• 대한기계학회논문집
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• 제1권4호
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• pp.171-181
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• 1977

This paper is aiming at calculating NOx concentration, which is one of the harmhul components of emission from the gasoline engine, formed in the combustor through the presess of combustion. Instantaneous temperature and concentration of each components for each division can be determined by the solution of simulatneous equation of reaction equation and equation of energy conservation, inputting the estimated temperature with a considerably wide rage of temperature. After determining instantaneous temperature and instantanous concentration of each components, the nonequilibrium calculation is performed based on the reaction kinetics in order to determine NOx concentration. To summarize the result abtained from the above method ;through the passage of NO concentration, NO concentration is the highest in the first division and it is gradually decreasing through the following divisions In the final division, NO concentation is the lowest.

• 전력전자학회논문지
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• 제17권1호
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• pp.41-47
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• 2012

This paper proposes a calculation of compensation current using phase shift to eliminate ripple components of instantaneous active power under unbalanced or non-linear loads condition. The proposed phase shift method instead of existing method(LPF; Low Pass Filter) to remove ripple components and this proposed method improves performances of transient and steady state response. To compare proposed method with existing method, experiments have been done for calculating an average active power at load side. Their results show that transient response and steady state response of proposed method is improved.

• 한국항공운항학회지
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• 제31권4호
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• pp.7-18
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• 2023

The continuous increase in air traffic emphasizes the importance of capacity calculation. Research on the calculation method of Terminal Control Area (TMA) capacity has been treated as a partial aspect of the airspace sector capacity or has been limitedly studied. This study aims to propose a mathematical model for calculating TMA capacity, taking into account the Standard Terminal Arrival Route (STAR), separation standards, TMA entry speed, and runway threshold passing speed. The proposed model has the advantage of being able to calculate the instantaneous arrival capacity, which has not been noted in previous studies, along with the throughput. Additionally, it is meaningful as the model can easily calculate the arrival capacity of the TMA considering airport construction, runway expansion, or new procedures.

• 한국공작기계학회논문집
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• 제11권4호
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• pp.34-43
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• 2002

The purpose of this paper is to further extend the theoretical understanding of the dynamic end milling process and to derive a computational model to predict the milling force components. A comparative assessment of different cutting force models is performed to demonstrate that the instantaneous shear plane based formulation is physically sound and offers the best agreement with experimental results. The procedure f3r the calculation of the model parameters used in the cutting force model, based on experimental data, has been presented. The validity of the proposed computational model has been experimentally verified through a series of cutting tests.

• 한국산업정보학회논문지
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• 제21권3호
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• pp.1-6
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• 2016

LMS 알고리즘에서, 시간영역의 적응알고리즘은 입력신호의 고유치 분포 폭이 넓게 분포되면, 수렴속도가 느려지기 때문에 가변 스텝 사이즈가 많이 사용된다. 그러나 이 경우 많은 계산량이 필요하다. 본 논문에서는 시간영역의 적응 알고리즘을 변환영역에서 수행한다. 그리고 수렴성능 향상과 계산량을 줄이기 위하여 평균오차의 순시 절대 값을 exponential 함수에 적용한 새로운 알고리즘을 제안한다. 그리고 시스템 제너레이터를 이용하여 시뮬레이션 및 검증을 하였다. 그 결과 순시 절대 값에 비례하여 변화하는 가변스텝사이즈의 적응알고리즘이 기존의 알고리즘과 비교하여 보다 안정되고 성능이 우수함을 입증하였다.

