• 대기
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• 제20권4호
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• pp.451-466
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• 2010

This edition has continued since 2006 tropical cyclone season our effort to provide standard tropical cyclone summaries by the western North Pacific basin and detailed reviews of operationally or meteorologically significant tropical cyclones to document significant challenges and shortfalls in the tropical cyclone warning system to serve as a focal point for research and development efforts. The tropical cyclone season of 2009 in the western North Pacific basin is summarized and the main characteristics of general atmospheric circulation are described. Also, the official track and intensity forecasts of these cyclones are verified. The total number is less than 59-year (1951~2009) average frequency of 26.4. The 2009 western North Pacific season was an inactive one, in which 22 tropical storms generated. Of these, 13 TCs reached typhoon (TY) intensity, while the rest 9 TCs only reached severe tropical storm (STS) and tropical storm (TS) intensity - three STS and six TS storms. On average of 22 TCs in 2009, the Korea Meteorological Administration official track forecast error for 48 hours was 219 km. There was a big challenge for individual cyclones such as 0902 CHAN-HOM, 0909 ETAU, and 0920 LUPIT resulting in significant forecast error, with both intricate tracks and irregular moving speed. There was no tropical cyclone causing significant direct impact to the country. The tropical cyclone season in 2009 began in May with the formation of KUJIRA (0901). In September and October, ten TSs formed in the western North Pacific in response to enhanced convective activity. On the other hand, the TC activity was very weak from June to July. It is found that the unusual anti-cyclonic circulation in the lower level and weak convection near the Philippines are dominant during summertime. The convection and atmospheric circulation in the western North Pacific contributed unfavorable condition for TC activity in the 2009 summertime. Year 2009 has continued the below normal condition since mid 1990s which is apparent in the decadal variability in TC activity.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.644-649
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• 2000

A new cyclone system for the vacuum cleaner to collect dusts has been studied experimentally and numerically to meet the constant suction power, hygienic exhaust and a reduction of maintenance cost. The cyclone system of the vacuum cleaner consists of twin cyclones for improving dust collection efficiency. The first. cyclone catches large dust particles and the second one having two separated flows to decrease pressure drop collects small dust particles. The optimal design factors such as dust collection efficiency, pressure drop, and cut-size are investigated from the experimental results by the Taguchi method. Cyclone cleaner systems designed in this study has a good Performance taking into account the dust collection efficiency of 93% and the cut-size of $1.6{\mu}m$ in mass median diameter at the flow rate of 1 CMM. The cyclone vacuum cleaner showed the potential to be an effective method to collect dusts generated in the household.

• 한국지능시스템학회논문지
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• 제24권5호
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• pp.512-517
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• 2014

본 연구는 선박의 외벽 유지보수를 위한 외벽 연마장비에 장착되는 먼지 집진장치에 적용하기 위한 사이클론 집진방식의 연마기 제작을 위한 사이클론 분리기 설계를 위하여 최적의 설계조건을 도출하고자 유동해석 기법을 적용한 사이클론 연마장비의 집진장치를 소개하고자 한다. 제작된 연마장비의 집진을 위한 접선유입 사이클론의 압력 강하와 입자 수집 능률은 기 연구된 수학적 모델을 적용하여 계산하였다. 종래 공기필터를 가진 사이클론의 계산 결과의 비교는 접선 유입 사이클론이 저압 드롭과 높은 입자 수집능률을 시뮬레이션을 통한 검증과 시작품을 제시하였다. 사이클론은 원통형 장치 내에 분진을 함유하는 기체를 장치내벽에 접선방향으로 유입시켜 유입분진에 선회운동을 부여함으로써 분진입자에 작용하는 원심력에 의하여 가스중의 입자를 분리 포집하는 집진장치로써 연마장비의 집진장치로 응용하고자 본 연구를 진행하여 진행중인 메커니즘과 유체흐름에 대한 기본적인 유체흐름에 따른 사이클론의 규격 파라미터에 따른 유동해석 결과를 제시하였다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.546-550
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• 2008

In this study, 3-dimensional Computational Fluid Dynamics (CFD) analysis was induced to simulate air flow and particle motion in the axial flow cyclone separator. The commercialized CFD code FLUENT was used to visualize pressure drop and particle collection efficiency inside the cyclone. We simulated 4 cyclone models with different shape of vane, such as turning angle or shape of cross section. For the air flow simulation, we calculated the flow field using standard ${\kappa}-{\varepsilon}$ turbulence viscous model. Each model was simulated with different inlet or outlet boundary conditions. Our major concern for the flow filed simulation was pressure drop across the cyclone. For the particle trajectory simulation, we adopted Euler-Lagrangian approach to track particle motion from inlet to outlet of the cyclone. Particle collection efficiencies of various conditions are calculated by number based collection efficiency. The result showed that the rotation angle of the vane plays major roll to the pressure drop. But the smaller rotation angle of vane causes particle collection efficiency difference with different inlet position.

• Ocean Systems Engineering
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• 제10권2호
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• pp.181-199
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• 2020

Cyclone Heat Potential (CHP) is an essential parameter for accurate prediction of the intensity of tropical cyclones. The variability of the heat storage in the near-surface layers and the vertical stratification near the surface due to large fresh water inputs create challenges in predicting the intraseasonal and interannual evolution of monsoons and tropical cyclones in the Bay of Bengal. This paper for the first time presents the D26- referenced cyclone heat potential observed in the Bay of Bengal during the period 2012-17 based on the in-situ data collected from 5.5 million demanding offshore instrument-hours of operation in the Ocean Moored Buoy Network for Northern Indian Ocean (OMNI) buoy network by the National Institute of Ocean Technology. It is observed that the CHP in the Bay of Bengal varied from 0-220 kJ/㎠ during various seasons. From the moored buoy observations, a CHP of ~ 90 kJ/㎠ with the D26 isotherm of minimum 100m is favorable for the intensification of the post-monsoon tropical cyclones. The responses of the D26 thermal structure during major tropical cyclone events in the Bay of Bengal are also presented.

