• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.10 no.2
• /
• pp.1-8
• /
• 2011

Traffic congestion is a source of significant economic and social costs in urban areas. Intelligent Transportation Systems (ITS) are a promising means to help alleviate congestion by utilizing advanced sensing, computing, and communication technologies. This paper proposes and investigates a basic and advanced ITS framework Advanced Traveler Information System (ATIS) using wireless Vehicle to Roadside (Centralized ATIS model: CA model) and Vehicle to Vehicle (DeCentralized ATIS model: DCA model) communication and assuming an ideal communication environment in the typical $6{\times}6$ urban grid traffic network. Results of this study indicate that an ATIS using wireless communication can save travel time given varying combinations of system characteristics: traffic flow, communication radio range, and penetration ratio. Also, all tested metrics of the CA and DCA models indicate that the system performance of both models is almost identical regardless of varying traffic demand and penetration ratios. Therefore, DCA model can be a reasonable alternative to the fixed infrastructure based ATIS model (CA model).

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.6
• /
• pp.195-201
• /
• 2017

As of 2016, the total traffic usage of handicapped people were 24.8%. Buses (25.6%) have the highest rate of travel, with the exception of "walking (33.5%)" as the main means of transportation for these handicapped people. Therefore, the Seoul Metropolitan Government expanded the low-floor bus, which is a means of transportation for the underbelly, to 30% by 2015, but the satisfaction level of mobility improvement of the underbelly was only 2% To 55%. In fact, increasing the percentage of low-floor buses is merely a superficial solution, and there are many restrictions on solving fundamental problems with limited budgets. Therefore, in this study, we use statistical analysis R, with a simple data manipulation and visualization function, to grasp the living area and life pattern of handicapped people in Seoul city.

• Journal of Korean Public Health Nursing
• /
• v.17 no.2
• /
• pp.203-211
• /
• 2003

The purpose of this study was to investigate the degree of satisfaction in using rehabilitation exercise rooms in public health centers. A total of 100 subjects were participated in the study who were clients of rehabilitation exercise rooms in two public health centers in one city of Kyunggi Do, Korea. Data were collected from March 1 to 30, 2003 using questionnaire. The data were analyzed using SPSS/PC computer program. The result are as follows : 1. The mean age of subjects was 62.6 years old, and men constituted $67.0\%$ of the participants. Most participants $(64\%)$ were in the middle socioeconomic status, and $(65\%)$ of subjects was diagnosed as stroke. 2. Regarding the source of information about rehabilitation exercise room in public health center, $56.0\%$ obtain information from colleagues or neighbors, and for most participants the time required to travel to rehabilitation exercise room was less than 30min on foot. Among rehabilitation services, Taping therapy $(53.0\%)$ was most frequently used among participants, 3. Sum of all satisfaction score was $71.10(\pm6.60,\;range:\;1-90)$ showed higher level of satisfaction. Cost, reliability, and kindness were main factors that affect the degree of satisfaction among participants. 4. Twenty-four percent of the respondents utilized clinic services in the health centers, and $27.4\%$ stoped rehabilitation services from hospitals and/or clinics due to high cost. 5. In the use of rehabilitation exercise room was positively correlated to age (r=.214, p<0.05) and disease duration(r=.241. p<0.05).

• Journal of Korean Society of Forest Science
• /
• v.107 no.2
• /
• pp.158-165
• /
• 2018

Reach-average velocity prediction in steep mountain streams is important for understanding fluvial processes and practical applications of erosion control in mountain streams. little studies have been conducted in reach-average velocity, but hydraulic researches have been carried out to examine the relationship between discharge and reach-average velocity in torrent reaches using a relatively large amount of discharge data. In this study, a total of 87 data were measured in 8 torrent reaches. Salt-dilution method was used to estimate discharge. Reach-average velocity was calculated from harmonic mean of travel time that were measured by salt-dilution technique. In order to exlpore the hydraulic relation, both discharge and velocity were non-dimensionalized by using $D_{50}$, $D_{84}$, ${\sigma}_{pro}$ and $IPR_{90}$. It also indicated that ${\sigma}_{pro}$ and $IPR_{90}$ were good variables as roughness height for develop the relationship between non-dimensional discharge and velocity in mountain streams. Generally, reach-average velocity could increase exponentially as discharge increases.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.11a
• /
• pp.156-157
• /
• 2005

Gas hydrate is ice-like crystalline lattice, formed at appropriate temperature and pressure, in which gas molecules are trapped. It is worldwide popular interesting subject as a potential energy. In korea, a seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. In this paper, we had conducted numerical and physical modeling experiments for seismic properties on gas hydrate with field data which had been acquired over the East sea in 1998. We used a finite difference seismic method with staggered grid for 2-D elastic wave equation to generate synthetic seismograms from multi-channel surface seismic survey, OBC(Ocean Bottom Cable) and VSP(Vertical Seismic Profiling). We developed the seismic physical modeling system which is simulated in the deep sea conditions and acquired the physical model data to the various source-receiver geometry. We carried out seismic complex analysis with the obtained data. In numerical and physical modeling data, we observed the phase reversal phenomenon of reflection wave at interface between the gas hydrate and free gas. In seismic physical modeling, seismic properties of the modeling material agree with the seismic velocity estimated from the travel time of reflection events. We could easily find out AVO(Amplitude Versus Offset) in the reflection strength profile through seismic complex analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.599-603
• /
• 2003

