• 대한관절경학회지
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• 제11권1호
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• pp.24-31
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• 2007

목적: 견관절 유착성 관절 낭염으로 진단된 환자들에서 회전근 개 병변의 동반 정도를 자기 공명 관절 조영술(magnetic resonance arthrography, MRA) 및 초음파 (ultrasonography, USG)를 이용해 평가해 보았으며, 검사 소견에 있어서 MRA 및 USG의 차이점을 알아보았다. 대상 및 방법: 2005년 6월부터 12월까지 견관절 유착성 관절 낭염으로 진단한 연속된 80명의 환자를 대상으로 전향적 연구를 시행하였다. 무작위로 나누어 MRA 혹은 USG를 시행하였으며, 견관절 유착성 관절 낭염 환자에서 극상근을 중심으로 한 회전근 개 병변의 동반 정도를 조사하였다. 결과: 여섯 예(MRA 4, USG 2, 8%)에서 극상근에 소규모(1cm 이하)의 전층 파열을 보였으며 극상근의 부분 파열은 21예(MRA 12, USG 9, 26%)에서 관찰되었다. 뿐만 아니라 극상근의 건 병증(tendinopathy)이 15예(MRA 7, USG 8, 19%)에서 관찰되어, 총 42예(53%)에서 극상근 병변을 동반하고 있었다(MRA 23, 68% USG 19, 41%). 견갑하근의 부분 파열을 동반한 경우는 9예(MRA 6, USG 3, 11%)로 관찰되었다. 두 군간 극상근 병변의 동반 정도에 유의한 차이는 없었다(p>0.5). 결론: 견관절 유착성 관절 낭염 환자들을 대상으로 하여 시행한 MRA 또는 USG검사 상, 약 반 수(53%)의 환자들에서 극상근의 병변이 동반된 소견을 보였다. 유의한 차이는 없었으나, USG군 보다 MRA군에서 다소 높은 회전근 개 병변의 동반소견을 보였으며 이는 MRA가 USG보다 해상도가 더 뛰어 난 데서 기인한 것으로 생각된다.

• Journal of Korean Dental Science
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• 제8권2호
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• pp.49-56
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• 2015

Purpose: The effect of accelerated aging on color stability of various dual-cured self-adhesive resin cements were evaluated in this study. Materials and Methods: Color stability was examined using three different brands of dual-cured self-adhesive resin cements: G-CEM LinkAce (GC America), MaxCem Elite (Kerr), and PermaCem 2.0 (DMG) with the equivalent color shade. Each resin cement was filled with Teflon mold which has 6 mm diameter and 2 mm thickness. Each specimen was light cured for 20 seconds using light emitting diode (LED) light curing unit. In order to evaluate the effect of accelerated aging on color stability, color parameters (Commission Internationale de l'Eclairage, CIE $L^*$, $a^*$, $b^*$) and color differences (${\Delta}E^*$) were measured at three times: immediately, after 24 hours, and after thermocycling. The $L^*$, $a^*$, $b^*$ values were analyzed using Friedman test and ${\Delta}E^*$ values on the effect of 24 hours and accelerated aging were analyzed using t-test. These values were compared with the limit value of color difference (${\Delta}E^*=3.7$) for dental restoration. One-way ANOVA and Scheff's test (P<0.05) were performed to analyze each ${\Delta}E^*$ values between cements at each test period. Result: There was statistically significant difference in comparison of color specification ($L^*$, $a^*$, $b^*$) values after accelerated aging except $L^*$ value of G-CEM LinkAce (P<0.05). After 24 hours, color difference (${\Delta}E^*$) values were ranged from 2.47 to 3.48 and $L^*$ values decreased and $b^*$ values increased in all types of cement and MaxCem Elite had high color stability (P<0.05). After thermocycling, color change's tendency of cement was varied and color difference (${\Delta}E^*$) values were ranged from 0.82 to 2.87 and G-CEM LinkAce had high color stability (P<0.05). Conclusion: Color stability of dual-cured self-adhesive resin cements after accelerated aging was evaluated and statistically significant color changes occurred within clinically acceptable range.

