• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.3
• /
• pp.323-330
• /
• 2016

This paper describes real-time unbalance moment compensation method for line of sight(LOS) stabilization control systems. The factors of system inertia, frictions and unbalance moment affect the control accuracy of drive systems that are equipped to on the move(OTM) platforms requiring LOS stabilization function. In case of the unbalance moment among those factors is continuously changed as variation of relative angle between gravity vector and drive torque vector. Then, consideration of the effect in real-time is very complicate. Therefore, its effect should be designed to be minimized, however, designing it almost zero is impossible in real condition. In other words, it is hard to achieve target performance overcoming stability issue of highly unbalanced systems. To solve these problems, this paper proposes calculation method of unbalance moment by using measured sensor data for LOS stabilization control and its use for control compensation. Also, kinematical converting process and control structure for compensation are explained. The effectiveness of the proposed method as variation of unbalance moment is verified under simulation circumstance modeled by assuming LOS control system with 2-axis gimbal structure.

• The Korean Journal of Health Service Management
• /
• v.10 no.1
• /
• pp.39-51
• /
• 2016

Objectives : This study investigated the health care utilization patterns of workers' compensation insurance(WCI) pneumoconiosis patients with excessively long hospital stays. Methods : The discharge summary data of 3,094 WCI pneumoconiosis patients were analyzed. The study sample was divided into 3 groups based on the length of stay(LOS). Health care utilization patterns were compared among the groups with logistic regression analysis, and the LOS determinants were identified with linear regression analysis. Results : The average LOS of the 222 long stay group patients was 1,448 days. Patients in this group tended to use private general hospitals, were admitted through the emergency room and discharged without the consent of a doctor. Conclusions : Many of the long LOS patients will maintain their inpatient status for the rest of their lives. For quality of life and efficient use of health care resources, policy makers need to establish a policy that enables patients to receive outpatient care in appropriate living conditions outside the hospital.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.1932-1934
• /
• 2001

In this paper, a horizontal LOS(line of sight) rate estimator for conventional sea skimming ASM(anti-ship missile) is proposed. A LOS rate dynamics model in 2 axis gimbal system and in homing geometry is derived. And a new LOS rate estimator is proposed by applying a Kalman filter theory to the LOS rate dynamics model. The proposed filter can estimate LOS rates with taking roll motions into account. Simulation results show the proposed filter produces smaller estimation errors than a conventional method.

• The Korean Journal of Health Service Management
• /
• v.9 no.4
• /
• pp.131-144
• /
• 2015

Objectives : This study investigated the health care utilization patterns and length of stay (LOS) determinants of fracture patients with workers' compensation insurance (WCI) and national health insurance (NHI). Methods : The discharge summary data of 4,394 WCI fracture patients were compared to 28,874 NHI patients. Health care utilization characteristics were compared with a logistic regression analysis, and the LOS determinants were identified with linear regression analysis. Results : The average LOS of the WCI fracture patients was 2.4 times higher than that of the NHI patients. WCI patients used more small or medium sized hospitals, and were more frequently admitted through the emergency room. Females, older patients and patients admitted through emergency room had a significant positive impact on LOS. Conclusions : Healthcare utilization by the WCI fracture patients may include medically unnecessary hospital stays. Therefore, policy makers need to respond appropriately to the inefficient use of health resources by WCI patients.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.10
• /
• pp.951-959
• /
• 2011

In this study, an OTM(on-the-move) antenna which is mounted on ground vehicles and is used for mobile communication between vehicle and satellite while moving was addressed. Since LOS(line-of-sight) of antenna should direct satellite consistently while vehicle moving to guarantee high satellite communication quality, active antenna LOS stabilization is a core technology for OTM antenna. Stabilization of a satellite tracking antenna which consists of 2-DOF gimbals, an elevation gimbal over an azimuth gimbal, was considered in this study. In consideration of driving mechanism which consists of gear train and flexible driving shafts, a two-mass-system dynamic model coupled with vehicle motion was presented. An internal PI-control loop + outer PI-control loop structure has been suggested in order to damp the torsional vibration and stabilize control system. The classical pole-placement method was applied to design control gains. In addition, a vehicle motion compensation control beside of the feedback control loop has been suggested to improve LOS stabilization performances. The feasibility of the proposed control design was verified along with some experimental results.

• Journal of Institute of Control, Robotics and Systems
• /
• v.11 no.4
• /
• pp.363-368
• /
• 2005

This paper proposes an LOS(line-of-sight) guidance system of a ship for path following. From the viewpoint of a control configuration, guidance is a special type of compensation algorithm that is placed in front of the controller to accomplish navigational objects. A guidance system generates a reference trajectory for trajectory tracking or path control and decides the desired velocity, position and heading angle. A control system executes commands based on a reliable guidance law during navigation. An LOS vector from the vessel to a point on the path between two way-points in straight-line navigation or a point among turning circle in turning navigation is selected, and then a heading angle is calculated to converge the desired path based on the LOS vector. The LOS guidance law is defined for the straight-line and the turning circle, respectively. The effectiveness of the suggested LOS guidance system is assured through computer simulation.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.4
• /
• pp.507-512
• /
• 2012

Image blurring in airborne camera can be prevented through timely actuation of LOS(Line of Sight) into the opposite direction to the aircraft advancement, i.e. FMC(Forward motion compensation). Performance verification of FMC requires installation of camera to the aircraft. However, in many ways the verification process has little choice but to be implemented in the laboratory. In this paper verification method of FMC performance in the laboratory is introduced. With collimator target installed in the known reference position image obtained by actual mission plan naturally displays image blurring as well as LOS displacement by FMC effect. Through comparison of the amount of those image blurring and LOS displacement to the equivalent image distortion expected by the application of the FMC reference command can the performance be verified. In this paper we propose a new verification method of FMC performance in laboratory along with generalized solution of FMC reference command, and assess the validity of our proposition.

• Journal of Satellite, Information and Communications
• /
• v.2 no.2
• /
• pp.1-9
• /
• 2007

In this paper, we describe the performance degradation of satellite Wibro system and compensation method in the high-speed railroad channel environment. High-speed railroad channel environment is divided into LOS channel and tunnel. In the LOS channel, signal blocking caused by railroad power feeder structures can be a critical problem which is can be solved with antenna diversity. On the other hand, multi path interference phenomenon, representable by propagation model of Optic Fiber, occurred in the tunnel may be another obstacle. These satellite Wibro system performance degradations in railroad channel environment are addressed and adequate compensation methods are proposed and verified through computer simulation. In addition, the ICI caused by Doppler shift in OFDM system is analyzed with its compensation method.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.11
• /
• pp.881-888
• /
• 2020

In this paper, research on estimation of states of a target of interest using Line Of Sight(LOS) angle measurement is performed. Target's position, velocity, and acceleration are chosen to be the states of interests. The LOS measurement is known to be highly non-linear, making target dynamic modeling hard to be implemented into a filter. To solve this issue, the Pseudomeasurement equation was applied to the LOS measurement equation. With the help of this equation, 3D variable turn target dynamic model is applied to the filter model. For better performance, Kinematic Constraint is also implemented into the filter model. As for the filter, Bias Compensation Pseudomeasurement Filter (BCPMF) is used which is known for its robustness to initial conditions. Moreover, Two-Stage Kalman Filter (TSKF) form was also implemented to benefit from the parallel computation. As a result, TBCPMF 3DVT-KC is proposed and simulated to assess performance.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.10a
• /
• pp.235-236
• /
• 2012