• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.36 no.5
• /
• pp.185-191
• /
• 2014

Purpose: Although there have been several studies of reduced airway space after mandibular setback surgery using the sagittal split ramus osteotomy technique, research on the risk factors for changes of the airway space is lacking. Therefore, this study was performed to examine airway changes and the position of the hyoid bone after orthognathic surgery, and to assess possible risk factors. Methods: In this retrospective study, 50 patients who underwent posterior displacement of the mandible by the bilateral sagittal split ramus osteotomy technique were included. Changes of the position of the hyoid bone and the airway space were analyzed over various follow-up periods, using cephalometric radiography taken preoperatively, immediately after surgery, eight weeks after surgery, six months after surgery, and one year after surgery. To identify risk factors, multiple regression analysis of age, gender, body mass index (BMI), posterior mandibular movement, and the presence of genioplasty was performed. Results: Inferor and posterior movement of the hyoid bone was observed postoperatively, but subsequent observations showed regression towards the anterosuperior aspect. The airway space also significantly decreased after surgery (P<0.05), and increased slightly up until six months after surgery. The airway space significantly decreased (${\beta}=0.47$, P<0.01) as the amount of mandibular setback increased. However, age, sex, BMI, and presence of genioplasty were not associated with airway reduction. Conclusion: The amount of mandibular set back was significantly associated with postoperative reduction of airway space. It is necessary to establish a treatment plan considering this factor.

• Smart Structures and Systems
• /
• v.20 no.3
• /
• pp.369-383
• /
• 2017

In this work, the effects of moisture and temperature on free vibration characteristics of functionally graded (FG) nanobeams resting on elastic foundation is studied by proposing a novel simple trigonometric shear deformation theory. The main advantage of this theory is that, in addition to including the shear deformation influence, the displacement field is modeled with only 2 unknowns as the case of the classical beam theory (CBT) and which is even less than the Timoshenko beam theory (TBT). Three types of environmental condition namely uniform, linear, and sinusoidal hygrothermal loading are studied. Material properties of FG beams are assumed to vary according to a power law distribution of the volume fraction of the constituents. Equations of motion are derived from Hamilton's principle. Numerical examples are presented to show the validity and accuracy of present shear deformation theories. The effects of hygro-thermal environments, power law index, nonlocality and elastic foundation on the free vibration responses of FG beams under hygro-thermal effect are investigated.

• Geomechanics and Engineering
• /
• v.7 no.5
• /
• pp.477-493
• /
• 2014

This study examines the behaviour of single micropiles subjected to axial tension or compression load in collapsible loess under in-situ moisture content and saturated condition. Five tension loading tests and five compression loading tests on single micropiles were carried out at a typical loess site of the Loess Plateau in Northwest China. A series of laboratory tests, including grain size distribution, specific gravity, moisture content, Atterberg limits, density, granular components, shear strength, and collapse index, were carried out during the micropile loading tests to determine the values of soil parameters. The loess at the test site poses a severe collapse risk upon wetting. The tension or compression load-displacement curves of the micropiles in loess, under in-situ moisture content or saturated condition, can generally be simplified into three distinct regions: an initial linear, a curvilinear transition, and a final linear region, and the bearing capacity or failure load can be interpreted by the L1-L2 method as done in other studies. Micropiles in loess should be considered as frictional pile foundations though the tip resistances are about 10%-15% of the applied loads. Both the tension and compression capacities increase linearly with the ratio of the pile length to the shaft diameter, L/d. For micropiles in loess under in-situ moisture content, the interpreted failure loads or capacities under tension are 66%-87% of those under compression. However, the prewetting of the loess can lead to the reductions of 50% in the tensile bearing capacity and 70% in the compressive bearing capacity.

• The Journal of Korean Physical Therapy
• /
• v.27 no.5
• /
• pp.332-338
• /
• 2015

Purpose: The purpose of this study was to examine the effect of postural control and locomotion on improvement of two point discrimination (TPD), stereognosis (ST) through somatosensory training (SST) on the upper limb (UL). Methods: The subjects were 20 hemiplegia patients who have problems with unilateral neglect after stroke. The patients were divided into two groups, the experimental group (EG) and the control group (CG). In the EG, SST for TPD, ST was performed 18 times, three times a week for six weeks, together with physical therapy (PT) and occupational therapy (OT). In the CG conventional PT and OT without SST was performed for six weeks. Several assessment tools were used in comparison of groups; two point discrimination test (TPDT) on forearm (F), thenar (T), hypothenar (TH), thumb tip (TH-T), index finger tip (IN-T), stereognosis test (ST), postural assessment scale for stroke (PASS), and clinical test of sensory interaction on balance (CTSIB) and timed up and go test (TUG). Results: In the CG, conventional PT and OT resulted in statistically improved TPDT (F), ST, PASS, and TUG. In the EG, SST resulted in statistically improved TPDT (F, T, HT, TH-T, IN-T), ST, PASS, and TUG. TPDT-T, ST, and CTSIB with length of displacement with eye open (LDEO) also showed significant improvement between the groups. Conclusion: In both groups TPDT ST, PASS and TUG, and SST had effects on the UL and TPDT, ST and static postural control had greater effects compared with the PG. Therefore, we could assume that TPD and ST are very important in performing human activities including postural control and locomotion.

