signals. Effectiveness of the proposed method is demonstrated by numerical simulation of half car model.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.382-385
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• 1999

In this paper, by means of Lyapunov second method, the stability of IPD control servo systems is analyzed in the time domain for the first time. Based on the results of the stability analysis, the design rule to select the gain of IPD control is suggested such that the maximum error of output to the nominal system is guaranteed for all uncertainty and load variations. An example of a position control of a brushless dc motor is given to prove the unusefulness of the gain design rule.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.1140-1145
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• 1989

A general dynamic iterative learning control scheme is proposed for a class of nonlinear systems. Relying on stabilizing high-gain feedback loop, it is possible to show the existence of Cauchy sequence of feedforward control input error with iteration numbers, which results in a uniform convergance of system state trajectory to the desired one.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.4
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• pp.439-444
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• 1986

In this paper the PID-B self-tuner[1] is extended to allow a less abrupt response to set point or plant parameter changes and to control a nonminimum phase plant. The proposed extended PID/ST derived from the direct pole-placement PID/ST is obtained with the Bezout identity as the underlying design method. And its control gains are normalized by the integral control gain. Although the integral control gain is normalized to 1 in our scheme, the so-called "set point and derivative kick" can be avoided sufficiently by normalizing the measurement vector and set point.