• Communications for Statistical Applications and Methods
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• 제8권2호
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• pp.327-336
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• 2001

This work concerns estimating a regression function, which is not linear, using aggregate data. In much of the empirical research, data are aggregated for various reasons before statistical analysis. In a traditional parametric approach, a linear estimation of the non-linear function with aggregate data can result in unstable estimators of the parameters. More serious consequence is the bias in the estimation of the non-linear function. The approach we employ is the kernel regression smoothing. We describe the conditions when the aggregate data can be used to estimate the regression function efficiently. Numerical examples will illustrate our findings.

• Computers and Concrete
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• 제8권2호
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• pp.163-176
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• 2011

By virtue of chord-length density function from the field of statistical physics, this paper introduced a quantitative approach to estimate the distribution of cement paste thickness between aggregates in concrete. Dynamics mixing method based on molecular dynamics was employed to generate one model structure, then image analysis algorithm was used to obtain the distribution of thickness of cement paste in model structure for the purpose of verification. By comparison of probability density curves and cumulative probability curves of the cement paste thickness among neighboring aggregates, it is found that the theoretical results are consistent with the simulation. Furthermore, for the model mortar and concrete mixtures with practical volume fraction of Fuller-type aggregate, this analytical formula was employed to predict the influence of aggregate volume fraction and aggregate fineness. And evolution of its mean values were also investigated with the variation of volume fraction of aggregate as well as the fineness of aggregates in model mortars and concretes.

• 정보처리학회논문지D
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• 제9D권1호
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• pp.21-30
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• 2002

능동 데이터베이스 시스템은 특정한 상태를 탐지하는 능동규칙을 도입한다. 조건부 평가는 사건이 발생할 때마다 수행되기 때문에 조건부를 처리하는 방법에 따라 시스템의 성능에 중요한 영향을 미친다. 본 논문에서는 차이트리 구조, 분류트리, 그리고 집계함수 테이블을 생성하는 전처리 기능을 갖는 조건부 처리 시스템을 제안한다. 전처리는 능동규칙을 미리 파악할 수 있는 능동 데이터베이스의 특징 때문에 도입될 수 있다. 본 논문에서는 선택연산, 조인연산, 그리고 집계함수를 효율적으로 처리할 수 있는 차이트리를 제안하고 조건부의 처리 성능을 높인다. 그리고 조인연산을 효과적으로 처리하는 분류트리와 높은 처리비용을 요구하는 집계함수를 처리하는 집계함수 테이블을 제안한다. 본 논문의 조건부 처리 시스템은 전처리 기능에서 만들어진 조건부 처리 구조 때문에 조건 비교의 횟수를 감소시켜 능동규칙에서 조건부 처리의 성능 향상을 기대할 수 있다.

• 한국정보과학회논문지:데이타베이스
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• 제30권4호
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• pp.372-380
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• 2003

시간에 따라 변화하는 사건들을 저장하는 시간지원 데이타베이스에서 기존의 집계 처리 기법에 시간을 고려하여 처리하도록 확장해야 한다. 기존의 시간지원 집계 처리 기법들은 매번 질의의 대상이 되는 사건들이 다를 때마다 시간 구간을 반복해서 구하고 그 구간마다의 결과를 계산해야 한다는 문제점이 있다. 본 논문에서는 시간지원 데이타베이스에 저장된 사건의 시작 시간과 종료 시간만을 미리 읽어 들여서 구성한 시점 시퀀스를 이용하여 시간지원 집계를 처리하는 방법을 제안하였다. 또한 데이타베이스에서 저장된 사건의 삭제나 새로운 사건의 삽입에 따른 시점 시퀀스 갱신의 용이성에 대해서도 언급하였다. 시점 시퀀스는 시간 구간에 대한 정보를 미리 저장하고 있기 때문에, 질의의 대상이 되는 사건들이 다른 시간지원 집계 질의가 계속해서 들어올 때 기존의 방법에 비해 효율적으로 처리할 수 있다.

• 대한치과의사협회지
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• 제48권11호
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• pp.803-812
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• 2010

Regenerative endodontic procedure (REP) is a treatment option to replace damaged pulp tissue with the viable tissue which restores the normal function of the pulp-dentin complex. Possible reason for doing REP is not clearly known, however, clinicians perform REP in order to recover the histological structure as well as function of the traumatized and diseased tooth so that this tooth can restore its original root shape and thickness. This REP can be explained by the concept of revascularization or revitalization after induction of blood clot formation in the canal space. For this purpose, several treatment strategies have been suggested. In this regard, the rationale for the application of triantibiotics, calcium hydroxide or mineral trioxide aggregate is discussed in this paper. As a result, we will try to find the best method for REP by reviewing each available technique and their advantages and disadvantages.

