• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.78-81
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• 1999

Light penetration depth in high-density Chlorella cultures can be successfully estimated by Beer-Lambert's law. The efficiency of light energy absorption algal cultures was so high that algal cells near the illuminating surface shade the cells deep in the culture. To exploit the potential of high-density algal cultures, this mutual shading should be eliminated or minimized. However, providing more light energy will not ease the situation and it will simply drop the overall light utilization efficiency.

• Medical Lasers
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• 제10권3호
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• pp.146-152
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• 2021

Background and Objectives Although lasers have been widely applied in tissue treatment, the light penetration depth in tissues is limited by the tissue turbidity and affected by its absorption and scattering characteristics. This study investigated the effect of using an optical clearing agent (OCA) on tissue to improve the therapeutic effect of 1064 nm wavelength laser light by reducing the heat generated on the skin surface and increasing the penetration depth. Materials and Methods A diode laser (λ = 1064 nm) was applied to a porcine specimen with and without OCA to investigate the penetration depth of the laser light and temperature distribution. A numerical simulation using the finite element method was performed to investigate the temperature distribution of the specimen compared to ex-vivo experiments using a thermocouple and double-integrating sphere to measure the temperature profile and optical properties of the tissue, respectively. Results Simulation results showed a decrease in tissue surface temperature with increased penetration depth when the OCA was applied. Furthermore, both absorption and scattering coefficients decreased with the application of OCA. In ex-vivo experiments, temperatures decreased for the tissue surface and the fat layer with the OCA, but not for the muscle layer. Conclusion The use of an OCA may be helpful for reducing surface heat generation and enhance the light penetration depth in various near-infrared laser treatments.

• 한국레이저가공학회지
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• 제5권1호
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• pp.33-42
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• 2002

In order to investigate the characteristics of the plasma induced by lap-joint CO$_2$ laser welding of automotive steel sheets, the effects of welding speed, shield gas flow rate, gap size, and laser beam defocus to plasma intensity emitted from keyhole have been investigated. The plasma light is measured by fiber and photodiode. Also, the plasma images were captured by the high speed digital camera in 1000frames/sec in order to correlate the plasma light signal with plasma pattern. From the results, it is observed that the difference of the plasma intensity for between the deep penetration and partial penetration exists from 1.2 to 2 times. The plasma light intensity decreased in case of the deep penetration Is observed due to the exhausting of the plasma gas under the sheet. On the other hand, under the conditions of the deep penetration, the plasma intensity is significantly increased by controling the conditions decreasing the penetration depth. It was specially founded that the effect of 0.3mm gap size at partial penetration condition is approximately similar to deep penetration in 0mm gap. It is concluded that the plasma intensity is able to evaluate the penetration depth in lap-joint welding and appears to offer the most straightforward correlation to the welding process.

• 대한의용생체공학회:의공학회지
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• 제20권2호
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• pp.199-204
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• 1999

생체조직내의 정확한 광선량 측정이 PDT 치료의 효과에 중요한 영향을 주므로 본 연구에서는 광선량 측정을 위해서 Monte Carlo 시뮬레이션을 이용하였다. 실험에 사용한 계수는 실제 생체조직의 광학계수이고 위상함수는 Henyey-Greenstein 위상함수를 사용하였다. 결과는 깊이에 따른 Fluency rate의 변화로 나타내었으며 기존 이론과의 차이는 0.35%에 지나지 않았다. 실험에 사용한 생체조직은 인체조직, 돼지조직, 쥐간조직, 토기근육조직이다. 대부분의 생체조직은 가시광선영역에서 큰 산란계수를 가지고 있으며 이것은 투과도에 큰 영향을 미치는 것으로 밝혀졌다. 가시광선 영역에서 인체조직의 투과 깊이는 1.5~2cm이었다. Monte Carlo 시뮬레이션을 이용하여 생체조직내의 광전파(light propagation), 광선량(light dosimetry), 에너지율(fluence rate), 투과깊이(penetration depth)를 효과적으로 측정할 수 있음을 보여주었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권5호
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• pp.352-358
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• 2001

Because algal cells are so efficient at absorbing incoming light energy, providing more light energy to photobioreactors would simply decrease energy conversion efficiency. Furthermore, the algal biomass productivity in photobioreactor is always proportional to the total photosynthetic rate. In order to optimize the productivity of algal photobioreactors (PBRs), the oxygen production rate should be estimated. Based on a simple model of light penetration depth and algal photosynthesis, the oxygen production rate in high-density microalgal cultures could be calculated. The estimated values and profiles of oxygen production rate by this model were found to be in accordance with the experimental data. Optimal parameters for PBR operations were also calculated using the model.

