• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.214-219
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• 2021

Objective: The aim of this study was to evaluate the differences in muscle activity of hamstring muscle depending on the position of the feet during Swiss ball hamstring curl exercise. Method: Total of 15 male participants with no history of hamstring muscle injuries and musculoskeletal disorders in the past 6 months were participated in this study (Age: 29.27 ± 4.96 yrs, Height: 173.47 ± 5.18 cm, Body mass: 75.47 ± 12.50 kg). The muscle activation of semitendinosus and biceps femoris with four different feet positions including neutral stance, internal rotation, external rotation, and wide stance were measured during a Swiss ball hamstring curl exercise. For the analysis, the Swiss ball exercise movement comprised of 3 events (90°→ 0°→ 90°) based on the knee angle and 2 phases relative to the mechanism of muscle contraction (eccentric/concentric contraction). To pursue the study goal, an one-way ANOVA with repeated measures was performed with statistical significance as α = 0.05. Results: There was no statistically significant feet position effect found during the Swiss ball hamstring curl with eccentric contraction phase (p>.05). It is, however, semitendinosus showed an enhanced muscle activation in concentric contraction phase, displaying the highest muscle activity in wide stance and the lowest in external rotation (p<.05). Conclusion: Our findings suggest that this exercise can be beneficial in selectively training the semitendinosus. In other words, Swiss ball hamstring curls performed in wide stance strengthens semitendinosus, which improves the stability of knee and are effective in preventing knee injuries and reinforces rehabilitation.

• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.141-149
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• 2021

3D printers, which emerged in the late 20th century, have become a key part of the fourth industrial revolution in the 21st century. Although 3D printers, the key equipment of the maker movement and the starting point of the new cottage industry in the 21st century, still reveal the limitations of mass production with low output speed and limited filament materials, the use of 3D printers by ceramic craftsmen has recently increased exponentially. However, as part of a way to overcome the discord between craftsmanship and the new technology, which has been repeated over and over in the past in craft history, the study focused on the 'plaster mold casting' technique using 3D printers. Therefore, after analyzing casting techniques of Tony Hansen, Webe van Gansbeck, Jade Crompton, and Ryu Hee-do, the potters who actively developed gypsum techniques in the world's ceramic crafts field and applied them to their own designs, I tried to find the point of convergence between 3D printers and ceramic crafts by presenting examples of effective 3D modeling methods and optimal slip casting methods using 3D printers.

• PNF and Movement
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• v.18 no.3
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• pp.415-424
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• 2020

Purpose: This study aimed to compare changes in abdominal muscle thickness in different standing postures with a handheld load between subjects with and without chronic low back pain (CLBP). Methods: Twenty subjects with CLBP and 20 controls participated in this study. Ultrasound imaging was used to assess the changes in the thickness of the transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles. Muscle thickness in three different standing postures (standing at rest, standing with loads, standing with lifting loads) was compared with the muscle thickness at rest in the supine position and was expressed as a percentage of change in the thickness of the muscle. Results: While standing with loads, the change in IO muscle thickness in the CLBP patients increased more significantly than in the pain-free controls (p < 0.05). The standing with lifting loads posture showed a significant increase in the change in thickness of the TrA compared with the standing with loads posture (p < 0.05). In addition, the standing with lifting loads posture showed a significant decrease in the change in the thickness of the EO when compared with the standing with loads posture (p < 0.05). Conclusion: The automatic activity of the IO muscle in subjects with CLBP increased more than that of the pain-free controls in the standing with loads posture. These findings suggest that IO muscle function may be altered in those with CLBP while standing with loads. Additionally, TrA the activation level was found to be associated with increased postural demand caused by an elevated center of mass.

• Journal of Korean Foot and Ankle Society
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• v.25 no.4
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• pp.185-189
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• 2021

An aneurysmal bone cyst (ABC) can occur in many parts of the human body, but a primary ABC of the talus is extremely rare. ABCs are benign, but aggressively growing tumors that usually occur in the first two decades of life. Patients mainly complain of pain, limited movement of the involved joint or a palpable mass. Pain may worsen suddenly because of pathological fractures. If not treated properly, ABC has a risk of local recurrence, followed by the destruction of the joint and a significant functional deficit. While the complete removal of the bone tumor is essential, it is also important to treat the resultant bone defect after removal. The talus has an important part to play in weight-bearing. Therefore, an appropriate bone graft is required for large bone defects that occur after an ABC removal from the talus. We report a primary ABC of the talus in a 28-year-old male that was treated by curettage and a bone pillar pattern graft of autologous tricortical iliac crest bone. The patient had an excellent functional outcome with early weight-bearing, and there was no recurrence at 16 months of follow-up.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.597-604
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• 2009

