• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.1
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• pp.44-53
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• 2023

Adversarial attacks have received great attentions for their capacity to distract state-of-the-art neural networks by modifying objects in physical domain. Patch-based attack especially have got much attention for its optimization effectiveness and feasible adaptation to any objects to attack neural network-based object detectors. However, despite their strong attack performance, generated patches are strongly perceptible for humans, violating the fundamental assumption of adversarial examples. In this paper, we propose a camouflaged adversarial patch optimization method using military camouflage assessment metrics for naturalistic patch attacks. We also investigate camouflaged attack loss functions, applications of various camouflaged patches on army tank images, and validate the proposed approach with extensive experiments attacking Yolov5 detection model. Our methods produce more natural and realistic looking camouflaged patches while achieving competitive performance.

• Journal of Educational Research in Mathematics
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• v.20 no.1
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• pp.85-102
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• 2010

Linear programming(LP) is useful for finding the best way in a given condition for some list of requirements represented as linear equations. This study analysed LP in mathematics contexts and LP in school mathematics contexts, considered learning process of LP from an epistemological point of view, and explored a hypothetical learning trajectory of LP. The differences between mathematics contexts and school mathematics contexts are whether they considered that the convex polytope $\Omega$ is feasible/infeasible or bounded/unbounded or not, and whether they prove the theorem that the optimum is always attained at a vertex of the polyhedronor not. And there is a possibility that students could not understand what is maximum and minimum of a linear function when the domain of the function is limited. By considering these three aspects, we constructed hypothetical learning trajectory consisted of 4 steps. The first step is to see a given linear expression as linear function, the second step is to partition a given domain by straight lines, the third step is to construct the conception of y-intercept by relating lines and the range of k, and the forth step is to identify whether there exists the optimum in a given domain or not.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1239-1251
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• 1999

In this paper a scalable QoS-based hierarchical inter-domain routing scheme for distributed multimedia applications in a high speed wide area network. The problem of QoS-based routing is formulated as a multicriteria shortest path problem, known as NP-complete[21,30]. Our routing scheme consists of two phases. In Phase 1, two graph construction algorithms are performed to model the network under consideration as a graph. The graph contains a part of the network topology which is completely neglected or partially considered by existing routing schemes, thus maintaining more accurate topology information. In Phase 2, a heuristic call-by-call algorithm is performed for selecting a feasible path efficiently in depth first search-like manner on the graph and tailoring to each application's QoS requirements, beginning at a vertex that represents the source node. In this paper, a simple rule is also produced, by which the visiting order of outgoing edges at each vertex on the graph is determined. The rule is based on each edge's the minimum normalized slackness to the QoS requested. The proposed routing scheme extends the PNNI-type hierarchical routing framework. Note that our routing scheme is one of a few QoS-based hierarchical routing schemes that address explicitly the issue of selecting a path with multiple metrics.

• Strategy21
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• s.45
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• pp.116-147
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• 2019

Despite the fact that South Korea, one of peninsula countries, has been already a middle power in an international arena, it still tends to get stuck in continental-driven inertia and be reluctant to become a consolidated maritime power. In its efforts to deal with the parable of South Korea, designing a tailored-made strategy needs to be initiated in detail. Its design is centered around two variables: classification of waters and prestige. First of all, the domain of waters confronted to South Korea ranges from the greatest threat to scattered national interest. Second, South Korea is prestigiously regarded as the middle power which is equipped with the capability to see beyond its sovereign waters. The Maritime Access Strategy(MAS) can be more clearly explained by three-axis factors: ends, ways, and means. Ends need to be oriented to achieving three types of classified objectives-Deterrence, Engagement around the world to maximize remotely-scattered interest and Check of neighboring countries' seapower expansion, called DEC. Ways is mainly driven by the closer access to three different types of waters: waters of security, check, and interest. The active access and closer approach to the domain of waters need to be maintained with a high degree of willingness and capability. Means is attainable by guiding naval forces to be armed with multiple platforms and functionally-balanced assets. These platforms and assets will allow the naval forces to attain and maintain cost effective means, leading to making MAS feasible. This strategy allows the middle-power Korea to make the best of its maritime assets at various seas, contributing to international stability as well as national security and interest.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.1
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• pp.128-138
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• 2010

In this paper, we propose a new bit assignment scheme for Wyner-Ziv video coding. Distributed video coding (DVC) is a new video coding paradigm which enables greatly low complexity encoding because it does not have any motion prediction module at encoder. Therefore, it is very well suited for many applications such as video communication, video surveillance, extremely low power consumption video coding, and other portable applications. Theoretically, the Wyner-Ziv video coding is proved to achieve the same rate-distortion (RD) performance comparable to that of the joint video coding. However, its RD performance has much gap compared to MC-DCT-based video coding such as H.264/AVC. Moreover, Transform Domain Wyner-Ziv (TDWZ) video coding which is a kind of DVC with transform module has difficulty of exact bit assignment because the entire image is treated as a same message. In this paper, we propose a feasible bit assignment algorithm using adaptive quantization matrix selection for the TDWZ video coding. The proposed method can calculate suitable bit amount for each region using the local characteristics of image. Simulation results show that the proposed method can enhance coding performance.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.212-219
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• 2017

