• 대한치과보철학회지
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• 제36권4호
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• pp.549-565
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• 1998

Porcelain is considered to be one of the materials of choice for restoration where esthetics is of concern. But porcelain surface without final glazing treatment may induce undesirable results such as inflammatory response on adjacent soft tissues due to plaque accumulation and increased wear of opposing teeth. Therefore, rough porcelain surface must be smoothened by final glazing treatment or chairside polishing procedure. The purpose of this study was to compare the surface roughness among self-glazed, overglazed and polished porcelain with various polishing kit, and to detect which phase of polishing is optimal in clinic. Specimens were fabricated with Vita VMK porcelain. The surface treatment of each group was performed as follows. Group 1 : overglazing treatment Group 2 : self-glazing treatment Group 3 : polishing with the Truluster Polishing System for Porcelain(Brasseler, U.S.A.) Group 4 : polishing with the Exa Cerapol Adjustment kit (Edenta dental products, Switzerland) followed by finishing with diamond-filled polishing paste Group 5 : polishing with the Shofu Porcelain Adjustment kit (Shofu inc., Japan) followed by finishing with diamond-filled polishing paste. At each polishing steps, the measurement of Ra and Rq values were performed, and the surface was examined by scanning electron microscope. The results were as follows : 1. Overglazing treatment brought smoother surface than self-glazing treatment. 2. Polishing systems without porcelain polishing paste did not make better result than self-glazing treatment. 3. Polishing system with porcelain polishing paste made similar result to overglazing treatment. 4. Applying diamond-filled polishing paste after using polishing system which has no porcelain polishing paste produced surface as smooth as overglazing treatment does.

• 대한치과교정학회지
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• 제22권4호
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• pp.823-836
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• 1992

Guiding a tooth along an arch wire results in a counteracting frictional force among arch wires, bracket and ligature. This frictional forces should be eliminated or minimized when orthodontic teeth movement is being planned. The purpose of this study was to evaluate the changes of width, cross-sectional forms and surface morphologies of stainless steel wire and $Elgiloy^{\circledR}$ wire after electropolising. Experimental variables included in this experiment were arch wire materials, current, electrolyte temperature and polishing time. Wire widths were measured by micrometer and cross-sectional forms and surface morphologies were examined with optical microscope and scanning electron microcope. The results were as follows: 1. The mean and standard deviation of widths of stainless steel wire and $Elgiloy^{\circledR}$ wire varying polishing time with condition of $249A/dm^2$ and $20^{\circ}C,\;249A/dm^2$ and, $332A/dm^2$ and $20^{\circ}C$ and $332A/dm^2$ and $250^{\circ}C$ were obtained. 2. With increasing polishing time, the widths of stainless steel wire and $Elgiloy^{\circledR}$ wire became decreased proportionally 3. The changes of widths of stainless steel wire and $Elgiloy^{\circledR}$ wire were statistically insignificant between $20^{\circ}C$ group and $25^{\circ}C$ group, but significant between $249A/dm^2$ group and $332A/dm^2$ group. 4 The cross-sectional forms of wire after electropolishing were not changed in stainless steel wire, and while it were changed to rounded corners in $Elgiloy^{\circledR}$ wire. 5. The surface morphologies of wire after electropolishing were scratch-absent and more smoothened both in stainless steel wire and $Elgiloy^{\circledR}$ wire.

• 대한기계학회논문집A
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• 제27권3호
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• pp.335-342
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• 2003

In this study, the effects of oxide layer formed on the contact parts of TiN coated ball and steel disk in sliding are investigated. Also wear mechanism to from the oxide layer and the characteristics of the oxide layer formation are investigated. AISI 52100 steel ball is used for the substrate of coated ball specimens. Two types of coated ball specimens were prepared by depositing TiN coating with 1 and 4 ${\mu}{\textrm}{m}$ in coating thickness. AISI 1045 steel is used for the disk type counter-body. To investigate the effect of oxide layer on the contact parts of the two materials, the tests were performed both in air for forming oxide layer on the contact parts and in nitrogen environment to avoid oxidation. And to study the effects of surface roughness of counter-body, TiN coating thickness and contact load of sliding test on the characteristics of oxide layer formation on counter-body, various tests were carried out. From the results, the friction characteristics between the two materials was predominated by iron oxide layer that formed on wear track on counter-body and this layer caused the high friction. And the formation rate of the oxide layer on wear track increased as the real contact area between the two materials increased as the contact load increased, the TiN coating thickness decreased and the surface of counter-body smoothened.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.109-116
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• 2001

