• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.131-131
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• 2010

The power of semiconductor laser diodes has been limited primarily by the heating effects which occur at high optical intensities. The actual limiting event can take one of a number of forms such as. catastrophic optical damage or filamentation. A general approach to this problem is to design a heterostructure which creates a high powered output while maintaining low internal optical intensities. A graded index separate confinement heterostructure (GRIN-SCH) is one such structure that accomplishes the above task. Here, the active region is sandwiched between graded index layers where the index of refraction increases nearer to the active layer. This structure has been shown to yield a high efficiency due to the confinement of both the optical power and carriers, thereby reducing the optical intensity required to achieve higher powers. The optical confinement also reinforces the optical beam quality against high power effects. Quantum dots have long been a desirable option for laser diodes due to the enhanced optical properties associated with the zeroth dimensionality. In our work, we use PICS3D software created by Crosslight Software Inc. to simulate the performance of In0.67A10.33As/A10.2Ga0.8AsquantumdotsusedwithaGRIN-SCH. The simulation tools are used to optimize the GRIN-SCH structure for high efficiency and optical beam quality.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.9-21
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• 2020

The aim of this paper is to predict the Borsa Istanbul (BIST) 30 index movements to determine the most accurate buy and sell decisions using the methods of Artificial Neural Networks (ANN) and Genetic Algorithm (GA). We combined these two methods to obtain a hybrid intelligence method, which we apply. In the financial markets, over 100 technical indicators can be used. However, several of them are preferred by analysts. In this study, we employed nine of these technical indicators. They are moving average convergence divergence (MACD), relative strength index (RSI), commodity channel index (CCI), momentum, directional movement index (DMI), stochastic oscillator, on-balance volume (OBV), average directional movement index (ADX), and simple moving averages (3-day moving average, 5-day moving average, 10-day moving average, 14-day moving average, 20-day moving average, 22-day moving average, 50-day moving average, 100-day moving average, 200-day moving average). In this regard, we combined these two techniques and obtained a hybrid intelligence method. By applying this hybrid model to each of these indicators, we forecast the movements of the Borsa Istanbul (BIST) 30 index. The experimental result indicates that our best proposed hybrid model has a successful forecast rate of 75%, which is higher than the single ANN or GA forecasting models.

• 디지털산업정보학회논문지
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• 제11권4호
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• pp.69-79
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• 2015

This research proposes a modified data hiding method to hide data in a slack space of an NTFS index record. The existing data hiding method is for anti-forensics, which uses traces of file names of an index entry in an index record when files are deleted in a direcotry. The proposed method in this paper modifies the existing method to make non-admittable ASCII characters for a file name applicable. By improving the existing method, problems of a file creation error due to non-admittable characters are remedied; including the non-admittable 9 characters (i. e. slash /, colon :, greater than >, less than <, question mark ?, back slash ${\backslash}$, vertical bar |, semi-colon ;, esterisk * ), reserved file names(i. e. CON, PRN, AUX, NUL, COM1~COM9, LPT1~LPT9) and two non-admittable characters for an ending character of the file name(i. e. space and dot). Two results of the two message with non-admittable ASCII characters by keyboard inputs show the applicability of the proposed method.

• 대한기계학회논문집B
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• 제30권4호
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• pp.287-297
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• 2006

The Holographic Particle Velocimetry system can be a promising optical tool for the measurements of three dimensional particle velocities. One of inherent limitations of particle holography is the very long depth of field of particle images, which causes considerable difficulty in the determination of particle positions in the optical axis. In this study, we introduced three auto-focusing parameters corresponding to the size of particles, namely, Correlation Coefficient, Sharpness Index, and Depth Intensity to determine the focal plane of a particle along the optical axis. To investigate the suitability of the above parameters, the plane image of dot array screens containing different size of dots was recorded by diffused illumination holography and the positions of each dot in the optical axis were evaluated. In addition, the effect of particle position from the holographic film was examined by changing the distance of the screen from the holographic film. All measurement results verified that the evaluated positions using suggested auto-focusing parameters remain within acceptable range of errors. These research results may provide fundamental information for the development of the holographic velocimetry system based on the automatic image processing.

• 한국광학회지
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• 제32권5호
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• pp.220-229
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• 2021

눈부심 방지를 위한 확산판의 투과율과 연색지수 향상을 위한 양자점 필름의 농도가 고출력 직하형 백색 LED 조명의 광특성에 미치는 영향을 조사했다. 확산판의 투과율이 감소할 경우 조명의 휘도는 줄어들었고 색좌표, 상관색온도는 별다른 변화를 보이지 않았으며 연색지수는 약간 상승했다. 시야각에 따른 광특성의 편차는 거의 없었고 휘도 분포는 람버시안 분포에 가까웠다. 양자점 필름의 농도가 증가할 경우 스펙트럼 상 적색 성분이 늘어나면서 이 성분의 비중을 표현하는 색좌표 x가 증가했고 상관색온도는 약 6000 K에서 4000 K 부근으로 현저히 감소했다. 아울러 조명의 구조를 최적화하면 연색지수가 95까지 증가함을 확인했다. 이런 결과는 적절한 투과율의 확산판과 양자점 필름의 조합을 통해 눈부심이 없고 시야각에 따른 색편차가 거의 없으며 특히 색좌표의 가변이 가능한 고연색성의 조명 구현이 가능함을 보여준다.

