• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.263-268
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• 2002

DFDM is a good candidate for beyond-3G high-speed wireless communication application because of the robustness to the intersymbol interference and multipath fading. However. an OFDM signal has a serious problem of the high PAPR, which results in the significant nonlinear distortion when it passes through a nonlinear high power amplifier. We propose a new PAPR reduction method using pre-emphasis and clipping. Via the proposed method, the OFDM output signal can have a low PAPR and BER improvement. Then. de-emphasis process is requisite in OFDM receiver. PAPR is reduced to about 5.7 ㏈ at the CCDF= 10$\^$-3/ when the subcarrier number is 16, QPSK modulation is used. pre-emphasis change point Is 3/9 of the peak amplitude of the IFFT output and clipping level is 11 in the IFFT output amplitude. The required SNR at BER=10$\^$-3/ the proposed system is improved by 2 dB than that of the original OFDM system.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.404-414
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• 2005

In the packet data network systems beyond 3G, the service quality of current users is affected by traffic load due to the packet burstiness. There also exists a hot cell problem, a well-known problem of cellular systems, caused by traffic centraliBation. Hot cell problem is one of the major reasons of degrading system performance because hot cell increases the call drop rate without fully utilization of system resource. Therefore, it is very important to distribute the traffic on the several neighboring cells so that system uses its resource effectively and maintains the quality of service. In this paper, we propose the adaptive handoff algorithms for distributing traffic in the packet data network systems. In addition, we propose a new load estimation method with MAC state diagram suitable for packet data network systems. Through the simulation results, we could find that proposed algorithm is able to improve efficiency of system resource and to assure the service quality of users through traffic distribution.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.46.2-46.2
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• 2017

Atmospheric propagation effects at millimeter wavelengths can significantly alter the phases of radio signals and reduce the coherence time, putting tight constraints on high frequency Very Long Baseline Interferometry (VLBI) observations. In previous works it has been shown that non-dispersive (e.g. tropospheric) effects can be calibrated with the frequency phase transfer (FPT) technique. The coherence time can thus be significantly extended. Ionospheric effects, which can still be significant, remain however uncalibrated after FPT, as well as the instrumental effects. In this work, we implement a further phase transfer between two FPT residuals (i.e. so-called FPT2) to calibrate the ionospheric effects based on their frequency dependence. We show that after FPT2, the coherence time at 3 mm can be further extended beyond 8 hours, and the residual phase errors can be sufficiently canceled by applying the calibration of another source, which can have a large angular separation from the target (> $20{\circ}$). Calibrations for all-sky distributed sources with a few calibrators are also possible after FPT2. One of the strengths and uniqueness of this calibration strategy is the suitability for high frequency all-sky survey observations including very weak sources. We discuss the introduction of a pulse calibration system in the future to calibrate the remaining instrumental effects and allowing the possibility of imaging the source structure at high frequencies with FPT2, where all phases are fully calibrated without involving any sources other than the target itself.

• Journal of the Korean Ceramic Society
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• v.49 no.3
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• pp.216-220
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• 2012

Mullite formation in a porcelain body was promoted extensively by replacing kaolinite with pyrophyllite. Effects of mullite formation and vitrification by substitution of kaolinite with pyrophyllite on the mechanical and thermal properties were investigated. Addition of 45-55% pyrophyllite (pyrophyllite (45-55%)-feldspar (30%)-Gairome clay (20%)) could vitrify the sintered samples (water absorption : 0.05%, bulk density : 2.66g/cc) and improve the flexural strength (122MPa) when fired at $1280^{\circ}C$. Mullite formation was found to be decreased with increasing content of pyrophyllite. On the contrary, beyond 50% of pyrophyllite quartz and cristobalite phases was found to be increased. Thermal expansion coefficient of the samples decreased with increase of mullite phase. In triaxial system of pyrophyllite-feldspar-clay, the mullite formation of the samples with 50% pyrophyllite reaches about 78.7% and thermal expansion coefficient was found to be $5.4{\times}10^{-6}/K$.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.3
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• pp.1-14
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• 2019

