• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1015-1022
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• 2012

This paper deals with hardware design which unifies MD5 and HAS-160 hash algorithms. Two algorithms get a message with arbitrary length and process message blocks divided into 512 bits each time and output a hash code with a fixed length. MD5 ouputs a hash code of 128 bits and HAS-160 a hash code of 160 bits. The unified hash core designed has 32% of slices overhead compared to HAS-160 core. However, there is only a fixed message buffer space used. The unified hash core which run a step in one clock cycle operates at 92MHz and has performance which digests a message in the speed of 724Mbps at MD5 and 581Mbps at HAS-160 hash mode. The unified hash core which is designed can be applicable to the areas such as E-commerce, data integrity and digital signature.

• The Journal of Society for e-Business Studies
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• v.5 no.1
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• pp.55-73
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• 2000

Recently; EC(Electronic Commerce) is increasing with high speed based on the expansion of Internet. EC which is done on the cyber space through Internet has strong point like independence from time and space. On the contrary, it also has weak point like security problem because anybody can access easily to the system due to open network attribute of Internet. Therefore, we need the solutions that protect the security problem for safe and useful EC activity. One of these solutions is the implementation of strong cipher algorithm. NC(Nonpolynomial Complete) cipher algorithm proposed in this paper is good for the security and it overcome the limit of current 64bits cipher algorithm using 128bits key length for input, output and encryption key, Moreover, it is designed for the increase of calculation complexity and probability calculation by adapting more complex design for subkey generation regarded as one of important element effected to encryption. The result of simulation by the comparison with other cipher algorithm for capacity evaluation of proposed NC cipher algorithm is that the speed of encryption and decryption is 7.63 Mbps per block and the speed of subkey generation is 2,42 μ sec per block. So, prosed NC cipher algorithm is regarded as proper level for encryption. Furthermore, speed of subkey generation shows that NC cipher algorithm has the probability used to MAC(Message Authentication Code) and block implementation of Hash function.

• Transactions of Materials Processing
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• v.18 no.2
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• pp.128-134
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• 2009

The present study covers an integrated simulation method to evaluate optical performance of an aspheric plastic lens by connecting an injection molding analysis with a ray tracing simulation. Traditional ray tracing methods have based on the assumption that the optical properties of a lens are homogeneous throughout the entire volume. This assumption is to a certain extent unrealistic for injection-molded plastic lenses because material properties vary at every point due to the injection molding effects. To take into account the effects of the inhomogeneous optical properties of the molded lens, a numerical scheme is developed to calculate the distribution of refractive index induced from the injection molding process. This index distribution is then reflected onto CODE $V^{(R)}$ simulation and used to calculate ray paths in inhomogeneous media. The proposed tracing scheme is implemented on the tracing of an aspheric lens for a mobile phone camera module.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1447-1454
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• 2006

The evaluation of parallel performance of a high speed impact simulation is not an easy task because not only the development of parallel explicit code is difficult but also a large number of processors is not easily accessible. In this paper, the parallel performance of a new Lagrangian FEM impact code carried out on cluster supercomputer has been described in high speed range. In the case of metal sphere impacting to oblique plate, the overall speed-up continuously increases even up to 128 CPUs. Investigation of elapsed time of each part reveals that most of the inefficiency comes from the load imbalance of contact.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.45-51
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• 2015

In this paper, we discuss the belief propagation decoding algorithm for polar codes. The performance of Polar codes for shorter lengths is not satisfactory. Motivated by this, we propose a novel technique to improve its performance at short lengths. We showed that the probability of messages passed along the factor graph of polar codes, can be increased by multiplying the current message of nodes with their previous message. This is like a feedback path in which the present signal is updated by multiplying with its previous signal. Thus the experimental results show that performance of belief propagation polar decoder can be improved using this proposed technique. Simulation results in binary-input additive white Gaussian noise channel (BI-AWGNC) show that the proposed belief propagation polar decoder can provide significant gain of 2 dB over the original belief propagation polar decoder with code rate 0.5 and code length 128 at the bit error rate (BER) of $10^{-4}$.

• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.123-128
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• 2010

This paper analyzes that the global positioning system (GPS) receiver differential code bias (DCB) has effect on the estimation the ionosphere total electron content (TEC). The data from nine permanent GPS sites of the Korea Astronomy and Space Science Institute (KASI) were used for the estimation of the receiver DCB before (Trimble 4000 SSi) and after (Trimble NetRS) the receiver replacement, using the singular value decomposition method. The results showed that the estimated mean value of the receiver DCB varied from 0.11 ns (nanosecond) to 7.54 ns before the receiver replacement, but the receiver DCBs shoed large values than 20 ns except some stations after the replacement. The receiver DCB showed a relatively large difference by types of the receivers, and, as a result, it had a great effect on the estimation the ionosphere TEC using GPS.

• Nuclear Engineering and Technology
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• v.38 no.2
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• pp.119-128
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• 2006

We start to develop a predictable technology for thermal-hydraulic performance of the RMWR core using an advanced numerical simulation technology. As a part of this technology development, we are developing the advanced interface tracking method to improve the conservation of volume of fluid. The present paper describes a part of the development of the twophase flow simulation code TPFIT with the advanced interface tracking method. The numerical results applied to large-scale water-vapor two-phase flow in tight lattice rod bundles are shown and compared with experimental results. In the results of numerical simulation, a tendency of the predicted void fraction distribution in horizontal plane agreed with the measured values obtained by the advanced neutron radiography technique including the bridge formation of the liquid at the position of adjacent fuel rods where an interval is the narrowest.

• Journal of Electrical Engineering and information Science
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• v.1 no.1
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• pp.118-128
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• 1996

In safety critical hard real-time systems, a timing fault may yield catastrophic results. In order to eliminate the timing faults from the fast responsive real-time control systems, it is necessary to schedule a code based on high precision timing analysis. Further, the schedulability enhancement by having multiple processors is of wide spread interest. However, although an instruction level parallel processing is quite effective to improve the schedulability of such a system, none of the real-time applications employ instruction level parallel scheduling techniques because most of the real-time scheduling models have not been designed for fine-grain execution. In this paper, we present a timing constraint model specifying high precision timing constraints, and a practical approach for constructing static schedules for a VLIW execution model. The new model and analysis can guarantee timing accuracy to within a single machine clock cycle.

• Korean Journal of Computational Design and Engineering
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• v.14 no.2
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• pp.122-128
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• 2009

The failure responses of adhesively bonded, hat stiffened structures are studied through numerical analysis using the finite element method. The responses are evaluated numerically for the bonded hat section/substrate structures containing different combinations of materials. It is studied what kind of material combinations causes the easier crack initiation in the structure. This study is conducted under plane strain conditions and J-integral via a commercial code ABAQUS as a total critical energy release criterion was used for observation on crack initiation. Also, the influence of adhesive on the structure is studied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1494-1502
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• 1992

이 논문에서는 디지털 영상 데이터의 가역 부호화 방법을 제안하였다. 정보원 모델을 위하여 인접 화소간의 차분을 이용한 차분모델과 마르코프 모델의 구성법을 보였다. 모델링에서 얻어지는 확률 구간의 변경을 이용한 다치 산술부호화의 고속화 알고리즘을 제시하였다. 제안방식의 성능을 계산량의 비교와 컴퓨터 시뮬레이션을 통하여 평가하였다. 그 결과 상태의 그룹화에 의한 차분모델이 기존의 여러방식에 비하여 적은 계산량으로 동등 이상의 평균부호 길이의 달성할 수 있어 효과적임을 알 수 있었다. 또한 제안한 고속화 방식은 차분모델에 적용이 용이하며 128계조를 갖는 영상에 있어서 평균 5배 이상의 고속효과를 얻었다.