• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.2
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• pp.183-189
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• 2018

Blue light is the highest energy wavelengths in the visible light region and induces skin aging and active oxygen. Studies on harmful mechanism of skin are under way. Research on blue light blocking materials in cosmetics and formulation studies are in the early stage, and the test methods related to blue light blocking measurement are not established. The blue light blocking efficacy was established by referring to the test method of the sunscreen in vitro test(COLIPA guideline, ISO 24443, FDA Final Rule on Sunscreen Testing and Labeling). The blue light blocking effect was evaluated for 17 kinds out of 27 kinds of sunscreen raw materials suggested in KFDA guideline. The Effect was 14.97% for zinc oxide and 16.32% for bishexyloxyphenol methoxyphenyl triazine, 35.47% for methylene bis-benzotriazolyltetramethylbutylphenol, and 65.96% for titanium dioxide. In addition, the effect of micro-titanium dioxide was twice as high as that of the nano-titanium dioxide. The results suggested that the light blocking effect test method can be used to search for blue light blocking materials and study cosmetic formulations.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.599-604
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• 2020

Since Corona 19, awareness about antibacterial bacteria has changed. Hand washing after going out became a necessity. Also, fogging occurs a lot on the glasses depending on the wearing of the mask. This problem has caused a lot of discomfort in our daily life and changed our perception of antibacterial and anti-fogging. Therefore, in this study, we studied whether mugwort extract is effective in preventing antibacterial and fogging. To obtain the mugwort extract, mugwort was dried, alcohol extracted, and freeze-dried. An antibacterial test was performed using a mixture of mugwort extract, zinc oxide and natural zeolite mixed in 3:7, and a fogging test was performed using mugwort extract and other mixtures. As a result, in the case of E. coli and K. pneumoniae, which were used as test strains in the antibacterial test, the bacteria were not cultured from the medium added with 1% mugwort extract, and the antibacterial activity against representative Gram-negative bacteria was confirmed. In the anti-fog test, a 10 wt% mixture of mugwort extract showed very good results in both the hot and cold parts. We expect the mugwort extract to be effective in antibacterial and anti-fogging, thus helping to overcome Corona 19.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.4
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• pp.381-390
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• 2017

This study was conducted to determine 16 preservatives and 18 UV filter ingredients levels in 100 sunblock products. The order of detection rates of preservatives was phenoxyethanol (n=61), benzoic acid (n=19), methyl paraben (n=11), benzyl alcohol (n=8), propyl paraben (n=7). Also the order of detection rates of UV filter ingredients was titanium dioxide (n=81), ethylhexyl methoxycinnamate (n=69), zinc oxide (n=48), ethylhexyl salicylate (n=48), bis-ethylhexyloxyphenol methoxyphenyltriazine (n=44). The content of the detected preservatives and UV filter ingredients was within maximum allowed amount established by KFDA. In addition, preservatives and UV filter ingredients, which were not labeled in the products, were detected in 31 and 2 products respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.4
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• pp.289-296
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• 2021

In this study, 27 inorganic sunscreens and 23 sunscreens for children were collected to investigate the use and incorporation of 17 types of sunscreen agents, 13 types of preservatives, and 5 types of heavy metals. As a result, sunscreen agents were detected in the order of titanium dioxide (41 cases), zinc oxide (29 cases), bis-ethylhexyloxyphenyltriazine (10 cases), ethylhexyl salicylate (8 cases), and ethylhexylmethoxynamate (8 cases), and preservatives were detected in order of phenoxyethanol (6 cases), benzoic acid (1 case), and dihydroacetic acid(1 case). All of the identified sunscreen agents were suitable for labeling, but phenoxyethanol, a preservative component other than labeling, was detected at a concentration of 0.1%. Heavy metals such as lead, cadmium, arsenic, antimony, and nickel were not detected or were detected at various concentrations of less than 3.6 ㎍/g. All the detected UV filters, preservatives, and heavy metals were less than the allowed maximum amount stipulated by the Regulations on Cosmetic Safety Standards in Korea.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.521-524
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• 2012

We report on variations of electrical properties with different active layer thickness and post-annealing temperature in amorphous In-Ga-Zn-O (IGZO) thin-film transistors (TFTs). In particular, subthreshold swing (SS) of the IGZO-TFTs was improved as increasing the active layer thickness at an given post-annealing temperature, accompanying the negative shift in turn-off voltage. However, as increasing post-annealing temperature, only turn-off voltage was shifted negatively with almost constant SS value. The effect of the active layer thickness and post-annealing temperature on electrical properties, such as SS, field effect mobility and turn-off voltage in IGZO-TFTs has been explained in terms of the variation of trap density in IGZO channel layer and at gate dielectric/IGZO interface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.5
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• pp.349-352
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• 2010

