• Proceedings of the KOR-KST Conference
• /
• 2007.02a
• /
• pp.228-235
• /
• 2007

• Journal of Positioning, Navigation, and Timing
• /
• v.10 no.4
• /
• pp.263-269
• /
• 2021

The carrier-based differential global navigation satellite system (CD-GNSS) has been garnering significant attention as a promising technology for unmanned vehicles for its high accuracy. The CD-GNSS systems to be used for safety-critical applications should provide a certain level of integrity. The integrity of these systems must be analyzed under various conditions, including fault-free and satellite fault conditions. The systems should be able to detect the faults that can cause large biases on the user position errors and quantify the integrity risk by computing the protection level (PL) to protect the user against the faults that are left undetected. Prior work has derived and investigated the PL for the fault-free condition. In this study, the integrity of the CD-GNSS system under the fault condition is analyzed. The position errors caused by the satellite's fault are compared with the fault-free PL (PL_H0) to verify whether the integrity requirement can be met without computing the PLs for the fault conditions. The simulations are conducted by assuming the ephemeris fault, and the position errors are evaluated by changing the size of the ephemeris faults that missed detection. It was confirmed that the existing fault monitors do not guarantee that the position error under the fault condition does not exceed the PL_H0. Further, the impact of the faults on the position errors is discussed.

• Journal of Biosystems Engineering
• /
• v.33 no.5
• /
• pp.348-354
• /
• 2008

Egg grading is determined by exterior and interior quality. Among the evaluation methods for the egg quality, a candling method is common to identify eggs with cracked shells and interior defects. But this method is time-consuming and laborious. In addition, practically, it is challenging to detect hairline and micro cracks. In this study, an on-line inspection system based on acoustic resonance frequency analysis was developed to detect hairline cracks on eggshells. A roller conveyor was used to transfer eggs along one lane to the impact position where each of eggs rotated by the roller was excited with an impact device at four different locations on the eggshell equator. The impact device was consisted of a plastic hammer and a rotary solenoid. The acoustic response of the egg to the impact was measured with a small condenser microphone at the same position as the impact device was installed. Two acoustic parameters, correlation coefficient for normalized power spectra and standard deviation of peak resonant frequencies, were used to detect cracked eggs. Intact eggs showed relatively high correlations among the four normalized power spectra and low standard deviations of the four peak resonant frequencies. On the other hand, cracked eggs showed low correlations and high standard deviations as compared to the intact. This method allowed a crack detection rate of 97.6%.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.402-408
• /
• 2021

Vehicle engineering analysis in the event of an accident caused by a car built on mechanical design has not been investigated in-depth but relies on the subjective experience knowledge of the investigator. This study analyzed the correlation between the speed, progress, steering, and braking before impact, which is consistent with the final stop position, by drawing a site situation chart using the CAD (CAD) program and repeating 250 crashes using the PC-Crash program. The following situations were investigated: lower impact velocity; greater impact speed of the vehicle, which is not affected significantly by the departure angle; higher vehicle speed, such as the effective impact velocity, after the impact; higher vehicle speed; and lower vehicle speed. (Ed note: I am unsure what you are saying here. It appears contradictory and not a complete sentence. Please check the changes.)The simulation results of this study identified the process of returning to the magnetic progression lane after recognizing the opposite porter while Mighty was carried out on the uphill left-curve section in a position that crossed the center line, and the collision of the porter's front left side, pushing the porter in the right diagonal direction and making the front stop towards approximately 11 o'clock.

• 한국전산유체공학회:학술대회논문집
• /
• 2002.05a
• /
• pp.164-170
• /
• 2002

Numerical analysis of the flowfield around a 50-meter class airship is performed to determine the optimal position for the airspeed probe installation. The turbulent flow around the hull with gondola is analyzed to examine the characteristics of the data measured by the probe attached to the gondola, and they turned out to show the nonlinear relation between the freestream and measured angles of attack and be influenced by the Reynolds number. New position of the hull nose was proposed and the effect of various factors on the flowfield around the nose was also examined. The analysis with a panel method showed that the effect of empennage was negligible, and the effect of gondola and boundary layer thickness had also little impact. It was shown that the freestream angle of attack would be the only independent variable for the probe position around the hull nose in constructing the calibration matrix.

• Asia Marketing Journal
• /
• v.17 no.3
• /
• pp.33-51
• /
• 2015

This study investigates which variables most effectively influence the positioning strategy of a brand. In addition, we test the connection between the positioning strategy of the brand and loyalty. Finally, we explore how brand experience effects the relationship between brand position and brand loyalty. To this end, this study employs the street-intercept method to collect data on consumers' perception of home appliances in Japan and conducts structural equation modeling analysis to test our hypotheses. Specifically, we find that assessments of product, service, and image have a significant impact on a brand's position which, in turn, drives brand loyalty. In addition, brand experience seems to moderate the relationship between service and brand positioning effectiveness. We also find that price promotions negatively affect brand loyalty. The research provides a consumer-centered, experiential view of how firms can develop strategies to more effectively position brands and increase loyalty among their customers. These results help both academics and practitioners to better understand how consumers assess a brand's position in the marketplace.

• Composites Research
• /
• v.27 no.4
• /
• pp.141-145
• /
• 2014

This paper presents a structural health monitoring method using piezoelectric paint sensor designed for an impact sensor. The piezoelectric paint sensor can be flexibly deposited onto most structural surfaces in a thin form of the paint, and measure impact signals without any external device such as a power amplifier. In this study, a composite plate having four zones coated with piezoelectric paint was used for impact monitoring test. The sensitivity of the piezoelectric paint sensor was obtained by measuring the output voltages against the impact force. In addition to the sensitivity measurement, the impact position has been also estimated by comparing the output signals of the paint sensors when the impact occurs on the specimen.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.453-456
• /
• 2009

Impact resistance of shape memory alloy hybrid composite(SMAHC) plates were experimentally investigated. Shape memory alloy(SMA) have large failure strain and failure stress and can absorb large strain energies through phase transformation. SMA wires were embedded in composite plates to improve their weak impact resistance. Tensile tests of SMA wires were performed at various temperature to investigate their thermo-mechanical properties. Low-Velocity impact tests of several types of composite plates with SMA/Al/Fe were performed. Embedding SMA wires was most effective to improve impact resistance of composite plates. The effects of SMA position on impact resistance were also investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.205-210
• /
• 1997

The analysis of the free vibrations of a circular cylindrical shell with a logitudinal, interior rectangular plate is performed. The natural frequencies and the mode shapes of the combined shells are experimentally obtained by impact testing using an impact hammer and an accelerometer. The effects of the position of the plate on the frequencies and mode shapes of the combined system are examined. The experimental results are compared with a finite element analysis and show good agreement.

• International Journal of Computer Science & Network Security
• /
• v.22 no.3
• /
• pp.389-395
• /
• 2022

This quantitative study explored the extent to which convenience enhances professional development (PD) online. The sample of the study consisted of 421 teachers and supervisors. Findings evinced that convenience stimulated online PD. Another salient finding is the absence of significant differences among participants' responses concerning position and gender. Nonetheless, a significant difference exists in the variable of teaching experience. Teachers with more than 26-year experience were motivated to use online PD, which evidently could be attributed to the convenience they had over teachers with fewer years of experience.