• 한국전산유체공학회지
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• 제20권1호
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• pp.77-83
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• 2015

Flow characteristics of synthetic jet based flow supplying devices have been computationally investigated for different device shapes. Jet momentum was produced by the volume change of a cavity by two piezoelectric-driven diaphragms. The devices have additional flow path compared with the original synthetic jet actuator, and these flow path changes the flow characteristics of synthetic jet actuator. Four non-dimensional parameters, which were functions of the shapes of the additional flow path, were considered as the most critical parameters in jet performance. Comparative studies were conducted to compare volume flow rate and jet velocity. Computed results were solved by 2-D incompressible Navier-Stokes solver with k-w SST turbulence model. Detailed computations revealed that the additional flow path diminishes suction strength of the synthetic jet actuator. In addition, the cross section area of the flow path has more influence over the jet performances than the length of the flow path. Based on the computational results, the synthetic jet based flow supplying devices could be improved by applying suitable shape of the flow path.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.1219-1223
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• 2005

This study was accomplished to confirm the possibility of supplying stream minimum flow from detention storage which was determined to reduce peak flows of flood within developing planned district. The results analyzed was summarized as follows; Firstly, Sin-gil district situated in Ansan city was selected, of which watershed area has $0.56km^2$. And detention storage was determined to $5,370m^3$ from analyzing flood volume by the SCS unit hydrograph method. Secondly, using Visual Basic ver 6.0, a detention storage water balance model was developed, in which simulation was based on conditioning storage inflow and outflow according to streamflow volume or rate state. And streamflow was simulated using the DAWAST model. Thirdly, detention operation scenarios were consisted of the combinations with inflow referencing streamflow of 5mm/day, 10mm/day and outflow referencing streamflow of 1mm/day, 2mm/day. The developed detention storage water balance model was operated to simulate daily water storages of detention sized on flood by scenarios. Stream minimum flows were able to be supplied during 209 days to 237 days per a year, total volume of stream minimum flows supplied for this period was analyzed to reach 27 to $55\% of yearly streamflow volume. If inflow criteria of streamflows to detention was considered to be established on a theoretical condition, it is expected to supply stream minimum flows of 20 to $30\% of yearly streamflow from stream to detention. Also to maximize function of supplying urban stream minimum flow from detention storages, sewage waters within developing planned district have to be treated and entered to detention inflow together with streamflows to enrich function of detention planned to reduce flood volumes.

• Journal of Biosystems Engineering
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• 제33권2호
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• pp.130-135
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• 2008

The purpose of this study was to develop a preprocessor for real-time portable quality evaluation system of milk. The preprocessor consisted of two flow pump to supply milk sample and reaction reagent at given volume, a fan to mix milk with reaction reagent, a thermoelectric device to maintain sample temperatures of $40^{\circ}C$, and I/O interface to control signals. The tests conducted with different level of flow rate of pump, fan speed, ambient temperature, and intial temperature of mixtures. To evaluate performance of the preprocessor, the supplied volumes, color changes, and temperatures were measured and analyzed. The results showed that the preprocessor could control supplying volumes, mixing, temperatures of samples automatically. The preprocessor showed good performance to be used for portable quality evaluation system of milk.

• 조명전기설비학회논문지
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• 제27권1호
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• pp.17-23
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• 2013

The BESS(Battery Energy Storage System) is an useful device for load leveling, but the high cost, installation space and safety issues are the main barriers for supplying it widely. The important factor in supplying BESS to customers successfully is the payback period. As most of the H/W cost factors are uncontrollable, the optimization of storage volume can be useful factor in improving payback period. In order to obtain optimized BESS volume, the load factor, demand ratio, peak shaving ratio, electric rates and benefits from DR participation of customer should be analyzed. In this paper, we could verify the peak cutting capability and cost effectiveness under the some proposed conditions and changing value of PCS and battery based on the customers data after volume optimization process was applied, and we can identified the saturation point of load factor and shortening of customer's payback period.

• 한국유기농업학회지
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• 제16권4호
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• pp.391-408
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• 2008

The overall focus of this study was to identify marketing and promotion strategies that can maintain and enhance environmentally friendly farm and organic production and processing activities. This is particularly important as the volume of environmentally friendly farm and organic produce that is generally available is increasing, and significant players, such as Organic Marketing Initiatives(OMI) and conventional marketing co-operatives, are becoming involved in the market. The rapid increase in production of environmentally friendly farm products and organic food is creating new and more complex challenges for marketing, from vegetable box schemes large co-operatives supplying the precise quality and volume required by supermarkets. A possible strategy for many farmers is to co-operate in regionally or nationally operating marketing initiatives. The main objective of any public relations(PR) activity should to enhance publicity and to improve an OMIs image. No promotion, no perception of OMI performance.

