• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.2
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• pp.157-161
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• 1994

A 14-year-old male patient was referred to us for evaluation of Right TMJ clicking sound and mandibular deviation during mouth opening. On examinaaation, protrusion and lateral excursion was also restricted. Radiographs showed hook-like curved elongation of Right coronoid process with limitation o right condylar translation. His past medical and dental history was noncontributory. This patient underwent an extraoral coronoidectomy and the specimen revealed coronoid process malformation mimicking condylar head. Microcoically, the specimen discloses mature bony trabeculae. At postoperative 5 days, physical therapy was instituted. At present, this patient could open his mouth well with any clicking sound and mandibular deviation. The asymmetric face of this patient is expectated to be corrected by periodic observation and remained growth porential. If not to be corrected, orthognathic surgery will be done.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.983-990
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• 2003

In this paper, a noncoherent code tracking loop is designed for 3GPP MODEM and its performance is analyzed in terms of steady-state jitter variance and transient response characteristics. An analytical closed-form formula for steady-state jitter variance is Int derived for AWGN environments as a general function of a pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth, together with the analysis on the transient response characteristic of a tracking loop. Based on the analysis, the code tracking loop with variable loop bandwidth that is efficient for full digital H/W implementation is designed and its performance is compared with that of the code tracking loop with fixed loop bandwidth, along with the verification by computer simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.461-475
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• 2006

In this paper, it is described about the tri-band mobile antenna system design to provide broadband multimedia and direct broadcasting services using goo-stationary Koreasat 3, simultaneously operated in Ka/K/Ku band. The radiating part of the antenna system with a fan beam characteristic in the elevation plane is composed of the quasi-offset dual shaped reflector and the tri-band feeder. The tri-band feeder is also composed of the Ka/K dual band feeder with the protruding dielectric rod, the circular polarizer, the ortho-mode transducer and the circular-polarized Ku band feed array. Especially, the Ka/K dual band circular polarizer was realized firstly using the comb-type structure. For fast satellite-tracking on the movement, the Ku band feed array has the structure of the $2{\times}2$ active phased array which can make electrical beams. And, the circular-polarized characteristic in the feed array was improved by $90^{\circ}$ rotating arrangement of four radiating elements polarized circularly by a $90^{\circ}$ hybrid coupler, respectively. Four beam forming channels to make electrical beams at Ku band are divided into the main beam channel and the tracking beam channel in the output, and noise temperature characteristics of each channel were analyzed on the basis of the contributions of internal sub_units. From the fabricated antenna system, the output power at $P_{1dBc}$ of Ka_Tx channel was measured more than 34.1 dBm and the measured noise figures of K/Ku_Rx channels were less than 2.4 dB and 1.5 dB, respectively, over the operating band. The radiation patterns with co- and cross-polarization in the tri-band were measured using a near-field measurement in the anechoic chamber. Especially, Ku radiation patterns were measured after correcting each initial phase of active channels with partial radiation patterns obtained from the independent excitation of each channel. The antenna gains measured in Ka/K/Ku band of the antenna system were more than 39.6 dBi, 37.5 dBi, 29.6 dBi, respectively. And, the antenna system showed good system performances such as Ka_Tx EIRP more than 43.7 dBW and K/Ku_Rx G/T more than 13.2 dB/K and 7.12 dB/K, respectively.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.19 no.2
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• pp.167-180
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• 1997

79 surgically managed mandibular condylar fracture patients included the 25 patients treated with Dr, Nam's method were analysed the postoperative resluts in Oral and Maxillofcial Surgery, School of Dentistry, Wonkwang University since 1993 to 1995. Mean patient's age is 32.5 years (range, 8 to 65 years), and follow-up periods were a minimum of 3 months to 28 months. 19% condylar fractures were associated with mostly symphysis portion. According to the patient's age, severity of condylar fractures, clinical signs and symptoms, radiographic findings, treatmenet plans had been performed. Rigid fixation have performed greatly, and then fragment removal of fractured mesial pole of proximal segment of the condylar and little cases of reshaping and eminoplasty and lag screw have been applied. Two cases of the both condylar resorption and deviated condyle posteriorly in Dr. Nam's method. None of infection or necrosis signs of treated condyle surgically. In my opinion, whenever possible, displaced condylar fracture can be managed surgically with rigid fixation, but not Dr. Nam's method. Usually if perform the surgical management of condylar fractures you should maintain maxillomandibular fixation for 2 weeks, or more and has to follow-up functional mandibular exercise should be kept continuously.

