• 대한치과의사협회지
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• 제48권9호
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• pp.680-687
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• 2010

The purpose of this study was to compare post cementation efficacy according to the different adhesive systems and cement delivery methods. A total of 40 extracted human single-rooted premolar teeth were randomly divided in four groups according to the two luting agents of Unicem applicap (3M ESPE, St. Paul, MN, USA) or Variolink II (Ivoclar Vivadent, Liechtenstein) and cement delivery methods of direct cement application or lentulo spiral application. After restoration using glass?fiber posts, the samples were embedded in acrylic resin. Three sections of 2 mm thickness were prepared from each specimen, and the post in each section was subjected to a push-out test. The data were analysed statistically at significant level of 95%. The Unicem had significantly higher push-out bond strength than Variolink and the lentulo spiral application made higher bond strength (p<0.05). Adhesive failure between cement and dentin was predominant in all groups. The Unicem of self-etch system and cement delivery using lentulo spiral showed clinically acceptable and comparable bonding strength for the fiber post.

• Restorative Dentistry and Endodontics
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• 제47권1호
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• pp.12.1-12.11
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• 2022

Objectives: This pilot study aimed to establish the interrelationship between collagen and mast cells in periapical granulomas and periapical cysts. Materials and Methods: An observational cross-sectional study was conducted on the paraffin-embedded tissue sections of 68 specimens (34 periapical granulomas and 34 periapical cysts). The specimens were stained with picrosirius to observe collagen fiber birefringence and anti-tryptase antibody to evaluate the mast cell count immunohistochemically. The mean number and birefringence of collagen fibers, as well as the mean number of mast cells (total, granulated, and degranulated), and the mean inflammatory cell density were calculated. The data obtained were analyzed using the Kruskal Wallis test, Mann Whitney U test, and Spearman correlation test (p < 0.05). Results: The mean number of thick collagen fibers was higher in periapical cysts, while that of thin fibers was higher in granulomas (p = 0.00). Cysts emitted orange-yellow to red birefringence, whereas periapical granulomas had predominantly green fibers (p = 0.00). The mean inflammatory cell density was comparable in all groups (p = 0.129). The number of total, degranulated, and granulated mast cells exhibited significant results (p = 0.00) in both groups. Thick cyst fibers showed significant inverse correlations with inflammation and degranulated mast cells (p = 0.041, 0.04 respectively). Conclusions: Mast cells and inflammatory cells influenced the nature of collagen fiber formation and its birefringence. This finding may assist in the prediction of the nature, pathogenesis, and biological behavior of periapical lesions.

• International Journal of Concrete Structures and Materials
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• 제3권1호
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• pp.71-77
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• 2009

A theoretical model of multiple cracking failure mechanism is proposed herein for fiber reinforced high performance Cementitious composites. By introducing partial debonding energy dissipation on non-first cracking plane and fiber reinforcing parameter, the failure mechanism model of multiple cracking is established based on the equilibrium assumption of total energy dissipation on the first crack plane and non-first cracking plane. Based on the assumption of the first crack to be the final failure crack, energy dissipation terms including complete debonding energy, partial debonding energy, strain energy of steel fiber, frictional energy, and matrix fracture energy have been modified and simplified. By comparing multiple cracking number and energy dissipations with experiment results of the reference's data, it indicates that this model can describe the multiple cracking behavior of fiber reinforced high performance cementitious composites and the influence of the partial debonding term on energy dissipation is significant. The model proposed may lay a foundation for the predictions of the first cracking capacity and post cracking capacity of fiber reinforced high performance cementitious composites and also can be a reference for optimal mixture for construction cost.

• 한국의류학회지
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• 제35권1호
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• pp.115-124
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• 2011

This study provides an eco-friendly dyeing processing for chitosan fiber using Oenothera odorata jacquin as a dye. The effects of chemical mordants (Al, Cu, Fe) and natural mordant (Chestnut shell) on the color change for dyed chitosan fibers were measured by K/S values, L, $a^*$, $b^*$, H, V, C values, color fastness, and antimicrobial activity. The results are as follows. Dyeing conditions of Oenothera odorata jacquin on chitosan fibers were optimized to $70^{\circ}C$, 30 minutes and 200% on weight of fabric (o.w.f.). The pre-mordant concentration of aluminium (Al), copper (Cu) and iron (Fe) of chitosan fibers was optimized to 3% (o.w.f.) and 1% (o.w.f.), respectively. The post-mordant concentration of chemicals, such as Al, Cu and Fe, on chitosan was determined to 1% (o.w.f.). The hue of chitosan fibers by chemical mordants was measured to be reddish & yellow. The pre-mordant concentration of Chestnut shell of chitosan was optimized to 70% (o.w.f.). The post-mordant concentration of Chestnut shell on chitosan was determined to be 50% (o.w.f.). The hue of chitosan fibers by Chestnut shell mordant was measured to be reddish & yellow. The wet cleaning fastness of chitosan fibers was improved by a pre-mordant that used chemical mordants. In the case of the Chestnut shell mordant, the wet cleaning fastness was improved by a post-mordant. The dry cleaning fastness of chitosan fibers was excellent regardless of mordants and mordant methods. The antimicrobial activity of the chitosan fiber was shown at 99.9% and its excellent qualities remained after the dyeing and mordant processing.

