• 대한치과교정학회지
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• 제24권1호
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• pp.87-94
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• 1994

The purpose of this study was to evaluate the torque effect of othodontic wires. Ten types of orthodontic wires (five types of materials, two types of cross-sectional dimensions) were selected. Each group of ire type was constituted with five specimens. These specimens were tested on the universal testing machine(Instron) with specially-designed jig. The torque-twist curve of each wire was obtained and the results were analyzed statistically. The results were as follows. 1. 0.017'$\times$ 0.025' wire showed more torque effect than 0.016'$\times$ 0.022' wire at the same twist. 2.Torque effect was the greatest in stainless steel and the least in Nitinol. 3.The maximum amount of torque was the greatest in heat-treated Blue Elgiloy and the least in Nitinol.

• Journal of Biosystems Engineering
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• 제26권2호
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• pp.105-114
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• 2001

Modulus of elasticity, modulus of rigidity, damping ratio, and natural frequency of three varieties of boxthorn (Lycium chinense Mill) (Cheongyang #2, Cheongyang gugija, and Cheongyang native) branches were analyzed. Modulus of elasticity and modulus of elasticity and modulus of rigidity of the boxthorn branch was determined using standard formula after simple beam bending and torsion test, respectively, using an universal testing machine. Damping ratio and natural frequency of branches were determined using a system consisted of an accelerometer, a PC equipped with A/D converter, and a software for data analysis. Relationship between the elastic modulus and branch diameter in overall varieties and branch types showed a good correlation (r -0.81). There was, however, no correlation between torsional rigidity and branch diameter. The internal damping results were highly variable and the overall range of the damping ratio of the boxthorn branch was 0.014-0.087, which indicated that the branch was a lightly damped structure. The natural frequency of the boxthorn branch was in the range of 89-363 rad/s for the overall varieties and branch types. A good correlation (r 0.82) existed between the natural frequency and branch diameter in overall varieties and branch type.

• 소성∙가공
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• 제19권3호
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• pp.179-184
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• 2010

The present study is focused on the deep drawability and product qualities of ultra thin beryllium copper sheet metal. The goal of this research is to investigate the limit drawing ratio in deep drawing of ultra thin beryllium copper metal. For the experiment, beryllium copper(C1720, $50{\mu}m$ in thickness) is used. Tensile test are also carried out to find out the material properties. Deep drawing experiments are carried out in Universal Testing Machine(UTM) to obtain limit drawing ratio. Deep drawing tests are carried out for various specimen sizes. Teflon film is used as a lubricant and constant blank holding force is imposed. Sheet thickness and surface hardness are measured along radial direction after deep drawing. Thickness is measured using optical microscope. For beryllium copper(C1720), the maximum LDR of 2.4 is obtained when the die shoulder radius is 20 or 30 times of sheet thickness.

• 한국식품조리과학회지
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• 제10권4호
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• pp.351-356
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• 1994

Comparisions were made for cooking times, internal temperatures, thiamin contents and textural properties of various portion weights of egg mixture cooked in a microwave oven at high and/or low power levels and in a conventional double boiler. The mean internal temperatures of conventionally cooked egg mixtures were 76.4~80.7$^{\circ}C$. When cooking was made by steaming, the mean internal temperature were comparable among samples. With the microwave cooking, the range of mean temperature was 83.8~96.4$^{\circ}C$, and they were significantly higher than the conventionally cooked egg mixtures. The hardness determination was conducted using universal testing machine and a taste panel. Samples cooked with steam or with larger portion weight had softer texture than samples cooked by microwaves or smaller amount, respectively. Mean internal temperature was significantly(r=0.99, p<0.05) correlated with mechanical hardness determination. Statistical analyses indicated no significant difference in the thiamin content among various treatments.

