• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.251-258
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• 2018

Recently, due to the increase in the traffic volume of vehicle, the collision of the vehicle collision has been increased so that the neck injuries of the passengers has been increased. In order to prevent this, vehicle collision analysis research using computer simulation has been actively carried out in consideration of the design point of car seat. In this study, I used the MADYMO program for analyzing the passenger behavior using a BioRID II dummy, and predicted the neck injuries of passengers according to the change of the backset at the rearward collision of the driving speed of 16km/h. As a result, it was found that the shorter the backset, the shorter the contact start time but the contact completion time was almost the same and the T1 acceleration showed that the acceleration increased with the backset. In addition, the tensile strength increases as the backset increases, and NIC (Neck Injury Criterion) increases as the head speed reaches the headrest.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.30 no.1
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• pp.15-27
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• 2024

Background: This study examined the effects of the muscle energy technique and cervical traction after applying conservative physical therapy to patients with cervical radiculopathy. Methods: Twenty-six patients with cervical radiculopathy were randomized into two groups: the experimental group (n=13) and the control group (n=13). The two groups performed the muscle energy technique and for 4 weeks, 3 times a week, in 70-minute sessions. Pain, range of motion, function, and muscle performance were assessed using the visual analogue scale (VAS), cervical range of motion (CROM) goniometer, neck disability index (NDI), and stabilizer pressure biofeedback, before and after training. Results: After four weeks of therapy, the VAS (p<.001), NDI (p<.01), and the maximum strength of the deep neck flexion muscles significantly decreased (p<.01) and CROM significantly increased in both groups (p<.05). Conclusion: The muscle energy technique and therapeutic modalities such as cervical traction are effective in reducing VAS and NDI and increasing CROM and muscle performance in patients with cervical radiculopathy.

• New & Renewable Energy
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• v.3 no.1 s.9
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• pp.54-59
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• 2007

A sintering aid, $B_{2}O_{3}$ have been included into a $LiAlO_{2}$ electrolyte support by a tape casting method in order to reinforce mechanical strength of the support for molten carbonate fuel cells [MCFCs). Starting idea originates from the low melting point of $B_{2}O_{3}$ ($450^{\circ}C$), which can provide the low temperature consolidation of ceramic materials. The mechanical properties and the microstructure changes of the $B_{2}O_{3}$-included electrolyte support were examined by scanning electron microscope, mercury porosimetry, X-ray powder diffraction [XRD], high temperature differential scanning calorimeter and three-point bending strength measurement. The mechanical strength was clearly improved by addition of $B_{2}O_{3}$. The increase of mechanical strength results from the neck growth of a new $LiAlO_{2}$ phase between $LiAlO_{2}$ particles by the liquid phase sintering. Average pore size and porosity of the electrolyte support reinforced by addition of the sintering aid, $B_{2}O_{3}$, was $0.24{\mu}m$ and 59%, respectively which were suitable microstructure of a matrix for an application of MCFCs.

• Structural Engineering and Mechanics
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• v.64 no.6
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• pp.793-802
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• 2017

The damage of concrete due to the expansion of alkali-aggregate reaction (AAR) and thermal-chemical reactions affecting the strength of concrete is studied. The empirical equations for the variations of expansion of AAR, compressive strength and degradation of the modulus of elasticity with time, and compressive strength with degradation of the modulus of elasticity are proposed by analysing numerous experimental data. It is revealed that the expansion of AAR and compressive strength increase with time. The proposed combination of the time variations of chemical and mechanical parameters provides a satisfactory prediction of the concrete strength. Seismic analysis of the aged Koyna dam is conceded for two different long-term experimental data of concrete incorporating the proposed AAR based properties. The responses of aged Koyna dam reveal that the crest displacement of the Koyna dam significantly increases with time while the contour plots show that major principal stress at neck level reduces with time. As the modulus of elasticity decreases with ages the stress generated in the concrete structure get reduces. On the other hand with lesser value of modulus of elasticity the structure becomes more flexible and the crest displacement becomes very high that cause the seismic safety of the dam reduce.

• Sleep Medicine and Psychophysiology
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• v.12 no.2
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• pp.105-110
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• 2005

The pathogenesis and mechanism of obstructive sleep apnea (OSA) has been under investigation for over 25 years, but its etiology and mechanism remains elusive. Skeletal (maxillary and/or mandibular hypoplasia or retrodisplacement, inferior displacement of hyoid) and soft tissue (increased volume of soft tissue, adenotonsillar hypertrophy, macroglossia, thickened lateral pharyngeal walls) factors, pharyngeal compliance (increased), pharyngeal muscle factors (impaired strength and endurance of pharyngeal dilators and fixators), sensory factors (impaired mechanoreceptor sensitivity, impaired pharyngeal dilator reflexes), respiratory control system factors (unstable respiratory control) and so on facilitate collapse upper airway. Therefore, OSA may be a heterogeneous disorder, rather than a single disease entity and various pathogenic factors contribute to the OSA varies person to person. As a result, patients may respond to different therapeutic approaches based on the predominant abnormality leading to the sleep-disordered breathing.

