• Journal of Applied Reliability
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• v.7 no.4
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• pp.173-181
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• 2007

Out door exposure to daylight and weather climate conditions can cause adverse effect on the properties of automotive plastic materials. The effects of sunlight exposure, especially ultra violet (UV) radiation, can break down the chemical bonds in a polymeric material. This degradation process is called photo-degradation and ultimately leads to color changes, cracking, chalking, the loss of physical properties and deterioration of other properties. To explore the effect of sunlight exposure on the automotive materials, this study investigated photo-oxidation degree and surface property change of molding parts by analytical methods. For the further study, accelerated weathering test methods are proposed, which can correlate with out door weathering, to predict long term performance of automotive plastic materials.

• The Journal of Korea Robotics Society
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• v.6 no.1
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• pp.18-26
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• 2011

This paper presents a method, Exposure Controlled Temporal Filtering (ECF), applied to visual motion tracking, that can cancel the temporal aliasing of periodic vibrations of cameras and fluctuations in illumination through the control of exposure time. We first present a theoretical analysis of the exposure induced image time integration process and how it samples sensor impingent light that is periodically fluctuating. Based on this analysis we develop a simple method to cancel high frequency vibrations that are temporally aliased onto sampled image sequences and thus to subsequent motion tracking measurements. Simulations and experiments using the 'Center of Gravity' and Normalized Cross-Correlation motion tracking methods were performed on a microscopic motion tracking system to validate the analytical predictions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.891-896
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• 1998

The relaxation and elimination characteristics of polarization-photoinduced dichroism have been investigated in amorphous chalcogenide thin films deposited having normal(0。) and obique (80。) vapor incident angles. The dark relaxation kinetics of dichroism from a saturation point(D\ulcorner\ulcorner) to a certain relaxation point(D\ulcorner\ulcorner) grew to be longer on subsequent cycles of switching on and off of the inducing light, and these decays are changed from simple exponential decay to stretched exponential decay. The dichroism induced by a long time(~3.3 hrs) exposure exhibited the characteristics of longer time maintenance and smaller decreasing rate, in contrast with that by a short time (~min) exposure. In addition, the dichroism was eliminated by the exposure of non-polarized He-Ne laser.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.23-26
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• 1999

Phase separation temperature of lysozyme-water mixture increased with X-ray exposure on lysozyme and decreased with impurity of saponin. The intensity of light scattering in lysozyme-water mixture with X-ray exposure on lysozyme decreased as a function as a function of temperature, and decreased with impurity of saponin.

• Journal of Environmental Health Sciences
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• v.45 no.5
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• pp.405-425
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• 2019

Objective: This study aimed to review the methodologies for evaluation of consumer spray products containing engineered nanomaterials (ENM), particularly focusing on inhalation exposure. Method: Literature on the evaluation methods for aerosolized ENM exposure from consumer spray products were collected through academic web searching. Common methodologies used in the literature, including research reports and academic articles, were also introduced. Results: The number of ENM-containing products have shown a considerable increase over recent years, from 54 in 2005 to 1,827 in 2018. Currently there is still discussion over the existing regulations with regard to product safety. Analysis of both ENM suspensions in the products and their aerosols is important for risk assessment. Comparison between the phases suggests how the size and concentration of particles change during the spray process. To analyze the ENM suspensions, dynamic light scattering, electron microscopy techniques, and inductively coupled plasma with mass spectrometry were used. In the aerosol monitoring, direct-reading instruments have been used to monitor the aerosols and conventional active sampling is used together to supplement the lack of real-time monitoring. There are also some models for estimating inhalation exposure. These models may be used to estimate mass exposure to nanomaterials contained in consumer products. Conclusion: Although there is no standardized method to evaluate ENM exposure from consumer products, many concerns about ENM have emerged. Every potential measure to reduce exposure to ENM from spray product use should be implemented through a precautionary recognition.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.109-113
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• 2004

We have manufactured and characterized the fiber-to-Planar Waveguide Coupler for analysis of the photo-induced refractive index change of DM-BTE .(l,2-bis[2,5-dimethylthio-phen-3-yl]-hexafluorocyclopentene) When irradiated with ultraviolet light, the colorless diarylethene(DM-BTE)-crystal turned red while keeping the crystal shape. The red color was bleached by irradiation with visible light(λ＞450 nm). The resonant wavelength was shifted and recovered owing to the refractive index variation of the planar waveguide because of its photo-functional properties on exposure to UV and visible light. The wavelength responses of this switch by UV exposure were measured as 0.057 nm/sec with saturation time of 60 seconds. and when illuminated by visible light, resonance wavelength variations were measured as 0.028 nm/sec, with recovery time of 140 seconds.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.3
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• pp.391-400
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• 2009

