• Journal of Korean Society for Quality Management
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• v.47 no.3
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• pp.437-451
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• 2019

Purpose: The purpose of this study is to improve the quality of the PGM system by improving the structure and production process of slip-ring rotary joint for radar. Methods: The improvement measures for each cause are established through failure analysis of broken items. Specifically, changing in the housing to improve the heating system. Changing the transportation method to prevent damage to equipment during transport. Changing work process of the attenuator ring to prevent damage. etc. Results: The results of this study are as follows; improving the heating system reduces heat generated by the attenuator by about 7 degrees and obtain additional temperature margins. Reduction of defect rate because of adding X-band rotary joint run-out measurement test, ESS of slip-ring rotary joint and Transportation improvement(reinforced flight boxes, tube protection, etc). Getting stable VSWR values by improving work process of attenuator overheating due to a bad bonding process. Conclusion: Through this study, improvements were made to slip-ring rotary joint that failed repeatedly for various reasons. As a result of the application of the improvements, the same fault does not occur until now, so we can see that the quality of PGM has improved.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.3095-3105
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• 2022

Solid Microencapsulated Fuel (SMF) is a type of solid fuel rod design that disperses TRISO coated fuel particles directly into a kind of matrix. SMF is expected to provide improved performance because of the elimination of cladding tube and associated failure mechanisms. This study focused on the neutronics and some of the fuel cycle characteristics of SMF by using OpenMC. Two kinds of SMFs have been designed and evaluated - fuel particles dispersed into a silicon carbide matrix and fuel particles dispersed into a zirconium matrix. A 7×7 fuel assembly with increased rod diameter transformed from the standard NHR200-II 9×9 array was also introduced to increase the heavy metal inventory. A preliminary study of two kinds of burnable poisons (Erbia & Gadolinia) in two forms (BISO and QUADRISO particles) was also included. This study found that SMF requires about 12% enriched UN TRISO particles to match the cycle length of standard fuel when loaded in NHR200-II, which is about 7% for SMF with increased rod diameter. Feedback coefficients are less negative through the life of SMF than the reference. And it is estimated that the average center temperature of fuel kernel at fuel rod centerline is about 60 K below that of reference in this paper.

• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.173-189
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• 2022

This study presents an experimental and numerically study about the effects of fiber reinforcement ratio on the behavior of concrete-filled steel tubes (CFST) under dynamic impact loading. In literature have examined the behavior of GFRP and FRP wrapped strengthened CFST elements impact loads. However, since the direction of potential impact force isn't too exact, there is always the probability of not being matched the impact force of the area where the reinforced. Therefore, instead of the fiber textile wrapping method which strengthens only a particular area of CFST element, we used fiber-added concrete-filled elements which allow strengthening the whole element. Thus, the effect of fiber-addition in concrete on the behavior of CFST elements under impact loads was examined. To do so, six simply supported CFST beams were constructed with none fiber, 2% fiber and 10% fiber reinforcement ratio on the concrete part of the CFST beam. CFST beams were examined under two different impact loads (75 kg and 225 kg). The impactors hit the beam from a 2000 mm free fall during the experimental study. Numerical models of the specimens were created using ABAQUS finite element software and validated with experimental data. The obtained results such as; mid-span displacement, acceleration, failure modes and energies from experimental and numerical studies were compared and discussed. Furthermore, the Von Misses stress distribution of the CFST beams with different ratio of fiber reinforcements were investigated numerically. To sum up, there is an optimum amount limit of the fiber reinforcement on CFST beams. Up to this limit, the fiber reinforcement increases the structural performances of the beam, beyond that limit the fiber reinforcement decreases the performances of the CFST beam under transverse impact loadings.

• Structural Engineering and Mechanics
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• v.81 no.6
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• pp.715-728
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• 2022

A new type of buckling-restrained braces (BRBs) with a longitudinally profiled steel plate working as the core (LPBRB) is proposed and experimentally investigated. Different from conventional BRBs with a constant thickness core, both stiffness and strength of the longitudinally profiled steel core along its longitudinal direction can change through itself variable thickness, thus the construction of LPBRB saves material and reduces the processing cost. Four full-scale component tests were conducted under quasi-static cyclic loading to evaluate the seismic performance of LPBRB. Three stiffening methods were used to improve the fatigue performance of LPBRBs, which were bolt-assembled T-shaped stiffening ribs, partly-welded stiffening ribs and stiffening segment without rib. The experimental results showed LPBRB specimens displayed stable hysteretic behavior and satisfactory seismic property. There was no instability or rupture until the axial ductility ratio achieved 11.0. Failure modes included the out-of-plane buckling of the stiffening part outside the restraining member and core plate fatigue fracture around the longitudinally profiled segment. The effect of the stiffening methods on the fatigue performance is discussed. The critical buckling load of longitudinally profiled segment is derived using Euler theory. The local bulging behavior of the outer steel tube is analyzed with an equivalent beam model. The design recommendations for LPBRB are presented finally.

