• The korean journal of orthodontics
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• v.53 no.3
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• pp.205-216
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• 2023

Objective: To investigate changes in the immature teeth of Sprague-Dawley rats during orthodontic treatment and to explore the changes in the peri-radicular alveolar bone through micro-computed tomography (CT). Methods: Twenty-five 26-day-old male Sprague-Dawley rats were included. The maxillary left first molar was moved mesially under a continuous force of 30 cN, and the right first molar served as the control. After orthodontic treatment for 7, 14, 21, 28, and 42 days, the root length, tooth volume, and alveolar bone mineral density (BMD) around the mesial root were measured through micro-CT. Results: The immature teeth continued to elongate after application of orthodontic force. The root length on the force side was significantly smaller than that on the control side, whereas the differences in the volume change between both sides were not statistically significant. Alveolar bone in the coronal part of the compression and tension sides showed no difference in BMD between the experimental and control groups. The BMD of the experimental group decreased from day 14 to day 42 in the apical part of the compression side and increased from day 7 to day 42 in the apical part of the tension side. The BMD of the experimental group decreased in the root apex part on day 7. Conclusions: The root length and volume of immature teeth showed continued development under orthodontic forces. Alveolar bone resorption was observed on the compression side, and bone formation was observed on the tension side.

• Journal of Applied Biological Chemistry
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• v.51 no.3
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• pp.83-87
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• 2008

Tension wood, a specialized tissue developed in the upper side of the leaning stem and drooping branches of angiosperm, is an attractive experimental system attractive for exploring the development and the biochemical pathways of the secondary cell wall formation, as well as the control mechanism of the carbon flux into lignin, cellulose, and hemicellulose. However, the mechanism underlying the induction and the development of the tension wood is largely unknown. Recently, several researchers suggested the possible roles of the plant growth hormones including auxin, gibberellin, and ethylene mainly based on the expression pattern of the genes in this specialized tissue. In addition, expressed sequence tag of Poplar and Eucalyptus provide global view of the genetic control underlying the tension wood formation. However, the roles of the majority of the identified genes have not yet been clearly elucidated. The present review summarized current knowledge on the biosynthesis of tension wood to provide a brief synopsis of the molecular mechanism underlying the development of the tension wood.

• Journal of the Korea Furniture Society
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• v.12 no.1
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• pp.47-55
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• 2001

Violin bridge blank cut from maple wood with good quality has typical pattern of the radial direction in the side edge with minimal dispersion. This experimental study was designed and carried out to examine the effect of the physical and macroscopical characteristics on the compressive creep of violin bridge blank which had been imported from European manufacturer. This research arose from the idea that the maple solid wood with heterogeneous wood density and ray direction in the side edge would have uneven rheological property of violin bridge blank which is supposed to be pressed by the tension of strings. Experimentally, the compressive creep of bridge blank became smaller with the higher density of imported maple wood and showed clear density-dependence for the duration of load under the string tension of 5 kgf. Every bridge blank showed the behavior of primary creep stage(stress stabilization) having logarithmic regression creep curve with high correlation coefficient under the designed stress level. Even though the relationship between compressive creep and ray direction on the side edge of bridge was not so clear contrary to expectation, we could conclude that wood density and ray direction should be the quality decisive factors affecting the acoustical characteristics and performance of the bridge, the core member of violin-family bow instruments.

• Structural Engineering and Mechanics
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• v.9 no.5
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• pp.491-504
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• 2000

A convenient method for enhancing the strength and stiffness of existing reinforced concrete beams is to bond adhesively steel plates to their tension faces. However, there is a limit to the applicability of tension face plating as the tension face plates are prone to premature debonding and, furthermore, the addition of the plate reduces the ductility of the beam. An alternative approach to tension face plating is to bond adhesively steel plates to the sides of reinforced concrete beams, as side plates are less prone to debonding and can allow the beam to remain ductile. Debonding at the ends of the side plates due to flexural forces, that is flexural peeling, is studied in this paper. A fundamental mathematical model for flexural peeling is developed, which is calibrated experimentally to produce design rules for preventing premature debonding of the plate-ends due to flexural forces. In the companion paper, the effect of shear forces on flexural peeling is quantified to produce design rules that are applied to the strengthening and stiffening of continuous reinforced concrete beams.

• The Journal of Korean Physical Therapy
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• v.30 no.4
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• pp.108-111
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• 2018

Purpose: This study examined the effects of the forward head posture and tension type headache on neck movement among office workers. Methods: The subjects were 6 male and 21 female patients composed of a forward head posture group, forward head posture group with a tension type headache and a normal group. Each group consisted of 2 males and 7 females. The cranio-vertebral angle of the head and the angle of motion of the neck were measured. SPSS 23.0 was used for data analysis and one-way ANOVA was performed for the mean comparison of the neck movements in the three groups. Results: The participants had a limitation in the movement of all necks between the forward head posture group and forward head posture with tension type headache group compared to the normal subjects. The forward head posture with tension headache group had limited neck extension and lateral bending compared to the forward head posture group. Conclusion: Office workers have limitations in the movement of the neck when they are accompanied by forward head posture and tension headache. In particular, when accompanied with a tension headache, there is a restriction on the neck extension and side bending. This study is expected to provide basic data for the relief of tension headache and the treatment of forward head posture in office workers.

