• Journal of Ocean Engineering and Technology
• /
• v.31 no.1
• /
• pp.60-68
• /
• 2017

In this study, we analyzed the real time video image obtained from the video monitoring system to grasp the shoreline, beach width, and area change of Haeundae beach. The video monitoring techniques enabled continuous monitoring for a long period at a much lower cost than general survey methods. It was possible to grasp quantitative beach variation characteristics of Haeundae beach through image acquisition, rectification, and image processing of video images. According to the monitoring results, the erosion rate of Haeundae beach in spring and summer was -19.8% in 2014 and -6.7% in 2015. The erosion rate in 2016 was -6.4%, which showed that the erosion rate in spring and summer continued to decrease. In particular, the influence of the erosion at the time of typhoon CHABA was revealed to be smaller than in the past. It can be concluded that these variations were due to beach width expansion by beach nourishment and the installation of submerged breakwaters.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.905-915
• /
• 2015

Two PWM techniques using space vector pulse-width modulation (SVPWM) are proposed for a two-phase permanent magnet synchronous motor (PMSM) driven by a two-phase eight-switch inverter. A two-phase motor with two symmetric stator windings is usually driven by a two-phase four-, six-, or eight-switch inverter. Compared with a four- and six-switch inverter, a two-phase eight-switch inverter can achieve larger power output. For two-phase motor drives, the SVPWM technique achieves more efficient DC bus voltage utilization and less harmonic distortion of the output voltage. For a two-phase PMSM fed by a two-phase eight-switch inverter under a normal SVPWM scheme, each of the eight PWM trigger signals for the inverter have to be changed twice in a cycle, causing a higher PWM frequency. Based on the normal SVPWM scheme, two effective SVPWM schemes are investigated in order to reduce the PWM frequency by rearranging four comparison values, while achieving the same function as the normal PWM scheme. A detailed explanation of the normal and two proposed SVPWM schemes is illustrated in the paper. The experimental results demonstrate that the proposed schemes achieve a better steady performance with lower switching losses compared with the normal scheme.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.5
• /
• pp.629-635
• /
• 2006

Manufacture of motor by laser has been studying realization that was demands on market for lightening and miniaturization. Moreover. early in the 1980s. manufacture of parts for automobiles by laser welding was already successfully introduced. The purpose of this study was to develop production technology of the high quality laminated stator core for motor by pulsed Nd:YAG laser heat source. In the event of adjusting defocus and voltage to control humping in laser welding of the laminated core. sound bead could be obtained. but deep penetration was not. Therefore. explosive evaporating plasma was controlled by adjustment of peak power on pulse width. Particularly, because explosive evaporating plasma induced high peak power, made molten metal in keyhole scatter. a suitable adjustment of peak power was required to obtain sound bead. As a results of experiment. sound bead and deep penetration could be obtained.

• Proceedings of the KIPE Conference
• /
• 2006.06a
• /
• pp.200-202
• /
• 2006

In this paper, a novel type of auxiliary active snubbing circuit assisted quasi-resonant soft-switching pulse width modulation inverter is proposed for consumer induction heating equipments. The operation principle of this high frequency inverter is described using switching modes and equivalent circuits. This newly developed series resonant high frequency inverter can regulate its high frequency output AC power under a principle of constant frequency active edge resonant soft-switching commutation by asymmetrical PWM control system. The high frequency power regulation and actual power conversion efficiency characteristics of consumer induction heating (IH) products using the proposed soft-switching pulse width modulation (PWM) series load resonant high frequency inverter evaluated. The practical effectiveness and operating performance of high frequency inverter are discussion on the basis of simulation and experimental results as compared with the conventional soft-switching high frequency inverter.

• Journal of Power Electronics
• /
• v.17 no.5
• /
• pp.1173-1185
• /
• 2017

In this paper, a new single phase multilevel inverter topology with a single DC source is presented. The proposed topology is developed based on the concepts of the L-Z source inverter and the switched capacitor multilevel inverter. The input voltage to the proposed inverter is boosted by two steps: the first step by an impedance network and the second step by switched capacitor units. Compared to other existing topologies, the presented topology can produce a higher boosted multilevel output voltage while using a smaller number of components. In addition, it provides more flexibility to control boosting factor, size, cost and complexity of the inverter. The proposed inverter possesses all the advantages of the L-Z source inverter and the switched capacitor multilevel inverter like controlling the start-up inrush current and capacitor voltage balancing using a simple switching strategy. The operating principle and general expression for the different parameters of the proposed topology are presented in detail. A phase disposition pulse width modulation strategy has been developed to switch the inverter. The effectiveness of the topology is verified by extensive simulation and experimental studies on a 7-level inverter structure.

