• 품질경영학회지
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• 제32권4호
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• pp.265-273
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• 2004

We got the growth distance curve by spline smoothing method with observed marketing data and the growth velocity curve by the derivation of the growth distance curve. Using this growth velocity curve, we defined the several characteristic points which describe the variation of marketing data. In this paper, to specify several patterns of marketing data, we suggested characteristic function by using these characteristic points. In addition, we applied characteristic function to the seventeen brands of electric home products data.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.362-369
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• 2005

Studying unsaturated soil mechanics, determination of soil water characteristic curve and permeability equation is an essential factor but it is not easy. In this research a new testing apparatus was developed to determine soil water characteristic curve and permeability equation. The testing to get saturated permeability coefficients and soil water characteristic curves for two soils was performed by using the developed testing apparatus. First, a saturated permeability testing was performed and then the testing to get soil water characteristic curve of a drying process was performed. Next, the testing to get soil water characteristic curve of a wetting process was performed. Testing results showed hysteresis phenomena between soil water characteristic curve of a drying process and soil water characteristic curve of a wetting process. The permeability equations were determined by a theoretical method where a saturated permeability coefficient and a soil water characteristic curve were used.

• 한국지반공학회논문집
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• 제21권5호
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• pp.59-64
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• 2005

불포화토를 연구하는데 있어 함수특성곡선과 투수계수방정식을 결정하는 것은 필수요소이나 이는 쉬운 일이 아니다. 본 연구에서는 함수특성곡선과 투수계수방정식을 얻기 위한 새로운 시험장치가 개발되었다. 개발된 시험장치를 사용하여 두 종류의 토사에 대해 포화투수계수시험과 함수특성곡선을 결정하기 위한 시험을 실시하였다. 시험진행순서는 먼저 포화투수계수시험을 실시한 후, 함수특성곡선의 건조과정에 대한 시험을 실시하고 다음으로 함수특성곡선의 습윤과정에 대한 시험순으로 진행하였다. 시험결과에 의하면 건조과정의 함수특성곡선과 습윤과정의 함수특성곡선 간에는 이력현상이 존재함을 알 수 있었다. 투수계수방정식의 결정은 시험으로부터 얻어진 포화투수계수와 함수특성곡선 이용하여 구하는 이론적인 방법을 사용하였다.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.5587-5594
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• 2012

불포화토 역학에 있어 흐름특성에 대한 규명은 지반공학적 문제들을 해결하는데 있어 매우 중요하다. 특히, 불포화토의 흐름특성을 모사하기 위한 첫 걸음이 되는 함수특성곡선의 측정을 위해서는 측정자의 오류를 최소화할 수 있는 신뢰성있고 편리한 기법이 필수적으로 요구되어진다. 플로우 펌프 시스템을 포함하여 현재까지 많은 연구자들은 함수특성곡선을 측정할 수 있는 다양한 기법들을 개발하였다. 본 연구에서는 기존에 제안되어진 플로우 펌프시스템을 활용한 흡입력 조절 기법을 이용하여 건조과정과 습윤과정에서 정확하게 실험 공시체의 함수특성곡선을 측정하였다. 플로우 펌프 시스템을 활용한 흡입력 조절 기법을 통하여 두 가지 시료의 함수특성곡선을 산정하였으며, 실험 결과를 바탕으로 흡입력 조절 기법은 현장 조건에 맞는 조건들을 실내에서 구현할 수 있으며 또한 건조과정과 습윤과정에서 발생하는 함수특성곡선의 이력현상을 규명하는데 적절한 장비인 것을 확인하였다. 특히, 플로우 펌프시스템을 활용한 흡입력 조절 기법은 자동화된 장비와 정밀도로 인하여 높은 정확도를 이끌어낼 수 있어 측정오차를 줄임과 동시에 측정시간을 절약하여 함수특성곡선을 측정할 수 있다.

• 한국정밀공학회지
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• 제21권12호
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• pp.37-43
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• 2004

The performance of magnetic abrasive finishing fur surface is evaluated by the characteristic curve. The characteristic curve is generated by experiment in surface finishing. For experiment, new magnetic inductor is designed and manufactured. 15 kinds of powders are provided to find the relationship between powder characteristic and finishing performance. As powder, Fe-TiC. Polymer-TiC and Fe-NbC are used with different size. The size of abrasives and location are also important factor for the performance. From characteristic curve, two index are obtained, which specify the initial finishing performance and endurance of finishing performance. It is proved that the performance index can be applied to select proper powder for efficient deburring. It is shown that the characteristic curve can be used as good tools for evaluating powder performance in surface finishing and deburring.

• 한국농공학회논문집
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• 제51권1호
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• pp.11-20
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• 2009

Flow pump technique was used in order to determine the soil-water characteristic curve of weathered granite soils in Pocheon area. This technique enables measurement to be more convenient and accurate as it is based on the CU condition of triaxial compression test. Besides, it is also able to measure dry and moisture curves continuously since the test is controled by means of a computer automatically. In this study, not only a hydraulic conductivity of weathered granite soils at fully saturated state in Pocheon area, but also a soil-water characteristic curve throughout unsaturate flow tests were determined. In addition, Brooks and Corey's model and Genuchten's model were used to simulate the soil-water characteristic curve. On the basis of the simulation an unsaturate hydraulic conductivity was predicted.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.146-153
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• 2004

The goals of this study are to investigate the feasibility of the reference state approach in determining the generalized soil-water characteristic curve that is essential for characterization of unsaturated soil behavior. The soil-water characteristic curves are obtained from a number of specimens of fine-grained residual soils compacted with different void ratios. Based on the experimental test results, the feasibility of using the liquid limit state as the reference state for predicting the soil-water characteristic curve are verified. Finally, through the regression analysis of experimental data using the equation of Fredlund and Xing (1994), a reliable method is proposed to predict the generalized soil-water characteristic curve of fine-grained residual soils using the liquid limit state as the reference.

• 전기학회논문지
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• 제57권9호
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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.

• 상하수도학회지
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• 제17권4호
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• pp.495-502
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• 2003

In order to modify incorrect flow data in the sewage system, the method using the stage-discharge relation and hydraulic characteristic curve of sewer pipe are applied. The modified data were verified with field measured data and the infiltration analysis using the modified data was carried out. When flowrate were measured using the flow-meter in fair weather, the stage data were comparatively consistent but velocity data were very poor for the most part. Therefore, it was recommended that sewage flowrate variation characteristic curve and infiltration were computed using the modified data on the basis of stage data. Especially, in the case of using the hydraulic characteristic curve, extrapolation results of the rainy season flowrate using regression curve on the basis of the data in fair weather were also reasonable.

• 한국지반공학회논문집
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• 제20권5호
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• pp.27-35
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• 2004

본 연구의 목적은 불포화토의 거동을 대변하는 흙-수분 특성곡선을 결정하는 데 있어서 액성한계상태를 이용한 비교상태접근법(reference state approach)의 적용 가능성을 확인하고 이를 바탕으로 하는 예측방법을 제안하는 데 있다. 세립잔적토를 사용하여 각기 다른 간극비로 다짐된 여러 개의 시료로부터 흙-수분 특성곡선을 구하였다. 실험결과를 바탕으로, 흙-수분 특성곡선을 예측하는 데 있어서 액성한계상태를 비교상태로 사용할 수 있음을 증명하였다. 마지막으로, Fredlund와 Xing(1994)이 제안한 흙-수분 특성곡선식을 사용하여 실험결과를 회귀분석 함으로서 액성한계를 비교상태로 하여 세립잔적토의 흙-수분 특성곡선을 예측할 수 있는 방법을 제안하였다.