• Proceedings of the KSME Conference
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• 2003.04a
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• pp.537-543
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• 2003

This paper presents the improved procedure to assess static and dynamic strength of crawler type excavators. A fully integrated model including front attachment and chassis was prepared for structural analysis. In this paper, two types of loading input methods were investigated and the method imposing digging force directly on bucket tooth was more convenient than imposing cylinder reaction force on cylinder pin even if the two methods showed no discrepancy in analysis results. Static strength analysis was carried out for eight analysis scenarios based on two extreme digging positions, maximum digging reach position and maximum digging force positions. The results from static strength analysis were compared with measured stresses, cylinder pressures and digging forces and showed a good quantitative agreement with measured data. Dynamic strength analysis was carried out for simple reciprocation of boom cylinders. It was recognized that the effect of compressive stiffness of hydraulic oil was very important for dynamic structural behavior. The results from dynamic strength analysis including hydraulic oil stiffness were also compared with measured acceleration data and showed a qualitative agreement with measured data.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.533-538
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• 2009

The magnitude of constraint effect $A_2$ values on the non-linear elastic plastic fracture toughness was experimentally estimated by using displacement at various measuring positions near crack tip. Constraint effect $A_2$ value was dependent on specimen configuration and on the measured displacement near crack front. The crack tip opening displacement in the vicinity of the crack tip front should be estimated within plastic region when appropriately constraint effect was calculated. It was found that the magnitude of constrain effect |$A_2$| is below 8.0 at the crack tip. But an appropriate location to measure the effective constraint effects $A_2$ at the critical value of J that crack initiation is characterizable by is r = 2mm and ${\theta}=90^{\circ}$ away from original crack tip, and the constraint effect |$A_2$| estimated is 5.3.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.214-215
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• 2002

Generally uniform dose distribution is assumed to be formed in a target region when a conventional dose formation method using a broad proton beam, a fixed modulation technique, a bolus and an aperture is employed. However, actual situations differ. We usually find non-uniformity in the target region. This is due to the insertion of a range-compensating bolus before the patient. Since the range-compensating bolus has an irregular shape, the scattering in the bolus depends on the lateral position. Dose distribution is overlapping results of dose distribution of pencil-proton beams traversing different lateral positions of the bolus. The lateral extent of dose distribution of each pencil beam traversing the different position differs each other at the same depth in the target object. This is a cause of the non-uniformity of the dose distribution. Therefore the same lateral extent of dose distribution should be attained for different pencil beams at the same depth to obtain a uniform dose distribution. For that purpose, we propose here a bi-material bolus. The bi-material bolus consists of a low-Z material determining mainly the range loss and a high-Z material defining mainly the scattering in the bolus. After passing through the bi-material bolus, protons traversing different lateral positions will have different residual range yet with the same lateral spread at a certain depth. Using the optimized bi-material bolus, we can obtain a more uniform dose distribution in the target region as expected.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.4
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• pp.14-23
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• 2008

Information Technology (IT) managers play an important role as a bridge between technology and business, and it is therefore important to determine what skills are required for this position. Although many previous studies have investigated the skills necessary for IT managers to perform their roles, most of these studies are based on the data collected from companies in the US. However, given the increased labor mobility in the IT industry, it is important to determine whether IT manager positions elsewhere require the same skills as the positions in the US. This study is a first step in this direction and attempts to determine whether there are any differences in skill requirements between Korean IT managers and American IT managers, and, if so, what they are.

• The Journal of the Acoustical Society of Korea
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• v.13 no.5
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• pp.69-76
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• 1994

Acoustic cues of some consonantal phonology were tested in Korean words. All Korean consonants were recorded and acoustically analyzed in controlled phonological environments :ⅰ) word-initial, ⅱ) inter-vocalic, and ⅲ) word-final positions. The observed acoustic regulations are : ⅰ) The lengths of obstruents are longer word-initially than word-finally, ⅱ) The lengths of sonorants are longer word-finally than in word-initial or inter-vocalic positions, ⅲ) The formants of the lateral sound /l/ are higher word-finally than intervocalically. The phonological explanations of these acoustic regulations can be found in the rules of ⅰ) inter-vocalic voicing of plain stops, ⅱ) syllable-final unreleasing of obstruents, ⅲ) word-initial aspiration of stops, and ⅳ) liquid alternation between [r] and [l]. Numerical data of all these acoustic regulations are reported in order to facilitate their application toward improving naturalness for speech synthesis and accurateness for speech recognition.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.202-208
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• 2020

