• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.114-120
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• 2006

Nano-size Au particle doped $TiO_2$ films were prepared with $Ti(OC_3H_7^i)_4$, polyvinylpyrrolidone(PVP), $HAuCl_4$ and $C_3H_7OH$ etc. by sol-gel method. $TiO_2$ gel films were obtained by the dip-coating method on the $SiO_2$ glass substrates, and then heat-treated at $700^{\circ}C$ for 10 min. The thickness of $TiO_2$ films were $0.7\~1.8\;{\mu}m$. It was found that the thickness of films prepared from PVP containing solution was about $2\~8$ times higher values than that of thin films without PVP. The size of Au particles doped in the films were about $350\~750\;nm$. Nano-size Au particle dispersed $TiO_2$ films showed high absorption peak at visible region 450nm, which made them good candidates for non-linear optical materials and photo-catalytic materials. The contact angle of $TiO_2$ film for water was $12.5^{\circ}$, and therefore it is clear that $TiO_2$ films have very high hydrophilic properties and the self-cleaning effects.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.108-114
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• 2018

Degradations of durability and aesthetic performance in concrete happen during service life due to surface deterioration and dirt stains. Recently, many researches have been performed on self-cleaning and surface enhancement through surface impregnant using photocatalytic reaction with VOCs(Volatile Organic Compounds) removal. This paper is for preliminary study on surface impregnation with silicate and photocatalysis - $TiO_2$. For the work, two types of silicate based impregnants(CS - Coloidal Silica and SC - Sodium Alumina Silicate) are considered. Several tests for viscosity and surface tension are performed, and pull-off test on impregnated concrete is performed. For the surface impregnated concrete, $TiO_2$ is absorbed through submerging and spraying conditions. Through compressive strength test and SEM analysis, it is evaluated that spraying $TiO_2$ on surface impregnated concrete after 30min. of drying period is very effective both for strength enhancement and surface densification.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.425-428
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• 2013

In this paper, we present a novel hydrophilic coating material (Wellture Finetech, Korea) which can be utilized as a coating layer for anti-contamination for electrical and electronic system. The coating material was deposited on 4 inch silicon wafer with several different film thickness. The film thickness was controlled by spin coating speed. After curing of the film, we have scratched by permanent marker to check self-cleaning property of the film. Also we have executed several mechanical tests of the films. As the spin coating speed is increased, the film thickness was thinned from 230 nm to 125 nm. Contact angle of the film was lowered from $30^{\circ}$ to $12^{\circ}$ as the spin coating speed is increased from 700 to 2,500 rpm. On permanent marker scratched film surface coated at 1,000 rpm, we have poured regular city water to investigate self cleaning property of the film. The scratches were gradually separated from the film surface due to super-hydrophilicity of the film. Hardness of spin coated film was 9H measured by ASTM D3363 method. and adhesion of all film was 5B tested by ASTM D3359 method. Also, to get exact hardness value of the film, we have utilized a nano-indenter. As spin speed is increased, the hardness of film was increased from 3 GPa to 5 GPa.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.281-281
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• 2012

