• Korean Journal of Materials Research
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• v.8 no.2
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• pp.165-172
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• 1998

Epitaxial ultrathin films of $CoSi_2$ and double heteroepitaxial structure of Si/$CoSi_2$/Si(lll) were prepared on Si(111)-$7\times{7}$ substrate by in situ solid-phase epitaxy in a ultrahigh vacuum(LHV). The phase, chemical composition, crystallinity, and the microsructure of the Si/$CoSi_2$/Si(lll) interface were investigated by 2-MeV $^4He^{++}$ ion backscattering spectrometry, X-ray diffraction, and high-resolution transmission electron microscopy. The growth mode of the Co film was the Stransky-Krastanov type with texture when the substrate temperature was room temperature. A-type $CoSi_2$ ultrathin film was grown by deposition of about 50A Co on Si(ll1)-$7\times{7}$ substrate followed by in situ annealing at $700^{\circ}C$ for 10 min. The matching face relationships were $CoSi_2$[110]//Si[110] and $CoSi_2$(002)//Si(002) with no misorientation angle. The A-type $CoSi_2$/Si(lll) interface was abrupt and coherent. The best epi-Si/epi-$CoSi_2$2(A-type)/Si(lll) structure was obtained by deposition of Si film on the CoSii at $500^{\circ}C$ followed by in situ annealing at $700^{\circ}C$ for 10 min in UHV.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.7 s.361
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• pp.105-111
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• 2007

In this paper, we designed and fabricated a 3-dB tandem coupler using air-bridge technology for millimeter-wane monolithic integrated circuits, operating at W-band($75{\sim}110\;GHz$) frequency. Tightly edge-coupled CPW line has low directivity due to different even-mode and odd-mode phase velocity. To overcome this disadvantage, a 3-dB tandem coupler which comprises the two-sectional weakly parallel-coupled lines with equal phase velocity was designed at W-band. The proposed coupler was fabricated using air-bridge technology to monolithically materialize the uniplanar coupler structure instead of conventional multilayer or wire bonded structure. From the measurements, the coupling coefficient of $2.9{\sim}3.6\;dB$ and the good phase difference of $91.2{\pm}2.9^{\circ}$ were obtained in broad frequency range of $75{\sim}100\;GHz$.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.119-125
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• 1990

This paper describes fiber optic voltage sensor using EOM-BSO (Electro-Optic Modulator-Bismuth Silicon Oxcide). Transceiver has an electical/optical converter and an optical/electrical converter which consist of light emitting diode, PIN-PD, and electronic circuits. Multimode fiber cable of $100/140{\mu}m$ core/clad diameter is used for connecting the transceiver to fiber cable and fiber optic voltage sensor. Before our experiments, by applying the Maxwell equations and wave equations, We derive matrix equation on wave propagation in the BSO single crystal. And also we derive optimal equation on intensity modulation arising through an analyzer. According to experi-mental results, fiber optic voltage sensor has maximum $2.5{\%}$ error within the applied AC voltage of 800V. As the applied voltage increases, saturation values of voltage sensor also increase. This phenomenon is caused by optical rotatory power of BSO single crystal. And temperature dependence of sensitivity for fiber optical rotatory power of BSO single crystal. And temperature dependence of sensitivity for fiber optic voltage sensor in the temperature range from$-20^{\circ}C\to\60^{\circ}C$ are measured within ${\pm}0.6{\%}$. And frequency characteristics of the voltage sensor has good frequency characteristics from DC to 100kHz.

• Journal of IKEEE
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• v.19 no.4
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• pp.596-602
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• 2015

In this paper, a unified inverse transformer is designed for HEVC and VP9. The proposed architecture performs all modes of HEVC and VP9 in the unified inverser transformer, such as $4{\times}4{\sim}32{\times}32$ HEVC IDCT, $4{\times}4$ HEVC IDST, $4{\times}4{\sim}32{\times}32$ VP9 IDCT, $4{\times}4{\sim}16{\times}16$ VP9 IADST and $4{\times}4$ IWHT. Same computations are used in HEVC IDCT and VP9 IDCT, except for the scales of the coefficients. Similarly, same computations are used in HEVC $4{\times}4$ IDST and VP9 $4{\times}4$ IADST, except for the scales of the coefficients. Furthermore, HEVC IDCT, VP9 IDCT, and VP9 IADST are the subsets of upper level IDCTs. The proposed architecture reuses multipliers when the computation is identical. Also it shares adders and butterfly structures even when the multiplier coefficients are different. So it reduces the hardware size significantly. Synthesized in 0.18 um technology, the gate count is 456,442 gates. which achieved 22.6% reduction compared to conventional architectures.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.385-393
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• 2009

The spectroscopic characteristics of Madagascar tourmaline were investigated by UV-Vis and FTIR spectroscopy. Physical features were similar to other region's tourmalines. The green and blue samples showed strong absorption band in the 714~743 nm due to $Fe^{3+}$, pink samples showed strong absorption band in the 510~530 nm due to $Mn^{3+}$, brown samples showed strong absorption at 324 nm due to $Mn^{2+}-Ti^{4+}$ IVCT and the colorless samples only revealed weak absorption at 406~413 nm or no absorptions due to low quantity of Mn. Combination of the stretching and bending mode cationic hydroxyl units (metal-OH) are observed in the 4300~4500 $cm^{-1}$. The parallel tube-shaped inclusions which contain hematite were detected generally. This investigation revealed that Cu was not detected but Fe and Mn were detected in the Madagascar tourmalines, and the various colors appear according to the amount of those impurity elements.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.311-316
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• 2019

