• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.2
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• pp.349-353
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• 2016

The purpose of this study was to investigate possible age differences in the attenuation of acceleration in the upper body (from pelvis through shoulder to head) during fast walking. Thirty young and 29 elderly subjects participated in this study. Wireless acceleration sensors were attached on head, shoulder, and pelvis. Subjects performed two trials of fast walking on a treadmill, where the fast speed was defined as 1.5 times of the comfortable speed. Root-mean-squared (RMS) accelerations of each axis were compared with age group and sensor position as independent factors. In the AP direction, the pelvis acceleration was greater in the young and the shoulder-to-head attenuation was also greater in the young (p<0.001), so that the head acceleration was comparable between age groups (p=0.581). In the ML direction, the pelvis acceleration was greater in the young and also the pelvis-to-shoulder attenuation was greater in the young (p<0.001), so that the head acceleration was greater in the elderly group (p<0.001). Insufficient attenuation ML acceleration in the elderly resulting in the greater acceleration in the head may deteriorate the balance control which utilize feedback signals from the sensory organs in head, e.g., vestibular and visual systems.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.273-284
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• 2016

Objective: The purpose of this study was to investigate effects of upper limb, trunk, and pelvis kinematic variables on the velocity of Apkubi Momtong Baro Jireugi in Taekwondo. Method: Twenty Taekwondo Poomsae athletes (age: $20.8{\pm}2.2years$, height: $171.5{\pm}7.0cm$, body weight: $66.2{\pm}8.0kg$) participated in this study. The variables were upper limb velocity and acceleration; trunk angle, angular velocity, and angular acceleration; pelvis angle, angular velocity, and angular acceleration; and waist angle, angular velocity, and angular acceleration. Pearson's correlation coefficient was calculated for Jireugi velocity and kinematic variables; multiple regression analysis was performed to investigate influence on Jireugi velocity. Results: Angular trunk acceleration and linear upper arm punching acceleration had significant effects on Jireugi velocity (p<.05). Conclusion: We affirmed that angular trunk acceleration and linear upper arm punching acceleration increase the Jireugi velocity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.840-844
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• 2013

In this study, we try to estimate vascular compliance for management vascular disease. Because It is known the vascular compliance represents the state of the blood vessels. In general, the vascular compliance is estimated using an acceleration photoplethymogram from measured by photoplethymogram-based. The acceleration photoplethymogram is come from second derivative of photoplethymogram. By using the acceleration photoplethymogram, we can estimating vascular compliance, vascular age, vascular state. In this study, for measuring acceleration photoplethymogram we have developed a measurement device having analog filters. It has the advantage of miniaturization, low-power because it is simpler than digital filters. Using the developed device, we have estimated vascular compliance and tested the reliability of our device compare with conventional device having digital filters. As a result.

• Journal of Life Science
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• v.33 no.9
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• pp.730-735
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• 2023

In the past decade, numerous studies have been carried out to quantify aging with the help of artificial intelligence. Using DNA methylation data, various models have been developed; these are commonly called epigenetic clocks. Epigenetic age acceleration is usually associated with disease conditions. Schizophrenia is a mental illness associated with severe mental and physical stress. This disease leads to high mortality and morbidity rates in young people compared with other psychological disorders. In the past, the research community considered this disease to be related to the accelerated aging hypothesis. In the current study, we wanted to investigate the epigenetic age acceleration changes in schizophrenia patients to obtain epigenetic insights into the disease. To measure the epigenetic age acceleration, we used two different DNA methylation clock models, namely, Horvath clock and Epi clock, as these are pan-tissue models. We utilized 450k array data compatible with both clocks. We found a slower epigenetic acceleration in the patients' samples when we used the Epi clock. We further analyzed the differentially methylated CpG sites between the control and cases and performed pathway enrichment analysis. We found that most of the CpGs are involved in neuronal processes.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.177-183
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• 2023

The purpose of this study was to examine the effects of 8 weeks of resistance exercise on gait-related abilities and the differences in age groups to provide reference materials for application of training by age group. Subjects in their 30s, 40s, and 50s were recruited and subjected to a lower extremity exercise, in which the intensity gradually increased three times a week for eight weeks. The gait-related variables, torque at 0.18 sec, acceleration time, and torque at 30°, were assessed through isokinetic tests before and after the 8-week training. The torque at 0.18 sec showed a significant increase in the 50s group. There was no significant difference in acceleration time according to time and group. The torque at 30° showed a significant increase in the 30s group. In conclusion, 8 weeks resistance training can increase neuromuscular activity in adults in their 50s group, and changes in training variables are needed to increase torque at 30° that affects knee stabilization in adults over 40s group.

