• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.217-223
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• 2018

This study to search the diagnostic performance of shear wave elastography(SWE) in breast mass and to compare the biopsy result and stiffness obtained from shear wave elastography. Diagnostic breast ultrasonography and SWE were targeted for 157 patients who had breast ultrasonography was diagnosed mass from June 2017 to September 2017. Pathology results of 157 patients showed a benign 92 patients(Age, $44.54{\pm}11.84$) and a malignancy 65 patients(Age, $51.55{\pm}10.54$). Final evaluation, biopsy result, and quantitative SWE result were obtained and compared with each other according to Breast Imaging Reporting and Data System(BI-RADS) of diagnostic breast ultrasonography. Quantitative SWE value and pathologic result showed the highest diagnostic specificity of 83.70% in Emean and sensitivity of 89.23% in Emin. Quantitative SWE result and biopsy result is statistically significant.(p=0.000). The optimal cut-off value for malignant lesions was 66.3 kPa and 63.7 kPa, respectively, for the sensitivity, specificity, high maximum mean elasticity value(Emax) and mean elasticity value(Emean) and this showed the highest diagnostic area under the ROC curve(Az) value compared to other SWE measurement(p=0.000). The addition of SWE to conventional US in breast mass make a increase diagnostic specificity and reduce unnecessary biopsy. Therefore, it is expected that it will be helpful to analyze the breast mass using the above analysis and apparatus.

• Journal of Korean Academy of Nursing
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• v.50 no.1
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• pp.66-80
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• 2020

Purpose: This study aims to examine the effects of nursing interventions based on the Extended Theory of Planned Behavior (ETPB) regarding self-efficacy for exercise (SEE), physical activity (PA), physical function (PF), and quality of life (QOL) in patients with lung cancer who have undergone pulmonary resection. Methods: This quasi-experimental study was conducted between July 2015 and June 2018 in two university-affiliated hospitals. The intervention included pre-operative patient education, goal setting (action and coping planning), and feedback (behavior intention and perceived behavioral control). The intervention group (IG) (n=51) received nursing interventions from the day before surgery to 12 months after lung resection, while the comparison group (CG) (n=36) received usual care. SEE, PA, PF (dyspnea, functional status, and 6-minute walking distance [6MWD]), and QOL were measured before surgery and at one, three, six, and 12 months after surgery. Data were analyzed using the χ² test, Fisher's exact test, Mann-Whitney U test, t-test, and generalized estimation equations (GEE). Results: There were significant differences between the two groups regarding SEE (χ²=13.53, p=.009), PA (χ²=9.51, p=.049), functional status (χ²=10.55, p=.032), and 6MWD (χ²=15.62, p=.004). Although there were no time or group effects, the QOL mental component (Z=-2.78, p=.005) of the IG was higher than that of the CG one month after surgery. Interventions did not affect dyspnea or the QOL physical component. Conclusion: The intervention of this study was effective in improving SEE, PA, functional status, and 6MWD of lung cancer patients after lung resection. Further extended investigations that utilize ETPB are warranted to confirm these results.

• Elastomers and Composites
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• v.55 no.2
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• pp.137-146
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• 2020

Part 1 provides a theoretical introduction of the hydrolysis mechanism, while Part 2 introduces other types of reaction mechanisms after hydrolysis in elastomer and PA66 composites. We reviewed the condensation reaction, which occurs after hydrolysis in bi-functional alkoxy silane (TESPD & TESPT), and investigated its effects on the mechanical properties of the composites. We also reviewed activators such as zinc soap, which enhances the mechanical properties of silica-silane-filled elastomer composites. The interaction parameter of silica-silane-filled elastomer composites [α_C (alpha C)] were also discussed. The effects of hydrolysis on the mechanical property changes in plastic composites were compared and reviewed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.346-349
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• 2001

Nowadays the amount of plastic products is increasing in modern industry. Plastic materials are continuously developed to satisfy the mechanical, physical, and chemical properties. The increasing application of plastic parts in automobile and aerospace industries is due to the fact that it can reduce the structural weight and can lessen the environmental contamination. Among many manufacturing technologies for plastic parts, the injection molding process is very attractive because of its low cost and short production time. Through various analyses of resin flow and molding process for the conventional gate and cooling mechanism, a new type of mold was designed which had different gate location and cooling systems. Newly designed ball seat has an excellent performances, i.e. diminished weld-line, residual stress density, higher magnitude less crack propagation and smaller dimensional contractions effect.

