• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.77-80
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• 2008

Purpose: The majority of nasal fractures have been treated by closed reduction. And they were manipulated under local anesthesia or general anesthesia. Under the local anesthesia, patients can feel the pain and fear, so general anesthesia through the endotracheal intubation became popularized recently to treat the nasal fracture. But it has still the drawbacks of postanesthetic complication. Therefore, under the mask ventilation anesthesia using oral airway, we tried to manipulate the nasal fracture. Methods: From July 2007 to November 2007, we worked with fifty patients that were manipulated the nasal fracture. Fifty patients were divided into two groups, general anesthesia with the endotracheal intubation group(n=25) and the mask ventilation using oral airway group(n=25). We checked up the anesthesia time, postanesthetic complication, postoperative aesthetic & functional problem of nose in two groups. Results: In total operation time and sore throat frequency among the postoperative anesthetic complications, there was statistically significant difference between the mask ventilation group and the endotracheal intubation group(p<0.05). But there was no difference statistically in nausea frequency(p>0.05). And no patients complained of postoperative nasal complication such as septal deviation, septal perforation, nasal obstruction and hump nose in two groups. Conclusion: Through the mask ventilation using oral airway, we could reach satisfactory results in the anesthetic time and postanesthetic complication.

• The KIPS Transactions:PartC
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• v.12C no.7 s.103
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• pp.965-972
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• 2005

Digital documents have become the mainstay of the paperless office. This is due to the increased usage of computer networks and the widespread digital culture. Along with the increased usage of digital documents comes the problem of securing them. The documents nay have very important information such as confidential business policies and intellectual Property statements. Generally, most of users protect them by using a password or secured flash memory or security software, but it has several weaknesses. Accordingly, we propose a new architecture for securing digital documents. The proposed architecture bases on RFID and several encrypting techniques. It makes up for the weakness of traditional securing architectures, and supports various Policies for digital documents of users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1169-1178
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• 1999

In this paper, the method to improve audio noise when GMS(Global System of Mobile Communication) is built in HPC(Handheld PC)is provided. The biggest problem with quality of audio is improved by connecting GSM module with wire to the widest erea near by HPC Power Ground to reduce impedance difference, and designing amplifier and earpiece, Result of measurement is satisfied with GSM Acoustic Standard. Standard of GSM Audio is declared in GSM 11.10 ETS 300 607-1. Measuring items corresponds to that standard and B&K Type 6712 is used for measurement. The list of measurement presented in this paper is Sending Sensitivity Frequency Response and SLR, Sending Loudness Rating( SLR level), Receiving Sensitivity Loudness Rating(RLR level), Talker Sidetone(STMR), Stability margin, and Echo Loss(ERL)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8A
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• pp.583-591
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• 2009

OFDM(orthogonal frequency division multiplexing) signal with high PAPR(peak to average power ratio) produces the nonlinear distortion and/or decreases down the power efficiency of HPA(high power amplifier). So, the IMD(inter-modulation distortion) reduction method was proposed to reduce the nonlinear distortion, which shows better BER(bit error rate) performance than the PAPR reduction methods. However, IMD reduction method has inherent problem which system complexity and processing time increases because the FFT(fast Fourier transform) processor is added in transmitter and decision criterion of IMD reduction method is computed in frequency domain,. In this paper, therefore, we propose a new IMD reduction method to reduce the computational complexity and structure of IMD computation. And we apply this proposed method into OFDM system using PTS(partial transmit sequence) scheme and compare the computational complexity between conventional and proposed IMD reduction method. This method can reduce the system size and computational complexity. Also, the proposed has almost same BER performance with the conventional IMD reduction method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.776-785
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• 2008

Compared with the existing cellular base station whose radio parameters are configured manually, the small base station named as self-configurable base station configures its radio parameters automatically by the central controller. When installing the self-configurable base station, it should be considered primarily that the seamless coverage for the target area is secured while the signal interference to the existing cellular service area must to be minimized. In order to achieve this, it is very important to select the correct radio parameters, e.g., transmission power and working frequency. In this work, we formulate and solve the optimization problem by using mixed integer programming to optimize the air parameter for the self-configurable base stations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.16-23
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• 2010

