• Spatial Information Research
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• 제10권3호
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• pp.421-438
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• 2002

GIS을 활용하는 다양한 응용분야에서 공간데이터베이스의 상세한 정도(추상화 수준)는 그 목적에 따라 달라진다. 추상화 수준이 달라지면 공간자료의 기하학적인 단순화뿐 아니라, 객체(인스턴스), 공간 및 속성 자료, 위상관계, 의미관계 등이 변화되거나 유지되어야 한다. 이와 관련하여 본 연구에서는 원시 공간데이터베이스를 추상화하여 목표데이터베이스를 생성하는 방법을 제시하였다. 공간데이터베이스를 추상화하는 연산자를 재정의하고, 어떤 객체에 어떤 연산자들을 어떤 순서로 적용하여야 하는지에 대한 기준을 제시하고, 이 기준에 따라 워크플로우를 제시하였으며, 프로토타입시스템을 개발하여 타당성을 검토했다.

• 한국경영과학회지
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• 제23권2호
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• pp.131-156
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• 1998

Cooperative query answering is a research effort to develop a fault-tolerant and intelligent database system using the semantic knowledge base constructed from the underlying database. Such knowledge base has two aspects of usage. One is supporting the cooperative query answering Process for providing both an exact answer and neighborhood information relevant to a query. The other is supporting ongoing maintenance of the knowledge base for accommodating the changes in the knowledge content and database usage purpose. Existing studies have mostly focused on the cooperative query answering process but paid little attention on the dynamic knowledge base maintenance. This paper proposes a multi-level knowledge representation framework called Knowledge Abstraction Hierarchy (KAH) that can not only support cooperative query answering but also permit dynamic knowledge maintenance. The KAH consists of two types of knowledge abstraction hierarchies. The value abstraction hierarchy is constructed by abstract values that are hierarchically derived from specific data values in the underlying database on the basis of generalization and specialization relationships. The domain abstraction hierarchy is built on the various domains of the data values and incorporates the classification relationship between super-domains and sub-domains. On the basis of the KAH, a knowledge abstraction database is constructed on the relational data model and accommodates diverse knowledge maintenance needs and flexibly facilitates cooperative query answering. In terms of the knowledge maintenance, database operations are discussed for the cases where either the internal contents for a given KAH change or the structures of the KAH itself change. In terms of cooperative query answering, database operations are discussed for both the generalization and specialization Processes, and the conceptual query handling. A prototype system has been implemented at KAIST that demonstrates the usefulness of KAH in ordinary database application systems.

• 한국농공학회논문집
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• 제50권6호
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• pp.3-12
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• 2008

It is important to estimate accurate effective rainfall to analyse flood flow and long-term runoff for the rational planning, design, and management of water resource. The initial abstraction is also important to estimate effective rainfall. The Soil Conservation Service (SCS) has developed a procedure and it has been most commonly applied to estimate effective rainfall. But the SCS method still has weak points, because of unnatural assumptions such as antecedent moisture conditions and initial abstraction. The coefficient of initial abstraction(K) is depending on the soil moisture condition and antecedent rainfall. The maximum storage capacity of Umax which is calibrated by stream flow data in the proposed watershed was derived from the DAWAST(DAily WAtershed STreamflow) model. The values of K obtained from 69 storm events at the five watersheds are ranging from 0.133 to 0.365 and its mean value is 0.207. Effective rainfall could be estimated more reasonably by introducing new concept of initial abstraction. The equation of $K=0.076Sa^{0.255}$ was recommended instead of 0.2 and it could be applicable to the small-medium rural watersheds.

• 한국수학교육학회지시리즈A:수학교육
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• 제49권3호
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• pp.299-311
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• 2010

The purpose of this study was to examine the effects of abstraction offer of basic concept principle and feedback of self-efficacy attributional and mathematical study ability of math underachievers in high school based on the attribution theory and self-efficacy theory. The hypothesis were posed as below : Hypothesis 1: The experimental group that takes the abstraction offer of concept principle and attributional feedback training would be better at most self-efficacy than the control group that doesn't. Hypothesis 2: The experimental group that takes the abstraction offer of concept principle and attributional feedback training would have better math achievement than the control group that doesn't. They were divided into an experimental group and a control group, and the attribution disposition, self-efficacy and academic achievement of the children were measured by pretest and posttest. For data analysis, SPSS/PC+ program was employed and t-test was conducted. The main findings of this study were as below : First, the abstraction offer of concept principle and attributional feedback training was effective for enhancing the math self-efficacy in high school underachievers. Second, the abstraction offer of concept principle and attributional feedback training was effective for increasing the math achievement in high school underachievers.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2006년도 춘계학술대회
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• pp.354-360
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• 2006

