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김연복,이희종,박철호,김동현,구현정,장광진,Kim, Y.B.,Lee, H.J.,Park, C.H.,Kim, D.H.,Koo, H.J.,Chang, K.J. 국립한국농수산대학교 교육개발센터 2018 현장농업연구지 = Journal of practical agricultural resear Vol.20 No.2
The aim of this study was to evaluate the change of phenolic compounds after phosphite treatment on Cheorwon onion. Onion is a perennial plant belonging to the lily family. It is native to Persia of Southwest Asia. It is widely cultivated in the temperate regions of the world. Onion is a good name for the 'Okchong' to drop blood cholesterol and cardiovascular blood flow to increase the prevention of adult diseases. Cheorwon area is inland, but it has high continental climate due to its high altitude. Therefore it is said that the onion cultivated in this region has higher sugar content and higher taste than onion grown in the southern region. Phosphorus components are particularly important ingredients for promoting muscle development. However, if the phosphoric acid content of the soil part is maintained to a large extent until the harvest, the competition of the nutrients tends to cause decay of the root part. Therefore, it is important to improve the quality and shelf life of onion by inducing nutrient balance by applying foliar fertilization method on the reducing phosphorus at harvest time. In this study, acidity was controlled by diluting phosphorous acid(H<sub>3</sub>PO<sub>3</sub>) and potassium hydroxide(KOH), followed by leaf surface treatment with phosphite on onion. In this study, the concentration of phosphite was diluted to 500, 1,000, 1,500ppm and sprayed three times over the onion leaves in May 2018 using an atomizer and harvested at the end of June, and the phenolic compounds were analyzed by HPLC. As a result, the content of quercetin, one of the important substances in onion, was phosphite 500ppm(179.70㎍/g), 1,000(150.27), 1,500(105.95). The contents of caffeic acid, p-coumaric acid, ferulic acid, rutin, kaempferol, and sugar content were higher in the treatments than in the control. Therefore, the phosphite does not have a great influence on the growth, but it may play a role as a method of achieving balance with nitrogen in the rainy season by supplying the role of the material catalyst and the water soluble phosphoric acid and the potassium in the influence of the material change.
김연복,김정 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.12
The dynamic compressive properties of a material at high strain rates are required for a finite-element analysis of dynamic environments such as a high-speed impact. In general, a split Hopkinson pressure bar (SHPB) apparatus can be used to evaluate dynamic compressive properties in the strain rate range of 102~104/sec. In this study, an SHPB apparatus was used to obtain the dynamic compressive properties of urethane, one of the soft materials. An analysis was carried out to increase the reliability of the urethane specimen against a low transmitted pulse by changing the properties of the pressure bar, adjusting the thickness of the specimen, and applying the pulse shaper technique. In addition, the experimental data were verified through a finite-element analysis using ABAQUS. 고 변형률 속도에 대한 소재의 동적 압축 물성은 고속 충돌 등 동적 환경에 대한 유한요소 해석을 위해 필수적으로 획득이 요구된다. 일반적으로 SHPB(split Hopkinson pressure bar) 장비는 102~104/sec의 변형률 속도 구간 내의 동적 압축 물성을 획득할 수 있다. 본 논문에서는 soft material 중 하나인 우레탄 소재의 동적 압축 물성 획득을 위해 SHPB 장비를 사용하였으며, 실험 시 압력봉의 물성 변경, 시편의 두께 조절, pulse shaper 기법 적용 등 우레탄 시편의 낮은 투과파(transmitted pulse)에 대한 신뢰도 증가 연구를 수행하였다. 또한 ABAQUS를 활용한 유한요소 해석을 통해 실험 데이터의 검증을 수행하였다.