• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.183-191
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• 2021

Non-intrusive load monitoring is a technology that can be used for predicting and classifying the type of appliances through real-time monitoring of user power consumption, and it has recently got interested as a means of energy-saving. In this paper, we propose a system for classifying appliances from user consumption data by combining GAF(Gramian angular field) technique that can be used for converting one-dimensional data to the two-dimensional matrix with convolutional neural networks. We use REDD(residential energy disaggregation dataset) that is the public appliances power data and confirm the classification accuracy of the GASF(Gramian angular summation field) and GADF(Gramian angular difference field). Simulation results show that both models showed 94% accuracy on appliances with binary-state(on/off) and that GASF showed 93.5% accuracy that is 3% higher than GADF on appliances with multi-state. In later studies, we plan to increase the dataset and optimize the model to improve accuracy and speed.

• Science of Emotion and Sensibility
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• v.24 no.4
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• pp.69-78
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• 2021

The development of smart healthcare wearables for health is accelerating. Among them, many wearable products using EMS electrical stimulation, which is one of the active research fields, have been released. However, the EMS wearable, which has been studied or released, is released in a comprehensive full-body suit that does not focus on muscle segmentation or a belt that covers the entire abdomen. Therefore, this study intends to use two breathing methods by applying an EMS pattern that subdivides specific muscles and attach a stretch sensor that can measure breathing to the abdominal pressure belt. The measurement method was conducted by inhaling and exhaling, and the subjects were 10 men in their 20s with healthy bodies. As a result of this study, the sensor's sensitivity was 5 and 3 mm, and the basic sensor in both thoracic and abdominal breathings and the EMS abdominal pressure belt showed improved respiration activation after applying electrical stimulation before and after application. It is concluded that, because of the two patterns produced based on the physical function, the difference in respiration activation effect and sensitivity between sensors could be confirmed with three sensors rather than not applying electrical stimulation suitable for the respiration method. Based on the results of this study, a follow-up study aims to develop breathing smart clothing that can be monitored in real time in clothing-type wearable products that incorporate EMS patterns and stretch sensors.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.367-372
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• 2022

With the recent advent of the New Normal era, realistic technologies and non-contact technologies are receiving social attention. However, the hair styling field focuses on the direction of the hair itself, individual movements, and modeling, focusing on hair simulation. In order to create an improved practice environment and demand of the times, this study proposed a non-contact hair styling VR system. In the theoretical review, we studied the existing cases of hair cut research. Existing haircut-related research tend to be mainly focused on force-based feedback. Research on the interactive haircut work in the virtual environment as addressed in this paper has not been done yet. VR controllers capable of finger tracking the movements necessary for beauty enable selection, cutting, and rotation of beauty tools, and built a non-contact collaboration environment. As a result, we conducted two experiments for interactive hair cutting in VR. First, it is a haircut operation for synchronization using finger tracking and holding hook animation. We made position correction for accurate motion. Second, it is a real-time interactive cutting operation in a multi-user virtual collaboration environment. This made it possible for instructors and learners to communicate with each other through VR HMD built-in microphones and Photon Voice in non-contact situations.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.14-14
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• 2023

