• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1254-1261
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• 2007

The structure has several types of noise and booming noise of a vehicle is usually caused by the vibration of the vehicle's body transmitted from the engine through the mounting system. Vector synthesis analysis is performed to predict the booming noise when the characteristic of the engine mounting system is changed., i.e., when magnitudes and phases of vibratory forces after the mounts are altered. To use this method effectively, the concept of Multi-dimensional-analysis and Experimental Design are introduced to identify the contributions of each vibration sources and transmission paths to interior noise. It was used 3inputs/1output system and found the magnitudes and phases of the forces for minimizing the noise. Finally, the synthesized interior booming noise level is predicted by the vector synthesis diagram. It is shown that the vector synthesis method can be used to obtain the optimum design characteristic of the mounting system to control the interior booming noise of a vehicle.

• Journal of Power Electronics
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• v.13 no.1
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• pp.59-69
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• 2013

An alternative technique to control multilevel inverters with vector approximations has been presented. The innovative control method utilizes specially designed two-dimensional hysteresis comparators to simplify the implementation and improve the resultant waveform. The multistage inverter designed with maximum number of levels is operated in such a way to approximate the reference voltage vector by exploiting the large number of multilevel inverter vectors. A three-stage inverter with the main high voltage stage made of three phase, six-switch and singly-fed inverter is considered for application to the proposed design. The proposed control concept is to maintain a higher voltage stage state as long as it can lead to a target vector. High and medium voltage stages controllers are based on surface hysteresis comparators to hold the switching state or to perform the necessary change to achieve its reference voltage with minimal switching losses. The low voltage stage controller is designed to approximate the target reference voltage to the nearest inverter vector using the nearest integer rounding and adjustment comparators. Model simulation and prototype test results show that the proposed control technique clearly outperforms the previous control methods.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.36-44
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• 1997

For high performance ac drives, the speed sensorless vector control and the stator flux orientation concept have received increasing attention. This paper describes a speed and flux sensorless vector-controlled induction machine(IM) drive based on the stator flux-oriented control. To improve the accuracy and operating range, the control system employs the previously presented speed and flux estimation methods, and then we present a developed method of estimating the speed of IM. In the proposed method all differential and integral terms have been eliminated by giving a very fast, low-cost, effective and practical alternative to the methods currently available. The effectiveness of the proposed method is verified by simulations and experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.495-499
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• 2000

The booming noise of a vehicle is usually caused by the vibration of the vehicle's body transmitted from the engine through the mounting system. Thus the engine mounting system must be cautiously designed to reduce the noise. Vector synthesis analysis is performed to predict the booming noise when the characteristic of the engine mounting system is changed., i.e., when magnitudes and phases of vibratory forces after the mounts are altered. To effectively use the method, the concept of 'effectiveness' is introduced to identify the contributions of each vibration sources and transmission paths to interior noise. When the magnitudes and phases of the forces due to the engine vibration are changed, the synthesized interior booming noise level is predicted by the vector synthesis diagram. Thus, the optimum characteristics of the forces are obtained through the simulations of the vector synthesis analysis. It is shown that the vector synthesis method can be used to obtain the optimum design characteristic of the mounting system to control the interior booming noise of a vehicle.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.117-124
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• 2021

The development of IOT technology and artificial intelligence technology is promoting the smartization of manufacturing system. In this study, data extracted from acceleration sensor and current sensor were obtained through experiments in the cutting process of SKD11, which is widely used as a material for special mold steel, and the amount of tool wear and product surface roughness were measured. SVR (Support Vector Regression) is applied to predict the roughness of the product surface in real time using the obtained data. SVR, a machine learning technique, is widely used for linear and non-linear prediction using the concept of kernel. In particular, by applying GSVQR (Generalized Support Vector Quantile Regression), overestimation, underestimation, and neutral estimation of product surface roughness are performed and compared. Furthermore, surface roughness is predicted using the linear kernel and the RBF kernel. In terms of accuracy, the results of the RBF kernel are better than those of the linear kernel. Since it is difficult to predict the amount of tool wear in real time, the product surface roughness is predicted with acceleration and current data excluding the amount of tool wear. In terms of accuracy, the results of excluding the amount of tool wear were not significantly different from those including the amount of tool wear.

