• Phonetics and Speech Sciences
• /
• v.7 no.1
• /
• pp.151-163
• /
• 2015

In this study, we aim to describe kinematic characteristics of Korean /l/-flapping in two speech rates (fast vs. comfortable). Production data was collected from seven native speakers of Seoul Korean (four females and three males) using electromagnetic midsagittal articulometry (EMMA), which provided two dimensional data on the x-y plane. We examined kinematic properties of the vertical/horizontal tongue tip gesture, the vertical/horizontal (rear) tongue body gesture, and the jaw gesture in an /i/-/i/ context. Gestural landmarks of the vertical tongue tip gesture are directly measured. This serves as the actual anchoring time points to which relevant measures of other trajectories referred. The study focuses on velocity profiles, closing/opening spatiotemporal properties, constriction duration, and constriction minima were analyzed. The results are summarized as follows. First, gradiently distributed spatiotemporal values of the vertical tongue tip gesture were on a continuum. This shows more of a reduction in fast speech rate, but no single instance of categorical reduction (deletion). Second, Korean /l/-flapping predominantly exhibited a backward sliding tongue tip movement, in 83% of production, which is apparently distinguished from forward sliding movement in English. Lastly, there was an indication of vocalic reduction in fast rate, truncating spatial displacement of the jaw and the tongue body, although we did not observe positional variations with speech rate. The present study shows that Korean /l/-flapping is characterized by mixed articulatory properties with respect to flapping sounds of other languages such as English and Xiangxiang Chinese. Korean /l/ flapping demonstrates a language-universal property, such as the gradient nature of its flapping sounds that is compatible with other languages. On the other hand, Korean /l/-flapping also shows a language-particular property, particularly distinguished from English, in that a backward gliding movement occurs during the tongue tip closing movement. Although, there was no vocalic reduction in V2 observed in terms of jaw and tongue body height, spatial displacement of these articulators still suggests truncation in fast speech rate.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.639-644
• /
• 2011

The purpose of this study was to provide quantified data on the throwing skills of world-class athletes and to analyze the kinematic variables for women shot-putters at the IAAF World Championships Daegu 2011. Three-dimensional motion analyses of the eight players who qualified for the final round were carried out to obtain the data. The Kwon3D XP program was used for image analysis of the kinematic data, which included the configurations of each joint. The following conclusions were arrived at. The throwing distance increased with an increase in the release speed, and a significant correlation (p <. 01) was observed between the throwing distance and release speed. It was also shown that players using the spin technique increased their release speed with a fast shoulder-rotation-angle speed. The release height varied with their height and showed a significant difference with the record. This showed that the release angle did not greatly influence the record for the game, but varied with their technical and physical characteristics. Therefore, an increase in release speed is required to improve the record.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.529-540
• /
• 2011

The purpose of this study was to evaluate the kinematic characteristics of $5^{th}$ and $6^{th}$ hurdle clearances during the final of the 110-m hurdles at the IAAF World Championships, Daegu 2011. To this end, the hurdling motions of the top 4 ranked male hurdlers in the competition were analyzed. A total of 12 cameras were used to record their motions, with a sampling frequency of 120 Hz. The cameras were calibrated using $11{\times}2{\times}1\;m$ control objects that covered all of the lanes (1st~8th lanes). After analyzing all the data, we arrived at the following results. In the take-off phase, all athletes revealed similar take-off times (CT), and similar distances from the take-off to hurdleto (L1) and hurdle to landing (L2). In particular, Turner, ranked $3^{rd}$, had an inconsistent L2 and may need further training to correct it. In the flight phase, Richardson, ranked $1^{st}$, showed the longest flight distance, whereas Xiang, who was ranked $2^{nd}$, showed the highest CG height from the hurdle. For the step patterns, to increase the pitch frequency, Richardson and Xiang used shorter 3-step lengths than Turner and Oliver.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.4
• /
• pp.117-129
• /
• 2005

