• Journal of the Optical Society of Korea
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• 제20권4호
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• pp.524-529
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• 2016

Diagnostic sensors are demanded during plasma processes. Holograms of plasma taken with laser light without a reference beam were used to monitor behaviors of charged particles produced in nitrogen plasma as a function of electrode temperature ranging between 50 and 300℃. Holograms were characterized as a function of the pixel sum and grayscale value. Pixel sum calculated in identified grayscale ranges strongly correlated with ion density and emitted light intensity measured with a langmuir probe and optical emission spectroscopy, respectively. The performance was further evaluated with data acquired as a function of N₂ and NH₃ flow rates and improved correlations were observed in the new grayscale range. The confirmed correlations indicate that a hologram is a viable means to diagnose behaviors of plasma particles such as ions. Underlying principles are discussed in view of particle and charge composing vacuum and light.

• Asian Journal for Public Opinion Research
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• 제5권1호
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• pp.15-40
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• 2017

This paper addresses the zero-sum of soft power against the backdrop of the rise of China and the relative "decline" of America. It attempts to find out that whether the "decline" of America's soft power is caused by the rise of China's soft power, and whether China's rise could guarantee with certainty the growth of soft power. In light of the particularity of South Korea, that is, its economy relies on China and its security relies on the US, this paper chooses South Korea as the entry point for the study. Based on the Pew data from a South Korean opinion poll, this paper conducts bivariate correlation and binary logistic regression respectively, to explore the existence of zero-sum "competitions" between China's and America's soft power.

• Journal of Photoscience
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• 제11권1호
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• pp.35-40
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• 2004

[Ru(2,2'-bipyridine)$_2$(4,4'-dicarboxy-2,2'-bipyridine)]$^{2+}$(RuBDc) is a very photostable probe that possesses favorable photophysical properties including long lifetime, high quantum yield, large Stokes' shift, and highly polarized emission. To evaluate the usefulness of this luminophore (RuBDc) for studying macromolecular dynamics, its intensity and anisotropy decays when conjugated to RNA bacteriophage MS2 were examined using frequency-domain fluorometry with a high-intensity, blue light-emitting diode (LED) as the modulated light source. The intensity decays were best fit by a sum of two exponentials, and the mean intensity decay time was 442.2 ns. The anisotropy decay data showed a single rotational correlation time (2334.9 ns), which is typical for a spherical molecule. The use of RuBDc enabled us to measure the rotational correlation time up to several microseconds. These results indicate that RuBDc can be useful for studying rotational diffusion of biological macromolecules.s.

• Current Optics and Photonics
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• 제2권1호
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• pp.39-46
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• 2018

Visible-light communication (VLC) combined with advanced illumination can be expected to become an integral part of next-generation communication networks. One of the major concerns in VLC implementation is developing resource-allocation schemes in a multi-user scenario. However, the scheduling for heterogeneous quality of service (QoS) traffic has not been studied so far, for the indoor VLC downlink system. In this paper, we creatively introduce effective-bandwidth and effective-capacity theory into the multi-user scheduling (MUS) problem, to guarantee the user's statistical delay QoS. We also take account of the aggregate interference (AI) in the indoor VLC downlink system, and analyze its impact on the user-centric MUS problem for the first time. Simulations show that the AI has a nonnegligible influence on the scheduling result, and that the proposed scheduling scheme could guarantee the user's QoS requirement under the premise of ensuring sum capacity.

• 한국광학회지
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• 제9권4호
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• pp.245-250
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• 1998

본 논문에서는 백색광주사간섭무늬의 정점검출을 위한 새로운 디지털처리 알고리즘을 제안한다. 본 알고리즘은 백색광주사간섭무늬의 가시도함수를 이차의 다항식으로 가정하고, 측정된 광강도 값들을 최소자승법을 이용하여 직접적으로 곡선맞춤하여 가시도함수의 정점의 위치를 검출한다. 기존의 정점검출 알고리즘들과 비교하여, 본 이차다항식맞춤 알고리즘은 가시도함수의 추출을 위한 별도의 연산이 요구되지 않아 3N+29의 작은 곱셈 계산량만으로 연산을 완료 할 수 있다. 또한 최소자승법을 사용함으로써 간섭무늬가 갖는 외부 교란을 효과적으로 억제하여 안정된 해를 제공하는 장점을 갖는다.