The 4th Industrial Revolution, intelligent automobile application technology is evolving beyond the limit of the mobile device to a variety of application software and multi-media collective technology with big data-based AI(artificial intelligence) technology. with the recent commercialization of 5G mobile communication service, artificial intelligent automobile technology, which is a fusion of automobile and IT technology, is evolving into more intelligent automobile service technology, and each multimedia platform service and application developed in such distributed environment is being developed Accordingly, application software technology developed with a single system SoC of a portable terminal device through various service technologies is absolutely required. In this paper, smart device design for ontology design of intelligent automobile open platform enables to design intelligent automobile middleware software design technology such as Android based SVC Codec and real time video and graphics processing that is not expressed in single ASIC application software technology as SoC based application designWe have experimented in smart device environment through researches, and newly designed service functions of various terminal devices provided as open platforms and application solutions in SoC environment and applied standardized interface analysis technique and proved this experiment.

• International Journal of Oral Biology
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• v.34 no.3
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• pp.157-164
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• 2009

We recently described a novel animal model of trigeminal neuropathic pain following compression of the trigeminal ganglion (Ahn et al., 2009). In our present study, we adapted this model using male Sprague-Dawley rats weighing between 250-260 g and then analyzed the behavioral responses of these animals following modified chronic compression of the trigeminal ganglion. Under anesthesia, the rats were mounted onto a stereotaxic frame and a 4% agar solution ($10{\mu}L$) was injected in each case on the dorsal surface of the trigeminal ganglion to achieve compression without causing injury. In the control group, the rats received a sham operation without agar injection. Air-puff, acetone, and heat tests were performed at 3 days before and at 3, 7, 10, 14, 17, 21, 24, 30, 40, 55, and 70 days after surgery. Compression of the trigeminal ganglion produced nociceptive behavior in the trigeminal territory. Mechanical allodynia was established within 3 days and recovered to preoperative levels at approximately 60 days following compression. Mechanical hyperalgesia was also observed at 7 days after compression and persisted until the postoperative day 40. Cold hypersensitivity was established within 3 days after compression and lasted beyond postoperative day 55. In contrast, compression of the trigeminal ganglion did not produce any significant thermal hypersensitivity when compared with the sham operated group. These findings suggest that compression of the trigeminal ganglion without any injury produces prolonged nociceptive behavior and that our rat model is a useful system for further analysis of trigeminal neuralgia.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.267-273
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• 2006

This paper improves the effects of clustered OFCDM scheme considering the frequency diversity effect over a frequency selective fading channel. In OFCDM with frequency domain spreading compared to OFDM, we can increase uncorrelated symbols by frequency allocation method of correspondent symbols over the same antenna and different antenna after spreading. The simulation results show that the performance of proposed system is improved by approximately 4 dB in ${\sigma}=0.02{\mu}sec$, the performance is improved by approximately 2.5dB in large delay spread in a 12-path Rayleigh fading channel with overall the root mean squared delay spread and the maximum Doppler frequency of 20 Hz. Also, the required average received Eb/No at the average BER of $10^{-3}$ by optimum method is improved by approximately 2.0 dB, compared to that of STA-OFCDM with frequency rearrange. The new method does not require any bandwidth expansion any feedback from the receiver to the transmitter and its computation complexity is similar to clustered OFCDM.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.235-243
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• 2012

Objectives: The purpose of this study is the work environment management method through risk assessment and investigation of the work place that deals with Ammonium nitrate, based on information in and outside the country. Methods: This study suggests method of work environment management through risk assessment and investigation of the work place that deals with Ammonium nitrate, and finds out cases of Ammonium nitrate causing hazard, danger and health risk, based on literature investigation. Results: Rats exposed repeatedly to $LD_{50}$ 2,217 mg/kg(rat), $LC_{50}$ 88.8 mg/L(rat, skin) which cause high level of skin irritation, reported 1 $mg/m^3$ of NOAEL, while LOAEL was less than 100 mg/kg for the rats orally administered with the $LD_{50}$ 2,217 mg/kg(rat), $LC_{50}$ 88.8 mg/L(rat, skin), for 13 weeks. Domestically 31,640 ton/y of ammonium nitrate has been used in 22 workplace and the result of workplace assessment was 0.0171-0.9983 $mg/m^3$. ADD was 8.77-59.63 ${\mu}g/kg-day$ according to the exposure scenario. In other words the result of the risk assessment goes beyond the 'standard 1'. Conclusions: Ammonium nitrate creates a high level of irritation and toxicity when coming in breathe it or contact with skin, and is classified as category3 of GHS and specific target organ toxicant (irritating respiratory system). Exposure level at work places needs to be maintained under $1mg/m^3$, to prevent workers from being damaged.

