• Applied Biological Chemistry
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• 제38권2호
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• pp.151-156
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• 1995

하나하나의 우적(雨滴)과 여러개의 우적(雨滴)에 의한 토양의 분리(分離) (detachment)와 휘산(揮散) 침식(侵蝕) (splash erosion)을 연구하고자 미국 조지아주의 대표적인 농경지 토양 다섯 종류를 대상으로 우적탑(雨滴塔) (raindrop tower)과 인공강우기(人工降雨機) (rainfall simulator)를 이용하여 분리(分離) 실험을 수행하였다. 공시토양에 대하여 하나하나의 우적(雨滴)과 여러개의 우적(雨滴)에 의하여 일어나는 분리(分離)는 대부분 모래 크기의 입자로 비선택적이며, 토양의 이화학적 특성의 영향을 거의 받지 않는 경향을 보였다. 본 실험에 이용된 다섯 종류의 토양은 대부분 분산이 잘 되며 비교적 불안정하여 물방울에 의한 분리(分離)가 매우 쉽게 일어났으므로, 이들 토양 interrill 지역에서의 침식(侵蝕)은 분리(分離) 보다는 유출율 (runoff rate)에 의하여 결정됨을 알 수 있었다.

• 한국환경과학회지
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• 제15권2호
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• pp.177-183
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• 2006

The hydrolytic kinetics of biodegradable poly(l-lactide) (PLLA) have been studied by using two model systems, solution-grown single crystal (SC) and Langmuir monolayer techniques, for elucidating the mechanism for both alkaline and enzymatic degradations. The present study investigated the parameters such as degradation medium and time. The Langmuir mono layers of PLLA showed faster rates of hydrolysis when they were exposed to a basic subphase rather than they did when exposed to neutral subphase. Both degradation mediums had moderate concentrations to show a maximized activity, depending on their sizes. An alkaline degradation of SCs of PLLA showed the decrease of molecular weight of the remained crystals due to the erosion of chain-folding surface. However, the enzymatic degradation of SCs of PLLA occurred in the crystal edges thus the molecular weight of remained crystals was not changed. This behavior might be attributed to the size of enzymes which is much larger than that of alkaline ions; that is, the enzymes need larger contact area with monolayers to be activated.

• 환경생물
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• 제28권3호
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• pp.150-157
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• 2010

자연 토양 및 Burkholderia cepacia를 접종한 멸균 토양에 PBSA film을 매립하여 PBSA의 생분해 특성을 조사하였다. 상온에서 80일간 매립 시험을 실시한 결과, 자연 토양에서는 PBSA film의 34.0%, B. cepacia를 접종한 멸균 토양에서는 59.2%의 질량 감소가 일어났으며 PBSA film의 표면 형태 변화도 B. cepacia를 접종한 멸균 토양에 매립한 경우가 자연 토양에 매립한 경우에 비하여 PBSA film 표면의 침식 및 균열이 더 빠르게 일어났다. PBSA film을 매립하였을 때 80일 후 자연 토양에서 세균수는 6~7배 증가한 반면 B. cepacia를 접종한 멸균 토양에서 개체수는 10~14배 증가하였다.

• 한국표면공학회지
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• 제49권1호
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• pp.32-39
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• 2016

In this study, Al and Zn arc thermal spray coatings were carried out onto the substrate of SS400 steel to improve corrosion resistance and durability of hull structural steel for ship in marine environment. Therefore cavitation-erosion test was conducted to evaluate the durability of painted and thermal spray coated specimens. And then the damaged surface morphology and weight loss were obtained to compare with each other, respectively. As a result, the painted specimen was the poorest cavitation resistance characteristics because surface damage behavior appeared to be exfoliated in bulk shape during the cavitation experiment. And Zn thermal spray coating layer presented the significant surface damage depth due to relatively low surface hardness and local cavitation damage tendency. On the other hand, as a result of the weight loss analysis, the painting layer presented the poorest cavitation resistance and the Al thermal spray coating layer relatively showed the best results after cavitation experiment.

