• International Journal of Automotive Technology
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• v.7 no.5
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• pp.609-618
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• 2006

This paper presents the lateral control of an autonomous vehicle by using a look-ahead sensing system. In look-ahead sensing by an absolute positioning system, a reference lane, constructed by straight lanes or circular lanes, was switched by a segment switching algorithm. To cope with sensor noise and modeling uncertainty, a robust LMI-based $H_{\infty}$ lateral controller was designed by the feedback of lateral offset and yaw angle error at the vehicle look-ahead. In order to verify the safety and the performance of lateral control, a scaled-down vehicle was developed and the location of the vehicle was detected by using an ultrasonic local positioning system. In the mechatronic scaled-down vehicle, the lateral model and parameters are verified and estimated by a J-turn test. For the lane change and reference lane tracking, the lateral controllers are used experimentally. The experimental results show that the $H_{\infty}$ controller is robust and has better performance compared with look-down sensing.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.2
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• pp.95-107
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• 2001

This paper is devoted to the parameter optimization of unmanned aerial vehicle's (UAV) flight control laws. Optimization procedure is based on the ideas of mixed $H_2/H_{\infty}$ control of multi-model plants. By using this approach, some partial $H_2$-terms defining the performance of nominal and parametrically perturbed Flight Control System (FCS) responses to deterministic command signals in stochastic atmosphere as well as $H_{\infty}$-terms defining robustness of the FCS can be incorporated in the composite cost function. Special penalty function imposed on the location of closed-loop system's poles keeps the speed of response and oscillatory properties for both nominal and perturbed FCS in reasonable limits. That is the reason why this procedure may provide reasonable trade-off between the performance and robustness of FCS that are very important especially for UAV. Its practical importance is illustrated by case studies of lateral and longitudinal control of small UAV.

• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.2
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• pp.14-20
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• 2006

A controller design procedure for an electro-hydraulic positioning systems has been developed using $H{\infty}$ control. The generalized plant models and weighting function for multiplicative uncertainty modelling error was presented along with $H{\infty}$ controller designs in order to investigate the robust stability and performance. Both disturbance rejection and command tracking performances were improved with the $H{\infty}$ controller, and the better uniformity of time response is achieved across wide range of operating conditions than the PID, LQR and LQG control scheme. The multiplicative uncertainty case was specifically suited for the design of an electro-hydraulic positioning control systems using $H{\infty}$ control.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.1
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• pp.80-85
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• 2006

Ninety six crossbred pigs (Landrace${\times}$Yorkshire${\times}$Duroc) were used to determine the effects of essential oils (Fresta F $Conc^{(R)}$) supplementation on growth performance, immune response and fecal noxious gas of weaned pigs. Treatments were 1) NC (negative control; basal diet without antibiotics), 2) PC [positive control; basal diet+CSP (CTC+Sulfathiazole+Penicillin) 0.1%], 3) NCF (basal diet+Fresta F $Conc^{(R)}$ 0.03%) and 4) PCF [basal diet+CSP (CTC+Sulfathiazole+Penicillin) 0.1%+Fresta F $Conc^{(R)}$ 0.02%]. From d 0 to 14, ADFI was increased in pigs fed PCF diet (p<0.05). From d 14 to 28, pigs fed PCF diet had greater ADG and ADFI than pigs fed NC diet (p<0.05). From d 28 to 49, ADG and ADFI in pigs fed PCF diet were higher than in pigs fed NC diet (p<0.05). Through the entire experimental period, ADG and ADFI in pigs fed PCF diet were the highest compared to pigs fed NC and PC diets (p<0.05). There was no significant difference in fecal consistency score among the treatments (p>0.05). No statistical differences (p>0.05) were found in red blood cells (RBC) counts, white blood cells (WBC) counts, lymphocyte counts, total protein and albumin. Serum IgG concentration of PCF treatment was greater than that of other treatments (p<0.05). From d 0 to 14, there was no significant difference in digestibility of dry matter and nitrogen among the treatments (p>0.05). From d 14 to 28, digestibility of dry matter in pigs fed PC, NCF and PCF diets was higher than that of pigs fed NC diet (p<0.05) and treatments with added essential oils were higher than other diets on digestibility of nitrogen (p<0.05). Also, from d 28 to 49, digestibility of nitrogen in pigs fed PCF diet was the highest among others (p<0.05). On d 14 and 28, no statistical differences (p>0.05) were found in volatile fatty acid (VFA), ammonia nitrogen ($NH_3$-N) and hydrogen sulfide ($H_2S$) concentrations among treatments. On d 49, there was no significant difference in VFA concentration among the treatments (p>0.05). $NH_3$-N concentration in pigs fed PCF diet was lower than in pigs fed other diets (p<0.05). $H_2S$ concentration in pigs fed diets with added essential oils was lower than others. In conclusion, the results suggest that the dietary addition of essential oils and antibiotics into diets for weanling pigs improved growth performance, IgG concentration and nitrogen digestibility and decreased noxious gas concentration. Essential oils can be used to partly replace antibiotics in diets for weaned pigs without negative affects on growth performance.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.460-465
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• 2019

