• Korean Journal of Medicinal Crop Science
• /
• v.22 no.1
• /
• pp.17-22
• /
• 2014

Ginsenosides of roots in Panax ginseng were analyzed by metabolic-targeting HPLC using the partial least squares discriminant analysis (PLS-DA) and compared depending on sowing methods between direct seeding and transplanting method. Score plots derived from PLS-DA could identify the sowing method between the direct seeding and transplanting method in P. ginseng roots. The ginsenoside compounds were assigned as Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2, Rb3, and Rd. Contents of Re, Rf, Rg2, Rb1, Rc, Rb3, and Rd of main roots produced from the transplanting method were relatively higher than those of samples produced from direct seeding method. Also, contents of Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2, Rb3, and Rd of lateral roots from the transplanted samples were relatively higher than those of samples produced from direct seeding method. Therefore, HPLC with PLS-DA analysis can be a straightforward tool for identification of ginsenosides in main or lateral roots of P. ginseng obtained from two different seeding methods between direct and transplanting methods.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.7
• /
• pp.1061-1067
• /
• 2008

Direct Torque Control[DTC] and Vector Control are the two schemes developed for high performance induction motor drives. DTC based induction motors are being increasingly used in various industrial applications. DTC offers fast torque response and better speed control with lesser hardware and processing costs as compared to vector controlled drives. However, conventional DTC suffers from high torque ripple, current harmonics and low performance during torque transients. In this paper a new Direct Torque Control[DTC] method of induction motor is presented. In comparison with the conventional DTC method, the PWM technique is applied to proposed control method. In this method, decoupling mechanism is not required and the torque, the flux magnitude are under control using PI controllers and generating the voltage command for inverter control. Therefore torque and speed ripple could be reduced in comparison with the conventional switching table DTC.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.8
• /
• pp.1493-1502
• /
• 1992

The purpose of this study is to identify the effects of loading variables on fatigue crack opening behavior, using structural steel SS41. To use various stress ratios, three kinds of the methods varying stress ratio were used; .DELTA.P const., P$_{max}$ const., and P$_{min}$ const.. To measure the opening load, the direct measuring method which measures the distance between two micro indentations 20 .mu.m behind crack tip and the elastic compliance method were used. As the results of present study, the following conclusions are obtained. First, using the direct measuring method, it was possible to measure the COD at any location behind crack tip. Second, as measuring point becomes farther from crack tip, opening load becomes smaller. Third, the acceleration of da/dN near notch is due to crack opening behavior. Finally, opening ratio is a function of not only R, but .DELTA.K.K.K.

• Journal of Power Electronics
• /
• v.17 no.3
• /
• pp.674-685
• /
• 2017

The conventional model predictive direct torque control (MPDTC) method uses all of the voltage vectors available from a two level voltage source inverter for the prediction of the stator flux and stator current, which leads to a heavy computational burden. This paper proposes an improved model predictive direct torque control method. The stator flux predictive controller is obtained from an analysis of the relationship between the stator flux and the torque, which can be used to calculate the desired voltage vector based on the stator flux and torque reference. Then this method only needs to evaluate three voltage vectors in the sector of the desired voltage vector. As a result, the computational burden of the conventional MPDTC is effectively reduced. The time delay introduced by the computational time causes the stator current to oscillate around its reference. It also increases the current and torque ripples. To address this problem, a delay compensation method is adopted in this paper. Furthermore, the switching frequency of the inverter is significantly reduced by introducing the constraint of the power semiconductor switching number to the cost function of the MPDTC. Both simulation and experimental results are presented to verify the validity and feasibility of the proposed method.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.8 no.6
• /
• pp.602-614
• /
• 2016

It is necessary to develop an efficient optimization technique to perform optimum designs which have given design spaces, discrete design values and several design goals. As optimization techniques, direct search method and stochastic search method are widely used in designing of ship structures. The merit of the direct search method is to search the optimum points rapidly by considering the search direction, step size and convergence limit. And the merit of the stochastic search method is to obtain the global optimum points well by spreading points randomly entire the design spaces. In this paper, Pareto Strategy (PS) multi-objective function method is developed by considering the search direction based on Pareto optimal points, the step size, the convergence limit and the random number generation. The success points between just before and current Pareto optimal points are considered. PS method can also apply to the single objective function problems, and can consider the discrete design variables such as plate thickness, longitudinal space, web height and web space. The optimum design results are compared with existing Random Search (RS) multi-objective function method and Evolutionary Strategy (ES) multi-objective function method by performing the optimum designs of double bottom structure and double hull tanker which have discrete design values. Its superiority and effectiveness are shown by comparing the optimum results with those of RS method and ES method.

