• Journal of information and communication convergence engineering
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• v.11 no.1
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• pp.62-68
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• 2013

This paper proposes a method for identification of harmful video images based on the degree of harmfulness in the video content. To extract harmful candidate frames from the video effectively, we used a video color extraction method applying a projection map. The procedure for identifying the harmful video has five steps, first, extract the I-frames from the video and map them onto projection map. Next, calculate the similarity and select the potentially harmful, then identify the harmful images by comparing the similarity measurement value. The method estimates similarity between the extracted frames and normative images using the critical value of the projection map. Based on our experimental test, we propose how the harmful candidate frames are extracted and compared with normative images. The various experimental data proved that the image identification method based on the 2-dimensional projection map is superior to using the color histogram technique in harmful image detection performance.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.351-356
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• 2016

In recent years, as smartphones with Android platforms expand, the number of Android applications increases. Android applications implement Java and XML to compose the user interface, among other things. Between Java and XML, various problems may occur. Nonetheless, static analysis research and tools are not sufficient. In this paper we will list the problems which may occur between Java and XML. Subsequently, we will propose a detection method for them. Using the proposed technique, we found 172 Android-specific problems and 35 performance drop issues in 150 Android applications in the Google Play Store. We would like to contribute to research into static analysis and software quality improvement.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.4
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• pp.177-180
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• 2013

A software birthmark means inherent characteristics that can be used to identify a program. Because the software birthmark is difficult to remove by simple program transformation, it can be used to detect code theft. In this paper, we propose a birthmark technique based on API k-gram of Android applications. Android SDK provides various libraries that help programmers to develop application easily. In order to use Android SDK, we have to use API method calls. The API call instructions are hard to be replaced or removed, so they can be a inherent characteristics of an application. To show the effectiveness of the proposed birthmark, we compared it with previous birthmarks and evaluated it with open source applications. From the experiments, we verified that the credibility and resilience of our birthmark is higher than previous birthmarks.

• Annual Conference of KIPS
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• 2014.11a
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• pp.443-446
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• 2014

Code reuse attack (CRA)는 기존의 코드 내에서 필요한 코드 조각들 (gadgets)을 모아 indirect branch 명령어들로 잇는 방식으로 공격자가 원하는 악성 프로그램을 구성할 수 있는 강력한 공격 방법이다. 공격자는 자신의 코드를 대상 시스템에 심는 대신 기존의 코드를 이용하기 때문에, 대부분의 범용 운영체제 (OS)가 강제하는 W^X protection 을 무력화할 수 있다. 이러한 CRA 에 대응하기 위하여 다수의 연구들에서 branch 의 trace 를 분석하여 CRA 고유의 특성을 찾아내는 Signature 기반 탐지 기술을 제안하였다. 본 논문에서는 ARM 프로세서 상에서의 CRA 를 대응하기 위한 Signature 기반 탐지 기술을 효율적으로 도울 수 있는 binary 분석 및 meta-data 생성 기술을 제안한다. 특히, 본 논문은 우리의 이전 논문에서 고려 되지 못했던 ARM 의 두 가지 명령어 세트의 특성을 고려하여, 공격자가 어느 명령어 세트를 이용하여 CRA 를 시도하더라도 막아낼 수 있도록 meta-data 를 두 가지 mode 에 대해서 생성하였다. 실험 결과, meta-data 는 본래 바이너리 코드 대비 20.8% 정도의 크기 증가를 일으키는 것으로 나타났다.

• Journal of Power Electronics
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• v.18 no.1
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• pp.56-69
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• 2018

In this paper, an improved Space Vector Modulation (SVM) based fault tolerant operation on a nine-level Cascaded H-Bridge (CHB) inverter with an additional backup circuit is proposed. Any type of fault in a power converter may result in a power interruption and productivity loss. Three different faults on H-bridge modules in all three phases based on the SVM approach are investigated with diagrams. Any fault in an inverter phase creates an unbalanced output voltage, which can lead to instability in the system. An additional auxiliary unit is connected in series to the three phase cascaded H-bridge circuit. With the help of this and the redundant switching states in SVM, the CHB inverter produces a balanced output with low harmonic distortion. This ensures high DC bus utilization under numerous fault conditions in three phases, which improves the system reliability. Simulation results are presented on three phase nine-level inverter with the automatic fault detection algorithm in the MATLAB/SIMULINK software tool, and experimental results are presented with DSP on five-level inverter to validate the practicality of the proposed SVM fault tolerance strategy on a CHB inverter with an auxiliary circuit.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.517-518
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• 2007

