• Earthquakes and Structures
• /
• v.22 no.1
• /
• pp.1-13
• /
• 2022

When a building suffers damages under moderate to severe loading condition, its physical properties such as damping and stiffness parameters will change. There are different practical methods besides various numerical procedures that have successfully detected a range of these changes. Almost all the previous proposed methods used to work with translational components of mode shapes, probably because extracting these components is more common in vibrational tests. This study set out to investigate the influence of using both rotational and translational components of mode shapes, in detecting damages in 3-D steel structures elements. Three different sets of measured components of mode shapes are examined: translational, rotational, and also rotational/translational components in all joints. In order to validate our assumptions two different steel frames with three damage scenarios are considered. An iterative model updating program is developed in the MATLAB software that uses the OpenSees as its finite element analysis engine. Extensive analysis shows that employing rotational components results in more precise prediction of damage location and its intensity. Since measuring rotational components of mode shapes still is not very convenient, modal dynamic expansion technique is applied to generate rotational components from measured translational ones. The findings indicated that the developed model updating program is really efficient in damage detection even with generated data and considering noise effects. Moreover, methods which use rotational components of mode shapes can predict damage's location and its intensity more precisely than the ones which only work with translational data.

• Physical Therapy Korea
• /
• v.29 no.1
• /
• pp.1-10
• /
• 2022

Background: Neck pain is a major health problem in developed countries and has a lifetime prevalence of 50%. Major problems include a reduced cervical range of motion, muscle stiffness, dysfunction, postural changes, and decrease in psychosocial level. Objects: This study aimed to investigate the effects of applying the upper trapezius inhibition dynamic taping to patients with chronic neck pain on their neck pain, functional level, cervical range of motion, psychosocial level, and neck posture. Methods: The study design was a randomized controlled trial. A total of 40 patients with neck pain participated in this study and were randomly assigned to a Dynamic Taping group (n = 20) or Sham Taping group (n = 20). In both groups, basic intervention cervical pain control therapy and shoulder stabilization exercise program were performed. In addition, dynamic taping and sham taping were applied to participants in the Dynamic Taping and Sham Taping groups to inhibit the trapezius muscle, respectively. All interventions were performed three times a week and a total of 12 times for 4 weeks, and the participants' neck pain, functional impairment level, cervical range of motion, psychosocial level, and neck posture were measured and compared before and after the intervention. Results: Both groups showed significant differences in neck pain, functional level, cervical range of motion, psychosocial level, and neck postural before and after the intervention (p < 0.05). Moreover, there were significant differences between the two groups regarding the functional level and neck posture (p < 0.05). Conclusion: Inhibition dynamic taping of the upper trapezius muscle suppression is an effective method with clinical significance in reducing pain in individuals with chronic neck pain and improving the functional level, cervical range of motion, psychosocial level, and neck posture.

• Geomechanics and Engineering
• /
• v.29 no.1
• /
• pp.25-40
• /
• 2022

In this study, 3D coupled-consolidation numerical parametric study was conducted to predict the deformation mechanism of a 20 storey building sitting on (4×4) piled raft (with length of piles, L_p=30 m) to adjacent 6 m diameter (D) tunnelling in stiff clay. The influences of different tunnel locations relative to piles (i.e., z_t/L_p) were investigated in this parametric study. In first case, the tunnel was excavated near the pile shafts with depth of tunnel axis (z_t) of 9 m (i.e., z_t/L_p). In second and third cases, tunnels were driven at z_t of 30 m and 42 m (i.e., z_t/L_p = 1.0 and 1.4), respectively. An advanced hypoplastic clay model (which is capable of taking small-strain stiffness in account) was adopted to capture soil behaviour. The computed results revealed that tunnelling activity adjacent to a building resting on piled raft caused significant settlement, differential settlement, lateral deflection, angular distortion in the building. In addition, substantial bending moment, shear forces and changes in axial load distribution along pile length were induced. The findings from the parametric study revealed that the building and pile responses significantly influenced by tunnel location relative to pile.

