• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.144-154
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• 2004

In this paper we apply the space-time block codes (STBCs), the key technologies for the 4th generation mobile communication systems, to the OFDM system and analyze their performances. First, we derive the signal models for representative STBC schemes and demodulation procedures for each scheme. We also select the parameters for OFDM system considering mobile cellular environments and assign adequate modulation schemes to STBC-OFDM schemes according to the transmission rate from 2bps/Hz to 4bps/Hz. We finally compare and analyze the performances of STBC-OFDM schemes for the selected transmission rates through computer simulations, together with performance comparison when the same modulation scheme being adopted.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.437-440
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• 2009

We propose a fast stream cipher ASC16 for software implementation. ASC16 has a very simple structure with ASR(Arithmetic Shift Register), NLF(Non-Linear Filter), and NLB(Non-Linear Block), and is executed by a word. It is a stream cipher for wireless communication, which makes 32bit key streams using s-box with non-linear transformation. The processed result is almost same as SSC2, 32bit output stream cipher, developed by Zhang, Carroll, and Chan. The period is longer than SSC2, and it causes the difficulty of Correlation attack and raises security very much. The proposed ASC16 is efficiently used in the process of a fast cipher in the limited environment such as wireless communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1470-1476
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• 2020

This paper describes a design of a lightweight security system-on-chip (SoC) suitable for the implementation of security protocols for IoT and mobile devices. The security SoC using Cortex-M0 as a CPU integrates hardware crypto engines including an elliptic curve cryptography (ECC) core, a SHA3 hash core, an ARIA-AES block cipher core and a true random number generator (TRNG) core. The ECC core was designed to support twenty elliptic curves over both prime field and binary field defined in the SEC2, and was based on a word-based Montgomery multiplier in which the partial product generations/additions and modular reductions are processed in a sub-pipelining manner. The H/W-S/W co-operation for elliptic curve digital signature algorithm (EC-DSA) protocol was demonstrated by implementing the security SoC on a Cyclone-5 FPGA device. The security SoC, synthesized with a 65-nm CMOS cell library, occupies 193,312 gate equivalents (GEs) and 84 kbytes of RAM.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.2
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• pp.83-92
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• 2007

In connectionless packet network, if a sender encrypts packets by block chaining mode and send it to receiver, the receiver should decrypt packets in encrypted order that is not received order. Therefore, the performance and efficiency are lowered for crypto communication system. To solve this problem, we propose packet encryption scheme for connectionless packet network that can decrypt the packets independently, even if the received order of packets are changed or packets are missed. The scheme makes new IV(Initial Vector) using IV that created by key exchange process and salt that made by random number. We propose extended Cryptoki API that added packet encryption/decryption functions and mechanism for improving convenience and performance. We implement the scheme and get result that the performance increased about $1.5{\sim}l5.6$ times compare with in case of implementing using Cryptoki API in the test environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.7 no.2
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• pp.107-122
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• 1997

Most of the currently used electronic mail system has the threat of security such as illegal leak of message, forgery, uncertain identity, denial of sending and receiving, and so forth. The security for this system is not satisfied yet, thus we explore these problems. In this thesis, we implement the security services for internet mail system which cover the weakness for traditional mail system. This system provides not only security services which PEM and PGP provides (i.e message confidentiality, message integrity, originator authentication, non-repudiation of origin), but also message replay prevention. and non-denial of recipient using certification of contents. In addition, this system increases security of the digital signature by signing with signature block formatting on the creation of it. And it increases security of the digital enveloping by encrypting with encryption block formatting of message encryption key.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.6
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• pp.15-24
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• 2006

Recently, the importance of the area efficient implementation of cryptographic algorithm for the portable device is increasing. Previous ARIA(Academy, Research Institute, Agency) implementation styles that usually concentrate upon speed, we not suitable for mobile devices in area and power aspects. Thus in this paper, we present an area efficient AR processor which use 32-bit architecture. Using new implementation technique of diffusion layer, the proposed processor has 11301 gates chip area. For 128-bit master key, the ARIA processor needs 87 clock cycles to generate initial round keys, n8 clock cycles to encrypt, and 256 clock cycles to decrypt a 128-bit block of data. Also the processor supports 192-bit and 256-bit master keys. These performances are 7% in area and 13% in speed improved results from previous cases.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.21-28
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• 2009

In the recent years, power attacks were widely investigated, and so various countermeasures have been proposed, In the case of block ciphers, masking methods that blind the intermediate values in the algorithm computations(encryption, decryption, and key-schedule) are well-known among these countermeasures. But the cost of non-linear part is extremely high in the masking method of block cipher, and so the inversion of S-box is the most significant part in the case of AES. This fact make various countermeasures be proposed for reducing the cost of masking inversion and Zakeri's method using normal bases over the composite field is known to be most efficient algorithm among these masking method. We rearrange the masking inversion operation over the composite field and so can find duplicated multiplications. Because of these duplicated multiplications, our method can reduce about 10.5% gates in comparison with Zakeri's method.

