• 한국자동차공학회논문집
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• 제10권5호
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• pp.1-8
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• 2002

For gasoline engines, a three-way catalytic converter that has the maximum efficiency at stoichiometric air/fuel ratio is used to clean up the exhaust gas. So a precise air/fuel ratio control is necessary to maximize the catalytic conversion efficiency, For a transient condition, a fred-forward air/fuel ratio control method that estimates the air mass inducted into a cylinder is being used. In this study, a fuel injection map that makes an accurate air/fuel ratio control possible was constructed for the very same transient condition. For the same condition above, intake air model and fuel model were refined so that fuel injection values based on air mass through a throttle valve and intake manifold pressure are equal to the map values.

• 한국자동차공학회논문집
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• 제21권1호
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• pp.78-85
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• 2013

This paper presents the sliding mode control methods for anti-lock brake system (ABS) with the friction force observer. Using a simplified quarter car model, the sliding mode controller for ABS is designed to track the desired wheel slip ratio. Here, new method to find the desired wheel slip ratio which produces the maximum friction force between road and tire is suggested. The desired wheel slip ratio is varying according road and tire conditions to produce maximum friction force. In order to find optimum desired wheel slip ratio, the sliding mode observer for friction force is used. The proposed sliding mode controller with observer is evaluated in simulation, and the control design is shown to have high performance on roads with constant and varying adhesion coefficients.

• 전력전자학회논문지
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• 제19권2호
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• pp.124-132
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• 2014

In this paper, we implement a non-time-varying transfer function of the duty ratio to improve the control characteristics in a control system that Input voltage and the output voltage is varied, DC / DC converters for bi-directional charging. When control is performed with using controller gain of conventional design, characteristics of the control is varied to fluctuations of the input voltage. The proposed method is the equivalently removing method for duty ratio in entire control block, by voltage controller gain is changed for inverse of the duty ratio. The proposed non-time-varying duty ratio transfer function is applied to DC / DC converter for bi-directional charging. In this paper, feasibility and superiority is verified through PSIM simulations and experiments.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.106-114
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• 2002

In this study, the air-fuel ratio(A/F) control characteristics of a liquid and a gaseous fueled engine are investigated. Engine models far both the liquid and the gaseous fueled engine are developed to compare the characteristics of fuel delivery into the cylinder, and the performances of the models are evaluated using the simulation and experiment. The simulation and experimental results show that the gaseous fueled engine has better control performance than that of the liquid fueled engine in terms of the air-fuel ratio control. This study could be used to develop air-fuel ratio control schemes for both the liquid and the gaseous fueled engine.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.129-138
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• 1999

In this paper, our main issue is that establishing the control procedure of continuous gas flow rate according to combustion fan RPM. For this, first, we decide the optimum operating condition of gas swirl burner through analysis of combustion characteristics - thermal efficiency, combustion efficiency and exhaust gases such as CO, $CO_{2}$, $O_{2}$, $NO_{x}$ and THC. Second, fuel gas flow rate of gas valve is decided with considering excess air ratio and combustion fan RPM is decided by the target of combustion air flow rate. Finally, experimental operating equation is acquired by regression for gas valve and combustion fan. This equation is the control equation of continuous gas flow rate and always gas flow rate is decided by combustion fan operating RPM.

• 한국물환경학회지
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• 제30권1호
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• pp.87-94
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• 2014

According to the technical guideline of water pollutant load management, the rainfall captured ratio which can be estimated by the empirical formula is an important element to estimate reduction loads of non-point pollutants water quality control basin. In this study, the rainfall captured ratio is altered to stormwater captured ratio considering its meaning in the technical guideline of water pollutant load management, and the new empircal formula of stormwater captured ratio is suggested. In order to do this, we calculate stormwater captured ratio by using the hourly rainfall data of seven urban weather stations (Busan, Daegu, Daejeon, Gangreung, Seoul, Gwangju, and Jeju) for 43 years. The regression coefficients of the existed empirical formula cannot reflect the catchment properties at all, because they are fixed values regardless of regions. However the empirical formula of stormwater captured ratio has flexible regression coefficients by runoff coefficient(C), so it is allowed to consider the characteristics of runoff in catchment. It is expected that reduction loads of storage based water quality control basin can be more reasonably estimated than before.

• 한국위성정보통신학회논문지
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• 제11권1호
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• pp.46-50
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• 2016

The adaptive power control of Code Division Multiple Access (CDMA) systems for communications between User Equipments (UEs) with a link-budget based Signal-to-Interference Ratio (SIR) estimate which has distance information is applied to three inner loop power control algorithms. The speed estimation performances of these algorithms with their consecutive Transmit-Power-Control (TPC) ratios are compared to each other, and it is concluded that the speed can be estimated using the TPC ratio information of Consecutive TPC Ratio Step-size Closed Loop Power Control (CS-CLPC) and Fixed Step-size Power Control (FSPC).

• Communications for Statistical Applications and Methods
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• 제16권4호
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• pp.713-722
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• 2009

The estimation of odds ratio and corresponding confidence intervals for case-control data have been done by traditional generalized linear models which assumed that the logarithm of odds ratio is linearly related to risk factors. We adapt a lower-dimensional approximation of Gu and Kim (2002) to provide a faster computation in nonparametric method for the estimation of odds ratio by allowing flexibility of the estimating function and its Bayesian confidence interval under the Bayes model for the lower-dimensional approximations. Simulation studies showed that taking larger samples with the lower-dimensional approximations help to improve the smoothing spline estimates of odds ratio in this settings. The proposed method can be used to analyze case-control data in medical studies.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.66-72
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• 1999

It is necessary to discuss lightening engine parts and reducing the friction of sliding parts to improve fuel consumption and combustion stability at idling condition. Lean best torque combustion which produce maximum power at a lean air-fuel ratio is effective for the reduction of exhaust gas emission and the improvement of fuel consumption. Accordingly, this study deals with the expansion of lean combustible limitation, the combustion stability and the reduction of idle speed through the analysis of combustion characteristics on the base of the control technique of precise air-fuel ratio because it does not need to maximum power at idling condition. The idle speed is increased proportional to ISC(Idle Speed Control) duty ratio. On the other hand the idle speed decreased by lean air-fuel ratio. The COV in engine speed is stable within maximum two percent up to 17.6 mixture ratio by the control of ISC duty ratio.

• 한국통신학회논문지
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• 제28권10B호
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• pp.854-861
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• 2003

본 논문에서는 ATM 망에서의 접속된 트래픽에 대해 효율적인 버퍼제어를 위한 퍼지제어 알고리즘을 제안한다. 제안된 퍼지 제어 알고리즘은 동적 서비스율을 구하기 위해 트래픽의 도착율과 버퍼점유률 그리고 퍼지집합을 사용한다. 즉, 발생된 전체 트래픽의 도착율과 버퍼점유률에 따라 퍼지논리를 기반으로 하여 추론한다. 그 후, 추론 결과로 얻어진 비퍼지화값으로 접속된 트래픽에 대해 서버에서의 서비스율을 제어하도록 하였다. 성능분석 결과 기존의 부분버퍼공유기법과 비교하여 셀손실율을 줄임으로서 그 성능이 향상되었다.