• Korean Journal of Agricultural Science
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• v.37 no.1
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• pp.123-130
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• 2010

A steering control system based on CAN(Controller Area Network) for autonomous tractor was developed to reduce duty of a central processing computer and to improve performance of steering control in terms of reduced control interval and error. The steering control system consisted of a SCU (Steering Control Unit), an EHPS system, and a potentiometer. The SCU consisted of an MCU (Micro Controller unit), an A/D converter, and a DC-DC converter, and a PID controller was used to control steering angle. The steering control system was communicated with the computer by CAN-bus. Each actuator and implement was connected to a multi-function board interfacing with the computer through a USB cable. Without CAN, control interval of the autonomous tractor was 1.5 seconds. When the CAN-based steering control system was combined with the autonomous tractor, however, control interval of the integrated system was reduced to those less than 0.05 seconds. When the autonomous tractor was operated with 1.5-s and 0.05-s control cycles at a 0.63-m/s travelling speed, the trajectories were close to straight lines for both of the control cycles. For a 1.34-m/s traveling speed, tractor trajectory was close to sine wave with a 1.5-s control cycle, but was straight line with a 0.05-s control cycle.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.67-73
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• 2002

The development of high performance HTS wire is a key factor for various electrical applications of coils and cables. The purpose of this paper is to review and consider the main manufacturing technologies of HTS wire and its current status. A lot of efforts have been focused on the optimization of PIT parameters for Bi-2223/Ag wire. According to this, long Bi-2223 wires having Ic of 130 A were recently produced and their mass production has been underway in US. The current status performance of Bi-2223 wire is supposed to be used in power transmission cable because of its lower self-field property. Y-123 second generation conductor is extensively being developed throughout the world and many fabrication processes are competed with each other. 30 m-long Y-123 wire with Ic of 0.8 MA/$\textrm{cm}^2$ was recently fabricated using IBAD and PLD techniques in Japan. This result offers promise of scalable processing of practical multi-layer coated conductor.

• Wind and Structures
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• v.18 no.3
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• pp.235-252
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• 2014

An effective numerical technique to calculate the reactions of a multi-spanned transmission line conductor system, under arbitrary loads varying along the spans, is developed. Such variable loads are generated by High Intensity Wind (HIW) events in the form of tornadoes and downburst. First, a semi-closed form solution is derived to obtain the displacements and the reactions at the ends of each conductor span. The solution accounts for the nonlinearity of the system and the flexibility of the insulators. Second, a numerical scheme to solve the derived closed-form solution is proposed. Two conductor systems are analyzed under loads resulting from HIW events for validation of the proposed technique. Non-linear Finite Element Analyses (FEA) are also conducted for the same two systems. The responses resulting from the technique are shown to be in a very good agreement with those resulting from the FEA, which confirms the technique accuracy. Meanwhile, the semi-closed form technique shows superior efficiency in terms of the required computational time. The saving in computational time has a great advantage in predicting the response of the conductors under HIW events, since this requires a large number of analyses to cover different potential locations and sizes of those localized events.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10C
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• pp.1051-1058
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• 2007

Digital Broadcasting Services get abroad from satellite services to terrestrial services and cable services. As broadcasting services become digital from analog, diverse services such as multi-channel, high quality, time-shift function and so on can be possible. It also generates new digital businesses. The Conditional Access System(CAS) is a technology for providing prevention of illegal access to digital contents. It was applied to digital satellite services at Europe and America from the beginning of 90's. In 2002, a domestic digital satellite service provider adopt a CAS system to their broadcasting services. DRM technologies protect intellectual properties and digital rights of digital contents. This paper suggests a design method to construct a CAS system with DRM which can be applied to a CAS for a small digital broadcasting service.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.2
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• pp.55-60
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• 2002

This paper presents a controller for the multiple DC motors using the CAN(Controller Area Network). The controller has a benefit of reducing the cable connections and making the controller boards compact through the network including expansibility. CAN, among the field buses, is a serial communication methodology which has the physical layer and the data link layer in the ISO's OSI (Open System Interconnect) 7 layered reference model. It provides the user with many powerful features including multi-master functionality and the ability to broadcast / multicast telegrams. When we use a microprocessor chip embedding the CAN function, the system becomes more economical and reliable to react shortly in the data transmission. The controller, we proposed, is composed of two main controllers and a sub controller, which have built with a one-chip microprocessor having CAN function. The sub controller is plugged into the Pentium PC to perform a CAN communication, and connected to the main controllers via the CAN. Main controllers are responsible for controlling two motors respectively. Totally four motors, actuators for the biped robot in our laboratory, are controlled in the experiment. We show that the four motors are controlled properly to actuate the biped robot through the network in real time.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1554-1556
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• 2000

