• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.53-68
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• 2004

Protein deposit buildup on soft contact lenses(SCLs) is responsible for discomfort, optical defects and is even damaging to the eye. To better understand protein deposit formation on SCL, we investigated the pattern of protein attachment on patient-worn SCLs and the effect of the protein on the contact angle of SCLs and the transmission of visible light. This study used data from a clinical trial where subjects wore either daily-wear SCL(etafilcon A, N=40) for various period up to 14 days, or extended-wear SCL(balafilcon A, N=40) for 8 h day or night. The adsorption of protein in daily-wear SCLs was significantly increased in patient-worn time-dependent manner although the lenses were cleaned everyday by using the multi-purpose SCL solution. After 2 weeks wearing, the protein on the SCL influenced the contact angle of the lenses. Furthermore, the transmission of visible light of the lenses decreased up to almost 7%. Extended-wear SCLs worn during the closed eye condition were found to deposit significantly more protein than SCLs worn during the open eye condition. The amounts of protein adsorbed both after daily SCL wear and after overnight SCL wear were not affected the contact angle and the transmission of visible light of the lenses. The protein deposit buildup on SCL related to the corneal temperature and pH of tear fluid.

• Korean Journal of Environment and Ecology
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• v.7 no.1
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• pp.10-21
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• 1993

Artificial acid rain (pH 3.0, 4.0 and 5.0) and ground was treated on the seeded pots of 4 species to examine its effects on germination and survival rate, seedling growth and contact angles on needle surface. Artificial acid rain was prepared by diluting sulfuric acid with ground water and ground water (pH 6.5) was used as control. Artificial acid rain was sprayed to seeded pots two or three times per week for growing season, one times per week for winter seasons. About 5mm of artificial acid rain was treated each time from early April, 1991 to early October, 1993. Germination and survival rate, soil acidity, seedling growth and contact angles on the needle surface were measured and compared among the treatments. The results were summarized as follows ; Artificial acid rain might have positive effects on growth-related characteristics of the seedlings in the first and second year of acid rain treatment, and the effects were differed among four species. All growth-related characteristics of the seedlings in third year, however, decreased with decrease of pH values of artificial acid rain. This was considered to the results of acidic accumulation over soil buffer capacity. Needle injury and biomass (defoliation) was correlated with the pH values of artificial acid rain, and this character might be a good criteria for early diagnosis of acid rain injury. The differences of soil acidity were significant among the treatments for all species. Contact angles between needle surface and water droplet decreased with decrease of pH values of artificial acid rain. Measuring and comparing contact angles might be very good criteria for early diagnosis of acid rain injury.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.256-261
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• 2009

Hydrophilic and transparent $TiO_2$ thin film was fabricated by sol-gel method and the properties of contact angle, surface morphology, and transmittance were measured. In addition, surfactant Tween 80 was used for increasing the hydrophilic property of thin film. When the contents of Tween 80 in $TiO_2$ solution was 0, 10, 30, 50wt%, the contact angles of $TiO_2$ thin film were $41.4^{\circ}$, $18.2^{\circ}$, $16.0^{\circ}$, $13.2^{\circ}$, respectively. Fabricated $TiO_2$ thin film showed the photocatalytic property that decomposed methylene blue and decreased the absorbance of solution after UV irradiation. $TiO_2$ thin films fabricated with the solution of 30 wt% Tween 80 were deposited on glass (bare), antimony tin oxide (ATO), fluorine tin oxide (FTO), indium tin oxide (ITO) coated glass substrates, and the contact angle and transmittance of thin film was measured. The contact angles of thin films deposited on four substrates were $16.2\sim27.1^{\circ}$ and was decreased to the range of $13.2\sim17.6^{\circ}$ after UV irradiation, Especially, the thin films coated on ATO and FTO glass substrate showed high transmittance of 74.6% in visible range, respectively, and low transmittance of 54.2% and 40.4% in infrared range, respectively.