• Journal of Biomedical Engineering Research
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• v.26 no.2
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• pp.123-127
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• 2005

Compression Hip Screw (CHS) is one of the most widely-used prostheses for the treatment of intertrochanteric fractures because of its strong fixation capability. Fractures at the neck and screw holes are frequently noted as some of its clinical drawbacks, which warrant more in-depth biomechanical analysis on its design variables. The purpose of this study was to evaluate changes in the strength with respect to the changes in design such as the plate thickness and the number of screw holes. Both mechanical test and FEM analysis were used to systematically investigate the sensitivities of the above-mentioned design variables. For the first part of the mechanical test, CHS (n=20) were tested until failure. The CHS specimens were classified into four groups: Group Ⅰ was the control group with the neck thickness of 6-㎜ and 5 screw holes on the side plate, Group Ⅱ 6-㎜ thick and 8 holes, Group Ⅲ 7.5-㎜ thick and 5 holes, and Group Ⅳ 7.5-㎜ thick and 8 holes. Then, the fatigue test was done for each group by imparting 50% and 75% of the failure loads for one million cycles. For the FEM analysis, FE models were made for each group. Appropriate loading and boundary conditions were applied based on the failure test results. Stresses were assessed. Mechanical test results indicated that the failure strength increased dramatically by 80% with thicker plate. However, the strength remained unchanged or decreased slightly despite the increase in number of holes. These results indicated the higher sensitivity of plate thickness to the implant strength. No fatigue failures were observed which suggested the implant could withstand at least one million cycles of fatigue load regardless of the design changes. Our FEM results also supported the above results by showing a similar trend in stress as those of mechanical test. In summary, our biomechanical results were able to show that plate thickness could be a more important variable in design for reinforcing the strength of CHS than the number of screw holes.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.4
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• pp.363-368
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• 2000

The purposes of the study was to examine changes in thickness and strength of the rat femur after administration of sodium fluoride in the drinking water. 48 female Sprague-Dawley rats were randomly divided into 4 groups, and they were supplied with 0(control), 1, 5 and 50 ppm of fluoride in the drinking water ad libitum for 6 weeks. Rats were killed and both sides of femur were dissected. Bone strength was measured as the stress of failure of femur at the middle point and femoral neck with Instron. Histologic slides were prepared from the femur shaft with routine processing of fixing, demineralizing, embedding and HE staining. Thickness and area of cortical bone and medullary cavity were measured by using Camera Lucida and Image Analyzer. All the collected data were analyzed with one-way ANOVA, Duncan's multiple range test for post-hoc tests and ANCOVA using the SAS 6.12 package at the level of 0.05. Bone strength increased significantly in the animals given 1 and 5 ppm of fluoride in the water, as compared to the control group. There were significant decreases of stress at fracture in 50 ppmF group compared to the 1 and 5 ppmF groups. The similar trends of bone strength at the femoral neck fracture test, but there were no statistical significances. Cortical bone thickness and area of the femur increased in the 1 and 5 ppmF groups compared to the control. However, the thickness of 50 ppmF group also decreased significantly as compared to 1 and 5 ppmF groups. On the other hand, medullary thickness and area increased in all fluoride groups than control group. All of the findings presented support the conclusion that, low fluoride dosage used in water fluoridation could increase the bone strength and might have preventive effect on femur fracture.

• Journal of Korean society of Dental Hygiene
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• v.13 no.1
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• pp.114-121
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• 2013

Objectives : The purpose of the research is to measure Dental Hygiene students' level of musculoskeletal pain before and after receiving scaling training which involves repetitive operations and examine effects the operations have on the students' grip and pinch strength. Methods : 15 subjects in Dental Hygiene at Y university located in Chungbuk were tested on November 2, 2011. Results : 12 students had a musculoskeletal pain before receiving scaling training. However, all the 15 students had a musculoskeletal pain after the training. Body part the largest number of the students complained of the pain on was shoulders(37.9%) followed by neck(20.8%), waist(13.9%), wrists(10.3%), then back(6.9%) before receiving the training. Then the result showed that shoulders are where the largest number of students(24.1%) felt the pain, followed by neck(17.2%), wrists and fingers(13.8%), waist(12.1%), back and lower arms(6.9%), then palms(5.2%) after the training. Visual Analogue Scale(VAS) increased to $6.35{\pm}2.09$ after receiving the training from $3.31{\pm}3.38$ and this shows statistically significant difference(p<.001). Upon inspection, average grip strength decreased to $23.23{\pm}5.79kg$ from $25.00{\pm}4.51kg$ after receiving the training and this shows statistically significant difference(p<.05). Key pinch was the strongest among the three pinch strengths followed by tripod pinch then tip pinch. Average of all the three pinch strengths showed to have statistically significant difference before and after the training(p<.05); Tip pinch from $6.53{\pm}1.36$ to $5.87{\pm}1.3$, key pinch from $13.47{\pm}2.5$ to $12.53{\pm}2.30$, and tripod pinch from $9.27{\pm}3.04$ to $8.03{\pm}2.72$. Conclusions : The result showed that scaling training has effects on Dental Hygiene students' musculoskeletal subjective symptoms and their grip and pinch strength changes after receiving the training.

