• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.87.1-87
• /
• 2001

For a plant subject to several kinds of disturbances in the plant input side, we consider a problem of designing a controller based on the disturbance cancellation. The conventional loop transfer recovery (LTR) technique can not be used since the extended system consisting of the plant and the disturbance model is not necessarily stabilizable. We propose a new LTR technique that can be applied for our problem. As a target of the LTR, we choose a state feedback controller using a disturbance estimator. We find an LTR procedure based on the Riccati equation formalism where the stochastic model contains the filter gain matrix of the disturbance estimator in the target. The procedure recovers the target feedback ...

• Molecules and Cells
• /
• 제27권1호
• /
• pp.119-123
• /
• 2009

Porcine endogenous retroviruses (PERVs) gamma1 in the pig genome have the potential to act as harmful factors in xenotransplantation (pig-to-human). Long terminal repeats (LTRs) are known to be strong promoter elements that could control the transcription activity of PERV elements and the adjacent functional genes. To investigate the transcribed PERV gamma1 LTR elements in pig tissues, bioinformatic and experimental approaches were conducted. Using RT-PCR amplification and sequencing approaches, 69 different transcribed LTR elements were identified. And 69 LTR elements could be divided into six groups (15 subgroups) by internal variation including tandem repeated sequences, insertion and deletion (INDEL). Remarkably, all internal variations were indentified in U3 region of LTR elements. Taken together, the identification and characterization of various PERV LTR transcripts allow us to extend our knowledge of PERV and its transcriptional study.

• Journal of Microbiology and Biotechnology
• /
• 제18권6호
• /
• pp.1044-1049
• /
• 2008

In order to study functional nucleotides in prototype foamy virus (PFV) DNA on specific recognition by PFV integrase (IN), we designed chimeric U5 long terminal repeat (LTR) DNA substrates by exchanging comparative sequences between human immunodeficiency virus type-1 (HIV-1) and PFV U5 LTRs, and investigated the 3'-end processing reactivity using HIV-1 and PFV INs, respectively. HIV-1 IN recognized the nucleotides present in the fifth and sixth positions at the 3'-end of the substrates more specifically than any other nucleotides in the viral DNA. However, PFV IN recognized the eighth and ninth nucleotides as distinctively as the fifth and sixth nucleotides in the reactions. In addition, none of the nucleotides present in the twelfth, sixteenth, seventeenth, eighteenth, nineteenth, and twentieth positions were not differentially recognized by HIV-1 and PFV INs, respectively. Therefore, our results suggest that the functional nucleotides that are specifically recognized by its own IN in the PFV U5 LTR are different from those in the HIV-1 U5 LTR in aspects of the positions and nucleotide sequences. Furthermore, it is proposed that the functional nucleotides related to the specific recognition by retroviral INs are present inside ten nucleotides from the 3'-end of the U5 LTR.

• BMB Reports
• /
• 제51권2호
• /
• pp.55-56
• /
• 2018

Long terminal repeat retrotransposons (LTR-Rs) are major elements creating new genome structure for expansion of plant genomes. However, in addition to the genome expansion, the role of LTR-Rs has been unexplored. In this study, we constructed new reference genome sequences of two pepper species (Capsicum baccatum and C. chinense), and updated the reference genome of C. annuum. We focused on the study for speciation of Capsicum spp. and its driving forces. We found that chromosomal translocation, unequal amplification of LTR-Rs, and recent gene duplications in the pepper genomes as major evolutionary forces for diversification of Capsicum spp. Specifically, our analyses revealed that the nucleotide-binding and leucine-rich-repeat proteins (NLRs) were massively created by LTR-R-driven retroduplication. These retoduplicated NLRs were abundant in higher plants, and most of them were lineage-specific. The retroduplication was a main process for creation of functional disease-resistance genes in Solanaceae plants. In addition, 4-10% of whole genes including highly amplified families such as MADS-box and cytochrome P450 emerged by the retroduplication in the plants. Our study provides new insight into creation of disease-resistance genes and high-copy number gene families by retroduplication in plants.

