• 한국기계가공학회지
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• 제16권3호
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• pp.1-8
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• 2017

Tool path generation is a part of process planning in 3D printing. This is done before actual printing by a computer rather than an AM machine. The mesh geometry of the 3D model is sliced layer-by-layer along the Z-axis and tool paths are generated from the sliced layers. Each 2-dimensional layer can have two types of printing paths: (i) shell and (ii) infill. Shell paths are made of offset loops. During shell generation, twists can be produced in offset loops which will cause twisted tool paths. As a twisted tool path cannot be printed, it is necessary to remove these twists during process planning. In this research, An algorithm is presented to remove twists from the offset loops. To do so the path segments are traversed to identify twisted points. Outer offset loops are represented in the counter-clockwise segment order and clockwise rotation for the inner offset loop to decide which twisted loop should be removed. After testing practical 3D models, the proposed algorithm is verified to use in tool path generation for 3D printing.

• 대한교통학회:학술대회논문집
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• 대한교통학회 2000년도 제37회 학술발표회논문집
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• pp.25-47
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• 2000

In route guidance systems fastest-path routing has typically been adopted because of its simplicity. However, empirical studies on route choice behavior have shown that drivers use numerous criteria in choosing a route. The objective of this study is to develop computationally efficient algorithms for identifying a manageable subset of the nondominated (i.e. Pareto optimal) paths for real-time vehicle routing which reflect the drivers' preferences and route choice behaviors. We propose two pruning algorithms that reduce the search area based on a context-dependent linear utility function and thus reduce the computation time. The basic notion of the proposed approach is that ⅰ) enumerating all nondominated paths is computationally too expensive, ⅱ) obtaining a stable mathematical representation of the drivers' utility function is theoretically difficult and impractical, and ⅲ) obtaining optimal path given a nonlinear utility function is a NP-hard problem. Consequently, a heuristic two-stage strategy which identifies multiple routes and then select the near-optimal path may be effective and practical. As the first stage, we utilize the relaxation based pruning technique based on an entropy model to recognize and discard most of the nondominated paths that do not reflect the drivers' preference and/or the context-dependency of the preference. In addition, to make sure that paths identified are dissimilar in terms of links used, the number of shared links between routes is limited. We test the proposed algorithms in a large real-life traffic network and show that the algorithms reduce CPU time significantly compared with conventional multi-criteria shortest path algorithms while the attributes of the routes identified reflect drivers' preferences and generic route choice behaviors well.

• Geomechanics and Engineering
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• 제9권5호
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• pp.669-685
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• 2015

A three-dimensional elastoplastic constitutive model, also known as a UH model (Yao et al. 2009), was developed to describe the stress-strain relationship for normally consolidated and over-consolidated soils. In this paper, an acoustic tensor and discriminator of bifurcation for the UH model are derived for the strain localization of saturated clays under undrained and fully and partially drained conditions. Analytical analysis is performed to illustrate the points of bifurcation for the UH model with different three-dimensional stress paths. Numerical analyses of cubic specimens for the bifurcation of saturated clays under undrained and fully and partially drained conditions are conducted using ABAQUS with the UH model. Analytical and numerical analyses show the similar bifurcation behaviour of overconsolidated clays in three-dimensional stress states and various drainage conditions. The results of analytical and numerical analyses show that (1) the occurrence of bifurcation is dependent on the stress path and drainage condition; and (2) bifurcation can appear in either a strain-hardening or strain-softening regime.

• 한국차세대컴퓨팅학회논문지
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• 제13권2호
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• pp.102-110
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• 2017

최근 자연어 처리 분야에서 단어의 모호성을 해소하기 위해서 다양한 기계 학습 방법이 적용되고 있다. 지도 학습에 사용되는 데이터는 정답을 부착하기 위해 많은 비용과 시간이 필요하므로 최근 연구들은 비지도 학습의 성능을 높이기 위한 노력을 지속적으로 시도하고 있다. 단어 모호성 해소(word sense disambiguation)를 위한 비지도 학습연구는 지식 기반(knowledge base)를 이용한 방법들이 주목받고 있다. 이 방법은 학습 데이터 없이 지식 기반의 정보을 이용하여 문장 내에서 모호성을 가지는 단어의 의미를 결정한다. 지식 기반을 이용한 방법에는 그래프 기반방식과 유사도 기반 방법이 대표적이다. 그래프 기반 방법은 모호성을 가지는 단어와 그 단어가 가지는 다양한 의미들의 집합 간의 모든 경로에 대한 의미 그래프를 구축한다는 장점이 있지만 불필요한 의미 경로가 추가되어 오류를 증가시킨다는 단점이 있다. 이러한 문제를 해결하기 위해 본 논문에서는 그래프 구축을 위해 불필요한 간선들을 배제하면서 반복적으로 그래프를 재구축하는 모델을 제안한다. 또한, 구축된 의미 그래프에서 더욱 정확한 의미를 예측하기 위해 하이브리드 유사도 예측 모델을 적용한다. 또한 제안된 모델은 다국어 어휘 의미망 사전인 BabelNet을 사용하기 때문에 특정 언어뿐만 아니라 다양한 언어에도 적용 가능하다.

