• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.1-10
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• 2006

In this paper, a broadband RF module is designed and tested for 2.4GHz band applications. The RF module is composed of a low noise amplifier (LNA) with a three stage amplifier, a single ended gate mixer, matching circuits, a hairpin line band pass filter and a Chebyshev low pass filter to convert the radio frequency (RF) into the intermediate frequency (IF). The LNA has a high gain and stability, and the single ended gate mixer has a high conversion gain and wide dynamic range. In the analysis of the broadband RF module, the composite harmonic balance technique is used to analyze the operating characteristics of an RF module circuit. The RF module has a 55.2dB conversion gain with a 1.54dB low noise figure, $-120{\sim}-60dBm$ wide RF power dynamic range, -60dBm low harmonic spectrum and a good isolation factor among the RF, IF, and local oscillator (LO) ports.

• Earthquakes and Structures
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• v.6 no.1
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• pp.71-87
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• 2014

Interaction between closely-spaced buildings subject to earthquake induced strong ground motions, termed in the literature as "seismic pounding", occurs commonly during major seismic events in contemporary congested urban environments. Seismic pounding is not taken into account by current codes of practice and is rarely considered in practice at the design stage of new buildings constructed "in contact" with existing ones. Thus far, limited research work has been devoted to quantify the influence of slab-to-slab pounding on the inelastic seismic demands at critical locations of structural members in adjacent structures that are not aligned in series. In this respect, this paper considers a typical case study of a "new" reinforced concrete (R/C) EC8-compliant, torsionally sensitive, 7-story corner building constructed within a block, in bi-lateral contact with two existing R/C 5-story structures with same height floors. A non-linear local plasticity numerical model is developed and a series of non-linear time-history analyses is undertaken considering the corner building "in isolation" from the existing ones (no-pounding case), and in combination with the existing ones (pounding case). Numerical results are reported in terms of averages of ratios of peak inelastic rotation demands at all structural elements (beams, columns, shear walls) at each storey. It is shown that seismic pounding reduces on average the inelastic demands of the structural members at the lower floors of the 7-story building. However, the discrepancy in structural response of the entire block due to torsion-induced, bi-directionally seismic pounding is substantial as a result of the complex nonlinear dynamics of the coupled building block system.

• Clinical and Experimental Pediatrics
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• v.58 no.10
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• pp.398-401
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• 2015

Tularemia is a potentially severe zoonotic disease caused by Francisella tularensis. A lack of awareness about tularemia can be embarrassing and could result in delayed treatment because of improper diagnosis. The diagnosis of tularemia is difficult, because the infections are rare and the clinical spectrum is broad. As only 1 adult case has been reported in Korea thus far, pediatricians in Korea may be unfamiliar with tularemia. We report our experience with a 14-year-old male adolescent with tularemia who presented with atypical pneumonia and possible infective endocarditis. Although the infectivity and mortality rates for tularemia are very high if left untreated, we did not suspect tularemia in this case until the incidental isolation of F. tularensis. The present case suggests that clinicians in Korea should be more aware of tularemia. This case also suggests that tularemia should be considered in undetermined cases of atypical pneumonia or acute febrile illness without local signs.

• Journal of Korean Academy of Nursing
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• v.47 no.1
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• pp.14-24
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• 2017

Purpose: The purpose of this study was to construct and test a hypothetical model of self-management in patients with hemodialysis based on the Self-Regulation Model and resource-coping perspective. Methods: Data were collected from 215 adults receiving hemodialysis in 17 local clinics and one tertiary hospital in 2016. The Hemodialysis Self-management Instrument, the Revised Illness Perception Questionnaire, Herth Hope Index and Multidimensional Scale of Perceived Social Support were used. The exogenous variable was social context; the endogenous variables were cognitive illness representation, hope, self-management behavior, and illness outcome. For data analysis, descriptive statistics, Pearson correlation analysis, factor analysis, and structural equation modeling were performed. Results: The hypothetical model with six paths showed a good fitness to the empirical data: GFI=.96, AGFI=.90, CFI=.95, RMSEA=.08, SRMR=.04. The factors that had an influence on self-management behavior were social context (${\beta}=.84$), hope and cognitive illness representation (${\beta}=.37$ and ${\beta}=.27$) explaining 92.4% of the variance. Self-management behavior mediated the relationship between psychosocial coping resources and illness outcome. Conclusion: This research specifies a more complete spectrum of the self-management process. It is important to recognize the array of clinical resources available to support patients' self-management. Healthcare providers can facilitate self-management through collaborative care and understanding the ideas and emotions that each patient has about the illness, and ultimately improve the health outcomes. This framework can be used to guide self-management intervention development and assure effective clinical assessment.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.6
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• pp.18-26
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• 1999

This paper presents the architecture and design of a DSSS MODEM ASIC chip for wireless local area networks (WLAN). The implemented MODEM chip supports the DSSS physical layer specifications of the IEEE 802.11. The chip consits of a transmitter and a receiver which contain a CRC encoder/decoder, a differential encoder/decoder, a frequency offset compensator and a timing recovery circuit. The chip supports various data rates, i.e., 4,2 and 1Mbps and provides both DBPSK and DQPSK for data modulation. We have performed logic synthesis using the $SAMSUNG^{TM}$ $0.6{\mu}m$ gate array library and the implemented chip consists of 53,355 gates. The MODEM chip operates at 44MHz, the package type is 100-pin QFP and the power consumption is 1.2watt at 44MHz. The implemented MODEM architecture shows lower BER compared with the Harris HSP3824.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6A
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• pp.871-880
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• 1999

