• International Journal of Automotive Technology
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• v.5 no.4
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• pp.247-255
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• 2004

The majority of real world frontal collisions involves partial overlap (offset) collision, in which only one of the two longitudinal members is used for energy absorption. This leads to dangerous intrusions of the passenger compartment. Excessive intrusion is usually generated on the impacted side causing higher contact injury risk on the occupants compared with full frontal collision. The ideal structure needs to have extendable length when the front-end structure is not capable to absorb crash energy without violating deceleration pulse requirements. A smart structure has been proposed to meet this ideal requirement. The proposed front-end structure consists of two hydraulic cylinders integrated with the front-end longitudinal members of standard vehicles. The work carried out in this paper includes developing and analyzing mathematical models of two different cases representing vehicle-to-vehicle and vehicle-to-barrier in full and offset collisions. By numerical crash simulations, this idea has been evaluated and optimized. It is proven form numerical simulations that the smart structures bring significantly lower intrusions and decelerations. In addition, it is shown that the mathematical models are valid, flexible, and can be used in an effective way to give a quick insight of real life crashes.

• Archives of Reconstructive Microsurgery
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• v.15 no.2
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• pp.111-116
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• 2006

An infection after total knee arthroplasty has many complications such as severe bone defect, skin and soft tissue problems, devastated general condition, so arthrodesis is preferred as treatment option. However, poor bony contact due to severe bone defect and inadequate conditions of the soft tissue often cause nonunion or severe limb shortening after arthrodesis. More over these conditions, it is not easy to choose appropriate fixative devices. In these situations, the arthrodesis using vascularized fibular graft can be the solution. Vascularized fibular graft (VFG) can playa role as a suitable material for the treatment of bone defects. And VFG can overcome poor blood circulation caused by scar tissues, and can be relatively more durable and adequate length. In the long term, VFG can be hypertrophied by weight bearing, and will give mechanical stablility. The purpose of the paper is to report the successful results of arthrodesis using VFG in a patient who got extensive bone defect after failed revision total knee arthroplasty with infection.

• Journal of the korean academy of Pediatric Dentistry
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• v.21 no.2
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• pp.491-495
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• 1994

The ectopic eruption is defined rise to be abnormal eruption, which gives to displacement of the teeth and abnormal root resorption of adjacent teeth. The ectopic eruption of first permanent molar is approximately 2-4% of the population, most of them are in the maxilla, rarely in the mandible. In the case of the second permanent molars, most of them are found in the mandible for the reason of the arch length discrepancies and large size of the teeth. The ectopic erupted molars should be treated early in order to coordinate normal growth pattern and to obtain good occlusal support. So, this should be early diagnosed and treated. But, ectopically erupting molars are often self-corrected, hence periodic follow-up is required. The methods of the treatment are largely classified into surgical, surgical-orthodontic, and orthodontic method. Especially in orthodontic method, they are divided as follows; appliances that is positioned at the contact point for unlocking and the distal movement, fixed and removable appliance that is connected to more than one tooth, and occlusion guiding method after disking or extraction of the second deciduous molar. The report presents the good results in treating patients, whose chief complaint was ectopic eruption of mandibular permanent molars.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1540-1546
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• 2000

Recently, force measurement systems are commonly used in many industrial fields and the precision of the measurement system is getting more important as the industry needs more precise tools and in struments to make high quality products. However, a high precision force measurement system is hard to make unless we know precisely the causes, quality and quantity of measurement errors in advance. In this work, many possible mechanical causes of measurement errors are reviewed including ratio of length to diameter of sensing part, radius of contact area, radius of bearing part, ratio of material properties and change of boundary conditions. Also, the measurement errors are analyzed by nonlinear finite element method and the nonlinear behavior of the errors are investigated. The results can be used to design force measurement systems and expected to be very useful especially for compact type load cells.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.698-704
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• 2010

The machine vision system has been widely applied at automatic inspection field of the industries. Especially, the machine vision system shows good performance at difficult inspection field by contact method. In this paper, the automatic system of a slant method to inspect screw/bolt shape using machine vision is developed. The inspection system uses pattern matching method that search similar degree of the lucidity, the average lucidity, length and angle of inspection set up area using a circular scan and a line scan method. Also the feeding method for inspection product is the slant method, and feed rate is controlled by the ramp angle adjustment. This inspection system is composed of a feeding device, a transfer device, vision systems, a lighting device and computer, and is composed the sorting discharge system of the inferior product. The performance test carried out the feeding speed, the shape correct degree and the sorting discharge speed according to the type of screw/bolt. This sorting inspection system showed a satisfied test results in whole inspection items. Presently, this sorting inspection system is being used in the manufacturing process of screw/bolt usefully.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.217-223
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• 2016

