• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.291-298
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• 2005

Linear acoustic analysis has been performed to elucidate damping characteristics of acoustic cavities. Results have shown that resonant frequencies of acoustic cavity obtained by classical theoretic approach and present linear analysis are somewhat different from each other. This difference is due to the limitation of classical theory. To quantify the damping characteristics, acoustic impedance has been introduced and resultant absorption and conductance have been evaluated. Satisfactory agreement has been achieved with previous experiment. Finally the design procedure for optimal tuning of acoustic cavity has been established

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.25-32
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• 2007

In this paper, a new method for first order plus dead time(FOPDT) model identification is proposed, which can identity multiple points on a process step response in terms of classification of time response. The process input and output to the test are decomposed into the transient part and the steady-state part. The steady-state part express one FOPDT model and the transient part express variously FOPDT model using least square estimation method. The optimum parameter tuning algorithm for PID controller of the Smith Predictor is proposed through ITAE as performance index. The Simulation results show the validity and improvement of performance for various processes.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.8
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• pp.598-608
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• 2002

This paper shows the optimal design methodology for the fluid engine mount by the artificial life algorithm. The design has been commonly modified by trial and error because there is many design parameters that can be varied in order to minimize transmissibility at the desired fundamental resonant and notch frequencies. The application of trial and error method to optimization of the fluid mount is a great work. Many combinations of parameters are possible to give us the desired resonant and notch frequencies, but the question is which combination Provides the lowest resonant peak and notch depth. In this study the enhanced artificial life algorithm is applied to get the desired fundamental resonant and notch frequencies of a fluid mount and to minimize transmissibility at these frequencies. The present hybrid algorithm is the synthesis of and artificial life algorithm with the random tabu (R-tabu) search method. The hybrid algorithm has some advantages, which is not only faster than the conventional artificial life algorithm, but also gives a more accurate solution. In addition, this algorithm can find all globa1 optimum solutions. The results show that the performance of the optimized mount compared with the original mount is improved significantly.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.1-8
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• 2007

Nonlinear acoustic damping of a half-wave acoustic resonator in a rocket combustor is investigated numerically adopting a nonlinear acoustic analysis. First, in a baseline chamber without any resonators, acoustic behavior is investigated over the wide range of acoustic amplitude from 80 dB to 150 dB. Damping factor increases nonlinearly with acoustic amplitude and nonlinearity becomes appreciable at acoustic amplitude above 125 dB. Next, damping effect of a half-wave resonator is investigated. It is found that nonlinear acoustic excitation does not affect optimum tuning condition of the resonator, which is derived from linear acoustics. A half-wave resonator is effective even for acoustic damping of high-amplitude pressure oscillation, but its function of acoustic damper is relatively weakened compared with the case of linear acoustic excitation.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.735-740
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• 2012

In this paper, we introduce design methodologies of polynomial radial basis function neural network classifier with the aid of Principal Component Analysis(PCA) and Linear Discriminant Analysis(LDA). By minimizing the information loss of given data, Feature data is obtained through preprocessing of PCA and LDA and then this data is used as input data of RBFNNs. The hidden layer of RBFNNs is built up by Fuzzy C-Mean(FCM) clustering algorithm instead of receptive fields and linear polynomial function is used as connection weights between hidden and output layer. In order to design optimized classifier, the structural and parametric values such as the number of eigenvectors of PCA and LDA, and fuzzification coefficient of FCM algorithm are optimized by Artificial Bee Colony(ABC) optimization algorithm. The proposed classifier is applied to some machine learning datasets and its result is compared with some other classifiers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.9
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• pp.1138-1143
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• 2020

MRI scans in the abdominal area are difficult to achieve optimal images due to artificial respiration. Among 45 patients (male:female = 30:15) who underwent abdominal MRI examination, a metronome-based examination method was studied for patients whose breathing is difficult and difficult to examine. The images examined without using a metronome were divided into group A, and the images examined using a metronome were divided into group B. Image quality improvement (30%) and inspection time (approximately 50 seconds) were reduced in images using metronome. During abdominal magnetic resonance imaging (ABD MRI), the images examined using a metronome had differences in quality and examination time compared to the unused images. It is more effective to use a metronome brace that controls the patient's respiratory rate during abdominal magnetic resonance imaging under respiratory induction in patients with difficulty in respiratory-gated.