• Physical Therapy Korea
• /
• v.27 no.2
• /
• pp.126-132
• /
• 2020

Background: Augmented somatosensory feedback stimulates the mechanoreceptor to deliver information on bodily position, improving the postural control. The various types of such feedback include ankle-foot orthoses (AFOs) and vibration. The optimal feedback to mitigate postural sway remains unclear, as does the effect of augmented somatosensory feedback on muscle co-contraction. Objects: We compared postural sway and ankle muscle co-contraction without feedback (control) and with either of two forms of somatosensory feedback (AFOs and vibration). Methods: We recruited 15 healthy subjects and tested them under three feedback conditions (control, AFOs, vibration) with two sensory conditions (eyes open, or eyes closed and the head tilted back), in random order. Postural sway was measured using a force platform; the mean sway area of the 95% confidence ellipse (AREA) and the mean velocity of the center-of-pressure displacement (VEL) were assessed. Co-contraction of the tibialis anterior and gastrocnemius muscles was measured using electromyography and converted into a co-contraction index (CI). Results: We found significant main effects of the three feedback states on postural sway (AREA, VEL) and the CI. The two sensory conditions exerted significant main effects on postural sway (AREA and VEL). AFOs reduced postural sway to a level significantly lower than that of the control (p = 0.014, p < 0.001) or that afforded by vibration (p = 0.024, p < 0.001). In terms of CI amelioration, the AFOs condition was significantly better than the control (p = 0.004). Vibration did not significantly improve either postural sway or the CI compared to the control condition. There was no significant interaction effect between the three feedback conditions and the two sensory conditions. Conclusion: Lower-extremity devices such as AFOs enhance somatosensory perception, improving postural control and decreasing the CI during static standing.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.38
• /
• pp.32.1-32.6
• /
• 2016

Background: This study aimed to analyze and describe the morbidity and mortality associated with tracheostomy in patients with oral cancer and to identify the risk factors associated with tracheostomy complications. Methods: We performed a retrospective chart review of patients who underwent tracheostomy during a major oral cancer resection between March 2001 and January 2016 at the National Cancer Center, Korea. Overall, we included 51 patients who underwent tracheostomy after oral cancer surgery. We assessed the morbidity and mortality of tracheostomy and determined the risks associated with tracheostomy complications. Results: Twenty-two tracheostomy-related complications occurred in 51 patients. The morbidity and mortality rates were 35.2 % (n = 18) and 0 % (n = 0), respectively. Tracheostomy-related complications were tracheitis (n = 4), obstructed tracheostomy (n = 9), displaced tracheostomy (n = 5), air leakage (n = 1), stomal dehiscence (n = 1), and decannulation failure (n = 2). Most complications (19/22) occurred during the early postoperative period. Considering the risk factors for tracheostomy complications, the type of tube used was associated with the occurrence of tracheitis (p < 0.05). Additionally, body mass index and smoking status were associated with tube displacement (p < 0.05). However, no risk factors were significantly associated with obstructed tracheostomy. Conclusions: Patients with risk factors for tracheostomy complications should be carefully observed during the early postoperative period by well-trained medical staff.

• The korean journal of orthodontics
• /
• v.43 no.4
• /
• pp.193-200
• /
• 2013

Objective: To evaluate the psychosocial impact of malocclusion, determine its relationship with the severity of malocclusion, and assess the influence of gender and social class on this relationship in adolescents. Methods: A random sample of 627 Spanish adolescents aged 12 - 15 years underwent intraoral examinations by 3 calibrated examiners (intraexaminer and interexaminer kappa > 0.85) at their schools. Psychosocial impact was measured through a self-rated Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ). The severity of malocclusion was measured by the Index of Orthodontic Treatment Need (IOTN). Gender and social class were also recorded. Results: The total PIDAQ score and those of its 4 subscales, social impact, psychological impact, aesthetic concern, and dental self-confidence, presented significant differences ($p{\leq}0.05$ by analysis of variance) and linear relationships with the IOTN grades ($p{\leq}0.05$ by linear regression). Stepwise linear regression models showed that the IOTN dental health component was a predictive variable of the total and subscale PIDAQ scores. Neither gender nor social class was an independent predictive variable of this relationship, except the linear model for psychological impact, where gender was a predictive variable. The occlusal conditions responsible for higher PIDAQ scores were increased overjet, impeded eruption, tooth displacement, and increased overbite. Conclusions: Malocclusion has a psychological impact in adolescents and this impact increases with the severity of malocclusion. Social class may not influence this association, but the psychological impact seems to be greater among girls.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.10a
• /
• pp.334-408
• /
• 2006

