• Bulletin of the Korean Chemical Society
• /
• 제30권11호
• /
• pp.2754-2758
• /
• 2009

Three novel phosphorescent 2-phenylpyridine-based iridium(III) complexes, $[(ppy)_2Ir(P\^{}N)]PF6\;(1),\;[(dfppy)_2Ir(P\^{}N)]PF_6$ (2), and $[(dfmppy)_2 Ir(P\^{}N)]PF6$ (3), where $P\^{}N$ = 2-[(diphenylphosphino)methyl]pyridine (dppmp), were synthesized and characterized. The absorption, photoluminescence, cyclic voltammetry and thermal stability of the complexes were investigated. The complexes showed bright blue luminescences at wavelengths of 448 $\sim$ 500 nm at room temperature in $CHCl_3$ and revealed that the $\pi$-acceptor ability of the phosphorous atom in the ancillary dppmp ligand plays an important role in tuning emission color resulting in a blue-shift emission. The single crystal structure of $[(dfmppy))_2Ir(P\^N)]PF_6$ was determined using X-ray crystallography. The iridium metal center adopts a distorted octahedral structure coordinated to two dfmppy and one dppmp ligand, showing cis C-C and trans N-N chelate dispositions. There is a $\pi-\pi$ overlap between π electrons delocalized in the difluorophenyl rings.

• 한국정보통신학회논문지
• /
• 제9권2호
• /
• pp.262-267
• /
• 2005

본 논문에서는 여러 가지 효율 개선 방법 중에서 Doherty Amplifier에 관해 논하였다. 간단한 회로를 이용하여 하나의 PEP 180w급 LDMOS를 사용하여 효율성과 선형성 개선에 관한 성능분석을 하였다 제작된 Doherty Amp의 성능을 검증하기 위해 Balanced Class AB Amplifier와 성능을 비교하였다. 실험결과 peaking Amp의 $V_gs.P$가 1.53V일 때 효율이 최대 11.6$\%$ 이상 증가되었으며 매뉴얼로 gate bias 조절을 통하여 선형성 개선의 최적 bias point를 찾은 후 WCDMA 4fA에서는 $V_gs.P$가 3.68V일 때 IMSR (InterModulation to Signal Ratio)이 최대 3.34dB가 증가됨을 보였다. 특히 1.53V로 peaking amp의 bias point를 맞추게 되면 출력 전력 434Bm에서 -324Bc 이하의 IMSR과 탁월한 효율 증가를 얻을 수 있었다.

• 한국세라믹학회지
• /
• 제41권5호
• /
• pp.381-387
• /
• 2004

현재 상용화되어 있는 PDP용 형광체의 물성에 있어서 청색 형광체는 열화, 색도변화, 휘도, 그리고 녹색 형광체는 잔광시간과 색순도, 적색 형광체의 경우에는 색순도에 대한 개선이 필요한 것으로 알려져 있다. 그 중 녹색 형광체로 Willemite 구조의 ZnSiO:Mn 형광체의 경우 발광효율은 우수하나 반면에 잔광시간이 길고 색순도(color purity)가 좋지 않다는 단점을 가지고 있다. 따라서 본 연구에서는 미세조정 조합화학기법을 이용하여 PDP에 적합한 새로운 고효율 형광체를 개발하였다. 화학적으로 정량인 가돌리늄 인산염(gadolinium phosphorous) 대신 인산을 과잉으로 첨가하여 탐색한 다음 과잉인산(excess phosphorous) 첨가 조성을 유지한 채로 가돌리늄(gadolinium)의 일정분율을 이트륨(yttrium)으로 치환하였다. 그 결과 최적 형광체 조성은 (G $d_{0.74}$ $Y_{0.11}$T $b_{0.15}$) $P_{1.15}$ $O_{{\delta}}$이였으며, 현재 상용화된 Z $n_2$ $SiO_4$:Mn 형광체에 비해 상대적으로 높은 발광효율을 나타내었으며, 잔광시간도 줄일 수 있게 되었다.

