• Journal of Satellite, Information and Communications
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• v.3 no.2
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• pp.32-37
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• 2008

Global Navigation Satellite System (GNSS) is been developing in many countries. The satellite navigation system has the importance in economic and military fields. For utilizing satellite navigation system properly, the technology of GNSS Ground Station is needed. GNSS Ground Station monitors the signal of navigation satellite and analyzes navigation solution. This study deals with the navigation software for GNSS Ground Station. This paper will introduce the navigation solution algorithm for GNSS Ground Station. The navigation solution can be calculated by the code-carrier smoothing method, the Kalman-filter method, the least-square method, and the weight least square method. The performance of each navigation algorithm in this paper is presented.

• Journal of the Korea Society of Computer and Information
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• v.24 no.1
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• pp.25-32
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• 2019

With the rapid development of artificial intelligence technology, the patenting activities related to the fields of AI is increasing worldwide. In particular, a share of patent filed in China has exploded in recent years and overtakes the numbers in the US. In the present study, we focus our attention on the patenting activity of China and the US. We analyzed 6,281 and 13,664 patent applications in the US and China respectively between 2008 and 2018, and belonging to the "G06F(Electric Digital Data Processing)", "G06N(Computer Systems Based on Specific Computational Models)", "H04L(Transmission of Digital Information)" and nine more relevant technological classes, as indicated by the International Patent Classification(IPC). Our analysis contributes to: first, the understanding of patent application trends from foreign countries filed in the US and China, 2) patent application status by applicants category such as companies, universities and individuals, 3) the development direction and forecasting vacant technology of AI according to main IPC code. Through the analysis of this paper, we can suggest some implications for patent research related to artificial intelligence in Korea. Plus, by analyzing the most recent patent data, we can provide important information for future artificial intelligence technology research.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.127-132
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• 2024

With the rapid evolution of the Internet, the application of artificial intelligence fields is more and more extensive, and the era of AI has come. At the same time, adversarial attacks in the AI field are also frequent. Therefore, the research into adversarial attack security is extremely urgent. An increasing number of researchers are working in this field. We provide a comprehensive review of the theories and methods that enable researchers to enter the field of adversarial attack. This article is according to the "Why? → What? → How?" research line for elaboration. Firstly, we explain the significance of adversarial attack. Then, we introduce the concepts, types, and hazards of adversarial attack. Finally, we review the typical attack algorithms and defense techniques in each application area. Facing the increasingly complex neural network model, this paper focuses on the fields of image, text, and malicious code and focuses on the adversarial attack classifications and methods of these three data types, so that researchers can quickly find their own type of study. At the end of this review, we also raised some discussions and open issues and compared them with other similar reviews.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.46.2-46.2
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• 2010

A magnetosonic wave is a longitudinal wave propagating perpendicularly to the magnetic fields and involves compression and rarefaction of the plasma. Lee and Kim (2000) investigated the theoretical solution for the evolution of nonlinear magnetosonic waves in the homogeneous space which adopt the approach of simple waves. We confirm the solution using a one-dimensional MHD code with Total Variation Diminishing (TVD) scheme. Then we apply the solution for the solar wind profiles. We examined the properties of nonlinear waves for the various initial perturbations at near the Lagrangian (L1) point. Also we describe waves steepening process while the shock is being formed by assuming different timescales for a driving source.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.4
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• pp.174-183
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• 2017

Numerical simulations were performed about the green water problem of a FPSO. Three regular waves in head sea were tested. A rectangular box-shaped FPSO was considered and it is assumed there is a vertical wall on the deck. For the numerical simulations, an open-source CFD code, OpenFOAM, was applied to solve the present problems. Focus is on wave fields around the FPSO, water flows and impact pressures on the deck. For the validation, the present calculation results were compared with the existing experimental of Lee et al. (2012) and Changwon university in KTTC Cooperative Study Report (2015). The statistical values and spatial distribution of the peak pressures are directly compared with the experimental data. Some discussions are made on the effects of the domain breadth on the Green water impact pressure.

