• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.26-29
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• 2012

In this paper, we propose a Single Carrier Frequency Division Multiple Access(SC-FDMA) scheme with greatly enhanced tolerance of timing offset among the users. The type of the proposed scheme is similar to code spread Multiple Carrier Direct Spread Code Division Multiple Access(MC DS CDMA). The proposed scheme performs partial Discrete Fourier Transform(DFT) in order to solve high Peak to Average Power Ratio(PAPR) of the MC DS CDMA before Inverse Fast Fourier Transform(IFFT). Exploiting the property Properly Scrambled Walsh-Hadamard(PSW) code has zero correlation despite ${\pm}1$ chip timing offset, the proposed scheme achieves Multiple Access Interference free performance with the timing offset up to ${\pm}1$ OFDM symbol duration with low PAPR. In contrast, the other existing schemes in comparison undergo severe performance degradation even with small timing offset in multipath fading channel.

• Journal of the Korean earth science society
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• v.23 no.1
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• pp.87-96
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• 2002

Aeromagnetic and gravity data were analyzed to delineate the subsurface structure of the Yeongdong basin and its related fault movement in the Okcheon fold belt. The aeromagnetic data of the total intensity (KIGAM, 1983) were reduced to the pole and three dimensional inverse modeling, which considers topography of the survey area in the modeling process, were carried out. The apparent susceptibility map obtained by three dimensional magnetic inversion, as well as the observed aeromagnetic anomaly itself, show clearly the gross structural trend of the Yeongdong basin in the direction on between $N30^{\circ}E$ and $N45^{\circ}E$. Gravity survey was carried out along the profile, of which the length is about 18.2 km across the basin. Maximum relative Bouguer anomaly is about 7 mgals. Both forward and inverse modeling were also carried out for gravity analysis. The magnetic and gravity results show that the Yeongdong basin is developed by the force which had created the NE-SW trending the magnetic anomalies. The susceptibility contrast around Yeongdong fault is apparent, and the southeastern boundary of the basin is clearly defined. The basement depth of the basin appears to be about 1.1 km beneath the sea level, and the width of the basin is estimated to be 7 km based on the simultaneous analysis of gravity and magnetic profiles. There exists an unconformity between the sedimentary rocks and the gneiss at the southeastern boundary, which is the Yeongdong fault, and granodiorite is intruded at the northwestern boundary of the basin. Our results of gravity and magnetic data analysis support that the Yeongdong basin is a pull-apart basin formed by the left-stepping sinistral strike-slip fault, which formed the Okcheon fold belt.

• Journal of Radiation Protection and Research
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• v.42 no.4
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• pp.212-221
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• 2017

Background: This study aims to calculate detector positions as a design of a radioactive source localizing radiation portal monitor (RPM) system using an improved genetic algorithm. Materials and Methods: To calculate of detector positions for a source localizing RPM system optimization problem is defined. To solve the problem, a modified iterative genetic algorithm (MIGA) is developed. In general, a genetic algorithm (GA) finds a globally optimal solution with a high probability, but it is not perfect at all times. To increase the probability to find globally optimal solution rather, a MIGA is designed by supplementing the iteration, competition, and verification with GA. For an optimization problem that is defined to find detector positions that maximizes differences of detector signals, a localization method is derived by modifying the inverse radiation transport model, and realistic parameter information is suggested. Results and Discussion: To compare the MIGA and GA, both algorithms are implemented in a MATLAB environment. The performance of the GA and MIGA and that of the procedures supplemented in the MIGA are analyzed by computer simulations. The results show that the iteration, competition, and verification procedures help to search for globally optimal solutions. Further, the MIGA is more robust against falling into local minima and finds a more reliably optimal result than the GA. Conclusion: The positions of the detectors on an RPM for radioactive source localization are optimized using the MIGA. To increase the contrast of the measurements from each detector, a relationship between the source and the detectors is derived by modifying the inverse transport model. Realistic parameters are utilized for accurate simulations. Furthermore, the MIGA is developed to achieve a reliable solution. By utilizing results of this study, an RPM for radioactive source localization has been designed and will be fabricated soon.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1324-1333
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• 2010

This paper is used in a recent civil engineering field in three-dimensional laser-meter tiles using thermal imaging cameras for the weathered rock slopes precisely measured indirectly, to the degree that began in the will. In the field is difficult to access the degree of weathering of the rock slope to the existing direct way to compensate for the shortcomings of 3D Terrestrial Laser Scanner and weathering characteristics of rocks using thermal imaging cameras to get the information to analyze the degree of rock weathering is. Intensity of 3D TLS and the thermal camera with image analysis to analyze the degree of weathering of bedrock in the field of core drilling targeting indoor laboratory tests were analyzed through the study. Granite, gneiss, sandstone, much of the cancerous samples, each experiment has a 40 per category, each of which 30 were used to analyze the data collected. That degree of rock weathering, the rock, depending on the strength of the Intensity values can change, depending on the level of thermal imaging camera, also weathered the changes in temperature could see. Intensity is the strength of weak rocks, the more value decrease, the temperature of the thermal imaging camera through the swell Intensity and notice that the temperature had an inverse relationship. Intensity value of the low strength of weak rock, but the value came out of the rocks have been proved to be largely dependent on the contrast. The contrast of the surface rocks are weathered dark Intensity values lower temperature to swell the contrary, the degree of weathering can be distinguished.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.861-868
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• 2017

Near band infrared imaging technique has adopted for imaging EL2 and shallow level distributions in undoped semi-insulating LEC GaAs. This technique, which relies on the mapping of near bandgap infrared transmission, is both rapid and non-destructive. Until now no quantitative analysis has been reported for near band edge region which gives the reverse contrast on EL2 absorption images. This paper presents the spectral, spatial and temperature dependence of photoquenching forward and inverse mechanism in the band edge domain for cells and walls and for direct and inverted contrast conditions during transitory regimes. The difference in the threshold for the EL2w and EL2b defects could be attributed to the contribution of a different electrical assistance due to a different species of impurities. Quantitative analysis results show an increased density of EL2w and a small reduction of EL2b in the region of the walls where there is a high density of dislocations.

