• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.345-351
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• 2010

The purpose of this study is to compare microleakage and penetration depths of sealants applied in carious and sound fissures. Extracted premolars(n=80) were divided into 4 groups according to caries status. 1; sound, 2; stained, 3; initial caries, 4; enamel caries. Sealants were applied to the occlusal groove as per manufacturers' instructions, and specimens were thermocycled, stained, sectioned, and examined for microleakage and penetration ability. The results of the present study are as follow: 1. It showed significantly higher microleakage scores in group I than group Two, Three, Four(p<0.05), but no significant difference was found between group Two, Three, and IV(p>0.05). 2. It showed significantly higher penetration scores in group Four (p<0.05), followed by group One, Two, Three, but no significant difference was found between group One, Two, and Three(p>0.05). Based on the results of present study, when the borders of the fissure sealant are on carious enamel, a significantly higher microleakage must be expected. It is considered that depth of enamel caries in the fissure should be taken into account when applying a fissure sealant.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.289-295
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• 2002

Crab shell 충진 칼럼을 이용한 수중 중금속의 연속적 제거에 있어서 여러 중금속 ($Pb^{2+}$ , $Cd^{2+}$ , $Cu^{2+}$ , $Cr^{3+}$ )의 제거능 비교와 중금속 제거 전후의 crab shell의 표면 변화를 관찰해 보았다. Crab shell 충진 칼럼의 중금속 제거능을 알아보기 위해, 가장 변화가 많은 1,000 BVs까지의 crab shell g 당 각각 중금속의 제거량을 비교해 보면 $Pb^{2+}$(0.61 mmol/g) > $Cu^{2+}$(0.43 mmol/g) > $Cd^{2+}$(0.38 mmol/g) > $Cr^{3+}$(0.30 mmol/g) 순으로 나타났다. $Cd^{2+}$의 경우는 미세 침전보다는 내부의 화학적 침전이나 물리적 침전에 의한 제거가 더 많이 일어나고 $Pb^{2+}$의 경우는 유출되는 미세 침전량이 전체 제거량 중 26.6 %를 차지 하고 칼럼내 crab shell 표면에서도 다른 중금속들보다 월등히 많은 미세 침전물이 관찰 됨으로 $Pb^{2+}$의 경우는 중금속 제거는 화학적 침전이나 물리적 침전에 따른 미세침전에 의해 많이 이루어지고 있는 것으로 판단된다. $Cu^{2+}$와 $Cr^{3+}$의 경우, 중금속의 고유 색깔인 청색이 중금슥 제거가 끝난 후 crab shell 표면에 착색된 것을 관찰할 수 있었다. Crab shell 충진 칼럼을 이용한 수중 중금속 제거 후 중금속을 고농도로 수거하기 위한 탈착에 있어서는 초기 20 BVs 내에서 대부분의 중금속이 탈착되어 유출되는 것을 관찰 할 수 있었다.

• Journal of the Korean institute of surface engineering
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• v.44 no.5
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• pp.220-225
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• 2011

304 stainless steel plate was colored by hot dip and electrochemical treatment in a solution containing sulphuric and chromic acids. In the process, treatment variables such as operating time and methode were changed. The surface characteristics that changed by the treatment of the samples such as surface composition, oxide film thickness, color, surface roughness and reflectivity were studied. Surface composition was varied as follows. Fe was decreased, but Cr and O were increased. Ni was increased until 20 min, but reveals decreasing tendency as time passed after that. These means the surface film becomes chrome rich oxide phase as the treatment times increase. The thickness of film was about 220 nm at 30 min by dip treatment and it reduced as the treatment times increased. On the other hand, the thickness was about 150 nm at 10 min by electrochemical method and it doesn't increased with time. Surface color changed from metallic white of the base plate to gray, black, red, and green-blue, gradually, as the treating time increased. The reflectivity of colored surface measured by UVVIS-NIR spectrophotometer was reduced from max 38% of basis metal to min 3.5%.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.45-53
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• 2000