In this study, the effects of oxide layer formed on the contact parts of TiN coated ball and steel disk in sliding are investigated. Also wear mechanism to form the oxide layer and the characteristics of the oxide layer formation are investigated. AIS152100 steel ball is used for the substrate of coated ball specimens. Two types of coated ball specimens were prepared by depositing TiN coating with 1 and 4um in coating thickness. AISI1045 steel is used for the disk type counter-body. To investigate the effect of oxide layer on the contact parts of the two materials, the tests were performed both in ambient for forming oxide layer on the contact parts and in nitride environment to avoid oxidation. And to study the effects of surface roughness of counter-body, TiN coating thickness and contact load of sliding test on the characteristics of oxide layer formation on counter-body, various tests were carried out. From the results, the friction characteristics between the two materials was predominated by iron oxide layer that formed on wear track on counter-body and this layer caused the high friction. And the formation rate of the oxide layer on wear track increased as the real contact area between the two materials increased as the contact load increased, the TiN coating thickness decreased and the surface of counter-body smoothened.

• 구강생물연구
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• 제42권4호
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• pp.187-197
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• 2018

Chemical agents such as minocycline (MC) and citric acid (CA) were suggested in the treatment of contaminated implant surface. In this study, MC-HCl treatment was performed to enhance surface characteristics of titanium alloy surface. The purpose of this study was to assess the characteristics and the biocompatibility of Ti-6Al-4V surface treated by MC. Alpha-beta titanium alloy (Ti-6Al-4V) samples were prepared and they were divided into 6 groups according to chemical concentration and treatment time. These groups include 1) group I, non-treated smooth titanium alloy; 2) group II, MC 1.5 mg/mL for 1 hour; 3) group III, MC 1.5 mg/mL for 24 hours; 4) group IV, MC 15 mg/mL for 10 minutes; 5) group V, MC 100 mg/mL for 5 minutes; 6) group VI, pH1 CA for 3 minutes. The analysis of the surface characteristics of MC-treated titanium alloy was executed using scanning electron microscopy, roughness test, and X-ray photoelectron spectroscopy (XPS). Cell adhesion and MTT assay was done using MC3T3 cell. Titanium surfaces treated with MC indicated a more smoothened surface microstructure. For group II and III, the new peaks of rutile TiO2 were found. Group II and V have more basic group of Ti-OH form in XPS. In MTT assay, all MC-treated groups showed significantly higher cell viability compared to control. The surface roughness, crystal structure, surface hydrophilicity, cell viability of smooth titanium surface was improved by MC treatment. Compared with the control experiment and CA-treated group, smooth titanium surface treated with MC showed improved surface characteristics and cell biocompatibility.

• 대한의용생체공학회:의공학회지
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• 제24권2호
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• pp.77-82
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• 2003

삼차원 CT 영상을 이용하여 대장 내부의 병변을 관찰하고 진단하기 위한 비침습적 검사 방법인 가상 대장 내시경을 위하여 가상 카메라의 관찰점과 관찰 방향을 제공하기 위한 적절한 경로가 필요하다. 특히. 인간의 대장은 매우 길고 복잡하므로 사용자가 직접 경로를 생성하려면 많은 시간이 걸리고 정확한 결과를 기대하기 어렵다. 또한 경로를 자동으로 생성하는 기존의 방법들은 계산량이 많아 약 수 분에서 수 십분 이상의 수행 시간이 걸리고. 사람의 대장이 가지는 대표적인 구조인 두께가 급격히 변하거나 곡률이 큰 영역에서 적절한 중앙선을 얻기 어려우며. 끊김이 있는 부적절한 경로를 생성하고, 평활화된 경로가 대상체의 표면과 충돌할 가능성을 배제할 수 없다. 이 논문에서는 계산량이 적은 거리 지도 및 제안된 순서 지도를 이용하여 끊김이 없고 적절한 중앙선을 얻는 고속의 알고리즘을 제안한다 순서 지도는 대상체 내부의 각 복셀에서의 가능한 경로의 방향을 나타내며 거리 지도는 대상체 내부의 각 복셀과 가장 가까운 배경 복셀까지의 거리를 나타낸다. 제안한 방법에서는 두 지도들을 이용하여 끝점에서 출발하여 시작점을 향하는 동시에 더욱 넓은 영역으로 진행하는 경로를 얻으므로, 대상체의 두께와 곡률의 크기에 관계없이 적절한 중앙선을 얻을 수 있다. 이와 함께 경로의 충돌 가능성을 완전히 제거할 수 있는 간단한 평활화 방법을 제안한다 알고리즘의 적절성을 검증하기 위해 사람의 대장의 특징을 가진 팬텀(phantom) 데이터를 이용하여 실험하였다. 사람의 대장 CT 데이터를 이용하여 800MHz PC에서 1분 이내에 적절한 경로를 얻었으며 이를 따라 이동하는 가상의 카메라로부터 만족할만한 가상 대장 내시경 영상을 얻을 수 있음을 보였다.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제23권4호
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• pp.268-273
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• 2017