This paper present an error compensation system and On-Machine Measurement(OMM) system for improving the machining accuracy of ultra-precision lathe. The Fast-Tool-Servo(FTS) driven by a piezoelectric actuator is applied for error compensation system. The controller is implemented on the 32bit DSP for feedback control of piezoelectric actuator. The control system is designed to compensates three kinds of machining errors such as the straightness error of X-axis slide, the thermal growth error of the spindle. and the squareness between spindle and X-axis slide. OMM is preposed to measure the finished profile of workpiece on the machine-tool using capacitive sensor with highly accurate ruby tip probe guided by air bearing. The data acquisition system is linked to the CNC controller to get the position of each axis in real-time. Through the experiments, it is founded that the thermal growth of spindle and tile squareness error between spindle and X-axis slide influenced to machining error more than straightness error of X-axis slide in small travel length. These errors were simulated as a sinusoidal signal which has very low frequency and the FTS could compensate the signal less than 30 m. The implemented OMM system has been tested by measuring flat surface of 50 mm diameter and shows measurement error less than 400 mm

• Advances in aircraft and spacecraft science
• /
• v.4 no.4
• /
• pp.353-369
• /
• 2017

Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. This includes aircraft, buildings and bridges. Flutter occurs as a result of interactions between aerodynamic, stiffness, and inertia forces on a structure. In an aircraft, as the speed of the flow increases, there may be a point at which the structural damping is insufficient to damp out the motion which is increasing due to aerodynamic energy being added to the structure. This vibration can cause structural failure, and therefore considering flutter characteristics is an essential part of designing an aircraft. Scientists and engineers studied flutter and developed theories and mathematical tools to analyze the phenomenon. Strip theory aerodynamics, beam structural models, unsteady lifting surface methods (e.g., Doublet-Lattice) and finite element models expanded analysis capabilities. Periodic Structures have been in the focus of research for their useful characteristics and ability to attenuate vibration in frequency bands called "stop-bands". A periodic structure consists of cells which differ in material or geometry. As vibration waves travel along the structure and face the cell boundaries, some waves pass and some are reflected back, which may cause destructive interference with the succeeding waves. This may reduce the vibration level of the structure, and hence improve its dynamic performance. In this paper, for the first time, we analyze the flutter characteristics of a wing with a periodic change in its sandwich construction. The new technique preserves the external geometry of the wing structure and depends on changing the material of the sandwich core. The periodic analysis and the vibration response characteristics of the model are investigated using a finite element model for the wing. Previous studies investigating the dynamic bending response of a periodic sandwich beam in the absence of flow have shown promising results.

• Journal of the Korean Geophysical Society
• /
• v.5 no.3
• /
• pp.165-174
• /
• 2002

Seismic velocity and attenuation coefficient of the rocks under the broad-band earthquake observatories of the Korea Meteorological Administration have been measured in the laboratory by using very high frequency seismic waves. Estimated P velocities of the rocks range from 3.2 km/s to 5.6 km/s, depending on the rock type, mineral, and weathering, while, the attenuation coefficients vary from 0.06 to 4.3 db/kHz-m. It seems that P velocities is inversely proportional to the attenuation coefficients of the rocks. Average travel-time delays of the broad-band stations seem to be related with the measured P velocities in the laboratory.

• Geophysics and Geophysical Exploration
• /
• v.6 no.2
• /
• pp.95-100
• /
• 2003

In this study, we developed reflection tomography inversion algorithm using Straight Ray Technique (SRT) which can calculate travel time easily and fast for complex geological structure. The inversion process begins by setting the initial velocity model as a constant velocity model that hat only impedance boundaries. The inversion process searches a layer-interface structure model that is able to explain the given data satisfactorily by inverting to minimize data misfit. For getting optimal solution, we used Gauss-Newton method that needed constructing the approximate Hessian matrix. We also applied the Marquart-Levenberg regularization method to this inversion process to prevent solution diverging. The ability of the method to resolve typical target structures was tested in a synthetic salt dome inversion. Using the inverted velocity model, we obtained the migration image close to that of the true velocity model.

• Journal of Convergence for Information Technology
• /
• v.7 no.3
• /
• pp.127-137
• /
• 2017

Sally Potter's movie, Orlando is a bold re-make of Virginia Woolf's classic novel, Orlando: A Biography, in which an English nobleman survives 400 years - as a man and then a woman. This paper focuses on a study of the film of Orlando in light of the feministic view. In Woolf's gender-bending, time-traveling novel, Orlando, Woolf probes the ideology of patriarchal society through an androgynous persona. Sally Potter's adroit revision of Woolf's novel not only duplicates Woolf's Orlando but it also catches Woolf's feminism by using cinematic expertise. The film is incredibly true to Woolf's spirit. The most explicit changes were structural so the storyline was simplified. Thus Orlando gives us a license to travel freely from a man to a woman. In short, Orlando is not about feminism but the unity and harmony of male and female.