• Korean Journal of Mathematics
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• 제9권2호
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• pp.115-121
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• 2001

In this paper, we establish the conditions that a mild C-existence family yields a solution to the abstract Cauchy problem. And we show the relation between mild C-existence family and C-regularized semigroup if the family of linear operators is exponentially bounded and C is a bounded injective linear operator.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.445-450
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• 2006

It is proposed that the electromechanical relation of the conductive materials with high electrical resistance may be used to estimate the current stress of prestressing tendons. To choose the best conductive material to this end, we studied the electromechanical relations of carbon fibers and metalic heat wires experimentally. It is found that the relation of carbon fibers can be modelled by a parabolic(or hyperbolic) function in the early stage of deformation. However because the relation is not consistent when it is unloaded and reload, carbon fibers are not suitable for this purpose. Metallic heat wires show a consistent linear relation during loading and unloading in the elastic deformation and are suitable for this purpose. To estimate the electromechanics relation of metallic wires, we developed a simple formula based on the rigid plasticity. We propose a new kind of prestressing tendons whose stress can be monitored.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.85-89
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• 2005

Lineament maps are the important tools that may reveal points of groundwater recharge, flow and development. In particular, groundwater flows and yields in mountainous area, composed of crystalline rocks with many fractures, are governed mainly by the lineaments corresponding to fractures, joints and faults. Lineaments may give important information on the best distribution of wells and their management. For two districts; Pohang and Cheonan, the relationship between lineament and groundwater factors was analyzed. To compare groundwater productivity, storativity, and transmissivity of a well site along the distance to lineament, the distances to lineament was regrouped into five groups with an equal range, 100m, for the Pohang district and they are also divided into five groups with an equal range, 150m, for the Cheonan district. From the results of the Spearman Rank Correlation Analysis and Kendall Analysis for each group, the means of SPC and T of wells which are located near lineaments generally have large values. The means of SPC and T show a reverse linear relationship with a lineament distance, but the means of S shows a disperse distribution and no distinct linear relation. Result of the linear regression model between SPC and lineament length density shows that it will be effective to use the lineament length density map when finding the optimal well site on a regional scale.

• 한국미생물·생명공학회지
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• 제27권1호
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• pp.54-61
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• 1999

Measurement of inhibition of bioluminescence in Photobacterium phosphoreum has been porposed as a sensitive and rapid procedure to monitor toxic substances. However, at first, $EC_{50}$ which shows degree of toxicity to each toxic substances must be calculated. QSAR (Quantitative Structure Activity Relationship) model can be used to estimate $EC_{50}$ to save time and endeavor. Moderately high correlation coefficients ($r^2{\geq}$ 0.97) were calculated from the linear correlation between $EC_{50}$ and molecular connectivity indices of CAHs (chlorinated aliphatic hydrocarbons)such as $^0X$, $^0X^V$, $^1X$, $^2X$ and $^3X^v_c$ and quadratic correlation between $EC_{50}$ and $^0X$, $^0X^V$, $^2X^V$, $^3X_c$, $^3X^V_c$ and P. It shows that the molecular connection indices in carbon structure is contributed to biological characters with linear relation and that in the other one with quadratic relation. The $EC_{50}$ of chlorophenol derivatives had quadratic relation with the value of octanol/water prtition coefficients ($r^2$=0.99) and linear and quadratic relation with the number of chlorine compound (($r^2{\geq}$0.94). This confirms the already known trend of increasing toxicity with increasing ability of a compound to diffuse through cell membrane and number of chlorine substitution.

