• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.194-201
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• 1998

The beam rotating actuator has been developed. It can be utilized to improve the data transfer rate for the optical disk systems, Newly developed laser beam rotating actuator is applied to put multi-beam spots on more than one track on the optical disk simultaneously. The beam rotating actuator is made of piezoelectric ceramic bimorph as the form of cantilever, Piezoelectric actuators with high resolution, high stiffness and fast frequency response are widely assembled in micropositioning applications. Therefore, the actuator has above 50Hz natural frequency. Beam array is rotated using the dove prism in the end of beamrotator. The dynamic equation of beam rotating actuator is derived theoretically. The actuator is designed on the ground of this analysis. The performance of the beam rotating actuator is verified as the dynamics frequency performance is measured using the dynamic analyzer and sensor.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.712-717
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• 2005

This paper presents a system identification method for multi-input, multi-output (MIMO) systems, by which a rational polynomial transfer function model is identified from experimentally determined frequency response function data. Analytically determined information is incorporated in this method to obtain a more reliable model, even in the frequency range where the excitation energy is limited. To verify the suggested method, shaking table test for an actively controlled two-story, bench-scale building employing an active mass damper is conducted. The results show that the proposed method is quite effective and robust for system identification of MIMO systems.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.432-435
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• 2004

MSC (Multi Spectral Camera) system is a remote sensing payload to obtain high resolution ground image. In this application, uniformity characteristic is important as well as GSD (Ground Resolved Distance) and SNR (Signal to Noise Ratio). MSC image chain is consisted of OM (Optical Module), CCD, Video processor, NUC and DCSU (Data Compression and Storage Unit). Each block makes and corrects MSC's nonuniformity response. This paper shows the cause of nonuniformity error and the correction scheme of MSC system from the electronic point of view.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.71-81
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• 2001

This paper analyzes the effectiveness of minimizing vibration and sound transmission on/through a thin rectangular plate by both feedback control and hybrid control which combines adaptive feedforward control with a feedback loop. An experimental system identification technique using the matrix-fractional curve-fitting of the frequency response data is introduced for complex shaped structures. This identification technique reduces the model order o the MIMO(Multi-Input Multi-Output) system which simplifies the practical implementation. The adaptive feedforward control uses a Multiple filtered-x LMS(Least Mean Square) algorithm and the feedback control uses a multivariable digital LQG(Linear Quadratic Gaussian) algorithm. Experimental results show that an effective reduction of sound transmission is achieved by the hybrid control scheme when both vibration and noise measurement signals are incorporated in the controller.

• International journal of advanced smart convergence
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• v.7 no.2
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• pp.112-118
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• 2018

This paper describes the design and implementation of a vehicle internal alarm system using raspberry-pie and gas sensor. It provides a notification system for sleepiness during driving, a driving time notification system and a smoking detection system. We coded using 'Python'. And we use 'MySQL' and 'PHP' to build the necessary servers and web pages for gathering sensing data and monitoring. The developed system was tested by several methods. All experiments showed satisfactory response signals and detected with immediate responses.

• Journal of the Korean Society of Safety
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• v.24 no.1
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• pp.69-77
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• 2009

This paper reports the aging driver traffic accident severity modeling results. For the modeling, Poisson regression approach is applied using the data set obtained from the Korea Transportation Safety Authority's simulator-based driver aptitude test results. The test items include the estimations of moving objects' speed and stopping distance, drivers' multi-task capability, and kinetic depth perception and so on. The resulting model with the response variable of equivalent property damage only(EPDO) indicated that EPDO is significantly influenced by moving objects' speed estimation and drivers' multi-task capabilities. More interestingly, a comparison with the younger driver model revealed that the degradation of such capabilities may result in severer crashes for older drivers as suggested by the higher estimated parameters for the older driver model.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.4 no.1
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• pp.11-19
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• 2008