• International Journal of Precision Engineering and Manufacturing
• /
• 제1권2호
• /
• pp.24-34
• /
• 2000

In this paper we propose a controller design method, called Quasi-LQG/$H_{\infty}$/LTR for nonlinear servo systems with hard nonlinearities such as Coulomb friction, dead-zone. Introducing the RIDF method to model Coulomb friction and dead-zone, the statistically linearized system is built. Then, we consider $H_{\infty}$ performance constraint for the optimization of statistically linearized systems, by replacing a covariance Lyapunov equation into a modified Riccati equation of which solution leads to an upper bound of the LQG performance. As a result, the nonlinear correction term is included in coupled Riccati equation, which is generally very difficult to thave a numerical solution. To solve this problem, we use the modified loop shaping technique and show some analytic proofs on LTR condition. Finally, the Quasi-LQG/$H_{\infty}$/LTR controller for a nonlinear system is synthesized by inverse random input describing function techniques (ITIDF). It is shown that the proposed design method has a better performance robustness to the hard nonlinearity than LQG/$H_{\infty}$/LTR method via simulations and experiments for the timing-belt driving servo system that contains the Coulomb friction and dead-zone.

• Asian-Australasian Journal of Animal Sciences
• /
• 제21권11호
• /
• pp.1572-1575
• /
• 2008

The xenotransplantation of pig organs and cells can be related with a risk of transmission of infectious diseases to human. Previous findings indicate that the regulatory region of PERV for retroviral transcription, replication and integration into the cellular DNA is located on the 5' Long Terminal Repeat (LTR). The objective of this study is the investigation of methylation and deletion status of the PERV 5' LTR region which can be used for regulating PERV expression. We compared the sequences of genomic DNA and bisulfite-treated genomic DNA from PK-15 cells expressing PERV to observe the methylation status of the 5' LTR. Our results showed that the CpG sites of U3 were methylated and methylation was inconsistent in the R and U5 regions. Also, variable numbers of 18 bp repeats and 21 bp repeats were detected on 5' LTR by sequencing analysis. The consistent U3 methylation might be indicative of host suppression of expression of the retroviruses.

• 한국균학회지
• /
• 제29권1호
• /
• pp.41-46
• /
• 2001

SD계 랫트를 사용하여 6주 동안 탄수화물 대용으로 50% 및 100%의 Lentinus tuber-regium(LTR)-첨가 투여그룹의 산화적 스트레스 및 방어체계에 미치는 영향을 평가하였다. LTR-50 및 LTR-100 투여그룹은 대조그룹 대비 21.7% 및 16.4%의 매우 유의적인 ${\cdot}OH$ 라디칼의 생성 억제효과가 인정되었고, 이들 두 투여그룹은 대조그룹 대비 약 10%의 $H_2O_2$의 생성 억제효과 및 $6{\sim}10%$ 정도의 바람직한 NO의 생성 억제효과가 인정되었다. 그렇지만 이들 LTR 투여에 의하여 ${O_2}^-$ 라디칼의 생성 억제효과는 인정할 수 없었다. 이들 활성산소의 공격에 의한 산화적 스트레스로서 LPO의 생성은 LTR 투여에 의하여 대조그룹 대비 $6{\sim}12%$의 유의적인 LPO의 생성 억제효과가 인정되었고, OP의 생성은 이들 LTR의 부여에 의하여 대조그룹 대비 5.0% 및 12.8%의 생성 억제효과가 인정되었다. 이들 LTR-50, LTR-100 투여그룹은 대조그룹에 비해 $15{\sim}50%$의 매우 유의적인 SOD의 활성 증가효과가 인정되었고, 또한 이들 LTR투여그룹의 GSHPx은 대조그룹 대비 $10{\sim}25%$의 매우 유의적인 GSHPx의 활성 증가효과가 인정되었다. 한편 CAT의 활성에 미치는 LTR투여의 영향도 대조그룹 대비 $60{\sim}90%$의 매우 유의적인 CAT의 활성 증가효과가 인정되었다. 이상의 결과에서 탄수화물 대용으로 사용된 유용버섯 LTR의 투여는 ${\cdot}OH$ 라디칼, $H_2O_2$ 및 NO의 생성 및 그로 인한 LPO 및 OP 같은 산화적 스트레스를 효과적으로 억제할 수 있을 뿐만 아니라 SOD, GSHPx 및 CAT 같은 방어효소의 활성을 매우 효과적으로 증가할 수 있기 때문에 노화를 매우 효과적으로 억제할 수 있을 것으로 기대된다.

