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ChangChun Chen,BenHai Yu,JiangFeng Liu 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5
Structural and optical properties have been investigated for Ru2Si3 layers on Si (100) formed by two-step channeled ion implantations (70 keV, 6.92 × 1016/㎠ and 40 keV, 4.31 × 1016/㎠) and subsequent annealing at 1150℃ for 120 second. Rutherford backscattering/ ion channeling (RBS/C) analyses have revealed that the Ru2Si3 layers were grown on the Si substrate but with a rather poor crystalline quality. The optical spectra have been obtained by spectroscopic ellipsometry (SE) and optical absorption measurements. From the optical investigations, the real and imaginary parts of the dielectric function as well as the absorption coefficient have been derived. The spectra of Ru2Si3 layers exhibit a semi-conducting character with an allowed direct band gap of 0.843 eV. Structural and optical properties have been investigated for Ru2Si3 layers on Si (100) formed by two-step channeled ion implantations (70 keV, 6.92 × 1016/㎠ and 40 keV, 4.31 × 1016/㎠) and subsequent annealing at 1150℃ for 120 second. Rutherford backscattering/ ion channeling (RBS/C) analyses have revealed that the Ru2Si3 layers were grown on the Si substrate but with a rather poor crystalline quality. The optical spectra have been obtained by spectroscopic ellipsometry (SE) and optical absorption measurements. From the optical investigations, the real and imaginary parts of the dielectric function as well as the absorption coefficient have been derived. The spectra of Ru2Si3 layers exhibit a semi-conducting character with an allowed direct band gap of 0.843 eV.
Investigation of nano-sized ZnO particles fabricated by various synthesis routes
Changchun Chen,Benhai Yu,Ping Liu,JiangFeng Liu,Lin Wang 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.4
Nano-sized ZnO particles were synthesized by a direct precipitation, a sol-gel, and a hydrothermal method. The structures,morphology, and optical properties of these ZnO nanoparticles fabricated by the above-mentioned methods were also characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Ultraviolet-visible spectroscopy (UV-vis). In addition, the photocatalytic activities of the synthesized ZnO nanoparticles were evaluated via the degradation of methyl orange (MO) in an aqueous solution. These experimental results demonstrated that the photodegradation efficiency of MO solutions irradiated by UV for 120 minutes with ZnO nano-particles used as catalysts, which were fabricated by a direct precipitation method could reach 94.59% or so. The higher photocatalytic activity of methyl orange solutions by the ZnO nanoparticles synthesized by the direct precipitation method is probably ascribed to the spherical ZnO nanoparticles with a smaller crystalline size.
Robust semi-autonomous vehicle control for roadway departure and obstacle avoidance
Changchun Liu,Jun Zheng,Jiluan Pan 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
This paper presents the design of a robust active safety system for prevention of unintended collisions and roadway departures. The safety system shares control with the driver and corrects the driver’s steering and braking action only if there is a potential risk. We formulate the safety problem as constrained optimization problem using uncertain evolution set based MPC. In the scheme, we compute the set of possible trajectories with uncertain driver model and issue minimal steering and(or) braking action, only if necessary, to keep the set in safety constraints. Human in loop simulation experiments were conducted, the results demonstrate the robustness of proposed controller to uncertain input from drivers.
Re-tested Parametric Multiple Testing Methods for Correlated Tests
Changchun Xie 계명대학교 자연과학연구소 2013 Quantitative Bio-Science Vol.32 No.1
In clinical trials, multiple endpoints are often correlated. To control the family-wise type I error rate, Huque and Alosh’s flexible fixed-sequence (FFS) testing method and Li and Mehrotra’s adaptive alpha allocation approach (4A) have taken into account correlations among endpoints. I suggested a weighted multiple testing correction (WMTC) for correlated tests and compared it with FFS and 4A. The WMTC method is a re-tested method while the FFS and 4A methods are not. In this paper, we propose a re-tested FFS method and a re-tested 4A method. Simulations are conducted to compare them with the WMTC and the original FFS and 4A methods.
