• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.167-172
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• 1998

The physical parameters of controlled systems are uncertain and are accompanied with nonlinearity. The transfer function of the controlled system should, therefore, be expressed by interval polynomials. This paper describes the realization of robust performance for that type of control system (interval system) via model reference feedback. First, we will analyze an invariance problem of dynamic characteristics such that the dominant roots do not break away from a specified circular area, and will present a discrimination algorithm (i.e., a division algorithm) for the extreme points of the uncertain coefficients. Then, we will present a design method of control systems which have a robust performance such that the location of the dominant roots dose not vary excessively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.3
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• pp.96-105
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• 1992

The use of fixed-point digital signal processors, such as the TMS 320C25, requires scaling of data at each arithmetic step to prevent overflows while keeping the accuracy. A software which automatizes this process is developed for TMS 320C25. The programmers use a model of a hypothetical floating-point digital signal processor and a floating-point format for data representation. However, the program and data are automatically translated to a fixed-point version by this software. Thus, the execution speed is not sacrificed. A fixed-point variable has a unique binary-point location, which is dependent on the range of the variable. The range is estimated from the floating-point simulation. The number of shifts needed for arithmetic or data transfer step is determined by the binary-points of the variables associated with the operation. A fixed-point code generator is also developed by using the proposed automatic scaling software. This code generator produces floating-point assembly programs from the specifiations of FIR, IIR, and adaptive transversal filters, then floating-point programs are transformed to fixed-point versions by the automatic scaling software.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.709-715
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• 1999

To optimize a heating and cooling system, we need an exact solution lot radiant heat transfer in any form of room or building. This paper describes the solution method of view factor by the area weighted average and graphical method to calculate the radiant heat exchange or daylighting level in any form of room or building. This study shows that the area weighted average and graphical methods have many points of merits(calculation speed, correctness and calculation capability in an arbitrary form of room shapes etc.) compared with existing methods

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.369-372
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• 1998

In this research a fault-tolerant and bumpless switching control is proposed for boiler systems used in the power plants. Firstly, three operating points are selected to control the nonlinear boiler through the full operational range, and the $H_{\infty}$ loop shaping controller and the model-based predictive controller(MBPC) are designed. To prevent the windup and bump problems which are caused by the actuator saturation and the controller switching, an anti-windup and bumpless transfer technique is adopted to the $H_{\infty}$ loop shaping controller. Also the constrained gain-scheduling technique is applied to MBPC to achieve the same objective. Secondly, the fault-tolerant control technique is proposed to continue the control action without stopping the boiler operation even in case of some faults. Through various simulation studies, the performances of the proposed control techniques are demonstrated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.83-88
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• 2004

Acoustic modes of internal region of 4-hp scroll compressor are identified by measuring transfer functions between a reference and 84 measuring points. The corresponding acoustic mode-shapes and natural frequencies were calculated by analysis software SYSNOISE. There exist two clearly distinguishable dipole modes of vertical and horizontal direction and a single quadrupole mode in the frequency region of interest. It shows that the natural frequencies of the identified modes are linearly sensitive to suction pressure (Ps) but relatively in sensitive to discharge pressure (Pd) in operating condition.

• Journal of Korean Association for Spatial Structures
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• v.19 no.3
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• pp.77-83
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• 2019

AU(A plus U-shaped) composite beam was developed for reducing the story height in the residential buildings, and saving the cosrtuction cost of floor structures. Structural performance and economic feasibility of the composite beam have been sufficiently approved through the structural experiments and the analytical studies. Fire safety for the practical application of the composite beam has also been verified through the fire resistance tests and the heat transfer analyses. In this study 2-points bending tests were performed on the four specimens already tested for fire resistance to evaluate the residual bending strength of AU composite beam after fire accident. The same bending test was performed on the one fresh specimen having the same section and span of the specimens for practically comparative study.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.133-142
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• 2014

The least mean square(LMS) algorithm has been popular owing to its simplicity, stability, and availability to implement. But it inherently has a problem of slow convergence speed, and the presence of a transfer function in the secondary path following the adaptive controller and the error path has been shown to generally degrade the stability and the performance of the LMS algorithm in applications of acoustical noise control. In general, in order to solve these problems, the filtered-x LMS (FX-LMS) type algorithms can be used and the bi-directional Filtered-x LMS(BFXLMS) algorithm is very attractive among them, which increase the convergence speed and the performance of the controller with nearly equivalent computation complexity. In this paper, a mathematical analysis for the BFXLMS algorithm is presented. In terms of view points of time domain, frequency domain, and stochastic domain, the characteristics and stabilities of algorithm is accurately analyzed.

