• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.261-268
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• 2014

Precision screws have a wide range of industrial applications such as electrical and automotive products. To produce screw threads with high precision, not only high precision manufacturing technology but also reliable measurement technology is required. Machine vision systems have been used in the automatic inspection of screw threads based on backlight illumination, which cannot detect defects on the thread surface. Recently, an omnidirectional inspection system for screw threads was developed to obtain $360^{\circ}$ images of screws, based on front light illumination. In this study, the illumination design for the omnidirectional inspection system was modified by adding a light shield to improve the image uniformity. Optical simulation for various shield designs was performed to analyze image uniformity of the obtained images. The simulation results were analyzed statistically using response surface method, from which optical performance of the omnidirectional inspection system could be optimized in terms of image quality and uniformity.

• Clinics in Shoulder and Elbow
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• v.19 no.1
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• pp.43-47
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• 2016

Many types of osteotomy have been proposed for the treatment of cubitus varus deformity of the elbow, and various methods for fixation of the osteotomy site have also been described. However, no method has been perfect. We treated two cases of cubitus varus elbow deformity with step-cut osteotomy using a new fixation method with two crossing screws and an anatomically designed locking plate. Active assisted elbow range of motion (ROM) exercise was permitted at postoperative 3 days, after removal of the drainage. Preoperative and postoperative humerus-elbow-wrist angles and ranges of motion of the two patients were compared. At 3 months followup, each patient had recovered the preoperative elbow ROM, and achieved the complete bony union of the osteotomy site and proper correction of the cubitus varus deformity. In addition, the appropriate remodeling of the lateral bony protrusion was observed. Therefore, we introduce a new fixation method for achievement of stable fixation allowing immediate postoperative elbow motion after corrective osteotomy for cubitus varus deformity in young adults.

• Journal of Veterinary Clinics
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• v.35 no.1
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• pp.30-33
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• 2018

A 7-month-old female Bichon Frise, displaying neck pain and ataxia, was diagnosed with craniocervical junction abonormality (CJA), along with atlantoaxial subluxation. Surgical fixation of the atlantoaxial subluxation was performed, using cortical screws and bone cement, along with an odontoidectomy. After surgery, nonsteroidal anti-inflammatory medication was prescribed for pain control, and a loose bandage was applied to the neck. Mild ambulatory tetraparesis remained 1 week after surgery. Three weeks after surgery, the range of neck motion was near normal, and clinical signs had improved. CJA should be considered as a differential diagnosis in dogs with cervical myelopathy. Surgical stabilization using cortical screws and bone cement through a ventral approach can be successful in dogs with CJA and atlantoaxial subluxation.

• Journal of the Korean Wood Science and Technology
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• v.41 no.6
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• pp.544-550
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• 2013

Tests were carried out on commercial particleboards manufactured in Korea to evaluate and modify formulas which had previously been developed to predict the holding loads of screw on the face and edge of specimen. Screw sizes were No. 6, 8 and 10 used in this study. The withdrawal loads of screws were developed to predict as a function of screw diameter, depth of penetration, specific gravity and IB of particleboard. Predicted equations were fitted to the test results of different length of No. 8 screws. Results of tests indicate that IB is a better predictor of holding loads on the face of particleboard than SG. On the other hand, SG is a good indicator of holding load on the edge of particleboard.

• Journal of Veterinary Clinics
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• v.36 no.5
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• pp.292-295
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• 2019

A 2-year-old, 440 kg, thoroughbred gelding showed a lameness grade of 3 out of 5, as well as swelling and heating on the proximal interphalangeal joint (PIPJ). Periarticular new bones due to the arthritis were observed on performing radiography and ultrasonography. PIPJ arthrodesis was performed under general anesthesia. With the PIPJ open, the articular cartilage was removed by using curette, chisel, and mallet. Arthrodesis was performed with a PIP plate and two additional transarticular cortex screws inserted in lag fashion. A cast was placed over the limb distal from the proximal metatarsal bone. At 6 months after surgery, complete union of the PIPJ was confirmed by radiography, and the incision site was well closed. Based on the outcome, a PIP plate with two additional transarticular cortex screws inserted in lag fashion is recommended as a method for treating osteoarthritis of the PIPJ in horses.

• The Journal of Advanced Prosthodontics
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• v.13 no.1
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• pp.65-70
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• 2021

Purpose. Implant mechanical complications, including screw loosening, can influence dental implant success. It has been shown that torque values are affected by contamination occurred in implant-abutment (I/A) interface. This study aimed to examine the effects of blood, saliva, fluoride and chlorhexidine contamination on reverse torque values (RTVs) of abutment screws in oral conditions. Materials and Methods. 50 fixtures were mounted into the stainless-steel holders and divided into five groups (n = 10). Except control group (NC), fixture screw holes in other groups were contaminated with chlorhexidine (CG), saliva (SG), blood (BG), or fluoride (FG). Abutment screws were tightened with a digital torque meter. I/A assemblies were subjected to thermocycling and cyclic loading. The mean RTVs were recorded and data were analyzed with one-way ANOVA and Tukey test. Results. Except for specimens in SG (20.56 ± 1.33), other specimens in BG (21.11 ± 1.54), CG (22.89 ± 1.1) and FG (24.00 ± 1.12) displayed significantly higher RTVs compared to NC (19.00 ± 1.87). The highest RTVs were detected in CG and FG. Conclusion. The obtained data robustly suggest that RTVs were significantly affected by fluid contaminations. Specimens in FG and CG displayed the highest RTVs. Therefore, clinicians should have enough knowledge about probable contaminations in I/A interface in order to manage them during clinical procedure and to inform patients about using oral care products.

