• Journal of Ocean Engineering and Technology
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• v.36 no.1
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• pp.11-20
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• 2022

Generally, tsunamis are generated by the rapid crustal movements of the ocean floor. Other factors of tsunami generation include landslides on coastal and ocean floor slopes, glacier collapses, and meteorite collisions. In this study, two numerical analyses were conducted to examine the formation, propagation, and deformation properties of landslide tsunamis. First, LS-DYNA was adopted to simulate the formation and propagation processes of tsunamis generated by dropping rigid bodies. The generated tsunamis had smaller wave heights and wider waveforms during their propagation, and their waveforms and flow velocities resembled those of theoretical solitary waves after a certain distance. Second, after the formation of the landslide tsunami, a tsunami based on the solitary wave approximation theory was generated in a numerical wave tank (NWT) with a computational domain that considered the stability/steady phase. The comparison of two numerical analysis results over a certain distance indicated that the waveform and flow velocity were approximately equal, and the maximum wave pressures acting on the upright wall also exhibited similar distributions. Therefore, an effective numerical model such as LS-DYNA was necessary to analyze the formation and initial deformations of the landslide tsunami, while an NWT with the wave generation method based on the solitary wave approximation theory was sufficient above a certain distance.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.348-348
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• 2017

This experiment was conducted to investigate the aspect of tiller occurrence, growth and yield of sorghum according to planting density and sowing date. The subject of this experiment is to supply basic data to inhibit non-productive tillers uneconomical and cumbersome for mechanical harvesting. Also another subject was to evaluate optimum planting density and sowing date in central district area. Total number of tillers was more in 80cm ridge than 60cm ridge and it was increased as the planting distance was wider from 15cm to 30cm on the each ridge. Ratio of effective tillers was higher in 60cm ridge than 80cm ridge and it was decreased as planting distance was wider from 15cm to 30cm. The lower the planting density, the more increased total number of tillers, whereas effective tillers were decreased as planting density was high. Average of total number of tillers of three varieties was higher in sowing date of 2 May (1st sowing date), whereas ratio of effective tillers was the highest in sowing date of 23 May (2nd sowing date). Hwanggeumchal showed the highest total number of tillers (1.2 tillers), while Moktaksusu had the lowest total number of tillers (0.8 tillers) among three varieties. There were no significant difference between planting density and days to heading and ripening date from seeding. Culm length increased as planting density was high, but ear length, grains per ear and 1000 grain weight were decreased on the other hand. The highest yield of sorghum per 10a was obtained from $60{\times}20cm$ planting density among 6 planting densities.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.7 no.2
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• pp.5-22
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• 2001

The purpose of this study was to investigate the balancing training effect on weight bearing ratio and postural sway on the unstable surface for the CVA patients with balance disability. The inclusion criteria were walking independently 20m distances. Eighteen subjects, 4 with right and 14 with left hemiplegic patients were participated in this study. The range of age was from 35 to 75 and the duration from onset time was from 1 to 38 months. The intervention program including balancing training that they were introduced for 10 minutes every other day during 12 weeks to experimental group, and general therapeutic exercise to control group. The result of this study were as following; 1. The balancing training on the unstable surface showed that the postural sway of left/right distribution would appear more effective on sitting with eyes opened. 2. The balancing training on the unstable surface showed that the postural sway of forward/rear distribution, left/right distribution and distance would appear more effective on standing with eyes opened. 3. The balancing training on unstable surface would increase more effective on the weight-bearing ratio of left/right difference and frequency. 4. The balancing training on unstable surface was statistical significant on the postural sway of left/right distribution and area in experimental group. and it was statistical significant on the postural sway of forward/rear distribution, left/right distribution and distance in control group, too.

• Journal of radiological science and technology
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• v.46 no.6
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• pp.509-517
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• 2023

This study analyzed imaging conditions and exposure index through clinical information collection and dose calculation programs in coronary angiography examinations. Through this, we aim to analyze the effective dose according to examination conditions and provide basic data for dose optimization. In this study, ALARA(As Low As Reasonably Achievable)-F(Fluoroscopy), a program for evaluating the radiation dose of patients and the collected clinical data, was used. First, analysis of imaging conditions and exposure index was performed based on the data of the dose report generated after coronary angiography. Second, after evaluating organ dose according to 9 imaging directions during coronary angiography, with the LAO fixed at 30°, dose evaluation was performed according to tube voltage, tube current, number of frames, focus-skin distance, and field size. Third, the effective dose for each organ was calculated according to the tissue weighting factors presented in ICRP(International Commission on Radiological Protection) recommendations. As a result, the average sum of air kerma during coronary angiography was evaluated as 234.0±112.1 mGy, the dose-area product was 25.9±13.0 Gy·cm², and the total fluoroscopy time was 2.5±2.0 min. Also, the organ dose tended to increase as the tube voltage, milliampere-second, number of frames, and irradiation range increased, whereas the organ dose decreased as the FSD increased. Therefore, medical radiation exposure to patients can be reduced by selecting the optimal tube voltage and field size during coronary angiography, maximizing the focal-skin distance, using the lowest tube current possible, and reducing the number of frames.

