• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3215-3226
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• 1996

In this paper a K-band harmonic oscillator competitive to ordinary Push-Push type oscillators is introduced. This oscillator is composed of two-X-band dielectric resonance circuits. To favor its harmonic generation, the load effect and the bias effect are studied to allow the maximum harmonic distortion. As results, the dielectric resonated load and the class A bias are used for the 2nd harmonic generation. analytical study for modelling of voltage controlled dielectric resonator is carried out with theoretical background. The performance of the circuit is evaluated by simulation using harmonic balanced method. The novel structure has ont only a voltage tuning circuit but also an output port at fundamental frequency as the function of prescaler for phase lockede loop application on the just single oscillation structure. In experimentation, the output freqneyc of the 2nd harmonic signal is 20.5GHz and the maximum power level of output is +5.5dBm without additional post amplifiers. the harmonic oscillator exhibits -30dBc of high fundamental frequency rejection without added extra filters. The phase noise of -90dBc/Hz at 100kHz off-carrier has been achieved under free running condition, that satisfies phase noise requirement of IESS 308. The proposed oscillator may be utilized as the clean and stable fixed local oscillator in Transmit Block Upconvertor(TBU) or Low oise Block downconvertor(LNB) for K/Ka-band digital communications and satellite broadcastings.

• Journal of Power Electronics
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• v.15 no.2
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• pp.389-398
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• 2015

This paper presents a 1.92 kW resonant converter for medium voltage applications that uses low voltage stress MOSFETs (500V) to achieve zero voltage switching (ZVS) turn-on. In the proposed converter, four MOSFETs are connected in series to limit the voltage stress of the power switches at half of the input voltage. In addition, three resonant circuits are adopted to share the load current and to reduce the current stress of the passive components. Furthermore, the transformer primary and secondary windings are connected in series to balance the output diode currents for medium power applications. Split capacitors are adopted in each resonant circuit to reduce the current stress of the resonant capacitors. Two balance capacitors are also used to automatically balance the input capacitor voltage in every switching cycle. Based on the circuit characteristics of the resonant converter, the MOSFETs are turned on under ZVS. If the switching frequency is less than the series resonant frequency, the rectifier diodes can be turned off under zero current switching (ZCS). Experimental results from a prototype with a 750-800 V input and a 48V/40A output are provided to verify the theoretical analysis and the effectiveness of the proposed converter.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.2
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• pp.18-26
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• 2005

The balanced scorecard(BSC) overcomes the limit of traditional financial statement that focuses on only financial performance. BSC is widely used in government and industry because of the clear representation of the relationship and logic between the key performance indicators(KPI) of 4 perspectives - financial, customer, internal process, and loaming and growth. However, traditional BSC does not consider evaluating the difference between the results measured by BSC. By using relatively small number of inputs and outputs In comparing decision-making units, data envelopment analysis(DEA) can aggregate multiple performance measures. In this research, we propose a methodology named CDB(Combined DEA and BSC) to evaluate the performance of organization considering financial and non-financial perspectives. CDB uses KPI of cause-and-effect relationship on BSC as inputs and outputs of DEA method. In addition, this research proposes a method of converting the KPI of BSC to the input and output variables of DEA, and enhancing discrimination power using the limit number of variables. We illustrate the methodology by giving an example of evaluating aquisition-unit efficiency in a supply chain.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.5
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• pp.7-14
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• 1977

Conventionally, a TIVT has been used for high power amplification in the microwave frequency range. However, an ultra-high-power amplifier in the 2GHz range has successfully been designed and fabricated employing high power transistors developed recently and available commercially. In the design of the amplifier, a balanced-pair configuration is adopted in order to obtain very high microwave power, and a good impedance matching is achieved by making use of microstripline techniques. For the RF power divider as well as combiner, an approach of stripline directional coupler isadopted because of its easiness in fabrication. The coupler so designed and fabricated indicates a satisfactory performance as a quadrature hybrie coupler. Measurements on the amplifier developed for an immediate commercial application also exhibit excellent overall performance characteristics RF power output, 14 watts, gain 14dB, frequency bandwidth, 160MHz, effciency 40%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.161-166
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• 2005

The synthesis procedure of Marchand balun using planar coupled-line is presented. The design limitations of this type of balun have been described before its synthesis procedure. The balun has equi-ripple passband responses and balanced output without fourth balanced transmission line which is difficult to implement with conventional planar topology. As an example, 2:1 Marchand balun is designed and its momentum simulation result show good verification fur this methodology.

