• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제40권6호
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• pp.285-290
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• 2014

Objectives: We compared resorbable plates with titanium plates for treatment of combined mandibular angle and symphyseal fractures. Materials and Methods: Patients with mandibular angle and symphysis fractures were divided into two groups. The control (T) group received titanium plates while the experimental (R) group received resorbable plates. All procedures were carried out under general anesthesia using standard surgical techniques. We compared the frequency of wound dehiscence, development of infection, malocclusion, malunion, screw breakage, and any other technical difficulties between the two groups. Results: Thirteen patients were included in the R group, where 39 resorbable plates were applied. The T group consisted of 16 patients who received 48 titanium plates. The mean age in the R and T groups was 28.29 and 24.23 years, respectively. Primary healing of the fractured mandible was obtained in all patients in both groups. Postoperative complications were minor and transient. Moreover, there were no significant differences in the rates of various complications between the two groups. Breakage of 3 screws during the perioperative period was seen in the R group, while no screws or plates were broken in the T group. Conclusion: Resorbable plates can be used to stabilize combined mandibular angle and symphysis fractures.

• The Journal of the Korean dental association
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• 제48권3호
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• pp.205-217
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• 2010

Purpose The aim of this study is to evaluate the survival rates and analyze the stability of lateral approach and trans-crestal approach for maxillary sinus floor elevation of simultaneous implant placement. Materials and method 407 patients who have been treated in LivingWell dental hospital between 2003 to 2009 were selected. Lateral window technique, osteotome technique and sinus drill technique were used for sinus floor elevation procedure. A total of 714 implants-MP-1 HA coated implant(Tapered Screw $Vent^{TM}$, $Spline^{TM}$, Zimmer, USA), FBR surfaced implant(Pitt-$Easy^{TM}$, Oraltronics, Germany)-were placed in grafted maxillary sinus simultaneously. The autogenous bone or a combination with the allograft or alloplast was grafted into sinus. Sinus floor elevation was combined with vertical/horizontal onlay bone grafts to reconstruct the defect of alveolar ridge. Results The average preoperative height of the maxillary alveolar bone was 5.78mm(range: 0.4mm~12.5mm). 14 implants failed during the healing period(lateral approach: 4, trans-crestal approach: 10) and 3 implant failed after prosthetic loading(lateral approach: 2, trans-crestal approach: 1). The cumulative survival rate of implants after 6 years was 97.6%. Trans-crestal approach(97.4%) and lateral approach(97.9%) had similar survival rates. Conclusion The results indicate that the trans-crestal approach and lateral approach for maxillary sinus elevation is a acceptable method at atrophic maxillary posterior area.

• Food Science and Biotechnology
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• 제14권3호
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• pp.305-310
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• 2005

Flaxseed is outstanding for lignans and oil rich in ${\alpha}$-linolenic acid which protect against several major illnesses. Better understanding of processing and storage characteristics of flaxseed will increase options for food use. Lignans and oil are found in the hull and embryo, respectively. Comparison of pearling and impact-dehulling processes for separation of lignan and oil-rich fractions showed the impact process was less effective, but easier to scale-up. Screw-pressing embryo reduced oil yield compared to whole seed, but doubled productivity and sharply reduced frictional heating of the oil. Flaxseed hull and embryo, also whole, ground and steamed-ground samples, were stable up to 30 weeks in closed containers at $23^{\circ}C$. Steamed-ground samples in open trays at $40^{\circ}C$ deteriorated markedly (peroxide value > 100 by 22 weeks); yet, whole seed remained stable. Incorporation of 18% flaxseed embryo into yellow perch feed increased ${\alpha}$-linolenic acid to 13 to l4% of muscle and liver lipids, compared to 0.5 to 0.7% in the no-embryo control. Feed conversion ratio, weight gain, and survival were similar. These studies are helping to establish the technological base for processing and utilizing flaxseed and flaxseed fractions to improve human diets.

