• Journal of the Korean institute of surface engineering
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• v.32 no.2
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• pp.93-99
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• 1999

Surface polymer layer formed on the silicon wafer during the oxide overetching using $C_4F_8$/ helicon wave plasmas and their characteristics were investigated using spectroscopic elipsometry, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry. Overetch percentage and dc-self bias voltage were varied to investigate the effects on the characteristics of the polymers remaining on the overetched silicon surface. The increase of bias voltage from -80 volts to -120 volts increased the C/F ratio and carbon bondings such as C-C, $C-CF_x$/, and C-Si in the polymer while reducing the thickness of the polymer layer. However, the increase of the overetch percentage from 50% to 100% did not change the composition of the polymer layer and the carbon bondings in the polymer layer remained same even though it increased the polymer thickness. The polymer layer formed at the higher dc-self bias voltage was more difficult to be removed by the following various post-etch treatments compared to that formed at the longer overetch percentage.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.05a
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• pp.19-20
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• 2013

Thermoelectic properties of the typical thermoelectric host materials, the tellurides and selenides, are known to be noticeably changed by their volume change due to the strain [1]. In the bismuth telluride ($Bi_2Te_3$) crystal, a substitution of rare-earth element by replacing one of the Bi atoms may cause the change of the lattice parameters while remaining the rhombohedral structure of the host material. Using the first-principles approach by the precise full potential linearized augmented plane wave (FLAPW) method [2], we investigated the Ce substitution effect on the thermoelectric transport coefficients for the bismuth telluride, employing Boltzmann's equation in a constant relaxation-time approach fed with the FLAPW wave-functions within the rigid band approximation. Depending on the real process of re-arrangement of atoms in the cell to reach the equilibrium state, $CeBiTe_3$ was found to manifest a metal or a narrow bandgap semiconductor. This feature along with the strong correlation effect originated by the 4f states of Ce affect significantly on the thermoelectric properties. We showed that the position of the strongly localized f-states in energy scale (Fig. 1, f-states are shaded) was found to alter critically the transport properties in this material suggesting an opportunity to improve the thermoelectric efficiency by tuning the external strain which may changing the location of the f-sates.

• Nuclear Engineering and Technology
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• v.14 no.1
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• pp.22-40
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• 1982

The nuclear LS-energy matrix elements have been calculated with the harmonic oscillator shell model wave functions for the configurations ( $l_{i}$ $l_{i+1}$｜ $l_{i}$ $l_{i+1}$) where 1$_1$= $l_{s}$ , $l_2$=lp, $l_3$=ld, 2s, $l_4$=1f, 2p, $l_{5}$ =1g, 2d, 3s. The resulting matrix elements are expressed in terms of both Talmi integrals $I_1$ and Slater integrals $F^{k}$ . In addition to this various sum rules are derived and applied to check the results of the calculations.ons.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.2
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• pp.112-121
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• 2011

The IEEE WAVE standard specification does not support handover operation since it is designed to transmit mainly the ITS-related messages that are limited in length. More advanced multimedia applications such as Internet browsing and streaming of video clips produced by CCTVs, however, require handover support such that a sequence of data packets can be received seamlessly while an OBU's association with the RSUs changes. This paper presents a new handover scheme that can operate without performance degradation in the cases where there are multiple RSUs in the areas of handover by making use of the IEEE 802.11f IAPP Move-notify messages, based on the fast handover scheme with proactive caching by disassociation messages introduced previously. Experimental results from the simulation shows that the proposed handover scheme outperforms the scheme based solely on multicast.

• Fashion & Textile Research Journal
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• v.6 no.4
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• pp.503-510
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• 2004

The study is one of fundamental researches for the development of future smart clothing and textile products with blocking properties from electromagnetic waves by analyzing human physical symptoms in using electromagnetic products in such an environments. Among various textiles in the experiment, nano silver has shown the best blocking performance from electromagnetic waves, which decreases depending on the distance. The power spectrum distribution and the incidence of electroencephalogram between blocking materials and aural stimuli has shown that, ${\beta}$, wave appeared to be active in all channels except for $T_4$, whereas all waves appeared with processed materials and especially with nano silver silk(NSS), ${\alpha}$, ${\beta}$, ${\theta}$, ${\gamma}$ waves appeared active in all regions. As for the brain mapping of ${\alpha}$ wave according to time, there found a strong activity in $P_3$, $P_4$ of the parietal lobe, with all materials on all time regions. With silk nylon metal(SNM) and NSS, it appeared strong in $F_3$, $F_4$ as well. As for ${\beta}$, wave, the activity appeared strong in frontal lobe before 7min. 30sec, where it tends to diminish abruptly in 7min. 30sec. to 13min. 30sec. region. After 13min., it regained gradually. With NSS, it appeared strong in all areas except for the farthest $T_4$. The appearance of ${\nu}$ wave can be deduced as it can affect human body with its toxic property while the silver particles become nano-sized. Therefore, the study conducted with human participants requires a proper particle size of it which would not penetrate cellular tissues and a proper binder and binding treatment for it, to prevent the physical fatigues and the potential diseases. However, it is highly required for back-up researches to verify various aspects in applying nano silver to textile products.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.2
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• pp.173-176
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• 2019