A method to recognize unpaved road region using a 3D depth measurement system is proposed for mobile robots. For autonomous maneuvering of mobile robots, recognition of obstacles or recognition of road region is the essential task. In this paper, the 3D depth measurement system which is composed of a rotating mirror, a line laser and mono-camera is employed to detect depth, where the laser light is reflected by the mirror and projected to the scene objects whose locations are to be determined. The obtained depth information is converted into an image. Such depth images of the road region represent even and plane while that of off-road region is irregular or textured. Therefore, the problem falls into a texture identification problem. Road region is detected employing a simple spatial differentiation technique to detect the plain textured area. Identification results of the diverse situation of Nonlinear trail are included in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1484-1490
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• 2007

The Cross Reference Point(CRP) is a robust method for finding salient points in watermarking systems because it is based on the geometrical structure of a normalized image in order to avoid pointing error caused by digital attacks. After normalization of an image, the 100 CRPs are calculated. Next, the 100 blocks centered by CRPS are formed. These 100 blocks are arranged using a secrete key. Each boundary of 50 out of 100 blocks is surrounded by 8 blocks which are selected by the ordered number of a preceding block. This number is a seed of random number generator for selecting 8 out of 50 blocks. The search area of a center block is formed by a secrete key. The pixels of a center block are quantized to 10 levels by predefined thresholds. The watermarks are generated by the 50 quantized center blocks. These watermarks are embedded directly in the remaining 50 blocks. In other words, 50 out of 100 blocks are utilized to generate watermarks and the remaining 50 blocks are used to watermark embedding. Because the watermarks are generated in the given images, we can successfully detect watermarks after several digital attacks. The reason is that the blocks for the generation and detection of watermarks are equally affected by digital attacks except for the case of local distortion such as cropping.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.558-560
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• 2003

This paper examines the capability of remote sensing technique for detecting and quantifying the foliar nutrients of oil palm crop. Study has been carried out in the Malaysian Palm Oil Board (MPOB) Research Station in Kluang Johore, Malaysia. Result of the study shows a strong relationship between measured foliar nutrient and the spectral reflectance measured using spectroradiometer. Model that has been developed can be used to estimate the nutrient concentration in the oil palm plantation at micro level and also at macro -level using appropriate satellite data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.86-89
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• 2000

The detection technique both the polarization and the mobile charge density at the same time in ferroelectric films on Si using TVS method have been proposed. This method yields a polarizable and an ionic displacement current peaks whose areas are proportional to the total polarization reversal charge and the total moble ionic space charge, respectively. The calculated polarization and the mobile charge density were 0.42 [$\mu$C/$\textrm{cm}^2$] and 5.5$\times$10$^{11}$ (ions/$\textrm{cm}^2$) in the SBT film of MFIS structure measured at 25$0^{\circ}C$, and 1.4 [$\mu$C/$\textrm{cm}^2$] in the LiNbO$_3$ film of MFS structure measured at 30$0^{\circ}C$, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.683-683
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• 2012

영상 수위 계측 방법은 카메라와 목자판만으로 이루어진 비교적 간단한 시스템과 육안으로 수위를 직접 확인할 수 있다는 장점을 가지고 있으나 실제 하천에서 장기간 운영시 목자판이 하천수와 직접 접촉하면서 필연적으로 발생하는 오염, 훼손, 부유물 부착 및 걸림 등의 이유로 목자판의 시인성이 떨어지면서 수면을 정확히 인식하지 못하여 오측이 증가하는 문제점이 발생하였다. 본 연구는 이와 같은 기존 수면인식방법의 문제점을 해결하기 위하여 새로운 수면인식방법을 제안한다. 새로운 수면인식방법은 목자판 영역과 수역이 포함된 시차가 있는 두 장 이상의 연속적인 영상에서 유수의 이동, 바람에 의한 물결 등으로 인해 초래된 수역의 요동을 판단하여 수면을 인식하고 수위를 계측하는 방법이다. 이 방법의 성능을 검증하기 위하여 목자판이 오염된 경우에 대하여 실내 및 현장 실험을 실시하였다. 두 경우의 실험결과에서 모두 기존 수면인식방법에서는 오염된 부분을 수면으로 잘못 인식하였으나, 새로운 방법에서는 수면을 정확하게 인식하여 올바른 수위를 측정할 수 있었다. 따라서 새로운 수면인식방법을 이용하면 기존 수면인식방법보다 정확도를 향상시킬 수 있을 것이며, 홍수시 목자판에 부유물이 걸리거나 목자판이 일부 파손된 경우, 목자판이 다단으로 설치된 경우 등에서도 수면을 정확하게 인식할 수 있을 것으로 기대된다.