1D Lumped Method를 이용한 모형 부분 예혼합 가스터빈 연소기의 연소불안정 해석

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2017. 2. 윤영빈.Recently, fine dust generation in the East Asian region has been emerging as a serious problem in each spring. It is expected that the strategy of increasing the weight of the combined cycle power plant, which is an environmentally friendly type of power generation, will play a big role in reducing fine dust. Gas turbines that use various renewable fuel such as syngas, synthetic natural gas (SNG), and biogas are being steadily developed, as it is effective not only to reduce fine dust but also to reduce exhaust emissions. Also, partially premixed gas turbine combustor is basically designed as a lean burn and has the possibility of manifesting combustion instability phenomenon. Therefore, it is important to understand and predict combustion instability characteristics for various fuel compositions in gas turbine combustor development. The purpose of this study is to analyze the instability characteristic of partially premixed combustor according to combustor length, flame position and fuel composition using 1D lumped method. In addition, the prediction of the instability mode shifting, which is the unique phenomenon of partially premixed combustor, is conducted for the first time. As a study procedure, Flame Transfer Function (FTF) in various fuel compositions are obtained with photomultiplier tube (PMT) and hot wire anemometry (HWA). Then the length of the combustor and the position of the flame obtained through the OH-PLIF image were adjusted. In addition, the thermal properties for various fuel compositions were applied using the NASAs CEA code. The predictions of instability frequency of dominant longitudinal mode and multimode instabilities were similar to those of experimental results. As the length of the combustor increases, a decrease in the combustion instability frequency and a change in the instability mode are were predicted. Also, by analyzing the combustion instability characteristics according to the flame position, it is confirmed that the instability mode shifting phenomenon can be predicted only by the change of the flame position under the same FTF and fuel/air condition. In the overall fuel composition, the instability mode was predicted to increase as the percentages of H2 fuel composition increased, as in the combustion instability mode shifting phenomenon that occurred in the combustion experiments. Prediction of instability frequency and instability amplitude trends were improved by applying combustor temperature and reflection coefficient of experiment. Based on these results, it is possible to predict the instability amplitude tendency and suggest the direction to avoid instability during design and operation.CHAPTER 1 INTRODUCTION 1 1.1 Gas Turbine of the Combined Cycle Power Plant 1 1.2 Combustion Instability 3 1.3 Prediction of Combustion Instability 6 CHAPTER 2 APPRATUS AND EXPERIMENTAL METHOD 8 2.1 Flame Transfer Function Measurement System 8 2.2 1D Lumped Method with OSCILOS 11 2.2.1 Combustion Geometry 12 2.2.2 Flame Position 14 2.2.3 Thernal Properties 16 2.2.4 Flame Model 17 2.2.5 Boundary Condition 19 2.3 Test Conditions for Rrediction 20 CHAPTER 3 RESULTS AND DISCUSSION 22 3.1 Prediction of Instability with Combustor Length Variation 22 3.2 Prediction of Instability with Flame Position Variation 25 3.3 Prediction of Instability with Fuel Composition Variation 27 3.4 Prediction of Instability Mode Shifting Phenomenon 29 3.5 Prediction Accuracy Improvement 32 3.5.1 Application of Combustor Temperature 32 3.5.2 Application of Reflection Coefficient 35 CHAPTER 4 CONCLUSION 41 REFERENCES 42 ABSTRACT IN KOREAN 45Maste

Formation of Artificial Lipid Membrane and their Photolysis in Mineral Water including Germanium

We have attempted to determine the Germanium ion (Ge 4+ ) effect on the human body by observing the formation of artificial lipid membrane and photolysis in the mineral water containing Ge 4+ ion. The artificial lipid membrane is prepared by using the phospholipid in the Germanium water and the formation efficiency of the liposomes is compared with those obtained in the plain mineral water without Ge 4+ ion. This work shows that the liposomes are formed in the Germanium water better than in the non-Germanium water. The liposomes can be photolyzed by superoxide anion (O 2 -. ) produced in the presence of some peptide such as NAT (N-acethyl-L-tryptophan). However, this is inhibited by superoxide dismutase (SOD), and it was found that the activity of SOD on the inhibition of the liposomes oxidative damage is higher in the Germanium water than in the non-Germanium water. It is concluded that the Ge 4+ ion in mineral water helps the formation of new cell as well as elevation of SOD activity for the lipid oxidation

Parallelized Seeded Region Growing Using CUDA

This paper presents a novel method for parallelizing the seeded region growing (SRG) algorithm using Compute Unified Device Architecture (CUDA) technology, with intention to overcome the theoretical weakness of SRG algorithm of its computation time being directly proportional to the size of a segmented region. The segmentation performance of the proposed CUDA-based SRG is compared with SRG implementations on single-core CPUs, quad-core CPUs, and shader language programming, using synthetic datasets and 20 body CT scans. Based on the experimental results, the CUDA-based SRG outperforms the other three implementations, advocating that it can substantially assist the segmentation during massive CT screening tests

Porphyra tenera Extracts Have Immune Stimulation Activity via Increasing Cytokines in Mouse Primary Splenocytes and RAW264.7 Macrophages

