• Steel and Composite Structures
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• v.32 no.3
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• pp.337-346
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• 2019

The present paper tries to contribute fill the gap of application of the component method to tubular connections. For this purpose, one typical joint configuration in which just one component can be considered as active has been studied. These joints were selected as symmetrically loaded welded connections in which the beam width was the same as the column width. This focused the study on the component 'side walls of rectangular hollow sections (RHS) in tension/compression'. It should be one of the main components to be considered in welded unstiffened joints between I beams and RHS columns. Many experimental tests on double-sided I-beam-to-RHS-column joint with a width ratio 1 have been carried out by the authors and a finite element (FE) model was validated with their results. Then, some different analytical approaches for the component stiffness and strength have been assessed. Finally, the stiffness proposals have been compared with some FE simulations on I-beam-to-RHS-column joints. This work finally proposes the most adequate equations that were found for the stiffness and strength characterization of the component 'side walls of RHS in tension/compression' to be applied in a further unified global proposal for the application of the component method to RHS.

• Computers and Concrete
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• v.33 no.5
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• pp.519-533
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• 2024

Many materials including cementitious concrete-type materials undergo material property changes during high-rate loading. There is a wealth of research regarding this phenomenon for concrete in compression and tension. However, there is minimal knowledge about how mortar material used in concrete masonry unit (CMU) construction behaves in high-rate shear loading. A series of experiments was conducted to examine the bond strength of mortar bonded to CMU units under high-rate shear loading. A novel experimental setup using a shock tube and dynamic ram were used to load specially constructed shear triplets in a double lap shear configuration with no pre-compression. The Finite Element Method was leveraged in conjunction with data from the experimental investigation to establish if the shear bond between concrete masonry units and mortar exhibits any rate dependency. An increase in shear bond strength was observed when loaded at a high strain rate. This data indicates that the CMU-mortar bond exhibits a rate dependent strength change and illustrates the need for further study of the CMU-mortar interface characteristics at high strain rates.

• Archives of Reconstructive Microsurgery
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• v.21 no.2
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• pp.81-85
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• 2012

Purpose: Saturday night palsy is a transient form of nerve palsy that occurs after a prolonged period of direct pressure on the course of radial nerve by one's own or spouse's head. Although commonly encountered, there have been only few studies concerning its convalescence. The purpose of this study is to predict the prognosis of Saturday night palsy based on the causes, time to recovery and degree of recovery. Materials and Methods: Retrospective study of 20 patients who were diagnosed compression radial nerve palsy was performed. The average age was 36.7 years old and the mean follow-up period was 19.6 months. We investigated sleeping hours as an indirect measure of nerve compression time, recovery of wrist and finger extension, DASH score on the monthly based follow up. Results: The mean sleeping hours was 5.8 hours and all patients showed full recovery of wrist and fingers extension with the mean duration of symptom for 3.2 months. DASH score was an average 1.53 at the last follow up and we found no statistical significance between the time to recovery and the sleeping hours. Conclusion: Complete natural recovery can be expected in compression radial nerve palsy in this study without correlation with sleeping time. Accurate diagnosis is important in order to avoid unnecessary therapeutic intervention and further study should be accomplished for clarifying the related prognostic factors in larger scale of the cases.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.3
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• pp.265-276
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• 2007

