• 대한환경공학회지
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• 제36권3호
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• pp.214-220
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• 2014

본 연구는 도광판의 간격이 Chlorella vulgaris (C. vulgaris)의 증식률에 미치는 영향을 알아보고자 하였다. C. vulgaris (FC-16) ($3-8{\mu}m$)는 Jaworski's Medium 에 $22^{\circ}C$에서 15일 증식시킨 뒤 사용하였다. 실험을 위하여 네 개의 샘플을(Run 1: 225 mm 간격, Run 2: 150 mm 간격, Run 3: 112.5 mm 간격, Run 4: 90 mm 간격) 준비하여 도광판의 간격이 C. vulgaris의 증식률에 미치는 영향을 비교 실험하였다. 광효율은 Run 1이 86%, Run 2가 90%, Run 3가 92% 그리고 Run 4가 94%의 광효율을 나타내어 도광판의 간격이 짧을수록 광효율은 높았으며, 도광판의 간격에 따라 Run 1은 7일째, Run 2는 5일째, Run 3는 3일째 그리고 Run 4는 2일째에 최대 바이오매스 증식률을 나타내었다. 또한, 최대 증식률은 Run 4가 Run 1에 비해 3배 높았다. 그러나, 증식속도, 셀 당 클로로필 함량 및 단위면적 당 Cell volume 그리고 Doubling time은 Run 1과 Run 2에 비해 Run 3와 Run 4가 높았지만 Run 3과 Run 4는 크게 차이가 없었다. 따라서 경제적인 부분을 고려한다면 바이오매스의 대량생산을 위하여 Run 3의 사용이 가장 효율적이라 생각된다. measured, and the results for the toxic effect was not observed.

• 대한핵의학회지
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• 제21권1호
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• pp.9-16
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• 1987

It is well-known that hepatic scintigraphv have been found to be less sensitive and specific in the detection of the diffuse hepatocellular diseases than that of the space-occupying lesions. To obtain the higher diagnostic specificity and sensitivity, we, using the computer quantitation, have attempted to analyze hepatic and extrahepatic $^{99m}Tc-tin$ colloid uptake patterns in various diffuse hepatocellular diseases retrospectively. The studied groups consisted of 116 cases of normal, 67 cases of acute hepatitis, 112 cases of chronic hepatitis, 61 cases of liver cirrhosis, 47 cases of fatty liver, 12 cases of hepatoma and 9 cases of metastasis, making total 424 cases. Scintigraphic imagings were obtained in the anterior, right lateral and posterior projections using high-resolution collimation, and simultaneously these gamma data were acquisited into the computer system. Both large region of interest (ROI) using light pen and ROI computer program were placed over right lobe, left lobe of liver, spleen and cardiac blood pool. Total counts in ROI were divided by the number of pixels in the ROI, and mean count rate per pixels calculated. Mean right-lobe counts were divded by mean-left lobe counts to determine right-to-left hepatic lobe ratio and mean spleen counts were divided by mean liver counts to determine spleen to liver ratio. The results were as follows. 1) Of 424 cases, 292 were male and 132 were female. The majority of age distribution was in $30\sim49$ (54.5%). 2) Inter-observer between two independant operators and inter-method between drawing by light-pen and ROI computer program variations were not significant. 3) The uptake count values (per pixel) determined at each area in normal group were $106.53{\pm}18.35$ in right lobe, $79.00{\pm}13.82$ in left lobe, $17.52{\pm}8.31$ in spleen and $8.09{\pm}3.43$ in cardiac blood pool. 4) In liver cirrhosis, right lobe uptake was decreased but spleen and cardiac blood pool uptakes were increased (p<0.01). 5) Right-to-left hepatic lobe uptake ratio was $1.37{\pm}0.24$ in normal group and significantly low in chronic hepatitis, liver cirrhosis and fatty liver, and more or less low in acute hepatitis. 6) Spleen-to-right hepatic lobe uptake ratio was $0.17{\pm}0.09$ in normal group and high in chronic hepatitis and liver cirrhosis. 7) The computer-quantitation of hepatic and extrahepatic uptake patterns thought to be sensitive and useful method in the interpretation of liver scintigram.

• 한국재료학회지
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• 제21권10호
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• pp.573-579
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• 2011

Highly textured Ag, Al and Al:Si back reflectors for flexible n-i-p silicon thin-film solar cells were prepared on 100-${\mu}m$-thick stainless steel substrates by DC magnetron sputtering and the influence of their surface textures on the light-scattering properties were investigated. The surface texture of the metal back reflectors was influenced by the increased grain size and by the bimodal distribution that arose due to the abnormal grain growth at elevated deposition temperatures. This can be explained by the structure zone model (SZM). With an increase in the deposition temperatures from room temperature to $500^{\circ}C$, the surface roughness of the Al:Si films increased from 11 nm to 95 nm, whereas that of the pure Ag films increased from 6 nm to 47 nm at the same deposition temperature. Although Al:Si back reflectors with larger surface feature dimensions than pure Ag can be fabricated at lower deposition temperatures due to the lower melting point and the Si impurity drag effect, they show poor total and diffuse reflectance, resulting from the low reflectivity and reflection loss on the textured surface. For a further improvement of the light-trapping efficiency in solar cells, a new type of back reflector consisting of Ag/Al:Si bilayer is suggested. The surface morphology and reflectance of this reflector are closely dependent on the Al:Si bottom layer and the Ag top layer. The relationship between the surface topography and the light-scattering properties of the bilayer back reflectors is also reported in this paper.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.2089-2092
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• 2007