Enamel microabrasion is a means by which superficial enamel discoloration is removed using hydrochloric acid and fine pumice. As enamel microabrasion alone may not be sufficient in cases of deeper discoloration, composite resin restoration is recommended in areas where there is remaining discoloration. The purpose of this study was to investigate the effects of different methods and number of applications of enamel microabrasion on the shear bond strength of composite resin to enamel. Untreated control was designated as group 1. 5-second applications of a mixture of 18% HCl and fine pumice were performed 5 and 10 times on groups 2 and 3, respectively. A commercially available mixture of 10% HCl and abrasives(PREMA) was applied using a 10 : 1 gear reduction handpiece 5 and 10 times on groups 4 and 5, respectively, with each application lasting 20 seconds. After etching with 37% phosphoric acid, composite resin was bonded. Thermocycling was performed and shear bond strength was measured. The following results were obtained : 1. Group 2 showed the highest bond strength$(24.36{\pm}3.34)$, while group 3 showed the lowest$(19.35{\pm}3.43)$, Shear bond strength decreased in the following order: 2>4>5>1>3. 2. Group 2 showed bond strength significantly higher compared to groups 1 and 3(p<0.05). 3. There were no significant differences between groups 2 and 3, which had been microabraded using HCl and pumice, and groups 4 and 5, to which PREMA had been applied, when bond strengths were compared(p>0.05). 4. When modes of fracture were examined, adhesive failure was observed in groups 3 and 4, while cohesive failure was observed in groups 1, 2, 3 and 4. Only mixed failures were found group 5. 5. When viewed using a SEM, groups 2 and 3, which had been microabraded using HCl and pumice, showed surface appearances similar to that of enamel etched with phosphoric acid. Groups 4 and 5, treated with PREMA, exhibited a smooth surface similar to that of group 1. All oops showed similar, typical surface characteristics following phosphoric acid etching.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.126-133
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• 2019

In recent years, the deterioration of fruit quality caused by poor coloration and sunburn disorder has become serious problems in apple market, which is a result of the increase of surface temperature due to the abnormal temperature increase during summer season. This study was conducted to investigate the effect of wind net shading and fine water spray using sprinkler on fruit coloration, sunburn damage and overall fruit quality of 'Fuji' and 'Hongro' apples. Fifteen sprinklers (7L/hr) were installed at the orchard of the Chungcheongnam-do Agricultural Research and Extension Services, located in Sinam-myeon Chungcheongnam-do Korea, at a height of 3m above the apple tree of $1.5m{\times}3.5m$ north-south direction. Fine water spraying treatment was divided into day time spray (10:00 am to 6:00 pm) and all day spray (10:00 am to 10:00 pm) from early July to 10 days before harvest in 2017 and 2018 season, respectively. Temperature of the surface of apple fruit, characteristic of fruit, and degree of sunburn damage were investigated. In 'Fuji', the fruit surface temperature checked at 2 pm on August 10 was decreased considerably in the day time spray ($35.6^{\circ}C$) and wind net ($39.0^{\circ}C$) when compared with the untreated control ($44.4^{\circ}C$). Similarly, the fruit surface temperature also decreased considerably in the all day spray ($35.1^{\circ}C$) and wind net ($36.9^{\circ}C$) treatments when compared with the untreated control ($46.5^{\circ}C$) in 'Hongro' apples. The incidence of sunburn disorder was significantly decreased with day time spray (5.0%), all day spray (5.8%) and wind net (7.0%) when compared with untreated control (23.4%) in 'Fuji' apples. As a results, the treatment of fine water spray and wind net consequently showed 26% and 34% increase of redness ($a^*$) value in the skin color difference, respectively, in 'Fuji' apples.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.147-157
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• 2011

