• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.802-811
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• 1995

The purpose of this in vitro study was to compare the bleaching effect and the surface change according to three bleaching agents (Rembrandt, Natural White, Hi-Lite). Teeth were stained by artificial food colorants for 6 weeks and bleached for 4 weeks. The teeth were evaluated with spectrophotometer after bleaching on the 1st week and on the 4th week. The surface change of enamel was evaluated under SEM after exposure to 3 agents for 1 and 24 hours. The results were as follows : 1. All groups showed increased Lightness difference after bleaching. 2. After 1 week, only Rembrandt group showed significant bleaching effect compared to control group. 3. After 4 weeks, Rembrandt group and Hi-Lite group showed significant bleaching effect compared to control group. 4. SEM evaluation revealed that enamel surface underwent considerable change after 24 hours. Scratch disappeared and smooth surface was shown.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.210-216
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• 2002

Air abrasion technology can prepare enamel and dentin for bonding, similar to etching by acidic gels and solutions. Longer treatment can excavate pit and fissures, preparing the tooth for immediate placement of bonded resin materials. Although not appropriate for every clinical situation, the air abrasive technology minimizes heat, vibration and bone-conducted noise associated with conventional means of caries removal since the cutting is accomplished by air pressure. Also, patients treated with the air-abrasion technology rarely request anesthesia. Air abrasion technology was more effective in treating early carious lesions and stains compared to lesions where caries had already progressed to produce soft dentin and the strong air stream and noise caused by the evacuation system was a major discomfort to pediatric patients, and the experience and skillfulness of clinician should be required for accurate and proper tooth preparation.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.295-303
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• 2014

Purpose: This study aims to observe bleaching resulted from multipurpose contact lens solutions used to manage lenses with the subjects of colored contact lenses being distributed in Korea. Methods: The lenses have been worn for six months, and their refraction is 0.00D. Three types of colored contact lenses of which margin has been colored with a different manufacturing method have been adopted (type 1: pigment application method, type 2: chemical bonding process, type 3: sandwich method), and multipurpose solutions used were two types containing different components. Each of the colored contact lenses was stored in the multipurpose solutions for 20 days and went through vortexing for 15 seconds per day. Their fluorescence absorbance, surface roughness, brightness index, and color coordinate index were measured before and after the vortexing to see the degree of bleaching. Results: In the two types of multipurpose solutions, every type of the color contact lenses showed no statistically significant difference in their fluorescence absorbance value before and after the vortexing. Regarding surface image, the front surface of the lenses was smooth in every type, and about the back surface, type 3 indicated less protrusion than type 1 and 2. About the difference of color on the lens surface before and after the vortexing, type 3 showed significantly less difference than type 1 and 2; however, all fell into the permissible error. Conclusions: About the bleaching of colored contact lenses resulted from multipurpose solutions for soft contact lenses, there was no difference observed in terms of fluorescence absorbance and color. According to the methods of manufacturing dyes, however, there was difference in the protrusion of the posterior surface image.

• Journal of the Korean Wood Science and Technology
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• v.35 no.3
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• pp.70-78
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• 2007

This study explored the efficient dyeing method of aged chestnut wood using the natural dyes extracted from Gardenia jasminoides for, grandiflora, Carthamus tinctorius L., Rhus javanica L., Lithospermum erythrorhizon S. et Z., Caesalpinia sappan L. and Castanea crenata S. et Z.. The color variation of the dyed chestnut woods was also quantitatively evaluated. The wood specimens revealed abundant colors through different dyeing conditions such as dyeing temperature, dye pH, soaking time, and brushing frequency. The chroma and stain concentration of colored woods were calculated with $L^*$, $a^*$ and $b^*$ in order to make color tone measurement. Brushing treatment for colored wood was confirmed as a more economical dyeing method than soaking treatment requiring more time when natural dyeing was done. Furthermore, the desirable tone and shade of color was easily obtained by repetitive brushing treatment using low color tone. During natural dyeing, good color expression was made with high temperature and acidic condition of a dyeing liquor.

