• 한국대기환경학회지
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• 제17권2호
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• pp.223-231
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• 2001

In order to provide some insights into the influence of electric field, gas composition, and gas temperature on electron energy distribution and electron transport characteristics, the Boltzmann equation was solved by using cross section data for electron collisions, Critical electric fields for the corona development in dry air and flue gas are 150 and 80 Td, respectively. It was seen that the decrease of critical electric field in flue gas is mainly caused by the $H_2O$ addition through the comparison of ionization and attachment coefficients of gas components. Increase of $O_2$, $H_2O$, and $CO_2$ contents in gas affected discharge characteristics according to their reciprocal characteristics between lowering the ionization threshold and increasing the electro-negativity. As electric field increases, electrons with higher energies in the electron energy distribution also increase. The mean and characteristic electron energies also linearly increase with electric field. The variation of flue gas temperature did rarely affect on the electron energy distribution function and electron transport characteristics, because the gas temperature is several hundreds or thousands times lower than the electron temperature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.519-524
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• 2003

In this paper we discuss the dynamic characteristics of the in-arm type hydropneumatic suspension unit(ISU). For this, two accurate models are introduced. The first one is the Benedict-Webb-Rubin equation which is adopted for the spring behavior of a real gas. This equation is applicable for the high pressure of the nitrogen gas which acts as a spring in ISU system. The second one describes the behavior of a damper, which is divided into four parts - jounce-loading, jounce-unloading, rebound-loading and rebound-unloading. This approach gives a good approximation of the real damper system. For the comparison purpose, the numerical results of the dynamic behavior of ISU system using a real gas and an ideal gas are given in the paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.393-396
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• 1988

In discharge excited excimer laser, it is hard to say that the analysis of laser operation was well explained until now. But this can be improved by analysis the nonlinear discharge characteristics in the cavity. The nonlinear characteristics can be analysed by solving the nonlinear resistance which depends on electron mobility and number density. We can calculate the electron mobility and number density each other using Boltzmann equation and Kinetics equation. So we calculated the nonlinear resistance and analysed nonlinear discharge characteristics.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권11호
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• pp.597-603
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• 1999

Due to its simple construction, operation steadiness and low cost, claw pole step motor is widely used for OA machine and automobile. This paper deals with analysis fo claw pole motor, especially eyeing to dynamic characteristics. To analyze dynamic characteristics of claw pole step motor, torque development in each angular step of rotor are surveyed and torque equation is drived using permeance method. To adopt the airgap MMF, the magnetic equivalent circuit of the motor is introduced. On the base of the magnetic equivalent circuit, the air gap flux equation is derived. To get a optimum design of the motor, the torque characteristic is studied in variation of coil data and remanence value of permanent magnetic material.

• 한국방재학회 논문집
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• 제8권3호
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• pp.137-147
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• 2008

본 연구는 운동량방정식을 이루는 각 항의 상대적 크기를 해석적 방법으로 비교분석하였다. 운동량방정식의 매개변수인 하상 경사와 조도계수를 유출영향인자로 하여 각항의 시간적 변화를 분석하였다. 국지가속도와 대류가속도항의 크기는 서로 상쇄되는 경향을 보이며, 중력항을 제외한 나머지항들의 첨두치 발생시각은 수문곡선 상승부의 변곡점 발생시각과 일치함을 알 수 있다. 각 항의 상대적 크기는 하도특성에 따라 변하며, 특히 완경사 하천과 조도계수가 큰 경우는 압력항을 무시할 수 없음을 알 수 있다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권8호
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• pp.425-433
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• 2002

This research investigates the electromechanical characteristics of a sing1e-phase squirrel cage induction motor due to broken rotor bars and rotor eccentricity. Numerical analysis is performed by solving the nonlinear time-stepping finite element equation coupled with the magnetic field equation, circuit equation and mechanical equation of motion. It shows that the asymmetry of magnetic flux due to the broken rotor bars and rotor eccentricity introduce a change in the stator current, torque, speed, magnetic force and vibration of a rotor at the same time. However, even in the existence of rotor eccentricity, 3 broken rotor bar introduces a dominant change in the magnetic force and rotor displacement, i.e., beating phenomenon in time domain and sideband frequencies in frequency spectra, respectively.

