• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.2A
• /
• pp.95-104
• /
• 2010

In wireless communication system, a variety of retransmission algorithms are used in order to improve the quality of service of users. But the system may be inefficient because retransmission algorithms operate independently with other layers. Also, the quality of service can be degraded due to the unnecessary retransmission of packets. To solve these problems, the study on the cross-layer retransmission schemes have been widely performed. However, in order to apply cross-layer retransmission schemes to wireless communication system, whether the performance of cross-layer retransmission schemes meets QoS requirements of each service class has to be verified. Thus, this paper proposes the mathematical model for analyzing the performance of the cross-layer retransmission schemes and derives both the suitable retransmission scheme and the optimal retransmission parameter on each service class. The proposed mathematical model selects the MCS level based on channel state information and The performance analysis is comparatively easy in case that HARQ, ARQ, and AMC schemes are combined. The proposed mathematical model also enables the analysis of the packet transmission delay. To utilize the analytical model, this paper derives the suitable retransmission scheme and the optimal retransmission parameter for delay sensitive services in WiMAX system. Also, the proposed analytical model can be used to analyze the performance of wireless communication system such as LTE and WLAN.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.4
• /
• pp.630-643
• /
• 2001

In this paper, the performance of a Multi-Carrier DS-CDMA system with Hybrid $SC/MRC- L_{c}/L$ diversity in the multipath Rayleigh fading environment is analyzed and compared with that of a Wideband DS-CDMA system. Each carriers of the number of the input diversity branches in the Multi-Carrier DS-CDMA system is L and among L, the branches of $L_c$ are chosen to be maximum-ratio-combined. And the diversity outputs are coherent-detected and despread by the correlator of each carrier. As the result, we have known that the structure of the Wideband DS-CDMA system with Hybrid $SC/MRC-L_{c}/L$ diversity reception becomes simple due to no synchronization of bit or phase and in terms of the error performance, the performance of Hybrid $SC/MRC- L_{c}/L$ diversity is better than that of selection diversity, but worse than that of MRC diversity. Moreover, the performance of a Multi-Carrier DS-CDMA system is better than that of a Wideband DS-CDMA system in multipath Rayleigh fading channel since Hybrid $SC/MRC- L_c/L$ diversity can obtain gain from each diversity branch. In case four carriers are used and required BER is $10^{-6}$ in wireless data communication, Hybrid SC/MRC-2/4 diversity can increase more 17 users than Hybrid SC/MRC-2/3 diversity because the better input branches can be selected through increase of input branches.

• Cartoon and Animation Studies
• /
• s.36
• /
• pp.643-667
• /
• 2014

Recently, shooting photographs have become highly popular among general public and been used by various media such as digital camera, mobile, and kiosk. We could find that users prefer to Funology which is combined by fun and hardware technology on emotional point of view. Shooting photographs attracts user participation and makes effect of design to expand. The goal of this study is to classify user actions in a electronic kiosk which includes digital photography function based on the perspective of Funology and to bulit user behaviors model. Therefore user group model will be defined, and then interaction design guidelines of shooting photographs will be proposed. For this research, first of all, the concepts of Funology and user interaction with taking photographs are classified to three types which is based on literature investigation. Secondly, "Phodosee" kiosk is examined with Funology design elements which have been categorized beforehand. Then user's behaviors which are shown their interaction with "Phodosee" kiosk are observed and analyzed using video ethnography based on Funology perspectives. Finally, four persona models are suggested based on user's behaviors as follows; 1) to avoid being taken photography, 2) to try to shoot photography, 3) to participate shooting photography and 4) to lead others to take photography. To summarize this study, effects and limitations of Funology design elements using digital photography are discussed and guideline is suggested to improve user experience design.