• Korean Journal of Environment and Ecology
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• v.7 no.2
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• pp.252-269
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• 1994

This study was conducted to the early diagnosis of injuries on needles of conifer by acid rain and air pollutants in metropolitan area, Korea. It was executed to calculate of injured index, contact angle measurement, nutrient content analysis in needles, analysis of soil chemical properties from June 1990 to June 1991. The sensitive species (Picea abies, Abies holophylla) for acid rain and air pollutants were used as the study materials. And the results from this study were as follows : Degree of Injured index was divided into three groups in June 1990. The first group (not injured sites) was Kwangnung and Yangpyung. The Second group (slight injured sites) was Inchon, Boramae Park, Kwachun, Seoul Women's Univ., Anyng, and Yangsuri. The third group (serious injured sites) was Namsan, Seoul City Univ., Children's Park, and Kumgok Royal Tomb. But, Inchon, Kwachon area were changed from slight injured areas to serious injured areas in December 1990. As time goes on, the degree of injured gets worse. In contact angle analysis, value of December 1990 was lower than that of June 1990, especially, that of two-year-needle were lower than of one-year-needle. The correlation between injured Index and contact angle was significantly negative. In the result of needle nutrients analysis of Picea abies, Abies hozophylla, Ca, Mg, K contents was higher in December 1990 than that in June 1991 and that of one-year-needle were prominantly higher than that of two-year-needle. In case of wax quantity analysis in injured area, the older the leaf age is, the smaller the contented wax quantity is. In injured area, the higher a leaf age is, the much that of index is. As a result, the method of analysis referred in the former, is applied by a complementary cooperation. That of method is done sustainably in the future, the correct results will be expected.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.177-184
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• 2019

Non-fluorinated water repellent coating solutions were obtained using methyltrimethoxysilane (MTMS) and trimethylethoxysilane (TMES) as precursors. The solutions were spin-coated on a cold-rolled steel sheet and cured thermally to prepare water repellent coating films. During this process, the effect of molar ratio of TMES/MTMS was studied for the hydrophobic properties of the coating films. Hydrophobic properties of coating films were characterized using contact angle measurement, surface morphology analysis and infrared spectroscopy. When the molar ratio of TMES/MTMS was varied from 0 to 30, the contact angle of the un-coated cold-rolled steel sheet was $30^{\circ}$, whereas when the molar ratio of TMES/MTMS was 1, the contact angle increased to $104^{\circ}$ and water repellency was significantly improved. In the case of TMES/MTMS molar ratios of 10, 15, 25 and 30, the contact angles of coating films showed $109^{\circ}$, $114^{\circ}$, $117^{\circ}$ and $144^{\circ}$, respectively. At this time, the hydrophobicity of the coating films was improved by the increase of the surface roughness and the content of the methyl component at the coating surface. In particular, when the molar ratio of TMES/MTMS was 30, the overall surface roughness was greatly increased due to the presence of surface particles as well as the water repellency due to methyl groups of TMES, resulting in super hydrophobicity of $144^{\circ}$.

• Journal of the Korean Geosynthetics Society
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• v.22 no.4
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• pp.43-49
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• 2023

This study described the test results to evaluate the effect of fines content on the wettability of sandy soil composed of hydrophobic soil particles. Wettability was evaluated using the contact angle obtained from the water drop test results for Jumunjin standard sand and sandy soil containing fines content. The test results showed that the wettability of sandy soil composed of sand and fine-grained soil changed depending on the hydrophobic level and fines content. The influence of fines content on the wettability of sandy soil was analyzed. It was found that 1% and 3% hydrophobic sandy soil with 5% fines content decreased by 94.4% and 32.4%, respectively, compared to the contact angle of standard sand. In addition, the contact angle reduction ratio for sandy soil with a 5% hydrophobic level and a fines content of 5% and 10% were 24.4% and 37.3%, respectively. In other words, the wettability of the soils should be evaluated considering the fines content to predict the behavior of contaminants, because the fines content has a significant impact on the value and increase/decrease ratio of the contact angle of sandy soil

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.160-167
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• 2007