The purpose of this study is to analyze the preference of haircut according to demographic factors such as age, education, marital status, occupation, monthly income, and residence in order to contribute to the establishment of hair trends of Korean women living in the 4th industrial age. Respectively. After the questionnaire was distributed, 305 questionnaires were analyzed statistically. According to the results of the questionnaire survey, it was found that the higher the age group was, the higher the gradation pattern was, and the difference was statistically different according to the demographic characteristics (p<0.05). By analyzing the shapes and differences of female haircuts according to these demographic characteristics, we will contribute to the establishment of sophisticated and innovative hair trends of Korean women living in the era of the fourth industrial revolution. Through this study, we can find the most ideal hairstyle for Korean women and it will be a starting point for development of various new and creative hairstyles. It is also used as basic data for hairdressing education and it will be actively used as an objective index that can express women 's personality clearly.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.30-39
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• 2022

Maintaining structural integrity of major apparatuses in a nuclear power plant, including piping system, is recognized as a critical safety issue. The integrity of piping system is also a critical matter related to the safety of a nuclear power plant. The actual failure mode of a piping system due to a seismic load is the leakage due to a fatigue crack, and the structural damage mechanism is the low-cycle fatigue due to large relative displacement that may cause plastic deformation. In this study, in-plane cyclic loading tests were conducted under various constant amplitudes using specimens composed of steel straight pipes and a steel pipe tee in the piping system of a nuclear power plant. The loading amplitude was increased to consider the relative displacement generated in the piping system under seismic loads, and the test was conducted until leakage, which is the limit state of the steel pipe tee, occurred due to fatigue cracks. The limit state of the steel pipe tee was expressed using a damage model based on the damage index that used the force-displacement relationship. As a result, it was confirmed that the limit state of the steel pipe tee can be quantitatively expressed using the damage index.

• Advanced Industrial SCIence
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• v.1 no.1
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• pp.7-15
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• 2022

To adopt the development in the medical scenario IoT developed towards the advancement with the processing of a large amount of medical data defined as an Internet of Medical Things (IoMT). The vast range of collected medical data is stored in the cloud in the structured manner to process the collected healthcare data. However, it is difficult to handle the huge volume of the healthcare data so it is necessary to develop an appropriate scheme for the healthcare structured data. In this paper, a machine learning mode for processing the structured heath care data collected from the IoMT is suggested. To process the vast range of healthcare data, this paper proposed an MTGPLSTM model for the processing of the medical data. The proposed model integrates the linear regression model for the processing of healthcare information. With the developed model outlier model is implemented based on the FinTech model for the evaluation and prediction of the COVID-19 healthcare dataset collected from the IoMT. The proposed MTGPLSTM model comprises of the regression model to predict and evaluate the planning scheme for the prevention of the infection spreading. The developed model performance is evaluated based on the consideration of the different classifiers such as LR, SVR, RFR, LSTM and the proposed MTGPLSTM model and the different size of data as 1GB, 2GB and 3GB is mainly concerned. The comparative analysis expressed that the proposed MTGPLSTM model achieves ~4% reduced MAPE and RMSE value for the worldwide data; in case of china minimal MAPE value of 0.97 is achieved which is ~ 6% minimal than the existing classifier leads.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.454-464
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• 2023

This paper proposes a low-power 8-bit asynchronous SAR ADC with a sampling rate of 1 MS/s for sensor node applications. The ADC uses bootstrapped switches to improve linearity and applies a VCM-based CDAC switching technique to reduce the power consumption and area of the DAC. Conventional synchronous SAR ADCs that operate in synchronization with an external clock suffer from high power consumption due to the use of a clock faster than the sampling rate, which can be overcome by using an asynchronous SAR ADC structure that handles internal comparisons in an asynchronous manner. In addition, the SAR logic is designed using dynamic logic circuits to reduce the large digital power consumption that occurs in low resolution ADC designs. The proposed ADC was simulated in a 180-nm CMOS process, and at a 1.8 V supply voltage and a sampling rate of 1 MS/s, it consumed 46.06 𝜇W of power, achieved an SNDR of 49.76 dB and an ENOB of 7.9738 bits, and obtained a FoM of 183.2 fJ/conv-step. The simulated DNL and INL are +0.186/-0.157 LSB and +0.111/-0.169 LSB.

• Korean Journal of Optics and Photonics
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• v.18 no.5
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• pp.351-361
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• 2007

The samples composed of a GST thin film and the protective layers of $ZnS-SiO_2$ or $Al_2O_3$ coated on c-Si substrate were prepared by using the magnetron sputtering method. Samples of three different structures were prepared, that is, i) the GST single film on c-Si substrate, ii) the GST film sandwiched by the protective $ZnS-SiO_2$ layers on c-Si substrate, and iii) the GST film sandwiched by $Al_2O_3$ protective layers on c-Si substrate. The ellipsometric constants in the temperature range from room temperature to $700^{\circ}C$ were obtained by using the in-situ ellipsometer equipped with a conventional heating chamber. The measured ellipsometric constants show strong variations versus temperature. The variation of ellipsometric constants at the temperature region higher than $300^{\circ}C$ shows different behaviors as the ambient medium is changed from in air to in vacuum or the protective layers are changed from $ZnS-SiO_2$ to $Al_2O_3$. Since the long heating time of 1-2 hours is believed to be the origin of the high temperature variation of ellipsometric constants upon the heating environment and the protective layers, a PRAM (Phase-Change Random Access Memory) recorder is introduced to reduce the heating time drastically. By using the PRAM recorder, the GST samples are heated up to $700^{\circ}C$ decomposed preventing its partial evaporation or chemical reactions with adjacent protective layers. The surface image obtained by SEM and the surface micro-roughness verified by AFM also confirmed that samples prepared by the PRAM recorder have smoother surface than the samples prepared by using the conventional heater.