연꽃잎 효과(Lotus effect)라 불리는 자가 세정 효과(self cleaning effect)는 연꽃이 항상 깨끗한 상태를 유지하는 것이 관찰되면서 꾸준히 관심에 대상이 되어 왔었다. 자가 세정 효과는 접촉각 $150^{\circ}$ 이상의 초소수성 표면에서 구현이 가능하며 이런 표면을 일상생활부터 산업분야까지 응용하고자 하는 많은 노력들이 있었다. 물질의 친수성 또는 소수성은 표면의 거칠기(roughness)와 표면에너지(surface energy)의 두 가지 특성에 의해 결정된다. 하지만 낮은 표면에너지 물질을 사용해도 접촉각 $150^{\circ}$ 이상의 초소수성 표면을 얻긴 힘들며, 표면의 거칠기를 증가시켜야 한다. PTFE (polytetrafluoroethylene)는 낮은 표면에너지를 가진 소수성 물질로 bulk일 경우 접촉각이 약 $108^{\circ}$이지만 거친 표면을 가진 박막으로 만들 경우 접촉각이 $150^{\circ}$ 이상의 값을 가지는 초수수성 표면이 가능한 물질이다. 특히, 초소수성 표면 이외에 우수한 내열성 및 내화학성 특성을 가지고 있어 디스플레이 및 태양전지 등의 자가세정(self cleaning) 보호막으로써 응용이 기대되고 있다. 본 연구에서는 HFPO (hexafluoropropylene)를 원료 가스로 이용하여, Si(100)과 유리 기판위에 Cat-CVD (Catalytic Chemical Vapor Deposition)법으로 PTFE 박막을 증착하였다. 텅스텐(W)을 촉매로 사용하였으며, 촉매온도가 $850^{\circ}C$이상인 조건에서 접촉각이 $150^{\circ}$ 이상인 초소수성 PTFE 표면을 쉽게 얻을 수 있었다. 특히 본 연구에서는 제막압력을 300 mTorr에서 700 mTorr까지 변화시켜 가며 유리와 Si 기판위에 증착하였다. Cat-CVD 제막압력을 변화시켜가며 증착된 PTFE 박막의 접촉각을 측정한 결과, 제막압력이 300 mTorr일 때 glass와 Si 기판위에 증착된 PTFE박막 표면에서의 접촉각은 각각 133, $117^{\circ}$였지만, 제막압력이 400 mTorr이상일 땐 $150^{\circ}$ 이상의 높은 접촉각을 갖는 초소수성 표면을 얻을 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.309-316
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• 2016

In this study, sewage was fed with up flow direction into a reactor equipped with a screw to circulate media that had lower specific gravity than water. It was observed that the media in the reactor could be circulated by a screw with reverse flow of the sewage feeding from the top to the bottom direction. Under these conditions, concentrations of inflow and outflow pollutants were measured at the filtration unit. Experimental results revealed stable circulation of the media with a screw in the reactor. Circulation of the media in the reactor showed more efficiency in removing the pollutants (particulate matters and organics) than no circulation. The maximum removal efficiencies of suspended solid (SS), chemical oxygen demand (CODmn), and total phosphorus (T-P) were 96%, 72% and 65%, respectively. Improvements for SS, CODmn and T-P removals with circulation of media were 52.38%, 43.14% and 118.12% respectively, compared to those without circulation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.1-8
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• 2023

Marine and hydraulic structures are subject to durability damage not only due to the penetration of sea water but also due to the attachment of marine organisms. Therefore, in this study, we tried to develop an antifouling coating agent with self-cleaning function for marine concrete. It was confirmed that the antifouling coating agent mixed with AKD, cellulose nanofibers and BADGE had sufficient antifouling performance at a well hydrophobicity of around 140° in contact angle and an inclination angle of 15°. In the abrasion resistance test of the surface, only a maximum loss of 0.015 g occurred. In the durability test, as a result of the chloride ion permeation test, almost no chloride ion permeation occurred in the variable where the coating agent was applied, and carbonation and freeze-thaw damage also rarely occurred, so it was analyzed that it was effective in securing durability of concrete.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.179-199
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• 2012

Purpose: This study was conducted to prepare the fundamental data on oral hygiene of the elderly and to assess the behavior of oral hygiene, subjective oral health, oral health problem among the elderly, and to contribute to successful enhancement of life in their declining years. Methods: The author surveyed the behavior of oral hygiene, subjective oral health, oral health problem to 192 elderly at a health center of Busan using structured self- administered questionnaire from Nov. 2nd 2009 to Feb. 10th 2010. Collected data were analysed by SPSS WIN 18.0 statistical program for frequency, percentage production, ${\chi}^2$ (Chi-square) verification, t-test, One-way ANOVA, Logistic Regression. Results: The distribution of total subjects by oral health behaviors were 56.8% for "have ever trained how to tooth brushing", 76.6% for "correctly performed tooth brushing by himself ", 71.8% for "tooth brushing a day is two times and less", 87.5% for "it doesn't tooth brushing in meals and after" and 53.6% for "it doesn't use the facility for oral health", respectively. The distribution of total subjects by the state of perceived oral health were 51.0% for "feel the oral discomfort", 51.6% for "feel the comfortable chewing on starchy food", respectively. The mean point of perceived oral health by general characteristics of total subjects were statistically significant difference in sex, type of medical insurance, smoke, exercise, and chronic disease. The mean point of perceived oral health by oral health behaviors of total subjects were statistically significant difference in educational experience on tooth brushing, recognition for tooth brushing by himself, tooth brushing a day, and tongue cleaning. The risk factors of perceived oral health were type of medical insurance and chronic disease in general characteristics, tooth brushing in meals and after and tooth brushing a day, and tongue cleaning in oral health behaviors. Conclusion: The author recommend to the prevention of chronic disease, carry out the tooth brushing in meals and after, three times and over tooth brushing a day and tongue cleaning for oral health. and the author consider that it need to prepare the active countermeasure to oral health such as reeducation for oral health and supply to the tongue cleaner.