• 한국정밀공학회지
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• 제21권6호
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• pp.28-34
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• 2004

The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for brittle materials such as glass, silicon and ceramics, capable of producing micro structures larger than 100${\mu}{\textrm}{m}$. In this study, we introduced oblique powder blasting, and investigated the effect of the impacting angle of particles, the scanning times and the stand-off distance on the surface roughness and the weight-loss rate of samples with no mask, and the wall profile and overetching of samples with different mask pattern in powder blasting of soda-lime glass. The varying parameters were the different impact angles between 50$^{\circ}$ and 90$^{\circ}$, scanning times of nozzle up to 40 and the stand-off distances 70mm and 100mm. The widths of mask pattern were 0.2mm, 0.5mm and 1mm. The powder was alumina sharp particles, WA #600. The mass flow rate of powder during the erosion test was fixed constant at 175g/min and the blasting pressure of powder at 0.2Mpa.

• 지질공학
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• 제27권3호
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• pp.191-205
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• 2017

본 연구에서는 불투과형 사방댐과 링네트에 가해지는 충격하중을 평가하기 위해 토석류 모형축소실험을 수행하였다. 실험 결과, 토석류는 유체와 유사한 거동을 함에 따라 불투과형 사방댐 배면에 가해지는 토석류 충격하중은 하부구간이 4.14 kN로 가장 높게 작용하며 중간, 상부구간이 3.66 kN, 1.66 kN 가해지는 것으로 측정되었다. 링네트 실험결과 또한 불투과형 사방댐 결과와 같이 충격하중은 하부구간이 크며 상부로 갈수록 감소하는 경향을 보인다(2.28 kN, 1.95 kN, 1.49 kN). 수치해석 결과를 이용하여 토석류 흐름에 의한 토석류 방지시설 충격하중 흡수메커니즘을 분석한 결과, 불투과형 사방댐은 콘크리트 옹벽과 같이 구조물 자체의 강성을 이용하여 수평력에 저항하므로 실제 구조물에 작용한 수평력은 이론식과 유사한 결과가 제시되는 반면, 링네트는 강연선 탄성늘음과 네트 전면으로의 입자 투과를 이용하므로 충격하중은 사방댐 결과보다 최대 45% 감소하는 결과가 제시되었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제11권2호
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• pp.93-98
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• 2005

Studies on extended egg preservation schedule from 120 days to 180 days was taken up with 20 germplasm accessions of mutant silkworm genetic stocks of Bombyx mori L. Statistical analyses of the data collected over three trials revealed no significant changes both in the qualitative and quantitative traits of the genetic stocks between treatment (6 months egg preservation) and control (4 months egg preservation), except for fifth instar larval duration in TMS-61, TMS-62, TMS64, TMS-31 and TMS-34 shell weight in TMS-62, TMS-64 and TMS-66. Thus, the results indicate that extended schedule of 6 months egg preservation can safely be adopted, which will reduce the cost of conservation and minimize the genetic erosion owing to reduced crop cycle.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.344-350
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• 2001

Piping is a phenomenon where seeping water progressively erodes or washes away soil particles, leaving large voids (Pipes led to the development of channels) in the soil. Piping failure caused by heave can be expected to occur on the downstream side of a hydraulic structure such as fill dams when the uplift forces of seepage exceed the downward forces due to the submerged weight of the soil. The way to prevent erosion and piping and to reduce damaging uplift pressures is to use a protective filter or to construct cutoff wall/imperious blanket. Therefore, all the hydraulic structures faced/with soil materials should be taken the safety against piping into consideration.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.175-178
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• 2000

Biodegradability of the $poly({\beta}-hydroxybutyrate-co-3 -hydroxyvalerate)$ [PHB/V] containing 0, 10 and 15mol% hydroxyvalerate [HV] was studied. Bioderadability of PHB/V was evaluated at $30^{\circ}C$ for 58 days and $55^{\circ}C$ for 33 days by monitoring the time-dependent changes in weight loss(erosion) of aerobic conditions in a temperature-controlled microcosms containing the earthworm cast($30^{\circ}C$) and compost ($55^{\circ}C$). It was found that PHB/V biodegradability occurred with increasing HV monomer concentration from 0 mol% to 15 mol%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1422-1424
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• 1998

This paper deals with the surface aging and electrical characteristics of EPDM specimen with cooling and heating cycle. Then dielectric loss and weight loss are measered to evaluate electrical properties of EPDM on bulk and surface The specimens which underwent aging cycle over 600 hr reveal severe erosion on EPDM surface