• 대한수학회지
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• 제12권1호
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• pp.37-42
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• 1975

• 한국전산구조공학회논문집
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• 제13권3호
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• pp.361-371
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• 2000

RC 구조물은 서로 다른 재료적 특성을 지닌 콘크리트와 철근의 복합구조이고, 특히 콘크리트는 복잡한 소성거동을 나타내는 재료이다. 따라서 RC 구조물의 소성해석을 위해서는 콘크리트와 철근 각각의 재료특성과 소성거동을 묘사할 수 있는 세밀한 모델링 기법이 필요하지만, 이때 발생하는 모델링의 어려움, 모델링 규모, 계산용량 및 수렴성 등의 문제점으로 인하여 소성해석 수행에 많은 시간과 노력이 소요되거나 해석자체가 불가능하게 된다. 따라서 본 논문에서는 간편한 RC 구조물의 소성해석을 위해 RC 부재와 동일한 소성거동을 나타내는 균질·등방 재료로의 물성치환 방법을 제시하였다. 물성치환 원리는 RC 부재의 소성거동 특성, 즉 항복모멘트, 항복곡률 및 극한모멘트, 극한곡률로 표현되는 bi-linear 형태의 모멘트-곡률 관계를 이용하여, 이와 동일한 모멘트-곡률 관계(bi-linear 형태의 응력 변형률 관계)를 갖는 균질·등방 재료를 생성하였다. 또한 실제 RC 부재 해석모델과 치환된 균질·등방 재료를 이용한 해석모델에 대한 소성해석 결과를 비교·분석하여 본 연구의 타당성을 검증하였다.

• Journal of applied mathematics & informatics
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• 제26권5_6호
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• pp.1263-1272
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• 2008

Let T and S be bounded linear operators on Banach spaces X and y, respectively. A linear map A : X ${\rightarrow}$ y is said to be an intertwiner if AT - SA = 0. In this paper we study the relation between local spectral properties of T and S on the assumption of AT - SA = 0. We give some example of intertwiner with T and S.

• Water Engineering Research
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• 제1권4호
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• pp.293-298
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• 2000

Optimal values of $\alpha$ characterizing the linear dispersion property in the modified Boussinesq equations are determined by minimizing the combined relative errors of the phase and group velocities. The value of $\alpha$ is fixed in previous studies, whereas it is varying in the present study. The phase and group velocities are calculated by using variable $\alpha$ and compared to those of the linear Stokes wave theory and previous studies. It is found that the present study produces the best match to the linear Stokes theory.

• 대한수학교육학회지:학교수학
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• 제14권3호
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• pp.275-296
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• 2012

본 연구는 우리나라 초등학생들의 함수적 사고 능력의 실태를 알아보고자, 다섯 가지 유형의 함수적 관계로 구성된 검사지를 이용하여 2, 4, 6학년 학생 총 2087명의 반응을 분석하였다. 분석 결과, 함수적 관계에 대한 학생들의 이해는 지역규모나 성별에 따라 큰 차이가 나타나지 않았으며, 통계적으로도 유의미한 차이를 보이지는 않는 것으로 드러났다. 반면, 과제 유형이나 문제 상황별로는 학생들의 이해 정도에 다소 큰 차이가 나타났으며, 이러한 차이에 주의를 기울일 필요가 있음이 드러났다. 특히, x의 값이 임의의 수(${\Box}$)로 주어졌을 때 y값을 구하는 문항에서의 정답률은, x의 값이 큰수로 주어졌을때 y값을 구하는 문항에서의 정답률에 비하여 다소 높게 나타나는 경향이 발견되었다. 본 논문은 이러한 결과들을 토대로 초등학교에서의 함수적 사고 지도 방안에 대한 시사점을 제공하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1788-1789
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• 2011

In order to develop a one-axis gimbaled acoustic source tracker for mobile robots, a pseudo-linear direction of arrival(DOA) estimator is proposed using a linear ultrasonic sensor array. Under the assumption that the sensor measurement errors are negligible, a linear measurement model is derived using the linear prediction relation of the received sinusoidal acoustic signals. Applying the Kalman filtering technique for this model, the linear recursive DOA estimator is designed. For its linear recursive filter structure, it is preferable for real-time implementation on a commercial DSP. Through the experiments, the effectiveness of the suggested method is demonstrated.