• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.1
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• pp.65-72
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• 2010

Nowadays, most hospitals have been used to create MRI or CT and managed them. Doctors depend on fast access to images such as magnetic resonance imaging (MRIs), computerized tomography (CT) scans, and X-rays for accurate diagnoses. Those image data are related privacy of a patient. Therefore, it should be protected from hackers and managed perfectly. In this paper, we propose a data hiding method into MRI or CT related a condition and intervention of a patient, and it is suggested that how to authenticate patient information from an image. In this way, we create hash code using HMAC with patient information, and hash code and patient information is hided into an image. After then, doctor will check authentication using HMAC. In addition, we use a reversible data hiding DE(Difference Expansion) algorithm to hide patient information. This technique is possible to reconstruct the original image with stego image. Therefore, doctor can easily be possible to check condition of a patient. As a consequence of an experiment with MRI image, data hiding, extraction and reconstruct is shown compact performance.

• Journal of Internet Computing and Services
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• v.23 no.2
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• pp.61-70
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• 2022

General users who use smartphone apps often use the Vault app to protect personal information such as photos and videos owned by individuals. However, there are increasing cases of criminals using the Vault app function for anti-forensic purposes to hide illegal videos. These apps are one of the apps registered on Google Play. This paper proposes a methodology for extracting feature points through XML-based keyword frequency analysis to explore Vault apps used by criminals, and text mining techniques are applied to extract feature points. In this paper, XML syntax was compared and analyzed using strings.xml files included in the app for 15 hidden Vault anti-forensics apps and non-hidden Vault apps, respectively. In hidden Vault anti-forensics apps, more hidden-related words are found at a higher frequency in the first and second rounds of terminology processing. Unlike most conventional methods of static analysis of APK files from an engineering point of view, this paper is meaningful in that it approached from a humanities and sociological point of view to find a feature of classifying anti-forensics apps. In conclusion, applying text mining techniques through XML parsing can be used as basic data for exploring hidden Vault anti-forensics apps.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.357-374
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• 2012

Considerable uncertainties are included in ground properties used for tunnel designs due to the limited investigation and tests. In this study, a back analysis was performed to find optimal ground properties based on artificial neural network using both face mapping data and convergence measurement data. First of all, the rock class of a study tunnel is determined from face mapping data. Then the possible ranges of ground properties were selected for each rock class through a literature review on the previous studies and utilized to establish more precise learning data. To find an optimal training model, a sensitivity analysis was also conducted by varying the number of hidden layers and the number of nodes more minutely than the previous study. As a result of this study, more accurate ground properties could be obtained. Therefore it was confirmed that the accuracy of the results could be increased by making use of not only convergence measurement data but also face mapping data in tunnel back analyses using artificial neural network. In future, it is expected that the methodology suggested in this study can be used to estimate ground properties more precisely.

• Proceedings of the Korean Statistical Society Conference
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• 2000.11a
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• pp.17-22
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• 2000

시계열 자료를 분석할 때 쉽게 접근하는 통계적 방법은 ARMA 모형이며 신경망 학습 방법 중에서는 다층 퍼셉트론에서의 Back-propagation 알고리즘이 일반적이다. Back-propagation을 비롯한 신경망 학습의 구조는 자료의 특성에 따라 경험적으로 결정하는 것으로 알려져 있다. 그러나 바로 이 점이 신경망 학습방법의 이용을 어렵게 하는 요인이기도 하다. 본 연구는 ARMA 모형 중 몇 개 유형의 자료에 대하여 Back-propagation 알고리즘을 적용함에 있어 어떠한 구조로 학습하는 것이 효율적인가를 입력층과 은닉층의 크기, 활성화 함수를 중심으로 검토하였다.