• Communications for Statistical Applications and Methods
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• v.16 no.6
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• pp.903-913
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• 2009

In this paper, we suggested a modified revealed comparative advantage(RRCA) index for identifying regional strategic industries. The index is developed under the assumption that the concentration of industries in Korea is not based entirely on the comparative advantages. The Korean government has set up balanced development strategies since 2003 under the assumption too. The index is the ratio between the comparative advantage index and economic imbalance of the region. By the index, we selected strategic industries for 15 regions under the rule of 1) relative ratio of the index is more than 15%, 2) 1 to 3 regions for a industry according to the industry's output.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.65-70
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• 2004

This paper presents a novel linearization scheme for a nonlinear RF amplifier It is based on the amplitude modulation with envelope signal. The 3rd order distortion generator is composed of two FETs and it adopts a balanced structure for the purpose of main carrier cancellation. The amplitude and phase of the IM3 component can be controlled at RF band. This predistorter is implemented and tested at the KOREA PCS Tx. band (1840∼1870MHz). Experimental results of two-tone test show that the IM3 cancellation is achieved about 30-40 ㏈ for the wide dynamic range. The adjacent channel power ratio is improved by over 10 ㏈ at the broad-band CDMA signal with a peak to average power ratio of l0㏈, and this improvement is maintained through a wide range of output power levels.

• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.299-304
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• 2020

This paper proposes the design of circular sector shaped power divider-combiner with a planar structure. This structure can be constructed in series, and due to the circular sector shape, it is possible to simplify circuit configuration and improve the amplitude and phase balanced characteristics of the output. It has a simple input matching circuit and an RC parallel circuit was inserted between the output ports to improve the reflection coefficient and isolation of the output. Since the designed divider-combiner are structurally designed in a symmetrical shape of a sector, even if the output ports are composed of two or four output ports, they have excellent characteristics with an amplitude balance of ± 0.1 dB and a phase balance of ± 1o between outputs. To prove these characteristics, it was confirmed that the characteristics of the planar power divider-combiner fabricated at an operating frequency of 2 GHz are in good agreement with the simulation.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.57-67
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• 2009

Packet forwarding in the Internet routers is to find out the longest prefix that matches the destination address of an input packet and to forward the input packet to the output port designated by the longest matched prefix. The IP address lookup is the key of the packet forwarding, and it is required to have efficient data structures and search algorithms to provide the high-speed lookup performance. In this paper, an efficient IP address lookup algorithm using binary search is investigated. Most of the existing binary search algorithms are not efficient in search performance since they do not provide a balanced search. The proposed binary search algorithm performs perfectly balanced binary search using switch pointers. The performance of the proposed algorithm is evaluated using actual backbone routing data and it is shown that the proposed algorithm provides very good search performance without increasing the memory amount storing the forwarding table. The proposed algorithm also provides very good scalability since it can be easily extended for multi-way search and for large forwarding tables

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.25-28
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• 2010

The need for multiband RF front-end in modern communication system is growing rapidly. For example, satellite system always uses a complex arrangement of frequency plans and consequently needs filters for each communication channel and it will be ideal to have a single filter module that does jobs of all those channel filters to reduce the size and payload of the system. In this paper, a new method to transform four-port self-feedback balanced dual-band bandpass filter into two-port is proposed. The two-port balanced dual-band bandpass filter which has baluns at the input and output ports and the fundamental frequency at 2.5 GHz and the first harmonic frequency at 5.7 GHz is fabricated and measured. Good agreement between measured and simulated results was achieved.