This paper presents 6bit 250MS/s flash A/D converter which can be applied to wireless communication system. To solve the problem of large power consumption in flash A/D converter, control algorithm by input signal level is used in comparator stage. Also, input voltage range detector circuit is used in reference resistor array to minimize the dynamic power consumption in the comparator. Compared with the conventional A/D converter, the proposed A/D converter shows 4.3% increase of power consumption in analog and a seventh power consumption in digital, which leads to a half of power consumption in total. The A/D converter is implemented in a $0.18{\mu}m$ CMOS 1-poly 6-metal technology. The measured results show 106mW power dissipation with 1.8V supply voltage. It shows 4.1bit ENOB at sampling frequency 250MHz and 30.27MHz input frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.995-1002
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• 2005

An orthogonal frequency division multiplexing(OFDM) system has the problem of the peak-to-average power ratio(PAR). In general, in order to obtain optimal PAR reduction using the partial transmitted sequence(PTS), the total search for the number of sub-blocks and the rotation factors must be accomplished. As the number of sub-blocks and rotation factors increases, PAR reduction improves, such that complexity increases exponentially and the process delay occurs simultaneously. Therefore a technique that reduces PAR, which is almost close to optimal, and the amount of calculation is desired. In this paper a new method using genetic algorithm(GA), which is widely used to search for a point that is globally optimal in many problems, is proposed to search for a rotation factor that reduces simultaneously both the PAR and the amount of calculation, such that the complexity of calculation and the process time are reduced at the same time, Comparison is performed between the proposed method and the various techniques developed previously. The superiority of proposed method is presented by demonstrating the reduction of complexity while a similar PAR reduction is obtained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.497-503
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• 2016

In this study, we formulate an acoustical topology optimization problem to optimally design a partition layout inside the expansion chamber of a muffler. The lower-limit insertion loss value at a target frequency is constrained, and the partition volume is selected as an object function. In this study, we calculate the insertion loss outside the duct, while to determine the noise-attenuation performance, we use the insertion loss value calculated inside the duct or transmission loss value obtained in a previous study. We employ the finite-element model for acoustical analysis, and we determine the transmission of an incident acoustic wave through each finite element using the functions of design variables that change continuously between "0" and "1." The rigid body elements, which totally reflect incident waves, build up partitions. Finally, we compare optimal topologies that depend on the target frequency and the allowed lower-limit value of insertion loss.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.483-488
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• 2016

Plug-In Digital Framework is a system response analysis tool that is employed when system components are composed of black-box modules. Generally, the dynamic characteristics of joints between the system components significantly affect system responses, and they lead to displacement- and frequency-dependent stiffness and loss factor. Thus, the sensitivity of each joint parameters should be estimated from a global perspective. In this study, we introduce a global sensitivity analysis procedure under the Plug-In Digital Framework. To efficiently calculate the system responses, we introduce the frequency response function (FRF)-based substructuring method. Using the random balance designs (RBD), we generate the system responses and estimate the global first-order sensitivities for each joint stiffness. We apply the proposed global sensitivity analysis method to an interior noise problem of a passenger car, and we evaluate the efficiency of the global sensitivity analysis method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.739-744
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• 2012

The genetic algorithm (GA) is regarded as one of the best ways for determining a global solution. Because it does not require calculating the design sensitivity differently from the ordinary gradient-based method, it is appropriate for the design problem in the ultra-high frequency range; the ordinary gradient-based method has difficulty in calculating the sensitivity in this range. This paper deals with nano-aperture grating topology optimization based on the GA and the ON/OFF method. The objective of this study is to maximize the transmittance in the measuring area. The simulation and optimization processes are carried out by using the commercial package COMSOL associated with Matlab programming. The final optimal design gives around 21% performance improvement, compared with the initial model.