• The Journal of the Acoustical Society of Korea
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• v.17 no.3
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• pp.59-64
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• 1998

본 논문에서는 LSP 벡터 양자화의 성능에 대하여 분석하고 성능이 향상된 새로운 LSP 벡터 양자화 방법을 제안한다. 먼저, 10msec프레임 구조를 가지고 Moving Average 예측 필터를 사용한 LSP Split 벡터 양자화의 성능을 여러 훈련 방법과 벡터 Split 방법 및 Bit 할당 방법에 따라 비교한다. 다음, Split 벡터 양자화의 문제점을 해결하기 위하여 새로 운 Split 벡터 양자화 검색 방법을 제안한다. 스펙트럼 왜곡지수를 이용한 양자화 성능 측정 결과 새로 제안된 방법이 기존의 방법보다 우수한 양자화 성능을 보인다.

• Electronics and Telecommunications Trends
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• v.37 no.2
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• pp.1-10
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• 2022

Similar to present computers, quantum computers comprise quantum bits (qubits) and an operating system. However, because the quantum states are fragile, we need to correct quantum errors using entangled physical qubits with quantum error correction (QEC) codes. The combination of entangled physical qubits with a QEC protocol and its computational model are called a logical qubit and fault-tolerant quantum computation, respectively. Thus, QEC is the heart of fault-tolerant quantum computing and overcomes the limitations of noisy intermediate-scale quantum computing. Therefore, in this study, we briefly survey the status of QEC codes and the physical implementation of logical qubit over various qubit technologies. In summary, we emphasize 1) the error threshold value of a quantum system depends on the configurations and 2) therefore, we cannot set only any specific theoretical and/or physical experiment suggestion.

• The Korean Journal of Air & Space Law and Policy
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• v.26 no.1
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• pp.93-125
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• 2011

The International Civil Aviation Convention (Chicago Convention) has been a backbone of international air transport system whereby air transport between States should be based on bilateral agreements, and in particular, international airfares, which are set up through IATA(International Air Transport Association) rate-fixing machinery could be approved by the governments concerned. International airfares are fares for transporting passenger and freight and their conditions between two or more countries. However, since U.S. pursued th deregulation policy in 1978 whereby routes, capacity and fares could be freely determined by airlines, many States have been following so called open-skies agreements. In many cases, aeronautical and competent authorities have been reviewing whether airlines' commercial activities including air fares could possibly conflict with free competition rules envisaged in relevant laws and regulations. As competition among airlines gets intense, airlines often resort to cooperation with other airlines in the forms such as equity exchange, M&A, code-sharing, fares consultation and resource pooling, mainly with a view to effectively use resources available and to avoid monopoly situation resulting from excessive and destructive competition among players. Whereas bearing in mind that application of competition laws is important to secure consumers' interests by preventing airlines's malpractices such as bargaining exorbitant fares, it is also important to comprehensively consider as many factors as possible, from that unilateral measure by governments may bring about retaliatory measures by the governments affected, to that airlines' cooperative practices may rather increase consumers' benefits by lowering air fares.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.382-382
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• 2011

보다 저렴한 다결정 실리콘 웨이퍼를 사용한 다결정 실리콘 태양전지의 발전효율개선을 위해서는 태양광스펙트럼의 표면 흡수기구를 최적화하고, 전자-정공쌍의 생성극대화 및 재결합 기구 제어를 통한 전하운바자들의 안정적인 분리와 전극으로의 효율적인 수집이 필수적인다. 현재 양질의 다결정 실리콘 웨이퍼에 기반한 다결정 실리콘 태양전지 양산공정에서 16~17% 발전효율이 이루어지고 있으며 18% 이상의 발전효율을 얻기 위해서는 보다 더 우수한 품질의 다결정 실리콘 웨이퍼가 요구된다. 본 연구에서는 15.5~16.5% 대역의 평균 발전효율을 갖는 15.6 cm${\times}$15.6 cm 크기 고효율 다결정 실리콘 태양전지 전면의 전자발광(EL : electroluminescence)데이터로부터 효율기여도가 높은 위치와 상대적으로 기여도가 낮은 위치들을 선정하여 380~1050nm 파장대역의 광선속에 대해 국부적인 외부양자효율(EQE : external quantum efficiency)을 측정하고 투과전자현미경(TEM : tunneling electron microscope) 등을 활용하여 결정방향 등에 기인하는 양자효율 악화기구를 분석하였다. 결론적으로 15%대의 상대적으로 낮은 발전효율을 보이는 태양전지들은 300~600 nm 단파장 영역에서 양자효율이 상대적으로 낮은 저급한 결정성의 웨이퍼에 기인하고 16.5%이상의 높은 발전효율을 갖는 태양전지들은 단파장영역에서 높은 양자효율을 갖는 영역이 수광면적의 80~90%를 차지하는 것으로 밝혀졌다. 이와 더불어 15%대의 발전효율을 갖는 태양전지에서는 600~1100 nm 파장대역에서 상대적으로 악화된 양자효율을 갖는 저급한 결정성 영역이 30~40%를 차지하였으나 16.5%대역의 고효율 태양전지에서는 저급한 결정성 영역이 5~10%를 차지하여 대조를 보였다. 따라서 18%이상의 높은 발전효율을 갖는 다결정 실리콘 태양전지의 양산을 위해서는 양자효율이 우수한 양품의 웨이퍼를 기반으로 표면 texturing을 통해 평균 태양광 흡수율을 90%이상으로 개선하고, 보다 미세한 프론트 전극패턴을 통해 수광면적을 개선하고 선택적인 에미티공정 기술 등을 적용할 필요가 있음을 제안하고자 한다.