• Journal of Adhesion and Interface
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• 제15권1호
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• pp.14-21
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• 2014

In the present work, PLA/PBS blends with poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) at different contents were processed by using a twin-screw extruder and an injection molding machine, and then their mechanical, thermal and morphological properties were investigated. The mechanical properties such as flexural strength, flexural modulus, tensile strength and tensile modulus and thermal properties such as melting behavior, dynamic mechanical thermal properties and thermal stability significantly depended on the contents of PLA and PBS. However, the heat deflection temperature of the blends was not significantly influenced by the contents of PLA and PBS. Also, the fracture surfaces of PLA/PBS blends were changed from a brittle pattern to a ductile pattern with increasing the PBS contents.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• 제27권1호
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• pp.41-48
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• 2021

In this study, ethylene vinyl acetate (EVA) and low density polyethylene (LDPE) composite films (EVA/LDPE-OSP) containing calcined oyster shell powder (OSP) were prepared using twin-screw extruder as an antimicrobial packaging material. The OSP composite was initially prepared and then incorporated into an EVA/LDPE blend at different ratios (0, 1, 3 and 5%) to develop the EVA/LDPE-OSP composite films. The as-prepared EVA/LDPE-OSP composites films were evaluated using FT-IR, DSC, TGA, OTR, WVTR, SEM and UTM as well as antimicrobial activity was examined using JIS Z 2801:2000 standard. OPS endowed the antimicrobial potency to the composite films against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. In addition, the incorporation of OSP remarkably enhanced the thermal stability. OSP as a natural biocidal agent can be used as a multifunctional additive in packaging industry such as improving the thermomechanical properties and preventing the microbial contamination of packaged products.

• Tribology and Lubricants
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• 제35권1호
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• pp.65-70
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• 2019

Self-loosening of bolts owing to external forces occurs in several machines that are clamped by bolts and nuts. This study focuses on the self-loosening of the aiming bolt of the head lamp in a vehicle. It is important to prevent the aiming bolt from self-loosening as it has a decisive effect on the angle of the head lamp. A nut clamped with a bolt, known as a retainer, is made of plastic and has a partial screw thread. In addition, a transverse load has a considerable impact on the self-loosening of a bolt. We concentrate on the self-loosening of a bolt by a transverse load. The aim of this study is to define the limits of the external force that loosen the bolt. Based on the above conditions, we derive a theoretical equation and develop a numerical analysis program that can calculate the limiting forces for self-loosening. To verify the developed program, we design a test device that can measure the self-loosening by applying sliding forces to the aiming bolt. Using this method, we can draw the following conclusions. First, the developed testing device is suitable to prove the theory for calculating the self-loosening force. Second, the equation confirms the relationship of bolt self-loosening between resistance torque and shear force. Finally, the equation obtains the minimum value of the resistance torque required to decrease the change in the angle of the head lamp, thereby improving the possibility of increasing the stability of the head lamp.

• The Journal of Advanced Prosthodontics
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• 제13권6호
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• pp.396-407
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• 2021

PURPOSE. Zirconia has exceptional biocompatibility and good mechanical properties in clinical situations. However, finite element analysis (FEA) studies on the biomechanical stability of two-piece zirconia implant systems are limited. Therefore, the aim of this study was to compare the biomechanical properties of the two-piece zirconia and titanium implants using FEA. MATERIALS AND METHODS. Two groups of finite element (FE) models, the zirconia (Zircon) and titanium (Titan) models, were generated for the exam. Oblique (175 N) and vertical (175 N) loads were applied to the FE model generated for FEA simulation, and the stress levels and distributions were investigated. RESULTS. In oblique loading, von Mises stress values were the highest in the abutment of the Zircon model. The von Mises stress values of the Titan model for the abutment screw and implant fixture were slightly higher than those of the Zircon model. Minimum principal stress in the cortical bone was higher in the Titan model than Zircon model under oblique and vertical loading. Under both vertical and oblique loads, stress concentrations in the implant components and bone occurred in the same area. Because the material itself has high stiffness and elastic modulus, the Zircon model exhibited a higher von Mises stress value in the abutments than the Titan model, but at a level lower than the fracture strength of the material. CONCLUSION. Owing to the good esthetics and stress controllability of the Zircon model, it can be considered for clinical use.

