• Journal of Microbiology and Biotechnology
• /
• v.12 no.4
• /
• pp.622-627
• /
• 2002

Diphtheria toxin repressor (DtxR) binds to approximately 30 to 35-bp regions containing an interrupted 9-bp inverted repeat within a 19-bp core sequence. The core sequence is fairly conserved and critical for DtxR binding. The flanking regions that are consisted of 5 to 8 more of nucleotides from the core are also required for DtxR binding. The nucleotides in both flanking regions are A-T rich. To examine whether the A-T nucleotides in both flanking regions from the core have significant roles for DtxR binding, a DNA fragment was constructed based on the diphtheria tox promoter/operator, and DNA fragments with substitution of A and T nucleotides In the flanking regions to G and C were also constructed. To assess the effect of these substitutions on binding of DtxR and repressibility by DtxR, $\beta$-galactosidase activity from lacZ fused to the region was assessed. Gel mobility shift of the region by purified DtxR was also examined. The DNA fragments containing the mutations in the flanking regions still exhibited repression and mobility shift with DtxR. The core segment with the mutation is still, therefore, recognized by DtxR. Nonetheless, the results from the assays indicated that the substitution significantly decreased repression of the operator by DtxR in vivo under high-iron condition and decreased binding of DtxR to the operator. These results suggest that A and T nucleotides fur both flanking regions are preferred for the binding of DtxR.

• Journal of Broadcast Engineering
• /
• v.15 no.1
• /
• pp.29-39
• /
• 2010

This paper presents and analyzes laboratory test results of distributed translator (DTxR) for distributed frequency network (DFN) in the ATSC (Advanced Television Systems Committee) terrestrial digital TV broadcasting system. The DTxR laboratory test is classified to receiving part test and transmitting part test. The receiving part test includes dynamic range, random noise, single echo, and adjacent channel interference. The transmitting part test includes quality of output signal (out-of channel emission, quality of transmitting signal, and phase noise), frequency synchronization among output signals, and TxID (Transmitter Identification) signal's affect to the legacy receiver. By the laboratory test results, the receiving part of DTxR eliminates average -2.5 dB of single echo and has average 17.5 dB at TOV (Threshold of Visibility) under random noise environment. In addition, the transmitting part of DTxR satisfies the specification of US FCC (Federal Communications Commission), and frequency difference among DTxR output signals is less than 0.001 Hz.

• Journal of Broadcast Engineering
• /
• v.15 no.1
• /
• pp.40-51
• /
• 2010

This paper presents and analyzes field test results of distributed translator (DTxR) for distributed frequency network (DFN) in the ATSC (Advanced Television Systems Committee) terrestrial digital TV broadcasting system. In the field test, according to types of antennas and receivers in areas where are overlapped by two DTxRs' coverage, we measured reception power, noise margin reception possibility, and ease of reception at each test point. By the field test results, when two DTxRs are on, reception power and noise margin are increased than when one DTxR is on. However, reception rate and ease of reception are similar or increased according to types of receivers.

• Journal of Broadcast Engineering
• /
• v.15 no.1
• /
• pp.14-28
• /
• 2010

This paper considers technological requirements to broadcast digital television signals using distributed frequency network (DFN) in the advanced television systems committee (ATSC) transmission system and proposes distributed translator (DTxR) to meet such requirements. In the DFN, DTxR uses different frequency from main transmitter, but same among DTxRs. In addition, this paper introduces digital signal processing (DSP) techniques, which consist of demodulation, equalization, transmitter identification (TxID) generation and insertion, and modulation, to implement DTxR.

• Journal of Broadcast Engineering
• /
• v.14 no.4
• /
• pp.518-536
• /
• 2009

To verify the performance of a Distributed Translator Network(DTxR) system in the real world conditions, 5 legacy DTV broadcasting repeater sites were implemented with 5 DTxR systems and field-tested by the DTV field test truck. The 4 DTV broadcasting repeater sites are selected in congested areas where their service areas are overlapped and the 5th site is deviated from the other sites to examine the effect of long-delayed multipath signals. First of all, we checked the receiving signal of the main station that used as a transmitting signal in 5 DTxR systems on the pre-selected 60 test points and tested every case of a DTxR system's on & off except 1 repeater site due to the already built-in DTV repeater system. The test items are received signal electric field strength, noise margin, ease of reception and subjective evaluation of the picture quality for received signals. We used 3rd, 5th, and 6th generation DTV receivers to examine the differences of the receivability by each generation of DTV receivers. Reviewing the test results, we conclude that the DTxR system can be adopted in the current DTV Repeater sites and it could improve the quality and receivability of the main signals by extending the service areas and enhancing the signal levels in the shadow areas without using the extra broadcasting channels.

• Journal of Broadcast Engineering
• /
• v.13 no.4
• /
• pp.463-478
• /
• 2008

A Distributed Translator Network(DTxR) is a cost-effective and frequency-effective method which can use existing transmission utilities and can be constructed in a shorter time as compared with Multiple Frequency Network(MFN) or Single Frequency Network(SFN) using On Channel Repeater(OCR). In order to verify the feasibility of DTxR, this field test was done in 30 points of north-west area in Seoul using 3rd, 5th, and 6th generation DIV receivers. Electric field strength, noise margin and ease of reception were measured and subjective evaluation of video quality was done in these points during the field test. With the test result, an improvement of receiving quality was obtained and an ease of reception was increased in case of the 5th. and 6th. receiver. From the results, we conclude that DTxR is a feasible method in DIV networks.