• Clinics in Shoulder and Elbow
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• v.1 no.1
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• pp.26-34
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• 1998

The management of acute acromioclavicular dislocations has usually followed the accepted principles of obtaining an anatomical reduction of the joint and maintaining it until soft tissue healing has occurred. So, the preferred treatment for acute acromioclavicular dislocation is controversial. We analysed operatively treated twenty-eight cases for acute acromioclavicular dislocation between February 1994 and January 1997 and reviewed postoperatively to evaluate the results of three different methods. We collected retrospectively the data via clinical history, associated injury, type of injury, radiographic review, Taft score, and final results. Follow up time averaged 14 months. (range, 12 to 21 ) In according to Rockwood's classification, ]7 cases were type Ⅲ, 1 case was type IV, and 10 cases were type V. Ten cases were treated with the modified Phemister method, ten cases with the modified Bosworth method and eight cases with the modified Weaver-Dunn method. ]n patients treated by modified Phemister method, the Taft score was 9.4 points and 8 cases achieved good or excellent results. In patients treated by modified Bosworth method, the Taft score was 9.8 points and 8 cases achieved good or excellent results. In patients treated by modified Weaver-Dunn method, the Taft score was 10.3 points and 7 cases achieved good or excellent results. The overall Taft score was 9.9 points and 23 cases achieved good or excellent results. There were four complications, such as calcification or metallic loosening or breakage of K-wire, but did not influence late results. In conclusions, there was no significant difference of results regarding the different three methods. However, our results indicated that the coracoclavicular ligament reconstruction by transfer of coracoacromial ligament produced better results.

• The Korean Journal of Emergency Medical Services
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• v.13 no.2
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• pp.5-15
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• 2009

Purpose : This study was to examine the secondary traumatic stress(STS) and related factors of emergency medical technicians. Methods : This study was conducted among 190 emergency medical technicians, over the age of 25, with the 1st or 2nd grade qualification, who serve at fire stations in U and P city of Korea. The collected data for this study was analyzed using SPSS 12.0. Result : The average character type of A-type personality technicians was 43.25 points and the average of B-type personality technicians was 37.82 points. It suggested that the former was higher than the latter. State anxiety did not show statistically significant difference between A-Type group and B-Type group with the score of 48.51 for A-Type and 47.91 for B-Type. Physical symptoms showed statistically significant difference between the two groups with the higher score of 28.45 for A-type group than that of 28.13 for B-Type group. The level of STS related to the volunteers' job characteristics was found to be low when the volunteers were satisfied with their job and didn't want to transfer to another division. Those on duty who had slept more than seven hours that day had the highest points. The number of points was highest when the frequency for the onset of trauma was between 20~30 times. Furthermore it was found that for most technicians, 71.05%, the period of symptoms lasted for a few weeks at most, and this was where the STS was the lowest, whereas on the other hand the highest STS occurred when the symptoms lasted for a period of up to six months. The findings showed significant correlations with a relation of r=.24 between STS and level of anxiety and r=.45 between STS and physical symptoms. However, no significant correlation was found between the level of anxiety and physical symptoms. Conclusion : The more emergency medical technicians are exposed to accidents, the more serious the STS are. Those with an A-type personality are especially prone to have higher STS. The higher the STS level is, the higher the level of physical states and anxiety is.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1273-1279
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• 2016

Production of iodine-131 by neutron activation of tellurium in tellurium dioxide ($TeO_2$) material requires a target that meets the safety requirements. In a radiopharmaceutical production unit, a new lid for a can was designed, which permits tight sealing of the target by using tungsten inert gaswelding. The leakage rate of all prepared targets was assessed using a helium mass spectrometer. The accepted leakage rate is ${\leq}10^{-4}mbr.L/s$, according to the approved safety report related to iodine-131 production in the TRIGA Mark II research reactor (TRIGA: Training, Research, Isotopes, General Atomics). To confirm the resistance of the new design to the irradiation conditions in the TRIGA Mark II research reactor's central thimble, a study of heat effect on the sealed targets for 7 hours in an oven was conducted and the leakage rates were evaluated. The results show that the tightness of the targets is ensured up to $600^{\circ}C$ with the appearance of deformations on lids beyond $450^{\circ}C$. The study of heat transfer through the target was conducted by adopting a one-dimensional approximation, under consideration of the three transfer modes-convection, conduction, and radiation. The quantities of heat generated by gamma and neutron heating were calculated by a validated computational model for the neutronic simulation of the TRIGA Mark II research reactor using the Monte Carlo N-Particle transport code. Using the heat transfer equations according to the three modes of heat transfer, the thermal study of I-131 production by irradiation of the target in the central thimble showed that the temperatures of materials do not exceed the corresponding melting points. To validate this new design, several targets have been irradiated in the central thimble according to a preplanned irradiation program, going from4 hours of irradiation at a power level of 0.5MWup to 35 hours (7 h/d for 5 days a week) at 1.5MW. The results showthat the irradiated targets are tight because no iodine-131 was released in the atmosphere of the reactor building and in the reactor cooling water of the primary circuit.