• Journal of dental hygiene science
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• v.13 no.2
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• pp.203-212
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• 2013

The tooth morphology and qualitative mineral contents on enamel surface using energy dispersive X-ray spectroscopy, (EDX) were examined in the white-toothed shrew (genus Crocidura ) Crocidura lasiura and C. suaveolens and the red-toothed shrew (genus Sorex) Sorex caecutiens. In the case of C. lasiura and C. suaveolens, dental formula was found I 3/1 C1/1 P1/1 M3/3=28. The upper 1st and 2nd molars had an unequal W-shape formed by 5 cusps on the crown. The 3rd molar was found one-third the size of those of 1st and 2nd molars. The upper 1st incisor had two different sized hook-shapes and the lower 1st incisor was even. In the case of S. caecutiens, dental formula was found to be I3/1 C1/1 P3/1 M3/3=32. The upper 1st and 2nd molars had an equal W-shape on crown. The upper 3rd molar was half the size of those of the other molars. The upper 1st incisor possessed two similar sized hook-shapes and the lower 1st incisor had an uneven and serrated form. A comparison with the dental and cranial measurements revealed C. lasiura to be the largest of the three species (p<0.001) and C. suaveolens and S. caecutiens were similar in size (p>0.05). A qualitative analysis of mineral contents on enamel surface of the lower 1st incisor and lower 1st molar using EDX revealed C, O, P, Ca and Cu in all specimens and Pb was detected in several enamel specimens. No significant differences in the mineral contents (% weight) were observed among the three species (p>0.05). Fe was only detected on enamel surface of S. caecutiens with red pigmented teeth. Therefore, Fe is responsible for the red tip of the teeth. These results suggest that tooth morphological characteristics including the color of the tooth tip might be used as the key classifying species belonging to Crocidura and Sorex.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.675-687
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• 2005

The rocks of the five storied stone pagoda in the Jeongrimsaji temple site are 149 materials in total with porphyritic biotite granodiorite. They include pegmatite veinlet, basic xenolith and evenly developed plagioclase porphyry. This stone pagoda has comparably small fracture and cracks which are farmed in the times of rock properties, but surface exfoliation and granular decomposition are in process actively since the rocks are generally weakened from the influence of air contaminants and acid rain. Structural instability of constituting rocks in the 4th roof materials are observed to occur from distortion and tilt. Such instability is judged to threat stability of the upper part of the stone pagoda. Also, chemical weathering is operating even more as the contaminants, ferro-manganese hydroxides eluted from water-rock interaction on the rock surface. Most of the rock surface is covered with yellowish brown, dark black and light gray contaminants, and especially occur in the lower part of the roof rocks on each floor. The roof underpinning rocks are severe in surface pigmentation from manganese hydroxides and light gray contaminants. The surface of rocks lives bacteria. algae, lichen, or moss and diverse productions in colors of light gray, dark Bray and dark green. Grayish white crustose lichen grows thick on the surface with darkly discolored by fungi and algae in the first stage on basement rocks, and weeds grows wild on the upper part of each roof rocks. This stone pagoda must closely observe the movements of the upper part rock materials through minute safety diagnosis and long term monitoring for structural stability. Especially since the surface discoloration of rocks and pigmentation of secondary contaminants are severe, establishment of general restoration and scientific conservation treatment are necessary through more detailed study for this stone pagoda.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.105-115
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• 2008

Statement of problem: Proper finishing and polishing enhance both the esthetics and the longevity of restored teeth. Blade finishing technique would be suited for smoothing and finishing. Evaluation of this technique are necessary. Purpose: The purpose of this study was to evaluate the blade finishing and polishing procedures on the surface profile and roughness of ormocer-based composite resin and nanohybrid composite resin. Material and methods: The material included a ormocer-based composite resin ($Admira^{(R)}$ & $Admira^{(R)}$ Flow); a nanohybrid composite resin ($Grandio^{(R)}$ & $Grandio^{(R)}$ Flow). One hundred forty specimens of each group were prepared using a mylar strip and randomly divied into blade finishing and rubber polishing groups (n=10). The average surface roughness (Ra) in micrometers was measured and the surface profile was examined by scanning electron microscopy (SEM) (Magnification ${\times}$ 200). The data were analyzed by Mann-Whitney Test at 0.05 significance level. Conclusion: The results of this study indicated that the mylar strip produced the smoothest surface on all materials and among the finishing-polishing methods was not significanct difference (P>0.05). Ormocer-based flowable composite resin performedthe lowest variability in initial surface roughness among the tested materials.

