• Journal of Advanced Navigation Technology
• /
• v.10 no.1
• /
• pp.7-12
• /
• 2006

In this paper, we investigated performance for 5.8GHz dedicated short range communication system using OFDM which will be applied to Intelligent transportation system services. The maximum speed of a vehicle in DSRC channel is very fast as 180km/h, so a service time is very short to serve a various traffic information if hand-off is not occurred. Therefore higher bit rate is required to proved advanced and intelligent service to the drivers of various vehicle and the data transmission rate of the next generation DSRC system if being promoted over 10Mbps. The signals received in Racian channel have been simulated using the computer simulator. For performance improvement, BCH coding scheme are adopted.

• Journal of the Korean Society of Combustion
• /
• v.19 no.1
• /
• pp.39-44
• /
• 2014

A short reaction mechanism for premixed $CH_4/CHF_3/Air$ flames was developed with a reduction method of the combined application of simulation error minimization (SEM) which included connectivity method and principal component analysis. It consisted of 43 species and 403 elementary reactions at the condition of less than 5% of maximum error. The calculation time operated with a short mechanism was over 5 times faster than one with a detailed reaction mechanism. Good agreement was found between the flame speeds calculated by the short reaction mechanism and those by the detailed reaction mechanism for the entire range of $CHF_3/CH_4$ mole ratios and equivalence ratios. In addition excellent agreements were determined for the profiles of temperature, species concentration, and the production rates of the various species. So the short reaction mechanism was able to accurately predict the flame structure for premixed $CH_4/CHF_3/Air$ flames.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.7
• /
• pp.1186-1192
• /
• 2016

This paper proposes techniques to diagnose short-circuit faults of both the diodes and power FET in switching mode power supply (SMPS) by using a simple analog tester. The diodes in full-bridge rectifier, power FET, switching transformer, and some sensors are modelled with resistor. The total resistance value measured at the input terminal of a SMPS is analyzed when the short-circuit faults of diodes in a full bridge rectifier or power FET are occurred. The short-circuit faults of one or two diodes in a full bridge rectifier, power FET, and both the diodes in a full bridge rectifier and power FET can be detected by a range of total resistance, which is measured by the analog tester. Through experiments, the theoretical analysis for total resistance under short-circuit faults can be verified.

• Journal of Advanced Navigation Technology
• /
• v.27 no.4
• /
• pp.453-456
• /
• 2023

Fighter jets employ guided missiles equipped with seekers to counter enemy air threats. Short range guided missiles(SRM) usually carry infrared(IR) seekers and are used to engage targets within visual range. On the other hand, medium range guided missiles(MRM) often utilize radio frequency(RF) seekers to engage targets beyond visual range. Medium range guided missiles do not activate their seekers until they reach the detection range of the seeker, and the aircraft's radar guides them for a certain distance. This guidance method is called Missile Data Link(MDL), and it can be implemented in either one-way or two-way communication modes, depending on the missile's communication system. In this paper, we discuss MDL based on these two communication modes, along with the integration of RADAR, mission computers, and guided missiles.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2001.11a
• /
• pp.324-327
• /
• 2001

In this paper, a 24GHz FMCW radar system which measures the range and the relative velocity of a vehicle in close range is described. The intended ranging accuracy is 15cm and a possible system concept to achieve this objective is presented. The VCO nonlinearity correction method using a reference delay-line and the data extrapolation algorithms based on AR(autoregressive) model are applied. The implemented system shows relatively satisfactory results in ranging accuracy.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.27 no.1
• /
• pp.38-47
• /
• 2007

The initiation of fatigue cracks in a simulated aircraft structure with a series of rivet holes was detected by acoustic emission(AE), then the crack length was determined by surface acoustic wave(SAW) technique. With the initiation and growth of fatigue cracks, AE events increased intermittently to form a stepwise incremental curve of cumulative AE events whereas the crack length increased more or less monotonically. With the SAW technique employed, the crack sizing for 13 different cracks including some short cracks was performed. With the reference to the measurement by traveling microscope, cracks in the range of $1{\sim}8mm$ long were reliably sized by the SAW technique. Although it was impossible to size the short fatigue cracks in the range shorter than 1 mm, the SAW technique still appeared practically useful for a range of crack lengths often found in aircraft structures.

• The Journal of Korean Physical Therapy
• /
• v.30 no.3
• /
• pp.90-95
• /
• 2018

Purpose: To investigate the relationship between gross motor capacity and neuromuscular function in children with cerebral palsy (CP) through a short-term intensive intervention. Methods: Twenty-four children younger than 6 years of age (17 boys, 7 girls, mean $age{\pm}standard$ deviation, $42.71{\pm}14.43months$) who were diagnosed with CP underwent short-term intensive treatment for 8 weeks. An evaluation of gross motor function capacity using the gross motor function measure (GMFM-66 and GMFM-88) was performed to measure muscle strength, selective motor control (SMC), and spasticity, factors related to neuromusculoskeletal function. Changes in spasticity, strength, range of motion, selective motor function, and exercise intensity scores were evaluated in terms of the gross motor function classification system (GMFCS) and ages. Results: The GMFM-88 and GMFM-66 scores significantly increased, by $4.32{\pm}4.04$ and $2.41{\pm}1.51%$, respectively, following the 8-week intervention. The change in the GMFM-66 score did not reflect a statistically significant difference in the GMFCS level. However, there was a statistically significant difference in the GMFM-88 score change in individuals at GMFCS Level III, the strength and spasticity of subjects at GMFCS Levels I-II did not significantly differ (p<0.05). The changes in the GMFM-66 scores for strength, SMC, range of motion (ROM), and spasticity significantly differed according to age (p<0.05) in children aged 36 months and older. Overall, there was a statistically significant difference in strength, SMC, and spasticity (p<0.05) before and after intensive short-term treatment. Conclusion: The 8-week short-term intensive care intervention improved the motor function score of study participants, emphasizing the need for early intervention and additional research in this area.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.453-453
• /
• 2009

• Proceedings of the KSMRM Conference
• /
• 1996.10a
• /
• pp.18-18
• /
• 1996

• Proceedings of the Korean Ceranic Society Conference
• /
• 2000.10a
• /
• pp.64.1-64
• /
• 2000