The mass transit networks in Korea, such as buses, metro and subway, are co-related and the number of transfer points, in which a lot of pedestrian movement is generated, are rising. The functions of the transfer centers, in which several travel modes cross at a point, have to include convenience and comfort for pedestrians using the transfer centers, and such functions can make transit a more attractive travel option and thus eventually contribute to increases in ridership. However, the guidelines for station layouts and their assessments in transfer stations are not suggested so far. So the pedestrian pattern data (pedestrian walking distances and times, pedestrian approaching distances and times, pedestrian walking paths in the inside of stations) was collected and analyzed. Based on the results of the analysis, the ways to measure the quality of comfort for those who using transfer facilities were suggested using the times that pedestrians consume to transfer from a travel mode to another. The walking time of pedestrians at the inside of stations was also measured by pre-selected pedestrian pathways as the guidelines for station layout assessment in transfer facilities.

• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.175-184
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• 2023

Objective: The purpose of this study is to investigate the effects of human motion and javelin kinematics during the energy transfer in javelin throwing on records, and to provide evidence-based training insights for athletes and coaches to enhance records. Method: Three javelin throw athletes (age: 22.67 ± 0.58 years, height: 178.33 ± 7.37 cm, weight: 83.67 ± 1.15 kg) were recruited for this study. Each athlete attempted ten maximum record trials, and the kinematic data from each performance were analyzed to determine their influence on the records. The Theia3d Markerless system was used for motion analysis. Results: Key factors were modeled and identified at each moment. In E1, main variables were COM Y (𝛽 8.162, p<.05) and COM velocity Z (𝛽 -72.489, p<.05); in E2, COM X (𝛽 -17.604, p<.05); in E3, COM X (𝛽 -18.606, p<.05), COM velocity Y (𝛽 38.694, p<.05), and COM velocity X (𝛽 66.323, p<.05). For the javelin throw dynamics in E3, key determinants were Attitude angle and Javelin velocity in the Y-axis. Conclusion: The study reveals that controlled vertical movement, center of mass management during braking, and enhanced pelvic rotation significantly improve javelin throw performance. These kinematic strategies are critical for record enhancement in javelin throwing.

• PNF and Movement
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• v.22 no.1
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• pp.101-111
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• 2024

Purpose: The purpose of this study was to investigate physical activity as a risk factor for neck pain recurrence using the National Health Insurance Data Sharing Service that utilizes a nationwide cohort in South Korea. Methods: Medical records spanning a two-year period were extracted from the National Health Insurance database for 541,937 patients who sought healthcare services for neck pain (ICD 10 codes: M54.2) in 2020 and completed the national health examination survey. Selected variables for analysis included age, gender, health insurance premium decile, regional health vulnerability index, body mass index (BMI), acuity, blood pressure, and types of physical activity. A mixed-effect multivariate logistic regression analysis was conducted to examine the recurrence rate of neck pain and identify risk factors for neck pain recurrence. Results: Among the participants, 124,433 patients (23.0%) experienced a recurrence of neck pain within two years, with higher recurrence rates observed among older individuals and females. Regression analysis revealed that the risk of neck pain recurrence increased with age (OR=1.51), being female (OR= 1.10), being a medical aid recipient (OR=1.51), and having anaerobic (OR=1.04) or vigorous physical activities (OR=1.06). By contrast, an increased health insurance premium decile (OR=0.96) and having moderate physical activity (OR=0.97) were associated with a decreased risk of neck pain recurrence. Conclusion: This study highlights the importance of moderate physical activity as an effective strategy for reducing the recurrence of nonspecific neck pain, underscoring the necessity for personalized physical activity programs for patients.

