• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.202-202
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• 1999

The Polyethylene (PE), Polystyrene (PS) and Polytetrafluoroethylene (PTFE) surface modification was investigated by hydrogen io assisted reaction (H-IAR) in oxygen environment. The IAR is a kind of surface modification techniques using ion beam irradiation in reactive gas environment. The energy of hydrogen ion beam was fixed at 1keV, io dose was varied from 5$\times$1014 to 1$\times$1017 ions/$\textrm{cm}^2$, and amount of oxygen blowing gas was fixed 4ml/min. Wettability was measured by water contact angles measurement, and the surface functionality was analyzed by x-ray photoelectron spectroscopy. The contact angle of water on PE modified by argon ion beam only decrease from 95$^{\circ}$ to 52$^{\circ}$, and surface energy was not changed significantly. But, the contact angle using hydrogen ion beam with flowing 4ml/min oxygen stiffly decreased to 8$^{\circ}$ and surface energy to 65 ergs/cm. In case of PS, the contact angle and surface energy changes were similar results of PE, but the contact angle of PTEE samples decreased with ion dose up to 1$\times$1015 ions/$\textrm{cm}^2$, increased at higher dose, and finally increased to the extent that no wetting was appeared at 1$\times$1017 ions/$\textrm{cm}^2$. These results must be due to the hydrogen ion beam that cleans the surface removing the impurities on polymer surfaces, then hydrogen ion beam was activated with C-H bonding to make some functional groups in order to react with the oxygen gases. Finally, unstable polymer surface can be changed from hydrophobic to hydrophilic formation such as C-O and C=O that were confirmed by the XPS analysis, conclusionally, the ion assisted reaction is very effective tools to attach reactive ion species to form functional groups on C-C bond chains of PE, PS and PTFE.

• 한국지반공학회논문집
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• 제19권4호
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• pp.155-165
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• 2003

본 연구는 고함수비의 액상준설토의 체적변화 및 퇴적특성을 파악하기 위해 일련의 실린더침강시험, 침투압밀시험과 2차원퇴적모형실험이 실시되었다. 그리고 실험결과는 실제 준설매립현장의 퇴적상태와 비교됨으로써 설계시에 필요한 침강에 의한 체적변화량을 구할 수 있도록 하였으며, 퇴적후의 세립토의 분포와 함수비 변화 등이 함에 조사되었다. 따라서 1차원 침강시는 실질토량이 증가 할 수록 퇴적고는 선형적으로 증가하며, 자중압밀개시시 및 완료시의 계면고도 또한 실질토량에 비례하여 증가되고 있다. 한편 2차원 퇴적모형실험에 의해 함수비의 분포와 세립토의 퇴적상태를 제시하였으며, 퇴적층의 함수비는 #200체의 통과량에 따라 다르며 최소 30%에서 최대 180%까지 폭넓게 분포되고 있다.

• Geomechanics and Engineering
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• 제14권3호
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• pp.283-291
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• 2018

Cracks in soil provide significant preferential pathways for contaminant transport and rainfall infiltration. Water exchange between the soil matrix and crack is crucial to characterize the preferential flow, which is often quantitatively described by a water exchange ratio. The water exchange ratio is defined as the amount of water flowing from the crack into the clay matrix per unit time. Most of the previous studies on the water exchange ratio mainly focused on cracked sandy soils. The water exchange between cracks and clay matrix were rarely studied mainly due to two reasons: (1) Cracks open upon drying and close upon wetting. The deformable cracks lead to a dynamic change in the water exchange ratio. (2) The aperture of desiccation crack in clay is narrow (generally 0.5 mm to 5 mm) which is difficult to model in experiments. This study will investigate the water exchange between a deformable crack and the clay matrix using a newly developed experimental apparatus. An artificial crack with small aperture was first fabricated in clay without disturbing the clay matrix. Water content sensors and suction sensors were instrumented at different places of the cracked clay to monitor the water content and suction changes. Results showed that the water exchange ratio was relatively large at the initial stage and decreased with the increasing water content in clay matrix. The water exchange ratio increased with increasing crack apertures and approached the largest value when the clay was compacted at the water content to the optimal water content. The effective hydraulic conductivity of the crack-clay matrix interface was about one order of magnitude larger than that of saturated soil matrix.