• Archives of design research
• /
• v.17 no.3
• /
• pp.353-362
• /
• 2004

This research has been done to evaluate the interior environmental factors in Gyungro-dang to suggest the advanced recommendations for them. For this research, the essential interior elements influencing on elderly's behavior were examined with the developed checklist, the lighting and color conditions of main hall at 14 facilities in Seoul area were analysed, and 124 subjects staying at Gyungro-dang were participated in questionaire survey for color preferences. Results showed that 1.The average installation rate of 39 items in checklist was 59%, the mandatory items such as accessible dimension were considered, but several items related to mobility and safety were not properly installed. Therefore not only guiding handrail and floor block to destination but also elimination of obstacles should be reconsidered. 2.The average of illuminances was 289 Lux dose to standard 300 Lux, but lighting quality was too low to support the activities of elderly users. The lighting control devices, combined lighting sources, and suitable lighting techniques should be applied for those facilities. 3.Most facilities were predominantly in warm colors in hue, medium or high value, low saturation, and natural atmosphere with similarity harmony. The color applications in those facilities were not functional, but similar as color preferences for the elderly except overall atmosphere. It is recommendable to include contrast harmony with classic or romantic mood.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.149-152
• /
• 2006

The usage increase of digital contents required solution for protection technology and interoperability of system. MPEG proposed MPEG-21 Multimedia Frameworks. MPEG-21 IPMP is standard that provides the means to enable digital item and rights information to be persistently managed and protected across networks and devices. In this paper, MPEG-21 IPMP based system to protect digital contents designed by four structures of license server, production server, consumption server, tool sewer. License sewer create rights information document using the XML-based REL about multimedia contents of users. Production server makes a digital item by packaging multimedia resource and metadata, which is combined by REL information and IPMP information of multimedia resource. Consumption server takes care of the functions of players that use digital item, and tool server was implement to transmit for missing tool that night occur in all procedures.

• Journal of KIISE:Computing Practices and Letters
• /
• v.5 no.5
• /
• pp.583-594
• /
• 1999

With the advance of VLSI and network technologies, it has now become a common practice to deploy a various forms of distributed computing environments. A study shows that a lot of network-aware computers are in an idle state for considerable amount of time depending on the types of users and time frames of the day. If we can take the full advantage of those idle computers, we can obtain the enormous combined processing power without further costly investment. In this paper, we present a distributed batch-processing system, called the Java Distributed Batch-processing System (JDBS), which allows us to execute CPU-intensive, independent jobs across a pool of idle workstations on top of extant distributed computing environments. Since JDBS is implemented using a Java programming language, it not only extends the scope of machine types that can be joined to the pool, but makes it a lot easier to build an entire system. Besides, JDBS is scalable and fault-tolerant due to its multi-cluster organization and intelligent strategies. A graphical user interface is also provided to facilitate the registration and unregistration, job submission, and job monitoring.

• KIPS Transactions on Software and Data Engineering
• /
• v.5 no.7
• /
• pp.319-326
• /
• 2016

Given the attributes of mobile apps that shorten the time to make purchase decisions while enabling easy purchase cancellations, usability can be regarded to be a highly prioritized quality attribute among the diverse quality attributes that must be provided by mobile apps. With that backdrop, mobile app developers have been making great effort to minimize usability hampering elements that degrade the merchantability of apps in many ways. Most elements that hamper the convenience in use of mobile apps stem from those potential errors that occur when GUIs are designed. In our previous study, we have proposed a technique to analyze the usability of mobile apps using user behavior logs. We proposes a technique to detect usability hampering elements lying dormant in mobile apps' GUI models by expressing user behavior logs with finite state models, combining user behavior models extracted from multiple users, and comparing the combined user behavior model with the expected behavior model on which the designer's intention is reflected. In addition, to reduce the burden of the repeated test operations that have been conducted by existing developers to detect usability errors, the present paper also proposes a mobile usability error detection automation tool that enables automatic application of the proposed technique. The utility of the proposed technique and tool is being discussed through comparison between the GUI issue reports presented by actual open source app developers and the symptoms detected by the proposed technique.