The primary objective of this study is to investigate the effect of media on the performance of biofilters. Two types of experiments were carried out in this study. The first type of experiment used a biofilter with the media composed of three different packing materials of compost, peatmoss and GAC(granular activated carbon), whereas the second type used a biofilter with the media composed of compost only. It was found from the two experiments that the biofilter composed of compost, peatmoss and GAC showed better performance than the one composed of compost only with the higher toluene removal efficiency, lower pressure drop, and more uniform media moisture content. In particular, no appreciable media compression occurred for the biofilter composed of compost, peatmoss and GAC, whereas significant media compression took place in the biofilter composed of compost only. As suggested by the other researchers, it is likely that GAC may be responsible for the higher toluene removal efficiency in the case of the biofilter composed of mixed media especially for the early stage of biofiltration due to its adsorption capability of toluene of such high concentration as 300 ppm. It was also regarded that GAC may playa major role in maintaining lower media pressure drop in the case of the mixed media than the media with compost only because of its mechanical strength resisting to the compression. Nonetheless, further refined experiments may need to draw more accurate conclusion. The results of the additional test run using the same mixed media showed that the biofilter system using the mixed media can be consistently operated for more than 100 days very stably despite sudden change in operating conditions of temperature and flow rate.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.17 no.1
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• pp.15-23
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• 2011

Background: The objective of this study was to determine the effectiveness of the pelvic compression belt (PCB) on the thickness of the transversus abdominis (TrA) during active straight leg raising (ASLR). Methods: Thirty healthy subjects (10 men and 20 women) volunteered to participate in this study. The thickness of TrA was measured using a real-time ultrasonic diagnostic imaging system. Subjects were instructed to rest in a resting (hook-lying) position and to perform ASLR with and without the PCB. The PCB was positioned below the anterior superior iliac spine with stabilizing pressure from elastic bands. Results: In the resting position and during ASLR, the thickness of the TrA significantly differed between subjects with and without PCB (p<.05). In addition, there was a significant interaction between the measurement position and the presence or absence of PCB (p<.05). Conclusions: These findings suggest that the PCB may affect deep core muscles such as TrA during various activities. Further studies are required to generalize the results of the present study.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.421-428
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• 2007

This paper investigates the combustion and emission characteristics of a compression ignition engine fueled with neat and blended Shell's gas-to-liquid (GTL) fuel, which was derived from natural gas through the Fischer-Tropsch process. The experiments were conducted in a 6-cylinder DI diesel engine with pump timing settings of $6^{\circ},\;9^{\circ}\;and\;12^{\circ}$crank angle before TDC over ECE R49 and US 13-mode cycles separately and compared to a conventional diesel fuel. The results show that GTL exhibited almost the same power and torque output, improved fuel economy and effective thermal efficiency. It was found that GTL displayed lower peak in-cylinder combustion pressure and maximum heat release rate (HRR), the timings of the peak pressure and the maximum HRR were generally delayed, and the combustion durations were almost equivalent for diesel and GTL under the same speed-load condition. The results also indicate that, compared to diesel fuel, GTL blends showed a trend forward decreasing four regulated emissions simultaneously and a higher GTL fraction in blends contributing to further reductions in the emissions. In particular and on average, neat GTL significantly reduced HC, CO, NOx and PM by 16.4%, 17.8%, 18.3% and 32.4%, respectively, for all cases.

• Journal of Korean Neurosurgical Society
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• v.52 no.4
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• pp.339-345
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• 2012

Objective : The purpose of this study was to investigate the patterns and the risk factors of newly developed vertebral compression fractures (VCFs) after percutaneous vertebroplasty (PVP). Methods : We performed a retrospective review of the 244 patients treated with PVP from September 2006 to February 2011. Among these patients, we selected 49 patients with newly developed VCFs following PVP as the new VCFs group, and the remaining 195 patients as the no VCFs group. The new VCFs group was further divided into 2 groups : an adjacent fractures group and a nonadjacent fractures group. The following data were collected from the groups : age, gender, body weight/height, body mass index (BMI), bone mineral density (BMD) score of the spine and femur, level of initial fracture, restoration rate of anterior/middle vertebral height, and intradiscal cement leakage, volume of polymethylmethacrylate (PMMA). Results : Age, gender, mean body height/weight, mean BMI and volume of PMMA of each of the group are not statistically significantly associated with fractures. In comparison between the new VCFs group and the no VCFs group, lower BMD, intradiscal cement leakage and anterior vertebral height restoration were the significant predictive factors of the fracture. In addition, new VCFs occurrence at the adjacent spines was statistically significant, when the initial fracture levels were confined to the thoracolumbar junction, among the subgroups of new VCFs. Conclusion : Lower spinal BMD, the greater anterior vertebral height restoration rate and intradiscal cement leakage were confirmed as risk factors for newly formed VCFs after PVP.

