• Journal of Energy Engineering
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• v.27 no.4
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• pp.103-110
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• 2018

In this paper, we introduce evaluation method of time series prediction model with new approach of Mean Absolute Percentage Error(hereafter MAPE) and Symmetric Mean Absolute Percentage Error(hereafter sMAPE). There are some problems using MAPE and sMAPE. First MAPE can't evaluate Zero observation of dataset. Moreover, when the observed value is very close to zero it evaluate heavier than other methods. Finally it evaluate different measure even same error between observations and predicted values. And sMAPE does different evaluations are made depending on whether the same error value is over-predicted or under-predicted. And it has different measurement according to the each sign, even if error is the same distance. These problems were solved by Maximum Mean Absolute Percentage Error(hereafter mMAPE). we used the absolute maximum of observed value as denominator instead of the observed value in MAPE, when the value is less than 1, removed denominator then solved the problem that the zero value is not defined. and were able to prevent heavier measurement problem. Also, if the absolute maximum of observed value is greater than 1, the evaluation values of mMAPE were compared with those of the other evaluations. With Beijing PM2.5 temperature data and our simulation data, we compared the evaluation values of mMAPE with other evaluations. And we proved that mMAPE can solve the problems that we mentioned.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.434-445
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• 2020

In this study, the minimization of harbor oscillation using permeable breakwater was applied to the actual harbor and investigated an effect of minimization by computer simulation in order to take into account the water quality problems and measures of harbor oscillation by infragravity waves at the same time. The study site is Mukho harbor located at East coast of Korea that harbor oscillation has been occurred frequently. The infragravity waves obtained by analyzing the observed field data for five years focused on the distribution between wave periods of 40 s and 70 s and wave heights in less than 0.1 m was 94% of analyzing data. The target wave periods was 68.0 s. The most effective method of minimization of harbor oscillation by infragravity waves was to install a detached permeable breakwater with transmission coefficient of 0.3 on the outside harbor and replace some area of the vertical wall in the harbor with wave energy dissipating structure to achieve a reflectivity of 0.9 or less. The amplitude reduction rate of this method shown in 27.4%. And the effect of the difference in transmission coefficient of permeable breakwater on the reduction rate of the amplitude was not significant.

• Journal of Internet Computing and Services
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• v.24 no.4
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• pp.57-64
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• 2023

The ROK military faces a significant challenge in its vigilance mission due to demographic problems, particularly the current aging population and population cliff. This study demonstrates the crucial role of the 4th industrial revolution and its core artificial intelligence algorithm in maximizing work efficiency within the Command&Control room by mechanizing simple tasks. To achieve a fully developed military surveillance system, we have chosen multi-object tracking (MOT) technology as an essential artificial intelligence component, aligning with our goal of an intelligent and automated surveillance system. Additionally, we have prioritized data visualization and user interface to ensure system accessibility and efficiency. These complementary elements come together to form a cohesive software application. The CCTV video data for this study was collected from the CCTV cameras installed at the 1st and 2nd main gates of the 00 unit, with the cooperation by Command&Control room. Experimental results indicate that an intelligent and automated surveillance system enables the delivery of more information to the operators in the room. However, it is important to acknowledge the limitations of the developed software system in this study. By highlighting these limitations, we can present the future direction for the development of military surveillance systems.

• Journal of the Economic Geographical Society of Korea
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• v.10 no.1
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• pp.44-63
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• 2007

The purpose of this study is to propose mining processes in the large trip-transaction database of the Metropolitan Seoul area and to analyze the spatial characteristics of travel behavior. For the purpose. this study introduces a mining algorithm developed for exploring trip patterns from the large trip-transaction database produced every day by transit users in the Metropolitan Seoul area. The algorithm computes trip chains of transit users by using the bus routes and a graph of the subway stops in the Seoul subway network. We explore the transfer frequency of the transit users in their trip chains in a day transaction database of three different years. We find the number of transit users who transfer to other bus or subway is increasing yearly. From the trip chains of the large trip-transaction database, trip patterns are mined to analyze how transit users travel in the public transportation system. The mining algorithm is a kind of level-wise approaches to find frequent trip patterns. The resulting frequent patterns are illustrated to show top-ranked subway stations and bus stops in their supports. From the outputs, we explore the travel patterns of three different time zones in a day. We obtain sufficient differences in the spatial structures in the travel patterns of origin and destination depending on time zones. In order to examine the changes in the travel patterns along time, we apply the algorithm to one day data per year since 2004. The results are visualized by utilizing GIS, and then the spatial characteristics of travel patterns are analyzed. The spatial distribution of trip origins and destinations shows the sharp distinction among time zones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1318-1324
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• 2010

Recently, U-Healthcare is receiving attentions as a research for reducing the manpower, time in treatment, and etc. Although fundamental technologies, such as sensing, measuring, and etc. are sufficiently investigated. However, Technologies of IT/Medical convergence, which graft IT technologies to medical area, are still in germ. For this, we present a novel healthcare system, which can be applied to the middle sized medical environment, such as private hospital, home, or etc., by means of pre-verified technologies and the expert system. There exist IT element technologies are sufficiently developed in the fields, such as network, database or etc. due to the remarkable developments in IT technologies, and the healthcare is a mission-critical environment. Therefore, it is important not only to investigate novel approaches but also to utilize verified technologies for the U-Healthcare solution. Presented solution provisions automated medical services based on expert system by utilizing the measured data, such as body fat, blood pressure, blood glucose, and etc., in order to provide convenient treatment environment to doctors and nurses. In addition, since people, who do not have medical knowledge, can self-diagnose themselves, it is expected to cut medical costs in various areas. Especially, since each devices communicate with each other through standardized Bluetooth technology, Presented healthcare system is an extensible solution which can easily accept various medical devices. As a result of this, we can safely say that the self measurement and diagnosis services in U-Healthcare are now enhanced by reducing medical cost through our healthcare system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1237-1244
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• 2009

