• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1999.11a
• /
• pp.31-34
• /
• 1999

기-고체간의 접촉효율이 높고, 층 내 전체에 걸쳐서 균일한 기-고의 접촉을 갖는 등 많은 장점이 있어 석탄연소로, 촉매반응기와 같은 여러 기-고 반응기에 적용이 확대되고 있는 순환유동층은 높은 유속에서 조업되므로 상승관내 고체입자들은 즉시 비산하게 된다. 따라서, 원활한 반응에 필요한 상승관내 적절한 고체체류량 유지를 위해 고체입자들 대부분은 싸이클론에서 포집 되어 고체재순환부에 의하여 상승관내로 재주입 된다.(중략)

• Aerospace Engineering and Technology
• /
• v.8 no.1
• /
• pp.197-206
• /
• 2009

To improve the aerodynamic efficiency of Smart Unmanned Aerial Vehicle (SUAV), vortex generators and flow fence are applied on the surface and the tip of wing. The initially applied vortex generator increased maximum lift coefficient and delayed the stall angle while it produced excessive increase in drag coefficient. It turns out reduction of the airplane's the lift/drag ratio. The new vortex generators with L-shape and two different height, 3mm and 5mm, were used to TR-S4 configuration to maintain the desired level of maximum lift coefficient and drag coefficient. Flow fence was also applied at the end of both wing tip to reduce the interaction between nacelle and wing when nacelle tilting angles are large enough and produce flow separation. To examine the effect of flow fence, flow visualization and force and moment measurements were done. The variation of the aerodynamic characteristics of SUAV after applying flow control devices are summarized.

• Journal of the Korean GEO-environmental Society
• /
• v.2 no.2
• /
• pp.41-50
• /
• 2001

In this study, for the stability analysis of marine embankment, the slope stability analysis and possibility of lateral movement with the marine embankment in ${\bigcirc}{\bigcirc}$harbor were carried out. In order to simulate the practical site condition, the expected maximum sea water level and maximum embankment height were assumed for these analyses. For the evaluation of soil properties, field test, laboratory test, and especially chemical composition analysis were performed for the this analysis. Based on these test results, the soil parameters were determined by applying ground improvement concept under columnar stabilized ground condition and also the effect of staged backfilling was considered under the dredged ground condition. For the optimal design, the stability analyses of embankment with changed height and unchanged height were performed under unimproved soil condition. The result showed that both cases were unstable not only with slope stability but also with lateral movement. Therefore, Deep Mortar Piling was applied for stability analysis and this result was safe. As the conclusion, the deep mortar piling method was suggested as reinforced foundation design for this site.

• Plant Journal
• /
• v.12 no.4
• /
• pp.44-50
• /
• 2016

To model the compression system with more integrity, the pipeline dynamic model was applied to the compression system model. To combine the pipeline dynamic model and the compression system model, appropriate boundary conditions were selected on each end of connecting pipe with compressor, plenum and throttle valve. Simulation result illustrate the effect of pipeline dynamic model on the stability of compression system.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.13 no.6
• /
• pp.48-55
• /
• 2009

The purpose of using Gas Generator Oxidizer On/Off Valve(GOV) is to control opening and closing of oxidizer mass flow. This paper describes analytical results of flow and structural properties for four different GOV models, using commercial software such as Fluent(Ver. 6.3.26) and NASTRAN(2005 r.2), PATRAN(2005 r.2). Analytical results show that GOVs could generate 2.3~3.8 kg/s of oxidizer mass flow rate and come up with 1.09~1.42 of safety factor.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.363-365
• /
• 2008

탄소나노튜브를 이용한 이미터 전계방출 면광원용 안정기를 제안한다. 안정기는 고전압 직류전압 부분과 양극의 펄스를 생성하는 부분으로 구성되어 있다. 탄소나노튜브를 이용한 전계방출 램프는 3가지의 전극 (애노드, 게이트, 캐소드)으로 구성되어 있는데, 애노드와 게이트 사이에는 고전압 직류가 공급되고 게이트와 캐소드 사이에는 양극의 펄스가 공급된다. 램프 및 안정기를 보호하기 위하여 과전류, 과전압, 과온도에 대한 보호 기능을 추가하였고, 실험을 통하여 제안된 방식이 탄소나노튜브 램프 구동을 위한 적합함을 검증하였다.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.937-938
• /
• 2006

본 연구는 광 출력이 조정이 가능한 UV Lamp용 안정기에 관한 연구이다. UV Lamp는 하수 종말 처리장의 하수 처리에 사용되고 있는데, 기존의 UV Lamp용 안정기는 처리되는 하수의 양과 관계없이 일정한 출력을 내는 방식으로 항상 일정의 전력을 소모하였다. 본 연구에서는 하수의 양에 따라 광 출력을 최대 출력의 50%까지 안정기에서 조정하는 방식으로 하수의 양이 적을 시에는 광 출력을 줄여 전력의 소모를 줄일 수 있고, 아울러 고가의 UV Lamp의 수명을 연장할 수 있어 UV Lamp 및 교체 비용의 감소를 기대할 수 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2005.11a
• /
• pp.450-454
• /
• 2005

A numerical analysis is performed to analyze the reacting flow-field of an axisymetric coaxial ramjet combustor. Two dimensional Navier-Stokes equation with low Reynolds number $k-\varepsilon$ turbulence model is utilized and finite-rate chemistry model is adopted. Eddy dissipation model is applied for a modeling of turbulent combustion. Two different types of combustors (combustor with a suddenly expanded dump and combustor with wedge-shaped flame holders) are compared in a view point of flame stabilizing.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.1
• /
• pp.246-253
• /
• 2013

This paper addresses the technology of active flow control for stabilizing a flow field. In order for flow field modeling from the control point of view, the huge-data set from CFD(computational fluid dynamics) are reduced by using a POD(Proper Orthogonal Decomposition) method. And then the flow field is expressed with dynamic equation by low-order modelling approach based on the time and frequency domain analysis. A neural network flow estimator from the pressure information measured on the surface is designed for the estimation of the flow state in the space. The closed-loop system is constructed with feedback flow controller for stabilizing the vortices on the flow field.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.12
• /
• pp.1218-1224
• /
• 2008

A liquid culture of yeast "Candida tropicalis" was used in a fluidized bioreactor to achieve high removal efficiencies of volatile organic compounds (VOCs). In this study, granular activated carbon (GAC) was used as a fluidized material to improve adsorptive capacity as well as mass transfer of gaseous toluene, the model VOC. The GAC fluidized bioreactor demonstrated toluene removal efficiencies ranging from 50 to 80%, when inlet toluene loading varied in a range between 13.1 and 37.4 g/m$^3$-hr. The maximum elimination capacity determined in the GAC fluidized bioreactor was 172 g/m$^3$-hr at a toluene loading of 291 g/m$^3$-hr. Transient loading experiments revealed that the removal efficiency was remained unchanged during an increased loading period, and toluene introduced to the bioreactor was first absorbed to GAC and then slowly desorbed and became available to the yeast culture. Hence the fluidized GAC helped to achieve an improved mass transfer between the gas and liquid phases, resulting in high toluene removal capacity. Consequently, the GAC fluidized bioreactor using C. tropicalis can be successfully applied for the removal of VOCs, and is a feasible alternative over conventional processes such as packed-bed biofilters.