• Fashion & Textile Research Journal
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• v.26 no.1
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• pp.123-136
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• 2024

This study aimed to assess the mobility and thermal comfort of personal protective equipment (PPE) among female healthcare workers, taking into account wearers' physique and PPE protection levels. A total of 16 participants (age: 26.3 ± 8.3 y, height: 161.5 ± 7.3 cm, body weight: 57.1 ± 11.0 kg, BMI: 21.9 ± 3.6), representing diverse body types, underwent four PPE conditions: L (Low_Plastic gown ensemble), M (Medium_Tyvek 400), H (High_Tyvek 800J with Powered Air Purifying Respirator [PAPR]), and E (Extremely high_Tychem 2000 with PAPR, Bib apron, and Chemical-resistant gloves). The mobility protocol consisted of 10 different tasks in addition to donning and doffing. The 10 tasks were repeated twice at an air temperature of 24.3 ± 0.1℃, 59±4%RH. Findings revealed a disproportionate relationship between PPE protection and wearer discomfort. Significant differences in clothing microclimate and total sweat rate were observed between the lowest (L) and highest (E) protection levels (p < 0.01), while distinctions among medium levels were inconclusive. Subjective evaluations favored conditions H and L over M and E (p < 0.05), indicating reduced heat, and humidity, increased comfort, and lower exertion. Instances of mobility discomfort, specially in the small body type group, underscored the need for a suitable PPE size system for Korean adult female medical workers. Furthermore, enhancements in gloves, shoe cover, and PAPR hood designs are essential for improving ease of movement and preventing hindrance.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.67-83
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• 2008

To find out the process of hillslope denudation since the Last Glacial Maximum in Asan area, we conducted the stratiform interpretation and carbon age measurements with the collected samples through trenching in the valley bottom of 'Agol' located in the lower stream of Magok stream. The results are as follows. 11 inorganic and 8 organic matter layers were confirmed at the point of trench MG1 in the subject area, 7 inorganic and 3 organic at the point of trench MG2, and 5 inorganic and 3 organic at the point of trench MG3, respectively. The frequency of hillslope denudation, hillslope mass movement, which had occurred in the unstable environment of back hillslope at the point of MG 1, was 11 times (8 times before about 2,900yrBP, twice in between about 2,900~1,900yrBP, and once after about 1,900yrBP) as a whole. The frequency of moor which had formed in the comparatively stable environment of back hillslope was 9 times (5 times before about 3,000yrBP, twice in between 3,000~2,800yrBP, and once in between 2,200~1,900yrBP) at minimum. The frequency of back hillslope denudation at the point of MG2 was totally 7 times (4 times before about 1,900yrBP and 3 times after about 1,900yrBP) and the moor formations were 3 times (twice before about 1,900yrBP and once after 1,900yrBP). The frequency of back hillslope denudation at the point of MG3 was totally 5 times (3 times before about 1,900yrBP and twice after about 1,900yrBP) and the moor formations were 3 times (twice before about 1,900yrBP and once after 1,900yrBP). The hillslope surrounded by valley bottom of 'Agol' was confirmed as the pile up of various inorganic matters by the mass movement such as sand or sandy gravel in the valley bottom of the subject area, formed not once but several times of denudation. We could know that the hillslope denudation cycle converged to the time period of $10^2{\sim}10^3$ years. These results will be an important basic data for restoring hillslope denudation process near Asan and changing climate of the Late Quaternary Period.

• Journal of Life Science
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• v.21 no.1
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• pp.1-8
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• 2011

The purpose of this study was to investigate whether 12-weeks of movement training would increase the psoas major cross-sectional area (CSA) in senior men and women. Fifty eight men and women aged 65 to 80 years old ($69.6{\pm}3.7$, 30 male, 28 female) were divided into a control (n=19) and exercise group (n=39). Subjects were assessed before and after the training program for stature, body mass, and magnetic resonance imaging of the psoas major and the quadriceps muscle. The experimental group performed exercises using machines designed to improve the movement of the hip at a frequency of twice every week, with a total of 23 trainings in 12-weeks. Magnetic resonance images of both thighs and the abdomen and psoas major were obtained, aimed at 50% of the length of the greater trochanter and the lower edge of the femur and between the fourth (L4) and fifth (L5) lumbars. A 9.4% increase in the psoas major CSA in the training group was observed. In the male and female breakdown, a 11.5% and 8.4% change was observed in males and females, respectively. In the quadriceps, there was no significant statistical improvement in either males or females. Furthermore, in the control group, there was no significant change seen in either the psoas major or the quadriceps. As a result of conducting training that enables upkeep of posture and smooth linkage of the lumbar spine, the pelvis and thighbone, the psoas major CSA of older adults were improved in a short period of time. For this reason, the possibility of improving the psoas CSA, which decreases remarkably with increased age, by improving the linkage of the body trunk is also suggested.