In Hong Kong, large-diameter (${\ge}600mm$) bored piles and large-section excavated rectangular barrettes are commonly used to support tall buildings to resist both vertical and horizontal loads. These piles and barrettes penetrate through and may found in saprolitic soils and decomposed rocks. Generally, the design of these large bored piles and barrettes involves considerable amount of uncertainty and design parameters must usually be verified by field tests. In this paper, over 50 full-scale load tests on large-diameter bored piles and over 15 large-section of rectangular barrettes in Hong Kong are reviewed and interpreted critically, in particular the degree of mobilisation of side shear resistance using a mobilization rating (MR) factor and a displacement index (DI) for floating bored piles and barrettes and rock-socketed piles, respectively. The author was heavily involved with many of these load tests. The diameter of the bored piles tested ranges from 0.6m to 1.8m and the depth varies from 12m to 75m. Sizes of barrettes critically reviewed include $2.2m{\times}0.6m,\;2.2m{\times}0.8m,\;2.8m{\times}0.8m\;and\;2.8m{\times}1.0m$ (on plan) and the depth varies from 36m and 63m. Based on these field tests, a new failure load criterion for large-diameter bored piles and barrettes is developed and proposed. The side shear resistance of the bored piles and barrettes is quantitatively analyzed with respect to local displacements, standard penetration tests, unconfined compressive strength (UCS) for rock sockets and using the effective stress principle. In addition, the effects of construction including post-grouting, construction time, side scraping and excavation tools on side shear resistance are investigated and reported.

• The Korean Journal of Pain
• /
• v.31 no.2
• /
• pp.109-115
• /
• 2018

Background: Patients with lumbar disc herniation are treated with physiotherapy/medication and some with surgery. However, even after technically successful surgery some develop a failed back syndrome with persistent pain. Our aim was to evaluate the efficacy of epiduroscopy in patients who suffer chronic low back pain and/or radicular pain with or without surgery and the gender difference in outcome. Methods: A total of 88 patients were included with a mean age of 52 years (27-82), 54 women and 34 men. 66 of them were operated previously and 22 were non-operated. They all had persistent chronic back pain and radicular pain despite of medication and physical rehabilitation. Visual Analog Scale (VAS) for pain and Oswestry Disability Index (ODI) were evaluated preoperatively, after one month, six months and one-year after the epiduroscopy. Results: All patients, and also the subgroups (gender and operated/non-operated) improved significantly in pain (VAS) and disability (ODI) at one month. A significant improvement was also seen at one year. No differences were found between men and woman at the different follow-up times. A slight worsening in VAS and ODI was noticed over time except for the non-operated group. Conclusions: Epiduroscopy helps to improve the back and leg pain due to lumbar disc herniation in the early stage. At one year an improvement still exists, and the non-operated group seems to benefit most of the procedure.

• Structural Engineering and Mechanics
• /
• v.72 no.5
• /
• pp.631-642
• /
• 2019

The objective of the present study is to examine the flexural behavior of two-span post-tensioned lightweight aggregate concrete (LWAC) beams using unbonded tendons and the reliability of the design provisions of ACI 318-14 for such beams. The parameters investigated were the effective prestress and loading type, including the symmetrical top one-point, two third-point, and analogous uniform loading systems. The unbonded prestressing three-wire strands were arranged with a harped profile of variable eccentricity. The total length of the beam, measured between both strand anchorages, was 11000 mm. The test results were compared with those compiled from simply supported LWAC one-way members, wherever possible. The ultimate load capacity of the present beam specimens was evaluated by the collapse mechanism of the plasticity theorem and the nominal section moment strength calculated following the provision of the ACI 318-14. The test results showed that the two-span post-tensioned LWAC beams had lower stress increase (Δf_ps) in the unbonded tendons than the simply supported LWAC beams with a similar reinforcement index. The effect of the loading type on Δf_ps and displacement ductility was less significant for two-span beams than for the comparable simply supported beams. The design equations for Δf_ps and Δf_ps proposed by ACI 318-14 and Harajli are conservative for the present two-span post-tensioned LWAC beams, although the safety decreases for the two-span beam, compared to the ratios between experiments and predictions obtained from simply supported beams.