• Journal of Internet of Things and Convergence
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• v.9 no.1
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• pp.9-17
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• 2023

Deep learning with large amount of computations is difficult to implement on micro-sized IoT devices or moblie devices. Recently, lightweight deep learning technologies have been introduced to make sure that deep learning can be implemented even on small devices by reducing the amount of computation of the model. Quantization is one of lightweight techniques that can be efficiently used to reduce the memory and size of the model by expressing parameter values with continuous distribution as discrete values of fixed bits. However, the accuracy of the model is reduced due to discrete value representation in quantization. In this paper, we introduce various quantization techniques to correct the accuracy. We selected APoT and EWGS from existing quantization techniques, and comparatively analyzed the results through experimentations The selected techniques were trained and tested with CIFAR-10 or CIFAR-100 datasets in the ResNet model. We found out problems with them through experimental results analysis and presented directions for future research.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.850-856
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• 2011

The error diffusion method is one of the digital halftoning methods that diffuses quantization errors of current processing pixel to neighboring pixels and get a high-quality black-white image. This method has the problematic case which partially increase or decrease summation of diffused errors in the process of diffusing the quantization error. In this paper, we analyze Floyd-Steinberg method, Jarvis-Judice-Ninke method, Stucki method, and Shiau-Fan method as a representative case of error diffusion methods and propose a solution method of this problem.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.130-130
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• 2011

vertical light-emitting diodes의 표면을 건식과 습식 두 가지 공정을 통해 식각하여 roughening을 주었고, 또한 이 고정으로 인해 표면이 전체적으로 거칠기를 가지므로써 외부 양자 효율의 증가를 기대하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.3
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• pp.45-50
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• 2007

We present a auto compensating quantum key distribution system based on optical fiber at 1550nm. In the quantum key transmission system, main control board and phase modulation driving board are fabricated for auto controlling quantum key distribution(QKD). We tested the single photon counts per dark counts for a single photon detector, quantum key distribution rate($R_{sift}$) and the quantum bit error rate (QBER). Quantum bit error rate of 3.5% in 25km QKD is obtained. This system is commercially available.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.127-136
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• 1998

This paper proposes a new MVQMultistage Vector Quantizer) using a hybrid structure. While in a conventional MVQ, the quantizers of all stages perform the encoding procedure for input signals, we introduce a quantizer that performs selectively. The proposed quantizer with a hybrid structure is composed of a FSVQ(Finite-State Vector Quantizer) for the first stage and a ordinary VQ(Vector Quantizer) for the second stage. A input block is firstly encoded by the FSVQ of the first stage. If the Euclidean distortion measure between original signals and the codevector selected from the state codebook of the FSVQ is less than a prespecified value, only the FSVQ is used for image coding. Otherwise, both the FSVQ of the first stage and the ordinary VQ of the second stage are used for image coding. While the conventional MVQ has an advantage that can achieve low encoding complexity in comparison to the ordinary VQ, but has a disadvantage that is suboptimal with respect to the performance measure and can not achieve the bit rate reduction, the proposed method achieve not only the bit rate reduction but also the performance improvement.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.47-54
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• 2005

In the most of speaker recognition system, speaker's characteristics is extracted from acoustic parameter by speech analysis and we make speaker's reference pattern. Parameters used in speaker recognition system are desirable expressing speaker's characteristics fully and being a few difference whenever it is spoken. Therefore we su99est following to solve this problem. This paper is proposed to use strong spectrum characteristic in non-noise circumstance and prosodic information in noise circumstance. In a stage of making code book, we make the number of data we need to combine spectrum characteristic and Prosodic information. We decide acceptance or rejection comparing test pattern and each model distance. As a result, we obtained more improved recognition rate than we use spectrum and prosodic information especially we obtained stational recognition rate in noise circumstance.