• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.59-65
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• 2012

In this paper, we investigate the compressed sensing (CS) algorithms for modeling a super-resolution near-field structure (super-RENS) disc system with a sparse Volterra filter. It is well known that the super-RENS disc system has severe nonlinear inter-symbol interference (ISI). A nonlinear system with memory can be well described with the Volterra series. Furthermore, CS can restore sparse or compressed signals from measurements. For these reasons, we employ the CS algorithms to estimate a sparse super-RENS read-out channel. The evaluation results show that the CS algorithms can efficiently construct a sparse Volterra model for the super-RENS read-out channel.

• The Korean Journal of Nuclear Medicine
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• v.39 no.3
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• pp.182-190
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• 2005

Purpose: There are differences between Standard Uptake Value (SUV) of CT attenuation corrected PET and that of $^{137}Cs$. Since various causes lead to difference of SUV, it is important to know what is the cause of these difference. Since only the X-ray CT and $^{137}Cs$ transmission data are used for the attenuation correction, in Philips GEMINI PET/CT scanner, proper transformation of these data into usable attenuation coefficients for 511 keV photon has to be ascertained. The aim of this study was to evaluate the accuracy in the CT measurement and compare the CT and $^{137}Cs$-based attenuation correction in this scanner. Methods: For all the experiments, CT was set to 40 keV (120 kVp) and 50 mAs. To evaluate the accuracy of the CT measurement, CT performance phantom was scanned and Hounsfield units (HU) for those regions were compared to the true values. For the comparison of CT and $^{137}Cs$-based attenuation corrections, transmission scans of the elliptical lung-spine-body phantom and electron density CT phantom composed of various components, such as water, bone, brain and adipose, were performed using CT and $^{137}Cs$. Transformed attenuation coefficients from these data were compared to each other and true 511 keV attenuation coefficient acquired using $^{68}Ge$ and ECAT EXACT 47 scanner. In addition, CT and $^{137}Cs$-derived attenuation coefficients and SUV values for $^{18}F$-FDG measured from the regions with normal and pathological uptake in patients' data were also compared. Results: HU of all the regions in CT performance phantom measured using GEMINI PET/CT were equivalent to the known true values. CT based attenuation coefficients were lower than those of $^{68}Ge$ about 10% in bony region of NEMA ECT phantom. Attenuation coefficients derived from $^{137}Cs$ data was slightly higher than those from CT data also in the images of electron density CT phantom and patients' body with electron density. However, the SUV values in attenuation corrected images using $^{137}Cs$ were lower than images corrected using CT. Percent difference between SUV values was about 15%. Conclusion: Although the HU measured using this scanner was accurate, accuracy in the conversion from CT data into the 511 keV attenuation coefficients was limited in the bony region. Discrepancy in the transformed attenuation coefficients and SUV values between CT and $^{137}Cs$-based data shown in this study suggests that further optimization of various parameters in data acquisition and processing would be necessary for this scanner.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.331-333
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• 2003

본 논문에서는 802.11을 기반으로 한 무선 링크에서 인터넷 상의 대표적인 전송계층 프로토콜인 TCP(Transmission Control Protocol)와 HDP(User Datagram Protocol)의 성능을 비교한다. 또한 이들 프로토콜이 무선 환경에서 보이는 문제점을 지적하고 원인을 분석한다. 무선 네트워크의 용량은 유선 네트워크와 다르며, 따라서 유선 네트워크 용량을 기반으로 설계된 TCP는 불안정하게 작동한다. 본 논문에서는 주목할만한 전송 프로토콜의 병목현상을 나타내는 원인으로 MAC(Medium Access Control)에 의해 채널을 잡기 위한 경쟁이 심각함과 전송 계층 프로토콜의 네트워크 용량 예측이 올바르지 않음을 지적하고, TCP와 HDP를 비교하여 무선 망에서도 네트워크 상황에 적응하는 기법이 중요함을 확인한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.746-755
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• 2014

Compressive sensing (CS) has drawn much interest as a new sampling technique that enables signals to be sampled at a much lower than the Nyquist rate. By noting that the block-based compressive sensing can still keep spatial correlation in measurement domain, in this paper, we propose a novel encoding technique for measurement data obtained in the block-based CS of natural image. We apply discrete wavelet transform (DWT) to decorrelate CS measurements and then assign a proper quantization scheme to those DWT coefficients. Thus, redundancy of CS measurements and bitrate of system are reduced remarkably. Experimental results show improvements in rate-distortion performance by the proposed method against two existing methods of scalar quantization (SQ) and differential pulse-code modulation (DPCM). In the best case, the proposed method gains up to 4 dB, 0.9 dB, and 2.5 dB compared with the Block-based CS-Smoothed Projected Landweber plus SQ, Block-based CS-Smoothed Projected Landweber plus DPCM, and Multihypothesis Block-based CS-Smoothed Projected Landweber plus DPCM, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.921-922
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• 2014

에너지 절약과 에너지 재생산 측면에 있어서 일상생활에서 낭비되고 있는 에너지를 다시 회수하여 재사용 할 수 있는 시스템은 경제적인 측면에서 그 가치가 높다고 할 수 있다. 이러한 관점에서 일반 주유소나 도장시설 등과 같은 환경에서 무심히 대기로 배출되는 휘발성 유증기를 포집하여 다시 에너지로 재사용하게 되면 경제적인 효과가 높다고 할 수 있다. 본 논문은 기존의 PLC 기반으로 동작하고 있는 휘발성유기화합물에 대한 액화장치(Liquefaction equipment)를 정보통신기술(Information & Communication Technology)을 접목시켜 액화장치를 효율적으로 관리하고, 내부 액화온도를 적절하게 제어하여 액화기의 효율을 향상시키고자 한다. 또한 액화기의 운전상태에 대한 정보를 ZigBee 기반의 무선 통신기술을 도입하여 원격지 관리서버로 액화기 상태정보를 전송하여 액화기에 대한 합리적인 운전 스케쥴 관리와 에너지 생산성을 높이고자 하며, 스마트기기로 모니터링 할 수 있도록 액화장치의 정보를 제공하고자 한다.

