• Journal of Photoscience
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• 제12권1호
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• pp.47-50
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• 2005

Mediumeffects have been explored on the competitive H-atom abstraction and SET-promoted, silyl-transfer reactions of excited states of silylalkyl-substituted phenyl ketones. The chemical selectivities of photochemical reactions of silylalkyl phenyl ketones appear to depend on medium polarity, medium silophilicity, added metal cation and alkyl length. Irradiations of silylalkylketones in aqueous solvent system and in presence of metal cation such as $Li^+$ and $Mg^{+2} $lead to formation of acetophenone predominantly by the sequential SET-silyl transfer route.

• 한국경영과학회지
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• 제32권1호
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• pp.125-136
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• 2007

The study on query relaxation which provides approximate answers has received attention. In recent years, some arguments have been made that semantic relationships are useful to present the relationships among data values and calculating the semantic distance between two data values can be used as a quantitative measure to express relative distance. The aim of this article is a hierarchical metricized knowledge abstraction (HiMKA) with an emphasis on combining data abstraction hierarchy and distance measure among data values. We propose the operations and the query relaxation algorithm appropriate to the HiMKA. With various experiments and comparison with other method, we show that the HiMKA is very useful for the quantified approximate query answering and our result is to offer a new methodological framework for query relaxation.

• 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.

• 한국학교수학회논문집
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• 제14권1호
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• pp.43-64
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• 2011

본 연구의 목적은 초등학교 6학년 아동을 대상으로 하여 수학적 모델링을 적용한 입체도형의 겉넓이 수업에서 학습이 이루어지는 동안 나타나는 학생들의 추상화 과정을 분석하고 학습에 대한 사전 사후의 겉넓이 이해 검사 결과를 비교함으로써 겉넓이에 대한 이해 정도를 알아보고자 함이다. 학생들의 추상화 과정을 분석한 결과 학생들은 주어진 수학적 모델링 과제를 해결하는 동안 수학적 원리를 포함한 모델을 개발하면서 모둠별로 각기 다른 수준의 추상화 과정을 나타냈으며, 겉넓이 이해 검사 결과 사후 검사에서 학생들의 겉넓이에 대한 이해가 향상되었다.

• 로봇학회논문지
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• 제2권3호
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• pp.262-269
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• 2007

Hierarchical Planning based on Abstraction of World Elements and Operators(HiPAWO) is proposed for mobile robots task planning, where abstraction of world elements is used for hierarchical planning and abstraction of operators is used for hierarchical decomposition of abstracted actions. Especially, a hierarchical domain theory based on JAH(Joint of Action Hierarchy)-graph is proposed to improve efficiency of planning, where a number of same actions are included in both adjacent hierarchical levels of domain theories to provide relationships between adjacent hierarchical levels. To show the validities of our proposed HiPAWO, experimental results are illustrated and will be compared with two other classical planning methods.

• 한국시뮬레이션학회논문지
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• 제9권4호
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• pp.41-50
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• 2000

We have many simulation constraints to meet as a modeled system becomes large and complex. Real-time simulations are the examples in that they are constrained by certain non-function constraints (e.g., timing constraints). In this paper, an enhanced hierarchical modeling methodology is proposed to efficiently deal with constraint-simulations. The proposed modeling method enhances hierarchical modeling methods to provide multi-resolution model. A simulation model is composed by determining the optimal level of abstraction that is guaranteed to meet the given simulation constraints. Four modeling activities are defined in the proposed method: 1) Perform the logical architectural design activity to produce a multi-resolution model, 2) Organize abstraction information of the multi-resolution model with AT (Abstraction Tree) structure, 3) Formulate the given constraints based on U (Integer Programming) approach and embrace the constraints to AT, and 4) Compose a model based on the determined level of abstraction with which the multi-resolution model can satisfy all given simulation constraints. By systematically handling simulation constraints while minimizing the modeler's interventions, we provide an efficient modeling environment for constraint-simulations.

• 한국컴퓨터정보학회논문지
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• 제21권12호
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• pp.227-234
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• 2016

In this paper, we propose a think-aloud program for acquiring abstraction concept. Think-aloud is a technique, which is good for teaching higher-order thinking skills to learner. We intend to propose a program for teaching abstraction concept to learners directly, as software education is being reinforced in the current education policy. For the study, we develop a program depending on ADDIE model. According to these steps, we analyzed related works such as computational thinking, think-aloud technique, and direct instructional model. After that, we split and structuralized the learning tasks for achieving a goal. And then, we constructed steps for the instruction and detailed contents of the program. We did a survey for verification to nine experts and we corrected the program according to it.

• 정보처리학회논문지D
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• 제17D권6호
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• pp.415-422
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• 2010

본 논문은 단위 컴포넌트가 제공하는 서비스를 중심으로 컴포넌트 행위모델을 합성하고 상위수준의 추상적 행위모델을 추출하는 서비스기반 합성과 검증기법을 제안한다. 이를 위하여, 상향식 행위양식 추상화의 기초가 되는 추상 컴포넌트를 정의하고, 포트기반 동기화 알고리즘과 서비스기반 투영을 통한 추상화기법을 제안하였다. 또한, 제안된 기법을 적용한 모델검증 프레임워크를 개발하고, 사례연구를 통하여 제안된 방식이 검증비용을 절감함을 입증하였다.

• ETRI Journal
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• 제46권3호
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• pp.501-512
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• 2024

With an explosive increase of data produced annually, researchers have been attempting to develop solutions for systems that can effectively handle large amounts of data. Single-operating-system (OS) non-uniform memory access (NUMA) abstraction technology is an important technology that ensures the compatibility of single-node programming interfaces across multiple nodes owing to its higher cost efficiency compared with scale-up systems. However, existing technologies have not been successful in optimizing user performance. In this paper, we introduce a single-OS NUMA abstraction technology that ensures full compatibility with the existing OS while improving the performance at both hypervisor and guest levels. Benchmark results show that the proposed technique can improve performance by up to 4.74× on average in terms of execution time compared with the existing state-of-the-art opensource technology.

• 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.