산업발전에 따른 인구증가, 기후위기에 따른 가뭄 및 물 부족심화, 그리고 수질오염 등은 2015년 제79차 UN총회의 물 안보측면에서 국제사회의 물 분야 위기관리를 위해 2030년을 지속가능한 발전 목표(Sustainable Development Goals)로 하였다. 또한, 현재 물 산업은 빠르게 성장하고 있으며, 2016년 세계경제포럼(World Economic Forum) 의장 클라우스 슈밥(Klaus Schwab)부터 주창된 제4차 산업혁명로 인해 현재 물 산업의 패러다임 또한 급속히 변화하고 있다. 이는 컴퓨터를 기반으로 하는 CPS(Cyber Physical System) 및 DT(Digital Twin) 연계 분석방식의 혁신을 일컫는다. 2002년경에 DT의 기본개념이 제시되었고, 2006년경에는 Embedded System에서의 DT와 같은 개념으로 CPS의 용어가 등장했다. DT는 현실세계에 존재하는 사물, 시스템, 환경 등을 S/W시스템의 가상공간에 동일하게 모사(Virtualization) 및 모의(Simulation)할 수 있도록 하고, 모의결과를 가상시스템으로 현실세계를 최적화 체계 구현 기술을 말한다. DT의 6가지 기능은 ① 실제 데이터(Live Data), ② 모사, ③ 분석정보(Analytics), ④ 모의, ⑤ 예측(Predictions), ⑥ 자동화(Automation) 이다. 또한, CPS는 대규모 센서 및 액추에이터(Actuator)를 가지는 물리적 요소와 이를 실시간으로 제어하는 컴퓨팅 요소가 결합된 복합시스템을 말한다. CPS는 물리세계에서 발생하는 변화를 감지할 수 있는 다양한 센서를 통해 환경인지 기능을 수행한다. 센서로부터 수집된 정보와 물리세계를 재현 및 투영하는 고도화된 시스템 모델들을 기반으로 사이버 물리공간을 인지·분석·예측할 수 있다. CPS의 6가지 구성요소는 ① 상호 운용성(Interoperability), ② 가상화(Virtualization), ③ 분산화(Decentralization), ④ 실시간(Real-time Capability), ⑤ 서비스 오리엔테이션(Service Orientation), ⑥ 모듈화(Modularity)이다. DT와 CPS는 본질적으로 같은 목적, 내용, 그리고 결과를 만들어내고자 하는 같은 종류의 기술이라고 할 수 있다. CPS 및 DT는 물리세계에서 발생하는 변화를 감지할 수 있으며, 토양-지하수 센서를 포함한 관측기술을 통해 환경인지 기능을 수행한다. 지하수 관측기술로부터 수집된 정보와 물리세계를 재현 및 투영하는 고도화된 시스템 모델들을 기반으로 사이버 물리공간 및 디지털 트윈 공간을 인지·분석·예측할 수 있다. CPS 및 DT의 기본 요소들을 실현시키는 것은 양질의 데이터를 모니터링할 수 있는 정확하고 정밀한 1차원 연직 프로파일링 관측기술이며, 이를 토대로 한 수자원 관련 빅데이터의 증가, 빅데이터의 저장과 분석을 가능하게 하는 플랫폼의 개발이다. 본 연구는 CPS 및 DT 기반 토양수분-지하수 관측기술을 이용한 지표수-지하수 연계, 지하수 순환 및 관리, 정수 운영 및 진단프로그램 개발을 위한 토양수분-지하수 관측장치를 지하수 플랫폼 동시성과 디지털 트윈 시뮬레이터 시스템 개발 방향으로 제시하고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.145-151
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• 2009

Recently, the rapid development of GIS technology has made it possible to handle a various data associated with spatially hydrological parameters with their attribute information. Therefore, there has been a shift in focus from lumped runoff models to distributed runoff models, as the latter can consider temporal and spatial variations of discharge. This research is to evaluate the feasibility of GIS based distributed model using radar rainfall which can express temporal and spatial distribution in actual dam watershed during flood runoff period. K-DRUM (K-water hydrologic & hydaulic Distributed flood RUnoff Model) which was developed to calculate flood discharge connected to radar rainfall based on long-term runoff model developed by Kyoto- University DPRI (Disaster Prevention Research Institute), and Yondam-Dam watershed ($930km^2$) was applied as study site. Distributed rainfall according to grid resolution was generated by using preprocess program of radar rainfall, from JIN radar. Also, GIS hydrological parameters were extracted from basic GIS data such as DEM, land cover and soil map, and used as input data of distributed model (K-DRUM). Results of this research can provide a base for building of real-time short-term rainfall runoff forecast system according to flash flood in near future.

• Science of Emotion and Sensibility
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• v.26 no.4
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• pp.103-114
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• 2023

Augmented reality (AR) and virtual reality (VR) differ fundamentally, with AR overlaying computer-generated information onto the real world in a nonimmersive way. Despite extensive research on cybersickness in VR, its occurrence in AR has received less attention (Vovk et al., 2018). This study examines cybersickness and discomfort associated with AR usage, focusing on the impact of content intensity and exposure time. Participants viewed 30-minute racing simulation game clips through AR equipment, varying in racing speed to alter content intensity. Cybersickness was assessed subjectively using the Simulator sickness questionnaire (SSQ; Kennedy et al., 1993). Findings revealed a progressive increase in cybersickness with longer exposure, persisting even after removing the AR equipment. Contrarily, content intensity did not significantly influence cybersickness levels. Analysis of the SSQ subscales revealed higher oculomotor (O) scores compared to nausea (N) and disorientation (D), suggesting that discomfort primarily stemmed from oculomotor strain. The study highlights distinct differences in user experience between AR and VR, specifically in subjective responses.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.625-634
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• 2003

More than a decade after its initial proposal, deployment of IP Multicast has been limited due to the problem of traffic control in multicast routing, multicast address allocation in global internet, reliable multicast transport techniques etc. Lately, according to increase of multicast application service such as internet broadcast, real time security information service etc., overlay multicast is developed as a new internet multicast technology. In this paper, we describe an overlay multicast protocol and propose fast join mechanism that considers switching of the tree. To find a potential parent, an existing search algorithm descends the tree from the root by one level at a time, and it causes long joining latency. Also, it is try to select the nearest node as a potential parent. However, it can't select the nearest node by the degree limit of the node. As a result, the generated tree has low efficiency. To reduce long joining latency and improve the efficiency of the tree, we propose searching two levels of the tree at a time. This method forwards joining request message to own children node. So, at ordinary times, there is no overhead to keep the tree. But the joining request came, the increasing number of searching messages will reduce a long joining latency. Also searching more nodes will be helpful to construct more efficient trees. In order to evaluate the performance of our fast join mechanism, we measure the metrics such as the search latency and the number of searched node and the number of switching by the number of members and degree limit. The simulation results show that the performance of our mechanism is superior to that of the existing mechanism.