• Journal of Fashion Business
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• v.26 no.1
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• pp.92-104
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• 2022

The nail service field, which has emerged as a new trend in the beauty industry, is showing rapid growth compared to other beauty fields. As nail beauty services become more common and popular, studies on related fields are also actively progressing, but most of the research has been focused on changes on self-esteem. In addition, most of the preceding studies are centered on female customers, thus, there is little data on male customers that are increasing recently. This research aims to provide customized marketing data to the nail beauty service industry by analyzing the psychological characteristics of the customers and their motives by selecting self-esteem and confidence as factors. First, the customers' confidence and self-esteem were classified into a group with high and low confidence and self-esteem, and as a result of analyzing the difference in service pursuit benefits and revisit intentions, there were significant differences in mood change, professionalism, health hygiene, aesthetics, and revisit. Second, as a result of analyzing the effect of the service pursuit benefits of male and female customers on the revisit intention, it was found that only health and hygiene had a significant effect on the revisit intention. Female customers also had a significant influence on their revisit intention, which is judged to have a significant effect on male customers' revisit intention because most of the main management is cuticle cleaning, callus management, and problematic nails.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.4
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• pp.451-460
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• 2021

Objectives: The purpose of this study is to examine occupational risk factors that affect the mental health (depression, anxiety, anger, insomnia, self-esteem, trauma) of hospital facility workers. Methods: A survey was conducted from November 17, 2020 to December 1, 2020 for 700 non-medical workers (Temporary and contract workers: cleaning, security, information, office workers, etc.) working at a general hospital in Seoul. Results: As a result of the study, the risk of musculoskeletal disorders was found to have a significant effect on depression, anxiety, insomnia, and trauma. Noise had a significant effect on depression and anger, dust hazard had an effect on depression and self-esteem, and high temperature had a significant effect on anxiety and insomnia. Conclusions: Based on these results, it is necessary to examine the influence of occupational risk factors to improve the mental health of non-medical hospital facility workers.

• Restorative Dentistry and Endodontics
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• v.48 no.3
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• pp.28.1-28.13
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• 2023

Objectives: This study aimed to investigate the effect of the application method of 2% chlorhexidine (CHX) and its influence on the adhesion of fiberglass posts cemented with a self-adhesive resin cement. Materials and Methods: Sixty human mandibular premolars were endodontically treated and divided into 5 groups (n = 12), according to the canal irrigant and its application method: 2 groups with conventional syringe irrigation (CSI)-2.5% sodium hypochlorite (NaOCl) (control) and 2% CHX- and 3 groups with 2% CHX irrigation/activation-by passive ultrasonic irrigation (PUI), Easy Clean file, and XP-Endo Finisher file. Two roots per group were evaluated for smear layer (SL) removal by scanning electron microscopy. For other roots, fiber posts were luted using a self-adhesive resin cement. The roots were sectioned into 6 slices for push-out bond strength (BS) (7/group) and nanoleakage (NL) (3/group). Data from SL removal were submitted to Kruskal-Wallis and Student-Newman-Keuls tests (α = 0.05). Data from BS and NL were evaluated by 2-way analysis of variance and Tukey's test (α = 0.05). Results: For SL removal and BS, the CHX irrigation/activation promoted better values than CSI with CHX (p < 0.05), but it was not significantly different from CSI with NaOCl (p > 0.05). For NL, the lowest values were obtained by the chlorhexidine irrigation/activation groups (p < 0.05). Conclusions: Active 2% CHX irrigation can be used to improve the post space cleaning and adhesion before fiber post cementation with self-adhesive resin cements.