• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.444-445
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• 2006

Flying trajectories of fine particles within a size range of $10{\sim}60{\mu}m$ were studied during centrifugal atomizing processes. A FORTRAN program was written by using increment method. Calculation results revealed that the drag force might reach very high value of 522-7800 g for fine powder of $10{\sim}60{\mu}m$. Flying distance in horizontal direction could be shortened if the particles fly obliquely due to the huge drug force. On the other hand, very fine powder could be projected to far distances when the atmosphere flow velocity is much stronger. Fortunately such particles could be contracted within a cylinder closed to the atomizer when the atmosphere flow was weaken or retained in a limited diameter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.512-513
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• 2012

The electric motor is essential to drive turbo machinery. In order to overcome the speed limitations of general motors, the inverter is used to perform high speed to tens of rpm. The high speed drives are widely used in many applications such as turbo blower, turbo centrifugal compressors, and pump using air bearing technique. Starting of high speed motor can cause step out, stall, oscillation of motor because the phase inductance is much smaller than that of ordinary motor. This paper studied on the starting characteristic of variable speed centrifugal chiller considering high speed motor characteristics. Finally, the superiority of the inverter is verified by experimental results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.82-87
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• 2000

During the operation, fatigue failures and cracks of duct plate due to excessive duct vibration occurred in the fan-duct systems of fossil fueled boilers. We measured static pressure variation(pressure pulsation) in the outlet, and also measured vibration at the outlet duct of a centrifugal fan. It was found that strong pressure pulsation caused by the inlet vortex occurred in inlet vane of centrifugal fan in the middle range of vane opening. Thus, excessive duct vibration is caused by strong pressure pulsation. In this paper, it is shown that the frequency and amplitude of pressure pulsation depend mainly on vane opening and are compared with duct vibration. Also, effective solution for reducing pressure pulsation and vibration are presented.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.119-124
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• 2000

The 3-stage centrifugal compressor is used in order to measure the noise spectra of compressor, and analyze the results. Two cases are investigated for compressor noise components. Case I includes total system such as compressor, inter-cooler, motor, and Case II excludes cooling system. BPF tonal noise is important in compressor, and cooling system including inter-cooler contributes to broadband noise. Also, motor, gear box, and motor cooling fan are the second contributions to total compressor noise. Centrifugal compressor flow-field is calculated using two-dimensional grid and Navier-Stokes equations. Static pressure increases, and total pressure decreases, as air passes through the compressor components.

• 한국기계기술학회지
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• 제13권3호
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• pp.49-55
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• 2011

For the purpose of the enhancement of the air conditioner performance and fuel effciency, several cases of centrifugal impeller for passenger car air conditioner have been numerically analyzed by changing central angle of blades and length of outlet for shape optimization of the impeller. Commercial CFD program Fluent 6.3.26 has been used to compute velocity, temperature, pressure and turbulence intensity that can lead numerous results. The central angles of two blades and three cases of outlet length led 4~12% and 3.5~6.4% differences of velocity and flow rate, respectively. The velocity distribution near the blade surface was axisymmetric and had a maximum value of 22.19 m/s and velocity of the vertical direction of the impeller showed linear increase with horizontal direction. At case 3 of oultet length, there existed a a minimum pressure value of -133320 Pa.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.751-755
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• 2008

During the rapid startup transient of a centrifugal pump, in order to investigate its transient characteristics, the torque equations are deduced. Based on these equations, numerical simulation is carried out with the Large Eddy Simulation(LES) method and UDFs(User Defined Functions) are applied during the simulation. Comparison between simulation and experiment results of pump heads and rotational speed shows that they are in good agreement, indicating that the dynamic characteristics of this pump can be predicted accurate comparatively through simulation with LES method during its startup process.

• 한국음향학회지
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• 제42권6호
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• pp.519-528
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• 2023

본 논문에서는 식기 세척기 내 원심펌프를 대상으로 수치적/실험적 연구를 통해 최적 설계를 수행하였으며 유량 및 소음 성능을 개선하고자 하였다. 먼저 대상 원심펌프의 특성을 실험적으로 분석하기 위해 펌프 성능시험기를 통한 유량 실험과 반 무향실에서의 소음 실험을 진행하였다. 원심펌프 회전에 따른 내부 유동 및 유동 소음 성능을 수치적으로 모사하기 위해 전산유체역학 기반의 Reynolds Averaged Navier-Stokes(RANS) 방정식과 Ffowcs Williams and Hawkings 방정식을 지배 방정식으로 수치해석을 수행하였다. 실험 결과와의 비교를 통해 수치 기법의 유효성을 검증하였으며, 검증된 수치 기법을 활용하여 원심펌프 내 임펠러 형상에 대한 최적 설계를 수행하였다. 수치 기법의 활용을 통해 최적 설계된 임펠러의 개선된 유량 성능을 수치적으로 확인하였으며, 유동장 분석을 통해 임펠러 형상 각도 변화에 따른 유동 특성 변화 및 개선을 확인하였다. 또한, 시제품 제작 및 실험을 통해 개선 유량 성능을 검증하였으며, 팬 법칙에 의거하여 동일 유량에서 소음 수준이 감소함을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.818-824
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• 2012

When the Langer modification is applied to Coulomb potential, the standard WKB quantization yields an exact energy spectrum for the potential. This Langer modification has been known to be related to the centrifugal term appearing in Coulomb potential. But we find that a similar modification exists for all translationally shape invariant potentials without referring to the centrifugal term. The characteristic shape of the potentials accounts for the generalized version of Langer modification that makes the WKB quantization valid for all translationally shape invariant potentials.

• 시스템엔지니어링워크숍
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• 통권4호
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• pp.65-69
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• 2004

Abstract Tilting train has been developed to increase the oprational speed of the trains on conventional lines which have many curves. This train are tilted at curves to compensate for unbalanced carbody centrifugal acceleration to a greater extent than compensation produced by the track cant, so that passengers do not feel centrifugal acceleration and thus trains can run at higher speed at curves. This paper developed PDM(product data management) to make a system engineering of TTX(Tilting Train eXpress) with maximum operation speed 180 km/h.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.110.1-110.1
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• 2005