• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권2호
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• pp.600-616
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• 2021

SIMON and SPECK are two families of lightweight block ciphers that have excellent performance on hardware and software platforms. At CRYPTO 2019, Gohr first introduces the differential cryptanalysis based deep learning on round-reduced SPECK32/64, and finally reduces the remaining security of 11-round SPECK32/64 to roughly 38 bits. In this paper, we are committed to evaluating the safety of SIMON cipher under the neural differential cryptanalysis. We firstly prove theoretically that SIMON is a non-Markov cipher, which means that the results based on conventional differential cryptanalysis may be inaccurate. Then we train a residual neural network to get the 7-, 8-, 9-round neural distinguishers for SIMON32/64. To prove the effectiveness for our distinguishers, we perform the distinguishing attack and key-recovery attack against 15-round SIMON32/64. The results show that the real ciphertexts can be distinguished from random ciphertexts with a probability close to 1 only by 2^8.7 chosen-plaintext pairs. For the key-recovery attack, the correct key was recovered with a success rate of 23%, and the data complexity and computation complexity are as low as 2⁸ and 2^20.1 respectively. All the results are better than the existing literature. Furthermore, we briefly discussed the effect of different residual network structures on the training results of neural distinguishers. It is hoped that our findings will provide some reference for future research.

• The Journal of the Acoustical Society of Korea
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• 제31권7호
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• pp.441-448
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• 2012

Spread spectrum provides the minimized inter-symbol interference, the low probability of intercept and the multiple access capability. This paper presents a direct sequence spread spectrum with carrier/timing recovery and equalizer which compensates the delay spread caused by multipath transmission. When the sea trials were performed in Korean East Sea, the bit error rates of QPSK and direct sequence spread spectrum are $1.46{\times}10^{-2}$ and $5.17{\times}10^{-4}$ at 3 km source-receiver range, respectively.

• Journal of KIISE:Information Networking
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• 제35권4호
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• pp.282-291
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• 2008

This paper focuses on message complexity performance analysis of MANET AAPs in reference to link errors generated by the mobile wireless nodes. To obtain the message complexity performance of AAPs in reference to the link error probability ($P_e$), an enhancement was made by proposing the retransmission limit (S) to be computed for error recovery (based on the link error probability), and then for each of the AAPs the control procedures for the retransmission limit have been properly included. The O-notation has been applied in analyzing the upper bound of the number of messages generated by a MANET group of N nodes. Based on a link error probability range of $P_e=0$ to 0.8, the AAPs investigated in this paper are Strong DAD, Weak DAD with proactive routing protocol (WDP), Weak DAD with on-demand routing protocol (WDO), and MANETconf. Based on the simulation results and analysis of the message complexity, for nominal situations, the message complexity of WDP was lowest, closely followed by WDO. The message complexity of MANETconf is higher than that of WDO, and Strong DAD results to be most complex among the four AAPs.

• Journal of the Society of Naval Architects of Korea
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• 제60권1호
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• pp.57-64
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• 2023

Recently, the increased use of anti-ship guided missiles, a weapon system that detects and attacks targets in naval engagement, has come to pose a major threat to the survivability of ships. In order to improve the survivability of ships in response to such anti-ship guided missiles, many studies of means to counteract them have been conducted in militarily advanced countries. The integrated survivability of a ship can be largely divided into susceptibility, vulnerability, and recoverability, and is expressed as the conditional probability, if the ship is hit, of damage and recovery. However, as research on susceptibility is a major military secret of each country, access to it is very limited and there are few publicly available data. Therefore, in this study, a possibility of estimating the susceptibility of ships using an anti-air defense system corresponding to anti-ship guided missiles was reviewed. To this, scenarios during engagement, weapon systems mounted to counter threats, and maximum detection/battle range according to the operational situation of the defense weapon system were defined. In addition, the effectiveness of the anti-air defense system and susceptibility was calculated based on the performance of the weapon system, the crew's ability to operate the weapon system, and the detection probability of the detection/defense system. To evaluate the susceptibility estimation feasibility, the sensitivity of the detailed variables was reviewed, and the usefulness of the established process was confirmed through sensitivity analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제29권7B호
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• pp.675-684
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• 2004

There have been several efforts to avoid unnecessary retransmission timeouts (RTOs), which is the main cause for TCP throughput degradation. Unnecessary RTOs can be classified into three groups according to their cause. RTOs due to multiple packet losses in the same window for TCP Reno, the most prevalent TCP version, can be avoided by TCP NewReno or using selective acknowledgement (SACK) option. RTOs occurring when a packet is lost in a window that is not large enough to trigger fast retransmit can be avoided by using the Limited Transmit algorithm. In this Paper, we comparatively analyze these schemes to cope with unnecessary RTOs by numerical analysis and simulations. On the basis of the results in this paper, TCP performance can be quantitatively predicted from the aspect of loss recovery probability. Considering that overall performance of TCP is largely dependent upon the loss recovery performance, the results shown in this paper are of great importance.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제38권3호
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• pp.39-48
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• 2015

