• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.57-67
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• 2005

Fast scalar multiplication of points on elliptic curve is important for elliptic curve cryptography applications. In order to vary field sizes depending on security situations, the cryptography coprocessors should support variable length finite field arithmetic units. To determine the effective variable length finite field arithmetic architecture, two well-known curve scalar multiplication algorithms were implemented on FPGA. The affine coordinates algorithm must use a hardware division unit, but the projective coordinates algorithm only uses a fast multiplication unit. The former algorithm needs the division hardware. The latter only requires a multiplication hardware, but it need more space to store intermediate results. To make the division unit versatile, we need to add a feedback signal line at every bit position. We proposed a method to mitigate this problem. For multiplication in projective coordinates implementation, we use a widely used digit serial multiplication hardware, which is simpler to be made versatile. We experimented with our implemented ECC coprocessors using variable length finite field arithmetic unit which has the maximum field size 256. On the clock speed 40 MHz, the scalar multiplication time is 6.0 msec for affine implementation while it is 1.15 msec for projective implementation. As a result of the study, we found that the projective coordinates algorithm which does not use the division hardware was faster than the affine coordinate algorithm. In addition, the memory implementation effectiveness relative to logic implementation will have a large influence on the implementation space requirements of the two algorithms.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.40-48
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• 2008

Security of self organized mobile ad hoc networks is an important issue because administration information in the networks is managed by the constituent nodes. Especially authentication mechanism is necessary for trust setup between newly joining nodes and the network. The authentication models and protocols which are based on the wireline infrastructure could not be practical for mobile ad hoc network. Although public key algorithm-based method is widely used for authentication, it is not easy to be applied to mobile ad hoc networks because they do not have infrastructure such as centralized CA which is needed for certificate verification. In this paper, we consider the public key based random CA group method proposed in [1] to provide efficient authentication scheme to mobile ad hoc networks and analyze the performance of the method, which is then compared to the home CA method. From the analysis results, we see that the random CA method where the function of CA is distributed to some mobile nodes and the authentication information is propagated to randomly chosen CAs shows higher reliability and lower cost than home CA method.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.31-36
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• 2014

Security of chaos communication system that has characteristic of sensitive initial conditions is superior to digital communication systems, but BER(Bit Error Rate) performance is evaluatied badly. So, studies in order to improve the BER performance is important. existing studies, BER performance of proposed chaos transceiver is possible to improve than the CDSK(Correlation Delay Shift Keying) system because it has characteristic that has very few addition elements like noise signal except for the desired signal. Chaos communication system has many symbols because it spreads according to characteristic of chaos map. Therefore, study that can have the good data rate in chaos communication system is required. Information bits of existing chaos modulation system are modulated as -1 and 1 on the basis of BPSK system. However, instead of BPSK system, if chaos communication system is applied high level modulation systems such as QPSK system and 16QAM system, it is possible to have good data rate because more data are transmitted at a time. In the paper, when QPSK system and 16QAM system are applied to proposed chaos transceiver in existing study, we evaluate the SER(Symbol Error Rate) performance and compare the each performance. Also, when QPSK system and 16QAM system are applied to proposed chaos transceiver, we evaluate the anti-jamming performance of proposed system.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.11 no.2
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• pp.63-73
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• 2016

In these days startup became one of the most hot issue in business world. The problem is many startup couldn't overcome the valley of death. For this reason many startup want to funded by venture capital. However startup's business is trade secret itself, so they have to make strategic approach to venture capital. The purpose of study is to find the way to make strategic decision for startup. By analyzing the relation between startup's characteristic and venture capital's investment portfolio. Four famous venture capital(Sequoia capital, Lightspeed venture, Firstround and Khosla venture) and their seed invested startup Dropbox, Airbnb, Snapchat, Uber and Instacart was selected for this study. As a result, each venture capital has their own invest category characteristic and their seed funding belong to their category. Moreover, between seed funded startup and 36,4% of 244 past invented company shown vertical relationship, beside 0.5% of past 244 invested company shown horizontal relationship. This result shown the importance of the relation between startup's characteristic and venture capital's portfolio. Startup have to check the venture capital's portfolio for the strategic approach for funding and venture capital have to make mutual positive portfolio for decreasing the risk.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.7
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• pp.143-148
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• 2020

Recently, web services have been expanded to various areas with the evolution of cloud environment. Whenever a user accesses a web service, the user's log information is stored in the web server. This log information is used as data to analyze the user's web service tendencies and is also used as important data to track the user's system access when a security problem in the system occurs. Currently, most web servers manage user log information in a centralized manner. When user log information is managed in a centralized manner, it is simple in the side of operation, but has a disadvantage of being very vulnerable to external malicious attacks. In the case of centralized management, user log information stored in the web server can be arbitrarily manipulated by external attacks, and in severe cases, the manipulated information can be leaked. In this case, it not only decreases the trust of the web service, but also makes it difficult to trace the source and cause of the attack on the web server. In order to solve these problems, this paper proposes a new method of managing user log information in a cloud environment by applying blockchain technology as an alternative to the existing centralized log management method. The proposed method can manage log information safely from external attacks because user log information is distributed and stored in blockchain on a private network with cloud environment.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.777-786
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• 2009

In recent, the ships of the Republic of Korea have been suffered from acts of piracy at the seas. With the increase of the threats from the acts of piracy and armed robbery against ships, some of the countries have dispatched their navy warships to the international waters and to carry out military operation against the pirates. However, the total eradication of the piracy has not been achieved due to the lack of international cooperation and the limitation of the international maritime convention itself. In addition, the absence of counter-measures to be taken by the ships itself including the employment of the professional maritime security forces should not be overlooked. In this connection, this paper examined the reality of the piracy together with armed robberies at the seas and the problems in the response were also analyzed. Based on the research, it suggested some possible measures with special reference to the private security. The limitation of this paper is that it only focus on the aspect of the private security. In this paper, the cooperation among the countries according to the maritime convention and internationally accepted norms and practices. To achieve the goals of this paper, through the comparative review of the related literatures, the practical measures applicable to the prevention of the piracy were suggested.

