섬유주절제술 후 안압하강이 빛간섭단층혈관촬영을 이용한 혈관밀도 변화에 미치는 영향

강민승(Min Seung Kang),권정민(Jeong Min Kwon),신종훈(Jonghoon Shin) 대한안과학회 2021 대한안과학회지 Vol.62 No.2

목적: 섬유주절제술 후 빛간섭단층혈관촬영을 이용한 시신경유두주위 및 황반부 혈관밀도 변화를 평가하고자 한다. 대상과 방법: 녹내장 환자 중 섬유주절제술을 시행한 20안을 대상으로 후향적 연구를 실시하였다. 수술 전후의 안압, 빛간섭단층촬영 및 빛간섭단층혈관촬영으로 측정한 시신경유두주위 망막신경섬유층두께, 황반부 신경절-내망상층두께, 시신경유두주위 및 황반부 혈관밀도를 Wilcoxon 검정으로 분석하였으며, 혈관밀도 변화에 영향을 주는 인자를 회귀분석으로 확인하였다. 결과: 평균 안압은 술 전 31.0 ± 11.80 mmHg에서, 술 후 1개월 및 6개월에 각각 11.47 ± 4.52 mmHg (p<0.001), 11.52 ± 3.34 mmHg로 유의한 감소를 보였다(p<0.001). 술 전에 비해 술 후 6개월에 시신경유두주위 망막신경섬유층두께(p=0.002)는 유의미한 증가를 보였다. 수술 후 시신경유두주위 혈관밀도는 유의미하게 증가하였으며(p=0.007), 시신경유두주위 혈관밀도의 변화량은 안압감소량이 클수록(p<0.001), 술 전 시신경유두주위 혈관밀도가 낮을수록(p=0.003) 증가하였다. 시신경유두주위 망막신경섬유층두께는 수술 전후 안압하강이 클수록 더 많이 증가하는 양상을 보였다(p=0.011). 결론: 빛간섭단층혈관촬영을 이용한 시신경유두주위 혈관밀도 측정이 섬유주절제술 시행 후 안압하강에 의한 시신경 손상의 가역적 변화를 확인하는 데 유용할 것으로 사료된다. Purpose: To evaluate peripapillary and macular vessel density changes in glaucoma patients after lowering intraocular pressure (IOP) by trabeculectomy, using optical coherence tomography (OCT) angiography. Methods: A retrospective study was conducted on 20 glaucomatous eyes that underwent trabeculectomy. Preoperative and postoperative IOP, peripapillary retinal nerve fiber layer (RNFL) thickness, macular ganglion cell-inner plexiform layer thickness, peripapillary and macular vessel density measured by OCT, and OCT angiography were analyzed by the Wilcoxon signed-rank test. A regression analysis was performed to identify the factors influencing the change in vessel density. Results: The mean IOP was 31.0 ± 11.80 mmHg prior to surgery, 11.47 ± 4.52 mmHg at 1 month (p < 0.001), and 11.52 ± 3.34 mmHg at 6 months (p < 0.001). Peripapillary RNFL thickness (p = 0.002) increased significantly 6 months postoperatively. Peripapillary vessel density increased significantly 6 months after surgery (p = 0.007) and the magnitude of the reversal of peripapillary vessel density was significantly associated with a greater reduction in IOP (p < 0.001), and the lower preoperative peripapillary vessel density value (p = 0.003) and change in peripapillary vessel density increased significantly. The improvement in peripapillary RNFL thickness was associated with a greater reduction in the IOP (p = 0.011). Conclusions: Measuring peripapillary vessel density using OCT angiography was useful to identify the reversible changes in optic nerve damage caused by reducing IOP after trabeculectomy.