In this study, a Ka-band waveguide rotary joint that can be applied to a millimeter-wave seeker is designed and fabricated. The proposed rotary joint maintains a low standing-wave ratio and low-loss characteristics, and has two rotary axes designed to enable azimuth and elevation rotation. The rotary joint is designed as a ridge-waveguide-type mode converter and a ${\lambda}/4$ choke structure to match the electromagnetic wave propagation mode between the spherical and circular waveguides. A performance test using a network analyzer and a high-power transmitter to assess vibration and shock were conducted. Results showed that the rotary joint had a very low standing-wave ratio of less than the maximum of 1.19:1 and an insertion loss of less than 0.80 dB at $F_C{\pm}500MHz$.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.3
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• pp.121-128
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• 2024

There are growing concerns that the recently implemented Earthquake Early Warning service is overestimating the rapidly provided earthquake magnitudes (M). As a result, the predicted damages unnecessarily activate earthquake protection systems for critical facilities and lifeline infrastructures that are far away. This study is conducted to improve the estimation accuracy of M by incorporating the observed S-wave seismograms in the near source region after removing the site effects of the seismograms in real time by filtering in the time domain. The ensemble of horizontal S-wave spectra from at least five seismograms without site effects is calculated and normalized to a hypocentric target distance (21.54 km) by using the distance attenuation model of Q(f)=348f^0.52 and a cross-over distance of 50 km. The natural logarithmic mean of the S-wave ensemble spectra is then fitted to Brune's source spectrum to obtain the best estimates for M and stress drop (SD) with the fitting weight of 1/standard deviation. The proposed methodology was tested on the 18 recent inland earthquakes in South Korea, and the condition of at least five records for the near-source region is sufficiently fulfilled at an epicentral distance of 30 km. The natural logarithmic standard deviation of the observed S-wave spectra of the ensemble was calculated to be 0.53 using records near the source for 1~10 Hz, compared to 0.42 using whole records. The result shows that the root-mean-square error of M and ln(SD) is approximately 0.17 and 0.6, respectively. This accuracy can provide a confidence interval of 0.4~2.3 of Peak Ground Acceleration values in the distant range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.2
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• pp.122-129
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• 2014

In this study, emotion-classification gathered from users was performed, classification-experiments were then conducted using SVM(Support Vector Machine) and K-means algorithm. Total 15 numbers of channels; CP6, Cz, FC2, T7. PO4, AF3, CP1, CP2, C3, F3, FC6, C4, Oz, T8 and F8 among 32 members of the channels measured were adapted in Brain signals which indicated obvious the classification of emotions in previous researches. To extract emotion, watching DVD and IAPS(International Affective Picture System) which is a way to stimulate with photos were applied and SAM(Self-Assessment Manikin) was used in emotion-classification to users' emotional conditions. The collected users' Brain-wave signals gathered had been pre-processing using FIR filter and artifacts(eye-blink) were then deleted by ICA(independence component Analysis) using. The data pre-processing were conveyed into frequency analysis for feature extraction through FFT. At last, the experiment was conducted suing classification algorithm; Although, K-means extracted 70% of results, SVM showed better accuracy which extracted 71.85% of results. Then, the results of previous researches adapted SVM were comparatively analyzed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.104-109
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• 2020

In this paper, we proposed a miniaturized folded inverted F antenna with ISM-band (center frequency : 447 MHz) for mounting in intelligent parking sensor. First, to mount the antenna in the intelligent parking sensor module (72 mm × 70 mm) with limited size, a folded inverted F antenna was designed at low frequency 447 MHz (wavelength λ : 670 mm) of the ISM-band. As a result, it resonates in the ISM band and obtains suitable characteristic with a -10 dB bandwidth of 13 MHz (2.9%). In addition, the H-plane pattern by the vertical and horizontal elements represents the omni-directional patterns from which the null point is removed, and the E-plane has directivity in a specific direction. Finally, it is suitable as and antenna for vehicle management in parking lots.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.842-845
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• 2005

A method for the numerical simulation of two-dimensional free-surface flow resulting from the propagation of regular gravity waves over topography with arbitrary bottom shape is presented. The method is based on the numerical solution of the Euler equations subject to the fully nonlinear free-surface boundary conditions and the appropriate bottom, inflow and outflow conditions using a hybrid finite-differences and spectral-method scheme. The formulation includes a boundary-fitted transformation, and is suitable for extension to incorporate large-eddy simulation (LES) and large-wave simulation (LWS) terms for turbulence and breaking wave modeling, respectively. Results are presented for the simulation of the free-surface flow over two different bottom topographies, with constant slope values of 1:10 and 1:20, two different inflow wave lengths and two different inflow wave heights. An absorption outflow zone is utilized and the results indicate minimum wave reflection from the outflow boundary. Over the bottom slope, lengths of waves in the linear regime are modified according to linear theory dispersion, while wave heights remain more or less unchanged. For waves in the nonlinear regime, wave lengths are becoming shorter, while the free surface elevation deviates from its initial sinusoidal shape.