• Journal of Veterinary Clinics
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• v.39 no.6
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• pp.400-404
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• 2022

A 3-year-old Thoroughbred gelding presented with left laryngeal hemiplegia with a history of laryngoplasty (tie-back surgery) failure. Postoperative endoscopy revealed no abduction or no inflammatory changes in the left arytenoid cartilage. The owner opted for the horse to undergo partial arytenoidectomy due to failed laryngoplasty. A tracheostomy tube was intubated through a mid-cervical tracheotomy to secure the airway under general anesthesia, and; laryngotomy was performed to access the arytenoid cartilage in dorsal recumbency. A partial arytenoidectomy was performed with endoscopic assistance through the left nostril, and the left arytenoid cartilage was removed, excluding the muscular process. Antibiotic and anti-inflammatory agents were administered postoperatively, and the incision site was cleaned using normal saline and antibiotic ointment twice daily. On the 12th postoperative day, endoscopy revealed redundant corniculate process mucosa at the surgical site, which was removed using rongeur forceps directly through the previous laryngotomy incision. The horse showed no significant complications during the hospitalization. Two months after surgery, the surgical site reportedly recovered with no evidence of granulation tissue. The horse returned to training and racing 3 and 7 months postoperatively, respectively. This is the first case report of a partial arytenoidectomy in a horse in South Korea. In this case, the horse returned to training after partial arytenoidectomy without significant complications, indicating that partial arytenoidectomy could be beneficial for failed laryngoplasty.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.35-43
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• 2006

In this paper, procedures and research results involved in the development of glass reinforced composite bridge deck of hollow section were presented. Laminate design for the 3 cell deck section was performed. Structural characteristics such as serviceability, strength, failure and stability for DB24 load were analytically studied through the finite element analysis for the composite deck plate girder bridge. Composite deck tube was fabricated with pultrusion and extensive tests such as flexural test, girder-connection test, barrier-connection test, compression fatigue test and flexural fatigue test were carried out to evaluate structural behavior experimentally. Also, field load test was conducted for the demonstration plate girder bridge with composite deck and requirements for the strength and serviceability were reviewed.

• Journal of Chest Surgery
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• v.31 no.11
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• pp.1063-1069
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• 1998

Background: Multi-loculated empyema makes treatment difficult, and more so when thoracentesis or chest tube drainage fails. Materials and methods: From December 1991 to December 1997, we performed closed rib resectional drainage for 18 cases of loculated empyema on the fibrinopurulent or early chronic phase. Results: Surgery was performed on patients with loculated empyema complaining of persistent symptoms due to failure of treatment by thoracentesis(8 cases) or chest tube drainage(10 cases). Predisposing factors of empyema were pneumonia in 13 cases, clotted hemothorax in 3 cases, cholecystectomy, and tuberculous pleurisy in 1 case. Causal organisms were cultured in 8 cases(42.1%), and methicillin-resistant staphylococcus aureus was found in 3 cases, pseudomonas aeruginosa in 2 cases, and enterococcus aerogens, α-hemolytic streptococcus, and acinetobacter baumannii were found in 1 case. Size of loculations was various, and computed chest tomogram showed multiple loculations of empyema numbering 1∼4(mean 1.78±1.00). Operating time was relatively short, about 55∼140 mins(mean 102.8±30.8). All toxic symptoms including fever disappeared postopratively and general conditions improved very quickly in all patients. Length of chest tube indwelling time and hospital stay after surgery were 3∼42 days(mean 11.4±11.5) and 6∼36 days(mean 12.9±8.1), respectively. Complications of prolonged drainage occurred in 2 cases and no death occurred. There were no recurrences and chest x-rays taken 3∼6 months after surgery showed normal findings in 14 cases and slight pleural thickening in 4 cases. Conclusions: Closed rib resectional drainage requires very simple techniques and has excellent outcomes and little complications, therefore, we think that it is the choice of operation for patients with loculated empyema on the fibrinopurulent or early chronic phase.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.113-116
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• 2011

