• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.27-34
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• 2012

This paper proposes variable incremental conductance(IC) algorithm for maximum power point tracking(MPPT) control of photovoltaic. The conventional perturbation & observation(PO) and IC MPPT control algorithm generally uses fixed step size. A small step size reduces a tracking error in the steady state but slows a tracking speed in the transient state. Also, a large step size is fast a tracking speed but increases a tracking error. Therefore, this paper proposes variable IC MPPT algorithm that adjust automatically step size according to operating conditions. To improve a tracking speed and accuracy, when operating point is far from the maximum power point(MPP), the step size uses maximum value and when a operating point is near from the MPP, the step size uses variable step size that adjust according to slope of P-V curve. The validity of MPPT algorithm proposed in this paper prove through compare with conventional PO and IC MPPT algorithm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.11
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• pp.20-26
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• 2013

This paper proposes the maximum power point tracking(MPPT) control of photovoltaic system using fuzzy based variable step size perturbation & observation(FVSS-PO) method. Conventional PO and incremental conductance(IC)MPPT control algorithm generally uses fixed step size. A small fixed step size will cause the tracking speed to decrease and tracking accuracy of the MPP will decrease due to large fixed step size. Therefore, the fixed step size can't be satisfying both the tracking speed and the tracking accuracy. This paper proposes FVSS-PO MPPT algorithm that adjusts automatically step size of PO by fuzzy control according to operating conditions. The validity of MPPT algorithm proposed in this paper prove through compare with conventional PO MPPT algorithm.

• Korean Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.87-96
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• 1996

IGES is a file format which has gained widespread use but has certain limitations such as limited information coverage and ambiguous definitions. In order to overcome the limitations of existing neutral file formats, STEP has been developed as a more comprehensive mechanism for product data exchange by ISO. This paper describes a file translation system between IGES and STEP. In this system, three EXPRESS schemata are defined for IGES, STEP and the translation relationship between IGES and STEP. Object codes are generated from the schemata and linked with file access libraries to IGES and STEP files. The translation was verified by visualization and reverse translation. The system developed in this study can easily applied to translate other file formats because the file structure and translation relationship are defined in EXPRESS - a high level information modeling language.

• Computational Structural Engineering
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• v.8 no.4
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• pp.65-74
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• 1995

Direct method developed for the inelastic analysis of planar frames subjected to monotonic loads is extended to cyclic loads. Two frame elements for Direct Method(inelastic truss and inelastic beam) are developed. The accuracy and reliability of the preposed method is verified by comparing the analysis results of example with step-by-step analysis. Direct Method is superior to Step-by-step analysis in view of reliability of solution and analysis cost.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1712-1717
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• 1997

Stability and accuracy for the trapezoidal rule of the Newmark time integration method are analyzed when variable time step sizes are adopted. A new analytic approach to stability and accuracy analysis is also proposed for time integration methods with variable time step sizes. The trapezoidal rule with variable time step sizes has the "actual" unconditional stability which is the same as that of the method with constant time step sizes. However, the method with variable time step sizes is first-order accurate while the method with constant time step sizes is second-order accurate. accurate.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1239-1243
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• 2007

Autonomous Station Control System is automatic route control system of large-scale station. The system has flexibility of system step-by-step construction and expandability. A method of step-by-step construction for Autonomous Station Control System has system expansion and subsystem software expansion. The system has autonomous controllability and autonomous coordinability for system step by step construction. With property for a basis, each of subsystem communicates data field. Also, Each subsystem has its own management system, Autonomous Data Manager to manage itself and coordinate with the others. This paper make clear test method for Autonomous Station Control System expansion and software expansion. The first test method of system increasing construction is single station construction test. The second of method is connecting test the neighbor's Autonomous Station Control System. The third of method is connecting test the Autonomous Line Management System. Also, the test method of software expansion take the case of route control subsystem.

• Journal of the Korean Home Economics Association
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• v.44 no.1 s.215
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• pp.37-45
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• 2006

The study aimed to determine the effects of Early Childhood STEP on parenting stress and child's behavior. The study subjects were 29 Korean mothers and their child. The researcher translated the Parent's guide of the Early Childhood STEP into Korean, along with the video tapes for parents. The experimental group was educated with the Early Childhood STEP program (lecture, reading educational material, discussion, watching video). To determine the pre- and post-test differences of parenting stress and infant behavior, t-test was used. The results are presented below. First, Early Childhood STEP exhibited a decreasing effect on the parenting stress of mothers. Second, STEP exhibited a decreasing effect on the infant behavior, particularly the behaviors in the areas of incapability, revenge, and power reactions.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.190-200
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• 1996

Step-by-step time integration methods are widely used for solving structural dynamics problem. One difficult yet critical choice an analyst must make is to decide an appropriate time step size. The choice of time step size has a significant effect on solution accuracy and computational expense. The objective of this research is to derive error estimate for newly developed time integration method and develop automatic time step size control algorithm for structural dynamics. A formula for computing error tolerance is derived based on desired period resolution. An automatic time step size control strategy is proposed based on a normalized local error estimate for the generalized-α method. Numerical examples demonstrate the developed strategy satisfies general design criteria for time step size control algorithm for dynamic problem.

• Journal of the Korean institute of surface engineering
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• v.36 no.4
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• pp.339-346
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• 2003

Stainless steel wire has been used in industry, dental and medical parts. Especially, it has been used widely for the dental orthodontic materials. The orthodontic wire requires good mechanical properties, such as elastic strength, combined with a high resistance to corrosion. To increase elastic strength and good corrosion resistance, drawing methods(one-step and two-step drawing) have been used and the electrochemical characteristics of drawed wire have been researched using potentiodynamic method in 0.9％NaCl and field emission scanning electron microscope. The one-step drawed wire showed the formation of rough surface. The hardness and tensile strength of two-step drawed wire increased. For the case of two-step drawed wire, the corrosion resistance and pitting potential increased compared with one-step drawed wire due to the drawing induced small surface roughness, such as scratch. The passivation and active current density decreased as the reduction in area for drawing increased.

• Journal of the Semiconductor & Display Technology
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• v.9 no.3
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• pp.5-9
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• 2010

Recently, the important issues of solar cell are low cost and high efficiency. Making low cost and high efficiency solar cell, there are many effects to development of inexpensive wafer, simplify process and improve optical, electrical properties. In this the study, the 2 step texturing method using micro blaster was developed to decrease reflection of incident lights. Air bridge electrode structure is suggested to expand the effective surface area and decrease the series resistance of finger electrode. The effects of 1 step texturing and 2 step texturing by micro blaster are compared. Reflectance of 1 step and 2 step texturing are measured 28.7% and 25.5%, respectively. The reflectance of 2 step texturing sample is lower about 3.2% than 1 step textured sample.