This study investigates the thermal expansion characteristics of hydroxyl-terminated polybutadiene(HTPB) based solid propellants, focusing on batch-to-batch variability and accelerated aging effects. Coefficient of thermal expansion(CTE) measurements were conducted using thermomechanical analyzer(TMA) on samples from different manufacturing batches and specimens aged at various temperatures for different durations. Results indicate variations in CTE values between batches, highlighting the significance of manufacturing process control. Accelerated aging experiments reveal minimal systematic changes in CTE, suggesting stability of thermal expansion properties under short-term thermal stress. The overall distribution of CTE values shows concentration within a specific range, indicating consistency in thermal expansion characteristics. These findings provide insights into the thermal behavior of HTPB-based solid propellants, contributing to improved missile design and lifecycle prediction models.

In the aerospace field, Carbon/Cork composites have been used for rocket propulsion systems as a light weight structural component with a high bending stiffness and high thermal insulation properties. For the fabrication of a carbon composite with a heat insulation cork part, the bonding properties between them are very important to determine the service life of the Carbon/Cork composite structure. In this study, the changes in the interfacial adhesion and mechanical properties of Carbon/Cork composites under accelerated aging conditions were investigated. The accelerated aging experiments were performed with different temperatures and humidity conditions. The properties of the aged Carbon/Cork composites were evaluated mainly with the interfacial strength. Finally, the lifetime prediction of the Carbon/Cork composites was performed with the long-term property data under accelerated conditions.

노화란 시간경과에 따라 생체기능의 불가역적인 저하로 치매, 뇌혈관질환, 고혈압, 암 등과 같은 노화관련 질병이 생겨나며, 세포들이 생명력을 잃어가는 일련의 현상이다. 노화로 인한 대표적인 질병은 퇴행성 뇌 질환에 의한 알츠하이머, 치매와 파킨슨병이 있다. 이 병들은 초기의 변화가 두드러지지 않아 조기 진단이 어렵고, 질병의 진행을 막는데 어려움이 있다. 이를 해결할 방법으로 유전자 지표를 개발하는 것이 중요한 과제라 할 수 있는데, 본 연구는 노화 동물모델인 SAMP1 마우스를 대조군인 SAMR1 마우스를 비교하여 노화의 초기단계에 차등 발현하는 유전자를 확인하여 향후 노화와 연관 지표를 발굴하기 위하여 실시되었다. 먼저, 성장단계인 8주령과 노화초기진행단계인 26주령의 뇌 조직에서의 차등발현 유전자를 발굴하고자 cDNA chip 분석을 수행하였고, 신뢰성을 가지고 생물학적 변이를 검출할 수 있는 유전자는 13,939개의 유전자를 발굴하였다. 이들 중 발현이 2-fold 이상 증감하는 유전자들을 조사한 결과, 2,029개의 유전자를 선별할 수 있었다. 또한, 기능별로 분류한 결과 노화가 진행되는 과정에서 총 증가 혹은 감소한 유전자의 개수는 660개였으며, 이 중 노화와 연관성이 높은 유전자는 74개였다. 26주령에 증가양상을 보인 것이 46개, 감소양상을 보인 유전자가 28개로 밝혀졌다. 이를 검증하기 위해 노화와 관련된 유용한 유전자인 Wnt7a, Prkcb, Dgke가 선별되어 real-time qPCR을 수행하였다. 그 결과 Wnt7a 유전자는 노화가 진행됨에 따라 발현양이 급격히 감소하여 노화 초기 단계의 지표로 활용이 가능할 것으로 사료된다. 반면에 Prkcb 유전자는 성장단계의 발현량에는 관계없이 노화초기단계에서 억제됨을 확인하였고, Dgke는 성장단계부터 유전자 발현이 억제되어 노화에 영향을 미칠 것으로 판단된다.

