• Journal of The Korean Ophthalmological Society
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• v.59 no.12
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• pp.1122-1128
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• 2018

Purpose: To compare the measurements of the rebound tonometer (RT), Goldmann applanation tonometer (GAT) and noncontact tonometer (NCT) in patients who underwent penetrating keratoplasty (PKP), and to evaluate the reproducibility of the RT measurements. Methods: This study included 19 PKP eyes and 28 normal eyes. We compared the intraocular pressure (IOP) measurements of the GAT and NCT with the RT in both groups using Spearman's correlation analysis and the Wilcoxon signed-rank test. The IOP, as measured with an RT in each group, was assessed with respect to reproducibility using the intraclass correlation coefficient (ICC). Results: In normal eyes, there was no significant difference in the measurements obtained with the RT, GAT, and NCT (p > 0.050). In the patient group, the RT measurements were not significantly different from those of the GAT (p = 0.872), but they were significantly lower than those obtained with the NCT (p = 0.011). However, the RT measurements showed a relatively high correlation with those of the GAT and NCT (r = 0.770 and 0.879, respectively). The ICC of the RT was 0.986 for the PKP eye group and 0.961 for the normal eye group, both of which were highly reproducible. Conclusions: In PKP eyes, the measurements obtained with the RT showed a relatively high correlation with those of the GAT and NCT, and the repeatability of the RT measurements was high and similar to those for normal eyes. The RT can therefore be considered a useful method for measuring the IOP in PKP eyes.

• Smart Structures and Systems
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• v.17 no.6
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• pp.935-956
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• 2016

With the help of advanced image acquisition and processing technology, the vision-based measurement methods have been broadly applied to implement the structural monitoring and condition identification of civil engineering structures. Many noncontact approaches enabled by different digital image processing algorithms are developed to overcome the problems in conventional structural dynamic displacement measurement. This paper presents three kinds of image processing algorithms for structural dynamic displacement measurement, i.e., the grayscale pattern matching (GPM) algorithm, the color pattern matching (CPM) algorithm, and the mean shift tracking (MST) algorithm. A vision-based system programmed with the three image processing algorithms is developed for multi-point structural dynamic displacement measurement. The dynamic displacement time histories of multiple vision points are simultaneously measured by the vision-based system and the magnetostrictive displacement sensor (MDS) during the laboratory shaking table tests of a three-story steel frame model. The comparative analysis results indicate that the developed vision-based system exhibits excellent performance in structural dynamic displacement measurement by use of the three different image processing algorithms. The field application experiments are also carried out on an arch bridge for the measurement of displacement influence lines during the loading tests to validate the effectiveness of the vision-based system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.3
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• pp.1050-1060
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• 1996

Recently, attention has been paid to the flame diagnostic by noncontact methods which dose not deform the flame shape. One of them is a method which is using the radical luminous intensity. Generally, this diagnostic method using radical luminous has been investigated its reliability by applying to laminar flame. This study, however, investigated each radical luminous signals through stocastical analysis like auto-correlation, cross-correlation, phase and coherence which were acquired from measuring radical luminous intensity of OH, CH, $O_{2}$, radicals in turbulent diffusion flame. To compare radical luminous intensity in flame with temperature, ion current and concentration , radious distribution of each properties was investigated and considered. In radical luminous intensity, correlation in the reaction zone of flame was higher than in correlation in combusted gas zone. And radious distribution of radical luminous intensity was corresponded with radious distribution of temperature, ion current and concentration. The result of the study confirms that a radical luminous flame diagnosis is possible in the turbulent diffusion flame.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.61-68
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• 2020

Thermographic phosphor (TP) thermometry is a noncontact optical measurement method and has been applied in many fields such as combustion and heat transfer. However, due to the limitation of bonding technology and measurement method, most TP thermometry studies were conducted only on the air environment with water-soluble binders. In this paper, a temperature measurement technology in water using TP is proposed by coatings of manganese activated magnesium fluorogermanate (Mg4FGeO6:Mn4+, MFG) with Polydimethylsiloxane (PDMS). Four MFG-PDMS coatings with different thicknesses were prepared. The lifetime of MFG was not affected by the thickness of the coating as a result of the experiment and analysis of phosphor intensity using a photomultiplier tube. To measure the surface temperature field of an immerged body in water, a cylinder-type cartridge heater was coated with MFG doped PDMS. Transient surface temperature field was successfully measured even the initial temperature is higher than the boiling point of water.

