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Quang Vang DANG(Quang Vang DANG ),Viet Thanh Truc TRAN(Viet Thanh Truc TRAN ),Hieu PHAM(Hieu PHAM ),Van Nam MAI(Van Nam MAI ),Quoc Duy VUONG(Quoc Duy VUONG ) 한국유통과학회 2023 The Journal of Asian Finance, Economics and Busine Vol.10 No.2
This paper investigates the determinants of credit accessibility and the effect of credit on the income of farm households borrowing from Vietnam Bank for Agriculture and Rural Development, Giong Rieng District Branch, Kien Giang Province. Based on the primary data of 200 farming households who are the customer of the bank, the study applied the Probit regression model to examine determinant factors of credit accessibility of farm households and employed the Propensity score matching method to investigate the impact of credit on households’ income. The findings of the Probit regression shown that three independent variables that significantly influence the access to credit of households are household size, income source, and farm size. Besides that, the Propensity score matching method results showed a difference of 23.799 million VND/year between the income of borrowing households and that of non-borrowing households at the significance level of 1%. The difference in the imcome from the interval and central matching methods are VND 24.700 million VND/year and VND 24.633 million VND/year, respectively. Given empirical findings suggetsted that several recommendations to increase the credit accessibility of farm households, thereby creating favorable conditions for improving their income.
Adaptive Boundary Control of an Axially Moving String under the Effect of Boundary Disturbance
Quang Hieu Ngo,Quoc Chi Nguyen,Keum-Shik Hong 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, an active vibration control of a tensioned axially moving string under the effect of boundary disturbance is investigated. The dynamics of the translating string are described by a non-linear partial differential equation coupled with an ordinary differential equation. Disturbance estimation at the boundary is performed. A time varying control in the form of right boundary transverse motions is proposed in stabilizing the transverse vibrations of the translating continuum. A control law based on Lyapunov method is derived. Exponential stability of the closed-loop system is verified. The effectiveness of the proposed controller is shown through simulations.
Skew Control of a Container Crane
Quang Hieu Ngo,Keum-Shik Hong,Kyeong Han Kim,Yong Jeong Shin,Sang-Hei Choi 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
This article describes the mathematical model of the 3-dimensional motions of a container crane used in the dockside of a container terminal. The container is suspended by four cables via a spreader. When the container is accelerated or affected by wind, the container will oscillate around horizontal axis (sway) or vertical axis (skew). And an accurate position control of the container is difficult to realize because of uncertain weight, inertial sway, and winds. This paper proposes a simple PID control of the skew motion based on the analysis of 3-dimensional dynamics of the container. This system uses four cylinders to increase and decrease forces in the individual cables so that the container can be affected by yaw torque to reduce the skew error. The simulation results show the effectiveness of the PID controller in controlling the skew motion in the presence of winds.
Skew control of a quay container crane
Quang Hieu Ngo,홍금식 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.12
In this paper, the skew control of the load (container) in the quay crane used in the dockside of a container terminal is investigated. The mathematical model of the 3-dimensional (3D) motions of the load is first derived. The container hooked to a spreader is suspended by four ropes in air. When the container is accelerated by the trolley or is disturbed by winds, it will make a rotational motion (trim, list, and skew) as well as a sway motion in the vertical plane. In such a case, the position of the container becomes difficult to control accurately due to the rotational motion even with the sway motion under control. This paper proposes an input shaping technique for the skew control based on the 3D dynamics of the container. The adopted skew control system uses four electric motors to vary the length of the four ropes individually. Simulation results show the effectiveness of the proposed system in controlling the skew motion.
Orientation Control of a Crane’s Spreader
Quang Hieu Ngo,Yonggyun Yu,Eun Ho Kim,In Gwun Jang,Keum-Shik Hong 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
In this paper, the orientation control (trim, list, and skew control) of the load (container) in the crane located in the mobile harbor (MH) is investigated based on the derived mathematical model of the four-rope crane. A container hooked to a spreader is suspended in air by four ropes. When the container is accelerated by the trolley or is disturbed by winds, it rotates (trim, list, and skew) as well as sways in the vertical plane. When this happens, the accurate positioning of the container becomes difficult because of the rotation even with the swaying under control. This paper proposes a feedback control technique for the orientation control of the container based on the dynamics of the spreader including the container. The adopted control system uses four actuators that vary the lengths of the four ropes, respectively. Experiments are performed with a 1/20 scale MH, in which four snag devices are used, instead of the ball screws as a conventional crane in practice, to vary the rope lengths.
Application of Fuzzy Moving Sliding Surface Approach for Container Cranes
Quang Hieu Ngo,Ngo Phong Nguyen,Quoc Bao Truong,김경한 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2
In this paper, we consider the fuzzy moving sliding surface anti-sway control problem for container cranes. We first introduce the dynamic model of container cranes. Then, we develop the coupled sliding surface which ensures the asymptotic stability of the closed-loop system. Based on the proposed sliding surface, we propose the continuous sliding mode control law which guarantees the reachability of the sliding variable to zero in finite time. Hence, the proposed controller first guarantees the finite-time convergence to the sliding surface and then achieves the stability of the closed-loop system in the predefined sliding surface. Besides, in order to obtain the effective gains for the proposed sliding variable, the fuzzy logic system is employed. To illustrate the efficiency of the proposed control law, simulation results are provided.