• The Korean Journal of Zoology
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• v.38 no.1
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• pp.115-124
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• 1995

한국산 거머리 각배obdeffo linea약의 상피조직을 배부상피(dorsal epithelium), 복부 상피(ventral epithelium) 측부상피(lateral epithelium) 별로 3부위를 광학현미경과 전자현미경으로 관찰한 결과 다음과 같은 결론을 얻었다. 전자현미경 관찰에서 거머리 상피조직은 3부위 모두 불규칙한 세포로 구성되었으며, 그들은 전자밀도가 높은세포와 중등도인세포 그리고 투명한세포 등 3종류로 구분되었다. 거머리의 불규칙한 상피조직 사이에서 두 종류의 분비성 과립인 a 및 b형과립과 색소성 과립인 D형과립이 관찰되었다 배부상피조직에서 관찰된 a형과립(66$\times$83 Um)은 복부와 측부에서 관찰된 과립(33H66 Um) 보다 형태가 훨씬 크고 그 수 도 두배정도 많이 관찰된 반면, b형과립은 모든 상피조직에서 동일한 크기와 형태를 보였지만 그 수는 배부와 복부에 비해 측부상피조직에서 두배정도 많이 관찰되었다 이상 분비성 과립들은 PAS-alcian blue(pH 2.5) 반응에서 모두 PAS에 강한 양성반응을 나타내어 중성점액다당류로 확인되었다. 거머리 몸마디를 이루는 체절은 배부와 복부에서 그 주름의 깊이와 넓이가 각각 다르게 나타나서(배부, 40 Um와 330 urn, 복부 100 urn와 150 urn), 복부의 깊은 체절이 발(foot)의 역활을 수행 하였다.

• Elastomers and Composites
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• v.55 no.4
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• pp.339-346
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• 2020

We functionalized a wear-resistant carbon-based MoS2 filler to solve its limited wear condition problem. The filler exhibits excellent lubricative properties. The surface modification of MoS2 was carried out using a (3-glycidyloxypropyl)trimethoxysilane (GPTMS) silane coupling agent to improve the low compatibility and dispersibility of the filler that generally degrade the performance of composites. A silane coupling agent was employed for the functionalization of MoS2, and its effect on the wear resistance of MoS2/Polyamide-6,6 was investigated. The silanization of MoS2 was identified by contact angle analysis and Fourier-transform infrared, energy dispersive X-ray, and X-ray photoelectron spectroscopies. The wear resistance of the composite was found to be improved significantly by the surface functionalization of MoS2.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.365-371
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• 2013

Purpose: In this study, we evaluated the physical and thermal properties of the compositions made by blending glass fiber (GF) of different contents into glass fiber polyamide-66, and investigated if the compositions applying to the glasses frame to replace the TR-90, which is polyamide-12 resin used as an injection-type spectacle frame material. Methods: To investigate the characteristics change of polyamide-66 (PA-66) compositions with the change of the content of glass fibers, we produced a composition of the content by using a twin-screw extruder. The mechanical strength of the composition production was measured and coating properties as well as cutting processability were evaluated. We evaluated the applicability of the glasses frame by comparison the results of new compositions with characterizations of traditional TR. Results: For the results of the characterization of Polyamide-66/GF composition, we found that the higher increase of content of the glass fiber, the less mold shrinkage rate, and the mechanical strength was increased. Tensile strength increased from $498kg/cm^2$ for 0 wt% of the content of the glass fibers to $849kg/cm^2$ for 30 wt% of the content of the glass fibers. As a result of a coating evaluation, the strength of coating was 4B in the GF 5wt% and 5B, which was extremely good coating characteristics, in the over than GF 5 wt%. Conclusions: In case that 30 wt% of the glass fiber was blended, the mechanical strength was greatly improved, the hardness was increased, injection temperature increased due to increase of the viscosity, and the flow mark of the product may occur. The paint coating of PA-66 blended with glass fiber was all excellent. With general evaluating physical properties and workability properties it was determined that around 10 wt% of the content of the glass fibers was possible to apply a spectacle frame.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.70-73
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• 2017

