• The Korea Journal of Herbology
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• v.20 no.4
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• pp.83-94
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• 2005

Objectives : The present study attempted to reveal the effects of Morindae Radix extracts on the sciatic nerve neurectomized osteoporotic ddy mice model. Methods : Thickness of hind limbs and their differences, absolute and relative tibia weight and thickness, bone failure load, bone mineral density (BMD), histomorphometrical index, serum osteocalcin level, tibia calcium and phosphorus contents were monitored. Results : In sciatic neurectomized mice, thickness of hind limb, absolute and relative weights, thickness, failure loads, BMD of tibia, trabecular bone volume (TBV), thickness of trabecular bone and cortical bone thickness, length were significantly decreased. However, these changes of those dose-dependently reduced in MR extract-dosing group. Conclusions : it is considered that MR extracts have some favorable effect to prevent, the osteoporosis induced by sciatic neurectomy. However, the exact mechanism and the possibility of MR extract were remains unknown. In addition, the potential toxicity of these MR extracts were also unknown. So the further studies were needed about toxicological and pharmacological aspects.

• Journal of Korean Biological Nursing Science
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• v.3 no.2
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• pp.91-103
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• 2001

The bone is composed of the bone matrix of collagen and hydroxyapatite, the mixture of calcium and phosphours. The bone tissue is considered to the special connective tissue that possesses extracellular matrix made by collagen fiber deposited with mineral complex. In order to maintain bone mass measured by the sum of bone matrix and hydroxyapatite, bone resorption by osteoclast during lifetime and bone remodeling to form bone by osteoblast in its resorption region repeat continuously. The osteoblast has a mesodermic fetal origin like fibroblast for the formation of form tissues. Two cells express identical genes and synthesize the identical collagen type I as the major component of the formation of bone matrix and skin. Therefore, it is considered that the decrease of skinfold thickness and the decrease of bone mass related to the age, the change of two tissues composed of collagen type I is caused by the same genetic mechanism. The decrease of bone mass is caused by the change of the amount and structure of bone matrix by several factors and the amount of minerals deposited on bone matrix. Especially, in case of female, the deficiency of estrogen by menopause makes these changes rapidly increased. The decrease of bone mass and skinfold thickness is due to the decrease of the amount of collagen and its structural change the common component of bone tissue and skin tissue. Therefore, the relationship of the amount of cross-linked peptide N-telopeptide, collagen metabolite which excretes as urine. Based upon the proved results about the significant relationship of bone mass, the amount of bone collagen, the amount of skin collagen and skinfold thickness, the bone mass may be expected through a facile determination of skinfold thickness.

• Tribology and Lubricants
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• v.34 no.3
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• pp.93-107
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• 2018

The purpose of Part I of this study is to find the potential region of wear scarring on engine journal bearings operating at a constant angular crank shaft velocity under firing conditions. To do this, we calculate the applied loads and eccentricities of a big-end journal bearing installed on a four-stroke and four-cylinder engine at every crank angle. Then, we find potential wear regions, such as a minimum oil film thickness, at every crank angle below most oil film thickness scarring wear (MOFTSW) obtained based on the concept of the centerline average surface roughness. Thus, the wear region is defined as a set of each film thickness below the MOFTSW at every crank angle. In this region, the wear volume changes according to the wear depth and wear angle, depending on the minimum oil film thickness at every crank angle. The total wear volume is the summation during one cycle. Graphical views of the region in the two-dimensional coordinates show the crank angle and bearing angle along the journal center path, indicating the position of the minimum oil film thickness. The results of wear analysis show that the possible wear region is located at a few tens of angles behind the upper center of a big-end bearing at maximum power rpm.