• 한국산업보건학회지
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• 제21권1호
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• pp.49-54
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• 2011

In order to develop the methods for exposure assessment and find susceptibility markers for the workers who are exposed to low doses of toluene, xylene and other chemical in petroleum industries, we investigated the application of P-450 expression in human lymphocytes utilizing mouse monoclonal anti-rat CYP2B1/2, the levels of toluene and xylene in air and their metabolite levels in urine with the levels of expressed CYP2B1/2 proteins. The general characteristics such as age, smoking and drinking habit were no significant difference between the control and exposed workers, but the working durations and working hours were significantly different. Workers in exposed group were exposed to the mean of 2.1 ppm (range, 0.00-4.54) of toluene and 0.3 ppm (rang, 0.00-1.23) of xylene. The mean concentration of urinary hippuric acid was low and less than 1/5 of the biological exposure index recommended by the Ministry of Employment and Labor Korea. Methyl hippuric acid in urine was not detected in control and exposed workers. Also, there were no significant differences in the levels of the urinary metabolites between the control and exposed group. When chemiluminescence dot blottings were carried out utilizing mouse monoclonal antibody against CYP2B1/2, the strong density dots corresponding to a mouse monoclonal antibody was observed in the human lymphocytes from the exposed workers. These results suggested that the chemiluminescence dot blot assay for CYP of lymphocytes should be valuable for identifying CYP expression as biomarkers in the workers exposed to toluene and xylene.

• Spatial Information Research
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• 제5권1호
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• pp.77-88
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• 1997

본 논문에서는 객체관계형 지리정보 시스템의 설계 및 구현에 대하여 논한다. 본 지리정보 시스템은 상용의 객체관계형 데이터베이스 시스템을 하부 구조로 사용하며, 객체지향 데이터 모델에 근거한 공간 객체모델, 공간 질의어 및 시각적 사용자 인터페이스를 제공하고 있다. 특히 본 시스템에서는 데이터베이스 상의 주색인(primary index)기법으로 적용 가능한 DOT 공간 색인 기법을 이용하여 효율적인 공간 질의 처리를 수행한다. 또한 본 시스템에서는 SDTS데이터 모델을 개념적 모델로 사용하며, SDTS의 공간 객체에 관한 개념적 모델은 지리정보 시스템 내에서 내부 데이터 모델인 객체지향 데이터 모델로 전환된다.

• 천문학회보
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• 제45권1호
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• pp.53.2-53.2
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• 2020

We measure X-ray timing and spectral properties of the pulsar PSR J0205+6449. Pulsar's rotation frequency ν = 15.20102357(9) s-1 and its derivative ${\dot{\nu}}=-4.5(1){\times}10^{-11}s^{-2}$ are measured, and the pulsed spectrum of 2-30 keV is model of power law with photon index ��psr = 1.07(16) and F2-30 keV = 7.3(6) × 10-13 erg cm-2 s-1. We use thermal emission models and non-thermal model to fit the pulsar spectrum and measure the surface temperature and luminosity of the pulsar. The surface temperature T∞ = 0.5-0.8 MK and luminosity Lth = 1-5 × 1032 erg s-1 are measure, and this result verifies the previous results known to have low surface temperature and luminosity for the age range of

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1795-1805
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• 2015

본 연구는 온라인 저널리즘의 추천기사가 대학생들의 뉴스기사 선택에 미치는 영향을 두 차원에서 분석하였다. 하나는 추천기사이고, 다른 하나는 이들 뉴스기사의 배치순위와 이용지수이다. 분석결과 11개의 추천기사 유형 중 7개 유형은 뉴스기사 선택에 긍정적인 영향을 미치는 것으로 나타난 반면, 4개 유형은 유의미하지 않은 것으로 나타났다. 뉴스기사 선택에 영향을 미치지 않은 것으로 나타난 추천기사 유형의 대부분은 댓글이나 SNS의 트윗과 관련된 것들이다. 또한 뉴스기사 및 검색어 배치순위는 뉴스기사 선택에 영향을 미치는 것으로 나타났으나 이용지수는 영향을 미치지 않은 것으로 나타났다. 한편, 뉴스기사 이용시간과 추천기사 유형 간 그리고 추천기사 유형 간 상관관계는 대부분 유의미한 것으로 나타났다. 분석결과를 종합하면, 뉴스기사 게재위치와 온라인 저널리즘의 추천기사와 같은 형식적 요인은 뉴스기사 헤드라인과 검색어 등의 내용과 더불어 뉴스 이용자들의 뉴스기사 선택에 긍정적인 영향을 미치는 것으로 결론지을 수 있다.

• 대한수학회지
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• 제55권2호
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• pp.373-390
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• 2018

In this paper we study the small-data scattering of the d dimensional fractional $Schr{\ddot{o}}dinger$ equations with d = 2, 3, $L{\acute{e}}vy$ index 1 < ${\alpha}$ < 2 and Hartree type nonlinearity $F(u)={\mu}({\mid}x{\mid}^{-{\gamma}}{\ast}{\mid}u{\mid}^2)u$ with max(${\alpha}$, ${\frac{2d}{2d-1}}$) < ${\gamma}{\leq}2$, ${\gamma}$ < d. This equation is scaling-critical in ${\dot{H}}^{s_c}$, $s_c={\frac{{\gamma}-{\alpha}}{2}}$. We show that the solution scatters in $H^{s,1}$ for any s > $s_c$, where $H^{s,1}$ is a space of Sobolev type taking in angular regularity with norm defined by ${\parallel}{\varphi}{\parallel}_{H^{s,1}}={\parallel}{\varphi}{\parallel}_{H^s}+{\parallel}{\nabla}_{{\mathbb{S}}{\varphi}}{\parallel}_{H^s}$. For this purpose we use the recently developed Strichartz estimate which is $L^2$-averaged on the unit sphere ${\mathbb{S}}^{d-1}$ and utilize $U^p-V^p$ space argument.