• The Journal of Korean Physical Therapy
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• 제23권6호
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• pp.77-84
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• 2011

Purpose: The objectives of this study were to determine the enhancing effect of iontophoresis method as it transdermally deliver methylene blue (MB) using visual examination, in terms of penetration depth and tissue distribution in the skin, and to determine the effect of application duration on the efficacy of iontophoresis. Methods: Twenty-four male Sprague-Dawley rats were randomly divided into 5-, 10-, 20-, and 40-minute groups. These rats were exposed to either topical or anodic iontophoresis of 1% MB using a direct current of $0.5mA/cm^2$ for 5, 10, 20, and 40 minutes. Using cryosections of rat tissues, the penetration depth of MB was measured using light microscopy. Results: Significant differences in the penetration depth (F=54.20, p<0.001) were detected among the four groups. Post hoc comparisons of the penetration depth of MB data pooled across groups showed no significant difference between all topical application groups and 5-minute iontophoresis group, but did reveal a significant difference in the penetration depth between all topical application groups and 5-minute iontophoresis group versus 10-minute group, between the 10-minute and 20-minute group, and between the 20-minute and 40-minute iontophoresis group (p<0.05). Conclusion: The results demonstrate that iontophoresis enhances transdermal delivery of MB across stratum corneum of skin barrier by visual examination. Furthermore, the penetration depth of iontophoretic transdermal delivery of MB was dependent on the application duration. The duration of iontophoresis is one of the important factor in the efficacy of iontophoresis application.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.48-54
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• 2002

Since photocatalysts are activated by lights of UV wavelengths, plasma is alternatively used as a light source for a photocatalytic reactor. Light intensity generated by plasma is proportional to the surface area of catalytic material, and this, in many practical applications, is prescribed by the geometry of a plasma generator. Thus, it is crucial to increase the surface area far sufficient light intensity for photocatalytic reaction. For example, in a pack-bed type reactor, multitudes of beads are used as a substrate in order to increase the surface area. Honeycomb monolith type substrate, which has very good surface area to volume ratio, has been difficult to apply plasma as a light source due to the fact that light penetration depth through the honeycomb monolith was too short to cover sufficient area, thus resulting in poor intensity for photocatalytic reaction. In this study, nonthermal plasma generation through a photocatalytic reactor of honeycomb monolith substrate is investigated to lengthen this short penetration depth. The ceramic honeycomb monolith substrate used in this study has the same length as a three way catalyst used fur automotive applications, and it is shown that sufficient light intensity for photocatalytic reaction can also be obtained with honeycomb monolith type reactor.

• 한국수산과학회지
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• 제10권4호
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• pp.237-241
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• 1977

1976년 9월 20일 부터 24일 사이에 북서태평양(Kamchatka 근해에서 투명도, 태양광선의 적색광(과장 : 600\~620\;nm)에 대한 표면조도 및 수심별 수중조도와 태양고도, 기온 및 표층수온 등을 조사한 결과를 요약하면 다음과 같다. 1. 본 조사해역의 평균투명도는 $10.6m(9\~l2m)\$로 나타났다. 2. 태양광선의 적색광에 대한 해수의 흡수계수는 $0.178\~0.376$(평균 0.278)였다. 3. 적색광에 대한 해수의 흡수계수 m와 투명도 D와의 관계는 m=3.347/D로 나타났다. 4. 관측된 평균기온은 $9.49^{\circ}C(7.8-12.6^{\circ}C)$ 였고, 평균표층수온은 $6.58^{\circ}(5.8-7.6^{\circ}C$)로 나타났다. 5. m층에서 적색광에 대한 수중투과율은 수심 5 m층에서 표면창의 $6.45\~23.5\%$(평균 $16.36\%$), 수심 10 m층에서는 $1.38\~7.31포$(평균 $3.65\%$)였고, 수심 20 m층에서는 $0.048\~0.647\% $(평균 0.276\%)로 나타났다.

• 한국수산과학회지
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• 제10권3호
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• pp.173-177
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• 1977

1976년 9월부터 10월 사이에 동해 북동해역 9개 관측점에서 투명도, 태양광선의 적색광(파장;$600\~620nm$)에 대한 수심별 수중조도와 태양고도 등을 조사하여 검토한 결과를 요약하면 다음과 같다. 1. 본 조사해역의 평균투명도는 $19.8m(15\~23m)$로 나타났다. 2. 태양광선의 적색광에 대한 해수의 흡수계수는 $0.142\~0.323$(평균 0.232)였다. 3. 적색광에 대한 해수의 흡수계수 m와 투명도 D와의 관계는 m=4.93/D로 나타났다. 4. 적색강의 수중투과율은 수성 5m층에서 표면광의 $15\~34.2\%$(평균 $23.11\%$), 수신 10m층에서는 $3.04\~12\%$(평균 $6.49\%$)였고, 수심 20m층에서는 $0.113\~1.27\%$(평균 $0.698\%$)로 나타났다.

• 한국전기전자재료학회논문지
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• 제29권4호
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• pp.247-249
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• 2016

In this study, we investigated the color change of the normal light gray granite as the high value color granite. By coating the metal catalyst liquid on the surface of granite stone, the metal particles were penetrated into the granite and the color of granite was changed permanently through the annealing treatment. To increase penetration depth into the granite, we used DC (direct current) bias. Two kinds of bias were used such as DC bias and pulse DC bias. And the penetration time was changed as 30 and 60 min. In all cases, the color granite were successfully obtained. Regardless of the catalyst reaction time, the penetration depth was increased by using the bias treatment. We obtained a penetration depth of 21 mm with the DC pulse bias during 60 min.