• 대한화학회지
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• 제40권6호
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• pp.415-419
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• 1996

수소결합, 유전효과 그리고 입체효과는 케톤의 카르보닐 신축진동을 결정하는 요인이 된다. 케톤의 카르보닐 신축진동은 다양한 용매에서 케톤의 농도변화에 영향을 받는다. 비극성용매에서 카르보닐 신축진동은 케톤의 부피%가 증가함에 따라 낮은 파수로 이동하고 극성용매에서는 높은 파수로 이동한다. 용매 아세토니트릴에서 카르보닐 신축진동은 dimethyl ketone을 제외하고 케톤의 부피%가 증가함에 따라 높은 파수로 이동한다. 용매의 극성이 증가할수록 카르보닐 신축진동은 낮은 파수로 이동하고 혼합용매 $CHCI_3CCI_4$에서 부피%가 증가할수록 낮은 파수로 이동한다.

• 한국지능시스템학회논문지
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• 제11권7호
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• pp.628-632
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• 2001

We propose time-frequency (TF) tools for analyzing linear time-varying (LTV) systems and nonstationary random processes. Obtained warping the narrowband Weyl symbol (WS) and spreading function (SF), the new TF tools are useful for analyzing LTV systems and random processes characterized by generalized frequency shifts, This new Weyl symbol (WS) is useful in wideband signal analysis. We also propose WS an tools for analyzing systems which produce dispersive frequency shifts on the signal. We obtain these generalized, frequency-shift covariant WS by warping conventional, narrowband WS. Using the new, generalized WS, we provide a formulation for the Weyl correspondence for linear systems with instantaneous of linear signal transformation as weighted superpositions of non-linear frequency shifts on the signal. Application examples in signal and detection demonstrate the advantages of our new results.

• Structural Engineering and Mechanics
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• 제41권6호
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• pp.751-758
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• 2012

We study thickness-shear (TSh) free vibrations of an unbounded, laminated elastic plate with three layers of different materials. One of the two interfaces is slightly weakened as described by the shear-lag model that allows the displacement to be discontinuous across the interface. A frequency equation is obtained from the linear theory of elasticity. A perturbation solution of the frequency equation is obtained from which the frequency shifts of TSh modes due to the weakened interface can be calculated. It is shown that the frequency shifts of TSh modes of different orders are different, and they satisfy different conditions when different interfaces are weakened. These conditions are obtained which can potentially be used as criteria for determining specifically which interface is weakened.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.725-729
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• 2007

We present calculations for the acetonitrile - water clusters to examine the nature of interactions in the mixed clusters. We calculate conformers of various composition, either of σ -type (-OH and -CN binding linearly) or π -type (-OH and -CN interacting perpendicularly) structures for the acetonitrile - water clusters. We predict that the IR frequency of the proton-accepting C≡N stretching mode red-shifts in the σ -type clusters and blueshifts in π -type conformers, whereas the proton-donating ?OH stretching frequency red-shifts in all cases. We find that this intriguing pattern also applies to the acetonitrile - water clusters of various molar ratio.

• 대한화학회지
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• 제17권4호
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• pp.240-246
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• 1973

분자 혹은 원자간의 충돌에 의한 light scattering의 강도를 계산하는 이론식을 유도하였다. Argon을 예로하여 적은 진동수 shift에 나타나는 좁은 분광 band는 원자간의 장거리 효과가 이방성에 미치는 영향에 의한 것이고 큰 진동수 shift에서의 넓은 분광 band는 단거리 효과에 의한 것임을 지적하였다.

• 약학회지
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• 제33권3호
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• pp.203-205
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• 1989

A method is presented for calculating the $^{13}C$ chemical shifts produced in liquid solution by referenced relative to RF frequency. The method is useful to get the real variations of chemical shifts in magnetic field by eliminating the affects of the variation of a reference substance.

