• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.7 no.2
• /
• pp.73-92
• /
• 1997

A modular exponentiation( E$M^{$=varepsilon$}$mod N) is one of the most important operations in Public-key cryptography. However, it takes much time because the modular exponentiation deals with very large operands as 512-bit integers. Modular exponentiation is composed of repetition of modular multiplications, and the number of repetition is the same as the length of the addition-chain of the exponent(E). Therefore, we can reduce the execution time of modular exponentiation by finding shorter addition-chain(i.e. reducing the number of repetitions) or by reducing the execution time of each modular multiplication. In this paper, we propose an addition-chain heuristics and two fast modular multiplication algorithms. Of two modular multiplication algorithms, one is for modular multiplication between different integers, and the other is for modular squaring. The proposed addition-chain heuristics finds the shortest addition-chain among exisiting algorithms. Two proposed modular multiplication algorithms require single-precision multiplications fewer than 1/2 times of those required for previous algorithms. Implementing on PC, proposed algorithms reduce execution times by 30-50% compared with the Montgomery algorithm, which is the best among previous algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.2
• /
• pp.738-756
• /
• 2020

The modular multiplication is the key module of public-key cryptosystems such as RSA (Rivest-Shamir-Adleman) and ECC (Elliptic Curve Cryptography). However, the efficiency of the modular multiplication, especially the modular square, is very low. In order to reduce their operation cycles and power consumption, and improve the efficiency of the public-key cryptosystems, a dual-field efficient FIPS (Finely Integrated Product Scanning) modular multiplication algorithm is proposed. The algorithm makes a full use of the correlation of the data in the case of equal operands so as to avoid some redundant operations. The experimental results show that the operation speed of the modular square is increased by 23.8% compared to the traditional algorithm after the multiplication and addition operations are reduced about (s² - s) / 2, and the read operations are reduced about s² - s, where s = n / 32 for n-bit operands. In addition, since the algorithm supports the length scalable and dual-field modular multiplication, distinct applications focused on performance or cost could be satisfied by adjusting the relevant parameters.

• Journal of Power Electronics
• /
• v.18 no.5
• /
• pp.1357-1368
• /
• 2018

In this paper, a novel high gain bidirectional modular dc-dc converter (BMC) with unipolar and bipolar structures for dc network interconnections is proposed. When compared with traditional dc grid-connecting converters, the proposed converter can achieve a high voltage gain with a simple modular transformerless structure. A sub-modular structure for the BMC is proposed to eliminate the unbalanced current stress between the different power units (levels) in the BMC. This can realize current sharing and standardized production and assembling. In addition, phase-interval operation is introduced to the sub-modules to realize low voltage and current ripple in both sides of the converter. Furthermore, two types of bipolar topologies of the sub-modular BMC were proposed to extend its application in bipolar dc network connections. In addition, the control system was optimized for grid-connection applications by providing various control strategies. Finally, simulations of a 3-level unipolar sub-modular BMC and a 4-level bipolar sub-modular BMC were conducted, and a 1-kW experimental 3-level unipolar prototype was developed to verify the effectiveness of the proposed converter.

• Journal of Korean Association for Spatial Structures
• /
• v.23 no.2
• /
• pp.45-52
• /
• 2023

Modular construction is an economical and efficient construction that reduces time and costs by manufacturing units in factories and constructing them on site. Currently, the demand for modular construction is increasing not only abroad but also domestically. As the demand for modular construction increases, a lot of development and research on connections between modular units are being conducted. Connections between modular units should be quick and simple to assemble when assembling units on site, and should be in a form that allows each unit to be connected regardless of direction. In addition, it must be able to exert sufficient strength against external loads. In this study, a connection between modular units using connecting steel plates and bolts was proposed, and the nonlinear behavior of the connection to external lateral force was analyzed through finite element analysis, and resistance performance was evaluated.

• Land and Housing Review
• /
• v.10 no.3
• /
• pp.67-75
• /
• 2019

The modular construction means that more than 70% of the parts such as walls, windows, electrical wiring, facility piping, bathrooms, and kitchen appliances are pre-assembled at the factory and transported to the site. It is possible to shorten the construction period than general construction work and to secure high quality through modular mass production since the modular construction works in the field at the same time as the modular production. However, there are only four domestic modular manufacturers, and each company's modular components and construction methods are different, so it is necessary to standardize them. Therefore, this study investigated the construction process centering on the stacking method of modular housing construction work applied to D site in Cheonan-si, and proposed the key points of quality management by construction stage. As the project was conducted as a pilot project for government R&D projects, some differences may occur from general modular housing construction. However, the construction process and quality control focus of each unit box type modular house analyzed in this study can be used as basic data in the future of modular housing construction. In addition, the results of this study can be used to establish construction standards, such as the development of checklists and establishment of standard processes.

• Bulletin of the Korean Mathematical Society
• /
• v.50 no.4
• /
• pp.1315-1328
• /
• 2013

We first derive several modular equations of degree 5 and present their concise proofs based on algebraic computations. We then establish explicit relations and formulas for some parameterizations for the theta functions ${\varphi}$ and ${\psi}$ by using the derived modular equations. In addition, we find specific values of the parameterizations and evaluate some numerical values of the Rogers-Ramanujan continued fraction.

• Bulletin of the Korean Mathematical Society
• /
• v.50 no.4
• /
• pp.1221-1233
• /
• 2013

We first derive some modular equations of degrees 3 and 9 and present their concise proofs based on algebraic computations. We then use these modular equations to establish explicit relations and formulas for the parameterizations for the theta functions ${\varphi}$ and ${\psi}$ In addition, we find specific values of the parameterizations to evaluate some numerical values of the cubic continued fraction.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.4
• /
• pp.376-380
• /
• 2008

This paper deals with a performance analysis of real-time control systems, which engages DMR(dual modular redundancy) to detect transient errors and checkpointing technique to tolerate transient errors. Transient errors are caused by transient faults and the most significant type of errors in reliable computer systems. Transient faults are assumed to occur according to a Poisson process and to be detected by a dual modular redundant structure. In addition, an equidistant checkpointing strategy is considered. The probability of the successful task completion in a real-time control system where periodic checkpointing operations are performed during the execution of a real-time control task is derived. Numerical examples show how checkpoiniting scheme influences the probability of task completion. In addition, the result of the analysis is compared with the simulation result.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.10a
• /
• pp.575-577
• /
• 2017

In public key cryptography such as RSA, modular exponentiation is the most time-consuming operation. RSA's modular exponentiation can be computed by repeated modular multiplication. To attain high efficiency for RSA, fast modular multiplication algorithms have been proposed to speed up decryption/encryption. Montgomery multiplication is limited by the carry propagation delay from the addition of long operands. In this paper, we propose a hardware structure that reduces the area of the Montgomery multiplication implementation for lightweight applications of RSA. Experimental results showed that the new design can achieve higher performance and reduce hardware area. A frequency of 884.9MHz and 250MHz were achieved with 84K and 56K gates respectively using the 90nm technology.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.11a
• /
• pp.163-164
• /
• 2012

Recently new construction system, the Infill Modular Construction System, is being emphasized depending on the industrialized technology introduction and the needs of high-rise housing. In order to applicate the Infill Modular Construction System and activate the domestic market, development of insufficient element technologies against the advanced technologies should be preceded and mobile device development of Infill Unit Module which is differentiated from the existing modular construction systems should be needed urgently. As advanced research for the activation of the Infill Modular Construction System, this research aims to develop Infill Unit Module's mobile device. This is expected to improve the constructability of Infill Unit Module. In addition development of mobile device considering weight of Infill Unit Module and construction errors are being planned.