• KIPS Transactions on Software and Data Engineering
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• v.4 no.5
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• pp.231-240
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• 2015

Medical imagery require to protect the privacy with preserving the quality of the original contents. Therefore, reversible watermarking is a solution for this purpose. Previous researches have focused on general imagery and achieved high capacity and high quality. However, they raise a distortion over entire image and hence are not applicable to medical imagery which require to preserve the quality of the objects. In this paper, we propose a novel reversible watermarking for medical imagery, which preserve the quality of the objects and achieves high capacity. First, object and background region is segmented and then predicted error histogram-based reversible watermarking is applied for each region. For the efficient watermark embedding with small distortion in the object region, the embedding level at object region is set as low while the embedding level at background region is set as high. In experiments, the proposed algorithm is compared with the previous predicted error histogram-based algorithm in aspects of embedding capacity and perceptual quality. Results support that the proposed algorithm performs well over the previous algorithm.

• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.30-38
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• 2002

Disordered carbon and boron-substituted disordered carbons $C_{l-x}B_x(x=0.05,\;0.10,\;0.20)$ were synthesized by Pyrolysis of LPG(liquid Propane gas)and $BCl_3$. Their electrochemical properties as anode materials for Li-ion secondary batteries were then investigated. When PVDF is added to the sample in a weight ratio 5 : 95, the disordered carbon with x=0.00 had the first discharge capacity 374 mAh/g. Its cycling performance was relatively good from the second cycle and it had the discharge capacity 258 mAh/g at the 10th cycle. When PVDF is added to the sample in a weight ratio 5 : 95, the sample with x=0.05 among the samples $C_{l-x}B_x(x=0.05,\;0.10,\;0.20)$ exhibited the largest first discharge capacity 860 mAh/g and discharge capacity 181 mAh/g at the 10th cycle. All the samples had similar cycling performances from the second cycle. The sample $C_{0.90}B_{0.10}$ showed the best electrochemical properties as a anode materials fur Li-ion secondary battery from the view points of the first discharge capacity(853 mAh/g when $10w1.\%$ PVDF is used), cycling performance, discharge capacity(400mAh/g at the 10th cycle when $10wt.\%$ PVDF is used). All the samples showed generally larger charge and discharge capacities when $10wt.\%$ PVDF ratter than $5wt.\%$ PVDF is used. The plateau region in the range of voltage lower than 1.25V becomes larger probably since the structure becomes less disordered by the addition of boron. When boron is added, the charge and discharge capacities decreased suddenly at the second cycle. This may be become only a part of Li are reversibly deintercalated and intercalated and a part of Li which are strongly combined with B are not deintercalated. The increases in charge and discharge capacities are considered to be resulted from the increase in the potential of Li in the boron-added carbons, caused by the strengthening of the chemical bond between the intercalated Li and the boron-carbon host since the boron acts as electron acceptor.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.449-453
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• 2007

Synthesis of Sn-GIC (Graphite intercalated compound) and its electrochemical characteristics were investigated to find a method for enhancing the performance of carbon anode of lithium ion battery. The content of Sn intercalated in graphite interlayer increased with increase of concentration of $SnCl_2$ solution and increase of the heat treatment temperature of dried graphite after dipped in $SnCl_2$ solution, respectively. And initial discharge capacity increased upon increase of intercalated Sn content. Sn-GIC with excellent electrochemical performance, which can be synthesized by heat treatment at $900^{\circ}C$ after dipped in 1.0 M $SnCl_2$ solution, showed 356 mAh/g of initial discharge capacity and 13% of capacity decay after 10 cycles.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.319-332
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• 2014

Insertion loss is used as the character to express the efficiency of EMI filter. In this paper, we studied the better method that can measure the insertion loss of EMI filter exactly than the original method. For the achievement of this, the method measuring both common mode(CM) and differential mode(DM) insertion loss with arbitrary input/output impedance is accomplished using a 4-ports S-parameters system for consideration of unbalanced factor. Using this method, when input/output used in specific system is known, CM/DM insertion loss of EMI filter inserted in the system can be calculated. Finally, we applied 4-ports modeling method to 'X/Y capacitor part' and suggested the algorithm for selecting suitable the value of Y-capacitor using mixed mode S-parameters and mixed mode chain S-parameters.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.145-150
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• 2010

In this paper, we propose additional data transmission system for spectrum efficiency improvement and derive channel capacity formula as a approximated closed-form. Spread spectrum watermarking scheme is selected for the watermarking embedder. Nakagami-q (Hoyt) model is considered as a multipath fading channel. Numerical results show the channel capacity variation of the proposed system in wireless fading channel. From the results, we confirm that the channel capacity of the watermarking system is affected by the fading coefficient and system parameters such that host sampling frequency, host-to-watermark ratio, watermark-to-noise ratio, and PN sequence length.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.32-37
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• 2004