• Journal of Biosystems Engineering
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• 제25권6호
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• pp.481-488
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• 2000

This study was initiated in order to find alternative fuel substituting for light oil the most common fuel for heating greenhouse. The tire oil used in this research was produced by pyrolysis process, one of the final products besides steel string and carbon black in which waste tires as a form of chopped pieces broken by shredding machine are heated up to 200~30$0^{\circ}C$ with maximum restraining of oxygen supply. In order to justify light oil equivalent qualities in tire oil combustion characteristics were defined in the way of comparing kinetic viscosities in the wide range of temperature flame sizes and exhaust gas components in the various combustion conditions. We found that kinetic viscosity of tire oil was lower than light oil by 1 to 2 cSt in the temperature range showing better flowing mobility in the fuel line of the burner and no significant difference in flame size between the two oils in the all combustion treatments. However much more NO and SO$_2$ were detected from the exhaust gases of tire oil than light oil combustions. In fact tire oil contains more nitrogen and total sulfur, by 25 times and 40 times respectively than light oil according to the composition analysis. Tolerable limit for SO$_2$discharge amount defined by the national air pollution standards is under 540ppm so tire oil combustion satisfies the requirement though. It is desirable if sulfur and nitrogen filtering process shall be added in the tire oil production line. Except the exhaust gas components all greenhouse heating qualities of tire oil including hot air temperature are very identical to those of light oil.

• 한국통신학회논문지
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• 제19권12호
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• pp.2508-2519
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• 1994

본 논문은 국내 ISDN 망에서 상용전원 이상시에도 최소한의 음성서비스를 보장하기 위한 방법으로 망급전과 재충전 배터리를 사용하는 방안을 검토하였다. 망급전의 경우에서는 요구되는 선로전압 및 선로전류 등을 선로 종류 및 급전전력에 따라 시뮬레이션을 수행하였다. 이러한 시뮬레이션의 결과로서 현재 국내 ISDN 가입자 선로를 교체하지 않고는 망급전이 불가능한 것으로 나타났다. 따라서 급전 방법으로는 재충전 배터리 사용이 타당한 것으로 판단되며, 재충전 배터리 사용시에는 선로매듭에서 발생하는 부식에 의하여 접촉저항이 증가하는 문제를 해결하기 위하여 별도의 전류를 사용할 필요가 있다. 이러한 전류를 실링(sealing) 전류라 하는데 국내에서 개발된 ISDN 교환기의 가입자보드에서 실링전류 및 망급전 용으로 설치된 급전용 전력조정기를 사용하여 실험하였다. 실험 결과 실링 전류의 공급이 물리계층의 클럭동기에 영향을 주지 않으며, 매우 짧은 시간동안만 실링전류의 영향이 나타남을 확인하였다. 이러한 실링전류의 실험결과는 선로를 간략하게 모델링하여 시뮬레이션 한 결과와 완전히 일치하는 것으로서 실험이 정당함을 시뮬레이션으로 확인하였다.

• Archives of Pharmacal Research
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• 제29권8호
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• pp.707-711
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• 2006

Bifidobacteria-loaded alginate poly-l-lysine microparticles (bap microparticles) were prepared using an air atomization method and then freeze-dried. The viability of the bap microparticles was investigated as a function of the amount of the bifidobacteria cultures, and the addition of a yeast extract, cryoprotectants, antioxidants and neutralizer. The size of the bap microparticles with and without the bifidobacteria was $84.8{\pm}28.5\;{\mu}m$ ($mean{\pm}standard$ deviation) and $113.1{\pm}38.5\;{\mu}m$, respectively. The surface morphology was slightly ellipsoid and wrinkled regardless of the incorporating bifidobacteria. The viability gradually decreased with increasing freeze-drying time. Free-flowing powdered bap microparticles were obtained at least 12 h after freeze-drying the wetted slurry of bap microparticles. However, the particles tended to aggregate when either lactose or ascorbic acid was added. The addition of a yeast extract, cryoprotectants (glycerol and lactose), antioxidants ($NaHSO_3$ and ascorbic acid) and neutralizer $(Mg_3(PO_4)_2)$ resulted in a significantly higher viability of the bifidobacteria in the bap microparticles after freeze-drying (0.34-1.84 log) compared with the culture alone.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.682-685
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• 2017

본 연구는 비원형 Effervescent Type 이유체 노즐의 분사 특성을 조사하기 위한 실험적 연구를 수행하였다. 이를 위해 거의 동일한 노즐 출구 면적으로 가공한 2종류의 비원형 노즐 (E1, E2)과 1종류의 원형 노즐 (C)을 대상으로 비교 실험을 진행하였다. 이때 노즐에 장착된 Aerorator는 노즐 출구 면적과의 Aspect Ratio를 맞추기 위해 지름이 다른 3종류를 사용하였다. 따라서 각 노즐마다 3가지의 Aspect Ratio에 따라 3번의 실험을 진행하였으며, 전체 총 9종의 실험이 진행되었다. 실험은 Liquid의 유량을 고정시킨 후, 유입되는 Air의 양을 제어하며 진행하였으며, 노즐 내부 압력과 액적의 크기 (SMD)를 측정하고 노즐에서 분사 이미지를 촬영하였다. 이를 통해 3종의 노즐의 유량 계수를 압력 분무방정식과 Jedelsky 방정식을 비교 계산하였고, Jedelsky 방정식이 약 4배 정도 더 큰 값을 갖는 것을 확인하였다. 노즐에서 분사되는 SMD는 원형보다 비원형에서 더 작은 값을 갖는 것으로 나타났으며, 이는 유량 계수 값의 차이 의해 야기된 것으로 예상된다.