In this paper, we proposed a mobile phone payment system using light signal containing payment related information. The digicard system we proposed creates virtual mobile card such as credit numbers and the created information is loaded in mobile phone. The virtual card information should be changed to pulse signal by light signal devices of mobile phone and the specific digicard system reader is able to read light signal. In recent years, a mobile phone payment system has been developed in order to provide user's convenience. But the mobile phone payment system has problems such as the production costs and complex and large size. In order to solve the aforementioned problems, we proposed mobile phone payment system being implemented by updating software without additional hardware modules. Therefore it is possible to apply the proposed digicard system to all kinds of mobile phone. Also encryption module is implemented to solve the problem of the security and privacy. According to an aspect of the present invention, there is provided a mobile phone payment system using a light signal containing payment-related information, comprising: a mobile phone; a photo receiver: and a control server.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.51-56
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• 2016

In this paper, we propose an Arduino-based plant monitoring system. The proposed system is based on the Arduino platform, using an environmental sensor and a pressure sensor for measuring temperature, humidity and illuminance in order to monitor the state of the environment and the facilities of the plant. Monitoring data are transmitted to a ZigBee coordinator connected to a server through a radio frequency transceiver. When using a pressure sensor and the environment sensor data stored on the host server, checking the pressure in the environment of the plant and equipment is intended to report any alarm status to the administrator. Using a grid line-based key distribution scheme, the authentication node dynamically generates a data key to protect the monitoring information. Applying a ZigBee wireless sensor network does not require additional wiring for the actual implementation of a plant monitoring system. Possible working-environment monitoring of an efficient plant can help analyze the cause of any failure by backtracking the working environment when a failure occurs. In addition, it is easy to expand or add a sensor function using the Arduino platform and an expansion board.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.39-50
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• 2017

This study examined what leads to smartphone addiction by looking into personal, environmental, and smartphone characteristics, to identify their influences on the degree of addiction and changes in daily life. Therefore, surveys were conducted on college undergraduates, who get easily addicted to smartphones The study hypotheses were evaluated through a structural equation model on a total of 370 collected survey questionnaires Findings revealed: first, with reference to personal characteristics, the more competent and highly related one is, the more negatively influenced one is in getting addicted to smartphones. Second, as for environmental characteristics, the bigger the social impact is, the more positively influenced one is on smartphone addiction. Third, among the characteristics of a smartphone, the ubiquity showed a positive influence on smartphone addiction. Lastly, the degree to which one is addicted to a smartphone has(either positive or negative) on the changes in one's daily life. These results are not intended to blindly inhibit smartphone use by highlighting the negative aspects of smartphones, but are expected to serve as basic data to develop a preventative and remedial program based on the degree of smartphone addiction.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.4
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• pp.1-10
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• 2010

This present paper's goal is to show a virtual human agent's movement-data loci based on realistically limited perception data is human-like. To determine human-likeness of the movement-data loci, we consider interactions between two parameters: Realistically Limited Perception (RLP) data and Incremental Movement-Path data Generation (IMPG). That is to consider how the former (i.e., RLP), one of the simulated parameters of human thought or its elements dictates the latter (i.e., IMPG), one of the simulated parameters of human movement behavior. Mapping DB is a prerequisite for navigation in an agent system because it functions as an interface between perception and movement behavior. Although Hill et al. studied mapping DB methodology based on RLP, their research dealt only with a rendering camera's view point data. The agent system in this present paper was integrated with the Hill's mapping DB module and then the two parameters' interaction was considered on a military reconnaissance mission with unexpected enemy emergence. Movement loci that were generated by the agent and subjects were compared with each other. The agent system in this present research verifies that it can be a functional test bed for producing human-like movement-data loci although the human-likeness of agent is the result of a pilot test, determined by two parameters (RLP and IMPG) and only 30 subjects.

• Journal of the Economic Geographical Society of Korea
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• v.9 no.3
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• pp.379-395
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• 2006

The purpose of this study is to analyze the spatial characteristics of travel patterns and travel behaviors of transit users in the Metropolitan Seoul area. We apply the data mining techniques to explore the travel patterns of transit users from the T-money card database which has been produced over 10,000,000 transaction records per day. The database contains the information of locations and times of origin, transfer, and destination points for each transaction as well as the informations of transit modes taken via the transaction. We develop an data mining algorithm to explore traversal patterns from the enormous information. The algorithm determines the travel sequences of each passenger, and produce the volumes of support on each points (stops) of transportation networks in the Metropolitan Seoul area. In order to visualize the spatial patterns of travel demands for transit systems we apply GIS techniques, and attempt to investigate the spatial characteristics of travel patterns and travel demand. Subway stops located in the Gangnam area appear the highest peak for the travel origin and destination, while the CBD in the Gangbuk stands at the second position. Two or three sub-peaks appear at the densely populated residential areas developed as the high-rise apartment complex. Subway stations located along the Subway Line 2, especially from Guro to Samsung receive heavy travel demand (total support), while bus stops located at the CBD in the Gangbuk stands the highest travel demand by bus.