• Proceedings of the KIEE Conference
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• 1985.07a
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• pp.231-233
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• 1985

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.625-634
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• 2002

Cryptography is the methods of making and using secret writing that is necessary to keep messages private between two parties. Cryptography is compute-intensive algorithm and needs cpu resource excessively. To solve these problems, there exists hardware approach that implements cryptographic algorithm with hardware chip. In this paper, we presents the design and implementation of cryptographic hardware and compares its performance with software cryptographic algorithms. The experimental result shows that the hardware approach causes high I/O overheads when it transmits data between cryptographic board and host cpu. Hence, low complexity cryptographic algorithms such as DES does not improve the performance. But high complexity cryptographic algorithms such as Triple DES improve the performance with a high rate, roughly from two times to Sour times.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.41-48
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• 2013

An efficient encryption algorithm based on the Data Encryption Standard (DES) for personal cloud computing environments is presented. The proposed algorithm improves data privacy, security and also encryption speed, compared with the triple DES. The improvement of the proposed algorithm stems from enhanced privacy inherent from the use of spread random interleaver in the place of the known substitution table for initial and final permutations in the DES algorithm. The simulation results demonstrate that the interleaver based DES (I-DES) is found to run faster than the triple DES algorithm and also offer improved security. The proposed algorithm also offers encryption for variable-length data using the Cipher Block Chaining (CBC).

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.709-717
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• 2012

The round reduction on block cipher is a fault injection attack in which an attacker inserts temporary errors in cryptographic devices and extracts a secret key by reducing the number of operational round. In this paper, we proposed an improved round reduction method to retrieve master keys by injecting a fault during operation of loop statement in the Triple DES. Using laser fault injection experiment, we also verified that the proposed attack could be applied to a pure microprocessor ATmega 128 chip in which the Triple DES algorithm was implemented. Compared with previous attack method which is required 9 faulty-correct cipher text pairs and some exhaustive searches, the proposed one could extract three 56-bit secret keys with just 5 faulty cipher texts.

• The Journal of the Acoustical Society of Korea
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• v.14 no.5
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• pp.44-50
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• 1995

This paper describes a large-vocabulary continuous speech recognition system using continuous hidden Markov models for the Korean language. To improve the performance of the system, we study on the selection of speech modeling units, inter-word modeling, search algorithm, and grammars. We used triphones as basic speech modeling units, generalized triphones and function word-dependent phones are used to improve the trainability of speech units and to reduce errors in function words. Silence between words is optionally inserted by using a silence model and a null transition. Word pair grammar and bigram model based oil word classes are used. Also we implement a search algorithm to find N-best candidate sentences. A postprocessor reorders the N-best sentences using word triple grammar, selects the most likely sentence as the final recognition result, and finally corrects trivial errors related with postpositions. In recognition tests using a 3,000-word continuous speech database, the system attained $93.1\%$ word recognition accuracy and $73.8\%$ sentence recognition accuracy using word triple grammar in postprocessing.

• The Journal of Society for e-Business Studies
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• v.19 no.1
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• pp.131-143
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• 2014

A triple database consisting of a number of three-column tables require high cost of query processing, whereby building a shortcut is known as an effective way to reduce the cost. It is important to figure out what shortcuts needs to be selectively built. Most shortcut selection algorithms make use of a benefit model that considers the query frequency. However they work poor to reflect the database update. In this paper, we consider a benefit model for triple databases. The model considers not only the profit of query response times but also the building and maintenance costs of the shortcuts. We apply the model to design a benefit function which can be plugged in a greedy-based shortcut selection algorithm. We perform the empirical experiments on a real-world dataset and analyze the effect of each factor employed in the benefit function.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.592-603
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• 2015

In this paper, an optical implementation of a novel asymmetrical cryptosystem combined with D-H secret key sharing and triple DES is proposed. The proposed optical cryptosystem is realized by performing free-space interconnected optical logic operations such as AND, OR and XOR which are implemented in Mach-Zehnder type interferometer architecture. The advantage of the proposed optical architecture provides dual outputs simultaneously, and the encryption optical setup can be used as decryption optical setup only by changing the inputs of SLMs. The proposed cryptosystem can provide higher security strength than the conventional electronic algorithm, because the proposed method uses 2-D array data, which can increase the key length surprisingly and uses 3DES algorithm, which protects against “meet in the middle” attacks. Another advantage of the proposed asymmetrical cryptosystem is that it is free to change the user’s two private random numbers in generating the public keys at any time. Numerical simulation and performance analysis verify that the proposed asymmetric cryptosystem is effective and robust against attacks for the asymmetrical cipher system.

• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.615-625
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• 2012

GPS attitude outputs or carrier phase observables can be effectively utilized to compensate the attitude error of the strapdown inertial navigation system. However, when the integer ambiguity is not correctly resolved and/or a cycle slip occurs, an erroneous GPS output can be obtained. If the erroneous GPS output is applied to the attitude determination GPS/INS (ADGPS/INS) integrated navigation system, the performance of the system can be degraded. This paper proposes an ADGPS/INS integration system using the triple difference carrier phase observables. The proposed integration system contains a cycle slip detection algorithm, in which the inertial information is combined. Computer simulations and flight test were performed to verify effectiveness of the proposed navigation system. Results show that the proposed system gives an accurate and reliable navigation solution even when the integer ambiguity is not correctly resolved and the cycle slip occurs.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.9
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• pp.736-744
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• 2003

The GPS attitude output or carrier phase observables can be effectively utilized to compensate the attitude error of the strapdown inertial navigation system. However, when the integer ambiguity is not correctly resolved and/or a cycle slip occurs, an erroneous GPS output can be obtained. If the erroneous GPS information is directly applied to the AGPS/INS integration system, the performance of the system can be rapidly degraded. This paper proposes an AGPS/INS integration system using the triple difference carrier phase observables. The proposed integration system contains a cycle slip detection algorithm, in which inertial information is combined. Computer simulations and van test were performed to verify the proposed integration system. The results show that the proposed system gives an accurate and reliable navigation solution even when the integer ambiguity is not correct and the cycle slip occurs.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.11
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• pp.563-571
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• 2003

In this paper, the control algorithm and control method for a combined system of shunt passive filter and series active filter in 3-phase 4-wire system are discussed. Moreover, the three-phase four-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and its 3th harmonics are termed as triple and zero sequence components that do not cancel each other in the system neutral. Consequently, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control algorithm for a series hybrid active system, whereas the control approach it adopts may directly influence its compensation characteristics. Hence, the advantage of this control algorithm is direct extraction of compensation voltage reference and the required rating of the series active filter is much smaller than that of a conventional shunt active filter. Some experiments were executed and experimental results from a prototype active power filter confirm the suitability of the proposed approach.