• Restorative Dentistry and Endodontics
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• 제28권1호
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• pp.23-33
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• 2003

The purpose of this study was to compare in vitro interfacial relationship of restorations bonded with three self-etching primer adhesives and one self-etching adhesive. Class I cavity preparations were prepared on twenty extracted human molars. Prepared teeth were divided into four groups and restored with four adhesives and composites Clearfil SE $Bond/Clearfil^{TM}$ AP-X (SE), UniFil $Bond/UniFil^{\circledR}$ F (UF), FL $Bond/Filtek^{TM}$ Z 250 (FL) and Prompt $L-Pop/Filtek^{TM}$ Z 250 (LP) After storing in distilled water of room temperature for 24 hours, the specimens were vertically sectioned and decalcified. Morphological patterns between the enamel/dentin and adhesives were observed under SEM. The results of this study were as follows : 1. They showed close adaptation between enamel and SE, UF and FL except for LP. 2. The hybrid layer in dentin was $2{\;}\mu\textrm{m}$ thick in SE, $1.5{\;}\mu\textrm{m}$ thick in UF, and $0.4{\;}\mu\textrm{m}$ in both FL and LP. So, the hybrid layers of SE and UF were slightly thicker than that of FL and LP. 3. The lengths and diameters of resin tags in UF and FL were similar, but those of LP were slightly shorter and slenderer than those of SE. 4. The resin tags were long rod shape in SE, and funnel shape in other groups Within the limitations of this study, it was concluded that self-etching primer adhesives showed close adaptation on enamel. In addition, the thickness of hybrid layer ranged from $0.4-1.5{\;}\mu\textrm{m}$ between adhesives and dentin. The resin tags were long rod or funnel shape, and dimension of them was similar or different among adhesives.

• 접착 및 계면
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• 제16권2호
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• pp.69-75
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• 2015

돌침대에 사용되는 석재의 무게를 줄여 경량화를 추구하려면 석재의 두께를 줄이고 보강재료로 석재의 강도를 유지해야 한다. 본 연구에서는 돌침대용 석재/목재 보드 개발에 대한 연구를 진행하였다. 돌침대에 삽입될 돌의 무게를 줄이기 위해 석재와 목재를 접합하였다. 목재의 강도 향상과 표면개질을 위하여 열처리 조건에 따른 목재의 물성변화를 관찰하였다. 대기 조건에서 열처리한 목재의 경우 고온의 온도에 따라 목재의 강성이 높아졌다. 열처리 최적조건은 표면에너지와 인장, 굴곡 강도변화 경향을 바탕으로 $100^{\circ}C$ 조건임을 확인하였다. 석재와 목재간 높은 접착력을 확보하기 위해 최적의 접착제 조성을 연구하였다. 아민계 에폭시 접착제, 폴리우레탄(PU)계 접착제, 염화고무계(CR) 접착제 마지막으로 염화비닐초산계 접착제에 따른 석재와 목재간 랩 전단실험을 진행하였다. 랩 전단 실험 후 파단면을 관찰해볼 때 에폭시 접착제를 이용할 때 목재 기지의 인열 파괴가 발생되었다. 접착면에서의 전단력이 목재 자체의 파괴 강도보다 높다는 결과를 바탕으로 최적의 접착제 조건이 에폭시계 접착제임을 확인할 수 있었다.

• 한국재료학회지
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• 제8권8호
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• pp.744-750
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• 1998

마이크로 머신 소자는 일반전자 소자와 달리 소자 자체에 미세한 기계적 구조물을 갖고 있으며, 이의 구동을 통하여 센서 또는 엑츄에이터의 기능을 갖게 된다. 이 소자들은 그 작동 요구특성에 따라 패키지의 기계적, 환경적 격리를 요구하거나 분위기조절이 요구되는 등 까다로운 패키지 특성을 필요로 한다. 또한 미세한 작동소자들로 인하여 열 및 열응력에 매우 민감하며, 패키지방법에 따라 구동부위의 작동 특성이 크게 변화할 수 있다. 본 연구에서는 마이크로 머신 소자가 패키지 상에 접촉되어 패키지 될 때, 소자의 접촉 재료 및 공정온도, 크기 등이 마이크로 머신 소자에 미치는 열응력을 연구하였다. 유한요소해석법을 사용하여 소자에 미치는 열응력과 이로 인한 마이크로머신 소자의 물리적 변형을 예측하고, 이를 통하여 마이크로 머신 소자 패키지에 최소한의 열응력을 미치는 소자접속 재료의 선별과 패키지 설계의 최적화를 이루고자 하였다.

