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        검색결과 223

        186.
        2013.06 KCI 등재 서비스 종료(열람 제한)
        Lime-bordeaux mixture has been used to prevent diseases in the field of ginseng. The purpose of this study is to investigate the efficacy of lime-bordeaux depending on the concentration and treatment time on major diseases of ginseng such as Alternaria blight and anthracnose, and to evaluate the root growth of ginseng. Lime-bordeaux caused damage on leaf when it was sprayed on ginseng between April and early May. No difference was found in root growth by spraying lime-bordeaux mixture between ratio 4-4 and 8-8 ratio in concentration. Plot of 6-6 raito and 8-8 ratio appeared to be similar efficacy compared to that of practical chemical control. However, the plot of 4-4 ratio showed lower than that of chemical control.
        187.
        2013.05 KCI 등재 서비스 종료(열람 제한)
        In this paper, a high precision outdoor positioning system is newly proposed using multiple GPS receivers based on the Extended Kalman Filter (EKF). Typically, the GPS signal has the instantaneous errors that degrade the positioning seriously. Using the multiple GPS receivers instead of an expensive DGPS receiver, the positioning reliability and accuracy are improved in this research as a low cost solution. To incorporate the small displacement, an INS data have been tightly coupled to the GPS data, which has the inherit disadvantage of the cumulative error occurring over time. To achieve a stabilized and accurate positioning system, the multiple GPS receiver data are fused with the INS data through the EKF process. Through real navigation experiments of an outdoor mobile robot, the performance of the proposed system has been verified to be accurate comparable to DGPS system with a lower cost.
        190.
        2012.08 KCI 등재 서비스 종료(열람 제한)
        The Industrial Ethernet technology enables advanced control architectures and offers several advantages for high precision multiple motors actuation. This paper presents the implementation and analysis of a motor drive with EtherCAT, an industrial standard for real time Ethernet. Considering the characteristics of the implemented software and the network interface, the motion and time-response of motor actuation for the networked Mobile Inverted Pendulum have been analyzed. Using the analysis with the task execution times measured from the developed drive, the performance characteristics of the drive in respect of the maximum achievable throughput have been verified by comparing to the conventional RS232.
        191.
        2012.06 KCI 등재 서비스 종료(열람 제한)
        컨테이너 선사들은 세계경제의 불황과 고유가가 지속되고 있는 상황에서 선박운영비용을 낮추기 위한 다각적인 노력들을 전개하고 있다. 이러한 상황에서, Grand Alliance는 극동 북미서안 서비스인 CCX와 극동 북미동안 서비스인 NCE에 서비스별 선박추가 투입대신에 Dedicated Feeder 투입을 하기로 결정하였다. 즉, 기간항로의 선박이 북중국항만에 기항하지 않고 환적항인 부산항에서 Feeder선을 통하여 환적 운송하게 된다. 본 연구에서는 전용피더 서비스 도입을 통한 환적의 경제성 효과를 확인하기 위하여 Grand Alliance 컨테이너 서비스의 실제 운영 자료에 대해 분석하였다. 이와 같은 전략을 통해 Grand Alliance의 'NCE, 'CCX'항로는 기간항로에 투입되는 선박의 감속운항이 가능하게 되어 선박 운영비의 절감 효과를 보이고 있다.
        192.
        2012.04 KCI 등재 서비스 종료(열람 제한)
        본 연구의 목적은 항만기업 종사자들의 정보보안인식정도와 지각된 정보보안위험 정도에 영향을 미치는 요인들이 어떤 것들이 있는지를 실증 분석하는 것이다. 특히, 지각된 정보보안위험에 영향을 미치는 요인을 파악하기 위하여 위험분석방법론을 토대로 자산, 위협, 취약성과의 관계를 분석하였다. 252개의 유효설문을 대상으로 AMOS를 이용한 구조방정식 모형 분석을 하였다. 연구결과를 보면, 첫째, 항만기업 종사자의 경우 정보자산은 지각된 정보보안위험에 유의하지 않은 결과로 분석되었다. 둘째, 위협, 취약성은 지각된 정보보안위험에 유의한 영향을 미치는 것으로 나타났다. 마지막으로, 정보보안인식과 정보보안교육, 정보보안인식과 정보보안의도와의 관계는 유의하게 분석되었다. 그러나 정보보안관심도는 정보보안인식에 유의하지 않은 것으로 분석되었다.
        193.
        2012.02 KCI 등재 서비스 종료(열람 제한)
        This paper proposes a performance index for the multiple shape object handling of dual arm manipulator to determine whether a robot is good or not. When the dual‐arm manipulator grasps a fixed object and is posed, the dual‐arm manipulator should procure a space to freely control the manipulator. As a performance evaluation parameter, each joint torque from current sensor signal is utilized. From the current information, torque and energy for each joint are estimated. In this paper an performance index for an unstructured object is defined by an energy‐cost function, and stability analysis for each motion is derived by the maximum force to the object. The maximum force to the object is computed by the inertia of object and acceleration information of end‐effector. The acceleration data are derived by the double derivation of each encoder signal. Manipulability measure which implies how efficiently the dual –arm manipulator can move with the grasped object, can be represented by the intersection of the two manipulability ellipsoids for the left and right arms. Effectiveness of the proposed algorithm has been verified through the practical simulations and real experiments.