• Korean Journal of Materials Research
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• v.25 no.1
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• pp.16-20
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• 2015

In this study, in order to improve the efficiency of n-type monocrystalline solar cells with an Alu-cell structure, we investigate the effect of the amount of Al paste in thin n-type monocrystalline wafers with thicknesses of $120{\mu}m$, $130{\mu}m$, $140{\mu}m$. Formation of the Al doped $p^+$ layer and wafer bowing occurred from the formation process of the Al back electrode was analyzed. Changing the amount of Al paste increased the thickness of the Al doped $p^+$ layer, and sheet resistivity decreased; however, wafer bowing increased due to the thermal expansion coefficient between the Al paste and the c-Si wafer. With the application of $5.34mg/cm^2$ of Al paste, wafer bowing in a thickness of $140{\mu}m$ reached a maximum of 2.9 mm and wafer bowing in a thickness of $120{\mu}m$ reached a maximum of 4 mm. The study's results suggest that when considering uniformity and thickness of an Al doped $p^+$ layer, sheet resistivity, and wafer bowing, the appropriate amount of Al paste for formation of the Al back electrode is $4.72mg/cm^2$ in a wafer with a thickness of $120{\mu}m$.

• Nuclear Engineering and Technology
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• v.27 no.2
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• pp.226-233
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• 1995

The wall thickness of a pressure tube is increased in order to reduce the probability of failure in a pressure tube of CANDU type reactor. It is presented here that the variation of wall thickness changes stress, hydrogen concentration and delayed hydride cracking in Zr-2.5Nb pressure tube. When the wall thickness is increased from 4.2 mm to 5.2 mm, the stress exerted on the tube and the deuterium taken up during operation are reduced by 19％. Further, the calculated allowable depth of the surface flaw over which delayed hydride cracking(DHC) is susceptible increases by 50％. DHC initiation is controlled by the stress and by the hydrogen concentration in the pressure tube. The results are therefore very significant in such a respect that increased wall thickness may reduce DHC initiation. Ac the wall thickness increases the hydrostatic tension will increase. Its impact on the acceleration of the crack growth rate of DHC deserves further studies.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.3
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• pp.319-327
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• 2012

Purpose : This study aimed to identify the asymmetry observed in the rehabilitative ultrasound imaging of lateral abdominal muscle thickness and performance between the affected and unaffected side during the abdominal drawing-in maneuver (ADIM), an exercise used to facilitate activation of selectively TrA to stabilize the trunk prior to limb movement. Methods : The Participants were twenty one patients with post-stroke hemiplegia in this study. Ultrasound imaging was used to measure amount of changes in thickness of the external oblique (EO), internal oblique (IO), transversus abdominis (TrA). A Paired t-test was used to compare relaxed muscle thickness to contracted muscle thickness of all 3 muscles between the affected and unaffected sides. Results : The outcome measures included side to side differences of absolute thickness, contraction ratio among the lateral abdominal muscles. There was no significantly difference in between the affected and unaffected side at rest. But, there was a significantly difference in absolute muscle thickness between the affected and unaffected side of only TrA muscle. Also contraction ratio was a significantly difference between the affected and unaffected TrA muscle. Conclusion : These findings support the asymmetrical activation of TrA muscle during abdominal muscle contraction in patients with post-stroke hemiplegia. Further studies are warranted for confirming this outcome.

• PNF and Movement
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• v.17 no.2
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• pp.293-302
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• 2019

Purpose: The purpose of this study was to investigate the effects of plank exercises involving the contraction of the adductor muscle of the hip joint on core muscle thickness and to propose an effective plank exercise method. Methods: A total of 30 healthy young adults (17 males, 13 females) voluntarily participated in the study. The subjects were randomized to the prone plank exercise with hip adductor contraction (n=10), the prone plank exercise (n=10), and the supine plank exercise (n=10) groups. Muscle thickness measurements were taken prior to starting the exercise program and after completing the program at the end of a 4-week period. The muscle thickness of the rectus abdominis (RA), multifidus (MF), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) muscles were measured using ultrasonography. Each group performed the stipulated plank exercise five times a week as follows: 5 sets of 20 seconds during the first week, 5 sets of 30 seconds in the second week, 5 sets of 40 seconds in the third week, and 5 sets of 40 seconds in the last week. Results: The three different types of plank exercises all showed significantly increased thickness of the RA, MF, EO, IO, and TrA (P<0.05). Furthermore, changes in the thickness of both the MF and TrA were statistically more significant in the groups that did the prone plank exercise with the hip adductor contraction and the supine plank exercise than in the prone plank exercise group (P<0.05). Conclusion: The study results suggest that the prone plank exercise with hip adductor contraction is a more effective method for overall activation of the RA, MF, EO, IO, and TrA than the prone plank exercise and the supine plank exercise.