• Journal of the Korean Institute of Telematics and Electronics
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• v.5 no.3
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• pp.9-24
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• 1968

This report is concerned with the optimum design of hyper-aprupt p-n junctiea silion diode and fabriction of this diode usable for electrical tuning application. Impurity profile in the junction was assumed to clean exponential function. With this assunntion, an optimum criterion for designing standard AM radio tuning capacitor was derived. In the diffusion process, after aluminum and antimony as impurties were deposited in vacuum on a P-type silicon wafer, the diffusion was followed by loading the wafer into the high temperature furnace.

• ICROS
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• v.3 no.5
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• pp.38-42
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• 1997

본 고에서는 적응제어의 설계 기법의 연구 현황에 대해 살펴보았다. 매개변수 추정을 기반으로 적응제어기 설계 기법(Estimation-based Design Technique)은 자기동조제어를 시작으로 적응 최적제어 단계를 거쳐, 현재 다변수 적응예측제어로 발전하였고, 이는 화학공정 등 실제 플랜트에 응용될 가능성이 가장 높은 실용적인 설계기법으로 평가받고 있다. 그러나 비선형 시스템에 대한 적용 연구는 활발하지 못한 형편이다. 한편, 안정도 이론을 기반으로 적응 메카니즘을 설계하는 연구는 선형 시스템에 대한 적응제어 연구로 확장되어 현재 활발한 연구가 진행되고 있다. 앞으로 이에 대한 이론 연구가 한동안 지속될 것으로 전망된다. 그러나 이 방법은 실제 시스템에 적용시 적합한 형태로 불확실성을 모델링해야 하며 그 작업은 그리 용이하지 않을 것으로 판단된다. 그러나 부분적으로 이러한 응용연구에 대한 노력이 경주되어야 할 것이다. 비매개변수 추정방법은 적응제어 이론의 주 설계기법은 아니기 때문에 이론으로의 확장 연구는 그리 활발하지 못한 것으로 판단된다. 그러나 비교적 설계방법과 불확실성 모델링이 간단하여 실제 응용에 가장 용이하게 적용될 수 있을 것으로 생각된다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.251-258
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• 2004

This paper presents the parameter study of multiple tuned liquid damper (MTLCD) applied to the 76-story benchmark building. A parameter study involves the effects of number of TLCD, frequency range, and central tuning frequency ratio, which are important parameters of MTLCD. The performance of MTLCD is carried out numerical analysis which reflects the nonlinear property of liquid motion. The parameters of TLCD exist different each optimal values according to mass ratio. The performance of single-TLCD (STLCD) is sensitive for tuning frequency ratio. Therefore, MTLCD is proposed to protect such the shortcoming of STLCD. The result of numerical analysis presents improved performance for robustness of MTLCD

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.104-113
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• 1997

In this paper, the effects of intake manifold systems on volumetric efficiency were investigated in the 4-cylinder 4-stroke cycle diesel engines. The effects of intake manifold system were analyzed on resonant speed and on volumetric efficiency. Resonant speed was calculated by acoustic theory and volumetric efficiency by the method of characteristics. The calculation results agreed well with rest results. It was assured that between the resonant speed and the volumetric efficiency there exists good correlation in multi-cylinder engines. As the results, the prediction of resonant speed was useful to design the optimum intake system. It was assured that the intake manifold systems for BOX-type and RAM-type have different characteristics on the trend of volumetric efficiency. Also a procedure to design the desirable intake manifold system was proposed.