• 융합신호처리학회논문지
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• 제14권2호
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• pp.95-98
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• 2013

LMS(Least Mean Square)알고리즘은 강인성, 높은 추적성, 구현의 단순성 때문에 아직도 많이 사용되는 알고리즘이다. 하지만, LMS알고리즘은 비균일적인 수렴율과 EMSE(Excess mean square error)사이에 trade-off를 가진다. 이러한 단점을 극복하기 위해, 많은 가변 스텝 사이즈 알고리즘이 연구되고 있다. 빠른 수렴속도를 위하여 복잡한 가변스텝 방식을 사용 하는데 많은 계산량을 필요로 한다. IGC(Instantaneous Gain Control) 알고리즘은 원신호와 잡음신호의 순시이득값을 사용하여 계산량은 줄이고 높은 성능을 유지한다. 하지만 IGC 알고리즘은 이득값 계산시 log함수에 의해 실행시간이 오래 걸리는 단점을 가진다. 제안하는 변형 IGC알고리즘은 실행시간을 지연하는 log 함수를 제거하여, 실시간 소음제거 처리에 맞게 변형하여 성능 개선을 이룰 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1480-1482
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• 2005

The major causes of power quality deterioration are harmonic current through semiconductor switching device, due to use of nonlinear loads such as diodes rectifier or thyristor rectifiers. In response to this concerns, this paper presents a new control method of single-phase active power filter(APF) for the compensation of harmonic current components in nonlinear loads. In order to make the complex calculation to be possible, the single-phase system that has two phases was made by constructing a imaginary second-phase giving time delay to load currents. In the conventional method, a imaginary-phase lagged to the load current T/4(here T is the fundamental cycle) was made. But in this proposed method, the new signal, which has the delayed phase through the filter, using the phase-delay property of low-pass filter, was used as the second phase. As this control method is applied to the system of single phase, an instantaneous calculation was done rather by using the rotating reference frames that synchronizes with source-frequency than by applying instantaneous reactive power theory that uses the conventional fixed reference frames.

• 전력전자학회논문지
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• 제13권3호
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• pp.179-185
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• 2008

본 논문에서는 SRM의 토크리플 억제를 위하여 PWM(Pulse width modulation)과 직접토크제어(DITC, Direct Instantaneous Torque Control) 방식의 결합에 의한 제어방식을 제안하였다. 기존의 직접토크제어와 달리, 제안된 방식은 한 샘플링 구간 내에서 하나 또는 두 개의 스위칭 모드로 동작하며, 스위칭 패턴의 폭은 토크 오차와 직접 토크제어 방식의 제어규칙에 따라 제어된다. 또한 실제 스위치의 제어폭이 토크 오차에 따라 가변적으로 제어됨으로써, 같은 샘플링 주기에서 기존의 직접토크제어 방식에 비하여 토크리플을 크게 억제할 수 있으며, 토크 연산의 샘플링 주기를 크게 할 수도 있는 장점이 있다. 간단한 제어규칙과 PWM 듀티비의 계산으로 복잡한 연산이 요구되지 않으므로 저가의 마이크로 프로세서에 의해 구현이 가능하다. 제안된 방식은 컴퓨터 시뮬레이션과 실험을 통하여 검증하였다.

• 대한기계학회논문집
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• 제16권9호
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• pp.1669-1680
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• 1992

본 연구에서는 볼 엔드밀 가공에서 공구계의 처짐을 고려한 절삭력과 처짐을 예측하고, 처짐의 예측으로 가공 정밀도를 향상시키는 이송 속도와 헬릭스 각의 선정 에 대해서 고찰한다.

• 설비공학논문집
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• 제17권12호
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• pp.1161-1168
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• 2005

A Multi-Sectional 3D-PTV algorithm was developed to reduce the calculation time of the conventional GA-3D-PTV. The hardware system of the constructed 3D-PTV system consists of two high-speed cameras ($1,024\times1,018$ pixels, 60 fps), a metal halogen lamp (400W) and a host computer. The sphere(D=30mm) is suspended in a circulating water channel $(300mm\times300mm\times1,200m)$ and Reynolds number is 1,130. About 5,000 instantaneous three-dimensional velocity vectors have been obtained by the constructed 3D-PTV system. Turbulent properties such as turbulent intensity, Reynolds stress and turbulent kinetic energy were obtained. An eigenvalue analysis was carried out using the obtained instantaneous 3D velocity vectors to get the topological relations of the asymptotically stable critical point. Two structured shells, inner shell and outer shell, were found in the sphere wake and their motions were clarified by the measured data.