In this paper, the movement of a liquid metal droplet in a channel by continuous electrowetting effect is analyzed. The channel is fabricated using two glass substrates and silicone rubber as spacers, and a mercury droplet and dilute sulfuric acid are added into the channel. The droplet is moved according to voltage applied at both ends of the channel through an electrolyte. According to the shape of the droplet and the applied voltage, the velocity of the droplet is changed. The velocity is proportional to the applied voltage and inversely proportional to the length of the droplet, both theoretically and experimentally. Contact angle hysteresis and a meniscus change were also found in the moving state. This implies the existence of a threshold in movement by Laplace pressure difference. The experiment indicated that the sliding angle was inversely proportional to the width of the droplet but that the voltage threshold was proportional to the width.

• Journal of Powder Materials
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• v.11 no.6 s.47
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• pp.462-466
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• 2004

The bi-materials composed of $Al-5wt{\%}Mg$ and its composite reinforced with SiC particles were prepared by ball-milling and subsequent sintering process. The size of powder in Al-Mg/SiCp mixture decreased with increasing ball-milling time, it was saturated above 30 h when the ball and powder was in the ratio of 30 to 1. Both $Al-5wt{\%}Mg$ powders mixture and $Al-5wt{\%}Mg/SiCp$ mixture were compacted under a pressure of 350MPa and were bonded by sintering at temperatures ranging from 873K to 1173K for 1-5h. At 873k, the sound bi-mate-rials could not be obtained. In contrast, the bi-materials with the macroscopically well-bonded interface were obtained at higher temperatures than 873K. The length of well-bonded interface became longer with increasing temperature and time, indicating the improved contact in the interface between unreinforced Al-Mg part and Al-Mg/SiCp composite part. The relative density in the bi-materials increased as the sintering temperature and time increased, and the bi-materials sintered at 1173K for 5h showed the highest density.

• Journal of the Korean Institute of Gas
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• v.18 no.6
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• pp.45-50
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• 2014

In this paper, designed the driving part of a straight line precision transfer system which can be applied to industrial machines and industrial robots. The direction of power transfer and the output characteristic are similar to those of the conventional rack-pinion type, but it applied new pin-pinion type to the driving part. As a result, it achieved indefinite expandability in length and secured the convenience of installation. To determine the optimal contact of pin-pinion gear, it conducted a Cycloid tooth profile analysis.

• Steel and Composite Structures
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• v.28 no.5
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• pp.541-557
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• 2018

This paper presents the influence of carbon nanotubes (CNTs) waviness and aspect ratio on the vibrational behavior of functionally graded nanocomposite sandwich annular sector plates resting on two-parameter elastic foundations. The carbon nanotube-reinforced (CNTR) sandwich plate has smooth variation of CNT fraction along the thickness direction. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. Effects of CNT distribution, volume fraction, aspect ratio and waviness, and also effects of Pasternak's elastic foundation coefficients, sandwich plate thickness, face sheets thickness and plate aspect ratio are investigated on the free vibration of the sandwich plates with wavy CNT-reinforced face sheets. The study is carried out based on three-dimensional theory of elasticity and in contrary to two-dimensional theories, such as classical, the first- and the higher-order shear deformation plate theories, this approach does not neglect transverse normal deformations. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1871-1879
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• 2015

The complex roles of flagella in the pathogenesis of Campylobacter jejuni, a major cause of worldwide foodborne diarrheal disease, are important. Compared with the wild-type, an insertional mutation of the flgA gene (cj0769c) demonstrated significant decrease in the biofilm formation of C. jejuni NCTC11168 on major food contact surfaces, such as polystyrene, stainless steel, and borosilicate glass. The flgA mutant was completely devoid of flagella and non-motile whereas the wild-type displayed the full-length flagella and motility. In addition, the biofilm formation of the wild-type was inversely dependent on the viscosity of the media. These results support that flagellar-mediated motility plays a significant role in the biofilm formation of C. jejuni NCTC11168. Moreover, our adhesion assay suggests that it plays an important role during biofilm maturation after initial attachment. Furthermore, C. jejuni NCTC11168 wild-type formed biofilm with a net-like structure of extracellular fiber-like material, but such a structure was significantly reduced in the biofilm of the flgA mutant. It supports that the extracellular fiber-like material may play a significant role in the biofilm formation of C. jejuni. This study demonstrated that flgA is essential for flagellar biosynthesis and motility, and plays a significant role in the biofilm formation of C. jejuni NCTC11168.