• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.973-980
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• 2009

Many studies which have been done for efficient installation and management of wireless sensor networks (WSN) include energy savings, key managements and sensor deployments. Sensor deployment problem is one of the most important and fundamental issues among them in that the topic is directly related with the system cost and performance. In this paper, we suggest a sensor deployment scheme that reduces the system cost of WSN while satisfying the fundamental system requirements of connectivity between sensor nodes and sensing coverage. Using graphical information system(GIS) which contains region-dependent information related with connectivity condition, the initial positions of sensors in the procedure simulated annealing (SA) are determined. The GIS information helps in reducing system cost reduction not only at the initial deployment of SA but also at the final deployment of SA which is shown by computer simulations.

• Journal of the Korean Data and Information Science Society
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• v.26 no.2
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• pp.301-312
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• 2015

The purpose of this paper is to establish the epidemic model to explain the process of disease spread. The process of disease spread can be classified into two types: deterministic process and stochastic process. Most studies supposed that the process follows the deterministic process and established the model using the ordinary differential equation. In this article, we try to build the disease spread prediction model based on the SIR (Suspectible - Infectious - Recovered) model. we first estimated the model parameters using least squared method and applied to a deterministic model using ordinary differential equation. we also applied to a stochastic model based on Gillespie algorithm. The methods introduced in this paper are applied to the data on the number of cases of malaria every week from January 2001 to March 2003, released by Korea Centers for Disease Control and Prevention. As a result, we conclude that our model explains well the process of disease spread.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.293-298
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• 2007

The aged are faced with increasing risk for falls. The aged have more fragile bones than others. When falls occur, it is important to detect this emergency state because such events often lead to more serious illness or even death. A implementation of PDA system, for detection of emergency situation, was developed using 3-axis accelerometer in this paper as follows. The signals were acquired from the 3-axis accelerometer, and then transmitted to the PDA through a Bluetooth module. This system can classify human activity, and also detect an emergency state like falls. When the fall occurs, the system generates the alarm on the PDA. If a subject does not respond to the alarm, the system determines whether the current situation is an emergency state or not, and then sends some information to the emergency center in the case of an urgent situation. Three different studies were conducted on 12 experimental subjects, with results indicating a good accuracy. The first study was performed to detect the posture change of human daily activity. The second study was performed to detect the correct direction of fall. The third study was conducted to check the classification of the daily physical activity. Each test lasted at least 1 min. in the third study. The output of the acceleration signal was compared and evaluated by changing various postures after attaching a 3-axis accelerometer module on the chest. The newly developed system has some important features such as portability, convenience and low cost. One of the main advantages of this system is that it is available at home healthcare environment. Another important feature lies in its low cost of manufacture. The implemented system can detect the fall accurately, so it will be widely used in emergency situations.

• Journal of Navigation and Port Research
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• v.34 no.2
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• pp.105-110
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• 2010

The studies on automatic ship collision avoidance system, which have been carried out in the last 10 years, are facing on new situation due to newly developed high technology such as computer and other information system. It was almost impossible to make it used in real navigation field 3-4 years ago because of the absence of any tool to give other ship's information, however recently developed technology suggests new possibility. This study is carried out to develop the automatic ship collision avoidance support system which considers ship's manoeuvrability into it's collision avoidance algorithm. One of the important part in ship collision avoidance system is collision decision module which can calculate collision risk with other ships and act properly to avoid the situation. Many of previous researches are using present ship's dynamic data such as present speed, position and course to calculate collision risk. However when a ship commences avoidance action, the real situation is quite different with one that has been estimated by the ship's initial data due to the ship's manoeuvring characteristic. Therefore it is better to take into account ship's manoeuvring characteristic from the stage of collision decision in ship collision avoidance system. In this study, these effects are included in the developed system. The proposed system are verified its usefulness in numerical simulation environments.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.32-47
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• 1996

Systematic theoretical arm experimental studies have been performed to establish the methods of the hull form design, the optimum dimension selection and the resistance estimation for the displacement type super high-speed ships. In this study, theoretical hull form design method of the displacement type super high-speed ships has been developed first by the minimum resistance theory and the sectionally-varying hull form equation. Utilizing the established hull form design method, sixty(60) series hull forms have been prepared according to the systematic variations of the important design variables, and model tests were conducted for the sixty(60) series ship models. Finally, regression analyses have been performed for the results of model tests. It is considered that this is the first systematic and multi-purpose study in the world for the super high-speed ships. The study has been completed very successfully. The prepared computer program is now being actively utilized as an efficient tool for the design of the displacement type super high-speed ships.