• Journal of Korean Neurosurgical Society
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• v.65 no.1
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• pp.13-21
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• 2022

Objective : Nontraumatic subdural hematoma (SDH) is a common disease, and spinal cerebrospinal fluid (CSF) leakage is a possible etiology of unknown significance, which is commonly investigated by several invasive studies. This study demonstrates that heavily T2-weighted magnetic resonance myelography (HT2W-MRM) is a safe and clinically effective imaging modality for detecting CSF leakage in patients with nontraumatic SDH. Methods : All patients who underwent HT2W-MRM for nontraumatic SDH workup at our institution were searched and enrolled in this study. Several parameters were measured and analyzed, including patient demographic data, initial modified Rankin Scale (mRS) score upon presentation, SDH bilaterality, hematoma thickness upon presentation, CSF leakage sites, treatment modalities, follow-up hematoma thickness, and follow-up mRS score. Results : Forty patients were identified, of which 22 (55.0%) had CSF leakage at various spinal locations. Five patients (12.5%) showed no change in mRS score, whereas the remaining (87.5%) showed decreases in follow-up mRS scores. In terms of the overall hematoma thickness, four patients (10.0%) showed increased thickness, two (5.0%) showed no change, 32 (80.0%) showed decreased thickness, and two (5.0%) did not undergo follow-up imaging for hematoma thickness measurement. Conclusion : HT2W-MRM is not only safe but also clinically effective as a primary diagnostic imaging modality to investigate CSF leakage in patients with nontraumatic SDH. Moreover, this study suggests that CSF leakage is a common etiology for nontraumatic SDH, which warrants changes in the diagnosis and treatment strategies.

• Journal of Biomedical Engineering Research
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• v.43 no.3
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• pp.177-184
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• 2022

The purpose of this study was to present the IMU sensor based trunk stabilization exercise and to evaluate the changes in the muscle activity and thickness with non-specific low back pain patients (N=30). They were classified into two groups; lumbar stabilization exercise using IMU sensor (ILS), (n₁=20) and general lumbar stabilization exercise (GLS), (n₂=10). By comparing the difference between pre and post intervention via trunk muscle activity and muscle thickness, the significant differences were identified. Muscle activity was measured on external oblique (EO), internal oblique (IO), and multifidus (MF) by using surface electromyography (sEMG). Muslce thickness was measured on external oblique, internal oblique, transverse abdominis (TrA), and multifidus (MF) by using ultrasonography. sEMG activity was recorded at right side-bridge position. Each group performed the proposed lumbar stabilization exercise for 30 minutes a day, 5 times a week for 4 weeks. Trunk muscle activity was observed with a significant increase in the IO of ILS (p<.05) and a decrease in the MF of GLS (p<.05). Trunk muscle thickness was significantly increased in left EO and both IO of GLS (p<.05), and also significant increased right EO, both IO, both TrA, and both MF of the ILS (p<.05). In the future, a convergence approach of rehabilitation and engineering is needed to select a sensor suitable for rehabilitation purposes, study the validity and reliability of data, and produce appropriate rehabilitation contents.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3260-3267
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• 2023

Zr-Nb alloy have been widely used as fuel rods in nuclear power plants. However, from the Fukushima nuclear accident, the weakness of the rod was revealed under harsh conditions, and research on the safety of these types of rods was conducted after the disaster. The method of depositing chromium onto the existing Zr-Nb alloy fuel rods is being considered as a means by which to compensate for the weakness of Zr-Nb alloy rods because chromium is strong against oxidation at high temperatures and has high strength. In order to secure these advantages, it is important to maintain the Cr thickness of the rods and properly inspect the rods before and during their use in power generation. Eddy current testing is a typical means of evaluating the thickness of thin metals and detecting surface defects. Depending on the size and shape of the inspected object, various eddy current sensors can be applied. In particular, because pancake sensors can be manufactured in very small sizes, they can be used for inspections even in narrow spaces, such as a nuclear fuel assembly. In this study, an eddy current technique was developed to confirm the feasibility of Cr coating thickness evaluations. After determining the design parameters of the pancake sensor by means of a FEM simulation, a FPCB pancake sensor was manufactured and the optimal frequency was selected by measuring minute changes in the Cr-coating thickness using the developed sensor.