• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.675-686
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• 2007

Statement of problem: Titanium nitride(TiN) coatings are the most general and popular coating method and used to improve the properties of metallic surface for industrial purposes. When TiN coating applied to the abutment screw, frictional resistance would be reduced, as a results, the greater preload and prevention of the screw loosening could be expected. Purpose: The purpose of this study was to investigate mechanical properties of TiN coated film of various coating thickness on the titanium alloy surface and to evaluate proper coating thickness. Material and method: 95 Titanium alloy (Ti-6Al-4V) discs of 15 mm in diameter and 3 mm in thickness were prepared for TiN coating and divided into 7 groups in this study. Acceding to coating deposition time (CDT) with TiN by using Arc ion plating, were divided into 7 groups : Group A (CDT 30min), Group B (CDT 60min), Group C (CDT 90min), Group D (CDT 120min), Group E (CDT 150min), Group F(CDT 180min) and Group G (no CDT) as a control group. TiN coating surface was observed with Atomic Force Microscope(AFM), field emission scanning electron microscopy(FE-SEM) and examined with scratch tester, wear tester. Result: 1. Coating thickness fir each coated group was increased in proportion to coating deposition time. 2. Surface of all coated groups except Group A was homogeneous and smooth. However, surface of none coated Group G had scratch. 3. Adhesion strength for each coated group was increased in proportion to coating deposition time. 4. Wear resistance for each coated group was increased in proportion to coating deposition time. 5. Surface roughness in Group A, B, C was increased in proportion to coating deposition time. But, surface roughness in Group D, E, F was showed decreased tendency in proportion to coating deposition time. Conclusion: According to coating deposition time, mechanical properties of TiN coated film were changed. It was considered that 120 minutes coating deposition time ($1.32{\mu}m$ in coating thickness) is necessary.

• Journal of Korean Foot and Ankle Society
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• v.17 no.2
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• pp.130-135
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• 2013

Purpose: Preshaped Locking compression plate(LCP) has holes with fixed angle between screw and plate and have advantage firm fixation because it has stability of angular and axial deformity. We evaluated usefulness of LCP after open reduction and internal fixation in distal fibular fracture. Materials and Methods: Between December 2011 and May 2012, 23 patients with fracture of distal fibula were followed up at least 12 months underwent open reduction and internal fixation with LCP. There were 15 males and 8 females with a mean age 39.8(20~69) years. According to Danis-Weber classification, there were 20 cases of type B and 3 cases of type C. There were 13 cases of isolated lateral malleolus fractures, 1 case of bimalleolar fracture, 6 cases of trimalleolar fractures and 3 cases of distal tibia fractures with proximal fibula fracture. Intraoperatively, we assessed whether preshaped LCP fit lateral margin of distal fibula or not and evaluated quality of reduction and postoperative complications. The cases were analyzed by radiological bone union time and clinical results according to the criteria of Meyer Results: Of all cases, complete bone union was achieved and average radiological bone union time was 7.3(6~12) weeks. The clinical results were excellent in 18 cases(78%), good in 5 cases(22%). There were 5 cases of plate with 3 holes, 13 cases of plate with 4 holes, 2 cases of plate with 5 holes, 1 case of plate with 6 holes and 2 cases of plate with 7 holes. The average number of screws at proximal fragement was 2.5 and at distal fragment was 3.5. In 14 cases (60.8 %), we needed re-bending of plate because the distance between plate and lateral cortical margin of distal fibula was more than 5 mm at anteroposterior X-ray after reduction. All cases have anatomical reduction and there were no complications of wound infections. There were no complaint about hardware irritation. Conclusion: At fractures of distal fibula,preshaped LCP had a excellent stability although far cortex was not fixed with screw and bending of plate. And there are less complications of hardware irritation and wound problems. But, Some complement would be needed because there were no complete fitting between precontour of LCP and lateral cortical margin of distal fibula.

• Clinics in Shoulder and Elbow
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• v.2 no.2
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• pp.126-132
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• 1999

Purpose : To evaluate the functional and radiographic outcome of the modified Bosworth method in the surgical treatment of acute type V acromioclavicular joint dislocation. Materials and Methods: From June 1995 to May 1998, 20 patients were operated on for acute and complete acromioclavicular dislocation(Rockwood type V). The operative technique includes fixation of the coracoclavicular joint with Bosworth screw or 6.5mm cancellous screw and imbrication of trapezius and deltoid muscles. The average age was 34 years(range, 19 to 51 years). These 20 patients with an average follow-up of 18months, were evaluated clinically using the UCLA scoring system. Additional radiographical assessment was performed with stress radiographs. Results: Excellent or good clinical results were obtained in 95%(19 cases). And the average coracoclavicular interval ratio was decreased from 3.31(2.2-6.0) to 1.13(1-1.4) in stress radiographs. There were 4 cases of hetero­topic calcification postoperatively but there was no correlation with clinical result. Posttraumatic A-C joint arthritis was developed in one case. In that case, the distal clavicular resection was done under the arthroscopic technique. Conclusion: The severe displacement observed with type V injuries is incompatible with normal shoulder function if the shoulder is left in its displaced position. In type V injuries, significant damage to the deltoid and trapezius musculature and overlying fascia occurs, therefore open reduction and good fixation must be obtained with imbrication of trapezius and deltoid muscles. In our type V acute complete acromioclavicular dislocation, the modified Bosworth technique provides excellent results with a low complication rate.

