• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.989-993
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• 2001

The carbonyl stretching vibration, νC=O of 2-cyclohexene-1-one, is in Fermi resonance with a combination tone. The amount of Fermi resonance interaction between these two modes is dependent upon the amount of solute/solvent interaction due to hyd rogen bonding between the carbonyl oxygen and the solvent proton. The corrected νC=O frequency of 2-cyclohexene-1-one occurs at a lower frequency than the observed νC=O mode of cyclohexanone, possibly caused by expanded conjugation effects. The carbonyl stretching modes of cyclic ketones were also affected by interaction with the ROH/CCl4 mixed solvent system.

• Journal of Surface Science and Engineering
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• v.57 no.5
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• pp.379-385
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• 2024

Al-Ag thin films with varying compositions were fabricated using a combinatorial sputtering system to develop highly sensitive SAW devices. The Al-Ag sample library exhibited a wide range of electrical resistivity and chemical compositions, providing valuable data for selecting optimal materials. Recognizing the significant influence of both resistivity and density of IDT electrodes on the generation of acoustic waves from piezoelectric materials, three types of Al-Ag thin films with different Al contents were fabricated, maintaining a consistent thickness of 150 nm. As the Al content decreased from 84.6 at% to 21.7 at%, the resistivity increased from 5.1 to 0.8 × 10^-5 Ω-cm, while the calculated density increased from 3.9 to 8.8 g/cm³. The SAW devices fabricated with these Al-Ag IDT electrodes resonated at 71 MHz without frequency shifts, but the resonant frequency selectivity and insertion loss deteriorated with decreasing Al content, highlighting the predominant influence of electrode density over electrical conductivity on SAW device performance.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.217-220
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• 2004

This paper presents design simulation, implementation, and measurement of a miniaturized GPS/K-PCS dual-band LTCC chip antenna for mobile communication handsets. The dimension of LTCC chip antenna is $9mm{\times}15mm{\times}1.2mm$. The lower meander type antenna is to be tuned to the lower frequency (GPS) band and the upper meander antenna with via hole connection is to contribute the higher frequency (K-PCS) band. In order to lowering the resonant frequency for GPS band, two printed modified meander antenna with gap stub is used to integrate with PCS band operation. The measured resonant frequency at GPS band shifts to lower frequency about 100MHz. The measured impedance bandwidth(VSWR $\leq$ 2) are 55MHz and 120MHz at the resonant frequency. respectively.

• ETRI Journal
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• v.36 no.3
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• pp.510-513
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• 2014

A Q-band pHEMT image-rejection low-noise amplifier (IR-LNA) is presented using inter-stage tunable resonators. The inter-stage L-C resonators can maximize an image rejection by functioning as inter-stage matching circuits at an operating frequency ($F_{OP}$) and short circuits at an image frequency ($F_{IM}$). In addition, it also brings more wideband image rejection than conventional notch filters. Moreover, tunable varactors in L-C resonators not only compensate for the mismatch of an image frequency induced by the process variation or model error but can also change the image frequency according to a required RF frequency. The implemented pHEMT IR-LNA shows 54.3 dB maximum image rejection ratio (IRR). By changing the varactor bias, the image frequency shifts from 27 GHz to 37 GHz with over 40 dB IRR, a 19.1 dB to 17.6 dB peak gain, and 3.2 dB to 4.3 dB noise figure. To the best of the authors' knowledge, it shows the highest IRR and $F_{IM}/F_{OP}$ of the reported millimeter/quasi-millimeter wave IR-LNAs.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.18-19
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• 2002

1950년 Norman Ramsy는 시간적으로 분리된 두 진동 자장을 사용한 마이크로파 전이 방법을 개발했다 이 방법을 사용할 경우 그림1과 같이 넓은 선폭을 가지는 공진선 ("Rabi pedestal") 위에 좁은 선폭의 분광 신호("Ramsey fringe")를 얻을 수 있다. 램지 방법은 정밀한 분광 측정에 많이 사용되고 있으며, 특히 원자 시계를 구현하기 위한 기본 기술이 되고 있다. (중략)

• Journal of the Semiconductor & Display Technology
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• v.8 no.4
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• pp.21-24
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• 2009

We investigated a nanoscale inertia sensor based on telescoping carbon nanotubes, using classical molecular dynamics simulations. The position of the telescoping nanotubes is controlled by the centrifugal force exerted by the rotation platform, thus, position shifts are determined by the capacitance between carbon nanotubes and the electrode, and the operating frequency of the carbon nanotube oscillator. This measurement system, tracking oscillations of the carbon nanotube oscillator, can be used as the sensor for numerous types of devices, such as motion detectors, accelerometers and acoustic sensors.

