• 한국잠사곤충학회지
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• 제41권3호
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• pp.196-200
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• 1999

The flat-ways spinned cocoon was prepared from the silkworm using flat and circular type cocooning frame. The spinning rate of the silkworm was 76.9% compared to the normal mounted silkworm. The arrangement of cocoon baves of the flat-ways spinned cocoon was more linear than the normal cocoon which is curved. To maintain the size-stability of the flat-ways spinned cocoon, degumming process was treated with enzymes. These flat-ways spinned cocoons could be used as padding materials for the thermal insulations and decoration uses for the traditional fan which the silkworms are mounted directly on the fan frame.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.149-154
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• 2007

It is essential to know the heat transfer characteristics at the absorber plate of Flat-plate solar collector for optimum design. For flat-plate solar collector, it is difficult to experimentally study the effect for the Reynolds number of riser considering low mass flow rate being applied into the collector with one riser tube. So, this study were performed to show the heat transfer characteristics of flat-plate solar collector with single absorber plate and riser for various Reynolds number at riser using commercial code FLUENT 6.0. The base collector size is chosen with $0.4m^2$ as 0.2m by 2m with single riser in this study, Reynolds number at riser is from 200 to 1200 including about 530 at typical flat-plate collector with 10 risers considering the mass flow rate of 0.02kg/s per collector area for the certificate test Through the simulation, the results were presented as the temperature distribution at the absorber plate for various flow rate and solar irradiance conditions, then showed the effective length scale of the absorber plate The real solar irradiation condition is assumed as the constant heat flux condition of $500w/m^2$ considering the annual average solar irradiance in Korea.

• Ocean and Polar Research
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• 제28권2호
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• pp.119-127
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• 2006

We measured oxygen microprofiles using an oxygen microelectrode in Ganghwa intertidal flat in April and September. Oxygen consumption rate was calculated by using three different methods based on the oxygen microprofiles. The method using the PROFILE software was thought to be the most reliable among the three methods. The oxygen consumption rates calculated at station D1 by using the PROFILE software were 10.5 and 6.27mmol $m^{-2}d^{-1}$ in April and September, respectively. At station D2, they were 10.9mmol $m^{-2}d^{-1}$ in April and 5.39 mmol $m^{-2}d^{-1}$ in September. There was little spatial variation, but large seasonal variation, with almost two times larger values in April than in September. The higher rate in April is ascribed to higher oxygen concentration in the seawater and higher organic carbon content in the surface sediments, which probably accelerate oxygen consumption for organic matter decomposition in the sediments. Aerobic remineralization rates estimated from the oxygen consumption rates ranged from 4.14 to 8.07 mmol C $m^{-2}d^{-1}$ in Ganghwa intertidal flat, which were much lower than the anaerobic remineralization rate.

• Ocean and Polar Research
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• 제24권4호
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• pp.331-343
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• 2002

The southern tidal flat of Kanghwa Island with an area of approximately $90km^2$ is one of the biggest flats on the west coast of Korea. Surface sediments for sedimentary analyses were sampled at 83 stations in August 1997, September 1999 and August 2000. The very poorly-sorted mud sediments were predominant in the eastern part of the tidal flat, whereas the poorly-sorted sand-mud mixed sediments were dominant in the western part. The area of muddy sediment distribution diminished, but that of sandy mud sediment extended to southeastward tidal flat for three years. In the western part of tidal flat, deposition occurred during the period of spring to summer, whereas erosion occurred in winter. Sediment accumulation rates during three years indicated that the sediments deposited continuously in the eastern part of tidal flat, whereas eroded in the western part of tidal flat. Recently, construction of artificial structures such as new airport, island-connecting bridges and dikes near the tidal flat might change tidal current and river flow pattern. In order to reduce the ecological damage and to preserve tidal-flat environment, it is necessary to Investigate long-term impacts on sedimentary environment and ecology.

• Ocean and Polar Research
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• 제28권4호
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• pp.361-368
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• 2006

The Saemangeum tidal flat with an area of approxirnately $233km^2$ is one of the biggest estuarine tidal flats on the west coast of Korea. Because of its location in the estuary of Mangyeong and Dongjin Rivers, the tidal flat receives large amount of sediments. A 33-km long sea dyke, enclosing a coastal zone of $401km^2$, was constructed to reclaim tidal flat in the Saemangeum area. The dyke construction radically changes the local tidal current regime and estuarine circulation. These have an effect on sedimentary environments in the tidal flat. On the tidal flats of the study area net deposition occurred, but net erosion occurred near tidal channel in 2004. The comparison of topography and surface sediments in summer 2004 with those in summer 1988 before the dyke construction showed that elevation increased with maximum 80cm and mean grain sizes were fining at Gwanghwal tidal flats. Sedimentary facies of two cores from Gwanghwal tidal flat revealed homogeneous layers in the upper part suggesting rapid deposition after the dyke construction. The sedimentation rate in Gwanghwal tidal flat(GW 6) using $^{210}Pb$ analysis was about 5.4cm/yr which is well matched with the sedimentation pattern revealed by change in topography.

