• 한국세라믹학회지
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• 제29권2호
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• pp.95-100
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• 1992

A high-Tc superconducting phase was obtained using long sintering time of 210 hours. From XRD and SEM analyses, it could be confirmed that the particles were plate phase, of which the structure is tetragonal system with lattice parameter a=b=5.44${\AA}$, C=37.18${\AA}$. Resistance and current density measurements were carried out using 4 probe method. The experimental data revealed that the stable high-Tc superconducting phase was easily formed by addition of Pb to Bi-system. Therefore, we could find the sintering condition to synthesis the system having the largest fraction of high Tc phase.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 동계학술발표회 논문집
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• pp.87-88
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• 2008

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 추계학술대회 논문집
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• pp.71-72
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• 1988

• 한국재료학회:학술대회논문집
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• 한국재료학회 1993년도 춘계학술발표회
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• pp.130-131
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• 1993

• 대한화장품학회지
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• 제38권4호
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• pp.263-270
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• 2012

아스코르빅산(비타민 C)은 수용액상에서 공기와 빛, 알칼리 등에 의해 쉽게 불안정화되는 성질이 있어 화장품에 적용에 있어서 제한적이다. 아스코르빅산은 수용액상에서 불안정성에 영향을 주는 가장 중요한 인자인 공기, 특히 산소와 열, 빛 등의 외부환경에 민감하게 반응하여 산화에 의해 쉽게 분해되는 문제점이 있다. 본 연구에서는 이러한 아스코르빅산의 안정성을 증가시키고자 폴리올과 유화방법을 변화시켜 안정화하는 연구를 수행하였고 실온과 고온에서 색상과 아스코르빅산의 함량변화를 HPLC로 측정하여 비교하였다. 그 결과 실험한 조건들 중 폴리올은 글리세린을 사용한 경우 아스코르빅산의 안정화 가장 좋았으며 비수유화방법을 사용한 경우에 있어서 가장 안정하였다. 이러한 결과들로부터 아스코르빅산이 본 실험의 비수유화로 안정성이 증가하며 안정한 화장품을 만드는 데 적용이 가능하다.

• 공학논문집
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• 제3권1호
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• pp.215-222
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• 1998

촉매 연소용 촉매 담체인 $\gamma-Al_2O_3$ 분말의 열안정화에 미치는 La과 Si의 첨가 효과에 대하여 연구하였다. 첨가제의 첨가는 습식 impregnation방법으로 행하였고, 출발 물질은 $La(NO_3)_3{\cdot}6H_2O$와 $Si(OC_2H_5)_4$를 사용하였다. 열안정화 효과는 혼합분말을 고온에서 열처리 한 후 비표면적을 측정하여 고찰하였다. 첨가제로 첨가한 La과Si는 모두 순수한 $\gamma-Al_2O_3$분말에 비하여 소결을 억제함으로써 열 안정화 효과가 있음이 확인되었으며, 특히 Si 첨가한 경우에는 $\alpha-Al_2O_3$의 생성을 현저히 억제한다는 것을 확인하였다. 이들 첨가제에 의한 열안정화 효과는 첨가제에 의한 새로운 상의 생성과 표면 확산의 억제등이 주된 요인으로 판단되었다.

• 한국전문물리치료학회지
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• 제30권2호
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• pp.110-119
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• 2023

Background: Osteoarthritis is a common condition with an increasing prevalence and is a common cause of disability. Osteoarthritic pain decreases the quality of life, and simple gait training is used to alleviate it. Knee osteoarthritis limits joint motion in the sagittal and lateral directions. Although many recent studies have activated orthotic research to increase knee joint stabilization, no study has used patellar tendon straps to treat knee osteoarthritis. Objects: This study aimed to determine the effects of patellar tendon straps on kinematic, mechanical, and electromyographic activation in patients with knee osteoarthritis. Methods: Patients with knee osteoarthritis were selected. After creating the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), leg length difference, Q-angle, and thumb side flexion angle of the foot were measured. Kinematic, kinetic, and muscle activation data during walking before and after wearing the orthosis were viewed. Results: After wearing the patellar tendon straps, hip adduction from the terminal stance phase, knee flexion from the terminal swing phase, and ankle plantar flexion angle increased during the pre-swing and initial swing phases. The cadence of spatiotemporal parameters and velocity increased, and step time, stride time, and foot force duration decreased. Conclusion: Based on the results of this study, the increase in plantar flexion after strap wearing is inferred by an increase due to neurological mechanisms, and adduction at the hip joint is inferred by an increase in adduction due to increased velocity. The increase in cadence and velocity and the decrease in gait speed and foot pressure duration may be due to joint stabilization. It can be inferred that joint stabilization is increased by wearing knee straps. Thus, wearing a patellar tendon strap during gait in patients with knee osteoarthritis influences kinematic changes in the sagittal plane of the joint.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권4호
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• pp.237-248
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• 2015

"Dynamic stabilization" systems have been developed in recent years to treat degenerative disorders of the spinal column. In contrast to arthrodesis (fusion), the aim here is to conserve intervertebral mobility to maximize comfort. When developing innovative concepts, many mechanical tests need to be carried out in order to validate the different technological solutions. The present study focuses on the B Dyn$^{(R)}$ "dynamic stabilization" device (S14$^{(R)}$ Implants, Pessac, France), the aim being to optimize the choice of polymer material used for one of the implant's components. The device allows mobility but also limit the range of movement. The stiffness of the ring remains a key design factor, which has to be optimized. Phase one consisted of static tests on the implant, as a result of which a polyurethane (PU) was selected, material no.2 of the five elastomers tested. In phase two, dynamic tests were carried out. The fatigue resistance of the B Dyn$^{(R)}$ system was tested over five million cycles with the properties of the polymer elements being measured using dynamic mechanical analysis (DMA) after every million cycles. This analysis demonstrated changes in stiffness and in the damping factor which guided the choice of elastomer for the B Dyn$^{(R)}$ implant.

• 열처리공학회지
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• 제4권4호
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• pp.34-43
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• 1991

A small amount of misch metal and/or Zr was added as a dopant to 70.5wt----Cu-26wt----Zn-3.5wt----Al shape memory alloy in order to study the effect of grain refinement and heat treatments on the transformation behavior, stabilization of martensite, and shape memory ability. It was found that the addition of misch metal and Zr was very effective for reducing the grain size. The fracture mode has been changed from intergranular brittle fracture to ductile fracture with void formation and coalescence by the addition of misch metal and Zr. Aging of the ${\beta}$-phase decreases the $M_s$ temperature, but that of the martensite phase increases the $A_s$ temperature. The hysteresis of transformation temperature ${\Delta}T(A_s-M_s)$ has an increasing tendancy by grain refinement. The crystal structure of martensite was identified as monoclinic structure. As the grain size decreased, martensite stabilization more easily occured and the shape, memory ability has been reduced by the grain size refined.

• 대한화학회지
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• 제34권3호
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• pp.248-254
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• 1990

5각-이종원자 방향족 고리화합물들인 푸란, 피롤 그리고 티오펜과 이소프로필 양이온간의 친전자성 친환반응에 관하여 MNDO 방법을 사용하여 이론적으로 연구하였다. ${\alpha},{\beta}$ 그리고 이종원자 방향족 고리화합물의 HOMO간의 전하전이 안정화(Charge transfer stabilization) 효과에 의하여 주로 결정됨을 알 수 있었다. 한편 $\alpha$ 와 $\beta$ 위치에 대한 반응성의 순서는 피롤>푸란>티오펜의 순서를 가지며 이러한 순서는 기체상 및 용액상 실험결과와 잘 일치하는 것이다.