The purpose of this study was to characterize the impact shock wave and its attenuation, and the kinematic response of the lower extremity's joints to the impact shock during downhill running in which the lower extremity's extensor acts dominantly. For this study, fifteen subjects(mean age:$27.08{\pm}4.39$; mass:$76.30{\pm}6.60$; height:$177.25{\pm}4.11$) were required to run on the 0% grade treadmill and downhill grades of 7%, and 15% in random at speed of their preference. When the participant run, acceleration at the tibia and the sacrum and kinematic data of the lower extremity were collected for 20s so as to provide at least 5 strides for analysis at each grade. Peak impact accelerations were used to calculate shock attenuation between the tibia and sacrum in time domain at each grade. Fast Fourier transformation(FFT) and power spectral density(PSD) techniques were used to analyze impact shock factors and its attenuation in the frequency domain. Joint coordinate system technique was used to compute angular displacement of the ankle and knee joint in three dimension. The conclusions were drawn as fellows: 1. Peak impact accelerations of the tibia and sacrum in downhill run were greater than that of 0% grade run, but no significant between conditions. Peak shock of PSD resembled also in pattern of peak impact acceleration. The wave of impact shock attenuation between the tibia and sacrum decreased with increasing grade, but didn't find a significant difference between grade conditions. 2. Adduction/abduction, flexion/extention, and internal/external rotation of the ankle and knee joints at support phase between grade conditions didn't make much difference. 3. At grade of 7% and 15%, there were relationship between the knee of the flexion/extension movement and peak impact acceleration during heel strike and found also it in the ankle of plantar/dorsiflexion at grade of 15%.

• Korean Journal of Applied Biomechanics
• /
• v.29 no.1
• /
• pp.23-32
• /
• 2019

Objective: The aim of this study was to provide kinematic data on the characteristics of spinal disease patients by comparing and analyzing kinematic variables related to foot balance and gait pattern of spinal disease. Method: The subjects of the study included 40 adult men and 60 adult women who visited the hospital in Busan. Patients who were diagnosed with spinal disease by a physician through X-ray examination were selected as subjects for the diagnosis of vertebral disc herniation, spinal stenosis, spinal disease diagnosed with spinal disease and the general public. Left and right foot pressure and contact area were checked by Gaitview pro meter. X-ray photographs were taken with a Zen-2090 mobile fluoroscopy under physicians' direct participation. One-way ANOVA was performed to compare the differences between the kinematic variables and post-hoc was performed by the Duncan method. Results: The difference in contact area between the left foot and the right foot was $115.30{\pm}14.15cm^2$ in the left side and $124.25{\pm}13.65cm^2$ in the left side in the spinal disease patients. The difference in pressure between the left and right side of the spinal disease patients was wider than that of the general people. Especially, the right side of the spinal disease patients showed a larger area of left foot contact than the general population. Conclusion: Spinal disease patients have wider contact area of the left foot than those of the general population. In the case of right spinal disease, the left foot support area is widened due to pain. In the gait, women showed slightly more posterior body center than men, and the upper body muscle imbalance and immobilization due to the spinal disease caused imbalance of the muscles moving to the lower limb, It was analyzed to inhibit movement.

• Journal of the Korean Society of Industry Convergence
• /
• v.21 no.5
• /
• pp.197-205
• /
• 2018

In this research, tricycle vehicle simulation based on multi-body environment has been introduced. Mathematical model of tricycle vehicle was developed. In this research the left and right wheel speed are calculated based on the rear steering angle and velocity. The kinematic model for the three - wheel drive system was completed and the results were analyzed using the actual vehicle drawings. Through simulink vehicle performance on linear and rotation movement were simulated. Using the mathematical model the control system can be applied directly to the tricycle vehicle. The simulation result shows that the proposed vehicle model is successfully represent the movement characteristics of the real vehicle. This model assists the vehicle developer to create the controller and understand the vehicle during the development process.

• Tribology and Lubricants
• /
• v.25 no.6
• /
• pp.432-437
• /
• 2009

The effect of oxidation in SAE 5W30 engine oils on friction and wear characteristics was investigated using reciprocating bench tester and shell 4-ball tester. Commercial engine oils were collected and oxidized using the KS M 2021 method modifying the oxidation time. Kinematic viscosity, total acid number(TAN), FT-IR spectrum and total base number(TBN) also measured to examine the chemical change of oils with oxidation. The results showed that TAN was slightly changed and Kinematic viscosity was suddenly increased during the oxidation stage. however, TBN results keep a constant slope after TBN linearly decreased with oxidation time. Spectroscopy results showed that spectrums were orderly increased at $1710cm^{-1}$ during the oxidation time. Friction test results showed that oxidation of oils formed unstable friction layers causing higher fluctuating friction. however, the wear resistance was independent of oxidized time due to the different friction characteristics by oxidation. We found several factors in relation to lubrication properties with oxidation time. This factors were Viscosity, TBN, change of FT-IR spectrum, friction coefficient using reciprocating bench tester and wear scar.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.1 no.3
• /
• pp.1-10
• /
• 1997