• Imaging Science in Dentistry
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• v.53 no.2
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• pp.109-115
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• 2023

Purpose: The aim of this study was to evaluate changes in the trabecular bone through texture analysis and compare the texture analysis characteristics of different areas in patients with medication-related osteonecrosis of the jaw (MRONJ). Materials and Methods: Cone-beam computed tomographic images of 16 patients diagnosed with MRONJ were used. In sagittal images, 3 regions were chosen: active osteonecrosis(AO); intermediate tissue (IT), which presented a zone of apparently healthy tissue adjacent to the AO area; and healthy bone tissue (HT) (control area). Texture analysis was performed evaluating 7 parameters: secondary angular momentum, contrast, correlation, sum of squares, inverse moment of difference, sum of entropies, and entropy. Data were analyzed using the Kruskal-Wallis test with a significance level of 5%. Results: Comparing the areas of AO, IT, and HT, significant differences (P<0.05) were observed. The IT and AO area images showed higher values for parameters such as contrast, entropy, and secondary angular momentum than the HT area, indicating greater disorder in these tissues. Conclusion: Through texture analysis, changes in the bone pattern could be observed in areas of osteonecrosis. The texture analysis demonstrated that areas visually identified and classified as IT still had necrotic tissue, thereby increasing the accuracy of delimiting the real extension of MRONJ.

• 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.

• Development and Reproduction
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• v.21 no.3
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• pp.307-315
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• 2017

Surgical castration (also known as orchidectomy, ORX) has been frequently performed to avoid uncontrolled breeding. However, it has some serious disadvantages. Several laboratories have developed chemical castration methods, using bilateral intratesticular injection (BITI) of simple chemical solutions. The present study was undertaken to compare the effects of ORX and of hypertonic saline BITI on the androgen-sensitive tissues such as pituitary and hypothalamus. Serum testosterone (T) levels of ORX animals and hypertonic saline BITI animals (SAL) after 4 weeks of the manipulations exhibited significantly drops as compared with the levels of intact animals ( $Intact:ORX:SAL=7.74{\pm}1.31:1.34{\pm}0.19:1.28{\pm}0.18ng/ml$, p<0.001). Both ORX and BITI method induced similar stimulatory effects on the pituitary gonadotropin subunits and hypothalamic KiSS-1 gene expressions. In contrast, the effects of ORX and hypertonic saline BITI on hypothalamic GnRH gene expression were different from these gene expressions, shown an inverse relationship between the two groups ($Intact:ORX:SAL=1:0.45{\pm}0.06:1:2.07{\pm}0.41:1.51{\pm}0.37AU$; ORX, p<0.001; SAL, p<0.05). In conclusion, we provided evidence that hypertonic saline BITI method has equivalent efficacy of T depletion to surgical castration in rats. The present study suggests the hypertonic saline BITI could be a promising substitute to conventional surgical castration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1014-1017
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• 2007

Sound focusing technologies has been studied for various purposes from early 1990s. As a result, these technologies make us possible to apply in many uses. For example, we can treat tumors using focused ultrasonic waves without surgical knife and communicate in the ocean using time reversal array. Also applications for personal audio system become issues. Recently, as technologies are developing, in some applications, needs for regional focusing become increasing because previously suggested focusing methods, such as phase conjugation, time reversal and inverse filtering, were all about a point focusing. Therefore, studies on regional focusing method are essentially needed. Regional focusing method was firstly mentioned by Choi and Kim in 2002: acoustic contrast control. However, in regional focusing, physical interpretations between control variables and results are still not easy because of its complexity. In this regard, we tried to understand the relations between control variables and results in wavenumber domain and suggested a solution method for regional focusing: wavenumber spectrum matching. We also showed how to make spatially focused sound shape using the suggested method from the simplest case: line focusing.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.12
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• pp.5035-5042
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• 2014

Background: Knowledge and individual perceptions about adverse effects of all forms of tobacco exert direct influence on the level of tobacco consumption in various socio-demographic groups. The objective of this study was to determine the nature, extent and demographic correlates of knowledge, attitudes and perceptions of use of tobacco among adults in low and middle income countries. Materials and Methods: The Global Adult Tobacco Survey, conducted in fourteen different countries from 2008-2010, was sourced for the data analyzed in this study. Descriptive statistical analyses were conducted to determine the prevalent knowledge and individual perceptions amongst adults about all forms of tobacco consumption. Results: There was relatively high awareness about the harmful effects of smoking tobacco with main awareness being about its relationship with lung cancer (>90% in most countries). In contrast, there was relatively low awareness about harmful effects of smokeless tobacco (< 90% in all countries except India and Bangladesh), and observed correlation of smoking tobacco with heart attack (40.6% in China, 65.1% in India) and stroke (28.2% in China, 50.5% in India). Conclusions: A large proportion of adults living in low and middle income countries possess adequate knowledge about smoking tobacco but have inadequate awareness as well as false perceptions about smokeless forms of tobacco. Popular beliefs of inverse relationships of tobacco consumption with knowledge, attitudes and perception of populations towards tobacco are challenged by the findings of this study.