• 한국재료학회지
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• 제21권10호
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• pp.532-541
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• 2011

The Xe plasma flat lamp, considered to be a new eco-friendly LCD backlight, requires a further improvement of its luminance and luminous efficiency. To improve the performance of this type of lamp, it is necessary to understand the effects of the discharge variables on the luminous characteristics of the lamp. In this study, the luminous characteristics of a coplanartype Xe plasma flat lamp with a teeth-type electrode pattern were analyzed while varying the gas composition, gas pressure and input voltage. The effects of the phosphor layer on the discharge and the luminous characteristics of the lamp were also studied. The luminous efficiency of the coplanar-type Xe plasma flat lamp improved as the Xe input ratio and gas pressure increased. Higher luminous efficiency was also obtained when helium (He) was used as a buffer gas and when a phosphor layer was fabricated on the electrode region. In contrast, the luminous efficiency was reduced with increasing the input voltage. It was found that the infrared emissions from the lamp were affected by the Xe excitation rate in the plasma, the Xe gas density, the collisional quenching of excited Xe species by gas molecules, and the recombination rate between the Xe ions and electrons.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.209-214
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• 2002

Mechanical micro-engineering is an easy and cheap way to fabricate micro-structures. If the application of the conventional machining method using flat-end mill becomes available for the micro-manufacturing process, it will be advanced as an extension of the conventional machining process. In this study, micro-grooves cutting using flat-end mill(($\phi$8) was performed. The characteristics on flat-end milling was investigated to improve machinability of micro-grooves. The experiments were performed according to variations of spindle revolution, depth of cut, and feed rate. Machinability through various cutting conditions was evaluated by surface geometry, tool wear, and cutting force. The results show that micro V-grooves of width(pitch) 29${\mu}{\textrm}{m}$ were acquired by flat-end milling. The maximum and minimum roughness of the wall of grooves was 438 and 67nm, respectively

• 한국건축시공학회지
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• 제16권6호
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• pp.571-578
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• 2016

본 연구에서는 갯벌의 콘크리트용 혼화재 및 채움재로써의 활용 가능성에 대한 기초적 연구를 실시하였다. 먼저, 혼화재로서의 활용 가능성에 대해 화학 성분 분석을 실시한 결과 잠재수경성 및 포졸란 반응에 필요한 성분들이 함유되어있었지만 플라이애시 및 고로슬래그의 성분 분석 결과와 비교한 결과 성분 함유량이 소량으로 반응을 하기에는 부족한 양이었다. 또한, 물리적 실험 분석 결과 갯벌 치환율이 증가할수록 압축강도 및 인장강도가 감소하는 것으로 나타났다. 따라서 갯벌의 혼화재로서의 활용 가능성은 화학 성분분석에서 예상한 결과와 마찬가지로 낮은 것으로 나타났다. 채움재로서의 활용 가능성에 대한 시험을 실시한 결과 재령 28일 압축강도를 측정한 결과 갯벌의 채움재로서 활용가능성에 대한 분석을 통해 갯벌 치환율 10~30% 까지 벽돌의 압축강도 기준인 8MPa 이상의 강도를 발현하여 벽돌 등 2차 제품에 활용 가능할 것으로 판단되며, 향후 벽돌제작 등의 추가적인 실험이 필요할 것으로 판단된다. 플로우 시험결과에서는 갯벌 치환율이 증가할수록 플로우 값이 감소하는 것으로 나타났으며, 염화물 함유량 분석 결과를 통해 갯벌 자체의 염분 함유량이 많아 갯벌을 치환할 경우 철근 사용구조물에는 적용하기에는 부적합한 것으로 판단되며, 내장벽돌 등 철근을 사용하지 않는 제품에 활용이 가능할 것으로 판단된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권5호
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• pp.289-294
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• 2002

Cellulose production by Acetobacter pasteurianus was investigated in static culture using four bioreactors with silicone rubber membrane submerged in the medium. The shape of the membrane was flat sheet, flat sack, tube and cylindrical balloon. Production rate of cellulose as well as its yield on consumed glucose by the bacteria grown on the flat type membranes was approximately ten-fold greater than those on the non-flat ones in spite of the same membrane thickness. The membrane reactor using flat sacks of silicone rubber membrane as support of bacterial pellicle can supply greater ratio of surface to volume than a conventional liquid surface culture and is promising for industrial production of bacterial cellulose in large scale.

• 한국분무공학회지
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• 제13권1호
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• pp.9-15
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• 2008

This experimental study was carried out to examine the heat transfer characteristics of impinging air jet on a flat plate with a set of right angled triangle rods. Each right angled triangle rod in the array was positioned normal to the flow direction and parallel to the flat plate surface. The clearances from a right angled triangle rod to flat plate surface (C=1, 2 and 4 mm) and the distance from nozzle exit to flat plate (H=100 and 500 mm) were changed for the pitch between each right angled triangle rods (P=40 mm). As a result, heat transfer shows best performance at the clearance of C=1 mm, in case clearance changed, and the average heat transfer enhancement rate increased up to 47% compared to the result of a flat plate without a right angled triangle rod.