• The korean journal of orthodontics
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• v.33 no.2 s.97
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• pp.91-102
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• 2003

This study was performed to investigate the effect of immediate orthodontic force on soft md hard tissues surrounding C-Palatal $Plate^{TM}$ in beagle Dog. Immediately after this appliance was implanted on the midpalate of 4 adult beagle Dogs, 400gm continuous orthodontic force was applied. Experimental animals were euthanized at 8weeks, 18weeks, and 22weeks (including post-removal healing time of 4weeks), and a control animal was euthanized at 8weeks after implantation without orthodontic force application. The appliance and the surrounding tissue were studied radiographically, macroscopically, and histologically. The results were as follows: 1. The lateral radiographs taken after euthanasia showed very slight displacement of the vortical plate in the experimental animals, compared with the control animal. Mobility test of all animals confirmed primary stability without any increase of mobility during experimental period. 2. No pathologic changes were found in the healing condition of covering soft tissue and bone-screw interface in experimental animals as well as a control animal. 3. Osseointegration was achieved in the bone-screw interface in 8weeks after implantation and the amount of osseointegration increased in 18weeks. There was little difference of osseointegration between the compression side and the tension side. 4. In the marginal bone area, slight bone apposition and resorption were found regardless of compression and tension side, while there was no change in the control animal. 5. Both 8week-animal and 18week-animal showed the new bone apposition along the surface of screws which were perforated into the nasal cavity, while the control animal showed no change. 6. After 4weeks of plate removal, the covering epithelium was repaired intactly, while the connective tissue showed loose and irregular rearrangement and the connective tissue capsule remained. The C-Palatal $Plate^{TM}$ manifested sufficient anchorage capacity in the context of histological study as well as clinical outcomes, when immediate orthodontic force was applied after implantation.

• Journal of the Korea Institute of Building Construction
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• v.24 no.3
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• pp.331-341
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• 2024

In this study, the flexural strength and ductility of steel-timber composite beams were evaluated to enhance the structural performance of glued-laminated timber beams. Three specimens were fabricated, including one reference glulam beam and two composite beams. The composite beams were constructed by attaching steel sections to the glulam beam using either liquid adhesive or screws. The experimental results showed that the structural performance of the steel-timber composite beams was approximately 2-3 times higher than the reference glulam beam, indicating that both flexural strength and ductility were sufficiently ensured. Notably, the specimen constructed with liquid adhesive demonstrated superior structural performance compared to the screw-attached specimen.

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1946-1952
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• 2005

New group 15 organometallic compounds, M$(phenanthrenyl)_3$ (M = P (1), Sb (2), Bi (3)) have been prepared from the reactions of 9-phenanthrenyllithium with $MCl_3$. A reaction of 9-(diphenylphosphino)phenanthrene with 2,6-diisopropylphenyl azide led to the formation of (phenanthrenyl)${(Ph)}_2P$=N-(2,6-$^iPr_2C_6H_3$) (4). The crystal structures of 2 and 4 have been determined by single-crystal X-ray diffractions, both of which crystallize with two independent molecules in the asymmetric unit. Compound 2 shows a trigonal pyramidal geometry around the Sb atom with three phenanthrenyl groups being located in a screw-like fashion with an approximately $C_3$ symmetry. A significant amount of CH- -$\pi$ interaction exists between two independent molecules of 4. The phosphorus center possesses a distorted tetrahedral environment with P-N bond lengths of 1.557(3)$\AA$ (P(1) N) and 1.532(3)$\AA$ (P(2)-N), respectively, which are short enough to support a double bond character. One of the most intriguing structural features of 4 is an unusually diminished bond angle of C-N-P, attributable to the hydrogen bonding of N(1)-H(5A) [ca. 2.49$\AA$ between two adjacent molecules in crystal packing. The compounds 1-3 show purple emission both in solution and as films at room temperature with emission maxima ($\lambda_{max}$) at 349, 366, and 386 nm, respectively, attributable to the ligand centered $\pi$ $\rightarrow$ $\pi^\ast$ transition in phenanthrene contributed by the lone pair electrons of the Gp 15 elements. Yet the nature of luminescence observed with 4 differs in that it originates from $\pi$ (diisopropylbenzene)-$\pi^\ast$ (phenanthrene) transitions with the $\rho\pi$contribution from the nitrogen atom. The emission maximum of 4 is red-shifted ranging 350-450 nm due to the internal charge transfer from the phenanthrenyl ring to the N-arylamine group as deduced from the ab initio calculations.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.305-309
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• 1994