In this paper, a pseudo-noise(PN) tracking and demodulation circuits are analyzed and designed for a direct-sequence/spread-spectrum multiple access system under a mobile fading channel. We consider noncoherent delay locked loop(DLL) as a PN code tracking loop which has 1/8 PN chip resolution. The tracking performance of DLL is evaluated in terms of locking time from a loose state and tracking jitter. The received signal is demodulated to original data by despreading with PN code locked by DLL. Also the designed circuit supports sound service of 32Kbps and in-band signal with 4.096MHz chip clock. The circuits are implemented and verified with FPGA, which is shown completely data recovery under AWGN 7dB and will be available for IMT-2000.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.53-60
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• 2012

The aim of this study was to explore the spatial and energy resolutions of a PET scanner that we have recently developed. The scanner, which consists of six detector modules with 1-layer LGSO crystals, has a hexagonal configuration with a faceto- face distance of 86.4 mm between two opposite PET modules; such properties facilitate the imaging of small animals. A $^{22}Na$ point source was employed to estimate horizontal and vertical spatial resolutions. To assess the energy resolution, a uniform $^{18}F$ cylindrical phantom was scanned. A software-based spectrum analysis of list-mode data was used to assign a local energy window centered on the photopeak position for every single crystal. For the image reconstruction, an ML-EM algorithm was used. The spatial resolutions at the center of the scanner were 0.99 mm in the horizontal direction and 1.13 mm in the vertical direction. The energy resolution averaged over each PMT ranged from 13.3%-14.3%, which gave an average value of 13.8%. These results show that this simple system is promising for small animal imaging with excellent spatial and energy resolutions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.5
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• pp.19-25
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• 2004

In this paper, we propose optimal and suboptimal serial code acquisition schemes for chip-asynchronous direct-sequence spread-spectrum systems. The conventional serial code acquisition scheme is to compare each value of correlator outputs with a threshold individually. However, such a scheme is optimum only under the chip-synchronous assumption which is actually very difficult to be held prior to acquisition at the receiver because the signal-to-noise ratios before despreading are very low. In this paper, an optimal serial code acquisition scheme is derived based on the maximum-likelihood criterion under the more realistic and general chip-asynchronous environments. A suboptimal scheme, which is simpler but yields comparable performance to the optimal one, is also derived based on the criterion of local detection power Numerical results show that, under the chip-asynchronous environments, both the optimal and suboptimal serial code acquisition schemes outperform the conventional serial code acquisition scheme.

• Earthquakes and Structures
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• v.18 no.1
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• pp.27-44
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• 2020

This work presents a comparison of three performance-based seismic design methods (PBSD) as applied to plane steel frames having eccentric braces (EBFs) and buckling restrained braces (BRBFs). The first method uses equivalent modal damping ratios (ξ_k), referring to an equivalent multi-degree-of-freedom (MDOF) linear system, which retains the mass, the elastic stiffness and responds in the same way as the original non-linear MDOF system. The second method employs modal strength reduction factors (${\bar{q}}_k$) resulting from the corresponding modal damping ratios. Contrary to the behavior factors of code based design methods, both ξ_k and ${\bar{q}}_k$ account for the first few modes of significance and incorporate target deformation metrics like inter-storey drift ratio (IDR) and local ductility as well as structural characteristics like structural natural period, and soil types. Explicit empirical expressions of ξ_k and ${\bar{q}}_k$, recently presented by the present authors elsewhere, are also provided here for reasons of completeness and easy reference. The third method, developed here by the authors, is based on a hybrid force/displacement (HFD) seismic design scheme, since it combines the force-base design (FBD) method with the displacement-based design (DBD) method. According to this method, seismic design is accomplished by using a behavior factor (q_h), empirically expressed in terms of the global ductility of the frame, which takes into account both non-structural and structural deformation metrics. These expressions for q_h are obtained through extensive parametric studies involving non-linear dynamic analysis (NLDA) of 98 frames, subjected to 100 far-fault ground motions that correspond to four soil types of Eurocode 8. Furthermore, these factors can be used in conjunction with an elastic acceleration design spectrum for seismic design purposes. Finally, a comparison among the above three seismic design methods and the Eurocode 8 method is conducted with the aid of non-linear dynamic analyses via representative numerical examples, involving plane steel EBFs and BRBFs.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.61.2-61.2
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• 2011

Low-ionization nuclear emission-line regions (LINERs) have been generally regarded to be powered by active galactic nuclei (AGNs), yet still a number of alternative explanations on the origin of LINER emission are suggested; for example, planetary nebulae nuclei of massive stars, supernovae shocks from death of massive stars, and old stellar populations. Interestingly, a majority of recent star formation early-type galaxies (ETGs) in local universe presents such LINER emission lines. Given that situation, revealing the true nature of LINERs is a crucial step to constrain the evolution path to quiescent ETGs. To resolve the issue, we use Keck/LRIS to obtain spatially resolved spectra on a carefully selected ETG. The ETG SDSS J091628.05+420818.7 at redshift z ~ 0.024 shows modest LINER emission line features without any detection of 21 cm radio continuum nor X-ray emission. We perform a stellar continuum subtraction and measure emission line strengths and their uncertainties for each spectrum from five apertures along the slit with size of 1 arcsecond (~0.5 kpc). We find that extended spatial distributions of four emission lines $H{\alpha}$, $H{\beta}$, [OIII]${\lambda}5007$, and [NII]${\lambda}6583$, and they can be explained by central emission blurring effect. We conclude that the emissions seem to be centrally concentrated, indicating the AGN-nature of LINERs.