• International Journal of Computer Science & Network Security
• /
• v.23 no.9
• /
• pp.8-16
• /
• 2023

In Japan, high-speed ground transportation service using linear motors at speeds of 500 km/h is scheduled to begin in 2027. To accommodate 5G services in trains, a subcarrier spacing frequency of 30 kHz will be used instead of the typical 15 kHz subcarrier spacing to mitigate Doppler effects in such high-speed transport. Furthermore, to increase the cell size of the 5G mobile system, multiple base station antennas will transmit identical downlink (DL) signals to form an expanded cell size along the train rails. In this situation, the forward and backward antenna signals are Doppler-shifted in opposite directions, respectively, so the receiver in the train may suffer from estimating the exact Channel Transfer Function (CTF) for demodulation. In a previously published paper, we proposed a channel estimator based on Delay and Doppler Profiler (DDP) in a 5G SISO (Single Input Single Output) environment and successfully implemented it in a signal processing simulation system. In this paper, we extend it to 2×2 MIMO (Multiple Input Multiple Output) with spatial multiplexing environment and confirm that the delay and DDP based channel estimator is also effective in 2×2 MIMO environment. Its simulation performance is compared with that of a conventional time-domain linear interpolation estimator. The simulation results show that in a 2×2 MIMO environment, the conventional channel estimator can barely achieve QPSK modulation at speeds below 100 km/h and has poor CNR performance versus SISO. The performance degradation of CNR against DDP SISO is only 6dB to 7dB. And even under severe channel conditions such as 500km/h and 8-path inverse Doppler shift environment, the error rate can be reduced by combining the error with LDPC to reduce the error rate and improve the performance in 2×2 MIMO. QPSK modulation scheme in 2×2 MIMO can be used under severe channel conditions such as 500 km/h and 8-path inverse Doppler shift environment.

• Corrosion Science and Technology
• /
• v.12 no.6
• /
• pp.280-287
• /
• 2013

Flow accelerated corrosion(FAC) of the carbon steel piping in pressurized water reactors(PWRs) has been major issue in nuclear industry. Severe accident at Surry Unit 2 in 1986 initiated the worldwide interest in this area. Major parameters influencing FAC are material composition, microstructure, water chemistry, and hydrodynamics. Qualitative behaviors of FAC have been well understood but quantitative data about FAC have not been published for proprietary reason. In order to minimize the FAC in PWRs, the optimal method is to control water chemistry factors. Chemistry factors influencing FAC such as pH, corrosion potential, and hydrazine contents were reviewed in this paper. FAC rate decreased with pH up to 10 because magnetite solubility decreased with pH. Corrosion potential is generally controlled dissolved oxygen (DO) and hydrazine in secondary water. DO increased corrosion potential. FAC rate decreased with DO by stabilizing magnetite at low DO concentration or by formation of hematite at high DO concentration. Even though hydrazine is generally used to remove DO, hydrazine itself thermally decomposed to ammonia, nitrogen, and hydrogen raising pH. Hydrazine could react with iron and increased FAC rate. Effect of hydrazine on FAC is rather complex and should be careful in FAC analysis. FAC could be managed by adequate combination of pH, corrosion potential, and hydrazine.

• Korean Journal of Community Nutrition
• /
• v.21 no.4
• /
• pp.321-331
• /
• 2016

Objectives: The purpose of this study was to examine the economic characteristics of single-person households and explain the effects of them on the food service industry. Methods: For this paper, I analysed the data related with single-person households and the food service industry in two surveys, Household Income and Expenditure Survey and Wholesale and Retail Trade Survey published by Statistics Korea from 2006 to 2015, with an empirical test performed utilizing these data. The indicators of the age of householders, disposable income per capita, and the rate of household of worker were compared between single and multi-person households. Furthermore, sales and the number of establishments in the food service industry were used as industry-variables, and disposable income, eating-out expenses and the rate of single-person households as the household-variables were used in a panel analysis. Results: The results showed that household incomes were lower, age of householder was higher, and the percentage of household of worker was lower in single-person households in contrast to multi-person households. According to the empirical analysis, eating-out expenses of single-person households, in comparison to multi-person households, has significantly positive effects on the growth of the food service industry. This means that the recent trend of increasing numbers of single-person households may help the growth of the food service industry. Conclusions: The growth in the rate of single-person households has been one of the most striking demographic shifts in recent decades. Their economic characteristics and the effects were analyzed to give the managers in the food service industry and the policy-makers useful information in dealing with this new trend. Moreover, in considering the fact that single-person households eat out more frequently than multi-person households, the food service business should develop the managerial strategies focused on acclimatizing to single-person households.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.28 no.1
• /
• pp.85-93
• /
• 2018