• Journal of Biosystems Engineering
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• 제24권6호
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• pp.487-492
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• 1999

One of effective utilization method of rice husk is to utilize it as culture material by carbonizing the rice husk. As a second part of a series to investigate the effective and continuous production of carbonized rice husk by a cyclone combustor, a non-slagging vertical cyclone combustor without vortex collector pocket was introduced. Isothermal and mixed firing with LPG and rice husk were undertaken in order to characterize the system. Inert rice husk was used during the isothermal test to find mass of rice husk collected. It was impossible to ignite rice husk itself over the experimental conditions considered in this experiment. Cyclone combustor was operated at temperatures of 1,273~1,473K. Detailed combustion data were obtained from a pilot unit with the air flow rate of 70m$^3$/h and rice husk feed of 2kg. The equivalence ratio ranged from 0.66 to 3.48. The auxiliary gas flow rate was varied from 3.22 to 12.86$\ell$/min. The weight reduction, pH and particle size distribution of carbonized rice husk were measured to evaluate the quality of carbonized rice husk. An analysis of exhaust gas emission was conducted to characterize the combustor. The required carbonized rice husk could be obtained at equivalence ratio of 1.68~2.17, combustor temperature of 1,273~1,373K and auxiliary gas flow rate of 3.22~6.43$\ell$/min. A method to reduce CO emissions should be employed.

• 에너지공학
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• 제13권2호
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• pp.112-117
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• 2004

휘발성 유기물질은 도장공정, 염색, 건조공정 등 화학공정에서 발생하는 저발열량 가스이다 VOCs의 특징은 발열량이 150kcal/㎥ 이하이며 착화를 위한 활성화 에너지가 높고 발생 에너지가 낮다는 것이다. 따라서 연소 안정성은 낮아지고 처리공정은 고에너지 소비공정이 된다. Cyclone연소시스템은 연소기 내에 강한 선회 유동을 만들어서 에너지를 순환시켜 활성화에너지를 낮추어주고 열밀도가 높아 일반적인 swirl 연소 시스템에 비해 고온의 연소온도를 유지할 수 있으며 혼합성을 향상시킨다 본 논문에서는 휘발성 유기물질의 열산화를 위해 최적의 cyclone 연소시스템을 개발하는 것을 목적으로 수행되었으며 특별히 설계된 연소기에서 연소온도와 배가스 조성에 미치는 swirl number의 영향을 정립하였다.

• 한국대기환경학회지
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• 제33권5호
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• pp.515-520
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• 2017

$PM_{2.5}$ concentrations were measured using a cyclone, impactor (the U.S. Environmental Protection Agency well impactor ninety-six, WINS) and optical particle counter (OPC) at a campus site located in Yongin for the period August 2014 through March 2017. The concentrations from cyclone (Y) were generally higher than those from impactor(X); the best-fit line was Y=1.22X+5.64. The ratios of $PM_{2.5}/PM_{10}$ ranged from 0.61 to 0.66 when $PM_{2.5}$ concentrations from cyclones in selected studies were converted into those from impactors using a regression equation in this study. The slope of the best-fit line between OPC and impactor was close to 1 at 0.95, while that between OPC and cyclone was 0.72. After sampling, the flow rate in the low-volume air sampler with cyclone decreased by 3% on average, which did not have a significant effect on measured concentrations.

• 한국대기환경학회지
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• 제18권5호
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• pp.401-410
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• 2002

Concerns for energy conservation, environmental pollution, and the fact that organic wastes account for a major portion of our waste materials, have created the interest of biogas, which usually contains about 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and other gases, including ammonia, hydrogen sulfide, mercaptans and other noxious gases. Cyclone combustors are used for homing a wide range of fuels such as low calorific value gas, waste water, sludge. coal, etc. The 3-dimensional swirling flow, combustion and emission in a tangential inlet cyclone incinerator under different inlet conditions are simulated using a standard k-s turbulence model and ESCRS (Extended Simple Chemically-Reacting System) model. The commercial code Phoenics Ver.3.4 was used for the present work. The main parameters considered in this work are inlet velocity and air to fuel ratio. The results showed that the change of operating conditions had an influence on the shape and size of recirculation zones, mixture fraction and axial velocity which are important factors for combustion efficiency and emission behavior. The application of this kind of computer program seams to be promising as a potential tool for the optimum design of a cyclone combustor with low emission.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_2호
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• pp.89-95
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• 2001

The solidification and leaching characteristics of cyclone ash collected from an industrial incineration plant were investigated. Cement and calcium hydroxide were used as the solidifying materials. The leaching characteristics of the solidified cyclone ash were found to vary depending on both the quantitative and the qualitative aspects of the solidifying materials. Except for copper and lead, all the heavy metal ions in the leachate of the solidified material composed of 10~20 % cement or 10~20 % calcium hydroxide were found to be within their standard limit. Moreover, all the heavy metal ions were also observed to be within satisfactory limits in the leachate obtained from the solidified material composed of 30 % cement or 30 % calcium hydroxide. Therefore, to satisfy the standard compressive intensity and permissible limits of heavy metal ions leached from solidified material, it would appear that a 30 % proportion of either additive in the solidification product can meet the required standard for the leachate. The cost of solidifying cyclone ash per ton for ash-30 % cement and ash-30 % lime was calculated as 26,750 and 26,070 won, respectively. Accordingly, significant reduction in the waste toxicity and mobility as well as an improvement in the engineering properties of the solidified products were successfully achieved.