• 한국산학기술학회논문지
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• 제1권2호
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• pp.15-20
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• 2000

본 논문에서는 교량 밑 건축구조물, 각종 기계부품의 진동문제를 보완하기 위한 방법으로서 MR유체를 이용한 댐퍼를 연구하였다. MR 유체의 특성을 이용한 댐퍼를 모델링하여, 설계도면을 기초로 MR 댐퍼를 제작하였다. 만능재료 시험기를 이용하여 주파수와 전류 및 변위를 단계적으로 변화시켜가며 성능실험을 반복적으로 수행하였다. 실험을 통하여 주파수, 전류 및 변위에 따라 댐핑 효과가 다르게 나타남을 확인할 수 있었다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2012년도 춘계학술논문집 1부
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• pp.363-366
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• 2012

본 연구에서 NaOH, Acetic acid, Silane 처리는 천연섬유와 matrix간의 계면 결합에 불리하게 작용하는 wax, lignin, hemicellose 등을 제거하기 위한 방법 중의 하나이다. 이러한 화학적 처리에 따른 왕겨 분말의 기계적 특성 변화를 관찰하였다. Scaning electron microscopy(SEM)으로 관찰한 표면의 상태가 NaOH, Acetic acid, Silane 처리를 하였던 왕겨 분말이 처리를 하지 않았던 왕겨 분말보다 비교적 깨끗해지고, 크랙이 발생함을 확인하였다. 또한 전처리가 된 상태에서 PP와 20, 30, 40%의 비율로 복합재를 제조하여 Universal Testing Machine(UTM)으로 인장강도, 굴곡강도, 굴곡탄성률을 측정하였다. 또한, 왕겨의 입도 사이즈에 따라서 어떻게 변화되는지 알아보았다.

• 대한치과보철학회지
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• 제37권5호
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• pp.651-657
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• 1999

This study was performed to investigate the retrievability of the cementation type implant abutments. The cements used in this study were Cavitec, Tembond and Zinc Phosphate Cement. The types of surface conditioning were no treatment, 50 microne sandblasting, 250 microne sandblasting, fine diamond finishing point and coarse diamond point. The retention of cast crown was measured with Instron Universal Testing Machine(Instron Engineering Co., U.S.A.). The results were as fellows: 1. The Maximium retention was obtained by the group of Z.P.C. cementation and Coarse diamond point surface conditioning. 2. Z.P.C. shows maximum retention, and reduced in orders Tembond, Cavitec, No cement. 3. The value of retention of surface condition was highest in coarse diamond point, lowest in no tretment. 4. The similar results were obtained between fine diamond point and 50 microne sandblasting, coarse diamond point and 250 microne sandblasting. 5. The were no direct corelation between mechanical retention and cementation retention.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.98-102
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• 2009

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. To manufacture the magneto-rheological fluid damper that uses such characteristics of the fluid, a flow analysis of the inner damper was conducted to forecast the damper's capacity. In addition, using the finite element method software, analysis on the characteristics of electromagnetic field around the coil operation unit inside the damper. Based on the result of the analysis, a single core damper and a double core damper were built and tested for their dynamic function. Based on the result of the experiment, the propriety of the flow analysis was demonstrated, and the proposed model was verified.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.295-299
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• 1996

Intrinsic Fabry-Perot Optical fiber sensors were embedded to tensile side of the 20cm$\times$20cm$\times$150cm cement concrete structures. The sensors were attached to the reinforcing steels and then, the cement concretes were applied. It took 30 days for curing the specimens. After that, the specimens were tested with 4-point bending method by universal testing machine. Strains were measured and recorded by the strain gauges embedded near optical fiber sensors. Output data of fiber sensor showed good linearity to the strain data from the strain gauges up 2000microstrain. The optical fiber sensors showed good response after yielding of structure while embedded metal film strain gauges did not show any response. We also specimens were broken down. In conclusion, the optical fiber sensors can be used as elements of health monitoring systems for cement concrete infra-structures.

• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.246-251
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• 2017

To fabricate a hydrocarbon polymer electrolyte composite membrane incorporated with Pt nanoparticle, the polymer electrolyte membrane made of a sulfonated-fluorinated hydrophilic-hydrophobic block copolymer (SFBC) and sulfonated poly (ether ether ketone) (SPEEK) blend in the wight ratio of 1 : 1 was synthesized, and a simple drying process was used in order to incorporate Pt nanoparticle into the SFBC/SPEEK film by reducing platinum (II) bis (acetylacetonate), Pt $(acac)_2$. The distribution of the Pt nanoparticles was observed by transmission electron microscopy (TEM), and mechanical and thermal properties were tested by universal testing machine (UTM) and thermogravimetry analyzer (TGA). Cation conductivity, ion exchange capacity (IEC) and I-V characteristics were estimated.