• FOCUS: LIFE SCIENCE
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• no.1
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• pp.9.1-9.5
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• 2024

Method development for complex low molecular mass (LMM) samples using reversed-phase (RP) separation conditions presents significant challenges due to the presence of many unknown analytes over wide concentration ranges. This guide aims to optimize method parameters-column length (L), temperature (T), flow rate (F), and final mobile phase conditions (Øfinal)-to maximize separation peak capacity. Validated by prior research, this protocol benefits laboratories dealing with metabolomics, natural products, and contaminant screening. This practical guide provides a structured approach to maximizing peak capacity for complex LMM separations. It complements computational optimization strategies and offers a step-by-step method development process. The Snyder-Dolan test is highlighted as essential for determining the need for gradient or isocratic elution and guiding column length decisions. The decision tree framework helps analysts prioritize variable optimization to develop effective separation methods for complex samples.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.3
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• pp.174-180
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• 2010

The inhomogeneous Helmholtz equation is introduced for variable water depth and potential function and separation of variables are introduced for the derivation. Only harmonic wave motions are considered. The governing equation composed of the potential function for irrotational flow is directly applied to the still water level, and the inhomogeneous Helmholtz equation for variable water depth is obtained. By introducing the wave amplitude and wave phase gradient the governing equation with complex potential function is transformed into two equations of real variables. The transformed equations are the first and second-order ordinary differential equations, respectively, and can be solved in a forward marching manner when proper boundary values are supplied, i.e. the wave amplitude, the wave amplitude gradient, and the wave phase gradient at a side boundary. Simple spatially-centered finite difference numerical schemes are adopted to solve the present set of equations. The equation set is applied to two test cases, Booij’ inclined plane slope profile, and Bragg’ wavy bed profile. The present equations set is satisfactorily verified against other theories including the full linear equation, Massel's modified mild-slope equation, and Berkhoff's mild-slope equation etc.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1990.10a
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• pp.47-52
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• 1990

This paper presents a cyclocoverter with a LC resonant circuit for a induction motor dr-ive. The cycloconverter can provide variab-le voltage and frequency three phase output while keeping the input displacement factor at 1.0. The input current wave forms are sinusoidal, and the wide output frequency ran-ge is appropriate for variable speed AC motor drives.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.182-185
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• 2003

Proposed Hybrid System is composed of phase leading capacitor banks, LC passive filters and active power filter. The passive power filter in parallel connection eliminate the 5th and 7th harmonics. The Variable capacitor banks correct the most of power factor, and the active power filter takes charge of remainder,

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.181-185
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• 2000

To get high efficiency in variable speed control of induction motor it is required that the vector control should be separated from flux components current and torque component current. In this paper the vector control is modeled by the estimation of the stator flex. Representing induction motor speed controller as a digital system with he use of he 32bit DSP improves the motor control performance The IGBT is used as the switching device and the validity of the proposed vector control is proved through voltage current wave and the characteristics of the velocity response as the drive circuit being simplified

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.981-984
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• 2004

This paper presents the design results and characteristic analysis of SRM. For vehicle power supply for adaptable design of the SRM, variable design parameters, such as stator and rotor laminations, winding details, pole numbers, and pole arcs, phases numbers are required. So, in this paper the SRM design results and the comparison of characteristics for vehicle power supply as phases changed are described.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.8
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• pp.539-546
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• 1987

In case of operating at Variable speed the induction motor by a frequency transformer, it will cause ripples in motor torque and considerably bad effects on the machines because the output side of the frequency transformer involves a great number of harmonics. This paper Presents the methods of decreasing torque ripples in induction motor and of improving current waveform, by means of forming the waveforms of output current into multi-step waveforms similiar to sinusoid, and also by means of eliminating the harmonic components maximally, in case of operating a 18-phase multi-inverter combining 3-step current source inverter.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1213-1218
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• 1993

Variable structure control is applied to the robust output tracking control problem of general nonlinear multi-input multi-output (MIMO) systems. Using the concept of relative degree and minimum phase, input/output(I/O) linearization is undertaken. For I/O the linearized system, a new sliding hyperplanes design method is proposed. In this procedure, we can construct very robust and efficient sliding mode controller for general nonlinear systems of relative degree higher than two. The control results are illustrated by adopting a numerical example.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.58-64
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• 1994

In this paper, a robust control scheme of a nonlinear system with norm bounded uncertainty is studied. The proposed algorithm is based on variable structure systems (VSS) theory. the sliding mode which is robust to plant uncertainty and disturbances is obtained by regulating a sliding surface equation. This VSS control law can improve the robustness of control systems by adjusting the minimum reaching velocity in a reaching phase. A numerical example is given to verify the effectiveness of the control law.

• 전기의세계
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• v.29 no.1
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• pp.58-64
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• 1980

In this paper, this objective is to obtain the mathematical model which describes the dynamic characteristics of variable reluctance(VR) step motor, the most important and most widely used motor in practice. In the development of the mathematical model for VR step motor, first the general nonlinear dynamic equations which describe the N-phase VR step motor are derived. These general equations are then applied to the multiple-step type of VR step motor in case, for simplicity, maynetic saturation and core lossess in the iron are neglected. These nonlinear dynamic equations are numerically analysed by the computer simulation, through which the performance characteristics of a step motor undertest are investigated under the various operating conditions.