Groundwater flow in confined aquifer and heat transport in underground geologic media are using same governing equation(line source) like well fuction. Therefore the conventional slope method using only later data obtained from in-situ thermal response test to determine the thermal conductivity of vertical geothermal heat exchanger(GHEX) is basically identical with one of Theis straight line method of aquifer test under artesian condition. In case that the pumping rate(Q, $m^3$/d) and drawdown(s,m) which are used for input data of existing hydrogeologic computer programs for aquifer test are replaced and converted to supplying heat energy per unit length of bore hole(Q/L,w/m or Kcal/h.m) and temperatures (T,$^{\circ}C$)measured at in and out-let of GHEX as in put data respectively, thermal conductivity around geothermal heat exchanger can be easily estimated without any special modification of the existing hydrogeologic computer program. Two numbers of time series temperature variation data obtained from in situ geothermal response test are analized using Theismethods(standard curve and straight line method) by using existing aquifer test program and conventional Slope method proposed by ASHRAE. The results show that thermal conductivity values estimated by two straight methods are identical and the difference of estimated values between standard curve methods and Slope method are also within acceptable ranges. In general,the thermal conductivity estimated from Theis straight linemethod gives more accurate value than the one of Slope method due to that Slope method uses only visual matching otherwise Theis method uses automatic curve matching estimation with reducing RSS.

• Knowledge Management Research
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• v.21 no.1
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• pp.27-40
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• 2020

Response surface methodology (RSM) empirically studies the relationship between a response variable and input variables in the product or process development phase. The ultimate goal of RSM is to find an optimal condition of the input variables that optimizes (maximizes or minimizes) the response variable. RSM can be seen as a knowledge management tool in terms of creating and utilizing data, information, and knowledge about a product production and service operations. In the field of product or process development, most real-world problems often involve a simultaneous consideration of multiple response variables. This is called a multiple response surface (MRS) problem. Various approaches have been proposed for MRS optimization, which can be classified into loss function approach, priority-based approach, desirability function approach, process capability approach, and probability-based approach. In particular, the loss function approach is divided into univariate and multivariate approaches at large. This paper focuses on the univariate approach. The univariate approach first obtains the mean square error (MSE) for individual response variables. Then, it aggregates the MSE's into a single objective function. It is common to employ the weighted sum or the Tchebycheff metric for aggregation. Finally, it finds an optimal condition of the input variables that minimizes the objective function. When aggregating, the relative weights on the MSE's should be taken into account. However, there are few studies on how to determine the weights systematically. In this study, we propose an interactive procedure to determine the weights through considering a decision maker's preference. The proposed method is illustrated by the 'colloidal gas aphrons' problem, which is a typical MRS problem. We also discuss the extension of the proposed method to the weighted MSE (WMSE).

• The Korean Journal of Applied Statistics
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• v.34 no.4
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• pp.659-669
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• 2021

Multivariate regression often appears in longitudinal or functional data analysis. Since multivariate regression involves multi-dimensional response variables, it is more strongly affected by the so-called curse of dimension that univariate regression. To overcome this issue, Yoo (2018) and Yoo (2019a) proposed three model-based response dimension reduction methodologies. According to various numerical studies in Yoo (2019a), the default method suggested in Yoo (2019a) is least sensitive to the simulated models, but it is not the best one. To release this issue, the paper proposes an selection algorithm by comparing the other two methods with the default one. This approach is called principal selected response reduction. Various simulation studies show that the proposed method provides more accurate estimation results than the default one by Yoo (2019a), and it confirms practical and empirical usefulness of the propose method over the default one by Yoo (2019a).

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.4
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• pp.377-384
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• 2004

Nowadays, control systems consist of smart sensors, smart actuators, and controllers connected via fieldbus. Some devices such as motors in plant environments generate high degrees of EMI or noise. This noise may cause communication errors and make the successful transmission of data longer. Therefore, the noise condition has to be considered at the design of a reliable control system based on a network. This paper presents a scheduling method of task and message to guarantee the given end-to-end constraints under noise environments. A noise model with multi-sources of noise is used, and the analysis method of message's response time is presented when the noise model is applied to CAN (Controller Area Network). Two kinds of noise models are applied to an example system, and the effect to each control loop s end-to-end response time is analyzed. We believe that the proposed method help system designers design the control system guaranteeing its requirements under noise environment.