• Journal of the Korean Vacuum Society
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• v.5 no.1
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• pp.33-38
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• 1996

The induced linewidth, frequency shift and absorption spectrum for a molecular dipole in the vicinity of a phase -conjugate mirror have been investgated within a classical phenomenological model, with particularreference to the technique of optical phase conjugation by a surface. While the shifts and the widths show similar characteristics as those obtained recently by Bochove who considered the problem within the context of four-wave mixing, the results obtained in the present model can be defined uniquely with the possibility of an infinite lifetime for the excited admolecule . Furthermore, the absorption lineshape obtained here some interesting features which depend on both the magnitude and the phase of the complex reflectivity of the mirror.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2606-2609
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• 2001

We propose a robust channel equalization algorithm. which is called a 1-tap additional coefficient decision feedback equalizer(ACDFE), to improve the Doppler shift performance for the OFDM receiver. The algorithm is based on the frequency domain DFE with additional coefficients which are independent of the OFDM subcarriers. Test results on OFDM-16QAM signals confirm that the proposed ACDFE is robust against fading channel due to Doppler shifts and outperforms the conventional DFE in terms of SER, MSE, and convergence speed.

• Sleep Medicine and Psychophysiology
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• v.7 no.2
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• pp.96-101
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• 2000

Objectives: Through comparing sleep variables and autonomic activities among three shifts in shift workers, the authors intended to clarify which shift is most tolerable and to identify the characteristics of their psychological and physical problems. This study is also expected to help shift workers to adapt themselves to their work more effectively. Methods: Fifty one shift workers took part in this study. They were working in a rapidly rotating system in which they worked for 3 days in one shift with one day off between each shift. Based on a sleep diary, sleep latency (SL), sleep period time (SPT), and number of wake after sleep onset (NWASO) were estimated and compared among the three shifts. In assessing sleepiness, Epworth sleepiness scale (ESS) and visual analogue scale (VAS) were used. To evaluate mood states among the three shifts, profile of mood states (POMS) was administered. Heart rate variability (HRV), and the level of adrenaline and noradrenaline were measured to assess autonomic activities. HRV included low frequency power (LF), high frequency power (HF), and LF/HF. Results: SPT was significantly lengthened during the evening shift and SL was shortened during the night shift. The workers showed a drop in alertness at wake-up during morning shift and a drop in alertness at work during night shift. During night shift the subjects complained of physical fatigue and cognitive decline. Comparison of HRV showed that parasympathetic activity was most prominent during the evening shift. Secretion of adrenaline and noradrenaline decreased during the evening shift, though statistically not significant. Conclusion: We found that the evening shift was most tolerable among the three shifts. It is recommended that morning light exposure be done during the morning shift and nocturnal light exposure during the night shift.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.803-809
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• 2009

Notable blue shifts of the ν2 $C{\equiv}N$ stretching, $_{v4}$ C-C stretching and $_{v8}$ CCN deformation bands of $CD_3CN$ are observed upon solvation of $InCl_3$, resulting from the donor-acceptor interaction. The Raman spectrum in the $_{v2}$ region shows further details; at least two new bands emerge on the blue side of the $_{v2}$ band of free $CD_3CN$, whose relative intensities vary with concentration, suggesting that there exist at least two different cationic species in the solution. The strong hydrogen bonds formed between the methyl group and ${InCl_4}^-$ result in a large band appearing on the red side of the ν1 $CD_3$ symmetric stretching band. The solvation number of $InCl_3$, determined from the Raman intensities of the $C{\equiv}N$ stretching bands for free and coordinated $CD_3CN$, increases from $\sim$1.5 to $\sim$1.8 with decreasing concentration.