• Horticultural Science & Technology
• /
• v.17 no.4
• /
• pp.473-475
• /
• 1999

This study was carried out to restore the fertility by suppression of male sterility-induced gene using an antisense construct. Tobacco (cv. Petit Havana SR1) was transformed with the binary vector containing a GBAN215-6 promoter, an antisense diphtheria toxin (DTx-A) gene (pKDA215b) and a hygromycin resistant gene. Seventy-six confirmed transgenic plants regenerated from leaf disks were designated as the $R_0$ generation and selfed to produce the $R_1$ generation. From the inheritance study, five $R_1$ lines with multiple copies of the antisense construct were selected and selfed to identify homozygosity for the antisense construct. In order to restore fertility and finally to select restore lines, five $R_2$ lines with multiple copies of the antisense construct were crossed with male sterile plants. From these crosses, three different phenotypes have been observed: completely restored, partially restored, and not restored pollens, and otherwise tobacco plants were phenotypically same as normal plants. These plants were scored for the degree of restoration and selected for further study.

• Horticultural Science & Technology
• /
• v.18 no.3
• /
• pp.342-347
• /
• 2000

The objectives of this study were to investigate the genetic and phenotypic features of male sterile transformants by pollen-specific expression of diphtheria toxin gene and to find out inheritance patterns of transgene to the next generation. When backcrossed (BC) progenies were tested for expression of kanamycin resistance ($Km^R$), 9 lines out of 13 lines, except 4 lines ($BC_{1}5-13,\;BC_{1}5-23,\;BC_{1}5-28,\;BC_{1}5-32$), showed the ratio of $Km^R$ to kanamycin sensitive ($Km^S$), from 1:30 to all $Km^S$. As a result, they were much lower than Mendelian segregation of a dominant gene. To determine whether male sterility is a heritable and stable trait, 5 male sterile plants ($BC_{1}5-13,\;BC_{1}5-14,\;BC_{1}5-23,\;BC_{1}5-32,\;BC_{1}5-33$ lines) which had different transgene copy numbers were backcrossed as female parents with pollens from wild type. To confirm the existence of the DTx-A gene in the genome of the progenies, PCR was conducted using specific primers of the DTx-A coding region. A PCR band of 428 bp was obtained from each generation, which is the predicted size of the DTx-A gene fragment. Trangenes were inherited to the next $BC_4T_0$ progenies and showed male sterility, however, based on the copy numbers of DTx-A gene male sterile plants did not show predicted ratio. When male sterile plants were backcrossed with fertile plants, fruit capsule sizes and seed settings were relatively reduced from those of selfing wild type plants. The fruit sizes and seed settings were reduced in proportion to the increase in the copy number of DTx-A gene.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.9-12
• /
• 2001

본 논문에서는 유럽 통신 표준화기구인 ETSI 의 SMGll에서 채택된 GSM Full Rate(FR) 보코더 알고리wma[1]을 Teak DSP Core를 이용하여 실시간 구현하였다. GSM FR 보코더는 유럽에서 사용하는 통신 시스템인 GSM 의 full-rate Traffic Channel(TCH)의 표준 코덱[2]으로서 GSM HR, GSM EFR GSM AMR과 더불어 모뎀칩 내에 장착되는 필수적인 음성 서비스이다. 구현된 GSM FR는 13.05kbps의 비트율을 가지고 있으며, 인코더와 디코더 기능 외에 voice activity detection(VAD)[3]블록과 DTX[4]블록 등의 부가 기능도 구현되어 있다. 구현에 사용된 Teak[5]는 DSP Group 의 16bit고정 소수점 DSP core로서 최대 140MIPS 의 성능을 낼 수 있고 400bits ALU 와 두개의 MAC 이 장착되어 있어 음성 및 채널 부호화기의 실시간 처리에 최적화 되어있다. 구현된 GSM FR 은 인코더와 디코더 부분이 각각 약 235 MIPS 및 1.19MIPS 의 복잡도를 나타내며, 사용된 메모리는 프로그램 ROM 3.9K words, 데이터 ROM(table) 396 words 및 RAM 932words이다.

• Journal of KIISE:Computer Systems and Theory
• /
• v.26 no.3
• /
• pp.371-379
• /
• 1999

본 연구에서는 기존의 IS-95B에서 IMT 2000으로의 자연스러운 진화를 지원하면서, IMT2000을 효과적으로 지원하기 위하여 CDMA 기반한 패켓데이타 서비스용 MAC 프로토콜을 설계하고 성능을 평가한다. 제안한 방안은 기본적으로 비연결형 패켓 전송 방식을 지원하여 채널의 재사용률을 높히고, 트래픽의 전송시에만 채널을 사용하는 DTX(Dis-continous Transmission Mode)에 기반하므로 채널 자원의 효율을 극대화 한다. 아울러 트래픽의 전송시 5ms에 기반한 전용제어 채널관리 기능을 제공하므로서 빠른 채널 제어를 지원한다. 또한 Sleep-mode에 기반한 전용 제어 채널 제어 기능을 제공하여 단말의 전력 감소를 최소화한다. 아울러, 상태 천이에 따라서 패켓의 송수신이 없는 경우에는 네트워크내의 데이터베이스 정보 관리 부하를 극소화 하는 방안을 제공한다. 특히, 본 논문에서 제안한 방안은 현재 cdmaOne 의 표준으로서 TR 45.5의 승인을 받아 ITU-R의 IMT2000 RTT(Radio Transmission Technology)로서 제출되어 있는 상태이다.