A 15 GHz, <tex> $-$</tex>182 dBc/Hz/mW FOM, Rotary Traveling Wave VCO in 90 nm CMOS
Changchun Zhang,Zhigong Wang,Yan Zhao,Sung Min Park THE INSTITUTE OF ELECTRICAL ENGINEERS 2012 IEEE Microwave and Wireless Components Letters Vol. No.
<P>This letter presents a phase-noise-centric design methodology of a rotary traveling wave voltage controlled oscillator (RTW VCO). Based upon this methodology, a 15 GHz multiphase RTW VCO is realized in a standard 90 nm CMOS process. Particularly, shielded coplanar striplines are exploited to provide better shielding protection and higher characteristic impedance with comparable Q-factor than conventional coupled transmission lines. Measured results of the proposed RTW VCO demonstrates the frequency tuning range of 2 GHz, the output power level of 11.3 dBm, the phase noise of 109.6 dBc/Hz at 1 MHz offset, the clock RMS jitter of 2 , and the power dissipation of 12 mW from a single 1.2-V supply. The chip core occupies the area of 0.2 .</P>
A 15-㎓ CMOS Multiphase Rotary Traveling-Wave Voltage-Controlled Oscillator
Changchun Zhang,Zhigong Wang,Yan Zhao,Sung Min Park 대한전자공학회 2012 Journal of semiconductor technology and science Vol.12 No.3
This paper presents a 15-㎓ multiphase rotary traveling-wave voltage-controlled oscillator (RTW VCO) where a shielded coplanar stripline (CPS) is exploited to provide better shielding protection and lower phase noise at a moderate cost of characteristic impedance and power consumption. Test chips were implemented in a standard 90-㎚ CMOS process, demonstrating the measured results of 2-㎓ frequency tuning range, -11.3-㏈m output power, -109.6-㏈c/㎐ phase noise at 1-㎒ offset, and 2-ps RMS clock jitter at 15 ㎓. The chip core occupies the area of 0.2 ㎟ and dissipates 12 ㎽ from a single 1.2-V supply.
A self-normalization test for a change-point in the shape parameter of a gamma distributed sequence
Changchun Tan,Yuehua Wu,Cuiling Dong,Baiqi Miao 한국통계학회 2013 Journal of the Korean Statistical Society Vol.42 No.3
In this paper, a parametric change-point problem encountered in analyzing a gamma distributed sequence is considered. We propose a self-normalization based CUSUM type test statistic to detect the presence of a change-point, and obtain its limiting null distribution. The CUSUM-based procedure for detecting the location of this change-point is also given. At the same time, simulation results are provided, which show that our procedures are effective.
Multi-channel 5Gb/s/ch SERDES with Emphasis on Integrated Novel Clocking Strategies
Changchun Zhang,Ming Li,Zhigong Wang,Kuiying Yin,Qing Deng,Yufeng Guo,Zhengjun Cao,Leilei Liu 대한전자공학회 2013 Journal of semiconductor technology and science Vol.13 No.4
Two novel clocking strategies for a high-speed multi-channel serializer-deserializer (SERDES) are proposed in this paper. Both of the clocking strategies are based on groups, which facilitate flexibility and expansibility of the SERDES. One clocking strategy is applicable to moderate parallel I/O cases, such as high density, short distance, consistent media, high temperature variation, which is used for the serializer array. Each group within the strategy consists of full-rate phase-locked loop (PLL), a full-rate delay-locked loop (DLL), and t재 fixed phase alignment (FPA) techniques. The other is applicable to more awful I/O cases such as higher speed, longer distance, inconsistent media, serious crosstalk, which is used for the deserializer array. Each group within the strategy is composed of a PLL and two DLLs. Moreover, a half-rate version is chosen to realize the desired function of 1:2 deserializer. Based on the proposed clocking strategies, two representative ICs for each group of SERDES are designed and fabricated in a standard 0.18㎛ CMOS technology. Measurement results indicate that the two SERDES ICs can work properly accompanied with their corresponding clocking strategies.