• Journal of Korean Neurosurgical Society
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• v.42 no.4
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• pp.271-275
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• 2007

Objective : Although a significant correction of local kyphosis has been reported previously, only a few studies have investigated whether this correction leads to an improved overall sagittal alignment. The study objective was to determine whether an improvement in the local kyphotic angle improves the overall sagittal alignment. We examined and compared the effects of thoracic and lumbar level kyphoplasty procedures on local versus overall sagittal alignment of the spine. Methods : Thirty-eight patients with osteoporotic vertebral compression fractures who showed poor response to conventional, palliative medical therapy underwent single-level kyphoplasty. The pertinent clinical data of these patients, from June 2006 to November 2006, were reviewed retrospectively. We measured preoperative and postoperative vertebral body heights, which were classified as anterior, middle, or posterior fractured vertebral body heights. Furthermore, the local and overall sagittal angles after polymethylmethacrylate deposition were measured. Results : More height was gained at the thoracic level, and the middle vertebral height regained the most. A significant local kyphosis correction was observed at the fractured level, and the correction at larger spanning segments decreased with the distance from the fractured level. Conclusion : The inflatable balloon kyphoplasty procedure was the most effective in regaining the height of the thoracic fractured vertebra in the middle vertebral body. The kyphosis correction by kyphoplasty was mainly achieved in the fractured vertebral body. Sagittal angular correction decreased with an increase in the distance from the fractured vertebra. No significant improvement was observed in the overall sagittal alignment after kyphoplasty. Further studies in a larger population are required to clarify this issue.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.858-869
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• 2014

Most of the aerospace propulsion is based on the Brayton cycle, in which the combustion is held through the constant pressure process, but further improvement of performance by increasing compression ratio is challenged by mechanical limits. Detonation propulsions, regarded promising for high-speed propulsion for a lase decade, is more rigorously studied in these days as a game-changer for the improvement of thermodynamic efficiency of propulsion and power generation systems. Since, the additional compression by the strong shock of the detonation wave is considered increasing thermodynamics efficiency that is hardly achievable by the conventional compression systems. Present paper will give an introduction the latest technical trends on the Pulse Detonation Engines(PDEs) and the activities on the Pressure Gain Combustion (PGC) based on Constant Volume Combustion (CVC).

• Journal of Korean Academy of Nursing Administration
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• v.23 no.1
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• pp.63-75
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• 2017

Purpose: This study was conducted to adapt the standardized evidence-based nursing protocol using the IPC (intermittent pneumatic compression) intervention to prevent venous thromboembolism in surgical patients. Further, an investigation was done to measure knowledge on prevention of venous thromboembolism, surrogate incidence of venous thromboembolism and to assess IPC compliance in the study patients compared with those in surgical patients who underwent IPC intervention due to previous clinical experience. Methods: An analysis was done of the nine modules suggested by National Evidence-based Healthcare Collaborating Agency (NECA) in the adaptation manual of the clinical practice guideline for protocol adaptation. A nonequivalent control group post test design as a quasi-experiment was used to verify the effect of the IPC protocol. Results: There was a significant difference in knowledge of prevention of venous thromboembolism, IPC application time after intervention and the number of IPC applications between the experimental group (n=50) using the IPC nursing protocol and the control group (n=49). However, the symptoms of deep vein thrombosis and pulmonary thromboembolism were not observed in either the experimental group or the control group after the intervention. Conclusion: Results confirm that the standardized IPC nursing protocol provides effective intervention to prevent venous thromboembolism in surgical patients.