• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2277-2298
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• 2019

Adaptive learning in e-learning has garnered researchers' interest. In it, learning resources could be recommended automatically to achieve a personalized learning experience. There are various ways to realize it. One of the realistic ways is adaptive learning path recommendation, in which learning resources are provided according to learners' requirements. This paper summarizes existing works and proposes an innovative approach. Firstly, a learner-centred concept map is created using graph theory based on the features of the learners and concepts. Then, the approach generates a linear concept sequence from the concept map using the proposed traversal algorithm. Finally, Learning Objects (LOs), which are the smallest concrete units that make up a learning path, are organized based on the concept sequences. In order to realize this step, we model it as a multi-objective combinatorial optimization problem, and an improved immune algorithm (IIA) is proposed to solve it. In the experimental stage, a series of simulated experiments are conducted on nine datasets with different levels of complexity. The results show that the proposed algorithm increases the computational efficiency and effectiveness. Moreover, an empirical study is carried out to validate the proposed approach from a pedagogical view. Compared with a self-selection based approach and the other evolutionary algorithm based approaches, the proposed approach produces better outcomes in terms of learners' homework, final exam grades and satisfaction.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권11호
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• pp.681-688
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• 2015

k-Nearest Neighbor(k-NN)그래프는 모든 노드에 대한 k-NN 정보를 나타내는 데이터 구조로써, 협업 필터링, 유사도 탐색과 여러 정보검색 및 추천 시스템에서 k-NN그래프를 활용하고 있다. 이러한 장점에도 불구하고 brute-force방법의 k-NN그래프 생성 방법은 $O(n^2)$의 시간복잡도를 갖기 때문에 빅데이터 셋에 대해서는 처리가 곤란하다. 따라서, 고차원, 희소 데이터에 효율적인 Locality Sensitive Hashing 기법을 (key, value)기반의 분산환경인 MapReduce환경에서 사용하여 k-NN그래프를 생성하는 알고리즘이 연구되고 있다. Locality Sensitive Hashing 기법을 사용하여 사용자를 이웃후보 그룹으로 만들고 후보내의 쌍에 대해서만 brute-force하게 유사도를 계산하는 two-stage 방법을 MapReduce환경에서 사용하였다. 특히, 그래프 생성과정 중 유사도 계산하는 부분이 가장 많은 시간이 소요되므로 후보 그룹을 어떻게 만드는 것인지가 중요하다. 기존의 방법은 사이즈가 큰 후보그룹을 방지하는데 한계점이 있다. 본 논문에서는 효율적인 k-NN 그래프 생성을 위하여 사이즈가 큰 후보그룹을 재구성하는 알고리즘을 제시하였다. 실험을 통해 본 논문에서 제안한 알고리즘이 그래프의 정확성, Scan Rate측면에서 좋은 성능을 보임을 확인하였다.

• International Journal of Internet, Broadcasting and Communication
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• 제14권1호
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• pp.53-63
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• 2022

In the paper, we propose a TSCH-based scheduling scheme for IEEE 802.15.4e, which is able to perform the scheduling of its own network by avoiding collision from interference network cluster (INC). Firstly, we model a bipartite graph structure for presenting the slot-frame (channel-slot assignment) of TSCH. Then, based on the bipartite graph edge weight, we utilize the Hungarian assignment algorithm to implement a scheduling scheme. We have employed two features (maximization and minimization) of the Hungarian-based assignment algorithm, which can perform the assignment in terms of minimizing the throughput of INC and maximizing the throughput of own network. Further, in this work, we called the scheme "dual-stage Hungarian-based assignment algorithm". Furthermore, we also propose deep learning (DL) based deep neural network (DNN)scheme, where the data were generated by the dual-stage Hungarian-based assignment algorithm. The performance of the DNN scheme is evaluated by simulations. The simulation results prove that the proposed DNN scheme providessimilar performance to the dual-stage Hungarian-based assignment algorithm while providing a low execution time.

