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Probabilistic approach for active control of structures: experimental verification
Hwang, Jae-Seung,Min, Kyung-Won,Lee, Sang-Hyun,Kim, Hongjin John Wiley Sons, Ltd. 2005 Earthquake engineering & structural dynamics Vol.34 No.3
<P>In our previous study (Earthquake Engineering and Structural Dynamics 2003; 32:2301), we have developed a probabilistic algorithm for active control of structures. In the probabilistic control algorithm, the control force is determined by the probability that the structural energy exceeds a specified target critical energy, and the direction of a control force is determined by the Lyapunov controller design method. In this paper, an experimental verification of the proposed probabilistic control algorithm is presented. A three-story test structure equipped with an active mass driver (AMD) has been used. The effectiveness of the control algorithm has been examined by exciting the test structure using a sinusoidal signal, a scaled El Centro earthquake and a broadband Gaussian white noise; and, especially, experiments on control have been performed under different conditions to that of system identification in order to prove the stability and robustness of the proposed control algorithm. The experimental results indicate that the probabilistic control algorithm can achieve a significant response reduction under various types of ground excitations even when the modeling error exists. Copyright © 2004 John Wiley & Sons, Ltd.</P>
Osteological Development of the Larvae and Juvenile of Trident Goby, Tridentiger obscurus
Hwang, Seon-Yeong,Park, Jae-Min,Lee, Sung-Hun,Han, Kyeong-Ho The Korean Society of Developmental Biology 2018 발생과 생식 Vol.22 No.3
This study is to observe the developmental process of the larval skeleton according to the growth of the trident goby, Tridentiger obscurus belonging to the larvae and juveniles and use it as the basic data of the taxonomic study. 8 days after hatching, the parasphenoid was ossified with an average total length of 3.62 mm, and basioccipital began to ossify. Caudal vertebrae and neural spine ossified in vertebra. 17 days after hatching, the average total length of the long hairs was 4.32 mm, pterotic and epiotic were ossified, and interhyal and subopercle were ossified. 52 days after hatching, the average total length of the juvenile was 18.2 mm, and lateral ethmoid, hypohyal ossified, vertebrae were parapophysis, and epural bone was osseous to the bone.
Transfer Alignment Design Using a Gyro-free Inertial Navigation System
Jae Hoon Son,Dong-Hwan Hwang,Sang Heon Oh 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.10
The initial value of the inertial navigation system of a launched vehicle can be obtained through the transfer alighnment. If the rotational rate of a moving vehicle exceeds the range of the gyroscope measurements, the angular velocity cannot be measured. Use of the gyroscope with complex structure, large size, more power consumption, and high cost may be avoided. These problems can be resolved by adopting a gyro-free inertial navigation system (GF-INS), which comprises only accelerometers. In the transfer alignment, the slave INS can be configured using a GF-INS. This paper proposes a new type of GF-INS-based transfer alignment design. The configuration of the proposed transfer alignment is presented and an error model of the GF-INS for the Kalman filter is derived. The observability of the proposed method is investigated for a gyro-free inertial measurement unit (GF-IMU) with a cubic structure at level flight with constant velocity and turn maneuver motions. Employing the same GF-IMU undergoing the same motions, the performance of the proposed transfer alignment is also evaluated. As the angular velocity can be measured additionally to the velocity and attitude, angular velocity matchings are also considered in the observability analysis and performance evaluation. It is found that the velocity and attitude measurements should be combined in the matchings of the GF-INS to improve the accuracy of the state estimates.
Sung-hoon Jung,In-cheol Jeon,Ui-jae Hwang,Jun-hee Kim,Oh-yun Kwon 한국전문물리치료학회 2016 한국전문물리치료학회지 Vol.23 No.4
Background: The functioning of the serratus anterior (SA) muscle is essential to normal scapulohumeral rhythm during forward flexion (FF) of the shoulder. Also, SA weakness and overuse of the upper trapezius (UT) is observed in patients with shoulder dysfunction and trapezius myalgia. We designed a combination exercise involving FF and scapular protraction with resistance (CFFSP) to activate the SA muscle and to deactivate the UT muscle. Objects: The purpose of this study was to determine whether or not CFFSP would be more effective in activating the SA muscle than FF alone and FF with scapular protraction (FFP). Methods: Nineteen subjects (12 men and 7 women) participated in this study and performed FF, FFP, and CFFSP at 120°. Surface electromyography was applied to the SA, UT, and pectoralis major (PM) muscles, as was one-way analysis of variance (ANOVA) with repeated measures. Statistical significance was set at .05. Bonferroni adjustment was used to counteract the problem of multiple comparisons, with a statistical level of significance of .017 (.05/3). Results: A statistically significant difference was found in relation to the three positions for the SA muscle (p<.001) and the SA/UT ratio (p=.005) using ANOVA. Significantly different results, depending on the position, were also demonstrated using the Bonferroni post-hoc test for the SA muscle (FF=28.27±16.20, FFP=45.66±15.81, and CFFSP=62.4±27.21) and for the SA/UT ratio (FF=3.04±2.14, FFP=3.61±2.38, and CFFSP=5.95±3.01). Significant differences between the three positions was not found regarding the average amplitude of SA/PM muscle ratio (SA/PM: p=.060). Conclusion: We recommend the use of CFFSP to strengthen the SA muscle at 120°.
Sung-Eun Park,Dae-Young Lee,Jae-Hong Park,Tae-Sik Kang,Jin-Gyoo Yoo,Jungho Hwang IEEE 2009 IEEE transactions on magnetics Vol.45 No.1
<P>With the recent increase of the rotational speed of hard disk drives, nanoparticle contamination can cause serious problems including thermal asperity. We designed a comb-shaped clamp and spacer to improve the efficacy of the recirculation filter in the operation of the hard disk drive (HDD). We calculated flow characteristics by a commercial computational fluid dynamics (CFD) code for six cases of the comb-shaped clamp and spacer. The calculation results showed that the outward velocity was the highest when the comb-shape angle was 45deg. We measured temporal variations of particle concentration during the operation of the HDD by experiments. Considering the decay rate and the percent clean-up of particle concentration, we found the case of 45deg to be the best design.</P>