• Journal of Service Research and Studies
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• v.5 no.1
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• pp.35-43
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• 2015

Regional comparative analysis for the variability of young man's employment indexes is important to unemployment or employment policy data of central and local government. Through the result of comparative analysis, central and local government can use differentiated policies for the regions and keep the efficiency for the application of detailed policy. In this study, based on economically active population survey data which consider economically active population rate, employment population rate and unemployment rate as typical employment indexes of young man, we analyzed the variability of these indexes by metropolitan cities and province regions using coefficient of variation. Also we proposed the largest index in variability of three employment indexes, and proposed the city and province region with the largest variability for each employment index.

• Journal of Service Research and Studies
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• v.2 no.2
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• pp.91-98
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• 2012

The emergence of new types of embedded computing devices and developments in wireless networking are broadening the domain of computing from the work place and home office to other facets of everyday life. This trend is expected to lead to a proliferation of Internet of Things (IoT) environments, in which inexpensive and interconnected computing devices are capable of supporting users in a range of tasks. Context-aware computing is a key source to develop such smart services. However, there are many challenges to enable services to be smart; Heterogeneous Computing Environments, Resource Limitations, Large Amount of Data Produced, and Different Requirements for Context Interpretation. Because of these challenges, there are difficulties in providing smart service by utilizing IoT devices. Currently, many researchers are conducting researches on mobile-computing based smart service development and provisioning and network infrastructure for interconnected IoT devices. Still, there are some limitations on developing core technologies for IoT computing based smart service development. In order to remedy this situation, this thesis presents a reusable framework that provides unique and noble features which are required in developing advanced context-aware IoT applications.

• Journal of Service Research and Studies
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• v.2 no.2
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• pp.45-51
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• 2012

U-healthcare is real-time monitoring of personal biometric information using by portable devices, home network and information and communication technology based healthcare systems, and fused together automatically to overcome the constraints of time and space are connected with hospitals and doctors. As u-healthcare gives health service in anytime and anywhere, it becomes to be a new type of medical services in patients management and disease prevention. In this paper, recent changes in prevention-oriented care is analyzed in becoming early response for Healthcare Information System by requirements analysis for technology development trend. According to the healthcare system, PACS, OCS, EMR and emergency medical system, U-healthcare is presenting the design of a patient-centered integrated client system. As the relationship between the meaning of the terms is used in the ontology, information models in the system is providing a common vocabulary with various levels of formality. In this paper, we propose an ontology-based system for patient-centered services, including the concept of clustering to clustering the data to define the relationship between these ontologies for more systematic data.

• Journal of Service Research and Studies
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• v.2 no.2
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• pp.23-33
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• 2012

For recent years, there have been considerable changes in the employment rate of the service industry and its relative ratio. These changes vary depending on the region whether it is Seoul metropolitan region or not. According to main results of this article, the average of employment rate in the service industry has been highest in the Seoul metropolitan region. And the changes by period of the employment-rate in the service industry have increased continuously for all the time in the Seoul metropolitan region whereas they have varied in other regions. Also the relative ratio of employment rate in the service industry to total employment rate has been more higher in Seoul metropolitan region and Gangwon region than other regions, and also the changes by period of the relative ratio have more increased in these two regions than other regions. Finally, comparing metropolitan city regions with do regions for the average of employment rate in the service industry or the relative ratio of it, they have more higher in metropolitan city regions than do regions, whereas the changes by period of them have varied with each other regions.

• Journal of Service Research and Studies
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• v.7 no.4
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• pp.69-81
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• 2017

Smart work refers to enhancing the efficiency of work by utilizing smart devices. Smart work improves business productivity by improving business productivity of companies, reducing costs, but there is a threat to various information protection. To operate telecommuting, mobile office, and smart work center, hardware and software are needed to support various network resources, servers, and platforms. As a result, there are many vulnerabilities to security and information protection that protect information resources. In this paper, we analyze the smart work environment for smart work service and analyze vulnerability for smart work information protection through analysis of IOS27001 and KISA-ISMS. We have developed requirements for information protection requirements for users and service providers. We have developed a solution for information security protection for smart work environments such as common parts, mobile office, telecommuting, and smart work center for security threats and weaknesses per smart work type.