Purpose: The present study was conducted to investigate the actual condition of circle lens wear and the differences caused by the pigmentation in blinking rate, non-invasive tear break-up time (NIBUT), and lens surface between circle and soft contact lens wear during clinical application. Methods: Eighty subjects were surveyed to know the actual condition of wearing circle lens. Blink rate, NIBUT of 20 subjects in twenties were measured after separately wearing soft contact lens and circle lens for 5 days. Their lens surfaces were also observed by scanning electron microscope. Results: Fifty percent of circle lens wearers answered that major reason for changing circle lens was discomfort and 67% of answerers wore circle lens more than 6 hours a day. The tendency of increased blink rates in both wearers of circle and soft contact lens at 30 minutes later when tear film stabilized and 3 hour after lens wearing was shown on the 1st, 3rd and 5th day with expanding wearing time. Especially at 3 hours after lens wearing on the 3rd and 5th day, the difference of blink rates was statistically different in circle lens wear and soft contact lens wear. The NIBUTs of soft contact lens wearers and circle lens wearers were 6.0 and 3.7 secs, respectively, at 30 min later on 1st day and were significantly different. NIBUTs of soft contact lens wearers and circle lens wearers were also statistically different 3 hrs after lens wearing on the 1st day and the similar pattern of NIBUTs was shown on the 3rd and 5th day. The roughness of both surfaces in soft contact lens and front surface in circle lens was same. However, pigmented front surface of circle lens was rougher and uneven. Conclusions: As the results, the circle lens wearers might feel discomfort in clinical application since the difference in lens surface of circle lens would change lens wettability during wearing. The difference by tinting contact lens was shown from the result, which could help better wearing circle lens.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.61-64
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• 2007

Fe-PC와 Fe-TCPC를 합성하여 암모니아 탈착에 따른 촉매의 특성과 황화합물 및 아민류의 흡착실험을 수행하여 다음과 같은 결론을 얻었다. 1) FT-IR로 분석한 결과, Fe-TCPC는 Fe-PC에 비해 카르복실기의 특성 스펙트럼이 관찰되었고, SEM/EDS로 관찰한 결과 카르복실기의 영향으로 Fe의 비율이 낮고 산소의 량은 높게 나타났으므로 표면에 카르복실기가 존재하고 있음을 알 수 있었다. 2) TPD 실험에서 철 프탈로시아닌 유도체는 두 개의 피크가 저온부와 고온부에서 나타나 약산점과 강산점이 존재하고 있음을 확인 할 수 있었으며, 탈착량은 Fe-TCPC가 Fe-PC보다 고온부에서 강산량점량이 많았고 저온부에서 약산점량은 적게 나타난 것으로 보아 Fe-TCPC가 표면에 카르복실기의 화학적흡착 영향으로 강산점에서 많은 탈착이 일어났음을 의미한다. 3) Fe-TCPC는 Fe-PC보다 비표면적과 세공부피가 많았고, 과산화수소의 분해효율이 높아 촉매적 성질이 우수하였으며, 또한 입자의 크기도 작았음을 확인하였다. 이는 모든 조건에서 Fe-TCPC가 Fe-PC보다 흡착능력이 우수한 것으로 예측된다. 4)카르복실기가 치환된 철 프탈로시아닌 유도체의 제거효율은 아민화합물이 우수하지만 황화합물에서 다소 낮게 나타났다. 이 결과로 보아 아민류에 효과가 있는 카르복실 철 프탈로시아닌을 착색제로 사용하면 탈취 기능을 가진 안료가 될 것으로 생각된다.

