• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.1-6
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• 2014

This paper proposes a mobile content curation service to collect various online/offline publications. The company publishes one-time topic information to a broker server in advance and customer curates topic information on a mobile device by requesting it. The main characteristics of the proposed service are: it is based on request/response model rather than existing publish/subscribe model, can easily specify topic information by input string without QR code or audio recognition, and retrieves all of topic information anywhere anytime by storing it on mobile device. This service can be used for second screen campaign for TV and various online/offline events.

• Convergence Security Journal
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• v.17 no.5
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• pp.3-10
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• 2017

Standard Protocol Optimized for Resource-Constrained IoT Environment Constrained Application Protocol (CoAP) supports web-based communication between a sensor node in the IoT environment and a client on the Internet. The CoAP is a Request / Response model that responds to the client's CoAP Request message by responding with a CoAP Response message from the server. CoAP recommends the use of CoAP-DTLS for message protection. However, validation of the use of DTLS in the IoT environment is underway. We analyze CoAP and DTLS security mode, evaluate performance of secure channel creation time, security channel creation step time, and RAM / ROM consumption through Cooja simulator and evaluate the possibility of real environment application.

• Journal of the Korea Convergence Society
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• v.8 no.3
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• pp.23-30
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• 2017

OpenADR is a national standard communication protocol of demand response service. OpenADR uses XML message, called a payload, to support logical transaction of demand response service. For this purpose, OpenADR defines a XML element as transaction identifier which is called requestID. Unfortunately, OpenADR 2.0b profile specification describes some information about requestID but, it is not enough for understanding properly. Ambiguous definition of payload transaction makes vulnerabilities of implementing VEN & VTN and confuses mapping OpenADR 2.0b protocol into other smart grid protocols. Therefore, this paper redefines payload transaction to solve an ambiguous information of OpenADR 2.0b profile specification, proposes a model of analyzing payload transaction, and shows how to detect a payload transaction vulnerability in real-world.

• Journal of Navigation and Port Research
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• v.35 no.9
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• pp.735-740
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• 2011

It is necessary to develop the one stop system in order to protect our marine environment rapidly from oil spill accident. The purpose of this study is to develop real time database for oil spill prediction modeling and implement real time prediction modelling with ESI and server-client GIS based user interface. The existing oil spill prediction model cannot provide one stop information system for public and government who should protect sea from oil spill accident. The development of multi user based information system permits integrated handling of real time meteorological data from external ftp. A server-client GIS based model is integrated on the basis of real time database and ESI map to provide the result of the oil spill prediction model. End users can access through the client interface and request analysis such as oil spill prediction and GIS functions on the network as their own purpose.

• Proceedings of the Korea Association of Information Systems Conference
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• 1996.11a
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• pp.199-204
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• 1996

It is discussed how to determine the home location of idle vehicles in an AGVS with a loop guide path in a way of maximizing the request-call response probabilities for all demand. Optimal home position is selected by solving the simultaneous equations easily. Static positioning strategy is analyzed in which a single home position is allocated to which every vehicle is routed whenever it becomes idle. The cases of unidirectional guidepath is considered only. We provide a numerical example to illustrate the search algorithm developed for the case and compare the searched optimal solutions with the others.

• Journal of Navigation and Port Research
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• v.36 no.2
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• pp.105-112
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• 2012

In order to improve the existing S-57 standard, International Hydrographic Organization(IHO) has developed S-100 standard, a Universal Hydrographic Data Model(UHDM) expanded from ISO 19100 series standard to hydrographic area, and is in the process of its implementation. International Maritime Organization(IMO) has established CMDS based on e-Navigation strategy data standard as International Association of Lighthouse Authorities(IALA) established IHDM based on aids to navigation data standard and each data standard is linked with the S-100 standard. Fundamental concept and core principles of S-100 standard is suitable not only for the development of a wide range of hydrographic data and service production standard, including the next generation ENC, but also the development of product specification of non-hydrographic area. This study has examined the operation principle of S-100 standard and analyzed its implementation process as e-Navigation data in relation with ENC. It also noted the utilization of S-100 standard based e-Navigation and its potential effect via examining the development cases of S-100 standard-based product specification, such as nautical publication, ship reporting and pilot request, digital routing guide, tide and water level transmission and other important data cases of e-Navigation field.

