• 한국정밀공학회지
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• 제24권11호
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• pp.101-107
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• 2007

Jettability analysis using one-dimensional(1D) lumped parameter model has been investigated to design the industrial inkjet head with proper drop velocity and drop volume. By simplifying the inkjet head system into an equivalent electrical circuit, lumped model has been developed. Performance of the lumped model is verified by the comparison between measured results of droplet velocity and ejection volume and predicted value. Also, the jetting performance of an inkjet head is characterized by varying the design parameter and driving condition. As a result, simulation results shows good agreement with the experimentally measured value. The developed lumped model enables to easily understand the effect of dimension change and predict the jetting performance.

• 설비공학논문집
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• 제12권7호
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• pp.632-641
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• 2000

The present study concerns the simulation of supply-air control in a variable air volume (VAV) system. A stratified lumped thermal model (multi-zone model) is suggested to predict local thermal response of an air-conditioned space. The effects of various thermal parameters such as the cooling system capacity, the thermal mass of air-conditioned space, the time delay of thermal effect, and the building envelope heat transmission are investigated in detail. Further, the influence of control parameters, PI control factor and the sensor location on a VAV system is quantitatively delineated. The results obtained show that the previous homogeneous lumped thermal model (1-zone model) may predict a significantly different thermal response in the air-conditioned space according to the sensor location.

• 대한수학회지
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• 제43권4호
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• pp.885-897
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• 2006

A new mathematical model of pumping heart coupled to lumped compartments of blood circulation is presented. This lumped pulsatile cardiovascular model consists of eight compartments of the body that include pumping heart, the systemic circulation, and the pulmonary circulation. The governing equations for the pressure and volume in each vascular compartment are derived from the following equations: Ohm's law, conservation of volume, and the definition of compliances. The pumping heart is modeled by the time-dependent linear curves of compliances in the heart. We show that the numerical results in normal case are in agreement with corresponding data found in the literature. We extend the developed lumped model of circulation in normal case into a specific model for arrhythmia. These models provide valuable tools in examining and understanding cardiovascular diseases.

• 대한의용생체공학회:의공학회지
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• 제24권4호
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• pp.329-337
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• 2003

선천적 혹은 후천적인 이유로 인하여 인체 특정 부위의 정맥과 동맥이 서로 관통하여 동맥계의 혈류가 말초 혈관계를 우회하여 정맥계로 흐르게 되는 동정맥루는 인체 심혈관계의 혈류 역학적 거동에 큰 영향을 미치게 된다. 본 연구에서는 lumped parameter 모델을 기반으로 하는 수치 해석 방법을 사용하여 우측 하지에 위치한 급성 동정맥루가 전체 심혈관계에 미치는 영향을 해석적으로 고찰하였다. 이를 위하여 동정맥루가 포함된 인체 심혈관계를 전기 회로 상사계로 구성하였으며. 부위별 혈압과 관련된 상미분 연립 방정식을 4차의 Runge-Kutta방법으로 풀어서 시간에 따른 혈류 역학적 변수들을 구하였다 이때 급성 동정맥루의 생성에 따른 혈류 역학적 보상작용을 분석하기 위하여 arterial baroreflex 제어계를 모델에 포함하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.143-150
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• 2000

A physical lumped parameter model is proposed for the time domain analysis of dam-reservoir system. The exact solution of transmitting boundary is derived for a semi-infinite 2-D reservoir of constant depth. The characteristics of the solution are examined in both frequency and the domains. Mass and damping coefficient are obtained from asymptotic behavior of the frequency domain solution. Further refinement to the lumped model is made by approximating the kernel function of the convolution integral in the exact solution. Finally a new physical lumped parameter model is proposed that consists of two masses, a spring and two dampers for each mode. It is demonstrated that new lumped parameter model of transmitting boundary can give excellent results.

• 한국산업융합학회 논문집
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• 제12권1호
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• pp.27-33
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• 2009

In this paper, a computational analysis using a lumped system model is performed to investigate the hemodynamics of coronary circulation under the operation of T-PLS relevant to the cardiac arrest cases. The coronary circulation system is assumed to be comprised of three compartments: coronary arteries, coronary capillaries, and coronary veins. The effect of myocardial muscle contraction or relaxation is represented by temporal variations in the bias pressure. To verify the present method, we analyzed the coronary circulation for normal case and then compared the results with the existing data. Numerical results on the cardiac arrest model showed that T-PLS can increase LAD flow significantly.

• 한국소음진동공학회논문집
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• 제13권5호
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• pp.393-399
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• 2003

Hydraulic mounts show strong1y frequency-dependent stiffness and damping characteristics in low frequency range, which result from so called inertia track dynamics. A lumped mass has been incorporated in several mechanical models of the literature to take the inertia effect of the fluid in the track into consideration. Although complex s%illness by the mechanical model showed good agreements with the measured values, there exists a critical pitfall. In this paper, the shortcomings of mechanical models with lumped mass for hydraulic founts are clearly identified by illustrating actual measurements of the stiffness parameters for a hydraulic mount. It is conclusively discussed that the inertia effect of the fluid flow through the circular track is significant but latent. As an alternative to the mechanical model, a hydraulic model is claimed to be used for further dynamic analysis of engine/mount system or whole car system.

• 한국지진공학회논문집
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• 제5권4호
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• pp.27-38
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• 2001

반무한 호소의 동적 모델링을 위한 역학적 집중변수모델을 제안하였다. 깊이가 일정한 2차원 반무한 호소의 전달경계의 정해를 구하였다. 정해의 거동특성을 주파수 영역과 시간 영역에서 조사하였다. 고유진동수와 합성곱 적분의 핵함수인 베셀 함수의 모양 등과 같은 해의 주요 특성이 변하지 않도록 질량, 감쇠기, 스프링 계수를 구한다. 최종 집중 변수 모델은 각각의 고유값에 대해 2개의 질량, 1개의 스프링, 2개의 감쇠기로 구성된다. 적용 예제를 통하여 새로운 집중변수모델이 댐-호소계의 시간 영역 해석에 효율적으로 사용될 수 있음을 확인하였다.

• 제어로봇시스템학회논문지
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• 제10권12호
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• pp.1181-1188
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• 2004

This paper reviews the main aspects of cardiovascular system dynamics with emphasis on modeling hemodynamic characteristics using a lumped parameter approach. Methodological and physiological aspects of the circulation dynamics are summarized with the help of existing mathematical models: The main characteristics of the hemodynamic elements, such as the heart and arterial and venous systems, are first described. Lumped models of micro-circulation and pulmonary circulation are introduced. We also discuss the feedback control of cardiovascular system. The control pathways that participate in feedback mechanisms (baroreceptors and cardiopulmonary receptors) are described to explain the interaction between hemodynamics and autonomic nerve control in the circulation. Based on a set-point model, the computational aspects of reflex control are explained. In final chapter we present the present research trend in this field and discuss the future studies of cardiovascular system modeling.

• 융복합기술연구소 논문집
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• 제1권1호
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• pp.41-47
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• 2011

With the world-wide demand on the emission minimization, the needs on the diesel aftertreatment devices with high efficiency are also increasing. In order to effectively develop or design a high-performance diesel particulate filter, a clear understanding on the deposition and regeneration mechanism is required. In the present study, a theory on the lumped parameter model for wall-flow type diesel particulate filters is described focusing on the deposition efficiency, pressure drop inside the filter. The fourth order explicit Runge-Kutta method is utilized for the mass flow rate computation. Engine operation modes with controlled and uncontrolled regeneration options are selected. The computational lumped parameter model is validated by comparing the computed results with the measured data.