• 전기학회논문지
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• 제60권12호
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• pp.2236-2245
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• 2011

This paper deals with the levitation force characteristics of electromagnet for MAGLEV vehicle application. The magnetic flux density distribution and levitation force characteristics of the electromagnet are investigated by means of equivalent magnetic circuit model. Firstly, we defined the aligned and unaligned electromagnet module for the full-electromagnet, and magnetic flux paths are represented for each model including leakage and fringing flux paths. Because of the analysis model contains both the permanent magnet and electromagnet coil, we calculated the airgap magnetic flux density and levitation forces using flux superposition in electromagnetic circuit. The results are validated extensively by comparison with finite element analysis. Moreover, the 1/4 scaled magnetic levitation and propulsion test vehicle has been manufactured and tested in order to verify these predictions. The experimental results confirms the validity of the analytical prediction with equivalent magnetic circuit model for the description of a electromagnet.

• 감성과학
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• 제17권2호
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• pp.13-24
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• 2014

Mobile phone makers compete for market shares through domination in media advertisements. These include domination of advertisements (Ads) in TV and the internet. However, the abundance and complexity of the competitions of Ads in TV does not guarantee advertising success which can influence consumers' emotion and the purchase intention towards the brand. This research analyses the case of a directional model on Attitude-towards-the-Ad model as a baseline into a new proposed correlation models (MacKenzie, Scott, &Lutz, 1989). The survey targets the involvements of Asian smartphone owners' attitude on advertisements, brands and purchase intentions. CFA (Confirmatory factor Analysis) was used in the research experiments, including hypothesis testing, the outcome of model fit which revealed significant levels and were successful. The study revealed that all three paths have consistently high coefficient paths (Attitude to Ads - Attitude to Brands - Purchase Intention), showing significant value of (${\beta}$=>.80), which supported each correlation factors. Therefore, this structural model, could set standards for creative managers and advertising teams to improve the brands visibility and build strong influences on attitudes in advertisements and improve purchase intentions.

• 대한간호학회지
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• 제34권1호
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• pp.172-181
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• 2004

Purpose: This study was designed to construct a structural model for explaining negative outcomes of anger in female adolescents. Methods: Data was collected by questionnaires from 199 female adolescents ina female high school in Seoul. Data analysis was done with SAS for descriptive statistics and a PC-LISREL Program for Covariance structural analysis. Results: The fit of the hypothetical model to the data was moderate, thus it was modified by excluding 7 paths and adding free parameters to it. The modified model withthe paths showed a good fit to the empirical data($x^2$ =5.62, p=.69, GFl=.99, AGFl=.97, NFI=.99, NNFI=l.01, RMSR=.02, RMSEA=.00). Trait anger, state anger, and psychosocial problems were found to have a significant direct effect on psychosomatic symptoms. State anger, psychosocial problems, and learning behaviorswere found to have direct effects on depression of female adolescents. Conclusion: The derived modelis considered appropriate for explaining and predicting negative outcomes of anger in female adolescents. Therefore, it can effectively be used as a reference model for further studies and is a suggested direction in nursing practice.

• 대한수학회논문집
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• 제12권3호
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• pp.789-796
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• 1997

We consider a Pfaffian and its combinatorial model. We give a bijection between Pfaffian and the generating function of weights of generalized Young tableaux by this combinatorial model, and we find an explicit formula for the Pfaffian by this bijection.

• 대한토목학회논문집
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• 제3권4호
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• pp.83-93
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• 1983

황해(黃海) 및 동지나해(東支那海)의 비선형조석(非線形潮汐)모델을 이용(利用)하여 대륙붕상(大陸棚上)의 평균(平均), 최대해저마찰응력(最大海底摩擦應力) 및 평균(平均), 최대토사이동(最大土砂移動)포텐셜을 구(求)하였다. 모델로부터 산정(算定)된 평균(平均), 최대해저마찰응력(最大海底摩擦應力)의 분포(分布)와 토사이동경로(土砂移動經路)와의 연관성(聯關性)에 대(對)한 초기추정(初期推定)이 이루어졌다.

• International Journal of Quality Innovation
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• 제1권1호
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• pp.64-74
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• 2000

This paper investigates the issue of performance testing on web browsing environments. Among the typical non-functional characteristics, index of link validity will be deeply explored. A framework to certify link correctness in web site is proposed. All possible navigation paths are first formulated to represent a usage model with the Markov chain property, which is then used to generate test script file statistically. With collecting any existing failure information followed by tracing these testing browsed paths, certification analysis may be performed by applying Markov chain theory. The certification result will yield some significant information such as: test coverage, reliability measure, confidence interval, etc. The proposed mechanism may provide not only completed but also systemic methodologies to find any linking errors and other web technologies errors. Besides, an actual practice of the proposed approach to a web-based system will be demonstrated quantitatively through a certification tool.