• Journal of the Korean Society of Costume
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• v.39
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• pp.59-77
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• 1998

This paper is focused on the traditional sash weaving handicraft of‘She’ethnic group, which is located in Fujian, Zhejiang, Jiangxi, Guangdong province of China. This research is main-ly based on the field work, analyzed and inter-preted the traditional sash in systematic and reasoned way. The summary of this study are as follows : 1. On its technological aspect, weaving structure of the traditional sash is made of warp rod backed weaving. The used tool is primitive one but the weaving process includes scientific method. 2. From the social-cultural point of view, the sash ha been the symbol of love towards her lover. Every woman of this group had taken training for this sash weaving from a child. 3. On its ethnological aspect, it has been long history and has interchanged with other ethnic group like Miao, Han and also Okinawa country of Japan. The pattern inside this sash are almost looks like characters, but they are not Chinese characters whereas are the inde-pendent code of‘She’ group and have been inherent from ancestors and which will be tran-smitted to their posterity. These independent code of‘She’group are the traditional message to their later generation implicating their natural circumstances, human relationship, ethnic myth, spirit etc. 4. I recognize that the pattern inside the sash is defined as the communicative code and in comparison to language, it is more repetition and less apparent as close code. Nowadays China has been developed es-pecially in the economical fields rapidly. Under the circumstances traditional weaving culture of ethnic groups has been facing a crisis of disappearance, which will be a great loss for the country as well as the human beings. For this reason, I emphasize that it is very immediate to make co-researches into the material culture of Chinese ethnic groups.

• The Journal of the Korea Contents Association
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• v.7 no.6
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• pp.185-194
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• 2007

Today, there is in the world-wide cognition about RFID technology due to established standard, EPC(Electronic Product Code). RFID technology will have wide influence over various fields. Especially, RFID technology's advantages will have positive influence on logistics field. We can solve limited various problems presented in SCM by applying RFIB technology. We can have higher cantrol system, better benefits and actual decision information. Many organizations, however, still have hesitated now because RFID technology has not been validated and RFID technology is in early stage. Other problems are employee resistance against new technology and lack of academic empirical research on assimilation RFID technology for organization. Above reasons I mentioned make me study on analysis on assimilation RFID technology decision in SCM field. This study attempts to analyze the assimilation RFID technology factor from previous researches by using AHP. This outcomes of study will be helpful when we assimilate RFID technology in SCM fields.

• Nuclear Engineering and Technology
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• v.41 no.8
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• pp.1025-1044
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• 2009

Systematic research has been conducted by KAERI to develop a supercritical carbon dioxide Brayton cycle energy conversion system coupled with a sodium cooled fast reactor. For the development of the supercritical $CO_2$ Brayton cycle ECS, KAERI researched four major fields, separately. For the system development, computer codes were developed to design and analyze the supercritical $CO_2$ Brayton cycle ECS coupled with the KALIMER-600. Computer codes were developed to design and analyze the performance of the major components such as the turbomachinery and the high compactness PCHE heat exchanger. Three dimensional flow analysis was conducted to evaluate their performance. A new configuration for a PCHE heat exchanger was developed by using flow analysis, which showed a very small pressure loss compared with a previous PCHE while maintaining its heat transfer rate. Transient characteristics for the supercritical $CO_2$ Brayton cycle coupled with KALIMER-600 were also analyzed using the developed computer codes. A Na-$CO_2$ pressure boundary failure accident was analyzed with a computer code that included a developed model for the Na-$CO_2$ chemical reaction phenomena. The MMS-LMR code was developed to analyze the system transient and control logic. On the basis of the code, the system behavior was analyzed when a turbine load was changed. This paper contains the current research overview of the supercritical $CO_2$ Brayton cycle coupled to the KALIMER-600 as an alternative energy conversion system.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.3
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• pp.245-255
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• 2023

Time comparison techniques are necessary for generating and keeping Coordinated Universal Time (UTC) and distributing standard time clocks. Global Navigation Satellite System (GNSS) Common View, GNSS All-in-View, Two-Way Satellite Time and Frequency Transfer (TWSTFT), Very Long Baseline Interferometry (VLBI), optical fiber, and Network Time Protocol (NTP) based methods have been used for time comparison. In these methods, GNSS based time comparison techniques are widely used for time synchronization in critical national infrastructures and in common areas of application such as finance, military, and wireless communication. However, GNSS-based time comparison techniques are vulnerable to jamming or interference environments and it is difficult to respond to GNSS signal disconnection according to the international situation. In response, in this paper, Code-Division Multiple Access (CDMA) based All-to-All TWSTFT operation method is proposed. A software-based simulation platform also was designed for performance analysis in multi-TWSTFT signal environments. Furthermore, code and carrier measurement jitters were calculated in multi-signal environments using the designed simulation platform. By using the technique proposed in this paper, it is anticipated that the TWSTFT-based time comparison method will be used in various fields and satisfy high-performance requirements such as those of a GNSS master station and power plant network reference station.