• Journal of Korean Foot and Ankle Society
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• 제27권2호
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• pp.58-66
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• 2023

Purpose: This study aimed to evaluate the effectiveness of deltoid ligament repair on syndesmotic stabilization in patients with acute ankle fractures with ruptured deltoid and syndesmotic ligaments. Materials and Methods: The medical records of 41 patients (41 ankles) who underwent surgery for Weber type B ankle fracture with ruptured deltoid and syndesmotic ligaments were retrospectively analyzed. The mean follow-up duration was 36 months (range 18~65 months). Patients were divided into two groups: those that underwent deltoid ligament repair (the deltoid group) and those who did not (the non-deltoid group). Both groups were also divided into two subgroups, namely, the D1/S1 group, which underwent syndesmotic screw fixation, or the D2/S2 group, which did not. Medial clear space (MCS), tibiofibular clear space (TFCS), anterior fibular line (AFL) ratio, and posterior fibular line (PFL) distance were measured, and visual analog scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS), and Foot Function Index (FFI) scores were evaluated. Results: TFCS changed significantly after surgery in the D2 and S1 groups (p=0.01, p=0.03, respectively). Subgroup MCSs, TFCSs, and AFL ratios were not significantly altered by surgery in the four subgroups (p=0.82, p=0.45, p=0.25, respectively). However, postoperative PFL distances were significantly different in the D2 and S1 groups and the S1 and S2 groups (p=0.02, p=0.02, respectively). Mean TFCS decreased significantly after surgery in the D2 and S1 groups. The postoperative VAS, AOFAS scores, and FFI were not significantly different between the subgroups (p=0.44, p=0.40, and p=0.46, respectively). Conclusion: Deltoid ligament repair seemed to restore ankle stability without addressing syndesmosis in Weber type B ankle fractures with rupture of deltoid and syndesmotic ligaments.

• Journal of the Korean Wood Science and Technology
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• 제50권2호
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• pp.134-147
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• 2022

The objective of this study is to determine the effect of fiber direction arrangement and layer composition of hybrid bamboo laminate boards on the physical and mechanical properties. The raw material used was tali bamboo (Gigantochloa apus (J.A. & J.H. Schultes) Kurs) rope in the form of flat sheets (zephyr) and falcata veneer (Paraserianthes falcataria (L) Nielsen). Zephyr bamboo was arranged in three layers using water-based isocyanate polymer (WBPI) with a glue spread rate of 300 g/m². There were variations in the substitution of the core layer with falcata veneers (hybrid) as much as two layers and using a glue spread rate of 170 g/m². The laminated bamboo board was cold-pressed at a pressure of 22.2 kgf/cm² for 1 h, and the physical and mechanical properties were evaluated. The results showed that the arrangement of the fiber direction significantly affected the dimensional stability, modulus of rupture, modulus of elasticity, shear strength, and screw withdrawal strength. However, the composition of the layers had no significant effect on the physical and mechanical properties. The bonding quality of bamboo laminate boards with WBPI was considered to be quite good, as shown by the absence of delamination in all test samples. The bamboo hybrid laminate board can be an alternative based on the physical and mechanical properties that can meet laminated board standards.

• Journal of the Korean Arthroscopy Society
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• 제3권1호
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• pp.17-23
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• 1999

Purpose : We intend to review clinical results after Anterior cruciate ligament(ACL) reconstruction using hamstring tendon arthroscopically. Materials & Methods : Sixty two patients who had underwent arthroscopic ACL reconstruction using hamstring tendon from Mar. 1996 to Mar. 1997 were reviewed. The average follow-up was 16 months and average age at operation was 27 years old. Clinical results were evaluated with physical examination, Lysholm Knee score and instrumented anterior laxity test with Telos Results : The average preoperative Lysholm knee score was 57.0 and postoperative average of that was 91.8. All cases of 62 patients had normal range of motion of knee and were able to walk with no problems at follow-up. On the Lachmann test, there were mild(+) instability in 24 cases, moderate(++) in 24 cases, severe(+++) in 14 cases preoperatively and 48 cases were converted to negative, 14 cases mild postoperatively. On instrumented anterior laxity test with Telos, difference between normal and affected knee on 20 lb which was 13.4mm preoperatively was decreased to 4.7mm at follow-up and anterior stability was regained(P<0.05). Parapatellar complications such as crepitus in 18 cases(29.5%), atrophy of quadriceps in 23 cases(36.5%) were observed. There were 2 cases of inaccuracy of guide pin of semifix screw intraoperatively and 3 cases of malposition of semifix screw postoperatively. Conclusion : ACL reconstruction using hamstring tendon seems to be a effective procedure to establish the stability of knee joint but is technically demanding procedure and leaves some parapatellar complications.