https://oak.chosun.ac.kr/handle/2020.oak/18308 2025-08-30T03:14:08Z https://oak.chosun.ac.kr/handle/2020.oak/19360 Title: 성형작약 제트를 이용한 Ammonium DiNitramide (ADN) 단일추진제 추력기 성능 분석 Author(s): 엄태호; 김익태; 이창열 Abstract: A performance analysis using CFD (Computational Fluid Dynamics) simulation was carried out for the solid propellant engine based on shaped charge jet. The purpose of this study is to find the optimal thrust efficiency geometry according to the change of propellants and nozzle shapes. In order to improve the thrust efficiency in relation to weight, the shape and weight of the engine were modified with the shaped charge principle. The thrusters of various shapes were modeled, and thrust performance was analyzed through CFD simulations. The results show that the shape of the propellants and nozzles using the shaped charge jet was the efficient thruster modeling relative to weight. 2019-12-31T15:00:00Z https://oak.chosun.ac.kr/handle/2020.oak/19357 Title: 레이저 간섭계를 이용한 GFRP평판의 충격속도에 따른 손상평가 Author(s): 김정호; 김지훈; 김대영; 장호섭; 신광수 Abstract: The recent development of techniques in high-tech industries can be categorized into technical advances for safety and convenience and mechanical technology advancements for being ecologically friendly and lightweight. Under such circumstances, GFRP (Glass Fiber Reinforced Plastics), which is one of the representative lightweight materials, has attracted attention. In this study, GFRP flat plate, which is one of the composite materials for light weight, was subjected to free fall and high speed impact through GFRP flat plate to evaluate internal damage by external force such as external impact. The internal damage was evaluated and the following conclusions were obtained. In the damage evaluation according to the impact velocity of the GFRP plate, even if the impact energy collides with the same impact energy, the smaller the mass of the impact body and the faster the speed, the larger the damage amount in the impact. Therefore, it is possible to evaluate the damage of GFRP plate by shearography. 2019-12-31T15:00:00Z https://oak.chosun.ac.kr/handle/2020.oak/19353 Title: 국내산 개똥쑥 소수성 분획물의 항산회 활성 및 항주름 효과 탐색 Author(s): 김수민 Abstract: Artemisia annua belongs to the plant family of Asteraceae and is an annual short-day plant. This plant is known for its various effects such as its anti-cancer, anti-antioxidant, anti-inflammatory, and cardiovascular disease therapies. However, the anti-wrinkle effect of the hydrophobic fraction extract has not been reported yet. In this study, the antioxidant activity and anti-wrinkle activity of the number of hydrophobic fractions of domestic Artemisia annua L is investigated. Three solvent extracts (hot water, 70% ethanol, and 100% methanol) of Artemisia annua L are prepared. In the evaluation results of Artemisia annua L. leaf, antioxidant and anti-wrinkle activities are uncovered. The 100% methanol extract shows the highest antioxidant activities and total phenolic and total flavonoid contents among them. Collagenase inhibition, ellstase inhibition, and hyaluronidase inhibition IC50 rate are 124, 200, and 324 ug/mL, respectively. Therefore, this plant would be a useful anti-wrinkle cosmetic material. 2019-12-31T15:00:00Z https://oak.chosun.ac.kr/handle/2020.oak/19358 Title: 인버터 저항 용접기의 냉각 성능 개선이 용접 특성에 미치는 영향에 대한 연구 Author(s): 박현; 최병기 Abstract: The DC current was utilized for welding in inverter resistance spot welding machines. Also, a diode rectifier as a DC power supply had been used in the current resistance welding machines. In the process of rectifying an alternating current into a direct current by a diode rectifier, heat could be generated in the diode and, when overheated, the performance of the resistance welding machines might become unstable or could be set on a fire. In order to prevent these phenomena, the size of the diode assembly has been greatly increased by the amount of current required when outputting a high voltage current. In order to prove the effect of improving the cooling performance of the inverter resistance welding machines on welding characteristics, impact tests, leak tests, and tensile tests were all performed. This study aims at improving the cooling performance and rectifying the diode rectifier for the transformer of the inverter resistance spot welder for both rectifying a large amount of current and reducing the size of the external shape in order to produce stable welding characteristics. 2019-12-31T15:00:00Z