• The Journal of Engineering Geology
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• v.7 no.2
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• pp.151-159
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• 1997

Since healed microcracks in quartz grain of grantic rocks within the same mass have identical preferred orientations, the oreintations of granitic cores may be determined if the distinctive feature of healed microcracks can be used.In this study, the possibility of determining orientations of granitic cores using healed microcrack orientations were examined using samples from the borehole drilled to 200 m in depth at the Hongcheon. Eight sections whose core recoveries are 100% were selected. Two to six samples were collected in each section and orientations of healed microcracks in each sample were measured. Healed microcracks in samples from each section show almost identical orientations. The error range for sections with only one preferred orientations is within $\pm$5$^{\circ}$, indicating that correct orientations of core can be determined. However, orientations of cores in sections which have 2 or more healed microcrack orientations should be determined using orientations as well as distribution of peaks of orientations. The error range for this case is lager than former one and is within $\pm$15$^{\circ}$. The orientations of joint which is very impontant factor for designing tunnel and slope stability can be determined using healed microcrack orientation in cores.

• Korean Security Journal
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• no.10
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• pp.243-272
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• 2005

All measures related to the safety of the casino facilities guarantee safety of facilities that are targets of security guards, protect lives and properties, minimize risks of artificial and natural disaster and crimes. In summary, plan for responding to safety and accidents should be developed not only for the casino facilities but also for the facilities of annexed buildings, and lives and properties of customers and employees. Determine areas in the casino facilities that are prone to accidents and set around-the-clock guard in the areas or maintain surveillance with CCTV and prevent accidents through continuous patrol. These are the most basic and the most important requirements in safety. In addition, casinos which prompt gambling are causing economic and psychological treats to families. To resolve these social issues, casinos have adopted limited entrance system. To support this system, new forms of machine security systems such as video automatic recognition system of fingerprint pattern recognition system should be adopted too. In addition, security guards in casino facilities need to instill themselves with a sense of ownership as well as a strong sense of mission to do the best for customer security and to protect the company assets and employees and manage accidents that could occur without notice. Security guards should do their best to enable manage accidents that could occur without notice. Security guards should do their best to enable tourists who are on the rise due to increase in advanced country-style tourism and leisurely activities to get the utmost satisfaction from the casinos, and as a leader of private security company, establish the foundation for security based on the characteristics of security in Korea.

• Korean Security Journal
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• no.36
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• pp.443-467
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• 2013

The purpose of this study is to introduce United States Coast Guard (USCG) in order to suggest a direction to advance the system of Korea Coast Guard. After the effect of United Nations on the Law of the Sea in 1994, the world is facing with new era of maritime age with emergence of new maritime border 'Exclusive Economic Zone(EEZ)'. Along with new maritime era, Korea also has been facing with the conflicts caused from EEZ. Also, there is a increasing concern about maritime safety and security since people looking for maritime tourism and leisure sports are dramatically increasing in Korea. Moreover, national security matters are a big issue in Korea due to the several incidents occurred in the sea such as the attack on Yeon-Pyung Island and the sinking of Cheonan naval vessel. Arising concern on these issues in maritime space requires Korea Coast Guard to handle these effectively. However, the systematical and structural limitation of Korea Coast Guard limits the effective management of recent issues. The United States Coast Guard which is considered as one of the military force in the United States has continuously reformed and developed its system and structure to better handle the maritime safety and security issues through developing project such as the Integrated Deep Water system. Also, maritime police system and structure in the United States is different with in Korea. This study expects to suggest a way to advance the system and structure of Korea Coast Guard through examination of United States Coast Guard and comparing maritime police system and structure between Korea and the United States in order to properly deal with the maritime safety and security issues arising recently.

• Journal of Korea Multimedia Society
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• v.6 no.1
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• pp.148-160
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• 2003

TMA(Tissue Mineral Analysis) is very popular method in hair mineral analysis for health care professionals in over 48 countries medical center. Assesment of nutritional minerals and toxic elements in the hair is very important not only for determining adequacy, deficiencies and unbalance, but also for assessing their relative relationships in a body. In Korea, there are some problems in TMA method. Because of not haying a medical information database which is suitable for korean to do analyze, the requested TMA has to send to TEI-USA. However, as the TMA results from TEI-USA is composed of English documents and graphic files prohibited to open, its usability is very low and a lot of dollars has to be payed. Also, it can make some problems in the reliability of the TMA results, since the TMA results are based on the database of western health and mineral standards, To solve these problems, I developed the first Medical Information System of TMA in Korea here. The system can analyze the complex tissue mineral data with multiple stage decision tree classifier. It is also constructed with multiple fuzzy database and hence analyze the TMA data by fuzzy inference methods. The effectiveness test of this systems can be shown the increased business efficiency and satisfaction rate 86% and 92% respectively.