• 한국의류학회지
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• 제34권1호
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• pp.167-174
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• 2010

This paper aims to examine the status of sizing specifications for disposable sanitary pads on the market and to offer information on product design that reflect the requests of consumer by gathering opinion through the practical experience of consumers. Seventy-six varieties of sanitary pads on market are measured and the evaluations of wearing comfort were investigated by the questionnaire and interview for sixty three varieties of sanitary pads. As a result, they were classified into five sizes related with length but vaguely related with thickness and width. Thickness is distinguished by the compressibility that is marked as slim or ultra slim by the same brand. However, there is no sizing consistency for all products. The result shows that there is some confusion for consumers to choose desired sizes, In addition, the perception of wearing is categorized into four factors that are product performance, size and fit, wearing feeling and margin of action, and adhesive property and wrapping. The manufacturing specifications for the sanitary pads on domestic market, the requests of consumers for sanitary pad design modifications, and proposals for follow-up studies were figured out through this research.

• 한국해양공학회지
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• 제23권6호
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• pp.124-130
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• 2009

This study presents a finite element simulation of elastic waves for detecting anti-symmetric damages in an adhesively-bonded single lap joint. Plane strain elements were used for modeling adherents (aluminum) and adhesives (epoxy). Three types of damage were introduced: thickness reduction, elasticity deterioration, and voids in the adhesive layers, and two excitation and reception arrangements (ER1 and ER2) were used to investigate the detectability of the damage. The simulation showed that symmetrically located damage, such as a thickness reduction, can be detected by one excitation and one reception arrangement (ER1) and anti-symmetric damages, such as elasticity deterioration and voids, can be detected by modified two-point elastic wave excitation (ER2). Compared with the ER1 arrangement, the ER2 arrangement does not require a baseline signal for damage detection; hence, an efficient method of anti-symmetric damage detection in an adhesively-bonded single lap joint is proposed.

• Structural Engineering and Mechanics
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• 제68권2호
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• pp.171-182
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• 2018

For the first time, nonlocal damped vibration and buckling analyses of arbitrary tapered bidirectional functionally graded solid circular nano-plate (BDFGSCNP) are presented by employing modified spectral Ritz method. The energy method based on Love-Kirchhoff plate theory assumptions is applied to derive neutral equilibrium equation. The Eringen's nonlocal continuum theory is taken into account to capture small-scale effects. The characteristic equations and corresponding first mode shapes are calculated by using a novel modified basis in spectral Ritz method. The modified basis is in terms of orthogonal shifted Chebyshev polynomials of the first kind to avoid employing adhesive functions in the spectral Ritz method. The fast convergence and compatibility with various conditions are advantages of the modified spectral Ritz method. A more accurate multivariable function is used to model two-directional variations of elasticity modulus and mass density. The effects of nanoscale, in-plane pre-load, distributed dashpot, arbitrary tapering, pinned and clamped boundary conditions on natural frequencies and buckling loads are investigated. Observing an excellent agreement between results of current work and outcomes of previously published works in literature, indicates the results' accuracy in current work.

• 한국생산제조학회지
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• 제23권4호
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• pp.398-402
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• 2014

This paper presents the results of a study on the optimal footpad design for vertical climbing on acrylic surfaces with various curvatures used Taguchi methods. For a climbing robot, the adhesion system plays an important role in the climbing process. Only an appropriate adhesion strength will prevent the robot from falling and allow it to climb normally. Therefore, the footpad is a significant parameter for a climbing robot and should be studied. Taguchi methods were used to obtain a robust optimal design, where the design variables were the flat tacky elastomeric shape, area, thickness, and foam thickness of the footpad. Experiments were conducted using acrylic surfaces with various curvatures. An optimized footpad was selected based on the results of the experiments and analysis, and the stability of the wall-climbing robot was verified.

• 센서학회지
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• 제9권4호
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• pp.327-333
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• 2000

중심주파수가 340MHz이고 $1.435{\mu}m$의 IDT 전극 폭과 간격을 가진 양방향 전송형 SAW필터를 LN $128^{\circ}$ Y-X 웨이퍼의 압전기판으로 제작하였다. 전력 내구성을 개선시키기 위한 방안으로 Al에 비해 밀도가 크고, 열팽창계수가 작으며 접착력이 좋은 Ti를 압전체기판과 전극물질인 Al 사이에 증착시켰다. Ti의 두께 및 열처리 온도가 내전력 특성에 미치는 영향을 분석하였는데, Ti층이 두꺼울수록 내전력이 개선되었으며, 특히 $300^{\circ}C$에서 열처리하였을 때 가장 우수하였다.