• 지능정보연구
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• 제11권1호
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• pp.153-167
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• 2005

본 논문에서는 이동 로봇이나 자율 캐릭터 에이전트로 미지의 환경을 탐사하는 문제를 다룬다 전통적으로 공간탐사 문제를 해결하기 위한 연구노력들은 주로 그래프기반의 공간 표현법들과 그래프 탐색법들에 초점을 맞추어 왔다. 최근 들어, 공간탐사를 위한 가장 효율적인 그래프 탐색법들 중 최대 $min(mn, d^2+m)$에지들만을 탐색하는 EXPLORE알고리즘이 발견되었다. 이때 d는 그래프의 부족도(deficiency)를 나타내고, m은 그래프 에지들의 수를, n은 그래프 노드들의 수를 나타낸다. 본 논문에서는 자율 에이전트에 의해 미지의 공간을 탐사하는 실시간 그래프 탐색 알고리즘 DFS-RTA*와 DFS-PHA*를 제안한다. 두 알고리즘들은 모두 EXPLORE 알고리즘과 같이 깊이-우선 탐색(DFS)을 기초로 하고 있으며, 직전 노드로의 빠른 후진을 위해 각각 실시간 최단 경로 탐색 방법인 RTA*와 PHA*를 적용하는 것이 특징이다. 본 논문에서는 대표적인 3차원 온라인 게임 환경인 Unreal Tournament게임과 지능형 캐릭터 에이전트인 KGBot를 이용한 실험을 통해 두 탐색 알고리즘의 완전성과 효율성을 분석해본다.

• 한국초등과학교육학회지:초등과학교육
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• 제31권3호
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• pp.321-333
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• 2012

The purpose of this study was to examine elementary school students' characteristics and difficulties in drawing and interpreting a line graph, and to present educational implications. Twenty five students(4th grader: 6, 5th grader: 9, and 6th grader: 10) at an elementary school participated in this study. We used a student's task which was about graphing on a given data table and interpreting his/her graph. The data table was on heating 200mL and 500mL of water and measuring their temperature at regular time intervals. We collected multiple source of data, and data analyzed based on the sub-variables of TOGS. The some results of this study are as follows: First, five children (20.0%), especially two of 10 sixth graders (20.0%), could not construct a line graph about a given data table. Second, twenty students (80.0%) had the ability on 'Scaling axes' and on 'Assigning variables to the axes', however, only a student understood why the time is on the longitudinal axis and the temperature is on the vertical axis. Third, in the case of 'Plotting points', twelve children (48.0%) could drew two graphs on a coordinate. Fourth, in the case of 'Selecting the corresponding value for Y (or X)', twenty student had little difficulty. on 'Describing the relationship between variables', seventeen students (68.0%) understood the relationship between time and temperature of water, and the relationship between temperature and amount of water. Finally, eleven students (44%) had the ability on 'Interrelating and extrapolation graphs.' Educational implications are also presented in this paper.

• Steel and Composite Structures
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• 제44권2호
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• pp.241-254
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• 2022

The cables in a cable-stayed bridge are critical load-carrying parts. The potential damage to cables should be identified early to prevent disasters. In this study, an efficient deep learning model is proposed for the damage identification of cables using both a multi-layer perceptron (MLP) and a graph neural network (GNN). Datasets are first generated using the practical advanced analysis program (PAAP), which is a robust program for modeling and analyzing bridge structures with low computational costs. The model based on the MLP and GNN can capture complex nonlinear correlations between the vibration characteristics in the input data and the cable system damage in the output data. Multiple hidden layers with an activation function are used in the MLP to expand the original input vector of the limited measurement data to obtain a complete output data vector that preserves sufficient information for constructing the graph in the GNN. Using the gated recurrent unit and set2set model, the GNN maps the formed graph feature to the output cable damage through several updating times and provides the damage results to both the classification and regression outputs. The model is fine-tuned with the original input data using Adam optimization for the final objective function. A case study of an actual cable-stayed bridge was considered to evaluate the model performance. The results demonstrate that the proposed model provides high accuracy (over 90%) in classification and satisfactory correlation coefficients (over 0.98) in regression and is a robust approach to obtain effective identification results with a limited quantity of input data.

• 인터넷정보학회논문지
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• 제25권1호
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• pp.69-78
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• 2024