The purpose of this study is to investigate the efficacy of safflower yellow colorant as a natural dye for hair coloring. The dyeing properties of safflower yellow colorant on hair were explored to obtain optimum conditions. Also, the effect of mordant was studied in terms of dye uptake, colorfastness, and hair damage to better understand the characteristics of the colorant. Tensile strength measurement and SEM analysis were carried out for investigating hair damage to light exposure and washing. On the basis of obtained results considering possible hair damage, optimum dyeing conditions were set 100%(o.w.h.) colorant concentration, pH 5, $40^{\circ}C$, and 20min. Dye uptake was improved more effectively by repeated dyeing rather than by increasing concentration. Pre-mordanting method improved dye uptake slightly, irrespective of mordant type. The safflower yellow colorant produced Y colors on hair. Cu and Fe mordants improved washing and light fastness slightly. Better strength retention was obtained with the mordanted-dyed hair than the unmordanted-dyed hair after light irradiation for 40 hours and 10 repeated washing. The hair was more damaged by light exposure than by washing. It was concluded that the safflower yellow colorant can be used as a natural semi-permanent hair dye producing Y color without mordanting.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.271-277
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• 2016

Objectives: In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs) on the degree of conversion (DC) and the mechanical properties of resin cements. Materials and Methods: Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG), according to the different radiant exposures (5, 10, and $20J/cm^2$) and two LCUs (single-peak and polywave). The specimens were made (7 mm in length ${\times}$ 2 mm in width ${\times}$ 1 mm in height) using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E) by a three-point bending test. Data were assessed for normality, after which two-way analysis of variance (ANOVA) and post hoc Tukey's test were performed. Results: No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. Conclusions: On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was material-dependent.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.267-271
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• 2018

A high directivity TIR (total internal reflection) lens in the UV-A region was designed using a silicone resin, and a UV light source module with a maximum irradiation density of $150mW/cm^2$ was fabricated. The beam angle of the TIR lens was designed to be $8.04^{\circ}$ and the maximum diameter of the TIR lens was Ø13.5. A silicone resin having a UV transmittance of 93% and a refractive index of 1.4 at a wavelength of 365 nm was used, and the lens was manufactured using an aluminum mold, from which silicone could be easily released. The module was fabricated in a metal printed circuit board of COB (chip on board) type using a $0.75{\times}0.75mm^2$ UV chip. A jig was used to adjust the focal length between lens and chip and to fix the position of the lens. The optical characteristics such as illumination distributions of the lens and module were designed using 'LightTools' optical simulation software. The heat dissipation system was designed to use a forced-air cooling method using a heat-sink and fan.

• Journal of Environmental Science International
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• v.33 no.7
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• pp.501-509
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• 2024

Prunus mume is a culturally significant fruit tree in East Asia that is widely used in traditional foods and medicines. The present study investigated the effects of sunlight exposure and leaf position on the photosynthetic efficiency of P. mume using SPAD values. The study was conducted at Cheongju National University of Education, Korea, under contrasting conditions between sunny (Site A) and shaded (Site B) areas on P. mume trees. Over three days, under varied weather, photosynthetic photon flux density (PPFD) and SPAD measurements were collected using a SPAD-502 plus chlorophyll meter and a smartphone PPFD meter application. The SPAD values of the 60 leaves were measured in triplicate for each tree. The results indicated that trees in sunny locations consistently exhibited higher SPAD values than those in shaded areas, implying greater photosynthetic efficiency. Moreover, leaves positioned higher in the canopy showed increased photosynthetic efficiency under different light conditions, underscoring the significance of leaf placement and light environment in photosynthetic optimization. Despite the daily sunlight variability, these factors maintained a consistent influence on SPAD values. This study concludes that optimal leaf positioning, influenced by direct sunlight exposure, significantly enhances photosynthetic efficiency in P. mume. These findings highlight the potential of integrating smart farming techniques, especially open-field smart farming technology, to improve photosynthesis and, consequently, crop yield and efficiency. The findings also highlight the need for further exploration of environmental factors affecting photosynthesis for agricultural advancement.