• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.538-548
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• 2016

The purpose of this study is to identify the possibility of effective tuning works, understand the characteristics of tuning engine, and analyse the basic data of engine tuning inspection corresponding to the safe operation and environment of a driving gasoline car. The effects of tuning on the characteristics of performance and exhaust emissions under a wide range of engine speeds are experimentally investigated by the actual driving car with a four-cycle, four-cylinder DOHC, turbo-intercooler, water-cooled gasoline engine operating at four types of non-tuning, tuning 1, 2 and 3. The tuning parts in the gasoline engine are the intake manifold, intake pipe and air filter. In the experiment, the output, torque and air-fuel ratio of the five-speed automatic transmission vehicles were measured at the chassis dynamometer(Dynojet 224xLC) with one person on board. The exhaust emissions of $NO_X$, THC, CO, $O_2$ and $CO_2$, and excess air ratio(${\lambda}$) at the other chassis dynamometer(DASAN-MD-ASM-97-KR-HD) were also measured by the idle/constant-speed mode(ASM2525 mode) test method. It is found that the actual air-fuel ratios of non-tuning and tuning engines were shown to be lower than the stoichiometric air-fuel ratio with increasing engine speed, and the actual air-fuel ratio of non-tuning engine was slightly higher than those of tuning engines when the engine speed is more than 4000 rpm. The output was significantly increased by the tuning whereby the maximum output of tuning engine was more increased to approximately 117.64% than that of non-tuning engine. In addition, CO, THC and $NO_X$ emissions of non-tuning and tuning engines measured by the constant-speed test mode were all satisfied with the inspection standards. CO emission was increased, while THC and $NO_X$ emissions were reduced by tuning.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.991-997
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• 2013

A new frequency tuning scheme and a transconductor with a wide tuning range and low harmonic distortion is presented. This frequency tuning technique is based on the relationship between the time-constant and the elapsed times in charging a capacitor up to a certain level. Its structure is as simple as that of a conventional tuning scheme using a VCF(Voltage-Controlled Filter) and it does not need a pure sine wave but uses a CLK(Clock) pulse as a reference signal, which is easily obtained from on-chip system clocks or external X-tal oscillators. When a certain reference CLK is given, without complex capacitor arrays the pole frequency of the filter can be controlled continuously in the frequency domain. Simulation results are presented to confirm the operation of the proposed approach.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.32-36
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• 2003

In this work, we have designed a fully integrated 2.4GHz LC-tuned voltage-controlled oscillator (VCO) with multiple tuning inputs for a 0.25-$\mu\textrm{m}$ standard CMOS process. The design of voltage-controlled oscillator is based on an LC-resonator with a spiral inductor of octagonal type and pMOS-varactors. Only two metal layer have been used in the designed inductor. The frequency tuning is achieved by using parallel pMOS transistors as varactors and back-gate tuned pMOS transistors in an active region. Coarse tuning is achieved by using 3-bit pMOS-varactors and fine tuning is performed by using back-gate tuned pMOS transistors in the active region. When 3-bit digital and analog inputs are applied to the designed circuits, voltage-controlled oscillator shows the tuning feature of frequency range between 2.3 GHz and 2.64 GHz. At the power supply voltage of 2.5 V, phase noise is -128dBc/Hz at 3MHz offset from the carrier. Total power dissipation is 7.5 mW.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.84-90
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• 2010

In this paper, a novel voltage-controlled oscillator (VCO) using the harmonic control circuit based on the composite right/left-handed (CRLH) transmission lines (TLs) is presented to reduce the phase noise without the reduction of the frequency tuning range and miniaturize the circuit size. The phase noise is reduced by the novel harmonic control circuit having the short impedances for the second- and third-harmonic components. The proposed harmonic control circuit is designed by using the CRLH TLs with the dual-band characteristic by the frequency offset and phase slope of the CRLH TLs. The high-Q resonator has been used to reduce the phase noise, but has the problem of the frequency tuning range reduction. However, the frequency tuning range of the proposed VCO has not been reduced because the phase noise has been reduced without the high-Q resonator. The miniaturization of the circuit size is achieved by using the CRLH TLs instead of the conventional right-handed (RH) TLs. The phase noise of VCO is -119.17 ~ -117.50 dBc/Hz at 100 kHz in the tuning range of 5.731 ~ 5.938 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.269-281
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• 2014

