• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.214-220
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• 2006

In this paper, we propose the transmit power controlled adaptive modulated OFDM with frequency symbol spreading and equalization(TPC-AMS/FSS-OFDM) system. In the transmitter of the TPC-AMS/FSS-OFDM, each SP transformed signal is spread by orthogonal spreading codes and combined, so the detected signals obtain the same SINR(signal interference to noise ration) for each frequency symbol spreading block. In this case, we can assign the same modulation level and transmit power for each frequency symbol spreading block. Thus, the proposed system provides the increased throughput performance with reducing the total transmit power, FBI and MLI.

• ETRI Journal
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• v.28 no.5
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• pp.684-687
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• 2006

In this letter, we evaluate the system performance of a space-time block coded (STBC) multicarrier (MC) DS-CDMA system over a time selective fading channel, with imperfect channel knowledge. The average bit error rate impairment due to imperfect channel information is investigated by taking into account the effect of the STBC position. We consider two schemes: STBC after spreading and STBC before spreading in the MC DS-CDMA system. In the scheme with STBC after spreading, STBC is performed at the chip level; in the scheme with STBC before spreading, STBC is performed at the symbol level. We found that these two schemes have various channel estimation errors, and that the system with STBC before spreading is more sensitive to channel estimation than the system with STBC after spreading. Furthermore, derived results prove that a high spreading factor (SF) in the MC DS-CDMA system with STBC before spreading leads to high channel estimation error, whereas for a system with STBC after spreading this statement is not true.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.23-36
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• 2016

We propose a new type of OFDM-CDMA scheme which allows large inter-user timing offset using zero correlation zone(ZCZ) code in conjunction with block spreading technique. Moreover to maximize spectral efficiency, the proposed OFDMA does not have guard time(GT). This is opposite to the trends in the conventional schemes where GT are supposed to be larger to allow larger inter-user timing offset. It is remarkable that the proposed GT-free OFDM-CDMA scheme completely cancels inter-user interference in the multipath fading simply by despreading process. This inter-user interference-free feature still remains even there exist inter-user timing offsets as large as multiple OFDM symbols. Although the self-user interference exists due to no GT, it can be effectively suppressed by simple successive interference cancellation(SIC) from the first symbol in spread block as it is free from inter symbol interference(ISI).

• The Korean Journal of Pain
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• v.7 no.1
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• pp.116-118
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• 1994

Neurolytic splanchnic nerve block is effective for treatment of intractable upper abdominal cancer in. The possibility of neurologic complication cannot be completely precluded. A 53 year-old female patient with hepatoma and lung metastasis was submitted for splanchnic nerve block with alcohol. Splanchnic nerve block was performed under radiologic control by image intensifier without any difficulty during procedure. One day after the block, she complained of numbness with sensory deficit in bilateral inguinal area. Neurologic examination revealed that asymmetrical anesthesia, hypoesthesia at $T_{12}-L_2$. She was discharged 70 days after the block with partial improvement. The possibility of alcohol spreading to the low theracic and upper lumbar somatic nerves cannot be excluded.

• The Korean Journal of Pain
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• v.19 no.2
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• pp.181-186
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• 2006

Background: Although cervical epidural block can be a useful therapeutic treatment for head, neck and upper extremities pain, there is no consensus regarding the volume of injection required for pain management. Herein, the spreading in the vertebral segments after a cervical epidural injection of either a 5 or 10 ml volume was studied. Methods: A total of 78 patients, suffering from head, neck and upper extremity pain, were selected. Cervical epidural blocks were performed consecutively with 5 ml (n = 42) and 10 ml (n = 36) of 0.4% mepivacaine and 222 mg I/ml iopamidol at the C7⁣-T1 levels. Both anteroposterior (AP) and lateral radiographs were obtained under fluoroscopy, and the upper and lower epidural spreading of the contrast media in relation to the vertebral level was evaluated. Results: The cervical epidural blocks were performed without complications. The rostral spreading of the contrast media in the vertebral segments in groups 1 and 2 were $5.6{\pm}1.1$ and $6.1{\pm}1.1$, respectively. The caudal spreading of the contrast media in the vertebral segments in groups 1 and 2 were $5.4{\pm}3.4$ and $7.2{\pm}3.9$, respectively. The total numbers of segments with vertebral spreading of the contrast media in both directions showed significant differences between the two groups. The numbers of patients who showed spreading of the contrast media up to C2 vertebral segment showed no significant differences between the two groups. Conclusions: 5 and 10 ml epidural injection volumes may be adequate for the spread of contrast media to the entire cervical spine. A 5 ml epidural injection volume, compared to a 10 ml volume, may be ample when considering the possibility of unnecessary caudal spreading of drugs and volume related complications in the management of head, neck and upper extremity pain.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.423-429
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• 2019

