• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.794-797
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• 2014

스마트 디바이스의 사용량 증가와 더불어 각종 가전기기의 스마트화로 인하여 임베디드 시스템에서 주로 사용되는 SQLite 데이터베이스에 대한 동시적 접근 제어의 중요성이 증가하였다. 플래시 메모리 저장장치 단계에서 트랜잭션의 원자성올 제공하는 X-FTL 은 SQLite 의 저널링 모드에서 발생하는 쓰기 연산으로 인한 성능 저하를 해결하였다. 또한 페이지 단위로 트랜잭션의 원자성을 관리하는 X-FTL 의 특징을 이용한다면 동시성 제어 측면의 성능 향상을 기대할 수 있다. 본 논문에서는 X-FTL 을 사용할 때 발생할 수 있는 동시성 제어 성능의 한계를 밝히고, X-FTL 의 X-L2P 테이블에 SCN 을 추가하여 SQLite 의 동시성 제어 성능을 향상할 수 있는 새로운 구조를 제안한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.200-200
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• 2009

아크이온플래이팅 기술과 DC 마그네트론 스퍼터링 기술이 결합된 하이브리드 코팅 시스템을 이용하여 STS 304와 Si 기판에 4성분계 CrAlCxN1-x 코팅을 증착하였다. 합성된 CrAlCxN1-x 코팅은 주로 유도결합형로 f구성되었다. CrAlCxN1-x 코팅의 carbon 함량이 0.17 at.%일 때 약 34 GPa을 나타내었으며 마찰계수는 carbon 함량이 0에서 1 at.%로 증가함에 따라 0.82에서 0.38까지 크게 감소하였다. 이는 코팅 표면과 steel 볼 사이에 amorphous carbon layer가 형성되어 고체윤활제로 작용한 것으로 사료된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1711-1717
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• 2020

X-ray of up to 9MeV are used for container inspection. X-ray intensity must be maintained stably regardless of changes in time. If dose is not constant, it may affect the image quality, and as a result, may affect the inspection of abnormal cargo. Therefore, to acquire high-quality images, continuous dose monitoring is required. In this study, the ion-chamber based device was developed for monitoring the dose change in high-energy x-ray. And to estimate the performance of signal-processing device change according to the environmental change, the output changing due to the change of temperature and humidity was observed. In addition, verification of the device was performed by measuring the output change. As a result of the measurement, there was no significant difference in performance due to changes in temperature and humidity, and the change in output according to the change in exposure was linear. Therefore, it was found that the developed device is suitable for the dose monitoring of high-energy x-ray.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.333-333
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• 2012

III-V 족 화합물 반도체 물질인 $InAs_xP_{1-x}$는 다양한 광전자 소자와 빠른 속도의 전자 소자로써의 사용 가능성으로 각광받고 있다. 이러한 $InAs_xP_{1-x}$를 소자 제작에 이용하기 위해서는 임의의 As 함량에 따른 InAsP 물질의 정확한 광학적 특성 분석이 필요하다. 따라서 본 연구에서는 1.5~6.0 eV 에너지 구간에서 $InAs_xP_{1-x}$ ($0{\leq}{\times}{\leq}1$) 화합물의 임의의 As 함량에 따른 유전함수를 보고하고자 한다. MBE (molecular beam epitaxy)를 이용하여 InP 기판 위에 성장시킨 $InAs_xP_{1-x}$ (x = 0.000, 0.13, 0.40, 0.60, 0.80, 1.000) 박막을 타원편광분석법을 이용하여 측정하였고, 이 때 화학적 에칭을 통해 산화막 층을 제거하여 순수한 유전함수 ${\varepsilon}$을 얻을 수 있었다. 측정된 유전함수 분석은 parametric 모델을 이용하였으며, parametric 모델은 Gaussian-broadened polynomial들의 합으로서 반도체 물질의 유전함수를 정확히 기술하는 분석법이다. Parametric 모델을 통해 얻어진 각각의 변수들을 As 조성비 x에 대한 다항식으로 피팅하였고, 그 결과 임의의 조성비에 대한 $InAs_xP_{1-x}$ ($0{\leq}{times}{\leq}1$)의 유전함수를 얻어낼 수 있었다. 본 연구 결과는 물질의 실시간 성장 모니터링이나 다층구조 분석, 광소자의 제작 등에 유용한 정보로 이용될 수 있을 것이다.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.259-266
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• 2006