• Journal of Pharmacopuncture
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• v.11 no.1
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• pp.13-19
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• 2008

Objectives : Demonstrating a novel circulatory path from the acupoint(CV12) to the pancreas. Method : Alcian blue(1% solution, $20{\mu}l$, pH 7.4) was injected into the acupoint(CV12). Two hours later the surfaces of internal organs were observed by using a stereomicroscope. Results : Alcian blue arrived and colored the omental fat band(OFB) on the pancreas. The OFB connected the head and tail of the pancreas, the pancreas and the spleen, and the pancreas and the stomach. Conclusion : The existence of a novel circulatory path from the acupoint CV12 to the pancreas and its OFB was demonstrated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.97-102
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• 2004

용액 중에서 나노입자의 전기영동 특성을 이용한 전자종이용 잉크 제조를 위해 $TiO_2$ 나노입자를 저유전율 용매인 cyclohexane에 혼합한 후 용매와 용질의 비중차를 줄이기 위해 분말 상 polyethylen을 첨가하여 high energy milling의 방법으로 입자분쇄와 동시에 입자 표면에 고분자 풍을 코팅하였다. 용액내의 입자 분산성 향상과 용매 착색을 위하여 계면활성제와 oil-blue N을 첨가한 후 전자종이용 잉크를 제조하여 측정한 제타 전위 결과 cyclohexane 내에서 $TiO_2$의 제타전위는 -40mV 정도였으나 polyethylene으로 코팅한 후 계면활성제를 첨가하였을 경우 최대 -110mV 이상의 높은 값을 나타내었다. 실제 디스플레이 특성을 평가하기 위해 포토리소그래피를 이용하여 3인치 크기의 ITO glass 위에 $10{\mu}m$의 크기를 갖는 십자형의 격벽을 $40{\mu}m$의 높이로 균일하게 형성한 후 합성된 전자잉크로 주입하여 상부전극과 하부전극사이에 UV 경화제를 도포하여 UV 접합을 실시하였다. 격벽 내에서 입자의 mobility를 측정하여 환산된 전자잉크의 응답속도는 0.1cm/sec로 측정되었으나, 전기영동시 입자들의 움직임에 따른 반사광의 파형을 측정한 경우 0.07cm/sec의 응답속도를 나타내었다.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.20-20
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• 2009

저항 점 용접은 1930년대에 Thomson에 의해 방법이 제안된 이후로 자동차, 전자, 항공기, 철도산업등에서 박판 금속(sheet metal)의 접합에 가장 널리 사용되고 있는 공정이다. 특히 자동차 차체와 같이 대부분 박판으로 구성되는 구조물에서는 저항 점 용접의 사용 범위가 매우 넓기 때문에 자동차 산업에서는 가장 기본적인 근본 기술 중의 하나로 인식되고 있다. 보통 자동차 한대를 생산하는데 소요되는 저항 점 용접 타점은 3000~4000개 정도로 자동차 차체 용접 공정의 대부분을 차지하고 있다. 또한 로봇과 연동된 자동화 공정으로 적용되고 있다. 최근의 자동차 차체를 구성하는 금속 재료가 자동차의 경량화, 친화경 소재의 사용자의 요구로 인해 새로운 강판이 사용된다. 자동차의 연비 향상을 위해서 다른 방법보다 자동차의 무게를 감소시키는 것이 가장 효율적이고, 쉽기 때문에 고장력 강판의 사용이 급속하게 증가하고 있다. 뿐만 아니라 차제의 부식성, 내마모성 향상을 위해 도금 처리된 강판의 사용도 활발하게 이루어지고 있다. 최근에 도장 공정 감소를 위해 도금 처리위에 도료 착색을 용이하게 하는 도료의 일부를 금속 표면에 처리된 강판의 개발도 진행되는 등 금속 소재의 변화가 다양하게 진행되고 있다. 이러한 새로운 강종은 기존의 AC 용접이나 DC 용접으로는 용접성 확보에 어려움을 가지고 있어, 새로운 저항 점 용접 공정의 연구 개발이 필요하다. 본 연구에서는 저항 점 용접 공정의 개선을 위해서 인버터 저항 점 용접기에서 용접 공정 중 전류를 제어하기 위한 효율적인 제어기 개발 방법과 개발된 제어기를 바탕으로 용접 중에 용접부의 품질을 예측하여, 용접 전류 및 가압력을 실시간 제어하여 안정적인 용접부의 품질을 갖질 수 있는 지능형 저항 점 용접기의 적응 제어기를 개발하는데 있다.