• Communications of the Korean Mathematical Society
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• v.28 no.1
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• pp.155-162
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• 2013

Although the snowflake curve, the boundary of the Koch snowflake, is one of the well-known fractals, there is no iterated function system (IFS) for it in the literature. In this study, we give an IFS for this familiar closed curve.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.90-93
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• 2003

The function, which represents the closed curve, is found from the sampling data by S-System in this study. Two methods are proposed. One is the extension of S-System. The data x and y are regarded as input data, and the data z=0 as output data. To avoid the trap into the invalid function, the judgment points (x$\_$j/, y/sug j/) are introduced. They are arranged in the inside and the outside of the closed curve. By introducing this concept, the functions representing closed curve are found by S-System. This method is simple because of a little extension of S-System. It is, however, difficult for the method to find the complex function like a hand-written curve. Then another method is also proposed. It uses the system incorporating the argument function. The closed curve can be expressed by the argument function. The relatively complex function, which represents the closed curve like a hand-written curve, is found by utilizing argument function.

• Journal of Magnetics
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• v.6 no.4
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• pp.142-144
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• 2001

A method to deduce the rotational magnetization curve from experimental magnetization of partially aligned uniaxial anisotropy system has been investigated. The curve obtained by this process has been evaluated quire close to the theoretical magnetization curve compared to that obtained by linear extrapolation from high field data. This new approach offers better accuracy for the determination of magnetic anisotropy by fitting a calculated magnetization curve to the obversed one.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.689-698
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• 2011

In South Korea, Total Maximum Daily Load (TMDL) has been enforced since 2004 to restore and manage water quality in the watersheds. However, the appraisal of TMDL in South Korea has lots of weaknesses to establish the plan for recovery of water quality because it just evaluates the target water quality during the particular flow duration interval. In the United States, Load Duration Curve (LDC) method bas been widely used in the TMDL to evaluate the water quality and pollutant loads considering variation of stream flow. In a recent study, web-based Load Duration Curve system was developed to create the LDC automatically and provide the convenience of use. In this study, web-based Load Duration Curve system was applied in the Gapyeongcheon watershed using the daily flow and 8-day interval water quality data, and Q-L Rating Curve was used to evaluate the water quality and pollutant load in the watershed, also. As a result of study, water quality and pollutant load in Gapyeongcheon watershed were met with water quality standard and allocated load in the all flow durations. Web-based Load Duration Curve system could be applied to the appraisal of South Korean TMDL because it can be used to judge the impaired flow duration and build up the plan of load reduction, and it could enhance the publicity. But, web-based Load Duration Curve system should be enhanced through addition of load assessment tools such as Q-L rating curve to evaluate water quality and pollutant load objectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1500-1506
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• 2008

In this paper, we proposed new reliability characteristic curve, which-can clearly show reliability property of transmission and substation system considering uncertainty such as frequency and duration of device fault. It express the relationship of duration of load curtailments, demand not supplied, and energy not served as “ y = $ax^{-1}$ " curve. and we proposed the method, which can objectively assess reliability of transmission and substation system using proposed characteristic curve as new reliability index. In this method, we used energy index of reliability(EIR) as a criterion of assessment. Finally, we performed a variety of case study for KEPCO system in order to verify usefulness of proposed method.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1424-1429
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• 2004

To seek the fan operating point on a cooling system with fans, it is very important to determine the system impedance and it has been usually examined with the fan tester(wind tunnel) based on ASHRAE standard and AMCA standard. This leads to a large investment in time and cost, because it could not be executed until the system is made actually. Therefore it is necessary to predict the system impedance curve through numerical analysis so that we could reduce the measurement effort. This paper presents how the system impedance curve (pressure drop curve) is computed by CFD in substitute for experiment. In reverse order to the experimental principle of the fan tester, pressure difference was adopted first as inlet and outlet boundary conditions of the system and then flow rate was calculated.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.1-11
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• 2012

This paper is the study on the development of a torque precision measuring system using the curve fitting algorithm. This system can be divided into the hardware part and the software part. The hardware part consists of the main base board, the DAQ(Data Aquisition) board and Calibration parts. The software part consists of the software filter module and the curve fitting algorithm module. We have tested the torque transducer including the strain gauge for 200 Nm range and have analyzed the data acquired with the curve fitting algorithm by using this system. The DAQ board converts the electric signal induced by the transducer to the digital value precisely by using the shunt calibration procedure. The main board including the curve fitting algorithm calculates the exact digital torque value by using the digital value from the DAQ board. In this study, we confirmed that the result of the appropriate high-order power-series polynomial function is more accurate than the result of the low-order power-series polynomial through the system.

• Korean Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.158-162
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• 1996

Algorithms to find the Bezier control points of the image of a Bezier domain curve on a Bezier surface are described. The diagonal image curve is analysed and the general linear case is transformed to the diagonal case. This proposed algorithm gives the closed form solution to find the control points of the image curve of a linear domain curve. If the domain curve is not linear, the image curve can be obtained by solving the system of linear equations.

• Korean Journal of Computational Design and Engineering
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• v.2 no.4
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• pp.253-266
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• 1997

Pencil-curve machining, which is a single-pass ball-end milling along a concave edge on adie surface, is widely employed in die-surface machining. The cutter-path used for pencil-curve machining, which is the trajectory of the “ball-center point” of a ball-endmill sliding along a concave-edge region on the die surface, is called pencil-curve. Presented in the paper is a pencil-curve tracing algorithm in which “concave-type” sharp edges are computed from a “virtually digitized” model of the tool-envelope surface. The resulting “initial” pencil-cures are then refuted by applying a series of fairing operations. illustrative examples and methods for enhancing accuracy are also presented. The proposed pencil-curve tracing algorithm has been successfully implemented in a commercial CAM system specialized in die-machining and in the CAD/CAM system CATIA.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.677-682
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• 2007

In the distribution system, Change of system happens frequently. However, most of the relays are operated manually by a person or not changed when system changed. So, when fault happened, a case that relaydoes not act rapidly happens. Also, in current power system, digital relays are used because of digitization of relay. Digital relay has very many advantages than existing analog relay. One of these advantages is that communication is available and easily can make characteristic curve. If specific values are sent to a relay by communication, A relay can make suitable characteristic curve according to the value. In this paper, by using voltages and currents measured by relay, state of CB(Circuit Breaker) and these relays, SCADA(Supervisory Control And Data Acquisition) system that control and correct characteristic curve of overcurrent relay at system change by using HMI(Human Machine Interface) is proposed.