The dielectric constant and loss of poling/non-poling was measured in the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ samples. The addition of $La^{3+}$ to the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ did not cause a large change in grain size. But the addition of $La^{3+}$ did show transition temperature, which shifted toward low temperature in the $Pb[(Mg_{1/3}Ta_{2/3})Zr]O_3$ systems. In addition, the dielectric and pyroelectric properties (${\varepsilon}{\sim}20000$, $p{\sim}0.03C/m^2K$) of this system using $La^{3+}$ have been greatly improved. Pyroelectrics $Pb_{0.97}La_{0.02}(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ system was found to have a relatively high ferroelectric FOMs ($F_V{\sim}0.035m^2/C$, $F_D{\sim}0.52{\times}10^{-4}Pa^{-1/2}$) at room temperature. Spontaneous polarization showed a value of $0.27{\sim}0.35C/m^2$ in the composition added to $La^{3+}$. The piezoelectric constant ($d_{33}=350{\sim}490pC/N$) and electromechanical coupling factor ($k_P=0.25{\sim}0.35$) are obtained in $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ compositions with $La^{3+}$ dopant.

• Tribology and Lubricants
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• v.35 no.1
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• pp.1-8
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• 2019

Demand for plastic gears are increasing in many industries due to their low production cost, light weight, applicability without lubricant, corrosion resistance and high resilience. Despite these benefits, utilizing plastic gears is limited due to their poor material properties. In this work, DLC coating was applied to improve the tribological properties of polyamide66 gear. 0 V, 40 V, and 70 V of negative bias voltages were selected as a deposition parameter in DC magnetron sputtering system. Pin-on-disk experiment was performed in order to investigate the wear characteristics of the gears. The results of the pin-on-disk experiment showed that DLC coated polyamide66 with 40 V of negative bias voltage had the lowest friction coefficient value (0.134) and DLC coated PA66 with 0 V of negative bias voltage showed the best wear resistance ($9.83{\times}10^{-10}mm^3/N{\cdot}mm$) among all the specimens. Based on these results, durability tests were conducted for DLC coated polyamide66 gears with 0 V of negative bias voltage. The tests showed that the temperature of the uncoated polyamide66 gear increased to about $37^{\circ}C$ while the DLC coated gear saturated at about $25^{\circ}C$. Also, the power transmission efficiency of the DLC coated gear increased by about 6% compared to those without coating. Weight loss of the polyamide66 gears were reduced by about 73%.

• Design & Manufacturing
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• v.17 no.3
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• pp.55-60
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• 2023

The fiber-reinforced plastics and cellular injection molding process can be used to efficiently reduce the weight of battery housing components of mild hybrid electronic vehicles(MHEV) made of metal. However, the fiber orientation of fiber-reinforced plastics and the growth of foaming cells are intertwined during the injection molding process, so it is difficult to predict the mechanical properties of products in the design process. Therefore, it is necessary to evaluate the mechanical properties of the materials prior to the efficient stiffness design of the target product. In this study, a study was conducted to evaluated the mechanical properties of fiber reinforced cellular injection-molded specimens. Two types of fiber-reinforced plastics that can be used in the target product were evaluated for changes in tensile properties of cellular injection-molded specimens depending on the foaming ratio and position from the injection gate. The PP and PA66 specimens showed a decrease of tensile modulus and strength of approximately 30% and 17% depending on the foaming ratio, respectively. Also, the tensile strength decreased approximately 26% and 17% depending on the position from the injection gate, respectively. As a result, it was confirmed that the PP specimens have a significantly mechanical property degradation compared to the PA66 specimens depending on the foaming ratio and position.