In this paper, a systematic design of a low phase noise voltage-tuned dielectric resonator oscillator(VTDRO) using loop group delay is proposed. Designed VTDRO is closed-loop type and consists of a cascade connection of a resonator, phase shifter, and amplifier. Firstly, a reference VTDRO is fabricated and its phase noise and electrical frequency tuning range are measured. Both the phase noise and electrical frequency tuning range depend on the loop group delay. Then, a required value of loop group delay for a new VTDRO with a low phase noise can be systematically computed. In addition, its phase noise and electrical frequency tuning range can be theoretically estimated using those obtained from the measurement of the reference VTDRO. When the loop group delay increases, the phase noise decreases and the electrical frequency tuning range also decreases. The former predominantly depends on the resonator structure. Therefore we propose a systematic design procedure of a resonator with high group delay characteristics. The measured loop group delay of the new VTDRO is about 700 nsec. The measured phase noise of the new VTDRO show a state-of-the-art performance of 154.5 dBc/Hz at 100 kHz frequency offset and electrical frequency tuning range of 448 kHz for a voltage change of 0~10V. The oscillation power is about 4.39 dBm.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1371-1376
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• 2003

In the thermal power plant, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, Strictly maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature, the change of the dynamic characteristics in the reheater. Up to the present time, PID Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on tuning of the 2-DOF PID Controller on the DCS for steam temperature control using immune based multiobjective approach. The stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Therefore tuning technique of multiobjective based on immune network algorithms in this paper can be used effectively in tuning 2-DOF PID controllers.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.260-265
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• 1996

In this paper, we studied effects of active-passive interface on the tuning characteristics of a multielectrode DBR laser. An abrupt interface distorts the threshold gain and the phase change in a multielectrode DBR laser, which results in narrowing of the continuous tuning range. On other hand, an interface with the gradual index change gives tuning characteristics which is very similar to that obtained by ignoring the interface.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.1
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• pp.116-123
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• 2005

The PID controllers have been widely accepted in many industrial systems due to their robust performance in a wide range of operating conditions and their functional simplicity To implement a PID controller, its three parameters must be determined for the given plant. Conventional tuning methods are mainly based on experience and experiment and are lack of systematic procedure Recently. to overcome drawbacks of conventional tuning methods, genetic algorithms have been used, In this paper a real-coded genetic algorithm is employed to search for the optimal parameters of the PID controller for speed control of marine gas turbine engines. Simulation results show the effectiveness of the proposed scheme.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.775-777
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• 1998

The Ziegler-Nichols parameter tuning has been widely known as a fairly heuristic method to good determine setting of PID controllers, for a wide range of common industrial processes. We extract process knowledge required for rule base controller through tuning experiment and simulation study, such as set point weighting and normalised gain and dead time of process. In this paper, we presents a rule base PID controller by extracted process knowledge and the modified Ziegler-Nichols tuning. Computer simulation are provided demonstrate the feasibility of this approach.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.03a
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• pp.43-46
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• 1998

This paper presents a new parameter tuning method for PID controller. The Ziegler-Nichols Parameter tuning has been widely known as a fairly heuristic method to good determine setting of PID controllers, for a wide range of common industrial processes It has a excessive overshoot in the set point response, set point weighting can reduced the overshoot to specified values. It will also be shown that set point weighting is superior to the conventional solution of reducing large overshoot by other method. In this paper, we will modified the Ziegler-Nichols tuning formula by fuzzy set. These method will give appreciable improvement in the performance of PID controllers.