• Journal of KIISE:Software and Applications
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• v.28 no.4
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• pp.338-345
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• 2001

본 연구에서는 시계열자료를 예측하기 위해 적용한 n$\times$n$\times$1 신경망 구조에서 초기값의 시각적인 선택을 통한 개선된 학습과정을 제안한다. 적용된 Easton[1]의 제어상자는 시각적인 면과 실용적인 적용측면에서 다차원 구조를 논의하기에는 제한적이지만, 적은 개수의 은닉노드를 갖는 단순한 신경망구조에서는 초기 가중값들의 동적인 선택을 통하여 가능한 빨리 효과적인 학습이 이루어질 수 있게 할 수 있다. 신경망 학습의 오차 판단기준은 기존의 평균제곱오차(MSE)를 고려한다. 실증연구에는 모의생성된 ARMA(1,0) 자료와 담배생산량 자료를 이용한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.4
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• pp.74-81
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• 1997

This paper proposes an evolutionary learning algorithm to discipline the projection neural nctworks (PNNs) with special type of hidden nodes which can activate radial basis functions as well as sigmoid functions. The proposed algorithm not only trains the parameters and the connection weights hut also c~ptimizes the network structure. Through the structure optimization, the number of hidden node:; necessary to represent a given target function is determined and the role of each hidden node is decided whether it activates a radial basis function or a sigmoid function. To apply the algorithm, PNN is realized by a self-organizing genotype representation with a linked list data structure. Simulations show that the algorithm can build the PNN with less hidden nodes than thc existing learning algorithm using error hack propagation(EE3P) and network growing strategy.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.155-161
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• 2009

This paper proposes a high capacity data hiding method using modulus function of pixel-value differencing (PVD) and least significant bit (LSB) replacement method. Many novel data hiding methods based on LSB and PVD methods were presented to enlarge hiding capacity and provide an imperceptible quality. A small difference value for two consecutive pixels is belonged to a smooth area and a large difference one is located on an edge area. In our proposed method, the secret data are hidden on the smooth area by the LSB substitution method and PVD method on the edge area. From the experimental results, the proposed method sustains a higher capacity and still a good quality compared with other LSB and modified PVD methods.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.79-84
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• 2015

Steganography is to conceal the existence of secrete data itself. The Emulab is a framework to provide real systems and network topology that can set up at anytime by researchers. In this paper, we show that steganography techniques can be applied in the Emulab environment. Steganography methods are evaluated on a standalone and sharing environments using the color bitmap images. The cover image is divided into RGB channels and then embedded the secret data at each client. The experimental results demonstrate that execution time is better in client/server environment as cover image size is increasing.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1037-1041
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• 2006

본 연구에서는 수질자료에 내재되어 있는 주기성 및 경향성 등을 파악하기 위해 웨이블렛 변환을 적용하였으며 비선형 시계열자료에 대한 예측력이 우수한 인공신경망을 적용하여 예측모형을 개발하였다. 대상자료는 섬진강 유역의 주암호 수질자동측정망 지점에서 측정되고 있는 수질자료 중 2002년 1월 1일 ${\sim}$ 2004년 12월 31일까지의 일 TOC 수질자료를 이용하였다. 웨이블렛 변환을 위해 사용한 기저함수로는 Daubechies의 10번 웨이블렛 함수('db10')를 사용하였으며, 각 스케일링 및 웨이블렛 함수를 이용하여 5단계까지 변환하였다. 최종 변환된 근사성분과 D5, D4, D3, D2의 상세성분 자료를 이용하여 1시간후 TOC 예측 모형을 구성하였으며 그 결과 은닉층의 노드의 수가 17개인 모형인 Model_5_17 모형이 가장 우수한 예측력을 보였다.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.477-479
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• 2011

본 논문에서는 1차원 은닉 마코프 모델을 2차원으로 확장하기 위하여 노드들의 마코프 특성이 인과적인 관계를 갖는 마코프 메쉬 모델을 이용하여 완전한 2차원 HMM의 구조를 갖는 모델을 제안한다. 마코프메쉬 모델은 이웃시스템을 통하여 이전의 시점을 정의하고, 인과적인 관계를 통하여 전이확률의 계산을 가능하게 한다. 또한 영상의 최적의 분할을 위하여 계층적 디리슐레 과정을 사전분포로 두어 고정된 상태의 수가 아닌 무한의 상태 수를 갖는 2차원 HMM을 제안한다. HDP로 정의된 사전분포와 관측된 표본 자료의 정보를 갖는 우도함수를 결합한 사후분포의 베이스 추정은 깁스샘플링 알고리즘을 이용하여 계산된다.