• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.23-26
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• 2014

This paper represents the detection method of voltage disturbance for high temperature superconducting (HTS) tape using electromagnetically coupled coils. In order to detect the voltage as the superconductor transits from the superconducting state to the normal conduction state, voltage taps are widely used to get the voltage signal. And voltage taps are connected to data acquisition device via signal wires. However this new suggested method can detect the superconducting transition voltage without signal wires between voltage taps and data acquisition device by using electromagnetically coupled coils. This system consists of two electromagnetically coupled coils, the first coil to detect and transmit the voltage of HTS tape and the second coil to pick up the transmitted voltage from the first coil. By using this new suggested method, we can build the 'separated voltage-detection system'. HTS tape and first coil are located under liquid nitrogen vessel and the second coil is located under room temperature condition. In this paper, experiments are performed to verify the feasibility of the proposed method. As the result of the experiment, the separated voltage-detection system using electromagnetically coupled coils can successfully observe superconducting-normal transition of HTS tapes.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.123-129
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• 2017

In this paper, we proposed a smart multiple-tap system which a remote user with smartphone can control multiple-taps in order to reduce standby-power consumption more conveniently when plugged-in electric appliances are turned-off. Recently, several researches of smart multiple-tap using IoT technology has reported. However, in these researches, an additional device like as a server computer is necessary, or multiple-taps could be only remotely controlled by smartphone and not directly controlled by on/off switch. The proposed smart multiple-tap system does not need any additional device only if it has a WiFi router, and it can be used for user as well as remote control using smartphone application and physically direct control using contact switches like existing multiple-taps. Our approach is to develop a smart multiple-tap device capable of WiFi communication can each serve as a server or a client, and can be operated by the hybrid switch combining the on/off contact switch and the relay switch. We implemented the prototype of the proposed system composed of the smart multiple-tap device and the smartphone application, and the test of the prototype validates the proposed system.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1125-1128
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• 1998

A new architecture for high-speed implementation of adaptive decision-feedback equalizer (ADFE) applicable to wide-band digital wireless modems is described. Rather than using conventional two's complement arithmetic, a novel complex-valued filter structure is devised, which is based on redundant binary (RB) arithmetic. The proposed RB complex-valued filter reduces the critical path delay of ADFE, as well as leads to a more compact implementation than conventional methods. Also, the carry-propagation free (CPF) operation of the RB arithmetic enhances its speed. To demonstrate the proposed method, a prototype chip set is designed. They are designed to contain two complexvalued filter taps along with their coefficient updating circuits, and can be cascaded to implement loger filter taps for high bit-rate applications.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.524-526
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• 2005

As a research activity of the project of "Verification Test of Superconducting Power Cable", we measured the AC loss of a short length superconducting power cable. The rating and the length of the cable were 22.9kV, 1,250A and 2.2m. The voltage taps for measuring the AC loss were attached to both ends of the conductor of the superconducting cable. Through the voltage taps and a lock-in amplifier we measured the in-phase component of the voltage($V_x$) with the load current(I). The AC loss was measured by multiplying the in-phase component of the voltage($V_x$) by the load current(I). The value of the AC loss of the superconducting power cable was 1.18W/m/phase/kA at 77.3K, 1atm.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.507-509
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• 1989

In multiple current source inverter, generally, transformer connection method and direct connection method in output side have been used. But these methods have faults such as the increment of the number of inverter and the need of the transformer for changing phase in order to get above 12 phase. In this system, we obtained the output currents of 24 phase by adding 2taps in 12 phase inverter. Therefore, this system has such characteristics as the miniaturization of devices and the simplicity of control signal by controlling two inverters and two SCRs for changing taps.

• The KSFM Journal of Fluid Machinery
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• v.9 no.3 s.36
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• pp.22-28
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• 2006

The discharge coefficient in segmental wedge haying ninety degrees yeller angle for the five kinds of opening ratio with differential pressure taps located at both upstream and downstream of one diameter of pipe was measured. Main purpose of this work is placed on specifying the characteristic of discharge coefficient of a segmental wedge used as a primary element of flow metering devices, and suggestion for the fixed location of pressure taps useful. Although the range of the opening ratio over this work is more expanded than previous studies. The opening ratios of segmental wedge, namely 0.3, 0.4, 0.5, 0.6 and 0.7 were investigated. The Reynolds number based on the spool inside diameter ranges from 12,000 to 380,000.

• Wind and Structures
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• v.13 no.3
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• pp.257-273
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• 2010

The aerodynamic and aero-elastic model tests of the China''s highest cooling tower has been carried out in the TJ-3 Boundary Layer Wind Tunnel of Tongji University. By adopting a scanivalve system, the external wind pressure is firstly measured on $12{\times}36$ taps for a single tower, two and four grouped towers under the condition of both smooth flow and the boundary layer due to surrounding geographic and building topography. The measurements of internal wind pressure distribution of $6{\times}36$ taps are taken for a single tower under the various ventilation ratios ranging from 0% to 100% of stuffing layers located at the bottom of the tower. In the last stage, the wind tunnel tests with an aero-elastic model are carefully conducted to determine wind-induced displacements at six levels (each with eight points) with laser displacement sensors. According to the measurement results of wind pressure or vibration response, the extreme aerodynamic loading values of the single or grouped towers are accordingly analyzed based on probability correlation technique.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.1
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• pp.25-32
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• 1988

In this paper, a new method for reducing harmonics in input AC line currents of converter is presented, which is due mainly to the equipment of 2-4 switching taps on interphase reactor. When this method is applicable to conventional 12 pulse converter, the 24 pulse converter, the 24 pulse or 48 pulse converter is controlled by firing angles. The former is performe in 2 tap method when less than 15 degrees, and the letter in 4tap method when more than 15 degrees. Therefore, the proposed method has the advantages of reducing harmonics in full range of control angle and comparison with the conventional 3 tap method. We proved the validity of that theoretically and experimentally.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1540-1547
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• 2000

In this paper, the performance of the MMSE multiuser detector is compared with the conventional detector with respect to the signal-to-noise ratio, the number of users and the Nakagami parameter under AWGN as well as Nakagami fading channel. The results show that the MMSE multiuser detector is superior to the conventional detector with respect to cancelling the multiple access interference. However, its drawback is the hardware's complexity. To solve this drawback, the advanced MMSE multiuser detector is presented, and its performance is analyzed. The number of taps in the advanced MMSE multiuser are independent of the processing gain. Thus, the system engineer can choose the appropriate number of taps in the detector to achieve a optimal trade-off between the hardware complexity and the performance of system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.696-705
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• 1997

This paper presents an efficient adaptive predistortion technique compensating linear and nonlinear distortions caused by high-power amplifier (HPA) with memory in OFDM systems. The efficient adaptive data predistortion techniques proposed for compensation of HPA with memory in single carrier systems cannot be applied to OFDM systems since the possible input levels for HPA is infinite in OFDM systems. Also, previous adaptive predistortion techniques, based on Volterra series modeling, are not suitable for real-time implementation due to high computational burden and slow convergence rate. In the proposed approach, the memoryless HPA preceded by a linear filter in OFDM systems is modeled by the Wiener system which is then precompensated by the proposed adaptive predistorter with a minimum number of filter taps. An adaptive algorithm for adjusting the proposed adaptive predistorter is derived using the stochastic gradient method. It is demonstrated by computer simulation that the performance of OFDM system suffering from nonlinear distortion can be greatly improved by the proposed efficient adaptive predistorter using a small number of filter taps.