• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.4
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• pp.185-194
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• 2010

In this paper, we propose an application layer-based vertical handover management protocol, called multihoming RTP (mhRTP), for real-time applications with seamless mobility across heterogeneous wireless access networks. The proposed multi-homing RTP provides a soft handover by utilizing multiple available wireless access network interfaces simultaneously. The newly available path is dynamically added to the ongoing session by the mhRTP session manager. Also the decision making of QoS-improving or QoS-guaranteed handover is possible based on the estimation of available bandwidth in each candidate network. The performances of the proposed mhRTP have been analyzed through a series of simulations on OPNET network simulator. From the performance analysis, we confirmed that the proposed mhRTP can provide QoS-guaranteed vertical handover with efficient session managements.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.89-97
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• 2011

Traditional quality control for manufacturing or service sector is not suitable for the quality control of a project as the project is one-time task constrained by time, cost, and quality. To meet the internal and external customers' requirements, quality costs approach to the project will be effective. Hence, we propose PONC (price of nonconformance) estimation procedure and a mathematical model, which are focused on activity-based prevention in the execution step and warranty step of EPLC (extended project life cycle). This procedure and model will help project manager develop preventive action plan for project quality costs minimization from nonconformance risk activities and PONC estimates information.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.171-174
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• 2006

A large number of service providers in countries all over the world have established GNSS reference station networks in the last years and are using network software today to provide a correction stream to the user as a routine service. In current GNSS network processing, all the geometric related information such as ionospheric free carrier phase ambiguities from all stations and satellites, tropospheric effects, orbit errors, receiver and satellite clock errors are estimated in one centralized Kalman filter. Although this approach provides an optimal solution to the estimation problem, however, the processing time increases cubically with the number of reference stations in the network. Until now one single Personal Computer with Pentium 3.06 GHz CPU can only process data from a network consisting of no more than 50 stations in real time. In order to process data for larger networks in real time and to lower the computational load, a federated filter approach can be considered. The main benefit of this approach is that each local filter runs with reduced number of states and the computation time for the whole system increases only linearly with the number of local sensors, thus significantly reduces the computational load compared to the centralized filter approach. This paper presents the technical aspect and performance analysis of the federated filter approach. Test results show that for a network of 100 reference stations, with the centralized approach, the network processing including ionospheric modeling and network ambiguity fixing needs approximately 60 hours to process 24 hours network data in a 3.06 GHz computer, which means it is impossible to run this network in real time. With the federated filter approach, only less than 1 hour is needed, 66 times faster than the centralized filter approach. The availability and reliability of network processing remain at the same high level.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4D
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• pp.451-457
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• 2008

Establishing realistic bus service coverage is needed to build optimum city bus line networks and reasonable bus service coverage areas. The purposes of this study are understanding the characteristics of the present walking time and marginal walking time of small-medium cities and constructing an ANFIS (Adaptive Neuro-Fuzzy Inference System) model to estimate the marginal walking time for certain age and income. The cities of Masan, Chongwon and Jinju are selected for study cities. The 80 percentile of present walking time of bus users of these cities are 10.2-11.1 minutes, thus the values are greater than the 5 minutes of the maximum walking time in USA and the marginal walking times of 21.1-21.8 minutes are much greater. An ANFIS model based on pulled data of the cities are constructed to estimate the marginal walking time of small-medium cities. Analyzing the relationship between marginal walking time and age/income by using the model, the marginal walking time decreases as the age increases, but is near constant from the age of 25 to 35. And the marginal walking time is inversely proportional to the income. In comparing the surveyed and the estimated values, as the statistics of coefficient of determination, MSE and MAE are 0.996, 0.163, 0.333 respectively, it may be judged that the explainability of the model is very high. The technique developed in this study can be applied to other cities.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.32-39
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• 2018

Repairing timing and the extended service life with repairing are very important for cost estimation during operation. Conventionally used model for repair cost shows a step-shaped cost elevation without consideration of variability of extended service life due to repairing. In the work, RC(Reinforced Concrete) Column is considered for probabilistic evaluation of repairing number and cost. Two mix proportions are prepared and chloride behavior is evaluated with quantitative exterior conditions. The repairing frequency and cost are investigated with varying service life and the extended service life with repairing which were derived from the chloride behavior analysis. The effect of COV(Coefficient of Variation) on repairing frequency is small but the 1st repairing timing is shown to be major parameter. The probabilistic model for repairing cost is capable of reducing the number of repairing with changing the intended service life unlike deterministic model of repairing cost since it can provide continuous repair cost with time.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.12
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• pp.996-1001
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• 2005

Recently, with the development of service robots and with the new concept of ubiquitous world, the position estimation of mobile objects has been raised to an important problem. As pre-liminary research results, some of the localization schemes are introduced, which provide the relative location of the moving objects subjected to accumulated errors. To implement a real time localization system, a new absolute position estimation method for a mobile robot in indoor environment is proposed in this paper. Design and implementation of the localization system comes from the usage of active beacon systems (based upon RFID technology). The active beacon system is composed of an RFID receiver and an ultra-sonic transmitter: 1. The RFID receiver gets the synchronization signal from the mobile robot and 2. The ultra-sonic transmitter sends out the traveling signal to be used for measuring the distance. Position of a mobile robot in a three dimensional space can be calculated basically from the distance information from. Three beacons and the absolute position information of the beacons themselves. In some case, the mobile robot can get the ultrasonic signals from only one or two beacons, because of the obstacles located along the moving path. Therefore, in this paper, as one of our dedicated contribution, the position estimation scheme with less than three sensors has been developed. Also, the extended Kalman filter algorithm is applied for the improvement of position estimation accuracy of the mobile robot.