• Management Science and Financial Engineering
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• 제2권1호
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• pp.73-101
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• 1996

We show assets can be classified into diversifiable risks and non-diversifiable risks based on aggregate endowment and spanning so that in equilibrium agents eliminate diversifiable risks which must have zero values. Consequently, the benchmark portfolio that represents a pricing operator should have only a non-diversifiable risk, aggregate endowment should earn a positive risk premium over a riskless asset, and, even in incomplete markets, there should be a pricing operator represented by a function of aggregate endowment if any asset mean-independent of aggregate endowment is diversifiable. These results apply to both the CAPM and a representative agent model.

• Korean Chemical Engineering Research
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• 제60권2호
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• pp.260-266
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• 2022

Average aggregate size in particulate suspensions is estimated with scaling theories based on fractal concept and elasticity of colloidal gel. The scaling theories are used to determine structure parameters of the aggregates, i.e., fractal dimension and power-law exponent for aggregate size reduction with shear stress using scaling behavior of elastic modulus and shear yield stress as a function of particle concentration. The structure parameters are utilized to predict aggregate size which varies with shear stress through rheological modeling. Experimentally rheological measurement is conducted for aqueous suspension of zinc oxide particles with average diameter of 110 nm. The predicted aggregate size is about 1135 nm at 1 s^-1 and 739 nm at 1000 s^-1 on the average over the particle concentrations. It has been found that the predicted aggregate size near 0.1 s^-1 agrees with that the measured one by a dynamic light scattering analyzer operated un-sheared.

• Journal of Computing Science and Engineering
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• 제1권2호
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• pp.211-232
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• 2007

In this paper we investigate some issues and solutions related to the design of a Data Warehouse (DW), storing several aggregate measures about trajectories of moving objects. First we discuss the loading phase of our DW which has to deal with overwhelming streams of trajectory observations, possibly produced at different rates, and arriving in an unpredictable and unbounded way. Then, we focus on the measure presence, the most complex measure stored in our DW. Such a measure returns the number of distinct trajectories that lie in a spatial region during a given temporal interval. We devise a novel way to compute an approximate, but very accurate, presence aggregate function, which algebraically combines a bounded amount of measures stored in the base cells of the data cube. We conducted many experiments to show the effectiveness of our method to compute such an aggregate function. In addition, the feasibility of our innovative trajectory DW was validated with an implementation based on Oracle. We investigated the most challenging issues in realizing our trajectory DW using standard DW technologies: namely, the preprocessing and loading phase, and the aggregation functions to support OLAP operations.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.111-114
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• 2006

Recently, it is increased on the concern for the reuse of waste concrete because of the shortage of natural aggregate and the increase of waste concrete. And recycled coarse aggregate is used variously, but the existing wet method producted recycled fine aggregate has problem like the high price facilities, the long time progress of the work and the poor of recycled fine aggregate. The aim of this study is to investigate outline and performance evaluation of the drying specific gravity separation method to product high duality recycled fine aggregate. Finally, this study is shown investigate process flowing of drying separation type with gravity manufacture, producte system and function of detail devices. The performance of the method of drying specific gravity separation is certificated as the qualities of recycled fine aggregate satisfied the KS

• 한국전산구조공학회논문집
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• 제25권3호
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• pp.227-235
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• 2012

대표적인 다상 재료인 콘크리트는 구성 성분의 공간적 분포에 의해 재료 특성이 큰 영향을 받는다. 특히 공극(void)은 콘크리트의 특성에 큰 영향을 주는 요인으로서, 콘크리트 내부에 분포하는 공극의 공간적 분포를 파악하는 것은 재료의 특성을 이해하는데 매우 중요하다. 본 연구에서는 콘크리트 내부에 존재하는 경량 골재의 공극 분포 분석을 위해서, CT(computed tomography)로부터 얻은 단면 이미지를 활용하여 생성된 3차원 경량 골재 이미지를 활용하여 공극 분포를 시각화(visualization)하였다. 방향에 따른 3차원 경량 골재 내부의 공극 분포 상태를 정성적으로 묘사하기 위해서 확률 분포 함수인 두점 상관함수(two-point correlation function)를 사용하여 공극의 공간적 분포 경향을 구(sphere)에 표현하였다. 또한 방향에 대한 골재의 강성도(stiffness)를 계산하여 각 방향에 따른 골재의 역학적 물성치 분포 변화를 확인하였다. 각 방향으로의 확률 분포 함수로 표현된 공극 분포와 강성도 분석함으로서 CT 이미지를 통한 공극 분포 특성 분석 및 경량 골재의 역학적 특성을 효과적으로 예측할 수 있음을 확인하였다.