• 한국경제지리학회지
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• 제20권3호
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• pp.369-387
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• 2017

본 연구는 DMSP 위성의 OLS 센서에서 촬영된 Stable Lights 영상자료로부터 랴오닝성과 단둥시의 빛합계 지수를 도출한 후 이 지표와 경제 수준 간 관계를 분석하였다. 랴오닝성의 빛합계 지수는 다른 성급 지역의 평균보다 높은 수준이었고, 지난 20여 년 동안 지속적인 증가 추세를 보였다. 실질 성장률과 1인당 평균 임금 등 이 지역의 경제 수준 향상을 지시하는 경제 지표 변화를 잘 반영한다고 볼 수 있다. 그러나 단둥시의 빛합계 지수는 다른 지급시 평균보다 낮은 수준이었는데, 이는 주요 경제 지표에 기초한 이 도시의 경제적 지위와 맥을 같이하는 것으로 보인다. 이전 시기에 비해 1998~2007년 사이 대북무역이 활성화된 단둥시 시할구의 빛합계 지수의 연간 증가율이 높아졌고, 비슷한 기간 동안 북중 교역액과 북한의 대중 수출액도 증가하는 패턴을 보였다. 이 기간 동안 햇볕정책의 영향으로 남 북한 간 긴장 관계가 완화되었던 것을 비추어볼 때, 빛합계 지수는 단둥시의 지정학 및 지경학의 특성을 설명할 수 있는 공간 대안 지표로 활용될 수 있을 것으로 기대된다.

• 대한전자공학회논문지
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• 제10권3호
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• pp.1-9
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• 1973

파일롯트 램프와 숫자표시를 목적으로 국내에서 처음으로 화합물반도체인 갈륨 인을 사용해서 발광다이오드를 만들었다. 이같이 만든 다이오드는 밝고 선명한 붉은 빛을 냈으며 발광하는데 필요한 순방향 바이아스 전류는 5mA 이하였다. 다이오드의 p-n 접합면은 n형 GaP 단결정 기판에 liquid phase epitaxy방법으로 성장시켰고 이때의 Ga 용액의 온도는 약 1300°K정도를 유지했다. 이렇게 하여 제조된 p-n 접합체에 wire bonding으로 ohmic contact시켜 다이오드를 제조했다. 칼륨인 발광다이오드는 매우 적은 전류로 발광되는 장점과 성장 반웅시 질소를 불순물로 doping시키면 녹색으로 발광되는 장점을 갖고 있으므로 앞으로 양산화의 전망이 매우 밝다.

• 대한수학회보
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• 제54권3호
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• pp.763-787
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• 2017

A graph is called 1-planar if it can be drawn in the Euclidean plane ${\mathbb{R}}^2$ such that each edge is crossed by at most one other edge. The weight of an edge is the sum of degrees of two ends. It is known that every planar graph of minimum degree ${\delta}{\geq}3$ has an edge with weight at most 13. In the present paper, we show the existence of edges with weight at most 25 in 3-connected 1-planar graphs.

• 천문학회보
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• 제36권2호
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• pp.129.1-129.1
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• 2011

We have applied an advanced multi-aperture indexing photometry and sophisticated de-trending method to existing Taiwanese-American Occultation Survey (TAOS) data sets. TAOS, a wide-field ($3^{\circ}{\times}3^{\circ}$) and rapid photometry (5Hz) survey, is designed to detect small objects in the Kuiper Belt. Since TAOS has fast and multiple exposures per zipper mode image, point spread function (PSF) varies in a given image. Selecting appropriate aperture among various size apertures allows us to reflect these variations in each light curve. The survey data turned out to contain various trends such as telescope vibration, CCD noise, and unstable local weather. We select multiple sets of stars using a hierarchical clustering algorithm in such a way that the light curves in each cluster show strong correlations between them. We then determine a primary trend (PT) per cluster using a weighted sum of the normalized light curves, and we use the constructed PTs to remove trends in individual light curves. After removing the trend, we can get each synthetic light curve of star that has much higher signal-to-noise ratio. We compare the efficiency of the synthetic light curves with the efficiency of light curves made by previous existing photometry pipelines. Our photometric method is able to restore subtle brightness variation that tends to be missed in conventional aperture photometric methods, and can be applied to other wide-field surveys suffering from PSF variations and trends. We are developing an analysis package for the next generation TAOS survey (TAOS II) based on the current experiments.

• Journal of the Optical Society of Korea
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• 제15권4호
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• pp.357-361
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• 2011

Photon-counting sensing is a widely used technique for low-light-level imaging applications. This paper proposes a distance information extraction method with photon-counting passive sensing under low-lightlevel conditions. The photo-counting passive sensing combined with integral imaging generates a photon-limited elemental image array. Maximum-likelihood estimation (MLE) is used to reconstruct the photon-limited image at certain depth levels. The distance information is extracted at the depth level that minimizes the sum of the standard deviation of the corresponding photo-events in the elemental image array. Experimental and simulation results confirm that the proposed method can extract the distance information of the object under low-light-level conditions.