• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.200-208
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• 2009

A macroblock layer rate control for H.264/AVC has the problem that allocated target bits for current frame occasionally are exhausted too fast due to inadequate quantization parameter assignment. In this case, the maximum permissible quantization parameter is used to encode for remaining macroblocks and it leads to degradation of the visual quality. In addition, the header bits length estimation algorithm used for quantization parameter assignment takes the average header bits length for the encoded macroblocks of the previous frame and the current frame. Therefore, it generates a big mismatch between the actually generated header bits length and the estimated header bits length. In this paper, we propose adaptive quantization parameter decision method to prevent early exhausting target bits during encoding the current frame by considering the number of macroblocks that have negative targets bits in previous frame and the improved header bits length estimation scheme for accurate quantization parameter decision.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.181-184
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• 2000

In this paper, we described a design of the input buffer system for efficiently dealing with MPEG audio bitstream to demux header and side information, audio data. In order to overcome the limitations of fixed-word manipulation in bitstream demuxing, we proposed a new variable length bit retrieval system with FSM sequencer supporting MPEG audio frame format, and serial buffer demuxing audio stream, FIFO circular buffer including header and side information.

• Design & Manufacturing
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• v.13 no.4
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• pp.10-16
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• 2019

Semiconductor chip is bonded to the substrate by melting solder bumps. In general, the chip bonding is applied by a Reflow process or a Thermo-Compression(TC) bonding process. In this paper, we introduce a Laser Assisted Thermo-Compression bonding (LATCB) process to improve the anxiety of the existing process(Reflow, TC bonding). In the LATCB process, the chip is bonded to the substrate by irradiating a laser with a uniform energy density in the same area as the chip to melt only the solder bumps and press the chip with a Transparent Compression Module (TCM). The TCM consists of a fused silica header for penetrating the laser and pressurizing the chip, and a piezoelectric actuator (P.A.) coupled to both ends of the header for micro displacement control of the header. In addition, TCM is a structure that can pressurize the chip and deliver it to the chip and solder bumps without losing the energy of the laser. Fused silica, which is brittle, is vulnerable to deformation, so the header may be damaged when an external force is applied for pressurization or a displacement differenced is caused by piezoelectric actuators at both ends. On the other hand, in order to avoid interference between the header and the adjacent chip when pressing the chip using the TCM, the header has a notch at the bottom, and breakage due to stress concentration of the notch is expected. In this study, the thickness and notch length that the header does not break when the external force (500 N) is applied to both ends of the header are optimized using structural analysis and Coulomb-Mohr failure theory. In addition, the maximum displacement difference of the P.A.s at both ends where no break occurred in the header was derived. As a result, the thickness of the header is 11 mm, and the maximum displacement difference between both ends is 8 um.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.469-479
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• 2009

The GEM frame is used a mean to deliver the variable length user data and consists of the header and the payload in the G-PON system. The HEC field of header protects contents of the header and is used to maintain GEM frame synchronization at the same time. When an LCDG (Loss of GEM Channel Delineation) occurs while receiving frames, the receiver have to discard corrupted frames until acquiring the synchronization again. Accordingly, high-speed synchronization method is required to minimize the frame loss. In this paper, we suggest not only a main state machine but a sub-state machine to reduce the frame loss when undetectable errors occurred in the GEM header. Also, we provide a more efficient and fast parallel structure to detect the starting point of the header. Finally, the proposed method is implemented with the FPGA and verified by the logic analyzer.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.2
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• pp.49-60
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• 1999

IC 카드의 하드웨어적인 제약으로 대부분의 IC 카드는 대칭키 알고리즘을 사용하고 있지만 IC 카드 하드웨어 제조 기술의 발전으로 앞으로는 보안성이 우수한 비대 칭키 알고리즘이 많이 사용될 것이다. 그리고 IC 카드의 가장 큰 제약적 중 하나는 메모리 용량의 한계이다. 따라서 보안상 안전하면서도 메모리를 적게 사용하는 IC 카드 운영체제의 구현을 중요한 문제이다. 그래서 본 논문에서는 다양한 종류의 키 알고리즘을 수용할 수 있는 키 파일 탐색 기법을 제안하였다. 또한 데이터 파일 헤더에 잠금 필드를 삽입하여 보안성을 향상시켰으며 메모리 사용량을 줄일 수 있도록 데이터 파일 헤더만을 이용한 파일 탐색 기법과 자유 공간 탐색 기법을 제안하였다. Because of the evolution of IC card hardware fabrication technologies IC card will be able to accept asymmetric key encryption algorithm in the future. One of the most restrictive points of IC card is memory capacity. Therefore it is an important problem to design a secure IC card operating system using memory in small. In this paper we proposed a key file search mechanism using a key length field inserted in a key file header structure. The key file search mechanism makes IC card execute any key-based encryption algorithm. In addition we proposed inserting a lock field in data file header structure. The lock field intensifies the security of a data file. Finally we proposed a data file search mechanism and free space search mechanism using only data file header. The file system using these mechanisms spends smaller memory than that using a file description table and record of unallocated space.