최근 감정 분류 분야에서 딥러닝 인코더 기반의 접근 방법이 활발히 적용되고 있다. 딥러닝 인코더 기반의 접근 방법은 가변 길이 문장을 고정 길이 문서 벡터로 압축하여 표현한다. 하지만 딥러닝 인코더에 흔히 사용되는 구조인 장 단기 기억망(Long Short-Term Memory network) 딥러닝 인코더는 문서가 길어지는 경우, 문서 벡터 표현의 품질이 저하된다고 알려져 있다. 본 논문에서는 효과적인 감정 문서의 분류를 위해, 장 단기 기억망의 출력을 중요도에 따라 가중합하여 문서 벡터 표현을 생성하는 주목방법 기반의 딥러닝 인코더를 사용하는 것을 제안한다. 또한, 주목 방법 기반의 딥러닝 인코더를 문서의 감정 분류 영역에 맞게 수정하는 방법을 제안한다. 제안하는 방법은 윈도우 주목 방법(Window Attention Method)을 적용한 단계와 주목 가중치 재조정(Weight Adjustment) 단계로 구성된다. 윈도우 주목 방법은 한 단어 이상으로 구성된 감정 자질을 효과적으로 인식하기 위해, 윈도우 단위로 가중치를 학습한다. 주목 가중치 재조정에서는 학습된 가중치를 평활화(Smoothing) 한다, 실험 결과, 본 논문에서 제안하는 방법은 정확도 기준으로 89.67%의 성능을 나타내어 장 단기 기억망 인코더보다 높은 성능을 보였다.

• 생명과학회지
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• 제30권11호
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• pp.973-982
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• 2020

본 연구는 지방구세포 감소를 위한 소재개발로 감국 추출물의 대표물질인 camphor가 갖는 지방구세포 분화억제효과를 관찰하였다. camphor의 세포독성을 확인하기 위해 3T3-L1 세포주를 이용하여 세포독성 측정을 1 day에서 10 day까지 확인하였고, 세포독성은 모두 없었다. PTCH siRNA를 처리 시 PTCH가 비활성되어 분화가 억제되었고, SMO siRNA 처리시 SMO가 비활성화되어 분화가 유도되었다. PTCH 억제는 SMO를 활성화시키는 기전으로HH 신호의 활성화가 지방구세포 분화를 억제시키는 것을 보여준다. FACS를 이용한 Gli1 발현은 KCTC 3237은 62.7±1.5%, camphor는 60.4±2.2% 로 분화된 세포 24.9±3.1% 보다 높은 것을 확인하였다. GC-MS에서 발효된 camphor의 구조변화는 없는 것으로 확인되었으나, KCTC 3237에서 15.41% 양적 증가를 확인했다. 또한camphor가 SMO를 과발현시키고, Gli1의 변화를 조절하였다. 따라서 감국 발효물의 생리활성 물질 중 향후 매커니즘 분석을 위한 활성물질인 camphor를 이용해 동물모델에서 비만억제 효과에 대한 자료가 더 필요할 것으로 여겨지며, 감국 추출물 및 발효물의 HH신호조절이 새로운 비만치료제로 개발될 수 있는 가능성을 제시하고자 한다.