• 반도체디스플레이기술학회지
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• 제19권4호
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• pp.88-93
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• 2020

Based on the capture-emission energy (CEE) maps of CMOS devices, a physics-informed machine learning model for the bias temperature instability (BTI)-induced threshold voltage shifts and low frequency noise is presented. In order to incorporate physics theories into the machine learning model, the integration of artificial neural network (IANN) is employed for the computation of the threshold voltage shifts and low frequency noise. The model combines the computational efficiency of IANN with the optimal estimation of Gaussian mixture model (GMM) with soft clustering. It enables full lifetime prediction of BTI under various stress and recovery conditions and provides accurate prediction of the dynamic behavior of the original measured data.

• Annals of Occupational and Environmental Medicine
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• 제34권
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• pp.36.1-36.12
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• 2022

Background: Many studies have been conducted to investigate the harmful effect of shift work on physical and mental health. Although, by definition, "working evening shift" is included in the scope of shift work, most related studies conducted thus far have focused on working night shifts, overtime work, or different types of shift work, with little research effort dedicated to "working evening shifts." Therefore, to fill this research gap, we investigated the effect of working evening shifts on workers' mental health. Methods: The participants of this study were 16,692 employees of the 50,205 that participated in the 5th wave of the Korean Working Conditions Survey. We performed χ² test and logistic regression analysis to analyze the effects of independent variables on health problems and calculated odds ratios and 95% confidence intervals (CIs). Results: In the logistic regression analysis adjusted for sociodemographic characteristics, health-related factors, and work-related characteristics, employees who worked evening shifts showed higher levels of depression and anxiety compared to those that did not. In particular, the adjusted odds ratios of the group working evening shifts between one and nine times a month were the highest with 2.723 (95% CI: 2.014-3.682) for depression, 3.294 (95% CI: 2.547-4.259) for anxiety. Conclusions: The results of our study suggest that working evening shifts has a negative effect on employees' mental health. This trend decreased with an increase in the monthly frequency of evening work.

• 한국지능시스템학회논문지
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• 제11권6호
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• pp.563-567
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• 2001

We generalize the widebane P0-weyl symbol (P0WS) and the widebane spreading function (WSF) using the generalized warping function . The new generalized P0WS and WSF are useful for analyzing system and communication channels producing generalized time shifts. We also investigated the relationship between the affine Wey1 symbol(AWS) and the P0WS. By using specific warping functions, we derive new P0WS and WSF as analysis tools for systems and communication channels with non-linear group delary characteristics. The new P0WS preserves specific types of changes imposed on random processes. The new WSF provides a new interpretation of output of system and communication channel as weighted superpositions of non-linear time shifts on the input. It is compared to the conventional method obtaining output of system and communication channel as a convention integration of the input with the impulse response of the system and the communication channel. The convolution integration can be interpreted as weighted superpositions of liner time shifts on the input where the weight is the impulse response of the system and the communication channel. Application examples in analysis and detection demonstrate the advantages of our new results.

• 한국전자파학회지:전자파기술
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• 제4권2호
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• pp.41-47
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• 1993

MnZn계 페라이트 실리콘 고무 복합체를 MnZn 페라이트의 체적비플 0.1에서 0.4까지 변화시키면서 제작하여 주파수 대역 1 GHz-lO GHz 범위에서 전기적 특성및 전파흡수 특성을 조사하였다. MnZn 페라이트의 체적비가 증가할 수록 유전율과 투자율의 증가를 보였다 반사 손실 흡수체의 두께가 1/4파장에 해당하는 주파수 대역에서 극대치가 나타났으며, 극대치는 MnZn 페라이트의 체적비가 증기할 수록 저주파 수로 이동하는 현상을 나타내었다 또한 흡수체의 두께가증가함에 따라서 반사손실 극대치는 저주파수 대역으로 안동하였다 페라이트 고무 복합체의 경우에 전파 흡수체의 사용주파수 대역에 따라서 요구되는 전파 흡수 효과를 얻기 위해서는 페라이트 체적비를 조절해야 함을 보여 주였다.