Young-Seok Kim

Treatment of intertrochanteric fracture with the Gamma AP locking nail or by a compression hip screw – a randomised prospective trial

Abstract.The Gamma AP (Asia-Pacific) locking nail (GAPN) is a modification of the standard Gamma locking nail made especially for use in Oriental patients. We made a randomised prospective comparison of the compression hip screw (CHS) and the Gamma AP locking nail for the internal fixation of 60 intertrochanteric fractures of the hip in elderly patients by comparing perioperative details and analysing the radiographic and clinical results. The operation time for the GAPN group was shorter than for the CHS group and the intraoperative blood loss was lower. The Gamma AP nail enabled earlier mobilisation. We found no significant difference in the time to union and the length of sliding of the lag screw between the two groups. The decrease in the neck shaft angle in the Gamma nail group was significantly smaller than in the CHS patients. There were no significant mechanical complications, such as fracture of the femoral shaft or failure of fixation in the Gamma nail group. On the basis of our observations we conclude that the Gamma AP locking nail is more efficient than the CHS in the treatment of intertrochanteric fractures in geriatric patients.Résumé.Le clou verrovillé Gamma AP (Asie Pacifique) est la modification du clou Gamma standard pour le morphotype Oriental. Nous avons compare au hasard la compression du col du fémur vissé au clou verrouillé Gamma AP pour la fixation de 60 fractures inter-trochantériennes du col de fémur, en comparant, les details périopératoires, en analysant la radiographie et les résultats cliniques chez des patients agés. La durèe d’opération pour le groupe GAPN était plus courte que pour le groupe CHS, et les pertes sanguines étaient plus faibles dans le groupe GAPN. Le clou Gamma AP favorise l’ambulation plus rapide. Nous n’avons trouvé aucune différence notable de temps de consolidation ni de glissement de la vis entre les deux groupes. La diminution d’angle cervico-diaphysaire dans le groupe clou Gamma était nettement moindre que celle du groupe CHS. Il n’y avait, pas de probléme mécanique grave dans le groupe clou Gamma comme la fracture de diaphyse femorale ou la fixation defailiante. Nous concluons que dans le traitement de la fracture intertrochanterienne de patients agés, le clou verrorillé Gamma AP serait plus efficace que le CHS.

Disturbance observer with binary control theory

This paper is concerned with the chattering reduction of sliding mode control using a disturbance observer based on binary control theory. One of the main causes of chattering is due to the existence of the discontinuous dither term to ensure the robustness with respect to external disturbance. However, the small gain to reduce the chattering causes the robustness to be degraded. In this paper, a disturbance observer based on binary control theory is proposed, and an algorithm which substitutes the discontinuous term with the feedforward compensation using the proposed observer is applied. The validity and the estimation performance of the proposed observer are confirmed through the position control of a permanent magnet synchronous motor.

A speed sensorless vector control for brushless DC motor using binary observer

In this paper, a binary observer with continuous inertial coordinate-operator feedback is proposed to alleviate the chattering phenomenon and enhance the estimation performance in the speed sensorless vector control of brushless DC motors. Binary control consists of a primary loop regulator and an auxiliary loop regulator which smoothly regulates the gain of the primary loop regulator. Substituting a continuous switching input for a discontinuous one, the binary observer has a good estimation performance under the existence of delays and an implementation switching frequency limitation.

Implementation of a speed sensor-less vector control of induction motor by reduced-order extended Kalman filter

The extended Kalman filter (EKF) has been known to be correctly capable of estimating system parameters and state variables by eliminating virtually all influences of structural noise in the field-oriented control scheme for induction motors. This paper presents a design method of a reduced-order extended Kalman filter which consists of rotor speed and flux estimation only by measuring stator currents. The proposed method has some advantages of saving computation time in comparison with the full-order extended Kalman filter. For the noise reduction, robust speed sensorless vector control is realized in the thesis. Experimental results show the effectiveness of the control strategy proposed here for induction motor drives.<<ETX>>

Two-degree-of-freedom speed control of induction motor having two-mass resonant system

This paper examines the speed control of an induction motor system which has a motor and a load connected via a flexible shaft. Such a system often generates shaft torsional vibrations. These vibrations makes it difficult to achieve a fast response to the speed command and may result in damage to the plant. In this paper, a speed control scheme based on two degree-of-freedom control is proposed. The feedback part is designed to suppress torsional vibrations and reject torque disturbances. The feedforward part is also designed to improve the speed response to commands.

Electrolytic capacitor free and reduced 120[Hz] ripple on the output of a single-stage CCM flyback converter with power factor correction for LED lightings

Interest of light emitting diode (LED) lightings is more and more increased because of its low power consumption and long lifetime. Generally, the LED lighting is driven by a power converter. Electrolytic capacitors are used for stabilizing the output ripple of the power converter. However, the expected lifetime of electrolytic capacitors is very shorter than LED or other components in the power converter. As the result of that, expected life time of LED lighting is decreased. In this paper, a single-stage CCM flyback converter without electrolytic capacitors is proposed. The proposed converter is verified through simulations and experiment.

Study of the control technique of the voltage bus conditioner for a DC power distribution system with multiple parallel loads in the electrical vehicle

An electrical vehicle (EV) is a huge issue in the automotive industry. The EV has many electrical units: electric motors, batteries, converters, etc. The DC power distribution system (PDS) is essential for the EV. The DC PDS offers many advantages. However, multiple loads in the DC PDS may affect the severe instability on the DC bus voltage. Therefore, a voltage bus conditioner (VBC) may use the DC PDS. The VBC is used to mitigate the voltage transient on the bus. A suitable control technique should be selected for the VBC. In this paper, PI compensator and sliding mode control (SMC) are designed and compared. The simulation results by PISM simulation package are presented for validating the proposed control techniques.

A Voltage Bus Conditioner with reduced capacitive storage

Distributed Power System (DPS) have many loads with varied functions. In particular, there may be large pulsed loads with short duty ratios which can affect the normal operation of other loads. In this paper, a converter with spilt capacitors and an adaptive controller is proposed as a Voltage Bus Conditioner (VBC) to mitigate the voltage transients on the bus. The proposed converter allows the smaller capacitive storage. In addition, the proposed control approach has the advantage of requiring only one sensor and performing both the functions of mitigating the voltage bus transients and maintaining the level of energy stored. Simulation results by Saber package are presented which verify the control principles and demonstrate the practicality of the approach.

Measurement and Analysis of Light Scattering of Au Pads on PCB Surface to Extract Scattering Parameters

In this study, the influence of surface roughness on light scattering from Au pads on a PCB surface was investigated. Angular distributions of light scattered from Au pads with different surface roughness were measured for several incident angles. Diffusely-scattered light could be separated by using the fact that the amount of specularly-scattered light was directly related to surface roughness. The separated diffuse term was curve-fitted with a physics-based model, and then the related scattering parameters were extracted and compared with measured parameters.

Optimal hysteresis control method for CCM driving of a single-stage PFC flyback converter for LED lightings

Current control of CCM for various converter applications can be implemented by using hysteresis control method which is simple and easy implementation. Hysteresis control band can be generated using the method for multiplying the current reference. In this case, there might be problems that a high switching frequency is generated in the low current section. In this study, in addition to multiplication method, the sum method and the compound method are proposed. This approach can solve the high switching problem in the low current section. Better power factor, THD and efficiency are also expected. The proposed algorithm was verified through simulation and experiments.