• Smart Structures and Systems
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• v.8 no.1
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• pp.139-155
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• 2011

Polymeric thin-film assemblies whose bulk electrical conductivity and mechanical performance have been enhanced by single-walled carbon nanotubes are proposed for measuring strain and corrosion activity in metallic structural systems. Similar to the dermatological system found in animals, the proposed self-sensing thin-film assembly supports spatial strain and pH sensing via localized changes in electrical conductivity. Specifically, electrical impedance tomography (EIT) is used to create detailed mappings of film conductivity over its complete surface area using electrical measurements taken at the film boundary. While EIT is a powerful means of mapping the sensing skin's spatial response, it requires a data acquisition system capable of taking electrical impedance measurements on a large number of electrodes. A low-cost wireless impedance analyzer is proposed to fully automate EIT data acquisition. The key attribute of the device is a flexible sinusoidal waveform generator capable of generating regulated current signals with frequencies from near-DC to 20 MHz. Furthermore, a multiplexed sensing interface offers 32 addressable channels from which voltage measurements can be made. A wireless interface is included to eliminate the cumbersome wiring often required for data acquisition in a structure. The functionality of the wireless impedance analyzer is illustrated on an experimental setup with the system used for automated acquisition of electrical impedance measurements taken on the boundary of a bio-inspired sensing skin recently proposed for structural health monitoring.

• Journal of the Korean Arthroscopy Society
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• v.2 no.1
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• pp.45-50
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• 1998

Recently, a variety of arthroscopic techniques have been reported for the treatment of the displaced tibial eminence fracture. The purpose of this study was to describe details of arthroscopic technique using pull-out wire and to evaluate the results. Eleven patients with irreducible type II and type III tibial eminence fractures underwent the arthroscopic reduction and internal fixation using double strand pull-out wiring. The anterior cruciate ligament tibial drill guide was utilized for the reduction of fracture and passage of the guide pins. The tibial eminence fracture was firmly fixed with double strand 26-gauge pull-out wire(0.45mm diameter). Fracture union was achieved at 7.2 weeks (range, six to eight weeks) after operation. All cases were united at the last follow-up. Subjectively, nine patients had no pain and no restriction of daily activities. Two patients with combined injuries had limitation of knee motion(10 to 130 degrees, respectively) and one patient showed mild anterior laxity. Early rehabilitation was enabled without loss of reduction and breakage of pull-out wire. The arthroscopic reduction and internal fixation using pull-out wire showed good results including early rehabilitation, early fracture union, minimal morbidity, and no requirement of the second operation for hard ware removal.

• Journal of Korean Neurosurgical Society
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• v.42 no.3
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• pp.168-172
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• 2007

Objective : Hirabayashi's open-door laminoplasty is a good procedure to use to treat patients with myelopathy of the cervical spine; however, the authors have experienced problems in maintaining an open-window in cervical spines after the surgery. The authors developed a modified method of the expanded open-door laminoplasty and compared the radiological and clinical results with those of the classical method. Methods : In the modified method, wiring fixation with lateral mass screws on the contra lateral-side instead of fixing the paraspinal muscle or facet joint, as in the classical methods, was used in the open window of the cervical spine. Fifteen patients with cervical myelopathy were treated using the classical method and 12 patients were treated using the modified method. Preoperative and postoperative clinical conditions were assessed according to the Japanese Orthopedic Association (JOA) score. The radiological results were compared with the preoperative and postoperative computed tomography (CT) findings. Results : In both methods, the clinical results revealed a significant improvement in neurological function (p<0.001). Image analysis revealed that the cervical canals were continuously expanded in patients treated using the modified methods. However, authors have observed restenosis during the follow-up periods in 4 patients treated using the original method. Progression to deformity and spinal instability were not observed in any of the patients in the radiological results. Conclusion : Although analysis with a larger population and a longer follow-up period needs to be undertaken, our modified open-door laminoplasty has shown an advantage in better maintaining an open window in comparison with the Hirabayashi's open-door laminoplasty.