Biometric user authentications, day after day, propagate more to human life instead of traditional systems which use passwords and ID cards. However, most of these systems have many problems for given biometric information such noisy data, low-quality data, a limitation of recognition rate, and so on. To deal with these problems, I used Dual QML which is non-linear classification for classifying correctly the real-world data and then proposed preprocessing method for increasing recognition rate and performance by segmenting a specific region on an image. The previous published Dual QML used face, palmprint, ear for the experiment. In this paper, I used iris for experiment and then proved excellence of Dual QML at iris recognition. Finally I demonstrated these results (e.g. increasing recognition rate and performance, suitability for iris recognition) through experiments.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.2
• /
• pp.215-220
• /
• 2009

LR-WPAN(Low-Rate Wireless Personal Area Network) hewn as IEEE 802.15.4 is considered as one of the most suitable specifications published until now to accomplish USN(Ubiquitous Sensor Network). In this paper we simulate interference effects to other systems if LR-WPAN will be used in 900MHz. In considering the current usage situation of 900MHz frequency band, we can think LR-WPAN shares the frequency band of $908.5{\sim}914MHz$ assigned for RFID/USN. The simulation results of the case of LR-WPAN and RFID/USN sharing the frequency band show that the probability of interference of LR-WPAN to CT1 and RFID is 2.5% and 2.1%, respectively. In order to avoid interference effects to public communications, simulations results show that the protection distance of about loom is needed.

• Archives of Plastic Surgery
• /
• v.46 no.4
• /
• pp.311-317
• /
• 2019

Background Since the initial Research and Reconstruction Forum (R&R Forum) in 2011, the R&R Forum, Korean Society for Aesthetic Plastic Surgery (KSAPS), and Korean Society of Plastic and Reconstructive Surgeons (KSPRS) have held annual meetings. This study was conducted to provide updated information on the publication rate of presentations at those meetings. Methods Plastic surgery-related abstracts presented at the R&R Forum, KSAPS, and KSPRS between 2011 and 2015 were collected. The sessions were divided into free papers, posters, and e-presentations (or e-posters) for each annual meeting. Abstract publication status was confirmed through PubMed, Google Scholar, the KCI-Korean Journal Database, and the KM-base database. Results In total, 2,335 abstracts were presented in the free paper, poster, and e-presentation sessions. Of these, 622 (26.6%) were published. The overall publication rates were 240 of 684 abstracts (35.1%) presented at the R&R Forum, 56 of 216 abstracts (25.9%) presented at the KSAPS meetings, and 326 of 1,435 abstracts (22.7%) presented at the KSPRS meetings. In terms of specific annual meetings, the 2014 R&R Forum had the highest publication rate (39.9%), followed by the 2015 KSAPS (31.0%) and the 2015 KSPRS (28.8%). Conclusions Scientific researchers present diverse results at these professional meetings, with a focus on innovative surgical techniques and improved surgical outcomes. This is our second study on this topic. Despite its limitations, this study indirectly shows that the recognition of Korean plastic surgeons and the quality of the annual meetings of Korean societies of plastic surgery have risen to the global level.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.38
• /
• pp.327-376
• /
• 2008