Body balance necessary for ordinary daily activities can be undermined by diverse causes. In this study, as a way to control such a problem, we have produced smart insole as a wearable device in the form of insole and developed analysis software evaluating body balance, which measures ground reaction force applied to each area of sole and Center of Pressure (COP). The software visualized changes in COP positions while a user was moving and average COP positions, and it is also capable of measuring the COP values in the Anterior-Posterior (AP) and Medial-Lateral (ML) areas of feet. Through gait analysis, it can analyze the time of walking, strides, speed, COP trajectory while walking, etc. In addition, we have developed training contents for body balance improvement designed in consideration of Y-Balance Test and Timed Up and Go (TUG) Test. They were established in virtual reality similar to daily living environment so that people can expect more effective training results regardless of places.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.1
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• pp.94-100
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• 2014

In order to intercept anti-ship missiles, it is important to accurately predict the aiming point. The major factor for degrading the accuracy of the aiming point is the motions of the warships due to waves. Therefore, a stage of correcting the aiming point is required to compensate for such motions of warships. The proposed aiming point correction technique treats the changes in positions and velocity of naval guns by considering changes in the positions and velocities of the anti-ship missiles. In this paper, a ship motion estimation filter was also constructed to predict the motions of warships at the firing time of naval guns. In the simulation part, finally, the distance errors before and after aiming point corrections were compared through 6-DOF simulations.

• The Journal of Korean Physical Therapy
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• v.25 no.4
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• pp.217-223
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• 2013

Purpose: This study was to investigate whether the two different head postures, natural and ideal head posture, affect head/shoulder posture and muscle activity. Methods: Thirty healthy subjects with the forward head and round shoulder posture were participated in this study. This study utilized a within-subjects design with subjects being positioned into two sitting positions: natural head posture (NHP) and ideal head posture (IHP). Forward head angle (FHA) and forward shoulder angle (FSA) of each subject were measured for assessing the head/shoulder posture and muscle activities of upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) during the forward overhead reaching. Results: There were significant increases in both FHA and FSA after taking IHP, which showed greater angles than in taking NHP. In change of muscle activities, there were significant decreases in both LT and SA after taking IHP, which showed lower activities than in taking a NHP, whereas there was no significant change in UT. Conclusion: These findings demonstrate that postural alterations associated with forward head and rounded shoulder postures could alter scapular kinetics and muscle activity during the forward overhead reaching.

• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.281-292
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• 2016

In this research, 10 specimens of FCAW welding with positions of 1G and 3G were tested to confirm the weldability, welding positions, and welded joint performance of 60mm HSA800 steel. The test results showed that FCAW 1G and 3G satisfied HSA800 steel's KS and the criteria for homogeneity of strength, indicating a good weld zones. However, according to the tensile test results of weld zone, 3G position FCAW welding requires improvement of welding techniques and methods.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.10
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• pp.963-968
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• 2010

This paper handles ZMP based control that is inspired by neural networks for humanoid robot walking on varying sloped surfaces. Humanoid robots are currently one of the most exciting research topics in the field of robotics, and maintaining stability while they are standing, walking or moving is a key concern. To ensure a steady and smooth walking gait of such robots, a feedforward type of neural network architecture, trained by the back propagation algorithm is employed. The inputs and outputs of the neural network architecture are the ZMPx and ZMPy errors of the robot, and the x, y positions of the robot, respectively. The neural network developed allows the controller to generate the desired balance of the robot positions, resulting in a steady gait for the robot as it moves around on a flat floor, and when it is descending slope. In this paper, experiments of humanoid robot walking are carried out, in which the actual position data from a prototype robot are measured in real time situations, and fed into a neural network inspired controller designed for stable bipedal walking.