Tantalum-containing metal oxides, well known for their efficiency in water splitting and H2 production, have never been used in visible light driven photodecomposition of H2S and H2 production. The present work is an attempt in this direction and investigates their efficiency. A mixed metal oxide, ZnFe2Ta2O9, with the inclusion of Fe2O3 to impart color, was prepared by the conventional ceramic route in single- and double-calcinations (represented as ZnFe2Ta2O9-SC and ZnFe2Ta2O9-DC respectively). The XRD characterization shows that both have identical patterns and reveals tetragonal structure to a major extent and a minor contribution of orthorhombic crystalline system. The UV-visible diffuse reflection spectra demonstrate the intense, coherent and wide absorption of visible light by both the catalysts, with absorption edge at 650 nm, giving rise to a band gap of 1.9 eV. Between the two catalysts, however, ZnFe2Ta2O9-DC has greater absorption in almost the entire wavelength region, which accounts for its strong brown coloration than ZnFe2Ta2O9-SC when viewed by the naked eye. In photocatalysis, both catalysts decompose H2S under visible light irradiation (λ ≥ 420 nm) and produce solar H2 at a much higher rate than previously reported catalysts. Nevertheless, ZnFe2Ta2O9-DC distinguishes itself from ZnFe2Ta2O9-SC by exhibiting a higher efficiency because of its greater light absorption. Altogether, the tantalum-containing mixed metal oxide proves its efficient catalytic role in H2S decomposition and H2 production process also.

• 농업과학연구
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• 제39권3호
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• pp.407-412
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• 2012

Soil texture has an important influence on agriculture such as crop selection, movement of nutrient and water, soil electrical conductivity, and crop growth. Conventionally, soil texture has been determined in the laboratory using pipette and hydrometer methods requiring significant amount of time, labor, and cost. Recently, in-situ soil texture classification systems using optical diffuse reflectometry or mechanical resistance have been reported, especially for precision agriculture that needs more data than conventional agriculture. This paper is a part of overall research to develop an in-situ soil texture classification system using image processing. Issues investigated in this study were effects of sensor travel speed and light source and intensity on image quality. When travel speed of image sensor increased from 0 to 10 mm/s, travel distance and number of pixel were increased to 3.30 mm and 9.4, respectively. This travel distances were not negligible even at a speed of 2 mm/s (i.e., 0.66 mm and 1.4), and image degradation was significant. Tests for effects of illumination intensity showed that 7 to 11 Lux seemed a good condition minimizing shade and reflection. When soil water content increased, illumination intensity should be greater to compensate decrease in brightness. Results of the paper would be useful for construction, test, and application of the sensor.

• Journal of Periodontal and Implant Science
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• 제30권3호
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• pp.609-619
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• 2000

Cyclosporin A(CsA) is now widely used to treat organ transplant recipients. But CsA has various short-and long-term side effects. Especially, gingival hyperplasia is not easy to resolve since its nature is still unknown. This study discusses the pathogenesis of CsA-induced gingival hyperplasia on the basis of data obtained from light and electron microscopic studies of biopsis from patients on CsA treatment after kidney transplantation. Light microscopically, the multilayered squamous epithelium showed an irregular surface of parakeratosis and deep invaginations in the subepithelial tissue. At lamina propria, we observed bundles of irregularly arranged collagen fiber, some fibroblasts, numerous capillary vessels and a large diffuse infiltration of plasma cells. Ultrastructurally, many fibroblasts, collagen fibers, collagen fibrils were present in lamina propria. On the basis of the data collected, we propose that the morphological features of the dimensional increase in gingival tissue associated with CsA treatment in kidney transplant patients may be considered proliferative fibroblasts, collagen fibers, collagen fibrils in lamina propria.

• 한국세라믹학회지
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• 제43권1호
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• pp.22-27
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• 2006

The electronic band structures of Metal-doped titanium dioxide, M-doped $TiO_2$ (M=Co, Cr, Fe), have been studied by using XRD, UV-vis diffuse reflectance spectrometer and FP-LAPW (Full-Potential Linearized Augmented-Plane-Wave) method. The UV-vis of M-doped $TiO_2$ (M=Co, Cr, Fe) showed two absorption edges; the main edge due to the titanium dioxide at 387 nm and a shoulder due to the doped metals at around 560 nm. The band gap energies of Co, Cr and Fe-doped $TiO_2$ calculated by FP-LAPW method were 2.6, 2.0, and 2.5 eV, respectively. The theoretically calculated band gap energy of $TiO_2$ by using FP-LAPW method was the same as experimental results. FP-LAPW method will be useful for fabrication and development of photo catalysts working under visible light.

