• 한국안전학회지
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• 제31권5호
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• pp.1-6
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• 2016

The performance of a set of low-cost optical components used for measuring the optical density of PM particles was evaluated in the present study. To this end, the set of low-cost optical components was replaced with that of general optical components used to measure the PM optical density under identical experimental conditions. The optical densities measured from the set of general optical components were then compared to those obtained from the set of low-cost optical components. While the optical density is measured, another key parameter, the dimensionless extinction constant of PM particles (which is needed to optically measure the PM concentration) was also determined in the present study. The experimental results indicate that the optical density and PM concentration measurements performed by low-cost optical components are feasible, producing trackable variations in the OD and concentrations compared to values obtained from the set of general optical components.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2002년도 춘계 국제 학술대회
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• pp.44-46
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• 2002

This study was conducted to identify the proper analytical conditions regarding optical density for endotoxin analysis in the workplace using metalworking fludis. Our study found the "onset method" was more accurate than "time to Vmax" Reproducibility and accuracy analyzed by "onset method" was more greater than those by "time to Vmax""0.03"of optical density was the most appropriate analytical condition among onset method. Through this analytical condition, 0.998 of linearity was obtained and recovery rate ranged from 88％ to 105％ at endotoxin concentration below 5 EU/$m\ell$. No significant difference of endotoxins between "0.03"and "0.05" of optical density was observed from this study. Furthermore, correlation coefficients between them were statistically significant(p＜0.01). This study concluded that 0.03”or "0.05" of optical density is used to analyze endotoxin. Of these optical density value, value with higher linearity should be used to analyze endotoxin in environmental samples.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.537-540
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• 2003

In this paper, we evaluated error correction performance and recording density of an optical disc system. The performance of Low-Density Parity Check code (LDPC) is compared to the HD-DVD (BD) ECC. The recording density of optical disc can be increased by reducing the redundancy of the user data. Moreover, since the correction capability of LDPC with decreased redundancy is better than that of BD, the recording density can also be increased by reducing the mark length of the data on the disc surface.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.124-128
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• 2014

We derive joint probability density functions (JPDFs) for two adjacent data from direct-detection optical receivers in dense wavelength-division multiplexing systems. We show that the decision using two data per bit can increase the receiver sensitivity compared with the conventional decision. Our JPDFs can be used for software-defined optical receivers enhancing the receiver sensitivities for intensity-modulated channels.

• KSBB Journal
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• 제9권5호
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• pp.457-463
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• 1994

곰팡이 세포농도를 측정하기 위하여 pellet에 대한 침강 특성을 고려하여 홉광도를 측정하는 새로운 방법을 개발하였다$.$ Pellet의 침강을 막기 위해 spec trophotometer의 cuvette 내에셔 소형 마그네닥바 로 시료를 적절히 교반시켰는데 그 결과 안정된 값의 흡광도를 얻을 수 있었으며 세포의 건조중량과 흡광도간에 선형적인 관계가 었는 것으로 나타났다. 그러나 크기별로 pellet입자를 분리한 결과 입자 크 기별로 통일한 흡광도에서 셔로 다른 건조중량을 갖는 것으로 나타났으며 입자의 직경이 $355{\mu}m$ 이상인 경우 교반에 의한 홉광도를 측정할 수 없었다. 이상의 결과로부터 pellet을 형성하는 곰팡이 배양액의 경우 pellet의 침강 특성을 고려해 줌으로써 흡광도 를 이용한 곰팡이 세포농도의 측정이 가능하다는 결론을 얻었다.

• 대한소아치과학회지
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• 제26권1호
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• pp.109-118
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• 1999

The aim of this study was to evaluate the optical density of laser fluorescence for detection of incipient caries. Prepared and polished bovine enamel specimens were demineralized in a STPP solution for varying periods of time between 3 hrs. and 60 hrs. with an area of sound enamel retained on each specimen. The randomized specimens were analyzed for optical density of enamel demineralization using laser fluorescence. The specimens were sectioned and examined lesion depth by polarizing light microscope. Results were analyzed statistically with SAS program. The results from this study can be summarized as follows: 1. Optical density measured by laser fluorescence and lesion depth measured by polarizing light microscope was increased as demineralization time was increased(p<0.001). 2. Between optical density measured by laser fluorescence and lesion depth measured by polarizing light microscope was correlated highly(${\gamma}{\geq}0.74956$, p<0.001). 3. Regressive equation was obtained in this study as follows. Y=[X-0.260851]/0.000271(R-square:0.5618, p<0.001) (X:DENSITY, Y:DEPTH) In summary, optical density measured by laser fluorescence would be within the range of possibility to quantitatively presume demineralization amount of incipient caries lesion

• 한국초전도ㆍ저온공학회논문지
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• 제21권3호
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• pp.6-12
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• 2019

Extended Drude model has been used to obtain information of correlations from measured optical spectra of strongly correlated electron systems. The optical self-energy can be defined by the extended Drude model formalism. One can extract the optical self-energy and the electron-boson spectral density function from measured reflectance spectra using a well-developed usual process, which is consistent with several steps including the extended Drude model and generalized Allen's formulas. Here we used a reverse process of the usual process to investigate the extended Drude analysis when an additional low-energy interband transition is included. We considered two typical electron-boson spectral density model functions for two different (normal and d-wave superconducting) material states. Our results show that the low-energy interband transition might give significant effects on the electron-boson spectral density function obtained using the usual process. However, we expect that the low-energy interband transition can be removed from measured spectra in a proper way if the transition is well-defined or well-known.

• 한국광학회지
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• 제11권4호
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• pp.261-264
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• 2000

은염 감광성 물질을 이용하여 연속적으로 광밀도가 변화하는 ND filter를 제작하였다. 이러한 filter는 레이저빔의 세기 분포를 변화시켜 원하는 세기 분포를 갖는 레이저빔을 얻을 수 있도록 한다. 광밀도가 filter의 반지름 방향으로 내부에서 외부로 증가하는 형태와 외부에서 내부로 증가하는 두 가지 형태를 만들었다. 원하는 형태의 광밀도를 갖는 filter를 제작하기 위하여 이와 반대의 광밀도를 갖는 마스크를 제작하여야 한다.

• 한국축산시설환경학회지
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• 제7권2호
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• pp.103-110
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• 2001

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.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.168-169
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• 2000

We have tried to enhance the density of the near-field optical memory and to improve the recording/readout speed. The current optical memory has the limitation in both density and speed. This barrier due to the far-field nature can be overcome by the use of the near-field$^{(1)}$ . The optical data storage density can be increased by reducing the size of the nanometric aperture where the near-field is obtained. To fabricate the aperture in precise dimension, we applied the orientation-dependent / anisotropic etching property of crystal Si often employed in the field of MEMS$^{(2)}$ . And so we fabricated the 10$\times$10 aperture array. This array will be also the indispensable part for speeding up. One will see the possibility of the multi-tracking pickup in the phase changing type memory through this array$^{(3)}$ . This aperture array will be expected to write the bit-mark whose size is about 100nm. We will show the recent result obtained. (omitted)