• Journal of Korean Neurosurgical Society
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• v.45 no.3
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• pp.164-168
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• 2009

Objective : Bilateral C1-2 transarticular screw fixation (TAF) with interspinous wiring has been the best treatment for atlantoaxial instability (AAI). However, several factors may disturb satisfactory placement of bilateral screws. This study evaluates the usefulness of unilateral TAF when bilateral TAF is not available. Methods : Between January 2003 and December 2007, TAF was performed in 54 patients with AAI. Preoperative studies including cervical x-ray, three dimensional computed tomogram, CT angiogram, and magnetic resonance image were checked. The atlanto-dental interval (ADI) was measured in preoperative period, immediate postoperatively, and postoperative 1, 3 and 6 months. Results : Unilateral TAF was performed in 27 patients (50%). The causes of unilateral TAF were anomalous course of vertebral artery in 20 patients (74%), severe degenerative arthritis in 3 (11%), fracture of C1 in 2, hemangioblastoma in one, and screw malposition in one. The mean ADI in unilateral group was measured as 2.63 mm in immediate postoperatively, 2.61 mm in 1 month, 2.64 mm in 3 months and 2.61 mm in 6 months postoperatively. The mean ADI of bilateral group was also measured as following; 2.76 mm in immediate postoperative, 2.71 mm in 1 month, 2.73 mm in 3 months, 2.73 mm in 6 months postoperatively. Comparison of ADI measurement showed no significant difference in both groups, and moreover fusion rate was 100% in bilateral and 96.3% in unilateral group (p=0.317). Conclusion : Even though bilateral TAF is best option for AAI in biomechanical perspectives, unilateral screw fixation also can be a useful alternative in otherwise dangerous or infeasible cases through bilateral screw placement.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.292-299
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• 2013

In this paper, we developed a data transmission system over coaxial cable based on the IEEE 802.15.3 MAC and Ultra-Wideband(UWB) Physical Layer. This system is capable of operation in both wireless and wired medias. When operating on coax cable it is capable of Gigabit bi-directional data rate operation on in-home coax wiring and over Hybrid-Fiber-Coax(HFC) cable infrastructure. The developed system transceives command, control and data over a 75 ohm coax system in a home or office. This system operates at a center frequency of 4GHz with a total occupied bandwidth of 1.33Ghz centered on 4GHz. The system uses BPSK modulation and sends symbols at a maximum power level of +15dBm. It has been tested and works through up to three CATV RF splitters in a home environment.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.4
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• pp.79-83
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• 2012

LTCC (Low temperature co-fired ceramic) package have been paid much attention due its good reliability, miniaturization, and application of silver paste with complex wiring and printing. Therefore, LTCC package has been expected to replace vulnerable plastic package in the field of high power LED device. Currently, LTCC ceramic package is mainly made up of aluminum oxide powder. In this study, zinc oxide powder is added or replaced for the fabrication of LTCC ceramic body. By adding small amount of ZnO, thermal conductivity of the LTCC ceramic body could be remarkably increased by 25% leading to the extension of LED life time. The LTCC package structure with composition including ZnO has an increased thermal flux by 56% as a result of ANSYS simulation. Actually, the fabricated LED package with the addition of ZnO exhibits a decreased thermal resistivity by 14.9%.

• Corrosion Science and Technology
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• v.14 no.4
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• pp.177-183
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• 2015