• The Korean Journal of Financial Management
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• v.6 no.1
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• pp.31-62
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• 1989

By using deterministic dynamic models, we observe the behavior of the foreign exchange rate of a small open economy with rational expectation formation and different restrictions on the international economic integrations. First, an economy connected to the world by purchasing power parity and uncovered interest parity is studied in the next section. In both sections, financial assets available in the economy are domestic money and bonds. Stocks are added as a financial instrument in the next section, and real capital accumulation is also taken into account. Furthermore, the economy concerned there is fairly autonomous, and not directly governed by either purchasing power parity or uncovered interest parity. The expectation formation used throughout the whole paper is complete perfect foresight, which is the certainty version of rational expectation and free from any forecast errors. It is found that upon monetary expansion the short run depreciation of the foreign exchange rate is a fairly robust result regardless of the degree of the international economic integration, while it is not true for fiscal expansion. The expectation on the long run state significantly affects the short run response of the exchange rate. All of our models postulate that the current account should be balanced eventually. As the result, the short run behavior of the exchange rate is affected by the expectation on the long run balance and may well be a blend of the traditional flow view and modem asset view. The initial overshooting of the exchange rate is easily observed even in the fairly autonomous economy Furthermore, the initial overshooting is not reduced over time, but augmented for some time before it is eventually eliminated. As long as we maintain rational expectaion, introducing time delay in the adjustment of the foreign goods price to the foreign exchange rate does not make much difference.

• Journal of Intelligence and Information Systems
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• v.18 no.4
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• pp.43-57
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• 2012

To enhance the competitive advantage in a constantly changing business environment, an enterprise management must make the right decision in many business activities based on both internal and external information. Thus, providing accurate information plays a prominent role in management's decision making. Intuitively, historical data can provide a feasible estimate through the forecasting models. Therefore, if the service department can estimate the service quantity for the next period, the service department can then effectively control the inventory of service related resources such as human, parts, and other facilities. In addition, the production department can make load map for improving its product quality. Therefore, obtaining an accurate service forecast most likely appears to be critical to manufacturing companies. Numerous investigations addressing this problem have generally employed statistical methods, such as regression or autoregressive and moving average simulation. However, these methods are only efficient for data with are seasonal or cyclical. If the data are influenced by the special characteristics of product, they are not feasible. In our research, we propose a forecasting framework that predicts service demand of manufacturing organization by combining Case-based reasoning (CBR) and leveraging an unsupervised artificial neural network based clustering analysis (i.e., Self-Organizing Maps; SOM). We believe that this is one of the first attempts at applying unsupervised artificial neural network-based machine-learning techniques in the service forecasting domain. Our proposed approach has several appealing features : (1) We applied CBR and SOM in a new forecasting domain such as service demand forecasting. (2) We proposed our combined approach between CBR and SOM in order to overcome limitations of traditional statistical forecasting methods and We have developed a service forecasting tool based on the proposed approach using an unsupervised artificial neural network and Case-based reasoning. In this research, we conducted an empirical study on a real digital TV manufacturer (i.e., Company A). In addition, we have empirically evaluated the proposed approach and tool using real sales and service related data from digital TV manufacturer. In our empirical experiments, we intend to explore the performance of our proposed service forecasting framework when compared to the performances predicted by other two service forecasting methods; one is traditional CBR based forecasting model and the other is the existing service forecasting model used by Company A. We ran each service forecasting 144 times; each time, input data were randomly sampled for each service forecasting framework. To evaluate accuracy of forecasting results, we used Mean Absolute Percentage Error (MAPE) as primary performance measure in our experiments. We conducted one-way ANOVA test with the 144 measurements of MAPE for three different service forecasting approaches. For example, the F-ratio of MAPE for three different service forecasting approaches is 67.25 and the p-value is 0.000. This means that the difference between the MAPE of the three different service forecasting approaches is significant at the level of 0.000. Since there is a significant difference among the different service forecasting approaches, we conducted Tukey's HSD post hoc test to determine exactly which means of MAPE are significantly different from which other ones. In terms of MAPE, Tukey's HSD post hoc test grouped the three different service forecasting approaches into three different subsets in the following order: our proposed approach > traditional CBR-based service forecasting approach > the existing forecasting approach used by Company A. Consequently, our empirical experiments show that our proposed approach outperformed the traditional CBR based forecasting model and the existing service forecasting model used by Company A. The rest of this paper is organized as follows. Section 2 provides some research background information such as summary of CBR and SOM. Section 3 presents a hybrid service forecasting framework based on Case-based Reasoning and Self-Organizing Maps, while the empirical evaluation results are summarized in Section 4. Conclusion and future research directions are finally discussed in Section 5.