As an environmental pollution and global warming due to an excessive carbon emission are intensified, the importance of renewable energy is in rise today. TCP (Tidal Current Power), one of the renewable energy sources, generates electricity by converting kinetic energy of current into rotational energy of turbine. Also the TCP has a great advantages of predictability and reliability. Because the generating power is proportional to cubic of stream velocity, amplifying current speed by applying duct is highly effective to increase the generating power. SPM (Single Point Mooring) can be applied for the weather vane with various current direction and also augments generating power of the system. In addition, simple installation and retrieval could be a merit of SPM system. By combining duct and SPM, TCP system for relatively low-speed-current and shallow water region can be feasible and economical. In this study, single point moored duct-type TCP system was designed and the motion of submerged structure was investigated in both numerical and experimental method. DNV wadam V4.8-1 and OrcaFlex 10.0a were used for the frequency and time domain motion analysis of system respectively. Duct model scaled by 0.05 of Froude conformity ratio and CWC (Circulate Water Channel) are used for experiment.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.627-634
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• 2008

This paper presents an optimum mixture design method for proportioning a concrete. In the proposed method, the search space is constrained as the domain defined by the minimal convex region of a database, instead of the available range of each component and the ratio composed of several components. The model for defining the search space which is expressed by the effective region is proposed. The effective region model evaluates whether a mix-proportion is effective on processing for optimization, yielding highly reliable results. Three concepts are adopted to realize the proposed methodology: A genetic algorithm for the optimization; an artificial neural network for predicting material properties; and a convex hull for evaluating the effective region. And then, it was applied to an optimization problem wherein the minimum cost should be obtained under a given strength requirement. Experimental test results show that the mix-proportion obtained from the proposed methodology using convex hulls is found to be more accurate and feasible than that obtained from a general optimum technique that does not consider this aspect.

• Smart Structures and Systems
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• v.16 no.2
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• pp.295-328
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• 2015

In recent years the monitoring of structural behavior through acquisition of vibrational data has become common practice. In addition, recent advances in sensor development have made the collection of diverse dynamic information feasible. Other than the commonly collected acceleration information, Global Position System (GPS) receivers and non-contact, optical techniques have also allowed for the synchronous collection of highly accurate displacement data. The fusion of this heterogeneous information is crucial for the successful monitoring and control of structural systems especially when aiming at real-time estimation. This task is not a straightforward one as measurements are inevitably corrupted with some percentage of noise, often leading to imprecise estimation. Quite commonly, the presence of noise in acceleration signals results in drifting estimates of displacement states, as a result of numerical integration. In this study, a new approach based on a time domain identification method, namely the Unscented Kalman Filter (UKF), is proposed for correcting the "drift effect" in displacement or rotation estimates in an online manner, i.e., on the fly as data is attained. The method relies on the introduction of artificial white noise (WN) observations into the filter equations, which is shown to achieve an online correction of the drift issue, thus yielding highly accurate motion data. The proposed approach is demonstrated for two cases; firstly, the illustrative example of a single degree of freedom linear oscillator is examined, where availability of acceleration measurements is exclusively assumed. Secondly, a field inspired implementation is presented for the torsional identification of a tall tower structure, where acceleration measurements are obtained at a high sampling rate and non-collocated GPS displacement measurements are assumed available at a lower sampling rate. A multi-rate Kalman Filter is incorporated into the analysis in order to successfully fuse data sampled at different rates.

• The Transactions of the Korea Information Processing Society
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• v.4 no.6
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• pp.1550-1556
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• 1997

In this paper, we apply the evolutionary algorithm to the combinatorial optimization problem. Evolutionary algorithm useful for the optimization of the large space problem. This paper propose a method for the reuse of wastes of light water in atomic reactor system. These wastes contain several reusable elements, and they should be carefully selected and blended to satisfy requirements as an input material to the heavy water atomic reactor system. This problem belongs to an NP-hard like the 0/1 knapsack problem. Two evolutionary strategies are used as approximation algorithms in the highly constrained combinatorial optimization problem. One is the traditional strategy, using random operator with evaluation function, and the other is heuristic based search that uses the vector operator reducing between goal and current status. We also show the method which perform the feasible test and solution evaluation by using the vectored knowledge in problem domain. Finally, We compare the simulation results of using random operator and vector operator for such combinatorial optimization problems.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.45-53
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• 2013

Fuel cell power system is one of the most promising energy source for the alternative energy because it has unique advantages such as high energy density, no power drop during operation, and feasible to make compact size. However, due to very low response time, fuel cell is difficult to correspond to drastic load changes and start-up operation. For solving these problem, fuel cell power system must include energy storage device such as Li-Poly battery or super capacitor. Therefore, bi-directional DC-DC converter must be required for this storage device and fuel cell-PCS control. This paper presents a design and modeling of the bi-directional DC/DC converter. Firstly, we present modeling the boost and buck mode of the bi-directional converter through both PWM switch model and state space averaging technique. Secondly, in order to minimize output ripple and transient response overshoot, we have two identical DC-DC converters interleaved and adopt two-loop voltage-current controller. The proposed bi-directional DC-DC converter's modeling method and control design have been verified with computer simulation and experimentation.