• Journal of the Korean Institute of Navigation
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• v.2 no.1
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• pp.15-34
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• 1978

This paper deals with the study of the effective reflecting area of the land targets for the improvement of the map of the Radar Simulator, through the analysis of the pictures on P.P.I Scope. It is very important to anticipate the effective refiecting area of land marks, either forinterpretation of radar scope or for simulating accurately the radar scope, but has seldom been studied theoretically or experimentarily, especially on the stand point of simulating the radar scope. Most of the maps of Radar Simulator in use are made without consideration of the effective reflecting area of land marks, so that the P.P.I. Scope of the Radar Simulator may show much different pictures from the actual shore line and other targets. This paper has derived the following conclusiions by experimental procedures. 1. The effective area of the land target greatly varies according to the gradient of the contours, roughness and material of the land surfaces, so that simulator maps of uniformly coated land taret practically used now many be effectively improved by varying the intensity of the land marks proposed in this paper. 2. The intensity of the land targets on the P.P.I. is also related much to the distance from the radar, so that the precalculation of this effect may results in a much simulated P.P.I. picture improved. 3. If the ambient condition is constant, the intensity of the picture increases as the height of the targets is increased.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.83-87
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• 2008

Purpose: This study was investigated for the effects of vision training on the phoria and positive fusion reverse (PFR) of patients with convergence insufficiency (C.I). Methods: Subjects were included 11 patients with CI of T Vision Center (5 patients with distance orthophoria, 6 patients with distance exophoria). The vision training of this study had been processed daily during an average of 2 months for each patients. Results: The result showed that after vision training, the phoria and PFR of CI patient were improved significantly than that before vision training (p<0.05) and when the groups were divided to the distance orthophoria convergence insufficiency (DOCI) group and distance exophoria convergence insufficiency (DE-CI) group, these improvements were proved similarly in the both groups. Conclusions: This study proved that vision training for patients with C.I was effective for the improvement of the phoria and PFR of these patients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.4
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• pp.229-239
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• 2009

The purpose of this study is to evaluate the change in condylar position, width, and angle before and after orthognathic surgery using 3-dimensional computed tomograph. Pre and posterative 3-D CT was taken on 38 patients and through axial, frontal, sagittal measurements and by 3-dimensional reconstruction, the changes in condylar postion, mandibular width and angle were analyzed and others such as the difference in gender, operation and fixation method, setback length and in relation with temporomandibular disorders were done together too. The results were as follows: The inward rotation of condyle in axial condylar angle, the forward movement of right condyle in sagittal anterior-posterior distance, the superior movement of both condyles in sagittal superior-inferior distance, the decrease in gonial angle, the increase in mandibular width, the decrease in distance between the axial coronoid process distance and the increase in the frontal intercondylar distance were statistically significant. There were no statistically significant changes in gender difference, however in the difference in operation method, change in the gonial angle was observed and there was more change in bilateral sagittal split osteotomy group compared to two-jaw surgery group. In the difference in fixation method, the decrease in axial coronoid process distance and the change in sagittal anterior-posterior distance were statistically significant. In the difference in setback, the increase in setback didn't relate directly with the increased change in condyle position. In the relation with temporomandibular disorder, changes in left axial condylar angle and axial coronoid process distance were statistically significant. Changes in condylar position could be observed after the orthognathic surgery but it doesn't seem to have much of a clinical importance. The orthognathic surgery is effective in decreasing the mandibular angle, and it is not related with the temporomandibular disorder.

• Korean Security Journal
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• no.15
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• pp.303-316
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• 2008

One of important protecting skill is securing the minimum safe distance from potential hazard to protect protectee in the emergency situation, that is basic thing for the detailed security in relation to the walking formation and the distance between protectee and crowed. This thesis is to provide the idea on the scientific countermeasure in the gun attack situation, by presenting logic on the reaction time and it's moving distance, on the safe distance between protectee and crowed. Handball goal keeper's reaction time of 0.33seconds is applied, because handball goal keeper's reaction style is very similar to security agent's reaction style. And 4m/sec of record is applied, that is average speed of 'go and return type run of 40m' to calculate it's moving distance. Several researches show that reaction time could be improved by continuing training, similarly security agents could improve their reaction time, providing better reaction skill. The important thing is that it make big difference in the protecting result, although the shortening of reaction time is too slight. Securing safe distance between protectee and crowed and the distance between protectee and security agent could provide effective reaction environment with 'natural protective wall effect' by security agent

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.165-170
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• 2009

Pressure ripple, vibration and noise level are measured in each parts of the power steering system. MD(Mahalanobis Distance) is calculated by using MTS(Mahalanobis Taguchi System) with measured data, and noise sensitive components are selected. The components applied detail design parameters are made and data is measured. After that MD is calculated also. Mean value and SN ratio can be obtained from the MD. Effective noise reduction technique and dominant design parameters in hydraulic power steering system are introduced.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.272-278
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• 1999

It is the effective method to diagnosis damage process of gear system such as automobile transmission to observe wear particle in gear oil. We tested with new transmission and took out gear oil according to drive distance. 4 shape parameters of wear particles in gear oil were calculated and wear volume were presumed with the image processing system. To be applied to damage diagnosis of gear system in transmission of automobile, we discuss number of wear particles, shape characteristics and total wear volume according to driving distance.