• 대한치과보철학회:학술대회논문집
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• 2005.11a
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• pp.70-70
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• 2005

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.206-214
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• 2009

Statement of problem: There are common clinical cases in which the mandibular first and second molars are missing unilaterally. Purpose: This study was designed to compare and evaluate the magnitude and distribution of stress produced by four kinds of mandibular unilateral free-end removable partial dentures that could be applied clinically in Kennedy class II cases. Material and methods: Four unilateral free-end removable partial dentures using clasp, Konus crown, resilient attachment, and flexible resin were fabricated on the photoelastic models of the Kennedy class II cases. The vertical load of 6㎏ was applied on the central fossa of the first molar of every removable partial denture in the stress freezing furnace and the photoelastic models were frozen according to the stress freezing cycle. After these models were sliced mesio-distally to a thickness of 6mm, the photoelastic isochromatic white and black lines of the sliced specimens were examined with the transparent photoelastic experiment device and photographs were taken with a digital camera. The fringe order numbers at eight measuring points in the photograph were measured with the naked eye. Results: The maximum fringe order number of each sliced specimen and the fringe order number at the residual ridge just below the loading point were in the decreasing order of the unilateral removable partial dentures using flexible resin followed by clasp, resilient attachment, and Konus crown. The fringe order number at the root apex of the second premolar was in the decreasing order of the unilateral removable partial dentures using clasp followed by flexible resin, Konus crown, and resilient attachment. Conclusion: The removable partial denture using Konus crown showed the most equalized stress distribution to the supporting alveolar bone of abutment teeth and residual ridge under the vertical loads. The removable partial denture using flexible resin can be applied to the case that has a better state of residual ridge than abutment teeth.

• 대한치과보철학회:학술대회논문집
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• 1998.11a
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• pp.52-52
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• 1998

• 대한치과보철학회:학술대회논문집
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• 1996.11a
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• pp.104-105
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• 1996

• The Journal of the Korean dental association
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• v.23 no.1 s.188
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• pp.45-60
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• 1985

• The Journal of the Korean dental association
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• v.35 no.4 s.335
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• pp.251-265
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• 1997

• The Journal of the Korean dental association
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• v.27 no.2 s.237
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• pp.161-169
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• 1989

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.4
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• pp.611-621
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• 1992

The Present study was performed to evaluate the stress distribution patterns of bone tissues around two Branemark implant fixtures with varying lengths. Six models were used with the combination of 10mm, 7mm, 5mm Branemark implant fixture analogs. The load distribution characteristics of surrounding bone tissues were observed under 64kg vertical static loading on central part of fixed bridge using 2 dimensional photoelastic technique. Through observing the pattern of stress distribution around the implant fixtures, I got the results as follow : 1. Stress distribution pattern of model I(10mm, 10mm) was best among those of six models. 2. When two fixtures were in equal length, stress was increased in proportion to the reduction of implant surface area. 3. When two fixtures were in unequal length, stress was concentrated on the neck portion of the shorter one.

• ETRI Journal
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• v.14 no.1
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• pp.108-117
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• 1992

광통신 시스팀에서 신호접속용으로 사용되는 광커넥터의 결합기구 중 세라믹 페룰-슬리브의 정렬기구에서 발생하는 성능저하 현상을 다루었다. 성능저하 현상으로 페룰 단면연마시 발생하는 Vertex Eccentricty, 좌굴현상, 환경에 따른 탄성 및 응력의 변화, 마모, 피로파괴 등에 대한 이론적인 배경과 실험결과를 토대로 특성에 대한 영향을 분석하였다.

• Restorative Dentistry and Endodontics
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• v.34 no.5
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• pp.450-459
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• 2009

The aim of this study was to measure the initial dynamic modulus changes of light cured composites using a custom made rheometer. The custom made rheometer consisted of 3 parts: (1) a measurement unit of parallel plates made of glass rods, (2) an oscillating shear strain generator with a DC motor and a crank mechanism, (3) a stress measurement device using an electromagnetic torque sensor. This instrument could measure a maximum torque of 2Ncm, and the switch of the light-curing unit was synchronized with the rheometer. Six commercial composite resins [Z-100 (Z1), Z-250 (Z2), Z-350 (Z3), DenFil (DF), Tetric Ceram (TC), and Clearfil AP-X (CF)] were investigated. A dynamic oscillating shear test was undertaken with the rheometer. A certain volume ($14.2\;mm^3$) of composite was loaded between the parallel plates, which were made of glass rods (3 mm in diameter). An oscillating shear strain with a frequency of 6 Hz and amplitude of 0.00579 rad was applied to the specimen and the resultant stress was measured. Data acquisition started simultaneously with light curing, and the changes in visco-elasticity of composites were recorded for 10 seconds. The measurements were repeated 5 times for each composite at $25{\pm}0.5^{\circ}C$. Complex shear modulus G*, storage shear modulus G', loss shear modulus G" were calculated from the measured strain-stress curves. Time to reach the complex modulus G* of 10 MPa was determined. The G* and time to reach the G* of 10 MPa of composites were analyzed with One-way ANOVA and Tukey's test ($\alpha$ = 0.05). The results were as follows. 1. The custom made rheometer in this study reliably measured the initial visco-elastic modulus changes of composites during 10 seconds of light curing. 2. In all composites, the development of complex shear modulus G* had a latent period for $1{\sim}2$ seconds immediately after the start of light curing, and then increased rapidly during 10 seconds. 3. In all composites, the storage shear modulus G" increased steeper than the loss shear modulus G" during 10 seconds of light curing. 4. The complex shear modulus of Z1 was the highest, followed by CF, Z2, Z3, TC and DF the lowest. 5. Z1 was the fastest and DF was the slowest in the time to reach the complex shear modulus of 10 MPa.