• KIISE Transactions on Computing Practices
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• v.23 no.4
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• pp.256-261
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• 2017

The notion of System of Systems (SoS), which is composed by many independent systems (i.e., Constituent Systems, CS), has emerged in various domains including social infrastructure. It is widely expected that complex requirements, which cannot be achieved in each CS-level, will be achieved in an SoS-level. While verification of SoS-level goal achievement is one of the most important problems, concrete case studies on SoS modeling and verification are still rare. In this paper, we focus on the fact that each CS performs an action for its own purpose by its own decision-making mechanism. We propose a novel Action-Benefit-Cost (ABC) SoS model which caters to the independent decision-making mechanisms of CSs. Using an abstract SoS example, this proposal provides a case study for the modeling and quantitative verification of the ABC SoS model.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.8
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• pp.7-12
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• 2010

In this paper, $C_{60}$ based Organic thin film transistor OTFTs) have been fabricated using BPhen(Bathophenanthroline) and BPhen doped with Cs interlayers between $C_{60}$ active layer and Al electrodes to improve the electrical performance. The addition of the BPhen layer resulted in enhanced performances by reducing surface roughness between organic-metal interface. And the contact resistance was reduced by using the BPhen doped with Cs interlayer with co-evaporation method. These performances suggests that the $C_{60}$ based OTFT with BPhen doped with Cs interlayer is a promising application in the fabrication of n-type organic transistors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.254-256
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• 2014

In this paper, using the Android App to remote database monitoring system is proposed. Existing remote database monitoring scheme CS(Client / Server) based. Conventional CS based systems are space constraints and a plurality of administrator to access the database at that degrade performance disadvantages. The advantage of the proposed system first, because the web -based interface allows the application program, and also the ease of maintenance, through a web browser, if you have Internet access anytime, anywhere environment without restrictions of time and space monitoring. Second, the proposed system because the App -based technology due to an increase in connection session and query execution does not affect the performance of your database. Third, if there is a problem with the remote database through which social networks immediately notify the administrator of the smartphone in real time so that the administrator can identify the problem.

• Annual Conference on Human and Language Technology
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• 2021.10a
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• pp.461-466
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• 2021

본 연구에서는 DECO(Dictionnaire Electronique du COreen) 한국어 전자사전과 LGG(Local-Grammar Graph)에 기반한 반자동 언어데이터 증강(Semi-automatic Symbolic Propagation: SSP) 방식에 입각하여, 핀테크 분야의 CS(Customer Service) 챗봇 NLU(Natural Language Understanding)을 위한 주석 학습 데이터를 효과적으로 생성하고, 이를 기반으로 RASA 오픈 소스에서 제공하는 DIET(Dual Intent and Entity Transformer) 아키텍처를 활용하여 핀테크 CS 챗봇 NLU 시스템을 구현하였다. 실 데이터을 통해 확인된 핀테크 분야의 32가지의 토픽 유형 및 38가지의 핵심 이벤트와 10가지 담화소 구성에 따라, DECO-LGG 데이터 생성 모듈은 질의 및 불만 화행에 대한 양질의 주석 학습 데이터를 효과적으로 생성하며, 이를 의도 분류 및 Slot-filling을 위한 개체명 인식을 종합적으로 처리하는 End to End 방식의 멀티태스크 트랜스포머 모델 DIET로 학습함으로써 DIET-only F1-score 0.931(Intent)/0.865(Slot/Entity), DIET+KoBERT F1-score 0.951(Intent)/0.901(Slot/Entity)의 성능을 확인하였으며, DECO-LGG 기반의 SSP 생성 데이터의 학습 데이터로서의 효과성과 함께 KoBERT에 기반한 DIET 모델 성능의 우수성을 입증하였다.

• Journal of IKEEE
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• v.20 no.4
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• pp.337-343
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• 2016

This study conducted the gamma ray spectroscopic analysis of the microcolumnar CsI:Tl deposited onto the SiPMs using thermal evaporation deposition. The SEM measured thickness of microcolumnar CsI:Tl and of its individual columns. From the SEM observation, the measured thickness of CsI:Tl were $450{\mu}m$ and $600{\mu}m$. The gamma ray spectroscopic properties of microcolumnar CsI:Tl, $450{\mu}m$ and $600{\mu}m$ thick deposited onto the SiPMs were analyzed using standard gamma ray sources $^{133}Ba$ and $^{137}Cs$. The spectroscopic analysis of microcolumnar CsI:Tl deposited onto the SiPMs included the measurements of response linearity over the $^{137}Cs$ gamma ray intensity; and gamma ray energy spectrum. Furthermore from the gamma ray spectrum measurement of $^{133}Ba$ and $^{137}Cs$, $450{\mu}m$ thick CsI:Tl showed good efficiency when measured with $^{133}Ba$ and $600{\mu}m$ thick CsI:Tl was highly efficient when measured with $^{137}Cs$.