Precooked powder of redbean porridge (RP) was prepared by the series of process extrusion, drying, milling and blending with a mixture of whole redbean flour and corn starch and others. The optimum process and quality of products for RP were investigated. After extrusion under the moisture content 24 to 26%, twin screw speed 350 rpm, extrusion temperature 150 to $155^{\circ}C$ and feed rate 60 kg/hr, the product had a higher quality with its natural redbean flavor/color. During the extrusion process, extrusion temperature and specific mechanical energy increased from 150 to $198^{\circ}C$ and from 134 to 144 kwh/ton respectively, as the amount of addition water decreased from 6 to 2 kg/hr. By the hot air drying of redbean extrudate (RE). it could be dried below to 4% moisture content, of which level considered as an optimal moisture content for anti-caking of the powdered product, at $80^{\circ}C$ for 4hrs and at $100^{\circ}C$ for 1.5 hrs respectively. In the sieve analysis of extrudate powder, when the product milled through a mesh size of 0.5 mm or 1.0 mm, about 80% or 65% of the feed was passed a 65 mesh screen respectively. Moisture absorption of final blended products was formed a cake under 100% of relative humidity after 13 hrs of storage. As the amount of RE powder reduced, the flavor score of products decreased by sensory evaluation of products prepared by the different ratio of RE powder, corn starch and sugar.

• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.10-21
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• 2006

Recycled polypropylene (RPP) - Wood Saw Dust (WSD) composites with and without acetylation of filler were produced at different filler loading (15%, 25%, 35% and 45% w/w) and filler size (300, 212 and $100{\mu}m$). The RPP-WSD was compounded using a Haake Rheodrive 500 twin screw compounder at $190^{\circ}C$ at 8 MPa for 30 minutes. The mechanical properties and water absorption properties of modified and unmodified WSD-PP composites were investigated. Acetylation of WSD improved the mechanical and water absorption characteristic of composites. The decrease of filler size (300 to $100{\mu}m$) of the unmodified and acetylated WSD showed increase of tensile strength and impact properties. The composites exhibited higher tensile modulus properties as the filler loading increased (15% to 45%). However tensile strength, elongation at break and impact strength showed the opposite phenomenon. Water absorption increased as the mesh number and filler loading increased. With acetylation, lower moisture absorption was observed as compared to unmodified WSD. The failure mechanism from impact fracture of the filler-matrix interface with and without acetylation was analyzed using Scanning Electron Microscope (SEM).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.2
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• pp.234-248
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• 1995

A super-heat pump system composed of a suction line heat exchanger, low and high stage economizers, and a screw compressor is simulated to examine the energy performance and design options. CFC12, HCFC22, HFC134a, HCFC22/HCFC142b, HFC32/HFC134a, and HFC125/HFC134a are used as working fluids for comparison. The results indicate that the proposed system charged with appropriate mixtures is up to 33.4% more energy efficient than the normal system with CFC12. The performance of the super-heat pump system charged with mixtures was influenced by such factors as the temperature matching, heat source temperature difference, low stage economizer, and high stage economizer. The fluids with a larger liquid specific heat such as HFC134a would have more benefits when a suction line heat exchanger is installed. 40%HCFC22/60%HCFC142b mixture seems to be a good candidate to replace CFC12. On the other hand, 25%HFC32/75% HFC134a would be a good long term candidate to replace HCFC22.

• Transactions of Materials Processing
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• v.16 no.5 s.95
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• pp.354-359
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• 2007

Effects of forging and mechanical properties of 6061 aluminum alloy wheel for automobiles were investigated in the present study. Microstructural and tensile characteristics of automobile wheel after hot forging process using dynamic screw press were analyzed to evaluate effect of metal flow on mechanical properties. The results showed advanced mechanical properties of 6061 alloy wheel because of $Mg_2Si$ precipitation by T6, elongated grain by forging, and work hardening by dense metal flow, etc. Hot compression tests were conducted in order to characterize high temperature compression deformation behaviors and microstructural variation in the range of $300{\sim}450^{\circ}C$, in the strain rate range of $10^{-3}{\sim}10^1\;sec^{-1}$. As strain rate increased, maximum compression stress increased but it was shown the reverse linear relation between temperature and maximum stress irrelevant to strain rate variation. On the other hand, temperature and yield stress didn't have any linear relation and its relation showed big deviation by a function of strain rate and test temperature.