• Journal of Advanced Navigation Technology
• /
• v.17 no.5
• /
• pp.475-483
• /
• 2013

In this paper, the performances of modeling methods for combining corrections from multiple reference stations for network user were compared and analyzed. The longer the distance between reference station and user is, the more the GPS errors are decorrelated. Based on this point, multiple corrections from reference stations which is constituting a network should be combined properly to be applied for user observation to eliminate GPS errors. There are many widely used conventional modeling methods and they are applied for Compact Network RTK users and user position accuracy is predicted by using residual errors in observation of user. Compact Network RTK is a technique of generating corrections which was developed by Seoul National University. As a result, the horizontal and vertical accuracies were within about 5 cm and 7 cm respectively with 95 % probability for all conventional modeling methods. In addition, we analyzed condition for reference station constellation for modeling method using height information.

• Journal of Biomedical Engineering Research
• /
• v.40 no.5
• /
• pp.197-205
• /
• 2019

The existing Extracorporeal membrane oxygenation(ECMO) and Cardiopulmonary bypass system(CPB) have been developed and applied to various devices according to their respective indications. However, due to the complicated configuration and difficult usage method, it causes inconvenience to users and there is a risk of an accident. Therefore, smart all-in-one cardiopulmonary circulation device is being developed recently. The smart all-in-one cardiopulmonary assist device consists of a blood pump for cardiopulmonary bypass, a blood oxidizer for cardiopulmonary bypass, a blood circuit for cardiopulmonary bypass, and an artificial cardiopulmonary device. It is an integrated cardiopulmonary bypass device that can be used for a variety of purposes such as emergency, intraoperative, post-operative intensive care, and long-term cardiopulmonary assist, combined with CPB used in open heart surgery and ECMO used when patient's cardiopulmonary function does not work normally. The smart all-in-one cardiopulmonary assist device does not exist as a standard and international standard applicable to advanced medical devices. Therefore, in this study, we will refer to the International Standard for Blood Components, the International Standard for Blood, the Guideline for Blood Products, and prepare applicable performance and safety guidelines to help quality control of medical devices, and contribute to the improvement of the health of people. The guideline, which is the result of conducted a survey of the method of safety and performance test, is based on the principle of all-in-one cardiopulmonary aiding device, related domestic foreign standards, the status of domestic and foreign patents, related literature, blood pump(ISO 18242), blood oxygenator (ISO 7199), and blood circuit (ISO 15676) for cardiopulmonary bypass.The items on blood safety are as follows: American Society for Testing and Materials ASTM F1841-97R17), and in the 2010 Food and Drug Administration's Safety Assessment Guidelines for Medical Assisted Circulatory Devices. In addition, after reviewing the guidelines drawn up through expert consultation bodies including manufacturers / importers, testing inspectors, academia, etc. the final guideline was established through revision and supplementation process. Therefore, we propose guidelines for evaluating the safety and performance of smart all-in-one cardiopulmonary assist devices in line with growing technology.

• Journal of Convergence for Information Technology
• /
• v.9 no.4
• /
• pp.1-7
• /
• 2019

The medical environment, combined with IT technology, is changing the paradigm for medical services from treatment to prevention. In particular, as ICT convergence digital healthcare technology is applied to hospital medical systems, infrastructure technologies such as big data, Internet of Things, and artificial intelligence are being used in conjunction with the cloud. In particular, as medical services are used with IT devices, the quality of medical services is increasingly improving to make them easier for users to access. Medical institutions seeking to incorporate IoT services into cloud health care environment services are trying to reduce hospital operating costs and improve service quality, but have not yet been fully supported. In this paper, a patient information collection model from hospital IoT system, which has established a cloud environment, is proposed. The proposed model prevents third parties from illegally eavesdropping and interfering with patients' biometric information through IoT devices attached to the patient's body at hospitals in cloud environments that have established hospital IoT systems. The proposed model allows clinicians to analyze patients' disease information so that they can collect and treat diseases associated with their eating habits through IoT devices. The analyzed disease information minimizes hospital work to facilitate the handling of prescriptions and care according to the patient's degree of illness.