• The Research Journal of the Costume Culture
• /
• v.11 no.1
• /
• pp.11-19
• /
• 2003

This study suggests the new 2D anthropometric method using digital camera. It is used MK2001 program that can convert 2D measurements to 3D measurements. To improve that it is measured 100 college students with direct and indirect anthropometric method. The measurements were processed by the SPSS ver10 Statistical Package. The average, standard deviation, and t-test were calculated for each category. Most measurements by 2D measurements are higher than direct measurements but degree. The difference between direct and indirect measurements is less than 2cm. In the results of t-test, height measurements including other 16 measurements which is easy to measure have no meaningful difference within 1cm. The depth measurements are most high difference. The result of each measurement proves that MK2001 program (2D anthropometry method using digital camera) is available for measuring the human body.

• Journal of KSNVE
• /
• v.7 no.6
• /
• pp.975-984
• /
• 1997

A direct boundary element method (DBEM) is developed for thin bodies whose surfaces are rigid or compliant. The Helmholtz integral equation and its normal derivative integral equation are adoped simultaneously to calculate the pressure on both sides of the thin body, instead of the jump values across it, to account for the different surface conditions of each side. Unlike the usual assumption, the normal velocity is assumed to be discontinuous across the thin body. In this approach, only the neutral surface of the thin body has to be discretized. The method is validated by comparison with analytic and/or numerical results for acoustic scattering and radiation from several surface conditions of the thin body; the surfaces are rigid when stationary or vibrating, and part of the interior surface is lined with a sound-absoring material.

• Journal of Power Electronics
• /
• v.8 no.1
• /
• pp.74-80
• /
• 2008

This paper develops a direct torque control method (DTC) using a matrix converter fed induction motor. The advantages of matrix converters are combined with the advantages of the DTC technique; under the constraint of the unity input power factor, the required voltage vectors are generated to implement the conventional DTC method of induction motor. The proposed DTC algorithm is applied to induction motors and the experimental results are given in steady-state and transient conditions, while the discussion about the trend of the DTC method using the MC is also carried out. Furthermore, the entire system of the matrix converter configuration using 7.5kW IGBT module is explained in detail.

• Proceedings of the KIEE Conference
• /
• 2006.05a
• /
• pp.5-7
• /
• 2006

In this paper, developed a uninterruptible hotline tools and method for replacement of strain pole crossarm on overhead distribution line. For practical use of developed tools, following direct hot-line methods were proposed: 'Direct hot-lire method for replacement of pin pole crossarm', 'Direct hot-line method for alteration of crossarm' and 'Crossarm replacement method in uninterruptible cable displacement area'. These methods were proposed more simple and safe working on hotline job.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.10a
• /
• pp.387-394
• /
• 2004

In the structural analysis procedure using finite element technique, the performance of a linear equation solver is critical because the linear equation solving part spends most of the computing time for finite element analysis codes. However, most of researchers are still using inefficient profile-based direct solvers such as the band solver or the skyline solver. In this research, we introduce the multifrontal solution method as an efficient direct solution method for structural analysis, and show the efficiency and performance of the multifrontal solution method by comparing the performance of our own implementation of the multifrontal method with the band solver or the skyline solver. In addition, we also compare the performance of our solver with other implementations of the multifrontal method such as WSMP and MUMPS as well as commercial structural analysis packages such as ABAQUS and NASTRAN. Through the performance test results, the usefulness and efficiency of our domain-wise multifrontal solver for structural analysis is shown.