• Journal of the Korean Institute of Gas
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• v.25 no.3
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• pp.9-15
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• 2021

In this paper, a study on the construction of a knowledge base based on natural language processing and the design of a chemical substance estimation system for the development of a knowledge service for a real-time sensor information fusion detection system and symptoms of contact with chemical substances in industrial sites. The information on 499 chemical substances contact symptoms from the Wireless Information System for Emergency Responders(WISER) program provided by the National Institutes of Health(NIH) in the United States was used as a reference. AllegroGraph 7.0.1 was used, input triples are Cas No., Synonyms, Symptom, SMILES, InChl, and Formula. As a result of establishing the knowledge base, it was confirmed that 39 symptoms based on ammonia (CAS No: 7664-41-7) were the same as those of the WISER program. Through this, a method of establishing was proposed knowledge base for the symptom extraction process of the chemical substance estimation system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.1
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• pp.1-10
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• 1989

The stress history of a bridge is different depending on the characteristic of traffic flow. Because the flow is varied with vehicle type, weight and headway time etc., statistical analysis in bridges is necessary to estimate the history by traffic flow. By applying the statistical analyses in fracture mechanics, the remaining service life of the structure can be estimated. In this paper, 1)the statistical analysis of vehicle type, weight and headway time etc. to analysis randomness of traffic flow, 2)measuring and analysis of stress history of a real bridge, 3)reappearance of stress history by Monte-Carlo Simulation using constitution ratio of vehicle type, weight and headway time as probabilitic variable, 4)comparision of the calculated and modelled stress history, 5)calculation of reduction factor, 6)comparision of frequency of stress range depending on span length etc. were performed. From the results, the basic modelled stress history which is necessary for the method of estimation of the remaining service life of the structure could be suggested.

• Journal of Home Health Care Nursing
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• v.7 no.1
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• pp.58-72
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• 2000

This study was an attempt to encourage the development of a rehabilitation delivery system and programs as a substitute service for hospitalization on the case of car accident patients, such as hospital based home health care nursing services. Various substitute services for hospitalization are required to curtail the length of stay for inpatients who were hospitalized with car accident compensation insurance. It focused on developing an estimation an early discharge day for car accident inpatients based on detailed statements of treatment for 111 inpatients who were hospitalized at the General Hospital in 1997. This study had four specific purposes as follows. First. to find out the utilization of medical services. Second, to estimate the time of early discharge and income increasing effect based on early discharge for those patients. Third, to identify the factors affecting total medical expenditure and the length of stay for those inpatients. Forth, to figure out the need of utilizing home health care nursing service for accident patients. In order to analyze the length of stay and medical expenditure for inpatients who were hospitalized due to car accidents, the authors conducted micro- and macro-analysis of medical and medical expenditure records. Micro-analysis was done by nominal group discussion of 4 expertise with the critical criteria, such as a decrease in the amount of treatment after surgery, treatments, tests, drugs and changes in the test consistency, drug methods, vital signs, start of ROM exercise, doctor's order, patient's outside visiting ability, and stable conditions. In addition to identifying variables affecting medical expenditure, and the length of stay and income effect due to early discharge day, the data was analyzed with a multiple regression analysis and linear regression analysis model by SPSS-PC for windows and Excell program. Results of this study were as follows. First. the mean length of stay was 50.3 days. whereas the mean length of stay due to early discharge was 34.3 days at the hospital. The estimation of time of early discharge depended on the length of stay. The longer the length of stay, the longer the length of time of early discharge : for instance a length of stay under 10 days was estimated as correlating to a mean length of stay of 6.6 days and early discharge of 6.5. The mean length of stay was 217.4 days and the time of early discharge was 110.1 respectively. The mean medical expenditure per day was found to be 169.085 Won and the mean medical expenditure per day showed negative linear trends according to the length of stay at the hospital. The estimation results of the income effect due to being discharged 16 days early was around 2,244,000 won per bed. However. this sum does not represent the real benefits resulting from early discharge, but rather the income increasing amount without considering medical prime cost in the general hospital. Therefore, further analysis is required on the cost containments and benefits as turn over rate per bed as the medical prime costs. The length of stay was most significant and was positive to the total medical expenditure, as expected. Surgery and patient's residential area was also an important variable in explaining medical expenditure. The level of complications was the most significant variable in explaining the length of stay. There was a high level for need a home health care nursing service which further supports early discharge for accident patients. In addition, when the patient was discharged. they needed follow up care for complications suffered during the car accident. $86.8\%$ of discharged patients responded that they needed home health services after early discharge. From these research findings, the following suggestions have been drawn. Strategies on a health care delivery system must be developed in order to focus on the consumer's needs and being planned for 21 century health policy in Korea. Community based intermediate facilities or home health care should be developed for rehabilitation services as a substitute for hospitalization in order to shorten the length of stay would be. A hospital based home health care nursing service. it would be available immediately to utilize by patients who want rehabilitation services as a substitute for hospitalization with the cooperation of car insurance companies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.134-143
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• 2000

A train performance simulation (TPS) software is a computer program that simulates the operation of a train system over a specified railway route and it is widely used in railroad operation and research applications. Numerical and graphical results from the simulation software, which is developed in this study, provide information on such performance variables as travel time. running speed, energy consumption at a specific time interval and in overall service time as the train moves along the route. Three types of input data are required for a computer simulation: track information, train information, and running conditions. The simulation of train performance starts with several simple mathematical models including train configuration. traction efforts, running resistance. and braking requirements. Based on the basic specifications of Korean High Speed Railway, System. this study, puts a focus on the estimation and assessment of train performance comparing. the specific train configurations of KEST20/11. CPLE20/10. PROP20/10, which are proposed from the previous G7 projects.