• 한국분무공학회지
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• 제22권3호
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• pp.146-152
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• 2017

An experimental study was carried out to investigate the spray characteristics of non-circular effervescent twin-fluid nozzles. For this purpose, two types of non-circular nozzles (E1, E2) and circular nozzle (C) were used. Three types of aerorators with hole diameters of 1.2, 1.7 and 2.1 mm were used. Each aerorator has a total of 12 holes. It is defined by area ratio which is ratio of exit orifice area and aerator hole area. Experiments were carried out by controlling the amount of air flowing after fixing the flow rate of the liquid, and the nozzle internal pressure and SMD were measured, and the jet image was taken from the nozzles. The discharge coefficients of the three kinds of nozzles were compared with the used in plain orifice's equation and the Jedelsky's equation, and the Jedelsky's equation was found to be about 3 times larger. In addition, empirical formula based on ALR, which is the largest variable in Jedelsky's equation, was derived. The droplet sizes(SMD) were found to be smaller in the non-circular shape than in the circular shape, which is concluded to be caused by the difference of the discharge coefficients.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.448-448
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• 2000

This paper deals with dynamic behaviour analysis for pipeline inspection gauge (PIG) flow control in natural gas pipeline. The dynamic behaviour of the PIG is depending on the different Pressure between the rear and nose parts, which is generated by injected gas flow behind PIG's tail and expelled gas flow in front of its nose. To analyze the dynamic behaviour characteristics such as gas flow in pipeline, and the PIG's position and velocity, mathematical model is derived as two types of a nonlinear hyperbolic partial differential equation for unsteady flow analysis of the PIG driving and expelled gas, and nonhomogeneous differential equation for dynamic analysis of PIG. The nonlinear equation is solved by method of characteristics (MOC) with the regular rectangular grid under appropriate initial and boundary conditions. The Runge-Kuta method is used when we solve the steady flow equations to get initial flow values and the dynamic equation of PIG. The gas upstream and downstream of PIG are divided into a number of elements of equal length. The sampling time and distance are chosen under Courant-Friedrich-Lewy (CFL) restriction. The simulation is performed with a pipeline segment in the Korea Gas Corporation (KOGAS) low pressure system, Ueijungboo-Sangye line. The simulation results show us that the derived mathematical model and the proposed computational scheme are effective for estimating the position and velocity of PIG with different operational conditions of pipeline.

• 한국수자원학회논문집
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• 제43권3호
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• pp.265-273
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• 2010

본 연구에서는 기존의 수위만을 고려하여 작성된 수위-유량관계곡선식을 개선하기 위하여 경심, 하상경사, 수심 등 비교적 쉽게 취득할 수 있는 하천의 수리특성인자를 활용하여 유량을 산정할 수 있는 방법을 제안하였다. 알버타대학에서 제공된 보고서 내용 중 수리실험실 및 자연하천의 수리자료를 활용하여 평균유속 공식인 Manning식과 Chezy식으로부터 하천의 수리학적 특성이 반영된 조도계수 n값과 C값을 산정하고 이를 토대로 유량을 산정하였다. 제안된 유량산정 방법은 실측치에 근사하여 정확도가 개선됨을 확인하였으며 기존의 수위-유량관계곡선식에서 추정된 유량과 비교하고 그 적용성을 검토하였다.

• KIEAE Journal
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• 제9권1호
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• pp.107-113
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• 2009

The energy cost is resulted from the energy use. Its sources are divided into some types and depended on the building use or energy-use type. The energy cost should be affected by the amount of the energy use. The cost could be calculated to consider various factors such as the insulation, heating type, building shape and others. But it can not consider all of the affect factors to the energy cost and need to categorize the factors to the condition for estimating the cost. In this paper, it aimed at providing the estimation model in linear equation and multiple linear regression, utilizing the building exterior condition and management characteristics in apartment housing. Its survey are conducted in two parts of management characteristics and building exterior condition. The correlation analysis is conducted to get rid of the multicolinearity among the inputted factors. The number of linear equation model is 11 and includes the 1st, 2nd and 3rd equation function, power function and others. Among these, it suggested the 2nd and 3rd function and power function in terms of the statistics. In multiple linear regression model, the building volume and management area are inputted to the estimation.