• Hwankyungkyoyuk
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• v.7 no.1
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• pp.46-87
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• 1994

Our country has been consuming a huge amount of energy in the course of industrialization and its demand is expected to increase enormously in the future. However, the deposits of energy resources are so limited that the settlement of energy problem comes up the essential subject. To solve the energy problem, it is requested that new resources to gain energy stably should be developed and also energy should be economized and used effectively. The effective use of energy and an the wisdom of economy in energy are requested to everybody and these things should be habitualized from very young age through education. Nevertheless, almost every school in our country hasn’t been concerned about energy education. Even though they have a concern, they are very short of the energy education materials and the quality of the materials is not so good. Therefore it is very meaningful to the settlement of energy problem of the country to make the students who will lead our country to make the students who will lead our country in the future realize the seriousness of energy problem and to provide them the necessary knowledge and methods to solve this problem so that they practice those things in everyday life. Having these necessities, this research, supported by The Korea Energy Management Corporation(KEMCO), was performed for 8 months from April 17, 1994 to December 17, 1994. Many peoples participated in this study such as 30 staffs of researchers and authors, 5 staffs of photographers and illustrators, and 3 VCR program producers developing an energy education material set for middle school students that includes a printed material for student, a diskette for computer simulation, a teacher's guidebook, VCR material and its guidebook. The following main development direction was established : First, the material for student should be consisted of units that let students know the seriousness of energy problem. Second, the focus should be put on the necessary method and practice to economize energy actually in real life based on the basic knowledge learned in elementary school. Third, material for student should be consisted of modules to be student activity-oriented teaching-learning rather than lecture-oriented one. The activity, to maximize student's interests, should be presented in various forms such as experiments, investigation, play, data interpretation, computer simulation, visits, expression and appreciation, etc. To develop the energy education materials for middle school students, a research plan was made first. After literature review about domestic and foreign energy education materials, several research trips home and abroad, and discussion meetings, the basic theory of energy education such as the principle, objective, contents, teaching-learning method, and evaluation method was established. Material for student was developed through the following procedures : The activities in the existing energy education materials were analysed and were divided into four categories related to energy using places of home, school, community, and country, and which were again divided into three categories related to time of past, present, and future, Considering these division, nine modules which are structure units of material for student were chosen, Each module comprises 2-4 activities. Totally 31 activities were designed in this way. The syllabi were made out for each activity and writing was asked for to experts related to each activity after several discussions and revision. To complement the draft, another several discussions and revision were also made on it and then pictures and illustrations were asked for. All these procedures complete the material for student, titled ; Energy Inquiry of Middle School Students', which totals 129 pages and is all in color. As the manuscript of material for student was fixed, writing for teacher's guidebook was asked for to the same writers. The draft of teacher's guidebook was also complemented through the several concentrated works and discussions. Teacher's guidebook focused on the teaching-learning principle and methods of energy education and on the concrete instruction cases for effective instruction of material for student. It is organized with two parts : the one is 'general outline' which introduces theoretical contents and the other is 'details' which are practically helpful to teaching-learning. It is totally 131 pages including both 'general outline' and 'details'. The VCR material and its guidebook consist of contents that cultivate the good attitude trying to economize energy and raise student's interests with a purpose of strong motivation to recognize the necessity of economy and practice it. After establishing development direction of VCR material through discussion meetings and research trips, its script was made by relevant experts. Then the script was also reviewed two times. The drafted VCR material made by a video material developing expert was examined and modified by previews twice. After completion of VCR material, the VCR guidebook was made. All these procedures led to the development of VCR material which runs 20 minutes in VHS type. The VCR guidebook shows a production purpose of the program, structure of contents, evaluation methods, and contents of the program in detail to give help to instructors when they use this VCR material, When these energy education materials are used, it is desirable that the VCR material should be presented first to induce student's motive, and then material for student is introduced Since the material for student is composed of activity-oriented modules and each module is independent one another in general, and each activity is, too. the necessary module or activity can be chosen and utilized in any order according to school or class conditions. This energy education materials will contribute to the development of student's ability to solve energy problem in everyday life and teacher's ability to teach the fundamental knowledge and method in solving energy problem.