• ETRI Journal
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• v.37 no.1
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• pp.32-42
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• 2015

Orthogonal frequency-division multiplexing (OFDM) suffers from spectral nulls of frequency-selective fading channels. Linear precoded (LP-) OFDM is an effective method that guarantees symbol detectability by spreading the frequency-domain symbols over the whole spectrum. This paper proposes a computationally efficient and low-cost implementation for discrete Hartley transform (DHT) precoded OFDM systems. Compared to conventional DHT-OFDM systems, at the transmitter, both the DHT and the inverse discrete Fourier transform are replaced by a one-level butterfly structure that involves only one addition per symbol to generate the time-domain DHT-OFDM signal. At the receiver, only the DHT is required to recover the distorted signal with a single-tap equalizer in contrast to both the DHT and the DFT in the conventional DHT-OFDM. Theoretical analysis of DHT-OFDM with linear equalizers is presented and confirmed by numerical simulation. It is shown that the proposed DHT-OFDM system achieves similar performance when compared to other LP-OFDMs but exhibits a lower implementation complexity and peak-to-average power ratio.

• The Korean Journal of Emergency Medical Services
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• v.17 no.2
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• pp.21-28
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• 2013

Purpose : The aim of the study is to compare the effect of cardiopulmonary resuscitation (CPR) with voice and CPR without voice by one rescuer. Methods : Subjects were 26 students in C University who had basic life support certificate for Healthcare Provider. They performed 30:2 CPR for 6 minutes by two groups of CPR with voice and CPR without voice by one rescuer from August 14 to 16, 2012. They performed CPR with Resusci Anne SkillReporter$^{TM}$ and Laerdal PC SkillReporting System Ver. 2.4.1(Laerdal Medical, Norway and recored voice using TES-1350A(TES Electrical Electronic Corp, Taiwan). Between each experiment, 1 day of rest was given, providing enough time to recover from the fatigue of CPR. Results : The depth, rate of chest compression, and ventilation volume were not affected by a voice (p >.05), and the ratio of chest compression to ventilation kept 30:2, when the subject made a sound (p <.05). Conclusion : Making voice during CPR was associated with an accurate ratio of 30:2 and the reduction in hands off time.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.56.1-56.1
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• 2017

When turbulent motions perturb magnetic field lines and produce magnetic fluctuations, the perturbations leave imprints of turbulence statistics on magnetic field. Observation of synchrotron radiation is one of the easiest ways to study turbulent magnetic field. Therefore, we study statistical properties of synchrotron polarization emitted from media with magnetohydrodynamic (MHD) turbulence, using both synthetic and MHD turbulence simulation data. First, we obtain the spatial spectrum and its derivative with respect to wavelength of synchrotron polarization arising from both synchrotron radiation and Faraday rotation. The study of spatial spectrum shows how the spectrum is affected by Faraday rotation and how we can recover the statistics of underlying turbulent magnetic field as well as turbulent density of electrons from interferometric observations that incorporate the effects of noise and finite telescopic beam size. Second, we study quadrupole ratio to quantitatively describe the degree of anisotropy introduced by magnetic field in the presence of MHD turbulence. We consider the case that the synchrotron emission and Faraday rotation are spatially separated, as well as the situation that the sources of the synchrotron radiation and thermal electrons causing Faraday rotation exist in the same region. In this study, we demonstrate that the spectrum and quadrupole ratio of synchrotron polarization can be very informative tools to get detailed information about the statistical properties of MHD turbulence from radio observations of diffuse synchrotron polarization.

• Journal of Information Processing Systems
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• v.12 no.3
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• pp.525-537
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• 2016

Data hiding is a wide field that is helpful to secure network communications. It is common that many data hiding researchers consider improving and increasing many aspects such as capacity, stego file quality, or robustness. In this paper, we use an audio file as a cover and propose a reversible steganographic method that is modifying the sample values using modulus function in order to make the reminder of that particular value to be same as the secret bit that is needed to be embedded. In addition, we use a location map that locates these modified sample values. This is because in reversible data hiding it needs to exactly recover both the secret message and the original audio file from that stego file. The experimental results show that, this method (measured by correlation algorithm) is able to retrieve exactly the same secret message and audio file. Moreover, it has made a significant improvement in terms of the following: the capacity since each sample value is carrying a secret bit. The quality measured by peak signal-to-noise ratio (PSNR), signal-to-noise ratio (SNR), Pearson correlation coefficient (PCC), and Similarity Index Modulation (SIM). All of them have proven that the quality of the stego audio is relatively high.

• Korean Institute of Interior Design Journal
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• v.24 no.5
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• pp.3-11
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• 2015

The human instinct toward nature is biophilia as a psychological term. There have been a number of empirical evidences confirmed that natural features in buildings enhance human's comfort focusing on biophilia. However, the evolution of society, science, and industry has separated modern buildings from nature. Therefore, this paper addresses the assumption that the admiration for historical buildings in contemporary society is attribute to the qualities of biophilic design. Prospect and refuge, one of the strategies for biophilic design, ultimately provides the opportunity to recover from stress and tension. The purpose of this study is to figure out elements of prospect and refuge based on the design theory of biophilia for psychological healing. This study explores the Gyeongbokgung Palace with the design elements of prospect and refuge in biophilia. It also measures these elements quantitatively with the contrast using Adobe Photoshop CS6, and the area ratio of prospect and refuge. The results of this research verify that the conflicting characteristics of prospect and refuge are identified simultaneously, it is significant to attract people. Gangnyeongjeon Hall and Gyotaejeon Hall, the living quarters for the king and queen, propose the intense pattern of refuge characteristics more than other areas. The mathematical properties of the area ratio show that the pattern of prospect-refuge characteristics change in particular design elements.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.1
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• pp.1969-1974
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• 2020

