• Medical Lasers
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• v.10 no.3
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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.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.303-311
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• 2020

Scattering-ray generated during plain radiography can cause secondary exposure to organs and tissues other than the target area. Currently, Shielding devices used to reduce radiation exposure are mostly used for radiation protection of workers, and radiation protection of patients is rarely performed. Therefore, this study intends to evaluate the organ dose by scattered-rays and the effectiveness 3D printing materials as a radiation shielding device during plain radiography through simulation. As a result, the absorbed dose for each organ at the time of examination showed a high effect due to the secondary scattering-ray as the distance from the source was close and the organ closer to the skin surface. The dose reduction effect due to the use of 3D printing shielding devices to protect this showed a higher shielding effect in the case of mixed printing materials compared to plastics.

• Journal of Biomedical Engineering Research
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• v.30 no.1
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• pp.18-22
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• 2009

Laser has been widely used in various fields of medicine. Recently, noninvasive low-level laser therapeutic medical devices have been introduced in market. However, low-level laser cannot deliver enough photon density to expect positive therapeutic results in deep tissue layer due to the light scattering property in tissue. In order to overcome the limitation, this study was aimed to develop a negative pressure applied low-level laser probe to optimize laser transmission pattern and therefore, to improve photon density in soft tissue. In order to evaluate the possibility of clinical application of the developed laser probe, ex-vivo experiments were performed with porcine skin samples and laser transmissions were quantitatively measured as a function of tissue compression. The laser probe has an air suction hole to apply negative pressure to skin, a transparent plastic body to observe variations of tissue, and a small metallic optical fiber guide to support the optical fiber when negative pressure was applied. By applying negative pressure to the laser probe, the porcine skin under the metallic optical fiber guide is compressed down and, at the same time, low-level laser is emitted into the skin. Finally, the diffusion images of laser in the sample were acquired by a CCD camera and analyzed. Compared to the peak intensity without the compression, the peak intensity of laser increased about $2{\sim}2.5$ times and FWHM decreased about $1.67{\sim}2.85$ times. In addition, the laser peak intensity was positively and linearly increased as a function of compression. In conclusion, we verified that the developed low-level laser probe can control the photon density in tissue by applying compression, and therefore, its potential for clinical applications.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.178-191
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• 2003

OMC is essentialiy necessary compound in sun goods as organic UV protecting products. But the skin-trouble problem is raising because of skin penetration of OMC. In this study, non-capsulated pure OMC was compared with Organic-Inorganic-Nano-hybrid OMC for skin penetration force and SPF degree. Organic- Inorganic Nano-Hybrid OMC is OMC trapped in the pore of the mesoporous silica synthesized by the sol-gel method after OMC is nanoemulsified in the system of the hydrogenated Lecithin/ Ethanol/caprylic/capric triglyceride/OMC/water. OMC- nano- emulsion was obtained by a microfluidizing process at 1000bar and then micelle size in the nanoemulsion solution is 100-200nm range. Mesoporous silica nano-hybrid OMC was prepared by the process; surfactant was added in dissolved OMC-Nanoemulsion, then the rod Micelle was formed. OMC-nanoemulsion was capsulated in this rod Micelle and then silica precursor was added in the OMC-nanoemulsion solution. Through the hydrolysis reaction of the silica precursor, mesoporous silica concluding OMC-Nanocapsulation was obtained. The nano-hybrid surface of this OMC-Nanoemulsion-Inorganic system was treated with polyalkyl-silane compound. OMC-Mesoporous silica Nano-hybrids coated with polyalkyl-silane compound show the higher sun protecting factor (SPF Analyzer: INDEX 10-15) than pure OMC and could reduce a skin penetration of OMC. The physico-chemical properties of these nano-hybrids measured on the SPF index, partical size, strcture, specific surface area, pore size, morphology, UV absorption, rate of the OMC dissolution using SPF Analyzer, Laser light scattering system, XRD, BET, SEM, chroma Meter, HPLC, Image analyzer, microfluidizer, UV/VIS. spectrometer.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.4
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• pp.349-354
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• 2023

Sunscreen is a product that protects against ultraviolet rays by blocking and scattering ultraviolet rays, and has now become a daily necessity beyond cosmetics. Applying sunscreen is a common and easy way to prevent skin damage caused by ultraviolet rays. Due to its significance, the evaluation of sunscreen has evolved since its regulation by the FDA in 1978, progressing to standardized methods established by ISO. Additionally, to assess the loss of sunscreen due to activities such as water exposure or sweating, the Ministry of Food and Drug Safety in Korea and ISO have established protocols for evaluating the water-resistant sun protection factor (SPF). However, existing evaluations of water resistance have been mainly confined to test methods involving plain water, and methods accounting for the impact of seawater during activities like beach leisure, sports, and recreation are yet to be established. Based on the existing guidelines for testing the water-resistant UV protection index, this study compared the water-resistant UV protection index in water, artificial seawater (salt water) and natural seawater (sea water) to evaluate the UV protection index in real-world situations such as marine leisure, sports, and leisure activities. Through these results, we were able to compare the differences between water resistance sun protection index tests in ordinary water, artificial seawater, and natural seawater, and suggest a method for water resistance sun protection index tests using natural seawater.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.2
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• pp.347-365
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• 2013