• Geomechanics and Engineering
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• v.33 no.6
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• pp.553-565
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• 2023

As the structure of broken rock mass is complex, with obvious discontinuity and anisotropy, it is generally necessary to reinforce broken rock mass using grouting in underground construction. The purpose of this study is to experimentally investigate the mechanical properties of broken rock mass after grouting reinforcement with consideration of the characteristics of broken rock mass (i.e., degree of fragmentation and shape) and a range of reinforcement methods such as relative strength ratio between the broken rock mass and cement-based grout stone body (λ), and volumetric block proportion (VBP) representing the volumetric ratio of broken rock mass and the overall cement grout-broken rock mass mixture after the reinforcement. The experimental results show that the strength and deformation of the reinforced broken rock mass is largely determined by relative strength ratio (λ) and VBP. In addition, the enhancement in compressive strength by grouting is more obvious for broken rock mass with spherical shape under a relatively high strength ratio (e.g., λ=2.0), whereas the shape of rock mass has little influence when the strength ratio is low (e.g., λ=0.1). Importantly, the results indicate that columnar splitting failure and inclined shear failure are two typical failure modes of broken rock mass with grouting reinforcement.

• Korean Journal of Remote Sensing
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• v.40 no.1
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• pp.9-18
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• 2024

Small streams, despite their rich ecosystems, face challenges in vegetation assessment due to the limitations of traditional, time-consuming methods. This study presents a groundbreaking approach, combining unmanned aerial vehicles(UAVs), convolutional neural networks(CNNs), and the vegetation differential vegetation index (VDVI), to revolutionize both assessment and management of stream vegetation. Focusing on Idong Stream in South Korea (2.7 km long, 2.34 km² basin area)with eight diverse revetment methods, we leveraged high-resolution RGB images captured by UAVs across five dates (July-December). These images trained a ResNeXt101 CNN model, achieving an impressive 89% accuracy in classifying vegetation cover(soil,water, and vegetation). This enabled detailed spatial and temporal analysis of vegetation distribution. Further, VDVI calculations on classified vegetation areas allowed assessment of vegetation vitality. Our key findings showcase the power of this approach:(a) TheCNN model generated highly accurate cover maps, facilitating precise monitoring of vegetation changes overtime and space. (b) August displayed the highest average VDVI(0.24), indicating peak vegetation growth crucial for stabilizing streambanks and resisting flow. (c) Different revetment methods impacted vegetation vitality. Fieldstone sections exhibited initial high vitality followed by decline due to leaf browning. Block-type sections and the control group showed a gradual decline after peak growth. Interestingly, the "H environment block" exhibited minimal change, suggesting potential benefits for specific ecological functions.(d) Despite initial differences, all sections converged in vegetation distribution trends after 15 years due to the influence of surrounding vegetation. This study demonstrates the immense potential of UAV-based remote sensing and CNNs for revolutionizing small-stream vegetation assessment and management. By providing high-resolution, temporally detailed data, this approach offers distinct advantages over traditional methods, ultimately benefiting both the environment and surrounding communities through informed decision-making for improved stream health and ecological conservation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.5
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• pp.833-840
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• 2024

Existing side-channel analysis studies have mostly been analyzed only on block ciphers without considering the operation mode. However, establishing a methodology of side-channel analysis on operation mode is necessary because information for performing analysis varies depending on that. This paper proposes a methodology of correlation power analysis (CPA) on an operation mode CBC in a software target. The first round SubBytes layer output is generally used as a sensitive hypothetical intermediate value of an encryption algorithm AES (advanced encryption standard); however, the adversary should acquire the plaintext and ciphertext to calculate the input of AES in CBC mode. We propose an intermediate value calculated only by ciphertext. Besides, the initial vector (IV) could be treated as closed information in practice, although it is theoretically not secret. The adversary cannot decrypt the first block of plaintext without IV even if he analyzes the secret key. We propose a deep learning-based IV analysis method in a non-profiled environment.