• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.5 s.51
• /
• pp.11-23
• /
• 2006

This paper evaluates the seismic response of multi-span prestressed concrete girder bridges typically found in the New Madrid Seismic Zone region of the central United States. Using detailed nonlinear analytical models and synthetic ground motion records for Memphis, TN, nonlinear response history analyses are performed for two levels of ground motion: 10% probability of exceedance (PE) in 50 years, and 2% probability of exceedance (PE) in 50 years. The results show that the bridge performance is very good fur the 10% PE in 50 years ground motion level. However, the performance for the 2% PE in 50 years ground motion is not so good because it results in highly inelastic behavior of the bridge. Impact between decks results in large ductility demands on the columns, and failure of the bearings that support the girders. It is found that making the superstructure continuous, which is commonly performed for reducing dead load moments and maintenance requirements, results in significant improvement in the seismic response of prestressed concrete girder bridges.

• IEIE Transactions on Smart Processing and Computing
• /
• v.1 no.2
• /
• pp.95-105
• /
• 2012

The widespread implementation of RFID in ubiquitous computing is constrained considerably by privacy and security unreliability of the wireless communication channel. This failure to satisfy the basic, security needs of the technology has a direct impact of the limited computational capability of the tags, which are essential for the implementation of RFID. Because the universal application of RFID means the use of low cost tags, their security is limited to lightweight cryptographic primitives. Therefore, EPCGen2, which is a class of low cost tags, has the enabling properties to support their communication protocols. This means that satisfying the security needs of EPCGen2 could ensure low cost security because EPCGen2 is a class of low cost, passive tags. In that way, a solution to the hindrance of low cost tags lies in the security of EPCGen2. To this effect, many lightweight authentication protocols have been proposed to improve the privacy and security of communication protocols suitable for low cost tags. Although many EPCgen2 compliant protocols have been proposed to ensure the security of low cost tags, the optimum security has not been guaranteed because many protocols are prone to well-known attacks or fall short of acceptable computational load. This paper proposes a remedy protocol to the flyweight RFID authentication protocol proposed by Burmester and Munilla against a desynchronization attack. Based on shared pseudorandom number generator, this protocol provides mutual authentication, anonymity, session unlinkability and forward security in addition to security against a desynchronization attack. The desirable features of this protocol are efficiency and security.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.3
• /
• pp.30-36
• /
• 2004

As fiber reinforced composite materials are widely used in aircraft, space structures and robot arms, the study on the non-destructive testing methods of the composite materials has become an important research area for improving their reliability and safety. In this paper, the AE signal analyzer with the resonance circuit to extract the specified frequency of the acoustic emission signal were designed and fabricated. The noise levels of the fabricated AE signal analyzer by the disturbance such as impact or mechanical vibration had a very small value comparable to those of the conventional AE signal analyzer. Also, the fabricated AE signal analyzer was proved to have about the same crack detection capabilities with the conventional AE signal analyzer under the static and dynamic tensile tests of the composite materials.

• Health Policy and Management
• /
• v.19 no.3
• /
• pp.1-26
• /
• 2009

Objectives : To identify target areas and set priorities among those areas identified for national quality evaluation. Methods : Target areas were identified from: i) analysis of the national health insurance claims data, mortality and prevalence data ii) various group surveys, including representatives from 22 medical specialty associations, 19 physician associations, QI staffs in hospital, civil organizations, and commissioners of Health Insurance Review and Assessment Service(HIRA) ⅲ) literature reviews and RAM(RAND/UCLA appropriateness method). The priority areas for national quality evaluation represented the full spectrum of health care and the entire life span. The criteria for selecting the priority areas were impact, improvability, and measurability. The priority areas were divided into three categories : short-term, mid-term, long-term. Results: Based on the group surveys and the data analysis, 46 candidates were selected as quality evaluation priority areas. 13 areas were selected as having a short-term priority areas: tuberculosis, community acquired pneumonia, stroke, ischaemic heart disease, diabetes, hypertension, chronic lower respiratory disease(asthma, chronic obstructive pulmonary disease), intensive care unit, emergency room, nosocomial infection, use of antibiotics, multiple medication and renal failure. This results suggested that we need to enlarge the target priority areas to the chronic diseases in short-term. Conclusions: The priority areas identified from the study will assist healthcare quality associated institutions as well as HIRA in selecting quality evaluation areas. It is required to develope and implement strategies for improving the quality of care within the next 5 years.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.2
• /
• pp.137-143
• /
• 2016

