• Journal of the Society of Naval Architects of Korea
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• v.38 no.1
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• pp.86-98
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• 2001

Due to the rapid growth of ship building industry and the increment of ship construction in Korea, several hundred thousand of lifting lugs per year, have been installed at the lifting positions of ship block and removed after finishing their function, therefore. appropriate design system for the strength check or the optimal design of each lug structure has been required in order to increase the capability of efficient design. In this study, the design system of D-type lifting lug structure which is most popular and useful in shipyards, was developed for the purpose of initial design of lug structure. Developed system layout and graphic user interface for this design system based on the $C^{++}$ language were explained step by step. Through the illustration of one example of D-type lug designs, the efficiency of this design system was proved. Therefore, more efficient performance of practical lug structural design will be expected on the windows of personal computer using this design system.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.375-380
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• 2009

The authors had consisted the construction of shipyard must be investigated under the consideration of long term ship's demand and so the Floating Dock might be an alternative to the dry dock. This paper shows a development of Floating Dock Controller for Skid Launching System(SLS). While loading out a block to the Floating Dock and launching ship from the Floating Dock, the balancing of the ship and the dock is very important and achieved by adjusting the Ballast tank of the Floating Dock In this paper a Floating Dock Controller for SLS was developed through the on-line interface of VRC(Valve Remote Control), Tank Level & Draft Measuring System and Valve Control algorithm on Tank Plan. The control system developed was applied to a shipbuilding and verified good and stable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.291-297
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• 2014

Due to the rapid increase in demand for transportation of human and freight in modern railway systems, the CBTC system has been proposed, which is the solution for improvement of the line capacity that has been limited by the conventional track circuit based train control system. In the CBTC system, higher reliability of the communication system should be guaranteed for the safety of passengers and trains. However, due to the inherent characteristics of the wireless channel environment, performance degradations are inevitable. The diversity techniques can increase the reliability of data transmission using multiple antennas. In this paper, we investigate the performance of the STBC in the railway channel environment. Rician fading model is used for the viaduct scenarios which take important roles in the railway system. Also, considered is the Doppler effect which is an important factor in the mobile communication system. Simulations are performed to analyze the performance of the STBC in various channel environments. Results show that the performance degradation due to the phase error in viaduct scenarios is independent of the diversity order but is affected by the constellation of the modulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.963-972
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• 2002

An 8192-point pipelined FFT/IFFT processor core is designed, which can be used in multi-carrier modulation systems such as DUf-based VDSL modem and OFDM-based DVB system. In order to improve the signal-to-quantization-noise ratio (SQNR) of FFT/IFFT results, two-step convergent block floating-point (TS_CBFP) scaling is employed. Since the proposed TS_CBFP scaling does not require additional buffer memory, it reduces memory as much as about 80% when compared with conventional CBFP methods, resulting in area-and power-efficient implementation. The SQNR of about 60-㏈ is achieved with 10-bit input, 14-bit internal data and twiddle factors, and 16-bit output. The core synthesized using 0.25-$\mu\textrm{m}$ CMOS library has about 76,300 gates, 390K bits RAM, and twiddle factor ROM of 39K bits. Simulation results show that it can safely operate up to 50-㎒ clock frequency at 2.5-V supply, resulting that a 8192-point FFT/IFFT can be computed every 164-${\mu}\textrm{s}$. It was verified by Xilinx FPGA implementation.

• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.1-6
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• 2019

As the value of technical information increases, hacking attacks are trying to steal technical information through hacking. Recently, hacking of cryptocurrency exchanges is much easier to monetize than existing technical information, making it a major attack target for hackers. In the case of technical information, it is required to seize the technical information and sell it to the black market for cashing.In the case of cryptocurrency, most hacking attacks are concentrated on cryptocurrency exchanges because it is easy to cash out and not easy to track when successful hacking. Although technology cannot be hacked, cryptocurrency transactions traded on cryptocurrency exchanges are not recorded on the blockchain which is simply internal exchanges, so insiders may manipulate the quotes and leave gaps or leak out. Therefore, this research analyzes the recent hacking attacks of cryptocurrency exchanges and proposes solutions to secure cryptocurrency trading.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.3
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• pp.115-126
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• 2005

SHACAL-2 is a 256-bit block cipher with up to 512 bits of key length based on the hash function SHA-2. It was submitted to the the NESSIE project and was recommended as one of the NESSIE selections. In this paper, we present two types of related-key attacks called the related-key differential-(non)linear and the related-key rectangle attacks, and we discuss the security of SHACAL-2 against these two types of attacks. Using the related-key differential-nonlinear attack, we can break SHACAL-2 with 512-bit keys up to 35 out of its 64 rounds, and using the related-key rectangle attack, we can break SHACAL-2 with 512-bit keys up to 37 rounds.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.17-24
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• 2010

A differential fault attack(DFA) is one of the most efficient side channel attacks on block ciphers. Almost all block ciphers, such as DES, AES, ARIA, SEED and so on., have been analysed by this attack. In the case of the known DFAs on SEED, the attacker induces permanent faults on a whole left register of round 16. In this paper, we analyse SEED against DFA with differential characteristics and addition-XOR characteristics of the round function of SEED. The fault assumption of our attack is that the attacker induces 1-bit faults on a particular register. By using our attack, we can recover last round keys and the master key with about $2^{32}$ simple arithmetic operations. It can be simulated on general PC within about a couple of second.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.105-110
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• 2021

In this work, we design and implement a prototype of the mobile UX that works with blockchain-based smart contract systems so that artists and buyers who trade artworks through social media can find reliable trading partners and make secure transactions with each other. The developed prototype has the following characteristics. Utilizing prototypes, we cost-effectively validate the design of mobile UX(User Experience). First, we implement familiar UXs that social media users can use without additional explanation. Second, it is possible to check the reputation of the counterpart and encourage users to make fair deals that can increase their own reputation. Third, it implement the UX for common use by users around the world. Fourth, we design and implement to operate independently of the social media system.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.4
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• pp.115-124
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• 2021

Since function block diagram (FBD) programs are widely used to implement safety-critical systems, effective testing for FBD programs has become important. Mutation testing, a fault-based testing, is highly effective in fault detection but computationally expensive. To support testers for FBD programs, we propose an automated mutant generator for FBD programs. We designed the MuGenFBD tool with the cost and equivalent mutant issues in consideration. We conducted experiments on real industrial examples to present the performance of MuGenFBD. The results show that MuGenFBD can generate mutants for FBD programs automatically with low probability of equivalent mutants and low cost. This tool can effectively support mutation analysis and mutation-adequate test generation for FBD programs.

• Journal of Digital Convergence
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• v.19 no.4
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• pp.133-139
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• 2021

Due to the rapid progress in network technology, many research on content security technologies is also being conducted in the mobile digital content sector. In the meantime, content protection has been immersed in preventing illegal copying, certifying, and issuance/management certificates, but still have many vulnerabilities in managing or authenticating confidential information. This study aims to strengthen confidential information about content based on dual management of content download rights through mobile phone numbers or device numbers. It also protect replay-attack by building a secure mobile DRM system where digital content is safely distributed based on a three-stage user authentication process. In addition, blockchain-based content security enhancements were studied during the primary/secondary process for user authentication for the prevention of piracy and copyright protection. In addition, the client authentication process was further improved through three final stages of authorization in the use of illegal content, considering that legitimate users redistributed their content to third-party.