• Journal of Microbiology and Biotechnology
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• 제30권12호
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• pp.1919-1926
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• 2020

CRISPR interference (CRISPRi) has been developed as a transcriptional control tool by inactivating the DNA cleavage ability of Cas9 nucleases to produce dCas9 (deactivated Cas9), and leaving dCas9 the ability to specifically bind to the target DNA sequence. CRISPR/Cas9 technology has limitations in designing target-specific single-guide RNA (sgRNA) due to the dependence of protospacer adjacent motif (PAM) (5'-NGG) for binding target DNAs. Reportedly, Cas9-NG recognizing 5'-NG as the PAM sequence has been constructed by removing the dependence on the last base G of PAM through protein engineering of Cas9. In this study, a dCas9-NG protein was engineered by introducing two active site mutations in Cas9-NG, and its ability to regulate transcription was evaluated in the gal promoter in E. coli. Analysis of cell growth rate, D-galactose consumption rate, and gal transcripts confirmed that dCas9-NG can completely repress the promoter by recognizing DNA targets with PAM of 5'-NGG, NGA, NGC, NGT, and NAG. Our study showed possible PAM sequences for dCas9-NG and provided information on target-specific sgRNA design for regulation of both gene expression and cellular metabolism.

• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.603-610
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• 2008

In this paper, analytical methods for calculating the average probability of bit error of direct sequence pulse amplitude modulation ultra wideband (DS-PAM UWB) system and time hopping pulse position modulation ultra wideband (TH-PPM UWB) system are given. For the multi-user DS-PAM UWB system, the bipolar pulse amplitude modulation is used in order to achieve better performance. As we know, more attention is paid to the TH-PPM UWB systems recently. In this paper. we first introduce the accurate BER calculation methods of the multi-user DS-PAM UWB and TH-PPM UWB systems and then give the performance analysis over the ideal AWGN channel and a correlation receiver. Furthermore, we also introduce their applications in image transmission and data transmission and give the simulation results. The analytical method yields simple and exact formulas relating the performance to the system parameters.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.447-450
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• 2009

본 논문에서는 2PAM(binary pulse-antipodal modulation) DS(direct-sequence) UWB(ultra-wideband) 시스템을 V-BLAST(vertical bell lab layered space-time) 구조를 사용하는 MIMO(multiple input multiple output) 시스템에 적용하여 실내 무선 채널 환경에서 고속 데이터 전송률을 달성하고자 한다. 이러한 2PAM DS UWB MIMO 시스템의 BER 성능과 송수신 안테나의 차원과의 관계가 논의된다. 또한, UWB-MIMO 시스템의 수신기에서는 ZF(zero-forcing), ZF-OSIC(ordered successive interference cancellation), MMSE(minimum-mean-square-error), MMSE-OSIC, ML(maximum likelihood)과 같은 다양한 MIMO(multiple input multiple output)와 같은 다양한 MIMO 검출기법이 비교, 분석된다.

• Interdisciplinary Bio Central
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• 제6권4호
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• pp.3.1-3.10
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• 2014

Amino acid substitution matrices are essential tools for protein sequence analysis, homology sequence search in protein databases and multiple sequence alignment. The PAM matrix was the first widely used amino acid substitution matrix. The BLOSUM series then succeeded the PAM matrix. Most substitution matrixes were developed by using the statistical frequency of substitution between each amino acid at blocks representing groups of protein families or related proteins. However, substitution of amino acids is based on the similarity of physiochemical properties of each amino acid. In this study, a new approach was used to obtain major physiochemical properties in multiple sequence alignment. Frequency of amino acid substitution in multiple sequence alignment database and selected attributes of amino acids in physiochemical properties database were merged. This merged data showed the major physiochemical properties through principle components analysis. Using factor analysis, these four principle components were interpreted as flexibility of electronic movement, polarity, negative charge and structural flexibility. Applying these four components, BAPS was constructed and validated for accuracy. When comparing receiver operated characteristic ($ROC_{50}$) values, BAPS scored slightly lower than BLOSUM and PAM. However, when evaluating for accuracy by comparing results from multiple sequence alignment with the structural alignment results of two test data sets with known three-dimensional structure in the homologous structure alignment database, the result of the test for BAPS was comparatively equivalent or better than results for prior matrices including PAM, Gonnet, Identity and Genetic code matrix.

• 대한전자공학회논문지SD
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• 제46권11호
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• pp.84-91
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• 2009

본 논문은 multi-level signaling을 이용한 high speed serial link transmitter에 관하여 제안하였다. High speed serial link에서 수 Gb/s를 달성하기 위해 4-pulse amplitude modulation (PAM) 을 사용하였다. 4-PAM은 4개의 level로 한 symbol time에 2 bit data를 전송함으로써 binary signaling보다 2배 빠른 data 전송이 가능해졌다. 제안된 4-PAM transmitter는 전압 output 대신 전류 output을 생성하며 이로 인해 driver의 switching time이 빨라져서 더 높은 속도의 transmitter를 구현할 수 있었다. $2^5-1$ pseudo-random bit sequence (PRBS) 생성기는 built-in self test (BIST)를 하기 위해 on-chip으로 설계되었다. 본 연구는 동부 하이텍 $0.18{\mu}m$ CMOS 공정을 통하여 설계되었으며 1.8 V supply voltage에서 eye 크기가 160 mV 이고 최대 동작 속도는 8 Gb/s이다. 칩 전체 면적은 $0.7\times0.6mm^2$이며 전력 소모는 98 mW이다.

