• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.65-65
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• 1991

레이저 분광학의 연구에 있어서 고출력이며 좁은 선폭인 레이저광이 요구된다. 특히 고리형 공진기 레이저는 이득물질에서 공간 홀 버닝 효과 (Spatial Hole Burning effect)를 줄이거나 없앨수 있으므로 정상파로 발진하는 레이저에 비하여 높은 출력의 단일모드 발진을 얻을 수 있다. 8자형 고리 공진기 레이저에서 외부 되반사경과 코팅되지않은 에탈론의 조합을 사용하여 높은 출력의 단일모드를 얻었다. 색소분자의 에너지 준위를 2준위 구조로 가정하여 고리형 색소레이저에 있어서의 단일모드 발진의 안정성(Stability)을 살펴보았으며 양방향으로 단일모드 발진을 하는 경우에 있어서의 쌍안정(Bistability) 상태를 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.4 s.346
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• pp.75-80
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• 2006

This paper has proposed a novel dual band transmitter module which can be operating either as an amplifier or as a frequency multiplier according to the input frequency. A conventional dual band transmitter consists of separate amplifiers operating at each frequency band, but the proposed dual band module operates as an amplifier for the IEEE 802.11b/g signal, and as a frequency doubler for the IEEE 802.11a signal according to input frequency and bias voltage. In this paper, we have obtained sharp stop band characteristics by using microstrip DGS(Defected Ground Structure) to suppress the fundamental frequency of the frequency doubler as well as the second harmonic of the amplifier. From measurement result, second harmonic suppression is below -59dBc in the amplifier mode, and fundamental suppression is below -35dBc in the frequency doubler mode. And the designed module has 17.8dBm output P1dB at 2.4GHz and 10.1dBm power for 5.8GHz output, and the output power in the two modes are 0.8dB and 2.8dB larger than the module with ${\lambda}g/4$ reflector, respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.162-168
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• 2005

In this paper, a digital current mode control is designed for the power converter applications. The designed digital current mode controller is derived analytically from the continuous time small signal model of the power converters. Due to the small signal model based derivations of the control law, the designed control method can be applicable to boost, buck, and buck-boost converters. It is also proven that the controlled power converter employing the designed digital current mode controller is always stable regardless of an operating conditions. In order to show the usefulness of a designed controller, experiments are carried out using a 16bit DSP micro-processor, TMS320LF2406A.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.288-290
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• 2014

In this paper, Escape and BTA(Bus Turn Around) modes of master bridge IC are implemented, which supports MIPI(Mobile Industry Processor Interface) DSI(Display Serial Interface) standard. MIPI DSI master bridge IC sends RGB data and various commands to display module(slave) in order to test it. The Escape mode is designed to implement LPDT, ULPS and trigger message transmissions. The BTA mode is designed to obtain various status information from slave in reverse direction. Functional simulation results show that the designed Escape and BTA modes work correctly for various conditions defined in MIPI DSI standard.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.12
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• pp.19-26
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• 2005

We have studied the relationship between static mode behavior and dynamic characteristics of multiple transverse-mode VCSELs by measuring the modal L-I and I-V characteristics. Dependence of the resonance frequencies of RIN (relative intensity noise) spectra on the injection current can be understood by modal L-I characteristics and mode-coupling effects. Each transverse mode behaves as an independent diode laser with the different threshold current in large active-area VCSELs, and the multiple-step turn-on is observed when step-current input is applied. This multiple-step turn-on is a result of different turn-on delay times of the transverse modes. Since the multiple-step turn-on increases the rise-time significantly, the wide active-area VCSELs are not suitable for high-speed optical transmitters unless the input current is adjusted for single transverse-mode operation.