• 한국유체기계학회 논문집
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• 제11권5호
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• pp.50-56
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• 2008

Metal cutting operations involve generation of heat due to friction between the tool and the pieces. This heat needs to be carried away otherwise it creates white spots. To reduce this abnormal heat cutting fluid is used. Cutting fluid also has an important role in the lubrication of the cutting edges of machine tools and the pieces they are shaping, and in sluicing away the resulting swarf. As a cutting fluid, water is a great conductor of heat but is not stable at high temperatures, so to improve stability an emulsion type mixed fluid with water and oil is often used. It is pumped over the cutting site of cutting machines as a state of atomized water droplet coated with oil by using jet. In this paper, to develop cutting fluid supplying nozzle to obtain ultra thin oil film for coating water droplet, a numerical analysis of three dimensional mixed fluid Jet through multi-stage nozzle was carried out by using a finite volume method. Jet flow characteristics such as nozzle exit velocity, development of mixing region, re-entrance and jet intensity were analyzed. Detailed mixing process of fluids such as air, water and oil in the nozzle were also investigated. It is easy to understand complex flow pattern in multi-stage nozzle. Important flow Information for advance design of cutting fluid supplying nozzle was drawn.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.41-44
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• 1999

The main purpose of the UPS is to supply independent and stable power to connected equipment. In installing and operating the UPS system, songle module, three phase UPS in more benefit than multi module, songle phase UPS in the point of volume and cost. However, when supplying Rectifier with output power form three phase UPS, by connecting auto-transformer, occurred harmonic and ripple current makes output filter damaged and leads to nonlinear current coasted by unbalance load. Therefor, in this paper the aim of concentring compound-wound transformer and harmonic filter is supplying liner current by reducing harmonic and ripple current and improving unbalance in voltage and distortion in current wave.

• 원예과학기술지
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• 제16권1호
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• pp.25-26
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• 1998

본 연구는 정량펌프를 이용한 정확한 증산량 추정 시스템의 구축 및 측정된 증산량과 환경요인과의 관계를 분석하는 데 있다. 정량펌프에 의한 양액공급 및 증산량 추정 시스템은 매우 안정적인 특성을 나타냈으며, 증산량 추정을 위하여 재배 시스템에 설치한 정량펌프의 공급시간과 투입량과의 관계는 직선관계를 나타냈다. NFT 및 고형배지 시스템에서의 적산일사량과 증산량을 실측한 결과 증산량은 일사량에 직접적인 영향을 받고 있었으며, NFT는 상관계수 0.98. 고형배지는 상관계수 0.92의 높은 상관관계를 나타내었다. 따라서 정량펌프에 의한 증산량 추정은 양액급액 제어에 효율적인 방법이며, 이러한 방법을 사용하여 적산일사량에 의한 관수량 조절 및 비료투입량의 결정에 적용이 가능하다. 따라서, 측정된 적산일사량에 의하여 증산량 추정이 가능하기 때문에, 정량펌프에 의하여 필요 관수량을 정확한 공급할 수 있다.

• Journal of Korean Neurosurgical Society
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• 제40권6호
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• pp.423-427
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• 2006

Objective : Postoperative brain swelling after resection of olfactory groove meningiomas by bifrontal interhemispheric transbasal approach is a knotty subject. Pathogenesis and predictive factors were investigated to prevent the problem. Methods : Eighteen patients of olfactory groove meningiomas who had undergone surgery were enrolled and retrospectively analyzed using their clinical and radiological data. Bifrontal inter hemispheric transbasal approach was used in all patients. Magnetic resonance imaging and transfemoral cerebral angiography were available for investigation in 18 and 14 patients respectively. Postoperative clinical course, tumor volume, peritumoral edema, tumor supplying vessels, and venous drainage patterns were carefully investigated in relation to postoperative brain swelling. Results : Seven patients [39%] developed clinically overt brain swelling after surgery. Among them, 4 patients had to undergo decompression surgery. In three patients, attempted bone flap removal was done by way of prevention of increased intracranial pressure resulted from intractable brain swelling and two of them eventually developed brain swelling which could be recovered without sequellae. Abnormal frontal base venous channel observed in preoperative angiography was significant predictive factor for postoperative brain swelling [p=0.031]. However, tumor volume, peritumoral edema, and existence of pial tumor supplying vessels from anterior cerebral arteries were failed to show statistical significances. Conclusion : To prevent postoperative brain swelling in olfactory groove meningioma surgery, unilateral approach to preserve frontal base venous channels or temporal bone flap removal is recommended when it is indicated.

• 한국환경복원기술학회지
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• 제16권5호
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• pp.1-17
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• 2013

We researched the fauna restoration of 5 urban streams in Ulsan established as ecological streams by improving water quality and river environment. The fauna inhabitation were compared according to the conditions of geometrical feature such as river width, low-water channel width, ect and water quality, water volumn, inland and forceland. The Mugeo cheon has clearly shown the fauna restoration effects resulting from supplying sustainable maintenance water and wastewater treatments. In the Yaksa cheon, on the other hand, the restoration effects were low due to the inflow of wastewater and sledges in some part of stream ever though the improvement of water quality. The Yeocheon cheon was found to have disadvantage on the ecological inhabitations due to supplying the maintenance water with highly concentrated salinity. The fauna restoration effect of the Meongjeong cheon was low due to the inflow of wastewater to the down stream. Therefore by supplying the maintenance water and improving the connection to the Taehwa river at the estuary, better restoration effects could be observed. In the Cheokgwa cheon, which is almost a natural river, the ecological integrity of the fauna population has been maintained quite well. It was concluded that the project to transform urban streams into ecological streams should focus on not only keeping water volume and quality but also maintaining favorable conditions for the migration and settlement of animal species close to the natural state.