• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.103-110
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• 2011

A widely used 3D face reconstruction method, structure from motion(SfM), shows robust performance when frontal, left, and right face images are used. However, this method cannot reconstruct a self-occluded facial part correctly when only one side view face images are used because only partial facial feature points can be used in this case. In order to solve the problem, the proposed method exploit a constrain that is bilateral symmetry of human faces in order to generate bilateral facial feature points and use both input facial feature points and generated facial feature points to reconstruct a 3D face. For quantitative evaluation of the proposed method, 3D faces were obtained from a 3D face scanner and compared with the reconstructed 3D faces. The experimental results show that the proposed 3D face reconstruction method based on both facial feature points outperforms the previous 3D face reconstruction method based on only partial facial feature points.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.91-96
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• 2011

In this paper, a low-power direct-conversion transmitter based on current-mode operation, which satisfies the IEEE 802.15.4 standard, is proposed and implemented in a $0.13{\mu}m$ CMOS technology. The proposed transmitter consists of DACs, LPFs, variable gain I/Q up-conversion mixer, a divide-by-two circuit with LO buffer, and a drive amplifier. By combining DAC, LPF, and variable gain I/Q up-conversion mixer with a simple current mirror configuration, the transmitter's power consumption is reduced and its linearity is improved. The drive amplifier is a cascode amplifier with gain controls and the 2.4GHz I/Q differential LO signals are generated by a divide-by-two current-mode-logic (CML) circuit with an external 4.8GHz input signal. The implemented transmitter has 30dB of gain control range, 0dBm of maximum transmit output power, 33dBc of local oscillator leakage, and 40dBc of the transmit third harmonic component. The transmitter dissipates 10.2mW from a 1.2V supply and the die area of the transmitter is $1.76mm{\times}1.26mm$.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.1-7
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• 2011

In this paper, we propose the digital image enhancement method including local tone reproduction and preservation of the hue. In recent studies, an integrated multi-scale retinex (IMSR) has produced great naturalness in the resulting images through enhancement of visibility in dark area in input images. However, most methods, including IMSR, work in RGB color spaces. As such, this produces hue distortion from the perspective of the human visual system, that is, hue distortion in CIELAB color space. Accordingly, this paper proposes an tone reproduction and enhancement of saturation method in a device-independent color space, CIELAB, to preserve the hue and obtain a high contrast and naturalness. First, to achieve the desired objectives, the IMSR is then applied to only the $L^*$ values in CIELAB color space, normalization, and simple mapping function, thereby preserving the balance of the color components and enhancement of visibility. Then, saturation adjustment is performed by applying the ratio of the chroma variation at the sRGB gamut boundary according to the corrected luminance. In experiments, the proposed method is shown to improve the visibility in dark shadows and bright regions in the resulting images and reduce any color distortion then preference test are performed.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.2
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• pp.94-101
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• 2012

This paper proposes an improved image steganalysis scheme to raise the detection rate of stego images out of cover images. To improve the detection rate of stego image in the steganalysis, tiny variation caused by data hiding should be amplified. For this, we extract feature vectors of cover image and stego image by two steps. First, we separate image into upper 4 bit subimage and lower 4 bit subimage. As a result, stego noise is expanded more than two times. We decompose separated subimages into twelve subbands by applying 3-level Haar wavelet transform and calculate co-occurrence probabilities of two different subbands in the same scale. Since co-occurrence probability of the two wavelet subbands is affected by data hiding, it can be used as a feature to differentiate cover images and stego images. The extracted feature vectors are used as the input to the multilayer perceptron(MLP) classifier to distinguish between cover and stego images. We test the performance of the proposed scheme over various embedding rates by the LSB, S-tool, COX's SS, and F5 embedding method. The proposed scheme outperforms the previous schemes in detection rate to existence of hidden message as well as exactness of discrimination.

• The Journal of Society for e-Business Studies
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• v.22 no.2
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• pp.169-185
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• 2017

Juliano Rizzo and Thai Duong, the authors of the BEAST attack [11, 12] on SSL, have proposed a new attack named CRIME [13] which is Compression Ratio Info-leak Made Easy. The CRIME exploits how data compression and encryption interact to discover secret information about the underlying encrypted data. Repeating this method allows an attacker to eventually decrypt the data and recover HTTP session cookies. This security weakness targets in SPDY and SSL/TLS compression. The attack becomes effective because the attacker is enable to choose different input data and observe the length of the encrypted data that comes out. Since Transport Layer Security (TLS) ensures integrity of data transmitted between two parties (server and client) and provides strong authentication for both parties, in the last few years, it has a wide range of attacks on SSL/TLS which have exploited various features in the TLS mechanism. In this paper, we will discuss about the CRIME and other versions of SSL/TLS attacks along with countermeasures, implementations. We also present direction for SSL/TLS attacks resistance in practice.