• 한국정보통신학회논문지
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• 제9권8호
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• pp.1656-1662
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• 2005

본 논문에서는 기존의 UWB 통신 시스템에서 많이 사용되는 펄스 위치 변조와 펄스 진폭 변조를 사용하여 하나의 펄스로서 여러 비트의 데이터를 전송할 수 있는 M-PPAM(M-ary Pulse Position and Amplitude Modulation) 구조를 소개하였다. 이 방법은 동일한 데이터 전송율을 얻기 위하여 보다 긴 펄스 반복 주기를 사용할 수 있는 장점이 있다. 따라서 실내 환경에서와 같은 다중 경로 페이딩이 심한 경우 대용량의 데이터를 전송하기에 적합하리라고 생각한다. 이때, 다중 사용자를 수용하기 위하여 DS(Direct Sequence) 기법을 사용하였다. 이와 같이 고려된 M-PPAM DS-UWB 수신기의 성능을 가우시안 채널 조건하에서 다중 사용자 간섭을 포함하여 표준 가우시안 근사(Standard Gaussian Approximation)를 사용하여 모델링 하였다. 또한, 수신기의 성능을 시뮬레이션을 통하여 확인하였다.

• 펄프종이기술
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• 제41권2호
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• pp.13-19
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• 2009

In order to produce high quality paper at the lowest cost in high speed, typically various polyelectrolytes as retention aids were used. Retention systems such as single polymer system, dual polymer system, and microparticle system were used. The objective of this study was to analyze the changes of retention, drainage, formation and fracture toughness depending on types of retention system, molecular weight of C-PAM and dosage sequences of agents. When single polymer system was applied, retention was increased with poor formation and drainage. When common microparticle system(C-PAM/bentonite) was used, high molecular weight PAM gave high retention and fast drainage, but poor formation. When the microparticle system with reverse dosage sequence(bentonite/C-PAM) was used, low molecular weight PAM gave high retention, fast drainage and good formation. When various retention agents were applied, fracture toughness was increased than that of blank. When using high molecular weight PAM and consequently causing excessive flocculation, fracture toughness was decreased.

• 한국인터넷방송통신학회논문지
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• 제9권2호
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• pp.117-122
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• 2009

본 논문에서는 다중 안테나 (Multiple-Antenna)를 적용한 초광대역 무선통신 (UWB: Ultra Wide-Band) 시스템에서 이중 이진 터보 부호의 성능을 보인다. 본 논문에서는 PPM-TH (Pulse Position Modulation-Time Hopping) 방식과 PAM-DS (Pulse Amplitude Modulation-Direct Sequence) 방식의 UWB 시스템을 모두 고려하였으며, 다중 안테나 기술로 시공간 블록 부호 (STBC : Space Time Block Code) 송신 다이버시티와 수신 다이버시티 기술을 적용하였다. 그리고 이진 터보 부호에 비해서 부호어 사이의 최소 거리 (Minimum Distance)가 길어서 복호 성능이 좋으며 처리량 (Throughput)이 높아서 복호 처리 시간이 짧은 장점을 가지고 있는 이진 이중 터보 부호를 적용하였다. 본 논문의 결과는 UWB 시스템을 구현하는데 적용될 수 있다.

• ETRI Journal
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• 제29권3호
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• pp.322-328
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• 2007

We propose a direct-sequence pulse-amplitude modulation (DS-PAM) ultra-wideband (UWB) system which employs a non-linear chirp waveform instead of the conventional Gaussian monocycle in this paper. In the approved frequency for UWB, there exist myriad narrowband interferers. Specifically, we focus on the mutual interference between UWB systems and 802.11a WLAN. This paper offers a method to suppress this in-band narrowband interference by introducing a kind of non-linear chirp waveform. Using the proposed non-linear chirp waveform, the effects of one or more narrowband interference sources with different frequencies can be suppressed. System performance of UWB systems in the narrowband interference environment can be improved. Computer simulations with additive white Gaussian noise successfully demonstrate an increase in performance with the proposed system as compared to traditional linear chirp systems.

• Bioinformatics and Biosystems
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• 제2권1호
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• pp.7-11
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• 2007

하나의 아미노산이 다른 아미노산으로 바뀌는 가능성을 계통학적인 나무를 이용해서 치환행렬로 만들었다. PFMT(Phylogenetic Focused Mutaion Tendency)행렬은 기존의 PAM160이나 BLOSUM62와 다르게 공통조상으로부터 상위 종으로 치환되는 가능성을 점수화 하였다. COGs의 데이터베이스에 있는 152KOGs를 뽑아서 아미노산의 치환횟수를 점수화하였다. PFMT 행렬은 어떤 서열보다 더 상위 종의 서열을 비교할 때 유용하게 쓰일 수 있으며 2개의 아미노산간의 치환 관계를 더 자세하게 볼 수 있게 한다.