A Study on adult learners experience of non-persistence in distance education

학위논문(박사) --서울대학교 대학원 :교육학과,2008. 8.Docto

성인의 미디어문해 학습과정에 관한 연구

학위논문(석사)--서울대학교 대학원 :교육학과 평생교육전공,1997.Maste

Preclinical evaluation of duodenal mucosal regeneration for non-pharmacological intervention of type 2 diabetes mellitus

Introduction: Type 2 Diabetes Mellitus (T2DM) have become a major global health concern due to growing adoption of western dietary habits and an increasing aging population. Despite the growing demand for effective treatments, Type 2 diabetes remission using pharmacological methods alone remains challenging. The duodenum has been presented as a key organ for treatment of metabolic disorders including T2DM and obesity. Therefore, it is imperative that innovative non-pharmacological treatments related to the duodenum continue to be developed. Duodenal mucosal regeneration (DMR), which targets thickened mucosa to ablate and regenerate healthy tissue, has recently been implemented. However, current DMR procedures are complex and pose risks of irreversible damage, highlighting the need for developing safer and more effective methods. The aim of this study is to evaluate the therapeutic effects of advanced DMR application using T2DM animal model including rodent and pig. We also assess the efficacy of DMR using application with light emitting diodes (LED)/Organic light emitting diode (OLED) by quantitatively analyzing molecular biological results and gut microbiome changes between the treatment and control groups. Methods & Materials: In this preclinical trial, we utilized Goto-Kakizaki (GK) rat models of T2DM to conduct DMR using endoscopic application with LED/OLED. The study evaluated the safety and efficacy of an endoscopic application equipped with a dual-wavelength (630/850nm) point light source LED module and a catheter with a single-wavelength (650nm) surface light source OLED module. Additionally, scaled-up DMR application which is attachable to endoscopic to assess the potential for clinical application, the safety and efficacy of an expanded endoscopic attachment device with a dual-wavelength LED module were evaluated using T2DM mini pig model. Oral glucose tolerance tests (OGTT) were conducted in GK rats and diabetic mini pigs after fasting overnight to assess blood glucose levels at multiple intervals post-DMR. Biochemical and hormonal analyses were performed on plasma samples to measure liver enzyme activities and hormone concentrations, including insulin, glucagon-like peptide 1, and gastric inhibitory polypeptide. Histological examinations of the duodenum, liver, and pancreas included Hematoxylin and eosin, Masson trichrome, and multiplex immunohistochemistry staining, followed by digital analysis to evaluate tissue alterations and islet cell morphology. Additionally, microbiome analysis was performed on fecal samples to assess alterations in bacterial composition following DMR. Results: The promising therapeutic outcomes of DMR using LED and OLED catheters highlight the potential of these technologies in treating T2DM and related complications. Our research evaluated the efficacy of DMR with red or infrared LED light in a T2DM animal model, showing significant improvements in serum glucose levels, insulin sensitivity with preserved pancreatic islet and hepatic parameters in GK rats. Similarly, DMR with an OLED catheter resulted in notable reductions in blood glucose levels and improved insulin sensitivity, indicated by lower homeostasis model assessment-insulin resistance levels. Additionally, DMR with LED/OLED light significantly decreased liver fibrosis and altered the gut microbiome. These findings suggest that DMR using LED/OLED catheters directly impacts the duodenal mucosa, leading to consistent metabolic improvements and reduced liver fibrosis, further supporting its potential in enhancing metabolic outcomes. Conclusion: In conclusion, the endoscopic DMR using LED/OLED applications presents a noninvasive approach to improve glycemic control, reduce insulin resistance, preserve pancreatic islet regeneration, and modulate the gut microbiome. The findings not only suggest that DMR could serve as an effective treatment modality for metabolic disorders, including T2DM but also help validate the efficacy and safety of this DMR application. Further clinical trial using the endoscopic attachable DMR application based on dual wavelength are necessary to support the potential of this novel non-pharmacological treatment.Docto

Layered BP 알고리즘을 사용하여 천공된 LDPC 부호 복호의 수렴 속도 향상

학위논문(석사) - 한국정보통신대학교 : 공학부, 2007.2, [ viii, 51 p. ]Puncturing is well-known with rate-compatible punctured convolutional codes [1]. Ha et al. successfully show that it is also possible to design capacity-approaching rate-compatible punctured LDPC codes at very long block lengths [2, 3] and good practical rate-compatible punctured LDPC codes at short block lengths [4, 5]. Since [4, 5], some extensions to the work in [4, 5] have been devised to mitigate the performance losses at high code rates [6, 7, 8]. The extensions take structural advantages of specific types of LDPC codes. That is, the work in [6, 7] utilizes the dual-diagonal structure of repeat accumulate codes and quasi-cyclic LDPC codes, respectively. Although puncturing is a promising technique to realize rate-compatible LDPC codes, it has a few problems such as performance losses at high code rates and slow convergence of the belief-propagation (BP) decoding [9].The convergence speed is also an important issue in real applications since the slower convergence needs more iterations which result in more power consumption or longer decoding latency. However, to our best knowledge, there has not been any study on how to cope with the slow convergence problem with punctured LDPC codes.한국정보통신대학교 : 공학부

Comparative Analysis of Hyaluronidase-Mediated Degradation Among Seven Hyaluronic Acid Fillers in Hairless Mice

Purpose: Hyaluronic acid (HA) is the most common injectable dermal filler used for soft-tissue augmentation, and can be removed non-surgically by directly injecting hyaluronidase. In this study, the hyaluronidase-mediated degradation of different types of HA fillers implanted subcutaneously at the back of hairless mice having filler residence time of four days or three months were compared. Methods: Two sites at the back of female hairless mice were subcutaneously implanted with 0.1-mL of one of the seven HA fillers (NLL, NL, NDL, NVL, and ND, JUV(X+), and RESLYFT) and injected with 30 IU or 60 IU hyaluronidase per 0.1-mL filler after reaching a filler residence time of 4 or 91 days, respectively. Filler bolus projection was measured using three-dimensional optical imaging over a 72 h period, and the implantation sites were histologically examined 2 weeks after hyaluronidase injection. Results: Following hyaluronidase injection, all seven HA fillers showed a rapid decrease of filler volume within 24 h, and complete degradation was confirmed by histological examination after 2 weeks. There was no significant difference in filler volume reduction rate among the seven HA fillers, and no evidence of macroscopic or microscopic adverse effects were observed at the implantation sites. Conclusion: All seven HA fillers show comparable susceptibility to hyaluronidase-mediated degradation. HA fillers with prolonged filler residence time may require a higher dose of hyaluronidase to achieve efficient degradation owing to tissue integration