The fifth wheel coupler is a heavy automotive coupling structure which connects a tractor and a trailer used for heavy-duty trucks widely. It is subjected to various loads simultaneously such as rolling, pitching and yawing loads as well as coupling frictional and impact loadings. Most of existing couplers have been overdesigned and, therefore, it is necessary to reduce the dead weight to increase the fuel efficiency. The topology optimization was applied in order to find conceptual layout designs which could show major load paths and ribs locations, and then the size structural optimization was performed in order to determine the heights and thicknesses of coupler ribs with the predetermined various loading conditions for the development of a new slim coupler with a minimum weight and high enough strength and stiffness. As the results of the topology optimum design, an efficient new coupling structure for truck trailers was designed. The weight of the new fifth wheel coupler was reduced by 4.9 %, compared with the existing one, even though all strength requirements were satisfied. The fatigue test of the new coupler was performed with cyclic vertical loads (+78.4 to +235.2 kN) and horizontal loads (-91.2 to +91.2 kN) simultaneously at 1 Hz and the life of 2,000,000 cycles were achieved without failure.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.6
• /
• pp.490-497
• /
• 2017

The Main Landing Gear(MLG) of Rotary Wing Aircraft is an essential equipment in Landing System for pilot to perform a flight mission. It supports the fuselage at ground and absorbs the impact from the ground when landing, thereby, these functions sustain operational capability for pilot and crew. However, the A aircraft caused asymmetry and leakage hydraulic when it was stationed on the ground. Therefore, this paper summarizes pilot comments in operation which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.235-238
• /
• 2002

The successful completion of a construction project requires a thorough understanding of all stages and phases of the project, and enhanced through integration of design and construction during the pre-construction stage. Constructability is a major factor in measuring the success or failure of construction project. During the pre-construction stage, lack of construction knowledge integration in the planning and design process is a major factor that leads to constructability problems during the construction stage. this study is to find out such problems based on interview and questionnaire in the structure's work of High-Rise Office Buildings. The objective of this study is to Identify Impact aspect of the structure's work of High-Rise Office Buildings.

• Journal of Advanced Navigation Technology
• /
• v.15 no.5
• /
• pp.823-832
• /
• 2011

Recently, as the project becomes larger and the number of project increases by the information system integration in the public and financial sectors, it is necessary to have a proper plan to manage the information system project. There have been many researches about the project management, success elements and failure elements, but the research on the interrelation between project management areas leaves much to be desired. This research deduces the scope, schedule, quality, work force and risk as the project management areas from the preceding research and the questionnaire and interview with PM developers, information system builders and data processing experts. And, it analyzes the interrelation and the relative importance between management areas, classifies the progress of the management areas under plan, implementation and completion stage and presents the frame to evaluate the accomplishment of each progress.

• Journal of Korean Neurosurgical Society
• /
• v.54 no.6
• /
• pp.496-500
• /
• 2013

Objective : To evaluate the successful fusion rate in postmenopausal women with single-level anterior cervical discectomy and successful fusion (ACDF) and identify the significant factors related to bone successful fusion in pre- and postmenopausal women. Methods : From July 2004 to December 2010, 108 consecutive patients who underwent single-level ACDF were prospectively selected as candidates. Among these, the charts and radiological data of 39 women were reviewed retrospectively. These 39 women were divided into two groups : a premenopausal group (n=11) and a postmenopausal group (n=28). To evaluate the significant factors affecting the successful fusion rate, the following were analyzed : the presence of successful fusion, successful fusion type, age, operated level, bone mineral density, graft materials, stand-alone cage or plating with autologous iliac bone, subsidence, adjacent segment degeneration, smoking, diabetes mellitus, and renal disease. Results : The successful fusion rates of the pre- and postmenopausal groups were 90.9% and 89.2%, respectively. There was no significant difference in the successful fusion rate or successful fusion type between the two groups. In the postmenopausal group, three patients (10.8%) had successful fusion failure. In the postmenopausal group, age and subsidence significantly affected the successful fusion rate (p=0.016 and 0.011, respectively), and the incidence of subsidence in patients with a cage was higher than that in patients with a plate (p=0.030). Conclusion : Menopausal status did not significantly affect bone successful fusion in patients with single-level ACDF. However, in older women with single-level ACDF, the combination of use of a cage and subsidence may unfavorably affect successful fusion.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.9
• /
• pp.691-701
• /
• 2020

An actuator mixer design using convex optimization technique situation where the propulsion system of an electric VTOL UAV during vertical take-off and landing maneuvers is proposed. The attainable control set to analyze the impact from failure of each motor and propeller can be calculated and illustrated using the properties of the convex function. The control allocation can be defined as a convex function optimization problem to obtain an optimal solution in real time. The mixer is implemented using a convex optimization solver, and the performance of the control allocation methods is compared to the attainable control set. Finally, the proposed mixer is compared with other techniques with nonlinear sux degree-of-freedom simulation.