• Korean Journal of Applied Biomechanics
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• v.30 no.2
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• pp.145-154
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• 2020

Objective: The purpose of this study was to determine the relationship between impact and shear peak force, and tibia-accelerometer variables during running. Method: Twenty-five male heel strike runners (mean age: 23.5±3.6 yrs, mean height: 176.3±3.3 m/s, mean mass: 71.8±9.7 kg) were recruited in this study. The peak impact and anteroposterior shear forces during treadmill running (Bertec, USA) were collected, and impact shock variables were computed by using a triaxial accelerometer (Noraxon, USA). One-way ANOVA was used to test the influence of the running speed on the parameters. Pearson's partial correlation was used to investigate the relationship between the peak impact and shear force, and accelerometer variables. Results: The running speed affected the peak impact and posterior shear force, time, slope, and peak vertical and resultant tibial acceleration, slope at heel contact. Significant correlations were noticed between the peak impact force and peak vertical and resultant tibia acceleration, and between peak impact average slope and peak vertical and resultant tibia acceleration average slope, and between posterior peak (FyP) and peak vertical tibia acceleration, and between posterior peak instantaneous slop and peak vertical tibial acceleration during running at 3 m/s. However, it was observed that correlations between peak impact average slope and peak vertical tibia acceleration average slope, between posterior peak time and peak vertical and resultant tibia acceleration time, between posterior peak instantaneous slope and peak vertical tibial acceleration instantaneous slope during running at 4 m/s. Conclusion: Careful analysis is required when investigating the linear relationship between the impact and shear force, and tibia accelerometer components during relatively fast running speed.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.332-337
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• 2005

In order to investigate performance changes, the acceleration, vibration, and braking performance tests were carried out on the electric multiple units (EMUs) with over 20 years operation. According to the testing results, in vibration and braking performance, the similar performance results were obtained as compared with newly manufactured EMUs. However, in terms of acceleration performance, below reference value (3.0 km/h/s) has been obtained. This is mainly due to performance deterioration including traction motor. The precision diagnosis evaluation of deteriorated EMUs will be provided through the overall evaluation of corrosion testing and structural performance of car body.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.741-744
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• 2003

In this study, the influence of chemical admixture on early strength development of concrete is discussed. According to the results, fluidity with variation of kinds of chemical admixture is lower in the case of acceleration type than in the case of normal type. Setting time of naphthalene acceleration type is shortened by I hour, and that of melamine is nearly same, but that of polycarbonic acid is somewhat retarded in comparison with that of naphthalene normal type. Early compressive strength gains 5MPa in about 18hours regardless of the kinds of chemical admixture. But as time elapses, compressive strength is higher in order of polycarbonic acid, naphthalene and melamine type. The relativity between compressive strength and the rebound value of P-type schmidt hammer is also favorable at early age, and compressive strength of 5MPa is estimated at the rebound value of 22.

• Korean Journal of Applied Biomechanics
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• v.34 no.2
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• pp.81-92
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• 2024

Objective: The purpose of this study was to analyze the impact acceleration, shock attenuation and biomechanical variables at various running speed. Method: 20 subjects (height: 176.15 ± 0.63 cm, weight: 70.95 ± 9.77 kg, age: 27.00 ± 4.65 yrs.) participated in this study. The subjects ran at four different speeds (2.5 m/s, 3.0 m/s, 3.5 m/s, 4.0 m/s). Three-dimensional accelerometers were attached to the distal tibia, sternum and head. Gait parameters, biomechanical variables (lower extremity joint angle, moment, power and ground reaction force) and acceleration variables (impact acceleration, shock attenuation) were calculated during the stance phase of the running. Repeated measures ANOVA was used with an alpha level of .05. Results: In gait parameters, decreased stance time, increasing stride length and stride frequency with increasing running speed. And at swing time 2.5 m/s and 4.0 m/s was decreased compared to 3.0 m/s and 3.5 m/s. Biomechanical variables statistically increased with increasing running speed except knee joint ROM, maximum ankle dorsiflexion moment, and maximum hip flexion moment. In acceleration variables as the running speed increased (2.5 m/s to 4.0 m/s), the impact acceleration on the distal tibia increased by more than twice, while the sternum and head increased by approximately 1.1 and 1.2 times, respectively. And shock attenuation (tibia to head) increased as the running speed increased. Conclusion: When running speed increases, the magnitude and increasing rate of sternum and head acceleration are lower compared to the proximal tibia, while shock attenuation increases. This suggests that limiting trunk movement and increasing lower limb movement effectively reduce impact from increased shock. However, to fully understand the body's mechanism for reducing shock, further studies are needed with accelerometers attached to more segments to examine their relationship with kinematic variables.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.16-23
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• 2021

Objective: The purpose of the study was to compare the acceleration and shock attenuation (SA) of the runners with/without low back pain (LBG vs. NLBG) while running at 2.5 m/s, 3.0 m/s, 3.5 m/s and 4.0 m/s. Method: 15 adults without low back pain (age: 23.13±3.46 years, body weight: 70.13±8.94 kg, height: 176.79±3.68 cm, NLBG) and 7 adults with low back pain (age: 27.14±5.81 years, body weight: 73.10±10.74 kg, height: 176.41±3.13 cm, LBG) participated in this study. LBG was recruited through the VAS pain rating scale. All participants ran on an instrumented treadmill (Bertec, USA). Results: The LBG shows statistically greater vertical acceleration at the distal tibia during running at 3.5 m/s and 4.0 m/s and greater shock attenuation from the distal tibia to the head during running at 3.5 m/s compared with the NLBG during running (p<.05). As the speed increased, there was a statistically significant increase in vertical/resultant acceleration and shock attenuation for both groups. Conclusion: The findings indicated that the runners with low back pain (LBG) experience greater impact and shock attenuation compared with non-low back pain group (NLBG) during fast running. However, it is still inconclusive whether high impact on the lower extremity during running is the main cause of low back pain in the population. Thus, it is suggested that the study on low back pain should observe the characteristics of impact during running with individuals' low back pain experience and clinical symptoms.