Prestressed Concrete steel Cylinder Pipe (PCCP) is extensively used as seawater pipes for cooling in nuclear power plants. The internal surface of PCCP is exposed to seawater, while the external surface is in direct contact with underground soil. Therefore, materials and strategies that would reduce the corrosion of its cylindrical steel body and external steel wiring need to be employed. To prevent against the failure of PCCP, operators provided a cathodic protection to the pre-stressing wires. The efficiency of cathodic protection is governed by the anodic performance of the system. A mixed metal oxide (MMO) electrode was developed to meet criteria of low over potential and high corrosion resistance. Increasing coating cycles improved the performance of the anode, but cycling should be minimized due to high materials cost. In this work, the effects of $RuCl_3$ concentration on the electrochemical properties and lifespan of MMO anode were evaluated. With increasing concentration of $RuCl_3$, the oxygen evolution potential lowered and polarization resistance were also reduced but demonstrated an increase in passive current density and oxygen evolution current density. To improve the electrochemical properties of the MMO anode, $RuCl_3$ concentration was increased. As a result, the number of required coating cycles were reduced substantially and the MMO anode achieved an excellent lifespan of over 80 years. Thus, we concluded that the relationship between $RuCl_3$ concentration and coating cycles can be summarized as follows: No. of coating cycle = 0.48*[$RuCl_3$ concentration, $M]^{-0.97}$.

• KIEAE Journal
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• v.8 no.4
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• pp.63-69
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• 2008

The thesis is a comparative analysis of Infill Technologies between Korea's long-life Mock-up House, a study driven by 'Durability and Flexibility of Long-life Housing Technology Development' of R&D, and Japan's KSI experimental house, the major example of Japan's long-llfe housing. In terms of the domestic Mock-up House, a system of building the floor first was applied. The floor material of each housing unit required a development of dry heating component that is partially substitutable in order to avoid conflict with the finishing. Also, a development of a floor system that can counteract against the construction inaccuracy was required. In the Case of an outer wall, need to make the wall with the chassis. In the case of ceiling, need to develop the double ceiling system which is good for sound insulation. Also, in comparison to KSI experimental house in Japan, it would require to develop a wiring system of the ceiling which can react to the movement of the wall. Especially, to assure the flexible nature of an internal wall, it would desperately require the research and development of the products related to components and flexible system of mechanical/electrical/communication parts as well as supporting institutionalized system for this development. Furthermore, for KSI experimental house in Japan, it would be necessary to formulate a construction manual as well as a systematic and practical planning guide to invent a new interface rule which will secure simplicity of assembling, dismantling, installation and replacement of architectural components for which research development is quite insignificant at the moment. This effort will have to continue to give a solid direction for better application of such reference manual during construction and development of long life span apartment by public sector as well as private corporations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8C
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• pp.782-791
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• 2002

This paper discusses a far-end crosstalk (FEXT) canceller for twisted-pair transmission. Many twisted-pair systems such as fiber-to-the-curb (FTTC), very high-speed digital subscriber line (VDSL), and high-speed LAN systems, use frequency-division duplexing (FDD) for duplex transmission. It is shown that the maximum reach of FDD twisted-pair system is limited by the performance of its upstream channel, which is located at higher frequencies than the downstream channel. In order to improve the performance of such FDD transceiver, FEXT cancellation is introduced for the channel at higher frequencies. A system arrangement and its blind start-up procedure are studied when the FEXT canceller and equalizer are jointly adapted to combat channel intersymbol interference (ISI), FEXT, and other additive noise. The initial convergence and the steady-state behavior of the proposed twisted-pair system without requiring transmission of an ideal training sequence are investigated. Measured characteristics as well as analytical model of the FEXT channel are used to estimate the time span needed for the FEXT canceller. It is also shown that the memory span for the FEXT canceller is almost independent of the channel, thus making our results useful for the twisted-pair system over all different channels.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.138-143
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• 1999

Recently, miniaturization of large scale integrated circuits (LSI) and printed circuit board (PCB) have become essential with the downsizing of electronic devices. Gold electroplating is applied of conductivity wiring or terminals for improvement of conductivity and corrosion resistance. However, electroplating is not applicable since the circuits are becoming finer and denser. Accordingly, electroless plating is recently highly attractive method because of the simplicity of the operation requiring no external source of current and no elaborate equipment. In this work, we tried to develop a plating technique on electroless Ni/Au plating. First, the electroless Ni plating was deposited on the PCB with agitation in the bath at $85^{\circ}C$. Then the Au layer was deposited on the Ni layer surface by same method at $90^{\circ}C$. The bonderability were tested in order to evaluate the stability of the electroless Ni/Au by gold wire or solder ball test.