• ICROS
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• v.22 no.2
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• pp.34-41
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• 2016

슬라이딩 모드 기법을 실제 적용하는데 있어서 고려해야 할 중요한 문제 중 하나는 스위칭 동작에 의한 채터링 현상이다. 본 논문은 슬라이딩 모드 제어기 및 관측기의 게인을 줄임으로써 채터링을 완화하기 위한 방법으로 슬라이딩 모드 외란 관측기와 적분 제어를 포함하는 슬라이딩 모드 제어 기법에 대해 소개한다. 슬라이딩 모드 외란 관측기는 시스템 불확실성에 의해 발생하는 등가 외란의 상대적으로 느리게 변하는 부분을 추정하도록 설계한다. 슬라이딩 모드 관측기로 추정된 불확실성을 슬라이딩 모드 제어 입력에 결합함으로써 제안하는 관측기 기반 제어기는 상대적으로 낮은 게인을 사용하여 제어 목표를 달성할 수 있다. 본 논문에서 제안하는 제어기의 성능을 기존 방법과 비교하기 위해 DC 모터 전류 제어 모의실험을 수행한다. 모의실험 결과를 통해 제안하는 슬라이딩 모드 외란 관측기 기반 제어기는 낮은 게인으로 강인한 성능을 달성하고 전류 맥동을 줄일 수 있음을 확인할 수 있다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.8
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• pp.96-101
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• 2007

Gas Discharge Tubes (GDTs) are widely used as surge protectors for communication applications due to their small internal capacitance. In these days, however, they are mostly used in combined configurations, because the sparkover voltage required to initiate the discharge process in the GDTs and the time taken for arc formation process can be large enough to damage to sensitive circuits. For GDTs with a considerably high initial residual voltage, we should limit the peak voltage using a TVS or filter. We made a hybrid SPD circuits of common-mode type and differential-mode type with the filter using common-mode choke. Also, we applied lightning impulse voltage and ring wave voltage which frequency bandwidth are different each other and verified the characteristics of hybrid SPD circuits according to waveshapes. We describe how the applied SPDs operate in protection process steps with the actual data obtained from the residual voltage measurement at each step. The experiment results show that the surge voltage reduction with the choke coil is more effective in differential-mode circuit than in common-mode circuit.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.77-86
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• 2016

This paper describes a dual-mode reference-less CDR(Clock Data Recovery) operating at full / half-rate and its operation algorithm. Proposed reference-less CDR consists of a frequency detector, a phase detector, a charge pump, a loop filter, a voltage controlled oscillator, and a digital block. The frequency and phase detectors operate at both full / half-rate for dual-mode operation and especially the frequency detector is capable of detecting the difference between data rate and clock frequency in the dead zone of general frequency detectors. Dual-mode reference-less CDR with the proposed algorithm can recover the data and clock within 1.2-1.3 us and operates reliably at both full-rate (2.7 Gb/s) and half-rate (5.4 Gb/s) with 0.5-UI input jitter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.872-875
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• 2016

In this paper, the turnstile junction-based Ortho-Mode Transducer(OMT) is designed and manufactured. It is usually well-known that turnstile junctions have symmetry structure of waveguide so the higher order modes, which occurs inside the waveguide, can be cancelled. Because of these symmetrical properties, the turnstile junction-based OMTs have merits like high transmission and low return loss characteristic in broadband and two different modes propagate orthogonally in common port resulting in the fully realization of double polarization. The designed OMT has the application of Radar Seeker and operates in W-band(94 GHz), the millimeter wave frequency. The average of return loss value of manufactured OMT is lower than -20 dB and it has bandwidth characteristic of over 500 MHz.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.869-872
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• 2005

This paper presents a new switchable dual mode VCO(Voltage-Controlled Oscillator). The VCO is efficient in dual mode operation and has self-bias adjustment based on the operation frequencies of 2.4 GHz and 5 GHz. The switching is done using MOS transistors and tuning is done using MOS varactors. It is implemented using TSMC 0.18${\mu}$m CMOS technology. It is powered by 1.8V supply. The measured results showed that the overall tuning range is approximately 13% at 5 GHz and 8% at 2.4 GHz. The measured phase noise is approximately -102 dBc/Hz at 1 MHz offset for 5 GHz and -89 dBc/Hz at 600kHz offset for 2.4 GHz. The VCO showed tail currents of 2mA in 5GHz mode and 2.5mA in 2.4GHz mode from a 1.8 V supply, respectively.