In this study, the optimization of active materials and the preparation of particulate adsorbents for the application of metal oxide-based adsorbents for the treatment of $H_2S$, an air pollutant and odorant, occurred in various industrial facilities were investigated. The adsorbents were prepared by using $TiO_2$, which has a high physicochemical stability and relatively high specific surface area among metal oxides and also by different kinds and contents of active materials. The correlation between the physicochemical property and adsorption performance of the adsorbents confirmed that the adsorbent containing KI, which is a typical alkali metal among the active metals, showed the highest adsorption performance. The relationship between the contents and the adsorption performance was non-proportional, but a volcano plot. From XRD, SEM and BET analyses, it was confirmed that the active material was exposed to the surface above a certain amount and also the adsorption performance was the best when the specific surface area and pore volume were $40{\sim}100m^2/g$ and $0.1{\sim}0.3cm^3/g$, respectively. For practical application, the adsorbent was granulated or coated on a ceramic support. It was also confirmed that the adsorbent showed high adsorption performance when the adsorbent was coated on the ceramic rather than that of the granulated support.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.221-222
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• 2006

In recent years, the demands of the aspherical glass lenses increase since it is difficult to obtain the desirable performance in the plastic lens. Glass lens is manufactured by the forming with high precision mold core. This paper presents the analysis of optimal grinding condition of tungsten carbide(WC, Co0.5%) using design of experiments(DOE). The process parameters are turbin spindle, work spindle, feedrate and depth of cut. The experiments results are evaluated by MINITAB software.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.1-2
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• 2007

• Journal of the Korea Computer Industry Society
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• v.6 no.3
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• pp.559-566
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• 2005

ALTIBASE is the relational main memory DBMS that enables us to develop the high performance and fault tolerant applications. It guarantees the short and predictable execution time as well as the basic functionality of conventional disk-based DBMS. We present the overview of system architecture and the performance analysis with respect to the various design choices. The assorted experiments are performed under the various environments. The results of TPC-H and Wisconsin benchmark tests are described. We illustrate the various performance comparisons under the various index mechanisms, the replication models, the transaction durabilities, and the application structures. A performance study shows the ALTIBASE system can be applied to the wide area of industrial DBMS fields.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.39-42
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• 2004

Turbo codes, proposed by Berrou, that increase the interleaver size and the number of iteration have better than conventional convolutional codes, in case of BER performance. However, because turbo codes has been required much decoding delay to increase iteration number, it demands unnecessary iterative decoding. Therefore, in this paper, we propose iterative decoding stop criterion that uses the variance of absolute value of LLR. This algorithm can be reduced average iterative decoding number and had lossless performance of BER, because of decreasing unnecessary iterative decoding.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.537-542
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• 2006

This paper deals with the vibration isolation techniques for a large structure using experimental research. In the case of vibration isolation for the vicinity of a subway or a railroad station, most of vibration isolation techniques using isolation materials with high isolation efficiency only, have been applied. Therefore, the quantitative evaluation and design technologies are required for a vibration isolation of large structures. In this study, firstly, vibration characteristics due to train or subway are analyzed. Secondly, the performance of existing vibration isolation materials such as precision isolation material, elastomer is estimated through the experiments. Thirdly the performance of tire isolation material and its frame is tested and evaluated.