• 대한전자공학회논문지SP
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• 제41권1호
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• pp.37-46
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• 2004

본 논문에서는 관찰자의 시야에 들어오는 3차원 영상을 정확하게 재현하기 위한 분광분포 기반의 영상재현알고리즘을 제안한다. 빛의 투과 및 굴절을 모델링하기 위해 컴퓨터 그래픽에서 많이 사용되고 있는 광선추적기법을 이용하고, 정확한 실사영상(realistic image)을 재현하기 위하여 물체의 물리적 특성을 반영하는 분광분포를 고려하였다. 광원에서 출발한 빛을 추적하여 더욱 정확한 실사영상을 재현하기 위해 음영모델을 두 가지의 측면에서 개선하여 적용하였다. 첫째는, 빛이 투과할 때에 발생하는 에너지의 감소를 Bouguer-Beer의 법칙을 적용하여 고려하였다 둘째는, 일반적인 상수로 정의하던 주변광의 요소를 주위 물체들의 반사광을 고려한 새로운 주변광으로 개선하여 적용하였다. 제안한 기법을 이용한 시뮬레이션을 통하여 실사영상에 근접한 3차원 영상을 재현할 수 있었다.

• 한국멀티미디어학회논문지
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• 제1권1호
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• pp.26-36
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• 1998

2차원 밝기 영상에서 3차원 정보를 얻는 문제는 컴퓨터 시각 연구에서 매우 중요한 분야를 차지하고 있다. 이러한 목적을 위해 먼저 2차원 영상을 취득할 때 카메라의 위치, 광원의 방향, 영상내 물체의 반사특성 등 본질적인 정보를 이용한다. 이중에서 물체의 표면 반사특성은 매우 중요한 단서가 된다. 과거에는 물체의 반사특성을 Lambertian 반사만을 전제하여 연구를 진행했지만 실세계의 물체는 대부분 Non-Lambertian 반사특성을 갖는다. 본 논문에서는 2차원 밝기 영상에서 물체의 반사특성을 해석하고, 반사특성 파라미터를 추정하여 물체의 형상을 복구하는 새로운 방법과 반사특성을 모르는 상황에서 신경회로망 학습에 의해 형상을 복구하는 방법을 제안한다. 물체의 반사특성은 전반사 성분과 난반사 성분을 함께 갖는 Non-Lambertian 면을 그 대상으로 하며, 이러한 반사특성은 전반사(Torrance-Sparrow) 모델과 난반사(Lambertian) 모델의 선형적인 합으로 설명될 수 있다. 본 논문에서 제안한 Photometric Matching은 주변 화소의 밝기 분포를 고려하여 참조영상과의 매칭을 통한 형상복구 알고리듬으로써 기존의 Photometric Stereo에 근본을 두고 있지만, 잡음 및 오차의 누적 정도가 향상되었다. 또한 물체의 반사특성을 모르는 상황에서 신경회로망 학습에 의한 형상복구방법을 제안한다. 이 방법은 역전파 학습알고리듬을 이용해 광원 방향에 따른 밝기값에 대해 면법선을 교사하여 형상을 결정한다.

• 천문학회보
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• 제36권2호
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• pp.117.1-117.1
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• 2011

We present the smoothness of mid-infrared sky brightness from the Japanese infrared astronomical satellite, AKARI observations. AKARI monitored the north ecliptic pole (NEP) during its cold phase with nine wavebands from 2.4 to 24 ${\mu}m$, out of which six mid-infrared bands are used in this study. Simple sinusoidal fit to the seasonal variation of the sky brightness shows that the mid-infrared brightness towards the NEP is not affected by small-scale features of the interplanetary dust cloud. We applied the power spectrum analysis to the images to search for the fluctuation of sky brightness. The fluctuation powers at 200 arcsecond are estimated to be at most $1.58{\pm}0.33\;nW\;m^{-2}sr^{-1}$ or 0.13% of the total brightness at $7{\mu}m$ and a tleast $0.64{\pm}0.11\;nW\;m^{-2}sr^{-1}$ or 0.02% at $18{\mu}m$. The residual fluctuations at a few arcminute scales at short mid-infrared wavelengths (7, 9, and 11 ${\mu}m$) are consistent with those expected from the diffuse galactic light. At long mid-infrared wavelengths (15, 18, and 24 ${\mu}m$) the measured fluctuations are comparable to or smaller than the one caused by photon noise and their sources are not identified. We conclude that the upper limit of the fluctuation in the zodiacal light is about 0.02% of the sky brightness.