It is recognized that the dynamic of a structure is affected by the characteristics of the soil layer and foundation. However the design codes for the seismic design of structures are partially reflecting the caharcteristics of the soil layers due to the inherent complexity of them and the lack of systematic study results for the foundation-soil system, and leading to unconservative or too conservative results. In this study, the kinematic interaction effects of foundation-soil system was investigated for the seismic analyses of structures estimating the effects of the shear wave velocity, the depth of the soil layer, the embedment of a foundation and pile foundation, and the modified classification criteria of soil layers are proposed for the reasonable seismic analyses of structures considering the characteristics of soil layers and foundations. For the embedded medium or large foundations (including pile foundations), at least 60m soil layer below the foundation should be considered for the seismic analyses of structures to tate into account the kinematic interaction effects of the foundation-soil system, and also the rocking motion of foundation-soil system with or without piles should be included in the seismic analyses of structures.

• PNF and Movement
• /
• v.20 no.2
• /
• pp.295-306
• /
• 2022

Purpose: This study aimed to investigate the effect of robot-assisted gait training on the active ranges of motion, gait abilities, and biomechanical characteristics of gait in patients who underwent lower extremity surgery, and to verify the effectiveness and clinical usefulness of robot-assisted gait training. Methods: This study was conducted on 14 subjects who underwent lower extremity surgery. The subjects participated in robot-assisted gait training for 2 weeks. The active ranges of motion of the lower extremities were evaluated, and gait abilities were assessed using 10-m and 2-min walk tests. An STT Systems Inertial Measurement Unit was used to collect data on biomechanical characteristics during gait. Spatiotemporal parameters were used to measure cadence, step length, and velocity, and kinematic parameters were used to measure hip and knee joint movement during gait. Results: Significant improvements in the active ranges of motion of the hip and knee joints (flexion, extension, abduction, and adduction) and in the 10-m and 2-min walk test results were observed after robot-assisted gait training (p < 0.05). In addition, biomechanical characteristics of gait, spatiotemporal factors (cadence, step length, and velocity), and kinematic factors (gait hip flexion-extension, internal rotation-external rotation angle, and knee joint flexion-extension) were also significantly improved (p < 0.05). Conclusion: The results of this study are of clinical importance as they demonstrate that robot-assisted gait training can be used as an effective intervention method for patients who have undergone lower extremity surgery. Furthermore, the findings of this study are clinically meaningful as they expand the scope of robot-assisted gait training, which is currently mainly applied to patients with central nervous system conditions.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.2
• /
• pp.125-139
• /
• 2008

The purpose of this study is to compare and analyze a kinematic characteristics of throwing performance among born visually impaired, postnatal visually impaired and visually correct people through their kinematic characteristics. Another purpose of this study is to prevent injury and improve blind's exercise leadership and physical abilities. Three video cameras were used and each camera's shooting velocity was 60field/sec. Then the longest thrown pose was collected and analyzed by using Kwon 3D ver. 3.1 program. The results obtained from this study were followings; 1. During release, the fastest speed of ball was visually corrected followed by postnatal visually impaired and then born visually impaired. 2. Visually corrected used wrist joint well and had wide body round range with similar motion patterns, however born visually impaired couldn't do this at all. 3. Visually corrected used waist to lead shoulder at Phase 2 while throwing ball, but some of born visually impaired and postnatal visually impaired couldn't use waist to lead shoulder. 4. Visually corrected looked at the way where ball would go, but blinds couldn't look where ball would go. 5. Not like visually corrected who show similar patterns, born visually impaired showed each different patterns and some postnatal visually impaired showed similar patterns with visually corrected. 6. While throwing ball, visually corrected showed flexible weight-movement, postnatal visually impaired were not good as visually corrected, and born visually impaired couldn't do weight-movement at all. Synthetically, this result showed that throwing motions are affected a lot by the time when people became blind.