The performance of finger-vein recognition methods is limited by camera optical defocusing, the light-scattering effect of skin, and individual variations in the skin depth, density, and thickness of vascular patterns. Consequently, all of these factors may affect the image quality, but few studies have conducted quality assessments of finger-vein images. Therefore, we developed a new finger-vein recognition method based on image quality assessment. This research is novel compared with previous methods in four respects. First, the vertical cross-sectional profiles are extracted to detect the approximate positions of vein regions in a given finger-vein image. Second, the accurate positions of the vein regions are detected by checking the depth of the vein's profile using various depth thresholds. Third, the quality of the finger-vein image is measured by using the number of detected vein points in relation to the depth thresholds, which allows individual variations of vein density to be considered for quality assessment. Fourth, by assessing the quality of input finger-vein images, inferior-quality images are not used for recognition, thereby enhancing the accuracy of finger-vein recognition. Experiments confirmed that the performance of finger-vein recognition systems that incorporated the proposed quality assessment method was superior to that of previous methods.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.64-67
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• 1997

In the total artificial heart(TAH), a transcutaneous information transmission system(TITS) is vely important to monitor the TAH status and detect the device failure, and repair the possible problems. First of all, the communication channel(skin) and method were simulated in terms of transmittance, scattering, reflection and absorption, then the system was designed with size reduction including low power consumption and reliability compared to the previous one. The informations are transmitted through the skin(approximately 1cm in depth) by frequency modulated near infrared(NIR) pulses using 780nm laser diodes as transmitters and photodiode as receiver with high speed and high spectral sensitivity. The logic high and low frequencies are 3MHz, 1MHz respectively. The system is a bidirectional data link for more than 38.4Kbps data rate, full-duplex with a bit error rate of less than $10^{-5}$.

• Geotechnical Engineering
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• v.8 no.3
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• pp.13-22
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• 1992

Model pile tests using calibration chamber are performed in !his paper in order to clarify the effect of the fundamental differences between the newly developed SPLT(Simple Pile Loading Test)and the conventional pile loading test on the pile bearing capacity. They are : (1) the direction of the applied load to mobilize the skin friction ; and (2) the use of reduced sifted sliding core. The conclusions obtained from the model pile tests are as follows : (1) The skin friction in tension loading is found to be somewhat smaller than that in compression loading. The average ration is 0.73 with the coefficient of variation (COV) of 0.18. (2) The ratio of the tip resistance rosin연 the reduced sized sliding core to that using the whole shoe shows wide scattering ; its average is 0.99 and the COV is 0.28. The aver - age of 0.99 means that there is no considerable difference in the tip resistance whether the reduced sized sliding core or the whole shoe is used, on condition that penetration depth ratio is larger than 4 : if the boundary effect of the chamber test is considered, the resistance of the whole shoe might be even larger.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.86-90
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• 2013

Various methods have been proposed for enhancing the contrast of laser speckle contrast image (LSCI) in subcutaneous blood flow measurements. However, the LSCI still suffers from low image contrast due to tissue turbidity. Herein, a physicochemical tissue optical clearing (PCTOC) method was employed to enhance the contrast of LSCI. Ex vivo and in vivo experiments were performed with porcine skin samples and male ICR mice, respectively. The ex vivo LSCIs were obtained before and 90 min after the application of the PCTOC and in vivo LSCIs were obtained for 60 min after the application of the PCTOC. In order to obtain the skin recovery images, saline was applied for 30 min after the application of the PCTOC was completed. The visible appearance of the tubing under ex vivo samples and the in vivo vasculature gradually enhanced over time. The LSCI increased as a function of time after the application of the PCTOC in both ex vivo and in vivo experiments, and properly recovered to initial conditions after the application of saline in the in vivo experiment. The LSCI combined with the PCTOC was greatly enhanced even in deep vasculature. It is expected that similar results will be obtained in in vivo human studies.

• Journal of Pharmaceutical Investigation
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• v.35 no.4
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• pp.233-241
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• 2005

Ursolic acid (UA), a bioactive triterpene acid, has been known to increase collagen content in human skin in addition to other actions such as anti-inflammatory, skin-tumor prevention and anti-invasion. However, it is poorly soluble in water. Therefore, we firstly prepared microemulsion system with benzyl alcohol, ethanol and Cremophor EL, RH 40 and Brij 35 as surfactant in order to increase solubility of UA and then prepared microemulsion was dispersed in o/w cream base for the topical delivery of UA in an effort to improve anti-wrinkle effect. The pseudo-ternary phase diagrams were developed and various microemulsion formulations were prepared using benzyl alcohol as an oil, Cremophor EL, RH 40 and Brij 35 as a surfactant. The droplet size of microemulsions was characterized by dynamic light scattering. The accumulation of VA in the skin from topical cream was evaluated in vitro using hairless mouse skins. The mean droplet size was $26.8{\pm}6.6$ nm for microemulsions II with Cremophor EL. All UA creams showed pseudoplastic flow and hysterisis loop in their rheogram, depending on the type of materials added in topical creams. The in vitro accumulation data demonstrated the UA topical cream prepared with the combination of Poloxamer 407 and Xanthan gum as a copolymer showed higher accumulation percentage than those prepared with either Poloxamer 407 or Xanthan gum. These results suggest that UA topical cream using microemulsion systems may be promising for the topical delivery of UA.