• Journal of the Korean Wood Science and Technology
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• v.17 no.3
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• pp.20-27
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• 1989

This experiment was made to find the peripheral variations of annualring widths, the cell dimensions, microfibril angles and bulk densities within each annual-ring of horizontal-growing young tree of beech(Betul a platyphylla var. japonica) and Oak (Quercus variabilis) from the tension to the opposite side. Also a comparision between the features of the obnormal annual ring for horizontal-growing year and normal annual ring for the straight-growing years was made. The dimension of propotion of the element, the microfibril angles and the bulk density decreased or increased continuously toward opposite side which showed minimum or maximum value. The dimension of elements the microfibril angles and the bulk density decreased or increased continuously towards opposite side which showed minimum or maximum value. The dimension of elements. the microfibril angles and the bulk density in the normal annual rings were similar to those in the lateral woods. whereas were significantly more different in the tension wood than in the opposite wood. The features of typical opposite wood in the hardwoods were influenced by the locations within the inclined stems than effects of the decrease in the annual ring width. The oppostie woods in hardwoods did not conform to the tension wood and lateral wood. The abnormal annual ring included the opposite wood, lateral wood similar to normal wood and tension wood having specialized structure even in the same annual ring.

• The korean journal of orthodontics
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• v.20 no.2
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• pp.247-266
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• 1990

The alveolar bone remodeling is essential in tooth movement by orthodontic forces. The collagen and chondroitin sulfate are acting as an important roles in bone remodeling. This study was performed to measure out the quantity of the collagen and chondroitin sulfate in the alveolar bone of rats applied by experimental orthodontic forces. The 150 Sprague-Dawley male rats were divided into the $PGE_2$ treated group, indomethacin treated group and the normal group. A 80gm force rubber band was used as a orthodontic appliance between upper incisors and right upper 1st molar, and left side of experimental rats with no appliance was regarded as a control side. The samples of alveolar bones were obtained from pressure and tension sites in all three groups. respectively, and in control sides, too. The results were as follows. 1. The change in total collagen remains stable in both pressure and tension sites of all three groups, compared with control side by the time consuming. 2. The change in soluble collagen showed the most highest level in tension site, lowest level in pressure site of $PGE_2$ treated group in 5th. experimental day. 3. The change in chondroitin sulfate showed the most highest level in pressure site, lowest level in tension site of $PGE_2$ treated group in 5th. experimental day. 4. In indomethacin treated group, the change of soluble collagen and chondroitin sulfate showed small range of variance compared with $PGE_2$ treated and normal group.

• Smart Structures and Systems
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• v.29 no.1
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• pp.167-179
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• 2022

This article develops a long-term condition assessment method for stay cables in cable stayed bridges using the monitored cable tension forces under operational condition. Based on the concept of influence surface, the matched cable tension ratio of two cables located at the same side (either in the upstream side or downstream side) is theoretically proven to be related to the condition of stay cables and independent of the positions of vehicles on the bridge. A sensor grouping scheme is designed to ensure that reliable damage detection result can be obtained even when sensor fault occurs in the neighbor of the damaged cable. Cable forces measured from an in-service cable-stayed bridge in China are used to demonstrate the accuracy and effectiveness of the proposed method. Damage detection results show that the proposed approach is sensitive to the rupture of wire damage in a specific cable and is robust to environmental effects, measurement noise, sensor fault and different traffic patterns. Using the damage sensitive feature in the proposed approach, the metrics such as accuracy, precision, recall and F1 score, which are used to evaluate the performance of damage detection, are 97.97%, 95.08%, 100% and 97.48%, respectively. These results indicate that the proposed approach can reliably detect the damage in stay cables. In addition, the proposed approach is efficient and promising with applications to the field monitoring of cables in cable-stayed bridges.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1836-1842
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• 1996

In this paper, static and fatigue bending strengths of CFRP(carbon fiber reinforced plastic laminates having impact damage(FOD) are evaluated. Composite laminates used for this experiment are CF/EPOXY and CF/PEEK orthotropy laminated plates, which have two-interfaces[${0^0}_4{90^0}_4}$]$_sym$. A steel ball launched by the air gun colides against CFRP laminates to generate impact damages. The damage growth during bending fatigue test is observed by the scanning acoustic microscope(SAM). When the impacted side is compressed, the residual fatigue bending strength of CF/PEEK specimen P is greater that that of CF/EPOXY SPECIMEN B. On the other hand, when the impacted side is in tension, the residual fatigue bending strength of CF/PEEK speicemen P is smaller than that of CF/EPOXY specimen B. In the case of impacted-side compression, fracture is proposed from the transverse crack generated near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-b delamination in the case of impacted-side tension.

• Steel and Composite Structures
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• v.32 no.4
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• pp.497-507
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• 2019

Exposed column base connections are used in low- to mid-rise steel moment resisting frames. This paper is to investigate the effect of the base plate thickness on the exposed column base connection strength, stiffness, and energy dissipation. Five specimens with different base plate thickness were numerically modelled using ABAQUS software. The numerical model is able to reproduce the key characteristics of the experimental response. Based on the numerical analysis, the critical base plate thickness to identify the base plate and anchor rod yield mechanism is proposed. For the connection with base plate yield mechanism, the resisting moment is carried by the flexural bending of the base plate. Yield lines in the base plate on the tension side and compression side are illustrated, respectively. This type of connection exhibits a relatively large energy dissipation. For the connection with anchor rod yield mechanism, the moment is resisted through a combination of bearing stresses of concrete foundation on the compression side and tensile forces in the anchor rods on the tension side. This type of connection exhibits self-centering behavior and shows higher initial stiffness and bending strength. In addition, the methods to predict the moment resistance of the connection with different yield mechanisms are presented. And the evaluated moment resistances agree well with the values obtained from the FEM model.