• The Journal of the Korea Contents Association
• /
• v.10 no.4
• /
• pp.257-264
• /
• 2010

Though existent a transcranial magnetic stimulation makes various treatment and diagnostic sine waveform of fixed stimulation pulse, there is limitation. In this research, because strength, pulse width, pulse pattern required in treatment and diagnostic introduce other Cockroft-Walton circuit and half bridge inverter frequency and voltage variable become new device propose wish to. Have more advantages than existing device. First, do not have high voltage transformer. Second, switching loss can be less, and control output energy precisely. Three, stimulation strengths, pulse width, pulse pattern are various. As a result, sought special quality and an experiment that is improved applying inverter and cockroft - Walton circuit is half bridge inverter that do not use transformer.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.470-470
• /
• 2000

This paper describes a new method of identifcation of backlash nonlinear systems by use of M-sequence correlation method. In this method, we can obtain not only Volterra kernels of up to 3rd order of the nonlinear system, but also the width of the backlash element from observing the crosscorrelation between the input and the output. Here strictly speaking, a multi-valued nonlinear system such as backlash element can not be expressed by Volterra kernel representation mathematically. But in practice, we encounter many cases where it is difficult to treat them mathematically but they can be controlled from experience. So we here dare to suppose that backlash nonlinear system can be approximated by Volterra kernel representation. Simulations are carried out on a nonlinear system consisting of linear part plus backlash element. And Volterra kernels are measured. The output calculated from the observed Volterra kernels is in good agreement wi th the actual output. And we show that we can obtain the width of backlash element, which is one of the most important parameters, by observing the maximum value of crosscorrelation function between the input M-sequence and the output.

• Journal of Fashion Business
• /
• v.1 no.3
• /
• pp.95-102
• /
• 1997

This study is aimed for men's jacket draft not only to other style but also helping for men's jacket fits for trend by presenting the course to get a style we want by adding to the partial drafty changes in existing pattern of men's formal jacket selected two kinds of men's jacket style fit for 1997 S/S trend. In this 1997 S/S trend, the trend I of the characteristic formal jacket is a style slim expressed over the basic formal wear, and trend II of the characteristic casual jacket appears to women's wear that roundly expressed by collar line of V-zone returened back by the shoulder line of jacket made of a big diagonal wrinkled line of X-style in front centered around a button of center front line. In this study, it called that the existing traditional formal jacket of men is a A style of jacket and jacket style I, II is a jacket B, C style. Jacket A, B, C style, a distingtion in draft that added to make form an oblique wrinkled line of the X-shaped-making artificially to the front button line sharply distinguished by eyes will be come out by control of front neck width over the back neck width. According to this, we shall be found that place of front neck point is a cardinal point in draft that will be added any changes in a style of jacket.

• Laser Solutions
• /
• v.18 no.4
• /
• pp.1-5
• /
• 2015

For continuous laser micro patterning on three-dimensional free form surface, innovative laser system is developed. The two axis galvanometer is combined with the dynamic focusing unit to increase optical distance. Also, it is synchronized with the 3 axis mechanical system. To determine laser machining sequence, laser CAM system is developed. It can make possible of 3D surface micro patterning under $25{\mu}m$ pattern width. The uniformity of pattern width is about 2.8% and it is validated that focal plane is well conserved by the dynamic focusing unit. Velocity and positional information of 1 axis is stage is fed to the scanner control board by the encoder signal and it makes possible real time synchronization. With this system, possible patterning volume is enlarged from $40{\times}40mm^2$ to $40{\times}120{\times}30mm^3$.

• Agribusiness and Information Management
• /
• v.7 no.1
• /
• pp.1-9
• /
• 2015

The purpose of this study is to develop a growth prediction model that can predict growth and development information influencing the production of citrus fruits: the growth model algorithm that can predict floral leaf ratio, number of fruit sets, fruit width, and overweight depending on the main period of growth and development with consideration of the applied weather factors. Every year, large scale of manpower was mobilized to investigate the production of outdoor-grown citrus fruits, but it was limited to recycling the data without an observation supporting system to systemize the database. This study intends to create a systematical database based on the basic data obtained through the observation supporting system in application of an algorithm according to the accumulated long term data and prepare a base for its continuous improvement and development. The importance of the observed data is increasingly recognized every year, and the citrus fruit observation supporting system is important for utilizing an effective policy and decision making according to various applications and analysis results through an interconnection and an integration of the investigated statistical data. The citrus fruit is a representative crop having a great ripple effect in Jeju agriculture. An early prediction of the growth and development information influencing the production of citrus fruits may be helpful for decision making in supply and demand control of agricultural products.