• Industrial Engineering and Management Systems
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• v.6 no.2
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• pp.125-135
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• 2007

An automated guided vehicle (AGV) system is a group of collaborating unmanned vehicles which is commonly used for transporting materials within manufacturing, warehousing, or distribution systems. The performance of an AGV system depends on the dispatching rules used to assign vehicles to pickup requests, the vehicle routing protocols, and the home location of idle vehicles, which are called dwell points. In manufacturing and distribution environments which emphasize just-in-time principles, performance measures for material handling are based on response times for pickup requests and equipment utilization. In an AGV system, the response time for a pickup request is the time that it takes for the vehicle to travel from its dwell point to the pickup station. In this article, an exact dynamic programming algorithm for selecting dwell points in a tandem-loop multiple-vehicle AGV system is presented. The objective of the model is to minimize the maximum response time for all pickup requests in a given shift. The recursive algorithm considers time restrictions on the availability of vehicles during the shift.

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.57-64
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• 2016

In this paper, we propose the design of railway safety common data model to provide common transformation method for collecting data from railway facility fields to Real-time railway safety monitoring and control system. This common data model is divided into five abstract sub-models according to the characteristics of data such as 'StateInfoMessage', 'ControlMessage', 'RequestMessage', 'ResponseMessage' and 'ExtendedXXXMessage'. This kind of model structure allows diverse heterogeneous data acquisitions and its common conversion method to DDS (Data Distribution Service) format to share data to the sub-systems of Real-time railway safety monitoring and control system. This paper contains the design of common data model and its DDS Topic expression for DDS communication, and presents two kinds of data transformation case studied for verification of the model design.

• Journal of KIISE:Databases
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• v.31 no.4
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• pp.422-431
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• 2004

In recent years, different models in data delivery have been explored in mobile computing systems. Particularly, there were a lot of research efforts in the periodic push model where the server repetitively disseminates information without explicit request. However, average waiting time per data operation highly depends on the length of a broadcast cycle and different access pattern among clients may deteriorate the response time considerably. In this case, clients are preferably willing to send a data request to the server explicitly through backchannel in order to obtain optimal response time. We call the broadcast model supporting backchannel as hybrid broadcast. In this paper, we devise a new transaction processing algorithm(O-PreH) in hybrid broadcast environments. The data objects which the server maintains are divided into Push_Data for periodic broadcasting and Pull_Data for on-demand processing. Clients tune in broadcast channel or demand the data of interests according to the data type. Periodic invalidation reports from the server support maintaining transactional consistency. If one or more conflicts are found, conflict orders are determined not to violate the consistency(pre-reordering) and then the remaining operations have to be executed pessimistically. Through extensive simulations, we demonstrate the improved throughput of the proposed algorithm.

• Health Policy and Management
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• v.9 no.2
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• pp.95-117
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• 1999

The purposes of the study was to analysis the factors on the physicians' indemnity experience and indemnity on malpractice. Data was collected from mail interview for the physicians from August, to October in 1996. Questions were asked to the physician who selected with random sample(n=8.338) about the opinion of malpractice insurance. experience that he(she) have requested the indemnity from patience. context of experienced indemnity and demographic characteristics of physician and patience. Response rate is 37.5%(n=3,124). This study was analyzed in two levels' the first. influential factors on whether physician has experience of indemnity and the second. influential factors of indemnity among physicians who had experienced the indemnity. The major findings were as follows : 1. Logistic regression on whether physicians had experience of indemnity request was conducted. And it indicated that statistically meaningful variables of model 1 (about all physicians) were department of surgery, physicians who have intention of insurance fee, physician age and income, physicians who owned the hospitals and statistically meaningful variables of model 11 (about physicians who owned the hospital) were department of surgery and internal treatment. 2. Multiple regression on the influential factors on indemnity was conducted. And it showed that statistically meaningful variables in model 1 were method of malpractice quarrel(physician association), whether physician had malpractice, whether suit succeeded, physician age, average practice time and income and whether physician owned the hospital and statistically meaningful variables of model 11 were whether physician had malpractice, number of outpatient, number of beds. As the conclusion, the thesis was examined about the variables related with experience of indemnity and cost of malpractice. But in order to prevent malpractice and promote medical quality, the reasonable system to solve a malpractice have to settle and cost estimation on malpractice is essential. Therefore an advanced research is progressed with methodology to decide the indemnity bases.