Large Low-energy Oscillator Strength for Eu 4f Electrons of a Rare-earth Zintl Compound: EuIn_2P_2

Nirpendra Singh,이주열 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.3

A newly found Zintl compound EuIn_2P_2 has been investigated within the density-functional theory, and results of a detailed investigation of its electronic structure and related properties are reported. We employed the so-called LSDA+U method (LSDA: local-spin-density approximation) with varying U from 0 eV to 7 eV to take into account the strong on-site Coulomb repulsion between the Eu 4f -electrons and to reproduce the semiconducting energy gap of 3.2 meV experimentally observed by J. Jiang and S. M. Kauzlarich [Chem. Mater. 18, 435 (2006)]. The calculations, however, could not reproduce the energy gap even for the largest U value of 7.0 eV because the experimental gap was not an optical gap, but it was deduced from the temperature dependence of resistivity at 26 − 60 K; thus, the experimental gap was not a real ‘semiconducting’ gap. The calculated optical-conductivity spectrum with U = 7.0 eV could not reproduce the experimental spectrum, while with simple LSDA, the calculated spectrum resembled the experimental one rather successfully. Therefore, it seems that the LSDA+U method is not suitable to correctly simulate the optical properties of this compound. Contrary to the expectation, we found that EuIn_2P_2 had a large oscillator strengths for f ! d transitions in the low-energy range (below 1.5 eV); i.e., the peaks located at ∼0.6 eV and ∼1.1 eV in the experimental spectrum are mainly due to transitions from f -bands to d-bands, in which joint density-of-states effects play a key role. We also found that the magneto-optical Kerr effect was quite large in the EuIn_2P_2 compound.

An Optical-Density-Based Feedback Feeding Method for Ammonium Concentration Control in Spirulina platensis Cultivation

( Yi Lu Bao ),( Shu Mei Wen ),( Wei Cong ),( Xia Wu ),( Xiang Ning Zheng ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.7

Cultivation of Spirulina platensis using ammonium salts or wastewater containing ammonium as alternative nitrogen sources is considered as a commercial way to reduce the production cost. In this research, by analyzing the relationship between biomass production and ammonium- N consumption in the fed-batch culture of Spirulina platensis using ammonium bicarbonate as a nitrogen nutrient source, an online adaptive control strategy based on optical density (OD) measurements for controlling ammonium feeding was presented. The ammonium concentration was successfully controlled between the cell growth inhibitory and limiting concentrations using this OD-based feedback feeding method. As a result, the maximum biomass concentration (2.98 g/l), productivity (0.237 g/l·d), nitrogen-to-cell conversion factor (7.32 gX/gN), and contents of protein (64.1%) and chlorophyll (13.4mg/g) obtained by using the OD-based feedback feeding method were higher than those using the constant and variable feeding methods. The OD-based feedback feeding method could be recognized as an applicable way to control ammonium feeding and a benefit for Spirulina platensis cultivations.

Electronic Structures and Optical Properties of Spinel ZnCr2O4

Nirpendra Singh,이주열 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.5

The electronic structures and optical properties of zinc chromite, ZnCr2O4, were calculated using the density-functional theory within the local-spin-density approximation (LSDA), the LSDA plus Hubbard-like parameter U, LSDA+U, and the spin-polarized generalized-gradient approximation. ZnCr2O4 was found to be a direct-band-gap semiconductor with an optical band gap of 2.9 eV, with the uppermost valence bands (lowermost conduction bands) having mainly Cr-t2g (Cr-e<SUB>g</SUB>) characteristics. The calculated band gap using LSDA+U showed better agreement with the available experimental data than previous calculations. The optical-conductivity and the reflectivity spectra were also calculated. The calculated reflectivity spectrum exhibited two peaks, one at ~3.5 eV and the other at ~5.8 eV, which were assigned to the electronic interband transitions from the O-2p to the Cr-3d states and from the O-2p derived bands to the Cr eg bands, respectively.

Development of an Optical Tissue Clearing Laser Probe System

여창민,강희성,배윤진,박지훈,이경중,J. Stuart Nelson,정병조 한국광학회 2013 Current Optics and Photonics Vol.17 No.4