Background: Early rehabilitation after partial meniscectomy is important to recover the balance of the vastus medialis oblique and vastus lateralis and prevent pathological problems in the lower extremities and the whole body. Objective: To compare muscle activations for patients after partial meniscectomy. Design: Dual-group Pretest-Posttest Design from the Quasi-Experimental Research. Methods: Twenty participants after partial meniscectomy were recruited and were randomly divided into a Q-setting sensorimotor training group (QSMTG) and Q-setting exercise group (QSEG). Muscle activity of the vastus medialis oblique and vastus lateralis was measured before and after intervention. Results: In the two groups, the vastus medialis oblique and vastus lateralis activations increased significantly (P<.05). The Q-setting sensorimotor training group showed more increases than the Q-setting exercise group, and there were significant differences between the groups (P<.05). The activation ratio of the vastus medialis oblique and vastus lateralis had increasingly significant differences in the Q-setting sensorimotor training group (P<.05), and there were no significant differences between the groups (P>.05). Conclusion: Q-setting exercise with sensorimotor training was a useful method that improved the balance of vastus medialis oblique (VMO) and vastus lateralis (VL) activity after meniscectomy.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.1
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• pp.1-14
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• 2023

Underwater images carry information that is useful in the fields of aquaculture, underwater military security, navigation, transportation, and so on. In this research, we transmitted an underwater image through various underwater mediums in the presence of underwater turbulence and beam attenuation effects using a high-speed visible optical carrier signal. The optical beam undergoes scintillation because of the turbulence and attenuation effects; therefore, distorted images were observed at the receiver end. To understand the behavior of the communication media, we obtained the bit error rate (BER) performance of the system with respect to the average signal-to-noise ratio (SNR). Also, the structural similarity index (SSI) and peak SNR (PSNR) metrics of the received image were evaluated. Based on the received images, we employed suitable nonlinear filters to recover the distorted images and enhance them further. The BER, SSI, and PSNR metrics of the specific nonlinear filters were also evaluated and compared with the unfiltered metrics. These metrics were evaluated using the on-off keying and binary phase-shift keying modulation techniques for the 50-m and 100-m links for beam attenuation resulting from pure seawater, clear ocean water, and coastal ocean water mediums.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.682-689
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• 2015

A two-step process was investigated for pretreatment and fractionation of rice straw. The two-step fractionation process involves first, soaking rice straw in aqueous ammonia (SAA) in a batch reactor to recover lignin-rich hydrolysate. This is followed by a second-step treatment in a fixed-bed flow-through column reactor to recover xylo-oligomer-rich hydrolysate. The remaining glucan-rich solid cake is then subjected to an enzymatic process. In the first variant, SAA treatment in the first step dissolves lignin at moderate temperature (60 and $80^{\circ}C$), while in the second step, hot-water treatment is used for xylan removal at higher temperatures ($150{\sim}210^{\circ}C$). Under optimal conditions ($190^{\circ}C$ reaction temperature, 30 min reaction time, 5.0 ml/min flow rate, and 2.3 MPa reaction pressure), the SAA-hot-water fractionation removed 79.2% of the lignin and 63.4% of the xylan. In the second variant, SAA was followed by treatment with dilute sulfuric acid. With this process, optimal treatment conditions for effective fractionation of xylo-oligomer were found to be $80^{\circ}C$, 12 h reaction time, solid-to-liquid ratio of 1:12 in the first step; and 5.0 ml $H_2SO_4/min$, $170^{\circ}C$, and 2.3 MPa in the second step. After this two-step fractionation process, 85.4% lignin removal and 78.9% xylan removal (26.8% xylan recovery) were achieved. Use of the optimized second variant of the two-step fractionation process (SAA and $H_2SO_4$) resulted in enhanced enzymatic digestibility of the treated solid (99% glucan digestibility) with 15 FPU (filter paper unit) of CTec2 (cellulase)/g-glucan of enzyme loading, which was higher than 92% in the two-step fractionation process (SAA and hot-water).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.9
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• pp.937-944
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• 2012

The thermodynamic characteristics of a trilateral cycle with water as a working fluid have been theoretically investigated for an electric generation system to recover the waste heat of the exhaust gas from a diesel engine used for the propulsion of a large ship. As a result, when a heat source was given, the efficiencies of energy and exergy were maximized by the specific conditions of the pressure and mass flow rate for the working fluid at the turbine(expander) inlet. In this case, as the condensation temperature increased, the volume expansion ratio of the turbine could be reduced properly; however, the exergy loss of the heat source and exergy destruction of the condenser increased. Therefore, in order to recover the waste exergy from the topping cycle, the combined cycle with a bottoming cycle such as an organic Rankine cycle, which is utilized at relatively low temperatures, was found to be useful.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.2
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• pp.84-89
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• 2002

In this paper, we present the design method of noise reduction circuit in telephonic system. The circuit consists of compressor, expander and a filter. The basic idea of a proposed method compresses the audible signal in order to mask the channel noise during transmission and then expand at the reverse rate the transmitted signal to naturally recover the original signal. Of course, there should be no distortion or other degradation of the audio itself in passing through companding(compress/expand) cycle. In the compressing process, the gain of compressor is automatically controlled by the envelope level of input signal in order to increase the effective dynamic range of input signal and to improve the signal to noise ratio. The compressed rate is the root time of a audible signal. The compressed signal should be expanded at the square time of the signal to recover a original signal. Simulation shows the proposed method improves the performance of the noise reduction of a channel noise as well as stability.