Thin-film transistors (TFTs) were fabricated using amorphous indium gallium zinc oxide (a-IGZO) channels by rf-magnetron sputtering at room temperature. We have studied the effect of oxygen partial pressure on the threshold voltage($V_{th}$) of a-IGZO TFTs. Interestingly, the $V_{th}$ value of the oxide TFTs are slightly shifted in the positive direction due to increasing $O_2$ partial pressure from 0.007 to 0.009 mTorr. The device performance is significantly affected by varying $O_2$ ratio, which is closely related with oxygen vacancies provide the needed free carriers for electrical conduction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.9
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• pp.693-696
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• 2011

Recently, amorphous oxide semiconductors (AOSs) based thin-film transistors (TFTs) have received considerable attention for application in the next generation displays industry. The research trends of AOSs based TFTs investigation have focused on the high device performance. The electrical properties of the TFTs are influenced by trap density. In particular, the threshold voltage ($V_{th}$) and subthreshold swing (SS) essentially depend on the semiconductor/gate-insulator interface trap. In this article, we investigated the effects of Ar plasma-treated $SiO_2$ insulator on the interfacial property and the device performances of amorphous indium gallium zinc oxide (a-IGZO) TFTs. We report on the improvement in interfacial characteristics between a-IGZO channel layer and gate insulator depending on Ar power in plasma process, since the change of treatment power could result in different plasma damage on the interface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.674-677
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• 2011

The dependency of sputtering power on the electrical performances in amorphous HIZO-TFT (hafnium-indium-zinc-oxide thin film transistors) has been investigated. The HIZO channel layers were prepared by using radio frequency (RF) magnetron sputtering method with different sputtering power at room temperature. TOF-SIMS (time of flight secondary ion mass spectrometry) was performed to confirm doping of hafnium atom in IZO film. The field effect mobility (${\mu}FE$) increased and threshold voltage ($V_{th}$) shifted to negative direction with increasing sputtering power. This result can be attributed to the high energy particles knocking-out oxygen atoms. As a result, oxygen vacancies generated in HIZO channel layer with increasing sputtering power resulted in negative shift in Vth and increase in on-current.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.1
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• pp.17-22
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• 2011

ZnO-based thin-film transistors (TFTs) have been fabricated and the mechanical characteristics of electric circuits, such as stress, strain, and deformation are analyzed by the finite element method (FEM). In this study, a mechanical-stability design guide for such systems is proposed; this design takes into account the stress and deformation of the bridge to estimate the stress distribution in an $SiO_2$ film with 0 to 5% stretched on 0.5-${\mu}m$-thick. The predicted buckle amplitude of $SiO_2$ bridges agrees well with experimental results within 0.5% error. The stress and strain at the contact point between bridges and a pad were measured in a previous structural analysis. These structural analysis suggest that the numerical measurement of deformation, SU-8 coating thickness for Neutral Mechanical Plane (NMP) and ITO electrode size on a dielectric layer was useful in enhancing the structural and electrical stabilities.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1517-1527
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• 2020

This study is about the UV protection effect and water resistance of a multiple emulsion (W/O/W) sunblock cream applied with emotional engineering and reports an actual industrial case. Multiple emulsion system of sunblock cream has the characteristics of changing to a W/O type that is soft and moist when applied, and has excellent water resistance after absorption. Multiple emulsion cream is a highly functional sunblock cream that has both moisture and water resistance. It is a stable milky white cream with a viscosity of 36,000 cps. The organic sunscreen used for the sunscreen was ethylhexylmethoxycinnamate and bisethylhexyloxyphenolmethoxyphenyltriazine. Hexagonal zinc oxide and titanium dioxide that block both UVB and UVA were used. As a result of measuring the UV protection effect by the in-vitro method, the UV protection effect (SPF) is 78.9 for multiple emulsion cream, 76.7 for W/O cream, and 71.3 for O/W cream. It was found that the blocking effect was different. This obtained the highest effect value in the multiple emulsion. As a clinical (in-vivo) result of the UV protection effect, the SPF value representing the UV protection effect of the sunblock cream developed with a multiple emulsion system was 85.7, and the PA-value that blocks the UVA area was 26.5, and ++++. It was found that it has a corresponding high blocking effect. As a result of the water resistance test, the W/O/W formulation had a high waterproofing resistance of 93.8% even after 4 hours, W/O had 75.4%, and O/W had a low water resistance of 25.3%. In the results of the HUT test, it was found in the order of multiple emulsion sun block cream > hydrophilic cream > lipophilic cream. Based on the research results of this multiple emulsion, it is expected to be highly active as a sunblock cream dedicated to outdoor activities by improving the feeling of use, UV protection index, and water resistance. Therefore, in this study, a multiple emulsion system of sunblock cream is developed and has a characteristic that changes to a W/O type that has a soft and moist feeling when applied, and has excellent water resistance after absorption.