Although low-level laser therapy (LLLT) has been a valuable therapeutic technology in the clinic, its efficacy may be reduced in deep tissue layers due to strong light scattering which limits the photon density. In order to enhance the photon density in deep tissue layers, this study developed an optical tissue clearing (OTC) laser probe (OTCLP) system which can utilize four different OTC methods: 1) tissue temperature control from 40 to 10℃; 2) laser pulse frequency from 5 to 30 Hz; 3) glycerol injection at a local region;and 4) a combination of the aforementioned three methods. The efficacy of the OTC methods was evaluated and compared by investigating laser beam profiles in ex-vivo porcine skin samples. Results demonstrated that total (peak) intensity at full width at half maximum of laser beam profile when compared to control data was increased: 1) 1.21(1.39)-fold at 10℃; 2) 1.22 (1.49)-fold at a laser pulse frequency of 5 Hz; 3)1.64 (2.41)-fold with 95% glycerol injection; 4) 1.86 (3.4)-fold with the combination method. In conclusion,the OTCLP system successfully improved the laser photon density in deep tissue layers and may be utilized as a useful tool in LLLT by increasing laser photon density

Evaluation of the Photo-generated Carrier Density of GaAs Solar Cells by Using Electrical and Optical Biased Electroreflectance Spectroscopy

소모근,조현준,한임식,김종수,이상준,노삼규,임재영 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.4

In this work, to investigate the optical and the electrical properties of GaAs solar cells, we adopted optical/ electrical biased electroreflectance spectroscopy (ER) and current-voltage (J-V) measurements. The p-n junction’s electric fields were evaluated through an analysis of the Franz- Keldysh oscillations (FKOs) in the ER spectra. By comparing the electrical and the optical biased ER and optical biased J-V results, we calculated the carrier densities contributing to the photovoltage (pv) and the photocurrent (J ). We confirmed that the pv could affect the field screening for the p-n junction’s electric field. With increasing number of incident photons (ph), the ratio of pv to J was almost constant. From these results, for a concentrated photovoltaic device, we propose that the photovoltaic effect can affect the solar cell’s efficiency in the relatively high excitation intensity region.

Synthesis, Structural, Time-Dependent Density-Functional Theory, Thermal Annealing and Optical Properties for Doped Polymer Nanostructured Thin Films as Optoelectronic Devices

Ahmed F. Al-Hossainy,Mohamed Sh. Zoromba 한국고분자학회 2021 폴리머 Vol.45 No.4

The dependence of structural and optical characteristics on the thermal annealing of a doped poly(4-phenylenediamine-co-2-aminophenol) nanostructured thin film [P4D2AP]<SUP>TF</SUP> as a doped polymer conductor nanostructured thin film was studied. [P4D2AP]<SUP>TF</SUP> was fabricated as a thin film (100 ± 2 ㎚) using the spin coating method. Various characterization methods for [P4A2AP]<SUP>TF</SUP> like Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopic (UV-Vis), thermogravimetric analysis (TGA), and optical characteristics have been studied. The resulted X-ray diffraction (XRD) and scanning electron microscope (SEM) data have been employed to study interface composites. Density functional theory (DFT) was used for optimization by atomic orbital DFT code (DMol³) and Cambridge serial total energy package (CASTEP). Spectroscopic and structural characteristics for the thin film have confirmed the chemical composition and XRD observations revealed the same crystal structure. The fabricated film was annealed in the air for 1h at 100 and 200 ℃. XRD examination of [P4D2AP]<SUP>TF</SUP> displayed that symmetry is an orthorhombic with a space group (Pmcn). The optical characteristics demonstrated that the thin film has a relatively high absorbance of 95%. The calculated energy gaps are 2.523 eV and 2.504 eV for DFT and experimental, respectively. In addition, the optoelectrical parameters of the film have been calculated for absorption index (k(λ)), refractive index (n(λ)), dielectric constant, and optical conductivity. CASTEP simulated values are consistent with the experimental values for optical parameters of [P4A2AP]<SUP>TF</SUP>. The findings of the structural and optical characteristics described the fabricated thin film can be utilized as a candidate material for optoelectronic devices and solar cells.