• Safety and Health at Work
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• v.12 no.4
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• pp.496-504
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• 2021

Background: With the increasing demand for industrial robots and the "noncontact" trend, it is an appropriate point in time to examine whether risk assessments conducted for robot operations are performed effectively to identify and eliminate the risks of injury or harm to operators. This study discusses why robot accidents resulting in harm to operators occur repetitively despite implementing control measures and proposes corrective actions for risk assessments. Methods: This study collected 369 operator-injured robot accidents in Korea over the last decade and reconstructed them into the mechanism of injury, work being undertaken, and bodily location of the injury. Then, through the techniques of Systematic Cause Analysis Technique (SCAT) and Root Cause Analysis (RCA), this study analyzed the root and direct causes of robot accidents that had occurred. Causes identified included physical hazards and complex combinations of hazards, such as psychological, organizational, and systematic errors. The requirements of risk assessments regarding robot operations were examined, and three case studies of robot-involved tasks were investigated. The three assessments presented were: camera module processing, electrical discharge machining, and a panel-flipping robot installation. Results: After conducting RCA and comparing the three assessments, it was found that two-thirds of injury-occurring from robot accidents, causative factors included psychological and personal traits of robot operators. However, there were no evaluations of the identifications of personal aspects in the three assessment cases. Conclusion: Therefore, it was concluded that personal factors of operators, which had been overlooked in risk assessments so far, need to be included in future risk assessments on robot operations.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.35-41
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• 2014

A rotordynamic analysis is performed for a turbopump of 7 ton class liquid rocket engine considering bearing housing structural flexibility. Stiffness and damping characteristics of ball bearings and pump noncontact seals are reflected in a rotordynamic model. A dynamic model of bearing housing with lumped mass and stiffness is also applied to the rotordynamic analysis. Rotor critical speed and onset speed of instability are predicted from synchronous rotor mass unbalance response and complex eigenvalue analyses. The bearing housing structural flexibility effect on rotordynamic characteristics is investigated for both of bearing loaded and unloaded conditions respectively. From the numerical analysis, it is found that the effect of the housing structural flexibility significantly reduces the rotor critical speed and onset speed of instability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.7
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• pp.688-694
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• 2008

A rotordynamic analysis is performed for a high thrust class liquid rocket engine turbopump considering the dynamic characteristics of ball bearings and pump noncontact seals. Complex eigenvalue problems are solved to predict the rotating natural frequencies and damping ratios as a function of rotating speeds. Synchronous rotor mass unbalance response and time transient response analyses are also performed to figure out the rotor critical speed and the onset speed of instability. From the numerical analysis, it is found that the rear bearing stiffness is most important parameter for the critical speed and instability because the 1st mode is turbine side shaft bending mode. The pump seal effect on the critical speed is enlarged as the rear bearing stiffness decreases and the front bearing stiffness increases.

• Journal of Korean Society of Rural Planning
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• v.27 no.4
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• pp.43-54
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• 2021

This study analysed changes in rural tourism between before and after COVID-19 using LDA topic analysis. In order to understand the changes in rural tourism, blog data including the keyword 'Gochang-gun travel' was used. As a result of LDA topic analysis with blog data retrieved, the study found nine topics in 2019 and 2020. 2019 and 2020 are, generally, consistent in topics, but the three topics related to rural experiential tourism that appeared in 2019 did not appear in 2020. In 2020, three new topics emerged: Beach vacations and campings. New travel activities of noncontact with other people(Untact tourism in Korean context) in the COVID-19 era, and The negative impacts on travel businesses and behaviours from COVID-19. Especially, the adverse effects of COVID-19 have made an enormous decline in rural experience tourism destinations and cancellation of local festivals. On the other hand, new tourism activities have emerged due to COVID-19. Those activities have included camping, drive-thru destinations, and cycling. Ecological and natural tourist sites such as Ungok Wetland, Seonunsan Mountain, Seonunsa Temple, and Gusipo Beach appeared. These tourist destinations have a quiet atmosphere and less density place noncontacting with other people when visiting. Also, because overseas travel has become difficult, long-term stay travel in rural areas has appeared. This study indicates that COVID-19 has less impacted rural tourism than other tourism destinations with these positive and negative impacts.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1399-1404
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• 2012

Because satellites operate in space, it is impossible to repair them when they malfunction. Therefore, to ensure the normal function of the payload used in the satellites, accurate assembly and installation of parts are crucial. To prevent abnormal functioning in the extreme environments during launch and in space, it is essential to test changes at the parts and system levels by performing alignment measurement before and after the launch environment test and the space environment test. Recently, noncontact three-dimensional precision machinery for medium- and large-sized parts has been developed. One of these is the theodolite measurement system, which is widely used in the aerospace industry. This study measures the angle of the dual thruster module that is used to control the attitude of KOMPSAT by using a theodolite, and alignment measurement and a reliability analysis are performed.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.3
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• pp.226-232
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• 2014

In the present study, the characteristics of laser ultrasound in the ablation regime are investigated using simulations and experiments. The laser ultrasonic technique has been recognized as a noncontact method in the field of nondestructive tests (NDTs). In hostile environments (such as hot temperatures), this method has various advantages over the conventional contact ultrasonic method. In particular, in the ablation regime, the laser ultrasonic technique is suitable for inspecting internal defects because of the high amplitude and directivity of the longitudinal wave. In this paper, a simulation model for laser ultrasound in the ablation regime was developed. This model was subsequently applied to a defective specimen using the B-scan method to locate defects. Finally, we performed an experimental test to verify the simulation results. Consequently, the simulation demonstrated good agreement with the experimental test.