Recently, a variety of methods for the performance improvement of ultra-high speed wideband wireless transmission systems have been suggested. This paper proposes a space-frequency (SF) block coded single side band (SSB) single carrier (SC)-frequency division multiple access (FDMA) transmission system. In the proposed SSB SC-FDMA system, SF block code is implemented with the complex conjugates, which are formed from discrete Fourier transform (DFT) spreading of pulse amplitude modulation (PAM) signals. As a result, transmit diversity gain can be obtained in the proposed SF block coded SSB SC-FDMA system without any significant increase of the system computational complexity. The simulation result shows that the signal-to-noise power ratio (SNR) performance of the proposed SF block coded SSB SC-FDMA system is approximately 4 dB better than the SNR performance of the conventional SSB SC-FDMA system with single transmit antenna at a symbol error rate (SER) of $10^{-2}$.

• Advances in Computational Design
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• v.7 no.4
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• pp.345-369
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• 2022

Infectious disease emergency hospitals are usually temporarily built during the pneumonia epidemic with higher requirements regarding diagnosis and treatment efficiency, hygiene and safety, and infection control.This study aims to identify how the Building Information Modeling (BIM) + Industrialized Building System (IBS) approach could rapidly deliver an infectious disease hospital and develop site epidemic spreading algorithms. Coronavirus-19 pneumonia construction site spreading algorithm model mind map and block diagram of the construction site epidemic spreading algorithm model were developed. BIM+IBS approach could maximize the repetition of reinforced components and reduce the number of particular components. Huoshenshan Hospital adopted IBS and BIM in the construction, which reduced the workload of on-site operations and avoided later rectification. BIM+IBS integrated information on building materials, building planning, building participants, and construction machinery, and realized construction visualization control and parametric design. The delivery of Huoshenshan Hospital was during the most critical period of the Coronavirus-19 pneumonia epidemic. The development of a construction site epidemic spreading algorithm provided theoretical and numerical support for prevention. The agent-based analysis on hospital evacuation observed "arched" congestion formed at the evacuation exit, indicating behavioral blindness caused by fear in emergencies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.248-256
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• 2007

In this paper, we propose a selective DFT spreading method to solve a high PAPR problem in uplink OFDMA system. A selective characteristic is added to the DFT spreading, so the DFT spreading method is mixed with SLM method. However, to minimize increment of computational complexity, differently with common SLM method, our proposed method uses only one DFT spreading block. After DFT, several copy branches are generated by multiplying with each different matrix. This matrix is obtained by linear transforming the each phase rotation in front of DFT block. And it has very lower computational complexity than one DFT process. For simulation, we suppose that the 512 point IFFT is used, the number of effective sub-carrier is 300, the number of allowed sub-carrier to each user's is 1/4 and 1/3 and QPSK modulation is used. From the simulation result, when the number of copy branch is 4, our proposed method has more than about 5.2 dB PAPR reduction effect. It is about 1.8 dB better than common DFT spreading method and 0.95 dB better than common SLM which uses 32 copy branches. And also, when the number of copy branch is 2, it is better than SLM using 32 copy branches. From the comparison, the proposed method has 91.79 % lower complexity than SLM using 32 copy branches in similar PAPR reduction performance. So, we can find a very good performance of our proposed method. Also, we can expect the similar performance when all number of sub-carrier is allocated to one user like the OFDM.

• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.139-153
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• 2018

The explosive interest in block chain, which was triggered by Bitcoin in 2009, is leading to substantial investment and the development of block chain technology. There is no dispute among experts that block chain will be the next generation of innovation. However, despite the high expectations for block chains, the related technology still has certain limitations. In addition to improving issues such as a low transaction throughput, inefficient agreement algorithms, and an inflexible governance structure, it is necessary to solve various problems for commercialization and full-scale spreading owing to the trilemma problem among the scalability, security, and decentralization. Under this situation, identification of the technology characteristics according to the generation is helpful for the development of the core technology requirements and commercialization blueprint in establishing an R&D direction. Therefore, in this article, the development of blockchain technology is divided into generations and analyzed in terms of the operational structure, consensus algorithm, governance, scalability, and security.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.110-118
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• 2009

The PB/MC-CDMA(Partial Block Multi Carrier Code Division Multilple Access) system can improve the performance by reducing the ICI(Inter-Code Interference) between users. Also, this system can achieve the frequency diversity gain by avoiding ISI(Inter Symbol Interference). Therefore, the performance of PB/MC-CDMA system is better than that of conventional MC-CDMA(Multi Carrier Code Division Multiple Access) system. However, similarly to other multi-carrier systems, it still has a PAPR(Peak to Average Power Ratio) issue. In this paper, we propose a peak power reduction technique involving optimized spreading code selection without side information for the PB/MC-CDMA. The PB/MC-CDMA system in each block of units reuses the code so the extra code will be remained. This extra code is divided into several groups to calculate the PAPR and solving the PAPR problem by transferring the selected code which has minimum peak power.