• 한국터널지하공간학회 논문집
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• 제16권6호
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• pp.533-542
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• 2014

본 연구에서는 Gehring, CSM, NTNU 모델을 이용한 디스크 커터 수명 예측 방법과 각 모델이 가지는 특징을 살펴보았다. 디스크 커터 수명에 크게 영향을 주는 요소인 관입깊이, 암석의 일축압축강도, 마모지수의 변화가 각각의 예측 모델들에 미치는 영향을 분석하였다. 디스크 커터 수명은 1회전당 관입깊이에 선형적으로 증가하였고, 일축압축강도의 증가에 따라 감소하는 경향을 보였다. 마모지수인 CAI 값이 증가함에 따라 Gehring과 CSM 모델에서의 디스크 커터 수명은 감소하였으나, CLI 값이 증가할수록 NTNU 모델의 디스크 커터 수명은 증가하는 경향을 보였다. 그리고 실제 현장 자료를 이용하여 디스크 커터 수명을 상호 비교하였다.

• International Journal of Precision Engineering and Manufacturing
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• 제9권2호
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• pp.69-74
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• 2008

Robotics and artificial intelligence are components of IT that involve networks, electrical and electronic engineering, and wireless communication. We consider an algorithm for efficient navigation by building a precise map in a multi-robot system under conditions of limited and unlimited communications. The basis of the navigation algorithm described in this paper is a wave algorithm, which is effective in obtaining an accurate map. Each robot in a multi-robot system has its own task such as building a map for its local position. By combining their data into a shared map, the robots can actively seek to verify their relative locations. Using shared maps, they coordinate their exploration strategies to maximize exploration efficiency. To prove the efficiency of the proposed technique, we compared the final results with the results in $Burgard^{8}$ and $Stachniss.^{9-10}$ All of the simulation comparisons, which are shown as graphs, were made in four different environments.

• 안보군사학연구
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• 통권2호
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• pp.237-260
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• 2004

As the research work about XML based on the development of Internet and according to the information exchange standard is being carried out, the need of discovering new methods to store XML documents and manage them efficiently according to the frequency of large-capacity XML documents increases. Consequently, as a kind of back-end database system, XML storage systems such as RDBMS, OODBMS and Native XML DBMS etc. are coming forth in order to save XML documents. It is an urgent task to make comparisons among usage expense, function comparison storage, inquiry, and manage dimension for each DBMS. This paper makes an analysis and comparison of DTD-independent XML document access methods in RDBMS, OODBMS and Native XML DBMS for XML storage and management. After analyzing the advantages and disadvantages of each access method and comparing the function of typical commerce DBMS such as Oracle 8i, eXcelon and Tamino for finding the possibility of military applications, an another appropriate method to save XML documents is proposed as to find an implementation approach to save structural XML documents.

• 동아시아경상학회지
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• 제3권3호
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• pp.14-26
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• 2015

A wind speed forecast is a crucial and sophisticated task in a wind farm for planning turbines and corresponds to an estimate of the expected production of one or more wind turbines in the near future. By production is often meant available power for wind farm considered (with units KW or MW depending on both the wind speed and direction. Such forecasts can also be expressed in terms of energy, by integrating power production over each time interval. In this study, we technically focused on mathematical modeling of wind speed and direction forecast based on locally data set gathered from Aghdasiyeh station in Tehran. The methodology is set on using most common techniques derived from literature review. Hence we applied the most sophisticated forecasting methods to embed seasonality, trend, and irregular pattern for wind speed as an angular variables. Through this research, we carried out the most common techniques such as the Box and Jenkins family, VARMA, the component method, the Weibull function and the Fourier series. Finally, the best fit for each forecasting method validated statistically based on white noise properties and the final comparisons using residual standard errors and mean absolute deviation from real data.

• 대한가정학회지
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• 제50권8호
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• pp.53-63
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• 2012

The purpose of this study is to examine the influence of the child-mother attachment and the child-father attachment (secure attachment, insecure avoidant and insecure disorganized attachment) on children's mutual friendships and mutual antipathy relations. The subjects consisted of 116 5-6 year old kindergarteners (64 boys & 52 girls) and they were asked to respond to the Attachment Story Completion Task by Bretherton & Cassidy (1990), based on the sociometric popularity postulated by Coie & Dodge (1988). Data were analyzed by the logistic regression analysis and the one-way ANOVA method and the Scheffe test in multiple comparisons analysis. The results concluded that 1)There were differences in terms of child-mother attachment and child-father attachment when it came to a child's mutual friendship. The secure child-mother and child-father attachment groups had more mutual friendships than the insecure attachment groups. 2)There were no differences in terms of child-mother attachment and child-father attachment when it came to child's mutual antipathy. 3) 78.0% of the mutual friendships were accurately classified as existence with respect to child-mother and child-father attachment.