As the volume of spam has increased to extreme levels, many anti-spam filtering techniques have been proposed. Among these techniques, the machine-Loaming filtering technique is one of the most popular filtering techniques. In this paper, we propose a machine-learning spam filtering technique based on the neural network, the genetic algorithm and the $X^2$-statistic. This proposed filtering technique is designed to overcome the problems in existing filtering techniques, and to achieve high spam filtering accuracy. It is able to classify spam and legitimate emil with 95.25 percent and 95.31 percent accuracy. This accuracy of the sum filtering is 7.75 percent and the 12.44 percent higher than rule-based filtering and the Bayesian filtering technique, respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.77-81
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• 2007

We sputtered $TiN_x$ (titanium nitride) thin films on silicon substrates using ultra high vacuum RF magnetron sputtering method, and measured spectra of ellipsometry angles ${\Delta}$ and ${\Psi}$ in the photon-energy range of 1.5-5.0 eV using a variable angle spectroscopic ellipsometer. The optical constants, refractive index and extinction coefficient of the $TiN_x$ films were determined via the dispersion parameters extracted from the curve-fitting process based on Drude+Lorentz oscillator dispersion function. The reliability of determined optical constants were verified through the comparison of between simulated reflectance and reflectance spectra measured using a spectrophotometer.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.153-158
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• 2021

X-ray image analysis is a very important field to improve the early diagnosis rate and prediction accuracy of periodontal disease. Research on the development and application of artificial intelligence-based algorithms to improve the quality of such dental X-ray images is being widely conducted worldwide. Thus, the aim of this study was to design a super-resolution algorithm for predicting periodontal disease and to evaluate its applicability in dental X-ray images. The super-resolution algorithm was constructed based on the convolution layer and ReLU, and an image obtained by up-sampling a low-resolution image by 2 times was used as an input data. Also, 1,500 dental X-ray data used for deep learning training were used. Quantitative evaluation of images used root mean square error and structural similarity, which are factors that can measure similarity through comparison of two images. In addition, the recently developed no-reference based natural image quality evaluator and blind/referenceless image spatial quality evaluator were additionally analyzed. According to the results, we confirmed that the average similarity and no-reference-based evaluation values were improved by 1.86 and 2.14 times, respectively, compared to the existing bicubic-based upsampling method when the proposed method was used. In conclusion, the super-resolution algorithm for predicting periodontal disease proved useful in dental X-ray images, and it is expected to be highly applicable in various fields in the future.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.42-48
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• 1992

RoA is an important figure of merits for estimating the performance of p-n junction infrared detectors. This paper presents the tunneling current contribution to RoA of $Hg_{1-x}Cd_{x}$Te n$^{+}$-p juction photodiodes. Then, a diffusion model, a thermal generation-recombination model, an indirect tunneling model via trap, and a band-to-band direct tunneling model are considered to calculate RoA. Using these models, RoA depending on temperature, doping concentration, and mole fraction is calculated. Also from these results, under various operating conditions the dominant dark current mechanisms cna be understood.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.187-188
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• 2012

magnetron-sputtering법을 사용하여 $Cr_{1-x}Al_xN$ 박막을 증착함에 있어 Al 함량의 변화를 주었다. 그 후 열처리를 통하여 thermal inkjet 방식 print head의 heater resistor 소재로서의 특성 향상을 도모하였다. Al의 함량이 증가할수록 결정구조는 NaCl에서 wurtzite HCP 구조로 변화하였으며 전기적 특성 또한 다르게 나타났다. 비열처리 시 Al 함량이 클수록 결정성은 떨어진다는 것을 확인하였고, 열처리 시 Al 함량이 적을 수 록 더 안정한 온도 저항 계수를 나타내는 것을 확인하였다.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.55-58
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• 2002

The possibility of SnCuX Solder as alternative for Pb-free Solder have been investigated in this study. SnCuX Solder balls(500${\mu}{\textrm}{m}$) were placed on Si-wafer which is Al/Ni/Cu(500nm/$4{\mu}{\textrm}{m}$/$4{\mu}{\textrm}{m}$)UBM layer. After reflow soldering at $250^{\circ}C$, shear strength and microstructure were analyzed. The results showed that the shear strength(500gf) of SnCuX was higher than that of SnCuX at $230^{\circ}C$ and $Cu_6Sn_5$ intermetallic compounds were formed between Cu and SnCuX Solder layers