전자상거래에서 핵심적인 연구질문 중의 하나는 서비스품질에 영향을 주는 핵심 driver가 무엇인가를 이해하는 것이다. 이 연구에서는 인터넷 쇼핑몰의 관리기능 변수를 파악하고 그것이 서비스품질의 4개의 각 세부요소에 어떻게 영향을 끼치는가를 조사한다. 본 연구에서는 기존문헌을 토대로 서비스품질의 각 세부요소에 영향을 미치는 7개의 선행변수를 도출하였다:배달(delivery), 제품반품(reverse logistics), 불만처리(claim resolving), 추천(recommendation), 고객맞춤화(customization), 상호작용성(interactivity), 접촉(contact). 실증적 테스트결과 이 선행변수들은 모두 서비스품질의 각 세부요소에 유의한 결과를 나타냈으며 이는 어떻게 서비스품질의 수준이 관리될수 있는지에 대한 이해를 돕는데 도움을 줄 것이다.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.403-406
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• 2006

본 연구에서는 양극의 two-phase simulation 모델을 확립하고 GDL 물성과 작동조건이 전지성능에 미치는 영향에 대해 시행하였다. 모델로는 Multi-phase $mixture(M^2)$ 모델을 사용하였는데 이 모델은 각 상의 balance식을 하나의 mixture-phase식으로 통합하여 수학적 계산이 용이할 뿐만 아니라 실제 전지 성능에 매우 근사하여 신뢰성성도 확보할 수 있었다. 최적의 GDL 구조와 작동조건을 규명하기 위해 기체투과도, 접촉각, 기공도, 기체 공급가스 차이에 따른 전지 성능 분석을 시행하였는데 그 결과 모든 파라미터들이 증가할수록 비례적으로 전지 성능이 증가하였다. 기체 공급가스>기공도>>접촉각>기체투과도 순으로 전지에 미치는 영향이 큰 것으로 나타났다.

• 보존과학연구
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• s.32
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• pp.5-24
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• 2011

Neunghwaji(Embossed patterned paper) is a unique paper used for a traditional book cover in Korea. The research was carried out to investigate Neunghwaji's features. Physical property was studied through a test of tensile strength and folding endurance. Also, comparative analysis of virus resistance and waterproof ability was undertaken on Neunghwaji. 1. Folding endurance test showed that strength of non-embossed CB and HB decreased during deteriorating duration. Embossed CN and HN showed the strength increasing at early stage and decreasing from the 27th day of the deteriorating duration. Tensile strength was decreasing in both cases as deterioration progressed. 2. Growth of Arthrinium sp. fungus on embossed paper was 10% less than plain paper while Cladosporium sp. showed 20~30% less growth. Amur cork dyeing(H) showed 10~30% lower fungi growth than Gardenia seed dyeing(C). The result indicated that embossed paper has better virus resistance than Hanji, and Amur cork dyeing has better virus resistance than Gardenia seed dyeing. 3. Average contact angle of CN, CB, HN, and HB was $85{\sim}92^{\circ}$ and NON-N and NON-B was $59{\sim}63^{\circ}$. In detail, CN's contact angle was $1{\sim}7^{\circ}$ higher than CB's; HN was $1{\sim}6^{\circ}$ higher than HB. Therefore, it was found that embossed paper has higher contact angle than Hanji thus the former has better waterproof ability. The research suggested production technique of Neunghwaji and studied its features related to the technique. Neunghwaji was confirmed to have superior quality to Hanji though further study regarding above test result is needed to complement the research.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.583-588
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• 2015

Asymptotic method has been often used to theoretically analyze the complete contact problem. The error of the asymptotic results increases as the distance from the contact edge increases. The singularity cannot be properly obtained from a finite element (FE) analysis owing to the finiteness of the element size. In the present work, the complete contact problem in bonded condition is analyzed using a combined experimental-numerical approach to assist and/or compare with the asymptotic results. Al and Cu alloys are used for the material combination of the punch and substrate. 120 and 135 degrees are used for the punch angle. The FE models are validated by comparison of displacement distributions obtained by the FE analysis and $moir{\acute{e}}$ experiment. Generalized stress intensity factors are evaluated using the validated FE models. Stress field in the vicinity of the sharp contact edges obtained from the FE and asymptotic analyses are compared. The discrepancies are also discussed.