• Journal of Korea Water Resources Association
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• v.46 no.4
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• pp.345-359
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• 2013

In order to manage water quality efficiently and systematically through TMDL (Total Maximum Daily Load), the demand for the construction of spatial data for stream networks has increased for use with GIS-based water quality modeling, data management and spatial analysis. The objective of this study was to present an improved KRF (Korean Reach File) design as framework data for domestic stream networks to be used for various purposes in relation to the TMDL. In order to achieve this goal, the US EPA's RF (River Reach File) was initially reviewed. The improved design of the graphic and attribute data for the KRF based on the design of the EPA's RF was presented. To verify the results, the KRF was created for the Han River Basin. In total, 2,047 stream reaches were divided and the relevant nodes were generated at 2,048 points in the study area. The unique identifiers for each spatial object were input into the KRF without redundancy. This approach can serve as a means of linking the KRF with related database. Also, the enhanced topological information was included as attributes of the KRF. Therefore, the KRF can be used in conjunction with various types of network analysis. The utilization of KRF for water quality modeling, data management and spatial analysis as they pertain to the applicability of the TMDL should be conducted.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1264-1271
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• 2012

Fast tracking is important for high-speed data transmission in high-speed mobile environment such as high speed rail and vehicular. Digital retrodirective array antenna is possible to do automatically beam tracking because it can control the phase information of the output signal toward opposite direction to input signal without no a priori knowledge of the arrival direction. Also, Digital retrodirective array antennas has merit that it is easy to upgrade and modify compare with analogue retrodirective array antennas. In this paper, we analyze the BER performance of digital retrodirective array antenna under AWGN environment and multipath signal. Simulation results show correct phase estimation and conjugation of retrodirective array antenna by using phase detector block. Also, phase conjugation technique has better BER performance about 1 dB at source than that of without phase conjugation when phase lag is $15^{\circ}$ in AWGN environment. This paper also discusses effect of the presence of multipath signal. Phase and amplitude error about direction of direct signal occurs when retrodirective array system is affected by interference and multipath signal in the presence of multipath signal.

• Journal of the HCI Society of Korea
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• v.7 no.2
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• pp.25-34
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• 2012

A veterinary student learns and experiences veterinary processes though experiments and practices using real animals. However, animal protection laws regulate animal experiments and restrict number of the experiments on laboratory animals, veterinary students would have less chances of the experiments and the practices for their veterinary training with real animals. This paper proposes a simulator for veterinary education based on augmented reality (AR). We selected an intravenous injection procedure for the simulation because the injection procedure is the most frequently used procedure during veterinary training and the most difficult stage for beginning veterinary students. The proposed AR simulator provides with a tangible prop, of which shape looks like a leg of a real dog. It also has a injection simulator, which receives user's input and sends force feedbacks to indicate results of the injection simulation. We developed a WorkBench type AR system with an LED display and cameras for visual information processing. Finally, we evaluated its performance through experiments and user studies to check its acceptance level and usability of the proposed system. We compared the proposed system with a traditional video based education and an AR based system using a head mounded display (HMD). The results that the proposed system showed better performances over these systems.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.507-512
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• 2001

Feature-based similarity has become an important research issue in multimedia database systems. The features of multimedia data are useful for discriminating between multimedia objects. the performance of conventional multidimensional data structures tends to deteriorate as the number of dimensions of feature vectors increase. The $R^{*}-Tree$ is the most successful variant of the R-Tree. In this paper, we propose a SOM-based $R^{*}-Tree$ as a new indexing method for high-dimensional feature vectors. The SOM-based $R^{*}-Tree$ combines SOM and $R^{*}-Tree$ to achieve search performance more scalable to high-dimensionalties. Self-Organizingf Maps (SOMs) provide mapping from high-dimensional feature vectors onto a two-dimensional space. The map is called a topological feature map, and preserves the mutual relationships (similarity) in the feature spaces of input data, clustering mutually similar feature vectors in neighboring nodes. Each node of the topological feature map holds a codebook vector. We experimentally compare the retrieval time cost of a SOM-based $R^{*}-Tree$ with of an SOM and $R^{*}-Tree$ using color feature vectors extracted from 40,000 images. The results show that the SOM-based $R^{*}-Tree$ outperform both the SOM and $R^{*}-Tree$ due to reduction of the number of nodes to build $R^{*}-Tree$ and retrieval time cost.

• The KIPS Transactions:PartD
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• v.8D no.3
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• pp.295-304
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• 2001

The standards of a telephone Hangul keyboard should be decided in terms of objective factors : the number of strokes and fingers’moving distance. A number of designers will agree on them, because these factors can be calculated in an objective manner. So, We developed the model which can evaluate the efficiency of inputting Hangul on a telephone keyboard in terms of two factors. As compared with other models, the major features of this model are as follows : in order to evaluate the efficiency of Hangul input on a telephone keyboard, (1) this model calculated not a typing time but the number of strokes ; (2) concurrence frequency that had been counted on KOREA-1 Corpus was used directly ; (3) a total set of 67 consonants and vowels was used ; and (4) this model could evaluate a number of keyboards that use a kind of syllabic function key-the complete key, the null key and the final consonant key and also calculate a lot of keyboards that adopt no syllabic function key. However, there are many other factors to judge the efficiency of inputting Hangul on a telephone keyboard. If we want to make more accurate estimate of a telephone Hangul keyboard, we must consider both logical data and experimental data as well.