Normal zone propagation(NZP) characteristics were investigated on Ag sheathed multi filamentary Bi-2223 tape and cylindrical stacking conductor. The critical current($I_c$) of Ag sheathed Bi-2223 tape and cylindrical stacking conductor were 12 A, 63 A at 77 K, 0 T. Normal zone propagation(NZP) experiments with tape were conducted with refrigerator in temperature from 45 K to 77 K, 0 T. Cylindrical stacking conductor was molding with epoxy and experiments were conducted with adiabatic condition in $LN_2$. NZP velocities of tape with two condition of DC and AC were almost same at each temperature. Temperature ($T_1$) of tape with distance of 0.5 cm from heater was strongly climbed up to 95K and slowly decreased. NZP velocities of cylindrical stacking conductor were 1.9-2.4 cm/sec in $LN_2$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7C
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• pp.529-533
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• 2008

In this paper, we have analysed the channel loss characteristics of optical fiber due to the changing of radius of curvatures and the number of cable banding, and due to the connection between different modes of fiber to derive revisions of technical regulation for FTTH. The results of test show that all conditions are satisfied the criteria(allowable radius of curvatures, 30mm) with the exception of conditions of 10mm radius in single mode case and show that source of light in multi mode fiber can't be delivered to single mode fiber. henceforth, we should study more intensively on the standards of connection between cables in the different modes.

• Progress in Superconductivity and Cryogenics
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• v.7 no.3
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• pp.39-42
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• 2005

In this paper, the thermal characteristics of multilayer insulation (MLI) were experimentally investigated by using boil-off calorimetry method for seeking optimum standards of thermal insulation conditions. It is necessary to design the thermal insulating efficiency for applying to cryogenic instruments such as HTS power cable system. It is well known that the thermal characteristics and heat transfer of MLI are greatly affected by various MLI structures such as the number of layers and layer density, etc. However, it is difficult to know the thermal characteristics of MLI correctly. The heat leak by MLI between room temperature and liquid nitrogen temperature was measured at various conditions using a cylindrical cryostat. The cryostat consists of two guard vessels located at both end sides and a test vessel between them. The guard vessels are also filled with liquid nitrogen to prevent radiation heat leak through the both end side of the cylindrical test vessel to measure the heat leak only through MLI.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.408-409
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• 2007

Ferrule function have connect Optical Communication Cable. But Ferrule have important role that is decided transmission efficiency and information quality. Key-point of detailed drawing of ferrule is Anti-Reflection. In the study Broadband Anti-Reflection coating Film was design for ferrule of optical connector and deposited in low temperature by Ion-Assisted Deposition system. Optical thin film materials($Ta_2O_5$, $SiO_2$) were manufactured Index and Film thickness. $Ta_2O_5$ index is 2.123 ~ 2.125 and $SiO_2$ is 1.44 ~ 1.442. Reflection Loss of film deposited on Ferrule is 30.1[dB].

• Journal of the Korean Society for Heat Treatment
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• v.4 no.2
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• pp.9-18
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• 1991

Among the many maunfactured processes of producing multi filamentary composites, in situ process is widely used owing tv its simplicity and easyness of mass production. In this study, the mechanical and electromagnetic properties of Cu-Fe composite materials was investigated. The tensile strength of the Cu-Fe wires increased as the Fe content and reduction ratio were increased. The Cu-30 wt%Fe composites had the best properties in terms of figure merits compared to the other Cu-Fe composites made in this study or the commercially manufactured 6/1 ACSR cables of Cu cable. The coercivity was decreased by increasing Fe content, but the squareness was increased greatly. As increasing reduction ratio, the coercivity and squareness increased up to the maximum points, and then decreased. For example, the maximum values were obtained at $0.09mm{\phi}$ for Cu-30 wt%Fe composites and at $0.066mm{\phi}$ for Cu-45 wt%Fe composites. The magnetic property of Cu-Fe wires produced by precipitation treatment was higher than that of Cu-Fe wires produced by thermomechanical treatment. By annealing Cu-Fe wires after drawing process, the coercivity, remanence and squareness were improved.