• Journal of Korea Soil Environment Society
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• v.5 no.3
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• pp.65-75
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• 2001

This study purpose to elucidate the characteristics of water quality by elevation and groundwater samples has been studied with the samples from 150 selected groundwater represented the watershed of groundwater wells in Cheju Island. The evaluation of the characteristics of water quality utilized the physical and chemical property and the statistical analysis. According to the piper diagram, groundwater in the under 50 m region is shown N $a^{+}$＋ $K^{+}$-C $l^{[-10]}$ type, and that groundwater in the 50~100 m region is shown N $a^{+}$＋ $K^{+}$-HC $O_3$$^{[-10]}$ ＋C $O_3$$^{2-}$ type. and partly N $a^{+}$＋ $K^{+}$-C $l^{[-10]}$ type. In the above 100 m region belongs to N $a^{+}$＋ $K^{+}$-HC $O_3$$^{[-10]}$ ＋C $O_3$$^{2-}$ type. The result of factor analysis, commonly two factors as TDS(Total Dissolved Solid) and the contaminants extracted in the under 50m region and above 100 m region. Three factors were obtained from the result of the factor analysis in the 50~100 m region. Factor 1, consisting of TRS content. Factor 2, consisting of the contaminant and the dissolution of minerals. and Factor 3, consisting of HC $O_3$$^{[-10]}$ content. content.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1847-1852
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• 2003

Ultrasonic motors have many excellent performances. A variety of ultrasonic motors has been developed and used as an actuator in motion control systems. However, this motor has nonlinear characteristics. Therefore, it is difficult to achieve the precise position control system incorporating with the ultrasonic motor. This paper describes a position control scheme for traveling-wave type ultrasonic motor using a pseudo-derivative control with feedforward gains (PDFF) controller designed by the coefficient diagram method (CDM). The PDFF control system satisfies both the tracking and regulation performances, which are the most important for the precise position control system. The CDM is shown to be an efficient and simple method to design the parameters of PDFF controller. The effectiveness of the proposed control system is demonstrated by experiments.

• Journal of Educational Research in Mathematics
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• v.13 no.4
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• pp.495-506
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• 2003

In this study, 1 investigated some properties on the special hyper-dimensional figures made by the principle of the performance of equivalent forms representation. I supposed 2 definitions on the making n-dimensional figure : a cone type(hypercube) and a pillar type(simplex). We can explain that there exists only 6 4-dimensional regular polytopes as there exists only 5 regular polygons. And there are many hyper-dimensional figures, they all have sufficient condition to show the general Euler' Characteristics. And especially, we could certificate that the simplest cone type and pillar types are fitted to Pascal's Triangle and Hasse's Diagram, each other.

• Transactions of Materials Processing
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• v.17 no.7
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• pp.473-480
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• 2008

Sheet metal forming of Mg alloy is usually performed at elevated temperature because of the low formability at room temperature. Therefore, strain rates affected with the forming temperature and speed must be considered as important factor about formability. Effects of process parameters such as various temperatures and forming speeds were investigated in circular cup deep drawing. From the experimental results, it is known that LDR (Limit Drawing Ratio) increase as the strain rate increase. On the contrary, the FLD (Forming Limit Diagram) shows lower value as faster strain rate. Therefore, anisotropy values are investigated according to the temperature and strain rates at each forming temperature. R-values also represent higher value as faster strain rate. It is known that the formability can be different with the deformation mode on warm forming of AZ31 alloy sheet.

• Journal of KIISE:Software and Applications
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• v.26 no.1
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• pp.106-106
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• 1999

When we design real-time software target system is analyzed and then we structure sequential executive modules into concurrent tasks. As a result of the analysis, control flow and dataflow diagram based on the RTSA notation is produced. This diagram is structured into concurrenttasks under the condition that performance problem is not serious. The criteria structuring concurrenttasks are introduced as Concurrent Design Approach for Real-Time System(CODARTS) by Gomaa.But structuring concurrent tasks using the criteria of CODARTS is somewhat difficult because thecriteria are dependent on designer's experience. CODARTS is an wide-range and abstractmethodology. As a result, the design can be inconsistent and peoples can understand it differently Inthis paper, we restructure the CODARTS methodology, propose a revised CODARTS structure andrepresent the task structuring steps for this new framework to overcome the understanding andinconsistency problems. The revised CODARTS framework and task structuring steps can be used toautomate the design of real time concurrent software systems. Finally, we show an example of taskstructuring in revised CODARTS framework.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.139-142
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• 2002