• 산업경영시스템학회지
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• 제37권1호
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• pp.26-32
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• 2014

Mental fatigue is inevitable in the workplace. Since mental fatigue can lead to decreased efficiency and critical accidents, it is important to manage mental fatigue from the viewpoint of accident prevention. An experiment was performed to evaluate mental fatigue using the formant frequency analysis of human voices. The experimental task was to mentally add or subtract two one-digit numbers. After completing the tasks with four different levels of mental fatigue, subjects were asked to read Korean vowels and their voices were recorded. Five vowel sounds of "아", "어", "오", "우", and "이" from the voice recorded were then used to extract formant 1 frequency. Results of separate ANOVAs showed significant main effects of mental fatigue on formant 1 frequencies of all five vowels concerned. However, post-hoc comparisons revealed that formant 1 frequencies of "아" and "어" were most sensitive to mental fatigue level employed in this experiment. Formant 1 frequencies of "아" and "어" significantly decrease as the mental fatigue accumulates. The formant frequency extracted from human voice would be potentially applicable for detecting mental fatigue induced during industrial tasks.

• Journal of Power Electronics
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• 제8권2호
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• pp.181-191
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• 2008

The task performed by induction motors grows increasingly complex in modern industry and hence improvements are sought in the field of fault diagnosis. It is essential to diagnose faults at their very inception, as unscheduled machine down time can upset critical dead lines and cause heavy financial losses. Artificial intelligence (AI) techniques have proved their ability in detection of incipient faults in electrical machines. This paper presents an application of AI techniques for the detection of inter-turn insulation and bearing wear faults in single-phase induction motors. The single-phase induction motor is considered a proto type model to create inter-turn insulation and bearing wear faults. The experimental data for motor intake current, rotor speed, stator winding temperature, bearing temperature and noise of the motor under running condition was generated in the laboratory. The different types of fault detectors were developed based upon three different AI techniques. The input parameters for these detectors were varied from two to five sequentially. The comparisons were made and the best fault detector was determined.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.3942-3961
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• 2019

Recently, the models of deep super-resolution networks can successfully learn the non-linear mapping from the low-resolution inputs to high-resolution outputs. However, for large scaling factors, this approach has difficulties in learning the relation of low-resolution to high-resolution images, which lead to the poor restoration. In this paper, we propose Stage Generative Adversarial Networks (Stage-GAN) with semantic maps for image super-resolution (SR) in large scaling factors. We decompose the task of image super-resolution into a novel semantic map based reconstruction and refinement process. In the initial stage, the semantic maps based on the given low-resolution images can be generated by Stage-0 GAN. In the next stage, the generated semantic maps from Stage-0 and corresponding low-resolution images can be used to yield high-resolution images by Stage-1 GAN. In order to remove the reconstruction artifacts and blurs for high-resolution images, Stage-2 GAN based post-processing module is proposed in the last stage, which can reconstruct high-resolution images with photo-realistic details. Extensive experiments and comparisons with other SR methods demonstrate that our proposed method can restore photo-realistic images with visual improvements. For scale factor ${\times}8$, our method performs favorably against other methods in terms of gradients similarity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권10호
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• pp.3608-3626
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• 2021

The detection of bolts is an important task in high-speed train inspection systems, and it is frequently performed to ensure the safety of trains. The difficulty of the vision-based bolt inspection system lies in small sample defect detection, which makes the end-to-end network ineffective. In this paper, the problem is resolved in two stages, which includes the detection network and cascaded classification networks. For small bolt detection, all bolts including defective bolts and normal bolts are put together for conducting annotation training, a new loss function and a new boundingbox selection based on the smallest axis-aligned convex set are proposed. These allow YOLOv3 network to obtain the accurate position and bounding box of the various bolts. The average precision has been greatly improved on PASCAL VOC, MS COCO and actual data set. After that, the Siamese network is employed for estimating the status of the bolts. Using the convolutional Siamese network, we are able to get strong results on few-shot classification. Extensive experiments and comparisons on actual data set show that the system outperforms state-of-the-art algorithms in bolt inspection.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2359-2366
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• 2022

Selecting graphite grades with superior irradiation characteristics is important task for designers of graphite moderation reactors. To provide reference information and data for graphite selection, the effects of irradiation on three fine-grained, iso-molded nuclear grade graphites, ETU-10, IG-110, and NBG-25, were compared based on irradiation-induced changes in volume, thermal conductivity, dynamic Young's modulus, and coefficient of thermal expansion. Data employed in this study were obtained from reported irradiation test results in the high flux isotope reactor (HFIR)(ORNL) (ETU-10, IG-110) and high flux reactor (HFR)(NRL) (IG-110, NBG-25). Comparisons were made based on the irradiation dose and irradiation temperature. Overall, the three grades showed similar irradiation-induced property change behaviors, which followed the historic data. More or less grade-sensitive behaviors were observed for the changes in volume and thermal conductivity, and, in contrast, grade-insensitive behaviors were observed for dynamic Young's modulus and coefficient of thermal expansion changes. The ETU-10 of the smallest grain size appeared to show a relatively smaller VC to IG-110 and NBG-25. Drastic decrease in the difference in thermal conductivity was observed for ETU-10 and IG-110 after irradiation. The similar irradiation-induced properties changing behaviors observed in this study especially in the DYM and CTE may be attributed to the assumed similar microstructures that evolved from the similar size coke particles and the same forming method.