• Geomechanics and Engineering
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• v.35 no.5
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• pp.539-554
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• 2023

This article is dedicated to the pursuit of establishing a robust empirical relationship that allows for the estimation of in-situ modulus of deformations (E_m and G_m) within sedimentary rock slope masses through the utilization of Q_slope values. To achieve this significant objective, an expansive and thorough methodology is employed, encompassing a comprehensive field survey, meticulous sample collection, and rigorous laboratory testing. The study sources a total of 26 specimens from five distinct locations within the South Pars (known as Assalouyeh) region, ensuring a representative dataset for robust correlations. The results of this extensive analysis reveal compelling empirical connections between E_m, geomechanical characteristics of the rock mass, and the calculated Q_slope values. Specifically, these relationships are expressed as follows: E_m = 2.859 Q_slope + 4.628 (R² = 0.554), and G_m = 1.856 Q_slope + 3.008 (R² = 0.524). Moreover, the study unravels intriguing insights into the interplay between in-situ deformation moduli and the widely utilized Rock Mass Rating (RMR) computations, leading to the formulation of equations that facilitate predictions: RMR = 18.12 E_m0.460 (R² = 0.798) and RMR = 22.09 G_m0.460 (R² = 0.766). Beyond these correlations, the study delves into the intricate relationship between RMR and Rock Quality Designation (RQD) with Qslope values. The findings elucidate the following relationships: RMR = 34.05e^0.33Qslope (R² = 0.712) and RQD = 31.42e^0.549Qslope (R² = 0.902). Furthermore, leveraging the insights garnered from this comprehensive analysis, the study offers an empirically derived support system tailored to the distinct characteristics of discontinuous rock slopes, grounded firmly within the framework of the Q_slope methodology. This holistic approach contributes significantly to advancing the understanding of sedimentary rock slope stability and provides valuable tools for informed engineering decisions.

• Journal of Animal Science and Technology
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• v.48 no.1
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• pp.9-14
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• 2006

Milk yield and its quality traits determine the dairy enterprise profitability and sustainability. Milk quality traits including somatic cell counts (SCC) is an upcoming economic challenge for dairy farming community in Korea. This study estimated the effect of parity, stage of lactation (early, mid and late lactation) on SCC, stress (blood cortisol) and immunity (blood IgG, lymphocyte and neutrophil) traits, their heritabilities and genetic correlations between them. SCS and blood neutrophil count were significantly affected by both parity and stage of lactation, however; IgG was affected by only stage of lactation, and blood cortisol and lymphocyte were not affected by both factors. The SCS has shown increasing trend with the parity, however; the difference between first and second parity, second and third parity were not significant. The SCS in early (≤90 days) and late lactation (181≤days) were higher than that of mid lactation (91～180 days). Cortisol concentration in blood was lowest in fourth parity, however; the differences among the first three parties were not significant. The IgG was higher in fourth parity compare with first parity however; all other comparisons were noted non-significant. The IgG concentration was significantly higher in early lactation than those of mid and late lactation. The blood lymphocytes were decreased with increasing parity however the differences beyond second parity were not significant. The neutrophils were increased with the increasing lactation stage however; the difference between early and mid lactation was not significant. Although heritability of SCS was still lower, but it was meaningful value (0.09) and may be considered to improve milk quality. The genetic correlations between SCS and cortisol (-0.96), and lymphocyte (-0.76) were highly negative. Heritability of cortisol was low, however genetic correlations between cortisol and lymphocyte (0.79) was highly positive. IgG with medium heritability was correlated negatively with lymphocyte (-0.88) and neutrophil (-0.98). Lymphocyte was lowly heritable and highly correlated with neutrophil concentration (0.87).This study suggested that cortisol, IgG, lymphocyte and neutrophil being positively genetically correlation with somatic cell score could be used as alternative traits to enhance milk quality in Holstein cattle. Further studies are warranted to estimate genetic relationships between immunological and production traits to increase the genetic merit of Holstein cows for milk yield, to improve animal health and economic viability under intensive management system.