• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.585-588
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• 2013

Electric motor with reduction gear systems are being adopted recently as main propulsion on the special-purposed ships. These specialized ships or offshore vessels require higher power rating generators for propulsion and accommodation power supply. This study investigated the cause of exciter components failure in the view of excessive vibration, force or abnormal ship motion in service. Countermeasures are proposed to address the exciter component failure. A 1.4 MW class dual-fuel engine generator using rigid foundation for a LNG carrier was used as research model.

• Journal of the Korean Society for Nondestructive Testing
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• v.10 no.1
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• pp.10-17
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• 1990

Recently, object recognition ultrasonic sensor is being used with automatization of industrial machine. Points which characterize the object can be deleted by measuring the propagation time of ultrasonic impulse and azimuth which gives its maximum amplitude, and from these points shape, position and orientation of the object are deduced. A new measuring method is adopted, where the distance to the object is calculated by sound reflection time which is measured from O-cross point of sound wave, and azimuth is measured by angle indicating maximum amplitude. The measuring accuracy of 1.0mm for distance and $0.5-2^{\circ}$ for azimuth have been accomplished. By rotational scanning of sensor the characteristic point of an object can be known and it gives the information of its shape, position and orientation. Experimental results showed that the object of some complicated shape can be recognized, which suggest its applicability to robot.

• Advances in materials Research
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• v.3 no.1
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• pp.237-257
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• 2014

In this paper, we adopted a two-dimensional analytical electro-elastic model to predict the stress distributions of the piezoelectric actuator in 3D case. The actuator was embedded in an elastic host structure under electrical loadings. The problem is reduced to the solution of singular integral equations of the first kind. The interfacial stresses and the axial normal stress in both plane stress state and plane strain state were obtained to study the actuation effects being transferred from the actuator to the host. The stress distributions of the PZT actuator in different length and different thickness were analyzed to guarantee the generality. The validity of the present model has been demonstrated by application of specific examples and comparisons with the corresponding results obtained from the Finite Element Method.

• Hwankyungkyoyuk
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• v.21 no.3
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• pp.41-47
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• 2008

This study aims to examine the reasons of changes in motivation of pre-service teachers who major in environmental education. Qualitative case study methods were adopted to collect and analyze data from six(6) pre-service teachers in environmental education department. Researchers conducted semi-structured interviews with them on the levels of motivation toward their studios. The study results are as follows. The levels of motivation toward their studies were shown differently by each of the pre-service teachers. Some of the pre-service teachers reported that their levels of motivation toward environmental education had changed since the college entrance. The reasons for the changes include 'suitability of environmental education to personal propensity,' 'college courses they took', and 'personal experiences.' Some of the pre-service teachers reported that the levels of motivation for their majors did not changed since he or she was pursuing other goals rather than being an environmental educator.

• Journal of Information Processing Systems
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• v.17 no.4
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• pp.675-689
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• 2021

Nowadays, cloud computing is being adopted for more organizations. However, since cloud computing has a virtualized, volatile, scalable and multi-tenancy distributed nature, it is challenging task to perform attack detection in the cloud following conventional processes. This work proposes a solution which aims to collect web server logs by using Flume and filter them through Spark Streaming in order to only consider suspicious data or data related to denial-of-service attacks and reduce the data that will be stored in Hadoop Distributed File System for posterior analysis with the frequent pattern (FP)-Growth algorithm. With the proposed system, we can address some of the difficulties in security for cloud environment, facilitating the data collection, reducing detection time and consequently enabling an almost real-time attack detection.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.3
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• pp.15-23
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• 2021

Personal Air Vehicle is expected to be a promising solution to relieve traffic congestion using urban airspace. The development of related technologies such as materials or batteries has been accelerated. In addition, commercial transportation services are being prepared. When fierce competition begins in the PAV market, even technologically superior products will disappear without choices by consumers. Therefore, demand factors should be reflected in PAV development to enhance competitiveness. In the paper, values were estimated for the major technological attributes of PAV. Stated preference data were collected through a survey, and the conjoint method and ordered probit model were adopted. Thereafter, it was confirmed that the value would be high in the order of dual mode, drone-type appearance, and noise reduction. Some R&D strategies were proposed based on this.

• Journal of KIBIM
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• v.11 no.1
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• pp.1-10
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• 2021

Blockchain is a secure technology that enables transactions between parties without risking data corruption. Besides cryptocurrencies, blockchain technology is being widely adopted in various forms by diverse industries. One promising application is construction contracts. Given that construction projects are executed under strict contractual requirements, blockchain technology-based contracts can ensure that contractual requirements are executed among parties to the contract. The objective of this study is to apply blockchain technology to smart construction contracts and determine their potential feasibility in construction management. In this study, a prototype smart construction contract is presented and its applicability is explored. We conclude that smart construction contracts can be effective as a contractual tool to enhance payment flows in the construction process.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.137-140
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• 2021

High dynamic range (HDR) technology has been drawing attention in the field of imaging and consumer entertainment. As tools for capturing and creating HDR contents, encoding, and transmission evolve to support HDR formats, various display capabilities are being developed and increased. Hence, there is need for remapping native HDR imagery for display on lower quality legacy standard dynamic range (SDR) displays. This operation is referred to as tone mapping. In this paper, we present a sectional tone mapping method by Lenzen, and expand upon a tone mapping approach to improve temporal stability while maintaining picture quality. Compared to the existing block-based sectional tone mapping, our method uses the edge awareness-based tone mapping. We estimate the performance of the objective metric on temporal flickering. The experimental result shows that the algorithm maintains a smoother relationship between the output luminance values, and this reveals success in reducing halos and improving temporal stability with adopted edge aware filtering.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.4
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• pp.1486-1501
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• 2021

The removal of accessories from the face is one of the essential pre-processing stages in the field of face recognition. However, despite its importance, a robust solution has not yet been provided. This paper proposes a network and dataset construction methodology to remove only the glasses from facial images effectively. To obtain an image with the glasses removed from an image with glasses by the supervised learning method, a network that converts them and a set of paired data for training is required. To this end, we created a large number of synthetic images of glasses being worn using facial attribute transformation networks. We adopted the conditional GAN (cGAN) frameworks for training. The trained network converts the in-the-wild face image with glasses into an image without glasses and operates stably even in situations wherein the faces are of diverse races and ages and having different styles of glasses.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.14-17
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• 2022

Due to the development of IT technology and the on-going Coronavirus disease, non-face-to-face services have been activated. To overcome the inconvenience of non-face-to-face service, service providers have adopted chatbots as a way to feel like a human being. As the increasing chatbot services, chatbot builders have emerged, which can help non-developers to build them. Although its popularity has increased, its performance evaluation has not been conducted on such chatbot builders. In this paper, we implement a prototype chatbot that classifies hospital departments in the medical field using Dialogflow and Rasa, which are popular chatbot builders. By measuring the accuracy of the chatbot's classification of medical subjects, we evaluated the level of accuracy that the most used chatbot builder can have when they are used to build a chatbot service. The simulation results showed that Dialogflow had 87%, 65%, and 60%, and Rasa did 64%, 70%, and 63% in surgery dermatology, and otolaryngology, respectively.