• Journal of Community Nutrition
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• v.1 no.2
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• pp.98-107
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• 1999

The purpose of this study was to investigate Bone Mineral Density(BMD) and affecting factors on BMD of college women in Seoul. The subjects were 47 healthy college women aged 18-25 years. Antrophometric and body fat measurements were performed by Bioelectrical Impedance Fatness Analyzer(Tanita TVF 202). Blood pressure and pulse frequency were measured. Dietary intakes and general living habits were examined through questionnaires and nutrient intakes were analyzed by Computer Aided Nutritional Analysis(CAN) program for professional. Serum total cholesterol, TG(triglyceride), HDL-cholesterol, total protein, albumin, GOT, calcium were measured by Spotchem(SP-4410). Serum osteocalcin and alkaline phosphatase(ALP) were measured to monitor bone formation. BMD of lumbar spine(L2-L4), right hip(neck, ward's triangle, trochanter) and right forearm were measured by Dual Energy X-ray Absorptiometry(DEXA). Muscle strength was measured by examining leg flexion strength(right and left), leg extension power(right and left), handgrip power(right and left) and back strength. All data were statistically analyzed by the SAS PC package program. BMD of college women was normal(by WHO, 1994). Their muscle strength was bad(by national fitness guidebook, 1995). Only a mall number of them exercised (32.6% of subjects). There was no significant difference among BMD, muscle strength and % body fat(p<0.05). There were significant differences between BMD and total cholesterol as well as TG and VLDL-cholesterol(p<0.05). Total cholesterol was associated with decreasing BMD of the right forearm(p<0.05). TG and VLDL-cholesterol are associated with increasing BMD of right hip ward's triangle(p<0.05). There were significant differences among BMD, ALP and serum total protein. ALP was associated with decreasing BMD of the right forearm(p<0.05). There were significant differences between BMD and Ca as well as between Na and K intakes (p<0.05). Intakes of Na and K were associated with decreasing BMD of the right forearm (UD)(p<0.05). There were significant differences between in BMD and pulse frequently and serum albumin (p<0.05). Serum albumin is associated with increasing BMD of L3-L4(p<0.05), right hip neck(p<0.05). %Body fat, TG, VLDL-C, Ca intake, pulse frequency and serum albumin were associated with increasing BMD(p<0.05). Intakes of Na and K, ALP, total cholesterol, total cholesterol, total protein and height are associated with decreasing BMD(p<0.05). Overall results indicate that Ca intake but to be moderate in protein and Na intakes in order to increase BMD. Body exercise was recommended to increase BMD as well.

• Journal of Korean Foot and Ankle Society
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• v.17 no.2
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• pp.106-114
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• 2013

Purpose: Posteroanterior screw fixation is biomechanically stronger than anteroposterior screw fixation. However, there are few literature about the correlation between clinical results and more strength by posteroanterior fixation. This study was performed to evaluate the clinical outcomes of the accelerated rehabilitation following anterior open reduction and posterior percutaneous screw fixation for displaced talar neck fractures. Materials and Methods: Eighteen cases were followed up for more than 1 year after posteroanterior fixation using headless compression screw for talar neck fractures. The clinical evaluation was performed according to American Orthopaedic Foot and Ankle Society (AOFAS) score and Hawkins criteria. As radiographic evaluation, the degree of fracture displacement, period to union, and occurrence rate of complications such as avascular necrosis through MRI were measured. Results: The AOFAS score was average 90.4 points at the last follow-up. There were 7 excellent, 9 good, and 2 fair results according to the Hawkins criteria. Therefore, 16 cases(88.8%) achieved satisfactory results. The degree of fracture displacement had improved significantly from preoperative average 5.6 mm to 1.2 mm immediate postoperatively, and maintained to 1.1mm at the last follow-up. All cases achieved bone union, and the period to union was average 12.4 weeks. There were 3 cases of avascular necrosis of talar body and 2 cases of post-traumatic arthritis. Conclusion: Anterior open reduction and posterior percutaneous headless screw fixation seems to be an effective surgical method for displaced talar neck fractures, because of the possibility of accurate restoration of articular surface, fixation strength enough to early rehabilitation, and needlessness of hardware removal.