The charge/discharge capacity of natural graphite anode in lithium secondary batteries was examined as a function of charge/discharge rate. When the natural graphite anode was galvanostatically cycled in the range of 0.0-2.0V $(vs.\;Li/Li^+)$, the charging capacity decreased with an increase in the charging rate, which is caused by an earlier approach to the charging cut-off (0.0 V) before the complete charging that is in turn caused by an ever-increasing overpotential at higher rates. Even if the overpotential of discharging reaction also increased at higher discharge rates, the discharging reaction took place in the range of 0.0-0.3 V that is far below the discharge cut-off (2.0 V). As a result, the discharge capacity was not affected by the discharge rate because all the lithium ions once intercalated are fully discharged even at high current condition. As the overpotential of lithium deposition reaction also increased at high current condition, the charge capacity of natural graphite could be enlarged by lowering the charging cut-off voltage below 0.0 V, There is, however, a limitation for the lowering of cut-off voltage because the resistance for lithium deposition is smaller than that of lithium intercalation into graphite. When the charge cut-off voltage was lowered down to -0.04 V under IC condition, lithium ions were inserted into graphite without lithium deposition such that the discharge capacity could be raised up to $11\%$.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.283-284
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• 2024

디지털 워터마킹은 디지털 컨텐츠에 정보를 삽입하는 기술이다. 종래의 디지털 워터마킹 기술은 견고성과 비가시성 사이에 트레이드오프 관계를 가지고, 변형 및 노이즈 공격 등에 취약하다. 본 논문에서는 호스트 이미지의 비가시성을 보장하면서 효율적인 공격 탐지와 소유자 식별이 가능한 워터마킹 기법을 제안한다. 제안한 방식은 주파수 분할 기반의 계층적 워터마킹 및 공격 탐지 시그니처 삽입을 통해 비가시성을 보장하며 용량과 견고성 측면에서 종래의 방법보다 향상된 성능을 보였다. 실험 결과에 따르면 종래의 디지털 워터마크가 무력화되는 왜곡 공격 상황에서 공격 탐지 시그니처 검출이 가능하여 워터마크 공격을 탐지하고 소유자를 식별할 수 있었다.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.5
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• pp.9-15
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• 2017

In the Digital Age, All Data used in the Internet is Digitized and Transmitted and Received Over a Communications Network. Therefore, it is Important to Transmit Data with Confidentiality and Integrity, Since Digital Data may be Tampered with and Tampered by Illegal users. Steganography is an Efficient Method for Ensuring Confidentiality and Integrity Together with Encryption Techniques. I Propose a Hangul Steganography Method that Inserts a Secret Message based on a Changing Insertion Position and a Changing Eojeol Size in a Cover Medium. Considering the Insertion Capacity of 3.35% and the File Size Change of 0.4% in Hangul Text Steganography, Experimental Results Show that the Jaro_score Value needs to be Maintained at 0.946.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.7
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• pp.684-694
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• 2000

For designing circuits for low power systems, the capacitance is an important factor for the power dissipation. Since the capacitance of a gate is proportional to the area of the gate, we can reduce the total power consumption of a circuit by reducing the total area of gates, where total area is a simple sum of all gate areas in the circuit. To reduce the total area, transistor resizing can be used. While resizing transistors, inserting buffer in the proper position can help reduce the total area. In this paper we propose two methods for concurrent transistor sizing and buffer insertion. One method uses template window simulation and the other uses extrapolation. Experimental results show that concurrent transistor sizing with buffer insertion achieved 10-20% more reduction of the total area than when it was done without buffer insertion and template window simulation is more efficient than extrapolation.

• Journal of Broadcast Engineering
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• v.8 no.3
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• pp.268-277
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• 2003

In this paper, we propose a new video watermarking method exploiting the human visual system (HVS) to find effective locations. in the video frames which make the watermark robust and imperceptible simultaneously. In particular, we propose a new HVS-optimized weighting map for hiding the watermark by considering HVS in three different aspects : frequency, spatial, and motion masking effects. The global masking map is modeled by combining the frequency masking, the spatial masking, and the motion masking. In this paper, we use a watermark which is generated by the bitwise exclusive-OR operation between a logo image and a random sequence. The amount of watermarks is weighted by a control parameter. Furthermore, we embed the watermark in the uncompressed video sequence for the general watermarking method available to various coding schemes. Simulation results show that the watermark is imperceptible and the proposed method is good for watermark capacity. It is also demonstrated that the proposed method is robust against various attacks, such as MPEG coding, MPEG re-encoding, and frame attacks.