The acoustic emission technique (AE) was implemented to assess long-term performance of concrete beams (reinforced with glass fiber reinforced polymers (GFRP) and steel bars) exposed to an aggressive combination of high temperature and humidity. This study presents the results and discussions of an experimental study concerning AE characteristics of long-term behaviors of concrete beams reinforced with GFRP and steel bars after accelerated

The responses of soybean seeds were evaluated to accelerated aging and gamma irradiation with regard to germination, seed leakage, seed leachate component and dry weight of hypocotyl and primary root of the germinating seed. Accelerated aging significantly reduced the final germination rate while gamma irradiation increased the final germination rate. Furthermore, the interactive effects occurred that the final germination rate of 5-day aged seeds increased considerably in response to 4 Gy of gamma irradiation. The extent to which the electrolyte was leaked from the seeds (conductivity) was significantly affected by accelerated aging and showed a close negative correlation with the germination rate. Gamma irradiation, however, did not significantly affect the electrical conductivity of seed leachate. The accelerated aging significantly increased the concentrations of the particular electrolytes leaked from the seeds while the gamma irradiation did not affect those concentrations. Of the electrolytes leaked from the seeds, Ca and Mg showed relatively lower concentrations while K showed greater concentrations than others. Moreover, N and P showed similar responses to aging treatment. Aging treatment significantly affected dry weight (DW) of hypocotyls and primary root. Also, gamma irradiation decreased DW of hypocotyls and primary root, particularly for 8 Gy associated with 5 days aging treatment. The data were discussed in terms of the relationships of seed vigor with aging treatment and gamma irradiation.

The objective of this study was to demonstrate whether or not the deleterious effects of accelerated aging on seed vigour and viability are alleviated by interaction with gamma irradiation. Seeds of soybean (Glycine max L.) were artificially aged and subsequently irradiated with 4 and 8 Gy of gamma irradiation. Germination rate was negatively affected by accelerated aging and positively by gamma irradiation, with a positive interaction of a 3day-seed aging treatment occurring with 4 Gy, possibly suggesting that 4 Gy of gamma irradiation partially offset the adverse effects of seed aging on germination. However, 5-day aged seeds did not gain any benefits from the gamma irradiation. Electrolyte leakage from the seeds increased with the duration in days aged. Irradiation, however, did not impose any effects on the leakage. Respiration rate of the seed with hypocotyl and primary root was significantly low for the aged seeds, but not for the seeds with both irradiation and aging treatments. Accelerated aging decreased the dry weight of the hypocotyl and primary root of the seeds without any measurable effects of irradiation. α -Amylase activity decreased with seed aging and positively responded to gamma irradiation. The data is discussed with regard to the possible roles of gamma irradiation for improving the seed vigour and viability of aged seeds.

Lipoxygenase가 결여된 진품콩(Lx1Lx1lx2lx2lx3lx3), 진품콩 2호(lx1lx1lx2lx2lx3lx3)와 L-1, L-2, L-3이 모두 존재하는 태광콩(Lx1Lx1Lx2Lx2Lx3Lx3)에 대한 종실특성과 인위노화 처리가 종실의 발아율에 미치는 영향을 알아보기 위하여 실시하였다. 1. 종피균열도는 3품종 모두 파종시기가 늦어짐에 따라 감소하였으며, 진품콩과 진품콩 2호가 태광콩보다 높았다. 2. 파쇄성과 경도는 진품콩과 진품콩 2호가 태광콩보다 낮아지는 경향을 나타내었다. 3. 발아율은 진품콩과 진품콩 2호가 태광콩보다 낮았고, 전기전도도는 인위노화 처리전보다 증가하였으며 태광콩, 진품콩, 진품콩 2호 순으로 높았다. 4. 발아율은 인위노화 처리기간이 길어짐에 따라 진품콩과 진품콩 2호가 태광콩보다 낮았으며, 전기전도도는 인위노화 처리기간이 길어짐에 따라 증가하였으며 진품콩과 진품콩 2호가 태광콩보다 높게 나타났다. 인위노화 처리 35일째는 태광콩과 진품콩이 비슷하게 나타났으며, 진품콩 2호는 태광콩과 진품콩보다 높게 나타났다. 5. 종피균열도는 발아율 및 인위노화 처리 후 발아율과는 유의적인 부의 상관을 나타내었다.