• 한국환경복원기술학회지
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• 제12권3호
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• pp.49-58
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• 2009

This study was done to provide a case model with a concept of environmental integration based on the water circulation system. Area of interest (AOI) is the Eastern Pangyo New Town area, which has several advantages in adaptation of a water circulation system. The AOI has a potential of maintaining water resources, and has a good condition to construct the water circulation system. Research done for the purpose of the establishment of the water circulation system in the Eastern Pangyo New Town shows the following. The main sources of water supply in the water circulation system in the Eastern Pangyo New Town is from two subway stations and runoff water, along with the natural water flowing from the mountains, rain water, and stream water. It was determined that more than 35,000 tons of water would be needed for the creation of water circulation system at the Eastern Pangyo. If the creation of infrastructure for the use of runoff and rain water as well as the periodic management can be provided, it can serve as the new model for a new city with water circulation system. In addition, since the Eastern Pangyo New Town water circulation system can secure enough amount of water resources, natural drainage system (NDS) in which it can be in dry condition in non-rainy days, is applied and connected to the typical waterways. Such water circulation system has many positive aspects including the wise use of water resources, and providing wild Life animals corridors and habitats. Also, the water circulation system can lead to the environmental education to the residents and visitors on environmental awareness of the water circulation system and their environment.

• 동의생리병리학회지
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• 제19권2호
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• pp.329-338
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• 2005

Breast milk is general term for crude milk and mature that is secrete after two-three days of delivery. Because amount of milk secretion is different, disorder of milk secretion is to be classified into galactostasis and spontanous flow of milk. According to this point, we considered thirty four papers and got the conclusion about the concept, cause, therapeutic method and medication of secreation disorder. Therefore we report the result. galactostasis due to deficiency of the qi and blood, depression of liver qi, blood stasis of postpartum, excessiveness and so on. If the qi and blood is deficient, therapeutic method is enriching qi and benefiting blood, if the liver qi is deprssive, treatment is relieving the deprssive liver and regulating the circulation of qi. The milk is flowing spontanously and continously due to a prosperous condition of qi and blood, too deficiency of the qi and blood, depression of liver qi and so on. If the qi and blood is deficient, therapeutic method is tonifying and arresting the qi and blood, if Liver channel is stagnated fire, puring the liver of pathologic fire, relieving the deprssive liver and regulating the circulation of qi. Clinical study for the 1 case of the recurrent cervical cancer patient.

• 한국산학기술학회논문지
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• 제22권4호
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• pp.287-294
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• 2021

삽교호로 유입하는 곡교천 유역의 홍수시 유출량을 추정하기 위해서 Tensorflow를 활용하여 파이썬 기반의 LSTM 모형을 구축하였다. 층의 깊이가 성능에 미치는 영향을 분석하기 위해, 은닉층의 깊이를 2, 4, 6층으로 증가시키면서, 선행시간 1시간부터 5시간까지 예측을 수행하였으며, 은닉층의 개수가 4개일 때가 가장 우수한 성능을 나타내었다. 학습에 사용하는 입력자료의 길이 즉, 시퀀스길이가 모형의 성능에 미치는 영향을 파악하고자 시퀀스길이를 3시간, 5시간, 7시간으로 증가시키면서 모형을 실행한 결과, 시퀀스길이가 3시간 일 때, 전 시간대에 걸쳐 예측 성능이 우수한 것으로 분석되었다. 모형 검증에서 극한 강우 3건에 대하여 예측을 수행한 결과 선행시간 1시간에 대하여 평균 NSE 0.96 이상의 높은 정확도를 나타내었으며, 선행시간 2시간 이상에 대하여 정확도는 점차적으로 낮아지는 것으로 확인되었다. 결론적으로 시퀀스길이 3시간을 사용하여 선행시간 1시간에 대한 예측을 수행한다면 곡교천 강청 관측소의 홍수위를 높은 수준의 정확도로 예측할 수 있음을 확인하였다.