최근 소비자들은 환경, 사회, 지배구조 관련 정보를 확인하고 더 나은 사회적 가치와 환경 친화적인 제품을 선택하려는 경향이 증가되고 있다. 본 논문에서는 GraphSAGE와 GAT를 결합한 모델인 MultiSAGE를 활용하여 최근 소비 트렌드인 가치소비에 맞추어 ESG 지표를 적용한 상품 추천 시스템을 제안하였다. 이를 위하여 한국 ESG 기준원에서 수집한 2022년 1,033개 기업의 ESG 등급 데이터와 실제 N기업의 쇼핑의 상품 데이터를 Heterogeneous Graph 형식의 데이터로 바꾸는 데이터 처리 과정과 MultiSAGE를 적용하여 머신 러닝에 적용하고, 특정 상품을 입력하면 그 상품의 친환경 대체재를 추천해주는 추천 시스템을 구현하였다. 구현결과, 소비자들은 기업의 ESG지표를 적용한 제품을 쉽게 비교하여 구매할 수 있고, 이를 통해 사회적 가치와 환경친화적인 제품을 추천하는 시스템에 활용될 것으로 기대한다.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 1999년도 추계학술대회-지능형 정보기술과 미래조직 Information Technology and Future Organization
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• pp.121-130
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• 1999

The objective of this paper is to apply Extended AND-OR Graph (EAOG)-related techniques to extract knowledge from a specific problem-domain and perform analysis in complicated decision making area. Expert systems use expertise about a specific domain as their primary source of solving problems belonging to that domain. However, such expertise is complicated as well as uncertain, because most knowledge is expressed in causal relationships between concepts or variables. Therefore, if expert systems can be used effectively to provide more intelligent support for decision making in complicated specific problems, it should be equipped with real-time inference mechanism. We develop two kinds of EAOG-driven inference mechanisms(1) EAOG-based forward chaining and (2) EAOG-based backward chaining. and The EAOG method processes the following three characteristics. 1. Real-time inference : The EAOG inference mechanism is suitable for the real-time inference because its computational mechanism is based on matrix computation. 2. Matrix operation : All the subjective knowledge is delineated in a matrix form, so that inference process can proceed based on the matrix operation which is computationally efficient. 3. Bi-directional inference : Traditional inference method of expert systems is based on either forward chaining or backward chaining which is mutually exclusive in terms of logical process and computational efficiency. However, the proposed EAOG inference mechanism is generically bi-directional without loss of both speed and efficiency.

• 한국정보시스템학회:학술대회논문집
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• 한국정보시스템학회 2003년도 춘계학술대회
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• pp.271-285
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• 2003

In the conduct of this study, a web-enabled healthcare system for the management of hypertension was implemented through a hyperlink-based inference approach. The hyperlink-based inference platform implemented using the hypertext capacity of HTML which ensured accessibility, multimedia facilities, fast response, stability, ease of use and upgrade, and platform independency of expert systems. Many HTML documents, which are hyperlinked to each other based on expert rules, were uploaded beforehand to perform the hyperlink-based inference. The HTML documents were uploaded and maintained automatically by our proprietary tool called the Web-Based inference System (WeBIS) that supports a graphical user interface (GUI) for the input and edit of decision graphs. Nevertheless, the editing task of the decision graph using the GUI tool is a time consuming and tedious chore when the knowledge engineer must perform it manually. Accordingly, this research implemented an automatic generator of the decision graph for the management of hypertension. As a result, this research suggests a methodology for the development of Web-enabled healthcare systems using the hyperlink-based inference approach and, as an example, implements a Web-enabled healthcare system for hypertension, a platform which peformed especially well in the areas of speed and stability.

• 정보관리학회지
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• 제31권1호
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• pp.231-250
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• 2014

정보통신기술의 발달로 학술 정보의 양이 기하급수적으로 증가하였고 방대한 양의 텍스트 데이터를 처리하기 위한 자동화된 텍스트 처리의 필요성이 대두되었다. 생의학 문헌에서 생물학적 의미와 치료 효과 등에 대한 정보를 발견해내는 바이오 텍스트 마이닝은 문헌 내의 각 개념들 간의 유의미한 연관성을 발견하여 의학 영역에서 상당한 시간과 비용을 줄여준다. 문헌 기반 발견 연구로 새로운 생의학적 가설들이 발견되었지만 기존의 연구들은 반자동화된 기법으로 전문가의 개입이 필수적이며 원인과 결과의 한가지의 관계만을 밝히는 제한점이 있다. 따라서 본 연구에서는 중간 개념인 B를 다수준으로 확장하여 다양한 관계성을 동시출현 개체와 동사 추출을 통해 확인한다. 그래프 기반의 경로 추론을 통해 각 노드 사이의 관계성을 체계적으로 분석하여 규명할 수 있었으며 새로운 방법론적 시도를 통해 기존에 밝혀지지 않았던 새로운 가설 제시의 가능성을 기대할 수 있다.