• 한국전자파학회논문지
• /
• 제18권2호
• /
• pp.177-182
• /
• 2007

본 논문은 InGaP/GaAs HBT 공정을 통해 제작한 적응성궤환 잡음제거시스템용 낮은 위상잡음을 갖는 LC 차동 전압제어 발진기를 제안합니다. 전압제어 발진기는 필터링 기술을 포함한 향상된 공진 탱크 구조를 갖습니다. 비대칭 인덕터 대칭 캐패시터 구조로 제안된 전압제어 발진기의 출력 가변 범위는 207 MHz입니다. 출력 전력은 balun과 케이블 손실을 포함하여 -6.68 dBm입니다. 10 kHz, 100 kHz, 1 MHz에서의 위상잡음은 각각 -102.02, -112.04 그리고 -130.4 dBc/Hz입니다. 이 전압제어 발진기는 총 $0.9{\times}0.9mm^2$ 면적 내에 집적화되었습니다.

• 전자공학회논문지SC
• /
• 제46권2호
• /
• pp.72-77
• /
• 2009

본 논문은 별도 기준 클록 없이 고속 시리얼 데이터 통신을 위한 3.2Gb/s 클록 데이터 복원(CDR) 회로를 설명한다. CDR회로는 전체적으로 5부분으로 구성되며, 위상검출기(PD)와 주파수 검출기(FD), 다중 위상 전압 제어 발진기(VCO), 전하펌프(CP), 외부 루프필터(LF)로 구성되어 있다. CDR회로는 half-rate bang-bang 타입의 위상 검출기와 입력 pull-in 범위를 늘릴 수 있도록 half-rate 주파수 검출기를 적용하였다. VCO는 4단의 차동 지연단(delay cell)으로 구성되어 있으며 튜닝 범위와 선형성 향상을 위해 rail-to-rail 전류 바이어스단을 적용하였다 각 지연단은 풀 스윙과 듀티의 부정합을 보상할 수 있는 출력 버퍼를 갖고 있다. 구현한 CDR회로는 별도의 기준 클록 없이 넓은 pull-in 범위를 확보할 수 있으며 기준 클록 생성을 위한 부가적인 Phase-Locked Loop를 필요치 않기 때문에 칩의 면적과 전력소비를 효과적으로 줄일 수 있다. 본 CDR 회로는 0.18um 1P6M CMOS 공정을 이용하여 제작하였고 루프 필터를 제외한 전체 칩 면적은 $1{\times}1mm^2$이다. 3.2Gb/s 입력 데이터 율에서 모의실험을 통한 복원된 클록의 pk-pk 지터는 26ps이며 1.8V 전원전압에서 전체 전력소모는 63mW로 나타났다. 동일한 입력 데이터 율에서 테스트를 통한 pk-pk 지터 결과는 55ps였으며 신뢰할 수 있는 입력 데이터율 범위는 약 2.4Gb/s에서 3.4Gb/s로 나타났다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.157-157
• /
• 2008

As the minimum feature size of semiconductor devices scales down to nano-scale regime, ultra shallow junction is highly necessary to suppress short channel effect. At the same time, Ni-silicide has attracted a lot of attention because silicide can improve device performance by reducing the parasitic resistance of source/drain region. Recently, further improvement of device performance by reducing silicide to source/drain region or tuning the work function of silicide closer to the band edge has been studied extensively. Rare earth elements, such as Er and Yb, and Pd or Pt elements are interesting for n-type and p-type devices, respectively, because work function of those materials is closer to the conduction and valance band, respectively. In this paper, we increased the work function between Ni-silicide and source/drain by using Pd stacked structure (Pd/Ni/TiN) for high performance PMOSFET. We demonstrated that it is possible to control the barrier height of Ni-silicide by adjusting the thickness of Pd layer. Therefore, the Ni-silicide using the Pd stacked structure could be applied for high performance PMOSFET.