제어 시스템에서 제어기를 설계하는 방법에는 기존 PID 설계 기법인 Ziegler-Nichols와 Jung, R. C. Dorf 방법들이 있다. 본 논문은 Shunji Manabe의 계수도법(CDM Coefficient Diagram Method)을 이용하여 Ball-Beam 시스템을 제어하기 위한 PID 제어기를 설계한다. PID 제어기의 각 파라메터인 P, I, D 계수는 시스템의 속도와 안정성에 기인하는 표준 안정도 지수$(\gamma)$와 등가시정수$(\tau)$ 로부터 얻 어진다. 등가시정수$(\tau)$와 안정도 지수$(\gamma)$는 제어기 파라메터의 대수적 형태와 절대적인 관계가 있다. 그러므로 설계된 제어기로부터 빠른 상승시간과 안정된 정상상태 응답을 얻을 수 있다. Ball-Beam 시스템에 CDM 제어기를 적용한 결과 시스템의 안정도, 정확성 그리고 강인성에 있어서 퍼지 제어기나 PID 제어기에 비해 뛰어난 응답 특성을 확인하였다

• The Journal of the Petrological Society of Korea
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• v.20 no.1
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• pp.23-37
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• 2011

The scaling properties on the length distribution of microcrack populations from Tertiary crystalline tuff are investigated. From the distribution charts showing length range with 15 directional angles and five groups(I~V), a systematic variation appears in the mean length with microcrack orientation. The distribution charts are distinguished by the bilaterally symmetrical pattern to nearly N-S direction. The whole domain of the length-cumulative frequency diagram for microcrack populations can be divided into three sections in terms of phases of the distribution of related curves. Especially, the linear middle section of each diagram of five groups represents a power-law distribution. The frequency ratio of linear middle sections of five groups ranges from 46.6% to 67.8%. Meanwhile, the slope of linear middle section of each group shows the order: group V($N60{\sim}90^{\circ}E$, -2.02) > group IV($N20{\sim}60^{\circ}E$, -1.55) > group I($N60{\sim}90^{\circ}W$, -1.48), group II($N10{\sim}60^{\circ}W$, -1.48) > group III($N10^{\circ}W{\sim}N20^{\circ}E$, -1.06). Five sub-populations(five groups) that closely follow the power-law length distribution show a wide range in exponents( -1.06 - -2.02). These differences in exponent among live groups emphasizes the importance of orientation effect. In addition, breaks in slope in the lower parts of the related curves represent the abrupt development of longer lengths, which is reflected in the decrease in the power-law exponent. Especially, such a distribution pattern can be seen from the diagram with $N10{\sim}20^{\circ}E,\;N10{\sim}20^{\circ}W$ and $N60{\sim}70^{\circ}W$ directional angles. These three directional angles correspond with main directions of faults developed around the study area. The distribution chart showing the individual characteristics of the length-cumulative frequency diagrams for 15 directional angles were made. By arraying above diagrams according to the categories of three groups(A, B and C), the differences in length-frequency distributions among these groups can be easily derived. The distribution chart illustrates the importance of analysing microcrack sets separately. From the related chart, the occurrence frequency of shorter microcracks shows the order: group A > group B > group C. These three types of distribution patterns could reveal important information on the processes occurred during microcrack growth.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.258-261
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• 2007

Failure phenomena in uni-axial tension test were experimentally and numerically investigated for AA6111-T4, AA5083-H18 and DP-Steel, which were friction-stir welded with the same and different thicknesses. Forming limit diagram(FLD) was measured using hemispherical dome stretching tests for base materials and also predicted by Hill's bifurcation and M-K theories for welded areas. Finite element simulations well predicted hardening behaviors, failure locations as well as failure patterns for the uni-axial tension tests especially utilizing very fine meshes and FLD along with stress softening.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.304-308
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• 2007

Failure phenomena in uni-axial tension test were experimentally and numerically investigated for AA6111-T4, AA5083-H18 and DP-Steel, which were friction-stir welded with the same and different thicknesses. Forming limit diagram(FLD) was measured using hemispherical dome stretching tests for base materials and also predicted by Hill's bifurcation and M-K theories for welded areas. Finite element simulations well predicted hardening behaviors, failure locations as well as failure patterns for the uni-axial tension tests especially utilizing very fine meshes and FLD along with stress softening.

• Journal of the Korean Society for Nondestructive Testing
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• v.4 no.1
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• pp.11-22
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• 1984

In the straight beam inspection of ultrasonic wave, the method for evaluating flaw size by AVG diagram is useful as a method for the quantitative evaluation of results of ultrasonic flaw detection. This study was carried out the measure the size of circular flat flaw with the inclination by straight beam inspection and could be decreased the error of application due to the inclination of flaw by AVG diagram in consideration of correction coefficient. From the result of the experiment, the error by means of the application of experimental values to AVG diagram was increased as the inclination angle grows. Also, it n s increased the error of application as the detecting frequency and diameter of flaw grows in the same inclination angle. In case of diameter of flaw 6mm, AVG diagram could be applied to the inclination angle $3^{\circ}$ for 5 MHz, $7^{\circ}$ for 2.25 MHz, $15^{\circ}C$ for 1 MHz in the range of 20% error and the theory was concided with the experiment to $5^{\circ}C$ for 5 MHz, $10^{\circ}C$ for 2.25 MHz, $15^{\circ}C$ for 1 MHz in the range of 10% error by correction eq. (45) due to the inclination angle. Therefore, it is considered that the results obtained from this study will be somewhat helpful informations for the size evaluation of circular flat flaw with the inclination.