The purpose of this paper is to propose a securely personalized context-aware cooperative query that supports a multi-level data abstraction hierarchy and conceptual distance metric among data values, while considering privacy concerns around user context awareness. The conceptual distance expresses a semantic similarity among data values with a quantitative measure, and thus the conceptual distance enables query results to be ranked. To show the feasibility of the methodology proposed in this paper we have implemented a prototype system in the area of site search in a large-scale shopping mall.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.67-74
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• 2008

The regional-scale transient groundwater-river interaction model is developed to gain a better understanding of the regional-scale relationships and interactions between groundwater and river system and quantify the residual river flow after groundwater abstraction from the aquifers with climate variability in the Waimea Plains, New Zealand. The effect of groundwater abstraction and climate variability on river flows is evaluated by calculating river flows at the downstream area for three different drought years (a 1 in 10 drought year, 1 in 20 drought year, and 1 in 24 drought year) and an average year with metered water abstraction data. The effect of future water demand (50 year projection) on river flows is also evaluated. A significant increase in the occurrence of zero flow, or very low flow of 100 L/sec at the downstream area is predicted due to large groundwater abstraction increase with climate variability. Modeling results shows the necessity of establishing dynamic cutback scenarios of water usage to users over the period of drought conditions considering different climate variability from current allocation limit to reduce the occurrence of low flow conditions at the downstream area.

• 한국컴퓨터정보학회논문지
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• 제9권3호
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• pp.1-6
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• 2004

객체 모델링 기법의 그래픽 표현을 이용하여 자료의 추상화, 캡슐화, 모듈화, 계층화 할 수 있는 새로운 그래픽 정보시스템 개발 기술이 절실히 필요하다. 그래픽 자료의 추상화 방법을 개선하기 위하여 복합객체 기술로 자료의 추상화와 계층화 개념을 기반으로 모델링하였으며, 메쉬, 레이어, 세그먼트, 인스턴스 등과 같은 여러 가지 도형요소의 클래스들을 지원하는 분류화와 다중상속 관계모델을 제안한다. 객체 모델링 기법과 스파이스 참조 모델을 이용하여 간단한 그래픽 정보시스템 개발사례를 통하여 소프트웨어 개발주기와 소프트웨어 유지보수 비용을 줄일 수 있는 요구사항을 지원하는 객체 표현 방법의 데이터 모델링 기법을 비교하고 평가한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.94-96
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• 2022

IoT 응용 개발에서 센서/구동기의 복잡성을 극복하기 위하여 Plug&Play 기법들이 다양한 방식으로 제안되었다. IEEE1451 표준은 센서/구동기를 TEDS 라는 자료구조로 추상화한다. 그 결과 센서/구동기를 호스트 장치에 연결할 때 센서/구동기의 특성이 불필요하다. ETRI에서 제안한 방식은 센서/구동기의 장치 드라이버가 호스트에 동적 적재 및 연결되는 형식이며 특별한 추상화 자료구조는 없다. 두 방식은 센서/구동기의 추상화 단위 면에서 양쪽 끝단에 위치한다. 우리는 이 사실을 기반으로 문제를 제시하는데 그 중간에 최적화된 어떤 방식이 존재할 수 있느냐는 것이다. 본 논문에서는 기존의 Plug&Play 기법들을 분석하고 추상화 단위를 정의하였다. 이 단위를 기반으로 기존 방식들을 비교, 분석하였다.

• 농촌계획
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• 제11권1호
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• pp.9-15
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• 2005

Preservation of geometrical context of terrains in a digitized format is useful in handling and making modification to the data. Digitization of three-dimensional terrain still proves a great challenge due to heavy load of context required to retain details of topological and geometrical information. Methods of simplification, restoration and multi-level terrain generation are often employed to transform the original data into a compressed digital format. However, reduction of the stored data size comes at an expense of loss of details in the original data set. This article reports on an alternative scheme for simplification and restoration of terrain data. The algorithm utilizes the fact that the terrain formation and patterns can be predicted and modeled through the fractal algorithm. This method was used to generate multi-level terrain model based on NGIS digital maps with preserving geometrical context of terrains.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1187-1194
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• 2011

The hydrogen abstraction reaction of $CF_3CH_2CHO$ + OH has been studied theoretically by dual-level direct dynamics method. Two stable conformers, trans- and cis-$CF_3CH_2CHO$, have been located, and there are four distinct OH hydrogen-abstraction channels from t-$CF_3CH_2CHO$ and two channels from c-$CF_3CH_2CHO$. The required potential energy surface information for the kinetic calculation was obtained at the MCG3-MPWB//M06-2X/aug-cc-pVDZ level. The rate constants, which were calculated using improved canonical transitionstate theory with small-curvature tunneling correction (ICVT/SCT) were fitted by a four-parameter Arrhenius equation. It is shown that the reaction proceeds predominantly via the H-abstraction from the -CHO group over the temperature range 200-2000 K. The calculated rate constants were in good agreement with the experimental data between 263 and 358 K.