• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.48.2-48.2
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• 2009

Ti와 Ti-6%Al-4%V합금은 내 부식성 및 생체 적합성이 매우 우수하기 때문에 현재 생체재료로써 널리 사용되고 있다. 하지만 Ti-6%Al-4V합금에 포함된 Al과 V이 신체에 좋지 않은 영향을 줄 수 있다는 연구 결과가 보고되면서 새로운 생체재료의 연구가 활발히 진행되고 있다. 본 연구에서는 생체에 무해한 Ti-Nb와 hydroxyapatite(HAp)를 복합 첨가하여 고에너지볼밀링(high-energy mechanical milling, HEMM)으로 나노 합금분말을 제조 후 급속소결에 의하여 Ti-Nb/HAp 생체재료를 제조 하였다. 제조한 Ti-Nb/HAp 생체용 복합재료에서 HAp 첨가량과 분말의 밀링, 믹싱에 따른 조직 변화와 소결체의 생체적합성의 변화 및 기계적 특성의 변화를 분석하였다. 이때 Ti-42%Nb에 HAp의 첨가량을 0%, 5%, 10%, 15%로 변화를 주었고, 밀링은 고에너지볼밀링기를 이용하여 0~8시간 동안 실시하였다. 그 결과 밀링 시간이 증가할수록 합금 분말의 크기가 미세해졌으며, 특히 8시간 밀링시 분말의 크기가 나노 크기로 감소하여 기계적 특성(경도 및 강도)이 우수해지는 것을 알 수 있었다.

• Composites Research
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• v.31 no.6
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• pp.398-403
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• 2018

Recently, environmental pollution caused by plastic waste, ecosystem disturbance of micro-plastics and human body accumulation are becoming big problems. In order to replace the traditional plastic, eco-friendly resin and natural fiber-based composite materials have been developed, but they have a disadvantage that their mechanical properties are significantly lower than those of synthetic fiber-based composites. In this study, eco - friendly nanofiber was extracted from seaweed and used as an additive in order to improve the mechanical properties of jute fiber-reinforced composites. Through the hand lay-up process, the composites were fabricated, and it was confirmed that the nanofiber was effective in improving the mechanical properties of natural fiber composites through tensile, bending and drop weight impact tests.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.207-214
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• 2023

Ships emit significant amounts of air pollution. To reduce ship emissions, the government has implemented the Eco-Friendly Ship Act to improve the marine air environment, under which the use of eco-friendly ships that use eco-friendly energy as a power source encouraged and technologies to reduce marine pollution are developed. Therefore, the revision of relevant laws and systems such as inspection and facility standards for the safe operation of eco-friendly ships is urgently needed, especially those for fishing vessels, which account for the majority of domestic coastal vessels. This study defines the core equipment for the application of electric complex propulsion systems to fishing boats and presents a minimum safety standard plan for the adoption and dissemination of eco-friendly fishing boats.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.169-175
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• 2019

The purpose of this study was to determine whether changes of multiple lying position might effect the convergence pulmonary function of the 20s men of mild intellectual disabilities. Twenty subjects of mild intellectual disabilities were participated in the experiment. Subjects were assessed for vital capacity by using Fit mate according to the multiple lying position changes(supine position, right sidelying position, left sidelying position, prone position). One-way repeated ANOVA analyzed each region data of vital capacity of subjects according to their multiple lying position. The result of the experiment showed that the 20s men of mild intellectual disabilities have more higher vital capacity to right sidelying position than another lying position. This study suggests that the pulmonary functional data of 20s men of mild intellectual disabilities in this experiment can be used as a basic respiratory one for the bed exercise programs in the area of the physical activities.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.763-769
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• 2010

In recent times, there has been considerable interest in HIPS (High Impact Polystyrene) materials for their use in construction of office equipments, home electronics, housing for electronics appliances, packing containers, etc. However, these materials suffer from problems caused by fatigue fracture. Further, their strength is substantially affected by environmental conditions. Therefore, in this study, the effect of temperature was analyzed by performing a tensile test and a fatigue test. It was observed that the yield strength, the ultimate strength, and the fatigue life decreased relatively with an increase in temperature. Further, an S-N curve can be predicted by using the results of the tensile test and a micro-Vickers hardness test.

• Journal of the Korea Convergence Society
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• v.12 no.9
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• pp.121-126
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• 2021

The purpose of this study is to investigate the effect of balloon blowing exercise on multiple pulmonary function and maximum voluntary ventilation in patients with mild intellectual disabilities in their 20s. 10 people in the experimental group and 10 people in the control group participated in the experiment. The experimental group performed the balloon blowing exercise for 30 minutes a day, and the control group performed the diaphragm breathing exercise for 30 minutes each. The subjects measured voluntary capacity and maximal voluntary ventilation using Fitmate before and after the experiment. Subjects were assessed with Vital capacity(VC) and Maximal voluntary ventilation(MVV) before and after the test and the results were compared with the paired t test. Data analysis was performed with SPSS win 18.0. After the experiment, the experimental group showed higher lung capacity and maximum ventilation than the control group. Through this study, the experimental group increased voluntary capacity and maximum voluntary ventilation more than the control group. It is thought that the quality of life can be improved if we continuously manage the health of intellectuals by developing various breathing exercise programs.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.7-12
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• 2005

The objective of this study was to evaluate the effects of nanofiller content on the microhardness and polymerization of experimental microhybrid composites. The nanofiller contorts in the experimental composites were varied (0%, 1%, 2%, 3%), while the total filler content remained constant as 76%wt. We obtained the following results: 1. The microhardness of the top surface for the 2% 3% nanofilled microhybrid composites were significantly higher than those for the 0%, 1% nanofilled composites (p<0.05), but the difference was not great. 2. The microhardness of the bottom surfaces significantly increased with an increase in the nanofiller level (p<0.05), except between the 2% and 3% nanofilled groups (P>0.05). 3. As the nanofiller level increased, the difference between microhardness of top and bottom surfaces significantly decreased (p<0.05), except between 2% and 3% nanofilled groups (p>0.05).

• Restorative Dentistry and Endodontics
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• v.36 no.2
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• pp.108-113
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• 2011

Objectives: To determine the effect of the spectral output of single and dual-peak light emitting diode (LED) curing lights on the microhardness and color stability of commercial resin composites formulated with camphorquinone and alternative photoinitiators in combination. Materials and Methods: Three light-polymerized resin composites (Z100 (3M ESPE), Tetric Ceram (Ivoclar Vivadent) and Aelite LS Posterior (Bisco)) with different photoinitiator systems were used. The resin composites were packed into a Teflon mold (8 mm diameter and 2 mm thickness) on a cover glass. After packing the composites, they were light cured with single-peak and dual-peak LEDs. The Knoop microhardness (KHN) and color difference (${\Delta}E$) for 30 days were measured. The data was analyzed statistically using a student's t-test (p < 0.05). Results: All resin composites showed improved microhardness when a third-generation dual-peak LED light was used. The color stability was also higher for all resin composites with dual-peak LEDs. However, there was a significant difference only for Aelite LS Posterior. Conclusions: The dual-peak LEDs have a beneficial effect on the microhardness and color stability of resin composites formulated with a combination of camphorquinone and alternative photoinitiators.

• Geotechnical Engineering
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• v.31 no.5
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• pp.20-28
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• 2015

• Proceedings of the KWS Conference
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• 1992.04a
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• pp.78-80
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• 1992