Abstract Porphyra tenera has long been consumed as food in Korea and Asia. The effects of Porphyra tenera extracts on the immune system are largely unknown. Therefore, this study investigated the immune-stimulating effects of ethanol and water extracts of P. tenera. The immunomodulatory potential of P. tenera was evaluated by determining its effect on cell viability and cytokine expression of mouse RAW264.7 cells and splenocytes. We investigated the effect of 10% ethanol extracts of laver (P. tenera) on the RAW264.7 cells. Production of nitric oxide (NO) and cytokines (interleukin [IL]-1β, IL-2, and IL-4, inducible NO synthase, and interferon-γ) in RAW264.7 macrophages was slightly higher after treatment with P. tenera extracts. Ethanol extracts upregulated and enhanced the functions of macrophages, such as NO and cytokines (IL-1β, IL-2, and IL-4, inducible NO synthase, and interferon-γ) production. In addition, cytokine concentrations were significantly increased in cells treated with different doses of P. tenera ethanol extracts compared to the control group. Overall, the results demonstrated that P. tenera extracts enhanced cytokine secretion in mouse splenocytes and macrophages. From these findings, it can be concluded that P. tenera possess a natural compound with immune-stimulatory activity. P. tenera extract is a good immunostimulant from natural compounds

Simulation Method for the Physical Deformation of a Three-Dimensional Soft Body in Augmented Reality-Based External Ventricular Drainage

Objectives Intraoperative navigation reduces the risk of major complications and increases the likelihood of optimal surgical outcomes. This paper presents an augmented reality (AR)-based simulation technique for ventriculostomy that visualizes brain deformations caused by the movements of a surgical instrument in a three-dimensional brain model. This is achieved by utilizing a position-based dynamics (PBD) physical deformation method on a preoperative brain image. Methods An infrared camera-based AR surgical environment aligns the real-world space with a virtual space and tracks the surgical instruments. For a realistic representation and reduced simulation computation load, a hybrid geometric model is employed, which combines a high-resolution mesh model and a multiresolution tetrahedron model. Collision handling is executed when a collision between the brain and surgical instrument is detected. Constraints are used to preserve the properties of the soft body and ensure stable deformation. Results The experiment was conducted once in a phantom environment and once in an actual surgical environment. The tasks of inserting the surgical instrument into the ventricle using only the navigation information presented through the smart glasses and verifying the drainage of cerebrospinal fluid were evaluated. These tasks were successfully completed, as indicated by the drainage, and the deformation simulation speed averaged 18.78 fps. Conclusions This experiment confirmed that the AR-based method for external ventricular drain surgery was beneficial to clinicians

Alternative Splicing Regulation of Human Telomerase Reverse Transcriptase (TERT): Cancer Therapeutic Implications, Discovery of Novel TERT Isoforms, and Impact of Exercise and Aging

Aging is associated with an elevated cancer risk due to the cumulative genetic mutations, cellular damage, and loss of immune cell function. Telomeres, the protective caps at the ends of linear chromosomes, naturally shorten with age, making them a key biomarker of the aging process. Higher levels of physical activity and exercise compared to a sedentary lifestyle are consistently linked to enhanced telomere maintenance in immune cells. Longer telomeres in immune cells may lead to greater anti-tumor immunosurveillance which may underpin the reduced risk of cancers observed in more active individuals. Telomeres are maintained by telomerase, the enzyme that can synthesize telomere repeats. Telomerase is predominantly repressed in somatic cells and is re-activated by cancer cells to ensure their immortality. Conversely, overexpression of telomerase extends lifespan of animals and exercise is associated with higher levels of telomerase activity in immune cells and other tissues. Telomerase activity is regulated by the mRNA and protein expression of TERT, which is the rate-limiting component of telomerase. A key mechanism of TERT mRNA and protein expression regulation is alternative RNA splicing (AS). However, we do not currently know the transfactors that dictate splicing choice, the impact of exercise on thymus TERT AS, the full catalogue of TERT AS isoforms, or the function of most TERT AS isoforms. Understanding the regulation of TERT and telomerase has implications for both aging and cancer therapies, as upregulation of telomerase activity can slow down telomere shortening, potentially mitigating the aging process, while inhibiting telomerase can offer a strategy to impede cancer growth. Thus, the major objectives of my dissertation were to elucidate new transfactors important to cancer cell TERT AS regulation, examine how exercise impacts TERT AS regulation in the thymus, and determine the catalogue of TERT AS isoforms and their functions. The central premise was that TERT AS exhibits distinct regulation depending on the physiological context, and a more complete understanding of telomerase regulation will result in novel therapies for cancer and aging. We tested this central premise in four separate but related projects as part of my dissertation work. In the first study, we found that a splicing factor, SF3B4, regulated TERT AS in lung cancer cells, and when SF3B4 was reduced, it inhibited telomerase activity and cancer cell growth, indicating a potential novel cancer therapeutic target. In the second study, we identified lung cancer-specific TERT AS regulatory factors (U2AF2 and SRSF2). In the third study, we observed that aging reduced thymus TERT expression and three weeks of voluntary wheel running impacted the AS of TERT in transgenic mice expressing human TERT. In the fourth study, we discovered a novel TERT isoform, Delta 2-4, and determined that it does not function in telomere biology but rather protects lung cancer cells from apoptosis. Collectively, these studies advance our understanding of telomerase regulation, thereby offering potential implications for cancer and aging therapies, and also establishes a fundamental basis for future studies, ultimately leading towards a more complete understanding of telomerase regulation.PhDMovement Science PhDUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/192326/1/snujjk_1.pd