• Steel and Composite Structures
• /
• 제51권5호
• /
• pp.509-527
• /
• 2024

Bonding carbon fiber-reinforced polymer (CFRP) laminates have been extensively employed in the restoration of steel constructions. In addition to the mechanical properties of the CFRP, the bond strength (P_U) between the CFRP and steel is often important in the eventual strengthened performance. Nonetheless, the bond behavior of the CFRP-steel (CS) interface is exceedingly complicated, with multiple failure causes, giving the P_U challenging to forecast, and the CFRP-enhanced steel structure is unsteady. In just this case, appropriate methods were established by hybridized Random Forests (RF) and support vector regression (SVR) approaches on assembled CS single-shear experiment data to foresee the P_U of CS, in which a recently established optimization algorithm named Aquila optimizer (AO) was used to tune the RF and SVR hyperparameters. In summary, the practical novelty of the article lies in its development of a reliable and efficient method for predicting bond strength at the CS interface, which has significant implications for structural rehabilitation, design optimization, risk mitigation, cost savings, and decision support in engineering practice. Moreover, the Fourier Amplitude Sensitivity Test was performed to depict each parameter's impact on the target. The order of parameter importance was t_c> L_c > E_A > t_A > E_c > b_c > f_c > f_A from largest to smallest by 0.9345 > 0.8562 > 0.79354 > 0.7289 > 0.6531 > 0.5718 > 0.4307 > 0.3657. In three training, testing, and all data phases, the superiority of AO - RF with respect to AO - SVR and MARS was obvious. In the training stage, the values of R² and VAF were slightly similar with a tiny superiority of AO - RF compared to AO - SVR with R² equal to 0.9977 and VAF equal to 99.772, but large differences with results of MARS.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1012-1015
• /
• 2003

Recently technologies have created new principle and theory but the PID control system remains its popularity as the PID controller contains simple structure, including maintenance and parameter adjustment being so simple. The adjust parameter of PID to achieve best response of process which be using time and may be error if user are not expert. Nowadays this problem was solved by develop PID controller which can analysis and auto tune parameter are appropriate with process which used principle of Ziegler ? Nichols but it are expensive and designed for each task. Thus, this paper proposes auto tune PID based on FPGA by use principle of Dahlin which maximum overshoot not over 5 percentages and do not fine tuning again. It have performance in control process are neighboring controller in industrial and simple to use. Especially, It can use various process and low price. The auto tune digital PID processor embedded on chip FPGA XC2S50-5tq-144. The digital PID processor was designed by fundamental PID equation which architectures including multiplier, adder, subtracter and some other logic gate. It was verified by control model of temperature control system.

• Journal of Electrical Engineering and Technology
• /
• 제10권4호
• /
• pp.1508-1517
• /
• 2015

Optimal Power dispatch is the short-term decision of the optimal output of a number of power generation facilities, to meet the system demand, with the objective of Power dispatching at the lowest possible cost, subject to transmission lines power loss and operational constraints. The operational constraint includes power balance constraint, generator limit constraint, and emission dispatch constraint and valve point effects. In this paper, Opposition based Differential Evolution Algorithm (ODEA) has been proposed to handle the objective function and the operational constraints simultaneously. Furthermore, the valve point loading effects and transmission lines power loss are also considered for the efficient and effective Power dispatch. The ODEA has unique features such as self tuning of its control parameters, self acceleration and migration for searching. As a result, it requires very minimum executions compared with other searching strategies. The effectiveness of the algorithm has been validated through four standard test cases and compared with previous studies. The proposed method out performs the previous methods.

• Bulletin of the Korean Chemical Society
• /
• 제28권12호
• /
• pp.2333-2337
• /
• 2007

Nanoporous TiO2 and ZrO2 thin films were spin-coated using a surfactant-templated approach from Pluronic P123 (EO20PO70EO20) as the templating agent, titanium alkoxide (Ti(OC4H9)4) as the inorganic precursor, and butanol as a the solvent. The control of the electronic structure of TiO2 is crucial for its various applications. We found that the band gap of the hybrid nanoporous thin films can be easily tuned by adding an acetylacetonestabilized Zr(OC4H9)4 precursor to the precursor solution of Ti(OC4H9)4. Pores with a diameter of 5 nm-10 nm were randomly dispersed and partially connected to each other inside the films. TiO2 and ZrO2 thin films have an anatase structure and tetragonal structure, respectively, while the TiO2-ZrO2 hybrid film exhibited no crystallinity. The refractive index was significantly changed by varying the atomic ratio of titanium to zirconium. The band gap for the nanoporous TiO2 was estimated to 3.43 eV and that for the TiO2-ZrO2 hybrid film was 3.61 eV.