Purpose: Acetylcholine receptor antibodies cause acetylcholine receptor loss, which is responsible for failure of the neuromuscular junction in the acetylcholine receptor autoantibody. The disease characterized by muscle weakness and fatigue, myasthenia gravis(MG) occurs when the body inappropriately produces antibodies against acetylcholine receptors, and thus inhibits proper acetylcholine signal transmission. And this reason, the measurement of acetylcholine receptor antibodies can be of considerable value in disease diagnosis. Methods: From 2010. August to September, we tested orderd AchRAb 19 samples to get the results. 1. Pipette $5{\mu}{\ell}$ undiluted patient sera and kit control and add 125I AChR $50{\mu}{\ell}$ and incubate at R.T for 2 hours. 2. Pipette $50{\mu}{\ell}$ of anti-human IgG into each tube, and incubate at $2{\sim}8^{\circ}C$ for 2 hours. 3. Pipette $25{\mu}{\ell}$ precipitation enhancer into each tube and add 1mL washing solution into all tubes. 4. Centrifuge each tube for 20minutes at $2{\sim}8^{\circ}C$ at 1500g. 5. Aspirate or decant the supernatant. 6. Pipette 1 mL washing solution into all tubes and resuspend the pellet and repeat centrifugation. 7. Aspirate or decant the supernatant and count all tubes on a gamma counter. Results: Cut off value is 0.2 nmol/L and the results taken below 0.2 nmol/L are negative, the results above that identified as being positive values. We assayed the 19 patients samples and got 7 positive results. Of which, 6 patients were diagnosed as MG.(85.7%). Conclusions: Acetylcholine Receptor autoantibody test is intended for use by persons only for the quantitative determination of it in human serum. Even if measurement of the antibodies is not a routine test, it can be of considerable value in disease diagnosis.

• Tuberculosis and Respiratory Diseases
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• v.44 no.6
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• pp.1326-1331
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• 1997

Background : Weaning is the process of switching a patient from mechanical ventilator to spontaneous breathing. A number of different weaning techniques can be employed. At recent study, conventional spontaneous breathing trial was superior to other techniques, such as intermittent mandatory ventilation(IMV) or pressure support ventilation(PSV). But adequate observation time of the spontaneous breathing trial was not determined. We reported the effectiveness of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotrachial tube. In this study, we tried to shorten the spontaneous breathing time from 60 minutes to 30 minutes. If weaning success was predicted after 30 minutes spontaneous breathing, extubation was done without reconnection with ventilator. Methodes : Subjects consisted of 42 mechanically ventilated patients from August 1994 to July 1995. The weaning trial was done when the patients recovered sufficiently from respiratory failure that originally required ventilatory assistance, the patients became alert and showed stable vital sign, and arterial $O_2$ tension was adequated($PaO_2$ > 55 mmHg) with less than 40% of inspired oxygen fraction. We conducted a careful physical examination when the patients was breathing spontaneously through the endobronchial tube for 30 minutes. We terminated the trial if a patients was any of following signs of distress; cyanosis, diaphoresis, tachypnea(above 30 breaths per minute), and extreme tachycardia. Patients who had none of this features during spontaneous breathing for 30 minutes were extubated promptly. Result : 17 weaning trials of 15 patients were done in 42 mechanically ventilated patients. Successful weaning and extubation was possible in 14 trials of total 17 trials. In this 14 patients, 8 patients were extubated after 30 minutes spontaneous breathing, 3 patients were extubated after 60 minutes spontaneous breathing, and 3 patients needed over 3 hours for extubation from weaning. We found similar overall success rate compared with weaning following a 60 minutes spontaneous breathing trial. Conclusion : From the result of present study, we believe that weaning and extubation from mechanical ventilation following a 30 minutes spontaneous breathing with $O_2$ supply through the endotracheal tube is a simple and effective method.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.121-130
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• 2007

To investigate the enhancement in strength and deformation capacities of concrete confined by FRP composites, tests under axial loads were carried out on three groups of thirty six short columns in circular section with diverse GFRP confining reinforcement. The major test variables considered include fiber content or orientation, wrap or tube type by varying the end loading condition, and continuous or discontinuous confinement depending on the presence of vortical spices between its two halves. The circumferential FRP strains at failure for different types of confinements were also investigated with emphasis. Various analytical models capable of predicting the ultimate strength and strain of the confined concrete were examined by comparing to observed results. Tests results showed that FRP wraps or tubes provide the substantial increase in strength and deformation, while partial wraps comprising the vertical discontinuities fail in an explosive manner with less increase in strength, particularly in deformation. A bilinear stress-strain response was observed throughout all tests with some variations of strain hardening. The failure hoop strains measured on the FRP surface were less than those obtained from the tensile coupons in all tests with a high degree of variation. In overall, existing predictive equations overestimated ultimate strengths and strains observed in present tests, with a much larger scatter related to the latter. For more accuracy, two simple design- oriented equations correlated with present tests are proposed. The strength equation was derived using the Mohr-Coulomb failure criterion, whereas the strain equation was based on entirely fitting of test data including the unconfined concrete strength as one of governing factors.