• Journal of the Korean Society of Safety
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• v.39 no.3
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• pp.14-19
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• 2024

Hydrogen is one of the most popular eco-friendly energy sources for reducing global warming. To use hydrogen as a conventional fuel, liquid hydrogen plants should introduce waste hydrogen treatment processes. A major safety issue of liquid hydrogen plants is choosing the most suitable purge gas to use in case of an accident. A purge gas prevents the formation of explosive mixed gases in the vent header. In general, nitrogen is the main purge gas used in chemical plants. Nitrogen has a freezing point of -210℃, which is higher than the boiling point of hydrogen. Helium, with a freezing point lower than hydrogen, is instead recommended as a purge gas of the vent header during hydrogen liquefaction. However, helium is roughly 100 times more expensive than nitrogen. To address this issue, this study uses simulations to investigate safe conditions for introducing nitrogen as the purge gas during hydrogen liquefaction. The temperature change from the safety valve to the vent header is evaluated when the external temperature of the safety valve discharge pipe is at 5℃, 10℃, and 20℃. Additionally, the most optimal length for a discharge pipe according to pipe diameter is investigated.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1359-1365
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• 2008

The portion of header in H.264 gets higher than those of previous standards instead of its better compression efficiency. Therefore, this paper proposes a new technique to compress the header of H.264. Unifying a sentence elementary in H.264, H.264 does not consider the distribution of element which be encoded and uses existing Exp-Golomb method, but it is uneffective for variable length coding. Most of the header are block type(s) and motion vector difference(s), and there are redundancies in the header of H.264. The redundancies in the header of H.264 which are analyzed in this paper are three. There are frequently appearing symbols and non-frequently appearing symbols in block types. And when mode 8 is selected in macroblock, all of four sub-macroblock types are transferred. At last, same values come in motion vector difference, especially '0.' This paper proposes the algorithm using type code and quadtree, and with them presents the redundant information of header in H.264. The type code indicates shape of the macroblock and the quadtree does the tree structured motion compensation. Experimental results show that proposed algorithm achieves lower total number of encoded bits over JM12.4 up to 32.51% bit reduction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.1
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• pp.117-124
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• 1998

As window sized increases, the throughput input-buffered packet switch with a window scheme improves on random traffic condition. However, the improvement diminishes quickly under bursty traffic. In this paper, we propose Burst Head Addressable FIFO mechanism and memory structure having search capability in unit of burst header to compensate the sensitiveness of the windowed scheme to bursty traffic. The performance of a input-buffered switch using the proposed Burst Header Addressable FIFO input buffer was analyzed using computer simulations. The maximum throughput of the conventional FIFO scheme approaches an asymptotic value 0.5 as mean burst length increases. The maximum throughput of the proposed scheme is greater than that of the conventional scheme for any mean burst length and window size.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.490-492
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• 2018

This paper presents an analysis of the AMR speech data as a basic work to study the technique of inputting and transmitting AMR voice data which is widely used in the public cell phone. AMR consists of HEADER and Speech Data, and it is transmitted in bit format and has 8 bit-rate modes in total. HEADER contains mode information of Speech Data, and the length of Speech Data differs depending on the mode. We chose the best mode which is best to input into QR code and analyzed that mode. It is a goal to show a higher compression ratio for voice data by the analysis and experiments. This analysis shows improvement in that it can transmit voice data more effectively.

• Review of KIISC
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• v.17 no.2
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• pp.9-23
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• 2007

The air interface supports a security layer which provides the key exchange protocol, authentication protocol, and encryption protocol. The authentication is performed on the encryption protocol packet. The authentication protocol header or trailer may contain the digital signature that is used to authenticate a portion of the authentication protocol packet that is authenticated. The encryption protocol may add a trailer to hide the actual length of the plaintext of padding to be used by the encryption algorithm. The encryption protocol header may contain variables such as the initialization vector (IV) to be used by the encryption protocol. It is our aim to firstly compute the session key created from the D H key exchange algorithm, and thereof the authenticating key and the encryption key being generated from the session key.