• Journal of the Korean Association of Geographic Information Studies
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• v.6 no.2
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• pp.46-64
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• 2003

The vector shaped object is generally very long (hundreds or thousands of kilometers) and very narrow (10-100 meters). Image mapping techniques and tools for these objects should be totally different from the traditional area-based targets. Acknowledging these unique characteristics of the vector shaped object, a motion picture mapping system has been developed by combining internet GIS technology with airborne video. In particular, integration between airborne video and digital maps took advantage of each component, and enabled the landscape structure to be visualized, interacted with and deployed all on the Web. The motion picture maps provided a completely new means for disseminating information for area-wide landscape in a visual and interactive manner to the general public while digital map with location information revealed successfully the major parameters that influence an area-wide spatial structure in the study area. The remote video approach breaks down the usual concept of image mapping in a conventional cartography. As a result, the research findings have established the new concept of 'internet airborne video mapping for vector shaped object', proposed as an initial aim of this paper. It would playa crucial role in improving the quality of public information service if the mapping system is operationally introduced into the Government since the highly user-friendly moving picture provides a completely new means for disseminating spatia) information for vector shaped object.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.380-383
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• 2003

In this paper, we propose a fuzzy group decision making method for multiple decision maker-multiple objective programming problems to obtain the agreeable solution. In the proposed method, considering the vague nature of human subjective judgement it is assumed that each of multiple decision makers has a fuzzy goal for each of his/her own objective functions. After eliciting the membership functions from the decision makers for their fuzzy goals, total M-Pareto optimal solution concept is defined in membership spaces in order to deal with multiple decision maker-multiple objective programming problems. For generating a candidate of the agreeable solution which is total M-Pareto optimal, the extended weighted minimax problem is formulated and solved for some weighting vector which is specified by the decision makers in their subjective manner, Given the total M-Pareto optimal solution, each of the derision makers must either be satisfied with the current values of the membership functions, or update his/her weighting vector, However, in general, it seems to be very difficult to find the agreeable solution with which all of the decision makers are satisfied perfectly because of the conflicts between their membership functions. In the proposed method, each of the decision makers is requested to estimate the degree of satisfaction for the candidate of the agreeable solution. Using the estimated values or satisfaction of each of the decision makers, the core concept is desnfied, which is a set of undominated candidates. The interactive algorithm is developed to obtain the agreeable solution which satisfies core conditions.

• Journal of computational fluids engineering
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• v.9 no.2
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• pp.1-10
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• 2004

In the present study, a post-processing program is developed for 3D data visualization and analysis. Because the graphical user interface(GUI) of the program is based on Qt-library while all the graphic rendering is performed with OpenGL library, the program runs on not only MS Windows but also UNU and Linux systems without modifying source code. The structure of the program is designed according to the object-oriented programming(OOP) concept so that it has extensibility, reusability, and easiness compared to those by procedural programming. The program is organized as modules by classes, and these classes are made to function through inheritance and cooperation which is an important and valuable concept of object-oriented programming. The major functions realized so far which include mesh plot, contour plot, vector plot, streamline plot, and boundary plot are demonstrated and the relevant algorithms are described.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.1
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• pp.62-69
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• 2008

A post-processing program based on the OOP(Object-Oriented Programming) concept has been developed for flow visualization of the flow analysis code(PowerCFD) using unstructured cell-centered method. User-friendly GUI(GTaphic User Interface) has been built on the base of MFC(Microsoft Foundation Class). The program is organized as modules by classes including those based on VTK(Visualization ToolKit)-library, and these classes are made to function through inheritance and cooperation which is an important and valuable OOP concept. The major functions of this post-processor program are introduced and demonstrated, which include mesh plot, contour plot, vector plot, surface plots, cut plot, clip plot, xy-plot and streamline plot as well as view manipulation (translation, rotation, scaling etc).

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.4
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• pp.50-59
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• 1992

The paper presents a digital speed control approach of induction motor systems by using a digital servo control method and a well-known second order differential equation as model. The basic concept of using the modeling equation stated in the above is induced from the control theory stand point such that we can describe usually the motor system connected by inverter, generator and load etc, just as a mechanical system to be controlled. The concept does not demand us the complicated vector-based modeling equation adopted in the traditional methods for the speed control of induction motor. Futhermore, the proposed speed control system can be treated as a single input and single output system. The effectiveness of the servo control system obtained by the above-mentioned design concept is illustrated by the experimental results in the presence of both step reference changes and load variations. It is observed from the experimental results that the steady state-error of the experimental set up becomes zero after some regulation time and the induction motor system is robust in spite of reference signal changes and load variations.