• Steel and Composite Structures
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• v.42 no.3
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• pp.315-323
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• 2022

Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self-tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.54-65
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• 1993

The paper describes and alternative method based on a new idea to measure the circular movement of machining centers. ISO has employed three testing methods for the acceptance tests of machine tools; the first is a rotating one-dimensional probe method, the second is a two-dimensional probe and a master circular ring, and the third is a kinematic ball bar. The last two methods were proposed and introduced by W. Knapp and J. B. Bryan, respectively. The newly developed method is superior to above two methods; the rotating angle can be detected and the rotating radius is variable. Circular movement errors of machining centers were investigated by the analysis of data measured by R- .THETA. method. Followint observations are obtained 1) The errors which depend on positions, i.e., periodical errors by the pitch of ball screws, errors by compensation of backlash and errors by perpendicularity of X and Y-axis, were analyzed. 2) The errors which depend on NC control system, i.e., errors by the unbalance of position-loop-gaians, errors by velocity-loop-gains and errors by feed speeds, were quantiatively analyzed. 3) The method of extracting error information, which uses moving technique of averaging angle and fourier's analysis data mesured by the R- .THETA. method, was proposed.

• Journal of the Korean Orthopaedic Association
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• v.56 no.5
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• pp.419-426
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• 2021

Purpose: In the surgical treatment of pyogenic lumbar spondylodiscitis, screw insertion at the affected vertebra has been avoided because of biofilm formation, and the risk of infection recurrence. The authors analyzed the success rate of infection treatment while minimizing the number of instrumented segments by inserting pedicle screws into the affected vertebrae. Therefore, this study examined the usefulness of this technique. Materials and Methods: From January 2000 to June 2018, among patients with pyogenic lumbar spondylodiscitis treated surgically, group A consisted of patients with pedicle screws inserted directly at the affected vertebrae (28 cases), and group B underwent fusion by inserting screws at the adjacent normal vertebrae due to bone destruction of the affected vertebral pedicle (20 cases). The classified clinical results were analyzed retrospectively. All patients were treated via the posterior-only approach, so the affected disc and sequestrum were removed. Posterior interbody fusion was performed with an autogenous strut bone graft, and the segments were then stabilized with pedicle screw systems. The hospitalization period, operation time, amount of blood loss, EQ-5D index, duration of intravenous antibiotics, and the clinical and radiological results were analyzed. Results: In group A, the number of instrumented segments, operation time, blood loss, and EQ-5D index at one month postoperatively showed significant improvement compared to group B. There were no significant differences in the duration of antibiotic use, hospitalization, radiological bone union time, sagittal angle correction rate, and recurrence rate. Conclusion: Minimal segmental fixation, in which pedicle screws were inserted directly into the affected vertebrae through the posterior approach, reduced the surgery time and blood loss, preserved the lumbar motion by minimizing fixed segments and showed rapid recovery without spreading or recurrence of infection. Therefore, this procedure recommended for the surgical treatment of lumbar pyogenic spondyodiscitis.

• Journal of Korean Neurosurgical Society
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• v.61 no.4
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• pp.494-502
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• 2018

Objective : The loosening of pedicle screws (PS) is one of the frequent problems of spinal surgery in the patients with osteoporosis. Previous studies had revealed that intermittent injection of teriparatide could reduce PS loosening by improving bone mass and quality when their patients took parathyroid hormone for a considerable duration before surgery. However, although the teriparatide is usually used after spine surgery in most clinical situations, there was no report on the efficacy of teriparatide treatment started after spine surgery. The purpose of this retrospective study was to examine the efficacy of teriparatide treatment started immediately after lumbar spinal surgery to prevent pedicle screw loosening in patients with osteoporosis. Methods : We included 84 patients with osteoporosis and degenerative lumbar disease who underwent transforaminal interbody fusion and PS fixation and received parathyroid hormone or bisphosphonate (BP) postoperatively. They were divided into teriparatide group (daily injection of $20{\mu}g$ of teriparatide for 6 months, 33 patients, 172 screws) and BP group (weekly oral administration of 35 mg of risedronate, 51 patients, 262 screws). Both groups received calcium (500 mg/day) and cholecalciferol (1000 IU/day) together. The screw loosening was evaluated with simple radiographic exams at 6 and 12 months after the surgery. We counted the number of patients with PS loosening and the number of loosened PS, and compared them between the two groups. Clinical outcomes were evaluated using visual analog scale (VAS) and Oswestry disability index (ODI) preoperatively, and at 12 months after surgery. Results : There was no significant difference in the age, sex, diabetes, smoking, bone mineral density, body mass index, and the number of fusion levels between the two groups. The number of PS loosening within 6 months after surgery did not show a significant difference between the teriparatide group (6.9%, 12/172) and the BP group (6.8%, 18/272). However, during 6-12 months after surgery, it was significantly lower in the teriparatide group (2.3%, 4/172) than the BP group (9.2%, 24/272) (p<0.05). There was no significant difference in the number of patients showing PS loosening between the teriparatide and BP groups. The teriparatide group showed a significantly higher degree of improvement of the bone mineral density (T-score) than that of BP group (p<0.05). There was no significant difference in the pre- and post-operative VAS and ODI between the groups. Conclusion : Our data suggest that the teriparatide treatment starting immediately after lumbar spinal fusion surgery could reduce PS loosening compared to BP.