• The Journal of the Acoustical Society of Korea
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• v.10 no.4
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• pp.19-26
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• 1991

$GQ^2PSK$ which is a novel digital mobile communication modulation scheme has been introduced and described. $GQ^2PSK$ is a modulation scheme that bandlimits NRZ digital data with Gaussian filter and modulates it by $Q^2PSK$ scheme which uses two shaping pulses and two carriers which are pairwise quadrature. Thus transmission bit rate can be enhanced and available signal space dimensions are more efficiently utilized, with comparison to the already-existing GMSK, QPSK and OQPSK modulation methods. Via the computer simulation, bit error rate of $GQ^2PSK$ scheme which is bandlimited by gaussian filter to be suitable for digital mobil communication, is lower than that of $Q^2PSK$ by 1.4[dB] in case that the signal-to-noise ration is 0[dB], but we have confirmed that $GQ^2PSK$ modulation scheme is approximately equivalent to the GMSK in the respect of power efficiency, and transmission efficiency of $GQ^2PSK$ is improved to 1.5 times than that of GMSK.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1381-1388
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• 1993

This paper presents a method for the simultaneous optimal design of structural and control systems. Sensitivities of performance index with respect to structural design variables are analyzed. The structural design variables are optimized to minimize the performance index by use of conjugate gradient method. The method is applied to a half model of an active vehicle suspension system with elastic body moving on a randomly profiled road. The suspension control force of an optimally controlled system in the presence of measurement errors are calculated by use of linear quadratic Gaussian control theory and Kalman filter theory. The performance index contains ride comfort, road holding and working space of suspension. The structural design variables taken are stiffness, daming properties and the position of the suspension system. The random road profile considered as colored noise is shaped from white noise by use of shaping filter. The performance of an optimal simultaneous structure/control system is compared with that of an optimal controlled system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.183-192
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• 2000

In this paper, the dual looped CMOS PLL with 3-250MHz input locking range at a single 13.3V is designed. This paper proposed a new PLL architecture with a current pumping algorithm to improve voltage-to-frequencylinearity of VCO(Voltage Controlled Oscillator). The designed VCO operates at a wide frequency range of75.8MHz-lGHz with a high linearity. Also, PFD(Phase frequency Detector) circuit preventing voltage fluctuation of the charge pump with loop filter circuit under the locked condition is designed. The simulation results of the PLL using 0.6 um N-well single poly triple metal CMOS technology illustrate a locking time of 3.5 us, a power dissipation of 92mW at 1GHz operating frequency with 125MHz of input frequency. Measured results show that the phase noise of VCO with V-I converter is -100.3dBc/Hz at a 100kHz offset frequency.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.127-133
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• 2005

Rotary swaging is one of the incremental forming process which is a chipless process using the reduction of cross-sections of bars, tubes and wires. The TDS(Tube Drive Shaft) of monobloc used in automotive has been developed by the rotary swaging process. The mechanical characteristics of swaged parts such as the hardness, thickness and roughness are also estimated to conduct experimental analyses of rotary swaging process with the materials of 34Mn5 Furthermore the change in the vibration mode of TDS due to design parameters, which are the tube length, diameter and thickness, has been investigated and analysed. The weight of the TDS product is smaller by about $12.8\%$ than that of SDS with the same performance. It could be evidently found that the TDS is designed to be much lighter than SDS (Solid Drive Shaft). This advantage might give some possibility to improve the NVH (Noise-Vibration-Harshness) characteristics. A maximum torque and a total number of torsional repetitions for the TDS is checked and measured to know the torsional intensity and fatigue strength through the static torsion test and torsional durability test, respectively. A total number of the torsional repetitions up to the fracture for the TDS is greater than 250,000 times.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.429-438
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• 2004

In this paper, a decision-feedback coherent code tracking loop is designed for WCDMA systems and its performance is analyzed in terms of jitter variance considering the effect of phase and symbol estimation errors for both AWGN and fading environments. An analytical closed-form formula for jitter variance is Int derived for AWGN environments as a function of a pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth while involving the phase estimation error and bit error rate, and the upper bound of jitter variance is derived for fading environments. Finally a second-order coherent code tracking loop is designed with the DPCH frame format #13 of the WCDHA forward link selected as a target system, and its performance is evaluated by the closed-form formula and compared with the simulation results for both AWGN and Rayleigh fading environments.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.3
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• pp.351-355
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• 2000

Penetrating injuries in the head and neck region are not common but can pose difficult situations to manage properly. In small cross-sectional area, the neck housed many vital structures, such as carotid artery, internal jugular vein, cervical spines, esophagus, laryngotracheal complex and nerves. Because each vital structure is located within the fascial compartments, bleeding into these closed spaces can give rise to compression of surrounding structures, which may result in compromised airway. Therefore, management of the penetrating injuries should be based on the fully understanding of anatomical relationships, accurate clinical examinations, a careful history taking and the proper treatment planning. We present two cases of penetrating injuries in the head and neck region and discuss on the clinical considerations for the proper management with the literature review.