In this study, granting the optimal loan limit on SME (Small and Medium Enterprise) loans of financial institutions was proposed using the traditional newsvendor model. This study was the first domestic case study that applied the newsvendor model that was mainly used to calculate the optimum order quantity under some uncertain demands to the calculation of the loan limit (debt ceiling) of institutions. The method presented in this study made it possible to calculate the loan limit (debt ceiling) to maximize the revenue of a financial institution using probability functions, applied the newsvendor model setting the order volume of merchandise goods as the loan product order volume of the financial institution, and proposed, through the analysis of empirical data, the availability of additional loan to the borrower and the reduction of the debt ceiling and a management method for the recovery of the borrower who could not generate profit. In addition, the profit based loan money management model presented in this study also demonstrated that it also contributed to some extent to the prediction of the bankruptcy of the borrowing SME (Small and Medium Enterprise), as well as the calculation of the loan limit based on profit, by deriving the result values that the borrowing SME (Small and Medium Enterprise) actually went through bankruptcy at later times once the model had generated a signal of loan recovery for them during the validation of empirical data. accordingly, The method presented in this study suggested a methodology to generated a signal of loan recovery to reduce the losses by the bankruptcy.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제38B권9호
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• pp.765-774
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• 2013

In this paper, we present a cooperative compressed spectrum sensing scheme for correlated signals in decentralized wideband cognitive radio networks. Compressed sensing is a signal processing technique that can recover signals which are sampled below the Nyquist rate with high probability, and can solve the necessity of high-speed analog-to-digital converter problem for wideband spectrum sensing. In compressed sensing, one of the main issues is to design recovery algorithms which accurately recover original signals from compressed signals. In this paper, in order to achieve high recovery performance, we consider the multiple measurement vector model which has a sequence of compressed signals, and propose a cooperative sparse Bayesian recovery algorithm which models the temporal correlation of the input signals.

• The Journal of Korean Medicine
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• 제30권1호
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• pp.83-94
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• 2009

Background and Objectives: The skin barrier protects skin against a harmful environment. Its function includes an antimicrobial barrier as well as a physical barrier. Stress is harmful to the skin barrier and there are many studies on this, but there are few about the effect of stress during pregnancy on the skin barrier of offspring. The aim of this study was to investigate the effect of stress during pregnancy on the skin barrier of offspring by examination with the naked eye, cortisol, weight, TEWL and histologic tests. Materials and Methods: Male hairless mice ten weeks old were coupled with females for three days. After twelve days the females were divided into two groups. We stressed one group and not the other group. The offspring from the non-stressed (N group) and stressed (S group) grew up until four weeks. The S group was exposed to chronic mild stress using the chronic stress model protocol modified method of Wilner and Towell for a week. We made examinations with the naked eye, assessment of cortisol, weight, TEWL, and histologic test to contrast the S group with the N group. Statistical analysis was performed by using Mann-Whitney and Friedman test. Statistical significance was achieved if the probability was less than 5% (p<0.05). Results: 1. By making an examination with the naked eye, S group showed papules, creases and dryness on their skin, but N showed no change compared with normal skin. 2. There was no statistically significant difference between S group and N group in cortisol (p>0.05). 3. There was no statistically significant difference between S group and N group in weight. N group had less weight than S group (p<0.05). 4. There was no statistically significant difference between S group and N group in TEWL (p>0.05). 5. There was no statistically significant difference between S group and N group in TEWL recovery (p>0.05). 6. In TEWL and TEWL recovery, there was statistically significant difference by time between S group and N group (p<0.005). Histologically, S group showed a thicker epidermis and epidermal crest than N group. Conclusions: We found that stress during pregnancy has negative effects on the skin barrier of offspring. Though there were no statistically significant differences between S group and N group in TEWL recovery, we found evidence that the recovery of skin barrier function is interrupted by stress during pregnancy by examination with both the naked eye and histology.

• Journal of Korean Society of Disaster and Security
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• 제16권2호
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• pp.85-98
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• 2023

Flood is one of the most frequent natural disasters worldwide. In Korea, the probability of urban flooding is greatly increasing due to complex factors such as global warming, an increase in impervious areas, and limitations in expanding water supply facilities in existing urban areas. However, large-scale civil engineering works to prevent urban inundation are socially and economically difficult to obtain national consent. Recently the importance of resilience, which is the ability to return to the original state after a disaster through rapid recovery while preparing for natural disasters to a level that the local community can afford socially and economically, is increasing. Accordingly, various studies on urban resilience have been conducted, but the resilience measurement method related to the lifeline that provides essential services of the city is insufficient. However, among lifelines, road networks are important facilities for the transportation of recovery resources and rapid recovery in the event of a natural disaster, so road networks are a major factor that must be considered when measuring the degree of recovery of a city in the field of natural disasters. Therefore, this study proposes a recovery evaluation method considering the characteristics of resilience and road networks in the urban flooding field and analyzes the effect of road networks on urban resilience.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.281-284
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• 2002

Error resilience for image coding is an important component of multimedia communication system. Error resilience schemes address loss recovery from the compression perspective. Multiple description coding (MDC) is one of the error resilience techniques promising for robust video transmission. It is the way to achieve tradeoff description such as scalar quantization, correlating transform and the quantized frame expansion. In this paper, we consider Multiple Description Scalar Quantization (MDSQ) to wavelet domain. Conventional MDSQ schemes considered description with equal weights in each sub-bands. But, we can see that the each sub-bands is unequal contribution to whole image quality. Therefore, we experiment the multiple design MDSQ table to make probability of zero index high, which gives high efficiency in arithmetic symbol coder. We also compare our proposed method with the conventional methods and show improved performance in terms of redundancy-rate-distortion.