• Journal of the Semiconductor & Display Technology
• /
• v.21 no.1
• /
• pp.148-154
• /
• 2022

As the 4th industrial age approaches, the demand for semiconductors is increasing enough to be used in all electronic devices. At the same time, semiconductor technology is also developing day by day, leading to ultraprecision and low power consumption. Semiconductors that keep getting smaller generate heat because the energy density increases, and the generated heat changes the shape of the semiconductor package, so it is important to manage. The temperature change is not only self-heating of the semiconductor package, but also heat generated by external damage. If the package is deformed, it is necessary to manage it because functional problems and performance degradation such as damage occur. The package burn in test in the post-process of semiconductor production is a process that tests the durability and function of the package in a high-temperature environment, and heat dissipation performance can be evaluated. In this paper, we intend to review a new material formulation that can improve the performance of the adapter, which is one of the parts of the test socket used in the burn-in test. It was confirmed what characteristics the basic base showed when polyamide, a high-molecular material, and alumina, which had high thermal conductivity, were mixed for each magnification. In this study, functional evaluation was also carried out by injecting an adapter, a part of the test socket, at the same time as the specimen was manufactured. Verification of stiffness such as tensile strength and flexural strength by mixing ratio, performance evaluation such as thermal conductivity, and manufacturing of a dummy device also confirmed warpage. As a result, it was confirmed that the thermal stability was excellent. Through this study, it is thought that it can be used as basic data for the development of materials for burn-in sockets in the future.

• Geomechanics and Engineering
• /
• v.33 no.2
• /
• pp.221-230
• /
• 2023

The liquefaction of soil occurs when a soil loses strength and stiffness because of applied stress, such as an earthquake or other changes in stress conditions that result in a loss of cohesion. Hence, a method for improving the strength of liquefiable soil needs to be developed. Many techniques have been presented for their possible applications to mitigate liquefiable soil. Recently, alternative methods using biopolymers (such as xanthan gum, guar gum, and gellan gum), nontraditional additives, have been introduced to stabilize fine-grained soils. However, no studies have been done on the use of carrageenan as a biopolymer for soil improvement. Due to of its rheological and chemical structure, carrageenan may have the potential for use as a biopolymer for soil improvement. This research aims to investigate the effect of adding carrageenan on the soil strength of treated liquefiable soil. The biopolymers used for comparison are carrageenan (as a novel biopolymer), xanthan gum, and guar gum. Then, sand samples were made in cylindrical molds (5 cm × 10 cm) by the dry mixing method. The amount of each biopolymer was 1%, 3%, and 5% of the total sample volume with a moisture content of 20%, and the samples were cured for seven days. In terms of observing the effect of temperature on the carrageenan-treated soil, several samples were prepared with dry sand that was heated in an oven at various temperatures (i.e., 20℃ to 75℃) before mixing. The samples were tested with the direct shear test, UCS test, and SEM test. It can increase the cohesion value of liquefiable soil by 22% to 60% compared to untreated soil. It also made the characteristics of the liquefiable increase by 60% to 92% from very loose sandy soil (i.e., ϕ=29°) to very dense sandy soil. Carrageenan was also shown to have a significant effect on the compressive strength and to exceed the liquefaction limit. Based on the results, carrageenan was found to have the potential for use as an alternative biopolymer.

• Journal of Oral Medicine and Pain
• /
• v.48 no.1
• /
• pp.31-36
• /
• 2023

This report presents the case of a 14-year-old male with rheumatoid arthritis (RA) in both temporomandibular joints (TMJs), in whom a bone scan and laboratory tests were used to confirm the diagnosis. The patient visited the Department of Orofacial Pain and Oral Medicine at the affiliation hospital with a complaint of a 1-year history of bilateral TMJ pain and sound. Clinical examination revealed bilateral TMJ and masseter muscle pain during mouth opening and palpation. Radiological examination revealed no significant morphological changes in either TMJ. The patient was prescribed medications at the first visit to address the pain, inflammation, and stiffness. A bone scan and laboratory tests were planned/scheduled for differential diagnosis between simple arthralgia and osteoarthritis. The bone scan revealed increased radiotracer uptake in both TMJs. The laboratory tests revealed a RA factor of 82.4 IU/mL, which is more than four times the normal range. The final diagnoses were bilateral TMJ early rheumatoid arthritis (ERA) and juvenile idiopathic arthritis. We created a stabilization splint and referred the patient to the Department of Rheumatology for further evaluation of the ERA. After fitting of the stabilization splint and giving instructions regarding its use, the patient has been receiving monthly follow-up checks for symptoms and undergoes follow-up blood tests every 3 months. About 14 months after the initial visit, the pain had significantly decreased from a Visual Analog Scale score of 5 to 1, and the RA factor decreased to 66.6 IU/mL. A regular follow-up check will continue until the end of growth.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6D
• /
• pp.895-904
• /
• 2008