빛간섭단층혈관조영술을 이용한 단안 원발급성폐쇄각발작 후 망막모세혈관분포 분석

이재협(Jae Hyup Lee),김정림(Jung Lim Kim) 대한안과학회 2021 대한안과학회지 Vol.62 No.3

목적: 원발급성폐쇄각발작 후 시신경의 녹내장성 변화를 보이지 않는 환자에서 빛간섭단층혈관조영술을 이용하여 시신경 및 망막모세혈관분포를 확인하고자 하였다. 대상과 방법: 단안 원발급성폐쇄각발작 이후 성공적인 치료를 받았으며, 시신경의 녹내장성 변화를 보이지 않은 환자(20명)를 대상으로 병변안(20안)과 원발급성폐쇄각발작이 오지 않은 반대안(20안)을 대조군으로 하여 후향적으로 비교하였다. 급성폐쇄각발작 후 평균 8주에 빛간섭단층촬영을 통해 망막신경섬유층의 두께와 신경절세포-내망상층의 두께를 측정하였고, 빛간섭단층혈관조영술을 통해 시신경유두주위와 황반부의 혈관밀도 및 관류밀도, 오목무혈관부위의 면적 및 둘레를 측정하여 비교 분석하였다. 결과: 시신경유두주위 망막신경섬유층과 황반부 신경절세포-내망상층의 두께는 두 군에서 유의한 차이를 보이지 않았다. 시신경유두주위 혈관밀도, 관류밀도 또한 차이가 없었으나, 황반부 중심영역의 혈관밀도와 관류밀도의 경우 병변안에서 유의한 감소를 보였다 (p=0.003, p=0.046). 그 외 황반부 영역의 혈관밀도, 관류밀도와 오목무혈관부위의 면적 및 둘레는 양안에서 유의한 차이가 없었다. 결론: 급성폐쇄각발작 후 적절한 치료를 시행하여 시신경과 신경절세포-내망상층에서 녹내장성 변화가 관찰되지 않았으나 황반부 혈관밀도와 관류밀도는 감소하였다. 이런 경우 향후 구조적인 변화가 발생하는지에 관한 주의 깊은 관찰이 필요할 것이라 생각된다. Purpose: We evaluated changes in the retinal capillary networks of patient’s acute primary angle closure (APAC) who were successfully treated and who lacked glaucomatous alterations. Methods: Twenty patients for whom unilateral episodes of APAC were successfully treated were included in this retrospective cross-sectional study. At an average of 8 weeks after APAC, the thicknesses of the circumpapillary retinal nerve fiber layer (RNFL) and the ganglion cell-inner plexiform layer (GCIPL) were measured via spectral domain optical coherence tomography. Circumpapillary and macular vessel densities, perfusion density (PD), and the area and perimeter of the foveal avascular zone (FAZ) were measured with the aid of OCT angiography (OCTA). We compared the values between APAC eyes and the fellow eyes. Results: We found no significant differences between groups in the thickness of any RNFL or GCIPL sector, or in the circumpapillary vessel or perfusion density. However, within a radius of 0.5 mm from the fovea (the center), the vessel and perfusion densities were significantly lower in affected than in fellow eyes (p = 0.003, p = 0.046 respectively). The vascular factors of other macular sectors, and the FAZ area and perimeter did not differ between the groups. Conclusions: Early reductions in macular vessel and perfusion densities were evident after effective APAC treatment. Therefore, follow-up must evaluate whether the blood flow reduction causes structural damage.

가축분뇨수의 색소오염물질 분해과정 측정 영상처리 시스템

이대원,김현태,김용석,민병로,이강춘,박은석,한정환,이수희,김정동 한국축산환경학회 2001 축산시설환경학회지 Vol.7 No.2

This study conducted to monitor decomposition process of the charomatophore pollution solution of an animal slurry by using a CCD camera. After the solution was put into test tube, the images(R, G, B, H, L, S) values of the solution were measured by the imgae processing system, and those of it\`s optical density were measured for three hours to be decomposed by microscopic organism. The values of measured for three hours to be decomposed by microscopic organism. The values of measured images(R, G, B, H, L, S) were analysed and compared with those of the optical density. Some of the results are as follows. 1. High correlation coefficients, which analyzed by using data on linear equations, were 0.9557 and 0.9672. They were decreased regularly in this R-value experiment of RGB level. The microscopic organism in this experiment was effective for decomposition of the red charomatophore pollution solution. 2. The values of all correlation coefficients from relationship between RGB-value and optical density were more than 0.95 except H-values. RGB-values, which were average values of summed R, G, B values, had correlation coefficients of 0.9863, 0.9937. These results showed so good relationship that decomposition process of charomatophore pollution solution could be monitored by a image processing system.

