• Journal of the Korea Society of Computer and Information
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• v.13 no.1
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• pp.21-27
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• 2008

The man who wants to create advance user created contents Is in need of using chroma-key method in a certain environment. Recently. pavilion that is painted with mono-color is used for the application of chroma-key. This paper aims to introduce a robust automatic adaptive chroma-key method without using pavilion. In this research. a new chroma-key method is applied to the separation of high frequency and low frequency using Wavelet is done in order that the noise can be eliminated. As a result, a chroma-key method with good capacity is shown from the research.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.1
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• pp.45-52
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• 2003

A number of stress corrosion cracks in turbine rotor disk keyway in power plants have been found and the necessity has been raised to detect and evaluate the cracks prior to the catastrophic failure of turbine disk. By ultrasonic RF signal analysis and using a neural network based on bark-propagation algorithm, we tried to evaluate the location, size and orientation of cracks around keyway. Because RF signals received from each reflector have a number of peaks, they were processed to have a single peak for each reflector. Using the processed RF signals, scan data that contain the information on the position of transducer and the arrival time of reflected waves from each reflector were obtained. The time difference between each reflector and the position of transducer extracted from the scan data were then applied to the back-propagation neural network. As a result, the neural network was found useful to evaluate the location, size and orientation of cracks initiated from keyway.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.05a
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• pp.157-158
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• 2018

IoT 환경에서는 다양한 센서 디바이스들이 각 디바이스들의 역할과 위치에 따라서 그룹 형태를 이루어 통신을 하게 된다. 그룹 형태의 센서 디바이스들이 통신하는 그룹 기반 통신에서는 수집된 정보를 게이트웨이와 같은 상위 디바이스에게 안전하게 전송해야 한다. 이 때 센서 디바이스들은 게이트웨이와의 인증 과정이 필요하며, 인증 후에 세션키를 분배하여 안전한 통신을 수행할 할 수 있다. 하지만, 일반적인 환경에서는 센서 디바이스의 수가 많아질수록 게이트웨이가 인증을 수행하고 키를 분배하기까지는 매우 큰 오버헤드가 발생하게 된다. 따라서 본 논문에서는 IoT 환경에서 그룹 기반 통신에 대한 보안 요구사항을 분석하고, 그룹 환경에서 사용될 수 있는 그룹 인증 기법에 대해 설계한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.6
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• pp.1319-1326
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• 2015

The symmetric key encryption algorithms, such as the AES or the ARIA, generate round keys by the key expansion mechanism. While the algorithm is executed, key expansion mechanism emits information about the secret key by the power consumption. The vulnerability exists that can reduce significantly the candidate of the secret key by the simple power analysis attack using a small number of the power traces. Therefore, we'll have to study about the attack and the countermeasure to prevent information leakage. While a simple power analysis attack on the AES key expansion has been studied since 2002, ARIA is insufficient. This paper presents a simple power analysis attack on 8-bit implementations of the ARIA-128 key expansion. The presented attack efficiently utilizes this information leakage to substantially reduce the key space that needs to be considered in a brute-force search for the secret key. We show that ARIA is vulnerable to a SPA attack based on hamming weight leakage.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.493-500
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• 2009

An ultrasonic signal processing algorithm was developed for extracting the information of cracks generated around the keyway of a turbine rotor disk. B-scan images were obtained by using keyway specimens and an ultrasonic scan system with x-y position controller. The B-scan images were used as input images for 2-Dimensional signal processing, and the algorithm was constructed with four processing stages of pre-processing, crack candidate region detection, crack region classification and crack information extraction. It is confirmed by experiments that the developed algorithm is effective for the quantitative evaluation of cracks generated around the keyway of turbine rotor disk.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.287-293
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• 2016

Wireless sensor networks (WSNs) have many applications and are deployed in a wide variety of areas. They are often deployed in potentially adverse or even hostile environment so that there are concerns on security issues in these WSNs. Recently, an anonymous user authentication and key agreement scheme (AUAKAS) was proposed based on symmetric cryptosystem in WSNs. It is claimed in AUAKAS that it assures security against different types of attacks including impersonation attacks. However, this paper shows that AUAKAS does not cope from user impersonation attack and gateway impersonation attack from the legally registered user on the gateway. The security analysis could guide the required features of the security scheme to be satisfied.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.868-870
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• 2002

기존의 네트워크 환경에서의 서비스와 달리 OSGi 프레임워크 환경에서의 서비스는 생명 주기에 따라 동적이고, 다른 서비스와의 상호작용 등이 일어나기 때문에 거짓 오퍼레이터(OP)에 의해 인증되지 않은 악의적인 서비스가 배치될 수 있고 또한 서비스가 변질 될 수도 있다. 그러므로, 개방형 서비스 게이트웨이 (OSG)를 시동하였을 때 초기화하는 과정인 부트스트랩핑(Bootstrapping)단계에서 공유 비밀키(shared secret)를 생성, 이로부터 유도된 MAC(Message Authentication Codes) Key를 기반으로 한 서비스 번들 인증을 통하여 안전한 서비스를 제공받을 수 있어야 한다. 본 논문에서는 서비스 번들을 인증 하기 위한 키 교환 방법과 서비스 인증 메커니즘을 제시하였다. 대칭키, 공개키의 키 교환 메커니즘은 대칭키를 이용한 키 교환 메커니즘이 공개키를 이용한 것보다 더 효율적이며, 이를 이용한 MAC 기반 서비스 번들 인증 또한 기존의 PKI 기반 서비스 번들 인증보다 인증 속도가 빠르다.

• The Inventors News
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• no.9
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• pp.13-13
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• 2003

유럽연합, 단일 특허법 제정키로 - 중국 화웨이 `시스코 지재권 침해 안했다` - 중국$\cdot$동남아 불법유통으로 수출부진 등 피해 극심

• The KIPS Transactions:PartB
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• v.8B no.5
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• pp.579-586
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• 2001

Digital watermarking is to embed imperceptible mark into image, video, audio, and text data to prevent the illegal copy of multimedia data. arbitrary modification, and also illegal sales of the copies without agreement of copyright ownership. In this paper, we study for the embedding and extraction of watermark key using wavelet in the luminance signal in order to implement the system to protect the copyright for image MPEG. First, the original image is analyzed into frequency domain by discrete wavelet transform. The RSA(Rivest, Shamir, Aldeman) public key of the coded target is RUN parameter of VLD(variable length coding). Because the high relationship among the adjacent RUN parameters effect the whole image, it prevents non-authorizer not to possess private key from behaving illegally. The Results show that the proposed method provides better moving picture and the distortion more key of insert than direct coded method on low-frequency domain based DCT.

• The Journal of the Korea Contents Association
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• v.21 no.7
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• pp.127-133
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• 2021

In industrial IoT environments, sensors generate data for their detection targets and deliver the data to IoT gateways. Therefore, managing large amounts of real-time sensor data is an essential feature for IoT gateways, and key-value storage engines are widely used to manage these sensor data. However, key-value storage engines used in IoT gateways do not take into account the characteristics of sensor data generated in industrial IoT environments, and this limits the performance of key-value storage engines. In this paper, we optimize the key-value storage engine by utilizing the features of sensor data in industrial IoT environments. The proposed optimization technique is to analyze the key, which is the input of a key-value storage engine, for further indexing. This reduces excessive write amplification and improves performance. We implement our optimization scheme in LevelDB and use the workload of the TPCx-IoT benchmark to evaluate our proposed scheme. From experimental results we show that our proposed technique achieves up to 21 times better than the existing scheme, and this shows that the proposed technique can perform high-speed data ingestion in industrial IoT environments.