• 대한치과보철학회지
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• 제58권4호
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• pp.356-362
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• 2020

강동경희치대병원 보철과에서는 치료계획단계에서 마지막 결과를 미리 형상화하고 그것에 입각하여 치료를 진행하는 Top-Down 개념의 치료접근법을 2006년부터 실행하고 있다. 이번 증례도 그 개념에 입각하여 임플란트 수술에 앞서 미리 최종 보철치료의 방법과 결과를 형상화시켜 놓고 치료를 진행한 실례이다. 임플란트 보철의 여러 방법 중 시멘트 유지방식은 임플란트의 기울기에 구속받지 않고 간단하게 보철물 제작이 가능하나, 접착 후 치은 연하의 잉여 시멘트를 완전하게 제거하기 어렵고, 필요할 때 탈착이 불편하다는 단점이 있다. 따라서 전치부 임플란트 보철수복 시 SB-locking method의 유지방식을 이용하여 시멘트 유지방식의 문제를 해결하면서 심미적인 임플란트 보철수복이 가능했던 증례를 보고하고자 한다.

• 구강회복응용과학지
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• 제37권4호
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• pp.251-258
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• 2021

치아 외상은 어린이와 비교적 젊은 연령에서 흔히 발생하며 외상 발생 시점, 환자의 나이, 치아의 성숙 상태 등이 치료 방법에 영향을 미친다. 약 파절편이 건전하고 잔존 치아와 밀접한 적합을 보일 경우, 파절편 재부착은 유용한 치료 옵션이 될 수 있다. 이 방법은 치아 본래의 형태와 교합의 회복뿐만 아니라 기능, 표면 광택과 질감을 그대로 재현할 수 있는 여러 가지 이점이 있다. 본 증례보고는 복잡 치관 파절된 치아를 섬유 강화형 포스트를 활용하여 파절편 재부착을 시행한 두 증례에 대해 소개한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.99-104
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• 2000

In this paper, the crack properties fiber reinforced concrete(SFRC) beams by experimental method is discussed. The major role played by the steel fiber occurs in the post-cracking zone, in which the fibers bridge across the cracked matrix. Because of its improved ability to bridging cracks, SFRC has better crack properties than that of reinforced concrete(RC). Crack properties are influenced by longitudinal reinforcement ratio, volume and type of steel fibers, strength of concrete and the stress level. Crack width and number of cracks in SFRC beams have been evaluated from experimental test data at various levels of stress for the tested beams.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.635-638
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• 2000

This experimental were carried out in order to investigate the equivalent strength of SFRC (Steel Fiber Reinforced Concrete). Tow hundred and tenh SFRC beeam (size: 150x150x550) were used in the tests the relationships between loading and mid-point deflections of the beams were observed four oint bending loading. From the test results, prediction formulas for the equivalent strength of SFRC beams are suggested.

• Structural Engineering and Mechanics
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• 제22권3호
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• pp.311-330
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• 2006

Standard compression tests of steel fiber reinforced concrete (SFRC) cylinders are conducted to formulate compressive stress versus compressive strain relationship of SFRC. Axial pullout tests of SFRC specimens are also conducted to explore its tensile stress strain relationship. Cover concrete spalling and reinforcement buckling models developed originally for normal reinforced concrete are modified to extend their application to SFRC. Thus obtained monotonic material models of concrete and reinforcing bars in SFRC members are combined with unloading/reloading loops used in the cyclic models of concrete and reinforcing bars in normal reinforced concrete. The resulting path-dependent cyclic material models are then incorporated in a finite-element based fiber analysis program. The applicability of these models at member level is verified by simulating cyclic lateral loading tests of SFRC columns under constant axial compression. The analysis using the proposed SFRC models yield results that are much closer to the experimental results than the analytical results obtained using the normal reinforced concrete models are.

• 펄프종이기술
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• 제36권1호
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• pp.61-66
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• 2004

Bleached chemithermomechanical pulp (BCTMP) was produced from CTMP of Betula maximowicziana Regel by two staged ozone-hydrogen peroxide bleaching in order to improve the optical properties of high yield pulp. This pulp was used for the evaluation of optical properties improvement, chemical characteristics of lignin in fiber and the relationship between lignin and optical properties in fiber cell wall. Hydrogen peroxide treatment improved the brightness, but the post color number (PC No.). There was little improvement on optical properties by ozone treatment, but this could be improved more by using two staged ozone-hydrogen peroxide bleaching. The hydrogen peroxide treatment did not make any change on chemical characteristics of lignin in cell wall, but by ozone treatment, it was found that the non-aromatic conjugated structure was existed in the surface of cell wall, but this could be removed by hydrogen peroxide treatment in two staged ozone-hydrogen peroxide treatment. Therefore, the optical properties was significantly improved, due to the removal of non-aromatic conjugated structure.