성긴 광흐름 속에서 접촉시간 지각

김남균 한국인지및생물심리학회 2010 한국심리학회지 인지 및 생물 Vol.22 No.2

The present study examined human observers’ perceptual capacity to estimate time-to-contact (TTC) of an approaching object under severely perturbed or impoverished optic flow that compromised TTC information, in particular, local tau1. In Experiment 1, non-spherical objects approached the observation point while rotating either about one (horizontal or vertical) or two axes. The objects were depicted using random dots that varied in density (4, 16, 64, or 256 dots), half of which were projected to the observer. Under object rotation, the surface dots were displaced or even disappeared. These manipulations severely compromised the optical pattern specifying local tau1. In Experiment 1, performance degraded with decreasing dot density. Particularly, performance in the 4 dot density condition differed significantly from performance in the three higher density conditions. Experiment 2 examined whether these results accurately depicted the capacity of the human visual system. Objects either approached, or retreated from, the observation point; and participants were asked to judge the direction of the object’s motion. With an overall accuracy of 89%, most objects’ motion directions were identified reliably, even in the 4 dot density condition. Taken together, the present study demonstrated that the human visual system is capable of coping with adverse conditions by extracting requisite information, in particular, local tau1, that specifies the TTC of an approaching object, even from severely perturbed and impoverished optic flow. However, the present results also demonstrate that, under certain extreme conditions such as those engendered by rugby ball shaped object that rotated 90 deg over their approaches to the observation point, the visual system can fail, a finding consistent with that reported by Gray and Regan (2000). 물체가 관찰자를 향하여 다가올 때, 그 물체가 이루는 각, 즉 물체각의 상대적 팽창률의 역수는 그 물체의 도착시간과 일치한다. 관찰자는 tau라고 명명된 이 광학정보를 이용하여 움직이는 물체를 잡거나 다가오는 물체를 피하는 행동을 시간적으로 통제할 수 있다. 하지만 회전하며 날아오는 럭비공 같은 비대칭 비등방형 물체는 광흐름을 교란시키며, 그 결과 tau의 추출을 어렵게 한다. Gray와 Regan(2000)은 이러한 가능성을 검증하였으며, 그 결과 인간시각체계가 tau라는 단안정보에 입각하여 회전하며 접근하는 비원형 물체의 접촉시간을 탐지할 능력이 결여되었다고 주장하였다. 그에 반해, 다양한 결무늬를 입힌 비원형 물체를 이용하여 접촉시간 지각능력을 검증한 김남균(2009)은 기존의 접촉시간 연구에서 보고한 결과들과 비슷하거나 더 우수한 결과를 발견하였다. 하지만 김남균의 연구는 물체 내부 결 조직이 묘사되었다는 점을 제외하고는 참가자들이 어떤 정보에 근거하여 접촉시간을 탐지할 수 있었는지를 규명하기가 어려운 문제점을 내재하고 있다. 이 연구에서는 이러한 문제점을 보완하여, 물체를 검은색의 무선점들로 묘사하였으며, 무선점들의 숫자도 조작하여, tau가 광흐름 속에서 명시되는 정도를 변화시켰다. 이런 물체들을 이용하여 접촉시간 탐지능력을 실험 1에서 검증한 결과, 접근시간 예측이 기존의 문헌에서 보고된 수행능력과 크게 차이가 나지 않는다는 사실을 발견하였다. 하지만 4점 결밀도에서의 수행능력은 다른 3개의 고밀도 조건에서의 수행능력과는 차이가 있었다. 낮은 수행능력이 지각능력을 반영하는지를 평가하기 위해서 실험 2를 실시하여, 실험 1의 결과가 정확한 광패턴, 즉 팽창여부의 탐지에 근거하였는지를 검증하였다. 그 결과 정확한 광패턴 지각능력이 발견되었다. 특히 4점 결밀도 조건에서도 80%이상의 정확도를 보였다. 하지만 럭비공 물체에서 광패턴을 추출하는 것이 다른 물체에 비해 더 어려웠다는 사실을 발견하였으며, 이런 결과는 동일한 물체를 사용한 Gray와 Regan의 연구가 연구에 사용한 물체의 특수성에 근거하여 발생했을 가능성을 제기한다.