• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.73-76
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• 1997

A low loss x-cut LiNbO$_3$ optical waveguide was fabricated by Ti in-diffusion and the guided-mode properties and total insertion loss of pigtailing with polarization maintaining fiber(PMF) were investigated and measured at optical wavelength 15507. For formaing the waveguide, the parameters of diffusion Ti thickness, waveguide line-width, length, diffusion temperature, time and atmosphere were set 1400$\AA$, 8${\mu}{\textrm}{m}$, 3.3cm, 105$0^{\circ}C$, 8 hours and wet bubbled oxygen, respectively. and then After the polishing and pigtailing, it showed that total insertion loss was -4.1dB for TM mode, -5.5dB for TE mode, and mode size, that is, horizontal/vertical sizes were 13.87/18${\mu}{\textrm}{m}$ for TM mode, 9.61${\mu}{\textrm}{m}$/6.5${\mu}{\textrm}{m}$ for TE mode.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.7
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• pp.42-48
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• 1994

In this paper, a low power and high speed flash Analog-to-Digital Converter using current-mode concept is proposed. Current-mode approach offers a number of advantages over conventional voltage-mode approach, such as lower power consumption small chip area improved accuracy etc. Rescently this concept was applied to algorithmic A/D Converter. But, its conversion speed is limited to medium speed. Consequently this converter is not applicable to the high speed signal processing system. This ADC is fabricated in 1.2um double metal CMOS standard process. This ADC's conversion time is measured to be 7MHz, and power consumption is 2.0mW, and differential nonlinearity is less than 1.14LSB and total harmonic distortion is -50dB. The active area of analog chip is about 350 x 550u$m^2$. The proposed ADC seems suitable for a single chip design of digital signal processing system required high conversion speed, high resolution small chip area and low power consumption.

• Journal of the military operations research society of Korea
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• v.10 no.2
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• pp.61-73
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• 1984

A block replacement policy using items with different reliability is discussed. We divide system unit failure modes into two modes and use less reliable unit when operating unit fails near the planned preventive replacement time. In this policy, item A has two failure modes. Mode-1 failure is removed by minimal repair, mode-2 failure by replacement. If mode-2 failure of item A happens in (0, $T-{\delta}$), failure item A is replaced by new item A. If mode-2 failure of item A happens in ($T-{\delta}$, T), failure item A is replaced by new item B. Item B should be cheaper and less durable than item A. Under this policy, we determine the preventive replacement interval $T^{*}$ and the interval ${\delta}^{*}$ of item B replacement which minimize the cost rate per unit time.

• ETRI Journal
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• v.6 no.3
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• pp.17-20
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• 1984

A block replacement policy using items with different reliability is discussed. We devide system unit failure modes into two modes and use less reliable unit when operating unit fails near the planned preventive replacement time. In this policy, item A has two failure modes. Mode-1 failure is removed by minimal repair, mode-2 failure by replacement. If mode-2 failure of item A happens in (0,T- $\delta$). failure item A is replaced by new item A. If mode-2 failure of item A happens in(T-$\delta$,T), failure item A is replaced by new item B. Item B should be cheaper and less durable than item A. Under this policy, we determine the preventive replacement interval T and the interval $\delta$ of item B replacement which minimize the cost rate per unit time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.5
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• pp.502-507
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• 2013

In this paper, a circular dual mode horn with modified aperture is proposed to improve a E/H-plane radiation pattern symmetry of a conventional oversized circular dual mode horn. The proposed antenna consists of a feeding section, a mode generation section and a phase matching section which has aperture shape transition from circle to ellipse or rectangle to improve a E/H-plane radiation pattern symmetry. To compare the performances between the proposed antenna and the convenional circular dual mode horn, the conventional circular dual mode horn and the proposed circular dual mode horn with rectangular aperture are fabricated and researched at 15 GHz. The measured results show that the conventional circular dual mode horn has 3.394 dB difference while the proposed antenna has only 0.539 dB difference between E and H-plane radiation patterns within the -11 dB beamwidth($53^{\circ}$) which is required beamwidth of the feed horn for the maximum aperture efficiency where f/d ratio of reflector antenna is 1.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.17-23
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• 2007

This paper, describes the VDR physical layer design in VDL Mode-2 in order to meet the requirements of International standards. VDR's frequency band is 117.975~137MHz, and CSMA(Carrier Sense Multiple Access), D8PSK(Differential Eight Phase Shift Keyed), 25KHz's channel bandwidth use. The analysis of the isolated channel from near channels, sensitivity of the receiver, dynamic range of the receiver, linear of the transmitter and energy of spurious for linear and non-linear simulation as a requirement condition of performance of VDR and teaches the course of design. The transmitting power level should be lower than 5dB from Po1dB point and the selected IF frequency is 45MHz to suppress the spurious signals. The receiver designed has 4.5dB of Noise figure, 27.52dB of Es/No, Mixer isolation up to 30dB, IIP3 power of LNA up to +10dBm to minimize the intermodulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.1-7
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• 2016

In this paper, the tunable filter based on high power cavity using mechanical switch for 1.5 GHz band is presented. The LPF is inserted to eliminate the spurious wave, coupler is embeded to extract the output power, and then the tunable filter system is configured using mechanical switch. The LPF obtains attenuation over 40 dB between 4 GHz and 12.75 GHz, Coupler is satisfied with coupling value 40 dB and coupling isolation over 55 dB. The tunable filter system using mechanical switch obtains insertion loss 0.88 dB at bypass mode between 1,495.9 MHz and 1,510. 9 MHz, 3.29 dB at fil mode between 1,495.9 MHz and 1,500.9 MHz. It is also satisfied with output power of 132 W at the center frequency 1,498.4 MHz, and switching time below 10 ms.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.41-46
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• 2023

Design of W-band TE10 to TEM mode converter for radial power combiner is proposed in this paper. The proposed structure is used with generally available pin to realize TEM mode and is designed to convert TE10 to TEM mode gradually using 2-step impedance transformer and back short. The pin of proposed mode converter is well bonded to the housing so that environment conditions such as vibration or shock are not affected. The proposed mode converter, in a back-to-back configuration, has less than 1.55 dB insertion loss and more than 10 dB return loss from 92.5 GHz to 97.7 GHz. Proposed converter is expected compact radar and various applications requiring for high power and stable environment conditions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1047-1054
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• 2013

In this paper, we propose a dual-mode mixer to have multi-band radar signal receiver to be compact. The proposed mixer using a anti-parallel diode is operated as a fundamental mixer or sub-harmonic mixer with respect to a control voltage. A fundamental mixer with a control voltage show a conversion loss of -10 dB, 1dB compression point of 2 dBm at X-band. On the other hand, it is performed as a sub-harmonic mixer with a conversion loss of -10 dB, 1 dB compression point of 2 dBm at K-band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.2
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• pp.505-513
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• 1996

In this paper the dual-mode bandpass filters with a Chebyshev response are designed and manufactured at Ku-band as well as K-band. Manufactured filters are resonated by two independent orthogonal $TE_{113}$ circular-cavity modes and characterized by 4-pole Chebyshev function. One is operating at a center frequency of 12.5GHz with a bandwidth of 100MHz and the other, a center frequency of 19.25GHz with 120MHz, respectively. The measureed experimental results of a 12.5GHZ dual-mode filter ahve a 1.2dB intertion loss in the passband and 65dB out-of-rejection, and a 19.25GHz filter has a 1.55dB insertion loss and 70dB out-of-rejection. These experimantal results shoults show good agreements with the design specifications.