• Journal of the Korean institute of surface engineering
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• v.52 no.1
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• pp.30-36
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• 2019

In this study, we investigated the effects of anodizing time, dyeing treatment time, and variations in coloring concentration on the color of an AA5052 alloy processed by dye-treated anodizing. The outward color of the anodized film changed to deep red according to increases in anodizing time, dyeing treatment time, and coloring concentration; accordingly, lightness $L^*$ decreased and saturation $a^*$ and $b^*$ increased. The concentration of the dye and the UV-visible absorbance showed a nearly perfect linear relationship, allowing a quantitative analysis of the absorbed dye. Because the quantity of absorbed dye increased as anodizing time, dyeing treatment time, and coloring concentration increased, the outward color of the anodized film deepened. In addition, from the GD-OES depth profile, we found that the dye was preferentially absorbed on the surface of the porous anodized film.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.239-239
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• 2015

삼성, LG전자 등 다양한 사업부의 White Anodizing구현기술의 Need는 항상 존재하고 있으며, 특히 White와 Black Color의 콤비네이션으로 친환경 이미지 강조 및 핸드폰의 고급화에 필연적인 메탈화로 작년부터 White Anodizing의 수요요청이 쇄도하고 있다. 그러나 현행 공업용 Anodizing 기술(황산법)은 봉공처리 전 착색공정에서 Red, Blue, Black 등 염료분자와 달리 염료 분자가 비교적 큰 White 염료는 Anodizing으로 성장된 다공성피막 내부로 들어가지 못해 국내 Anodizing전문기업 뿐만아니라 일본 기업 및 연구소 등에서도 무수한 시도를 하고 있지만 현재까지는 완벽한 White Anodizing구현기술이 전무한 상태이다. 이에 당사는 알루미늄합금을 White의 안료나 염료가 아닌 알칼리전해액의 Pulse전류인가 PEO(Plasma electrolytic oxidation)처리 공정에 의거 White Anodizing기술을 개발하고자 하였다. 알칼리 전해질에 의한 Anodizing 처리기술로 White와 유사한 색상을 구현하고 있으나, 수요자가 요구하는 White Anodizing으로 제품을 양산하는데 어려움이 있어 기존 Anodizing 처리 대신 Pulse전류인가 PEO처리기술로 White Color를 구현하여 수요요청이 쇄도한 국내외 기업체에 공급하고자 한다. 본 기술은 알카리 전해액을 사용하므로 친환경적이며, 다공성 피막으로 인한 우수한 도장 밀착성, 실링처리에 의한 내식성 향상, PEO 피막의 우수한 경도 및 내마모성 등을 나타내며, 알루미늄뿐만 아니라 마그네슘합금, 티타늄 등에도 공히 적용이 가능하며, White Anodizing의 특화된 기술로 표면처리기술 우위 선점 및 원가절감 등이 가능하다. 당사는 알루미늄 아노다이징 전문 기업으로서 내식성 목적의 연질 아노다이징 처리 및 고내마모성을 목적으로 하는 자동차 부품 및 기계 부품용 경질 아노다이징 처리를 주로 수행하고 있다. 본 발표에서는 당사의 표면처리 기술 및 알루미늄의 아노다이징에 대한 소개를 하고자 한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1407-1408
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• 2015

현재에는 과거와 달리 표면상 비춰지는 외모의 중요성이 강조되어 치아 교정을 해서 미적 욕구를 충족시키려는 사람들이 증가하고 있다. 특히나 치아를 교정할 때 사용되는 치아교정용 브라켓은 부착되는 위치가 치아 앞면이기 때문에 미관상의 중요성은 치아교정장치 중 가장 크다. 이러한 이유 때문에 미적인 부분을 고려하여 치아색과 유사한 브라켓이 개발되었는데, 이 브라켓은 레진 브라켓이다. 이는 치아 교정에 도움을 주면서 심미성이 우수한 장점이 있지만 음식을 섭취할 때 음식의 색소에 의해 브라켓의 색 변화가 일어난다는 단점이 있다. 본 연구에서는 사람들이 자주 섭취하는 음식이나 음료에 치아교정용 브라켓을 착색시켜 색이 변하는 정도의 차이를 컬러센서를 이용해 측정하였다. 이렇게 측정된 브라켓의 RGB 값은 객관적이고 정량적인 값을 나타낼 수 있다. 이는 브라켓의 변색 뿐만 아니라 치아 미백 치료에도 적용되어 사용될 수 있을 것이다.