        194.
        2011.12 KCI 등재 서비스 종료(열람 제한)
        항만물류 전문인력을 양성하기 위한 교육은 항만물류분야의 영역과 그 범위가 매우 광범위하여 국가와 기업이 요구하는 능력을 갖춘 인력을 양성하기란 현실적으로 한계를 보이고 있다. 본 연구는 항만물류 전문인력 양성을 위한 중등교육에 필요한 중요 교과목을 도출하기 위해서 인력 수요 및 공급에 대한 현황 및 예측치를 살펴보고, 국내의 선행연구를 바탕으로 평가모형을 구축하여 교과목의 우선순위를 제시함으로써 의사결정의 판단근거를 제공하는데 목적이 있다.
        196.
        2011.05 KCI 등재 서비스 종료(열람 제한)
        This paper proposes an optimal posture for the task-oriented movement of dual arm manipulator. A stability criterion function which consists of three kinds of feature-representative parameters has been utilized to define the optimal posture. The first parameter is the force which is applied to the object. The torque of each joint and position of arm are attained from the current sensor and encoder, respectively. From these two data, the applied force to an object is estimated using sum of vectors of the joint torques estimated from the measured current. In order to investigate the robustness of each posture, the variation of the end-effector from the encoder information has been utilized as the second parameter. And for the last parameter for the optimality, the total energy consumption has been used. The total consuming energy of each posture can be computed from the current information and the battery voltage. The proposed robot structure consists of a mobile inverted pendulum and dual manipulators. In order to define the optimal posture for the each object, external disturbances are applied to the mobile inverted pendulum robot and the first and second parameters are investigated to find the optimal posture among the pre-selected most representative postures. Finally, the proposed optimal posture has been verified by the proposed stability criterion function which consists of total force to the object, the fluctuation of the end-effector position, and total energy consumption. The effectiveness of the proposed algorithms has been verified and demonstrated through the practical simulations and real experiments.
        197.
        2011.05 KCI 등재 서비스 종료(열람 제한)
        This paper proposes an optimal ARS control of a two-wheel mobile inverted pendulum robot. Conventional researches are highly concentrated on the robust control of a mobile inverted pendulum on the flat ground, i.e., mostly focus on the compensation of gyroscope signals. This newly proposed algorithm deals with a climbing control of a slanted surface based on the dynamic modeling using the conventional structure. During the climbing control of the robot, unexpected disturbance forces are essentially caused by the irregular contact force which comes from the irregular contact angle between the wheel and the terrain. The disturbances have effects on the optimal posture of the mobile robot to compensate the slanted angle. Therefore the dynamics equations through physical interpretation are derived for the selection of optimum climbing posture through ARS. Also using the ultrasonic sensor the slope information is obtained to compensate for the force of gravity. The control inputs are dynamically adjusted to climb up the slanted surface effectively. The proposed algorithm is demonstrated through the real experiments.
        198.
        2010.12 KCI 등재 서비스 종료(열람 제한)
        본 연구는 RIFD를 게이트에 적용하여 활용하고 있는 컨테이너터미널을 대상으로 게이트에서 RFID 수용의도와 적용성과간의 관계를 확인하기 위하여 실증분석을 실시하였다. 먼저, 주요 이론 및 선행연구들을 바탕으로 RFID를 게이트 적용 시에 수용의도에 영향을 미치는 요인으로 기술안정성, 시스템 품질, 보안성 등을 도출하였고, 도출된 요인들 중 RFID 게이트 적용 시 수용의도에 영향을 미치는 요인을 확인하고, RFID 수용의도와 적용성과간의 관계를 설문조사를 통하여 수집된 자료를 바탕으로 가설검정을 실시하였다. 연구결과, 기술 안정성을 제외하고 시스템 품질, 보안성은 RFID 수용의도에 유의한 영향을 미치고, RFID 수용의도는 RFID 적용성과에 유의한 영향을 미치는 것으로 나타났다.
        199.
        2010.11 KCI 등재 서비스 종료(열람 제한)
        This paper proposes an efficient measurement system for the velocity and direction of the wind using the dual rotor wind power generator in vessel. Conventional digital measurement system recognizes the direction and the velocity of the wind using the electric compass or synchronous motor and Vane probe method using hall sensors. But each system has its own short-comings: the synchronous motor has a larger measurement error than the magnetic compass and magnetic compass is weak for the external disturbances such as fluctuation of the vessel. To compensate these short-comings, this paper proposes a new compensation algorithm for the fluctuation errors according to the external interference and the unexpected movement of the vessel along the roll and pitch directions. The proposed system is implemented with the dual compasses and a synchronous motor. The proposed independent power generation system can be operated by itself and can raise the efficiency of the wind power generation systems of 30 ~ 400 W installed along the vertical and horizontal axes. The proposed system also realizes the efficient and reliable power production system by the MPPT algorithm for the real-time recognition of the wind direction and velocity. An advanced switching algorithm for the battery charging system has been also proposed. Effectiveness of the proposed algorithm has been verified through the real experiments and the results are demonstrated.