China is marking 9.4% annual growth rate in average since 1978. GDP reached $1090 in 2003 as the first time and China ranked at 4th with their economy size in 2006. One of the remarkable change in China is the extension of foreign open-door policy. China joined WTO in the end of 2001 and it strengthen the foundation of Chinese market economy structure and encouraged the inflow of foreign capital. While 400 of the 500 global corporations advanced into China, the economy trade has been rapidly increasing between Korea and China. The economy trade in both countries has been regularized since 1992 and the annual trade is tending upwards in last 15 years. Korean trade toward China reached 134,400 million which is increased 27 times compared with the total of 1982. In this period, Korean trade toward China marked 24.5% in Export increasing rate and 16.7% in import increasing rate. China became the 2nd biggest export country of Korea in 2001 and became the top in 2003. As the China foreign direct investment has been increasing rapidly, the number of Korean companies advanced into China has been remarkably increasing. By focusing on a thorough review of the nationally published documents of Korean-Chinese business management research during more than two decades (1981-2004), the present paper has been systematically classified and analyzed the current status of Korean-Chinese business management research. The paper raised some important issues regarding Korean-Chinese business management research and predominantly, its future prospects are outlined. In the paper, the documents which are registered in the Korean Academic Processing Foundation registration of journals and candidate registration of journals have been classified by: research purpose, main subject, research method and the results. Careful analysis among the research clarified the active and inactive business management research fields. This clarification enables us to get a better understanding of the current research of Korean-Chinese business management, and more importantly, it pointed out to the direction of future development of research. In addition, the systematic classification made by this paper may contribute to the decision making of subject index of Korean-Chinese business management research since there has been no classification standard of it until now.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.33 no.5
• /
• pp.801-811
• /
• 2023

With the cyber incidents increasing every year, opinions are being raised that legal system relating to incident reporting needs to be revised to improve the cyber incident reporting rate, etc. Accordingly, this paper suggests a legal improvement to enhance the effectiveness of cyber incident reporting. First, by analyzing domestic media coverage, this paper defines the problems which need to be improved regarding an incident reporting system as "unreported" and "not timely reporting". Then, this paper finds four requirements for legal improvement like "a reporting entity", "a starting point of reporting", "a reporting deadline" and "a protection of reporting information" by analyzing the relationship between reporting relating problems and issues published by overseas institutions and additionally by analyzing the need to revise the law. Finally, through an analysis of legislative cases, this paper suggests a legal improvement for the requirements.

• Structural Engineering and Mechanics
• /
• v.55 no.3
• /
• pp.655-674
• /
• 2015

In this paper, a new and simplified method is presented in which the natural frequencies of the uniform and non-uniform beams are calculated through simple mathematical relationships. The various vibration problems such as: Rayleigh beam under variable axial force, axial vibration of a bar with and without end discrete spring, torsional vibration of a bar with an attached mass moment of inertia, flexural vibration of the beam with laterally distributed elastic springs and also flexural vibration of the beam with effects of viscose damping are investigated. The governing differential equations are first obtained and then; according to a harmonic vibration, are converted into single variable equations in terms of location. Through repetitive integrations, the governing equations are converted into weak form integral equations. The mode shape functions of the vibration are approximated using a power series. Substitution of the power series into the integral equations results in a system of linear algebraic equations. The natural frequencies are determined by calculation of a non-trivial solution for system of equations. The efficiency and convergence rate of the current approach are investigated through comparison of the numerical results obtained with those obtained from other published references and results of available finite element software.

• Structural Engineering and Mechanics
• /
• v.58 no.1
• /
• pp.181-197
• /
• 2016

In this paper, we investigated the propagation of surface waves in a nonhomogeneous rotating fibre-reinforced viscoelastic anisotropic media of higher order of nth order including time rate of strain. The general surface wave speed is derived to study the effect of rotation on surface waves. Particular cases for Stoneley, Love and Rayleigh waves are discussed. The results obtained in this investigation are more general in the sense that some earlier published results are obtained from our result as special cases. Also results for homogeneous media can be deduced from this investigation. For order zero our results are well agreed to fibre-reinforced materials. Also by neglecting the reinforced elastic parameters, the results reduce to well known isotropic medium. It is also observed that, surface waves cannot propagate in a fast rotating medium. Comparison was made with the results obtained in the presence and absence of rotation and parameters for fibre-reinforced of the material medium Numerical results are given and illustrated graphically. The results indicate that the effect of rotation and parameters for fibre-reinforced of the material are very pronounced.