CWR (Continuous Welded Rail) may be broken when a temperature drop below the neutral temperature changes in axial force, causing tensile fracture and rail gap, in winter. Rail-breaks may lead to the damage of the rail and wheel by dynamic load, and the reduction of running safety if not detected before the passage of a train. In this study, the track and train coupled model with open gap for dynamic interaction analysis, is proposed. Linear track and train systems is coupled by the nonlinear Herzian contact spring and the complete system matrices of total track-train system is constructed. And the interaction phenomenon considering open gap, was defined by assigning the irregularity functions between the two sides of a gap. Time history analysis, which have an iteration scheme such as $Newmark-{\beta}$ method based on Modified Newton-Raphson methods, was performed to solve the nonlinear equation. Finally, numerical studies are performed to assess the effect of various parameters of system, apply to various speeds, open gap size and the support stiffness of rail.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.1
• /
• pp.85-95
• /
• 2009

In urban areas, blast excavation adjacent to tunnels is carried out frequently. It is generally required to secure static and dynamic stability of nearby tunnel structures for any such activities. Although there is some national guidelines for static safety, there is little guides to risk zoning controling the dynamic behavior of the underground structures. In this study, impacts on the blast-induced vibration are investigated using numerical study. An attempt to define the restricted area of blast adjacent to subway tunnels was also made. Particular concerns were given to tunnel depth and ground types. By carrying out the parametric study on depth and ground patterns, the envelope of blast distance of which dynamic response on the lining is controlled under 1 cm/sec, is established. It is shown that the increase in depth has increased the required safety distance slightly until the distance of 3.5 times of the tunnel diameter. Despite small changes in safety distance, it can be generally said that the effects of depth and stiffness of the ground is not significant in controlling the particle velocity of the tunnel linings.

• PNF and Movement
• /
• v.22 no.1
• /
• pp.71-80
• /
• 2024

Purpose: The purpose of this study is to compare the effects of proprioceptive neuromuscular facilitation (PNF) stretching, based on ballistic stretching and the contract-relax technique, on hip joint flexibility and muscle tone in adults with shortened rectus femoris muscles. Methods: The study involved 40 adults with shortened rectus femoris muscles, identified using the modified Thomas test. Participants were randomly divided into two groups: PNF stretching, employing the contract-relax technique, and ballistic stretching. Measurements included muscle tension, hip joint range of motion, and muscle characteristics. The rectus femoris muscle shortening effect was confirmed by the modified Thomas test, while the flexibility effect was assessed through hip joint motion range. The muscle tension effect was determined using Myoton-PRO. Results: Both stretching methods resulted in significant improvements in modified Thomas test angles and frequency, with the PNF stretching group showing notably greater changes. However, neither stretching method significantly affected decrement or stiffness measurements. These findings suggest that PNF stretching may be more effective for certain outcomes compared to ballistic stretching. Conclusion: In summary, both stretching methods positively influenced flexibility and muscle tension, with PNF stretching showing a greater impact. These findings highlight the importance of selecting the appropriate stretching technique for achieving functional improvements in muscles, which could serve as valuable indicators for preventing and treating muscle injuries in both sports and daily activities.

• Korean Circulation Journal
• /
• v.53 no.6
• /
• pp.406-417
• /
• 2023

Background and Objectives: Pathophysiological changes of right ventricle (RV) after repair of tetralogy of Fallot (TOF) are coupled with a highly compliant low-pressure pulmonary artery (PA) system. This study aimed to determine whether pulmonary vascular function was associated with RV parameters and exercise capacity, and its impact on RV remodeling after pulmonary valve replacement. Methods: In a total of 48 patients over 18 years of age with repaired TOF, pulmonary arterial elastance (Ea), RV volume data, and RV-PA coupling ratio were calculated and analyzed in relation to exercise capacity. Results: Patients with a low Ea showed a more severe pulmonary regurgitation volume index, greater RV end-diastolic volume index, and greater effective RV stroke volume (p=0.039, p=0.013, and p=0.011, respectively). Patients with a high Ea had lower exercise capacity than those with a low Ea (peak oxygen consumption [peak VO₂] rate: 25.8±7.7 vs. 34.3±5.5 mL/kg/min, respectively, p=0.003), while peak VO₂ was inversely correlated with Ea and mean PA pressure (p=0.004 and p=0.004, respectively). In the univariate analysis, a higher preoperative RV end-diastolic volume index and RV end-systolic volume index, left ventricular end-systolic volume index, and higher RV-PA coupling ratio were risk factors for suboptimal outcomes. Preoperative RV volume and RV-PA coupling ratio reflecting the adaptive PA system response are important factors in optimal postoperative results. Conclusions: We found that PA vascular dysfunction, presenting as elevated Ea in TOF, may contribute to exercise intolerance. However, Ea was inversely correlated with pulmonary regurgitation (PR) severity, which may prevent PR, RV dilatation, and left ventricular dilatation in the absence of significant pulmonary stenosis.