• 대한기관식도과학회지
• /
• 제13권2호
• /
• pp.50-56
• /
• 2007

Background and Objectives: Laryngotracheal stenosis and its reconstruction in children is a highly challenging field to airway surgeons, and the way of stenting after a reconstructive surgery is still controversial. The aims of this study were to analyze the single institutional experiences of laryngotracheal reconstruction (LTR) in the pediatric patients with laryngotracheal stenosis and to compare the outcomes of single-stage LTR (SSLTR) with conventional two-stage LTR (TSLTR) in these patients. Materials and Methods: Medical records of 14 children (mean age 4.1 years) were reviewed, who received 20 LTR including 6 revisions for their moderate to severe subglottic stenosis and/or combined posterior glottic stenosis. Of these 20 LTR, tracheostoma was temporarily maintained after LTR in 12 cases (TSLTR) or not in the other 8 cases (SSLTR). Results: Overall decannulation rate of LTR that were performed before and after the year of 2003 was 40% (4/10) and 70% (7/10) respectively. Decannulation rate was 42% (5/12) in TSLTR group and 75% (6/8) in SSLTR group (P = 0.197). Mean interval to decannulation after LTR was 9.8 months and 7.2 days in TSLTR and SSLTR groups respectively (P = 0.004). A number of additional touch-up procedures that were required after LTR was 4 in TSLTR and 2.7 in SSLTR group (P = 0.238). Major complication rate was similar in both groups (33% in TSLTR and 38% in SSLTR, P = 0.910). Conclusion: A laryngotracheal reconstruction in children is a technically demanding procedure and its outcome is largely dependent on the surgeon's experience. Albeit there was a tendency that SSLTR ofters a higher decannulation rate, less additional touch-up procedures and similar complication rates, a shorter interval to decannulation after LTR was the only advantage that was confirmed as statistically significant in this study.

• 한국균학회지
• /
• 제42권1호
• /
• pp.50-56
• /
• 2014

본 연구에서는 큰느타리버섯 유전체내에 있는 retrotransposon의 탐색을 위하여 degenerated primer를 이용하여, retrotransposon library를 대장균에 제작하였다. 제작된 library에서 총 256개의 콜로니를 선택하여 염기서열을 결정한 결과, 71개가 LTR retrotransposon이며, 이들 중 70개가 Gypsy-type LTR retrotransposon임을 염기서열분석을 통하여 확인하였다. 특히 송이에서 발견된 MarY1_TM과 진황녹슨버짐버섯의 Gypsy-8_SLL이 각각 14, 18 copy 이상 큰느타리버섯 유전체에 삽입되어 있음을 Southern blot 분석을 통하여 밝혔다. 이와 더불어, 이들이 full length retrotransposon mRNA을 생산하고 있음을 RT-PCR과 northern blot을 통하여 밝힘으로서 활성이 있는 LTR retrotransposon임을 증명하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
• /
• pp.324-327
• /
• 1996

This paper describes the robust controller design methods applied to the problem of an automatic system for tow-vehicle/trailer combinations. This study followed an inverse Linear Quadratic Regulator(LQR) approach which combines pole assignment methods with conventional LOR methods. It overcomes two concerns associated with these separate methods. It overcomes the robustness problems associated with pole placement methods and trial and error required in the application of the LQR problem. Moreover, a Kalman filter is used as the observer, but is modified by using the loop transfer recovery (LTR) technique with modified transmission zero assignment. The proposed inverse LQG,/LTR controllers enhances the forward motion stability and maneuverability of the combination vehicles. At high speeds, where the inherent yaw damping of the vehicle system decreases, the controller operates to maintain an adequate level of yaw damping. At backward moton, both 4WS (2WS tow-vehicle, 2WS trailer) and 6WS (4WS tow-vehicle, 2WS trailer) control laws are proposed by using inverse LQG/LTR method. To evaluate the stability and robustness of the proposed controllers, simulations for both forward and backward motion were conducted using a detailed nonlinear model. The proposed controllers are significantly more robust than the previous controllers and continues to operate effectively in spite of parameter perturbations that would cause previous controllers to enters limit cycles or to loose stability.