탄소 고분자 경량 복합재료의 열 전달 거동에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 공과대학 재료공학부, 2017. 8. 윤재륜.To investigate thermal behavior of lightweight carbon/polymer composites and to explore the potential applications of composites are the main topics of this study. Present study dealt with unique experimental results such as synergistic improvement in thermal conductivity of multiphase composites and enhancement in surface hardness of graphene aerogel-based composites. To explore dominant factors determining the thermal conductivity of the carbon/polymer composites is also an important goal of this study. In Chapter 2, the thermal conductivity of composites with a polyphenylene sulfide (PPS) matrix and a mixture of boron nitride (BN) powder and multi-wall carbon nanotube (MWCNT) fillers was investigated. Synergistic improvement in thermal conductivity of the composite was obtained by introducing a combination of BN and MWCNT. The improvement of thermal conductivity was strongly depended on surface treatments of the MWCNTs, such as hydrogen peroxide and acid treatments. The thermal conductivity of the composite was affected by the interaction and interfacial thermal resistance between the PPS matrix and the BN filler. The interfacial thermal resistance of PPS/BN/MWCNT composites was investigated quantitatively by finite element method. The highest thermal conductivity was 1.74 W/m·K achieved by the composite with 1 wt% MWCNT that had been treated by hydrogen peroxide., This result indicated that we successfully fabricated a pelletizable, injection moldable, thermally conductive carbon/polymer composite, considering the specific thermal conductivity of the prepared composite. In Chapter 3, three-dimensional carbon nanomaterial reinforced composite aerogel was fabricated using a freeze-drying method. Graphene nanoplatelets (GNPs) were used as the reinforcement and poly vinyl alcohol (PVA) as the organic binding material to produce the composite aerogel. Two different methods were employed to control the internal structure of the aerogel: a variation of solvent composition and the formation of cross-linking. The internal structure of the aerogel was affected by the types and composition of the solvent. In addition, the subsequent cross-linking of the aerogel influenced the morphology and physical properties. This study is expected to provide a simple and efficient way to control the internal structure and resulting properties of the GNP aerogel. In Chapter 4, the thermal and electrical conductivity of composites with a graphene aerogel and an epoxy matrix were investigated. We fabricated a core-shell structured composites with the graphene aerogel core and the epoxy/graphene composite shell in order to enhance the poor surface hardness of graphene aerogel, resulting in increased resistance of graphene aerogel to the external forces. The thermal conductivity of the core-shell structured epoxy/rGO composites was 0.077 W/m·K which is similar to that of thermal insulating materials. On the other hand, the electrical conductivity of composite was found to exhibit 0.5 S/m which is almost 10 orders of magnitude higher than that of neat epoxy. This result indicated that carbon/polymer composites have a great potential in numerous engineering applications.Chapter 1. Introduction 1 1.1. Carbon Nanomaterials 1 1.2. Factors Affecting Thermal Conducitivy 4 1.3. Applications of Carbon/Polymer Composite 7 1.4. Objetives 8 1.5. References 10 Chapter 2. Synergistic Improvement of Thermal Conductivity of Thermoplastic Composites with Mixed Boron nitride and MWCNT Fillers 14 2.1. Introduction 14 2.2. Experimetnal 17 2.2.1. Materials 17 2.2.2. Chemical Modification of MWCNT 17 2.2.3. Surface Characterization of MWCNT 19 2.2.4. Preparation and Characterization of Composites 19 2.3. Numerical Analysis 24 2.3.1. Representative Volume Element 24 2.3.2. Analytical Models 26 2.3.3. Computation Details 28 2.4. Results & Discussion 30 2.4.1. Moldabilty of Composites 30 2.4.2. Thermal Conducitivy of Composites 30 2.4.3. Morphology 32 2.4.4. Defect and Functionality of MWCNT 35 2.4.5. Numerical Results 43 2.5. Summary 52 2.6. References 53 Chapter 3. Morphology and Physical Properties of Graphene Nanoplatelet Embedded Poly(Vinly Alcohol) Aerogel 57 3.1. Introduction 57 3.2. Experimetnal 59 3.2.1. Preparation of GNP/PVA Aerogel 59 3.2.2. Characterization 59 3.3. Resutls & Discussion 62 3.3.1. Dispersion of GNP in Suspensions 62 3.3.2. Microstructure of Aerogel 64 3.3.3. Thermal Conductivity 71 3.3.4. Mechanical Property 71 3.3.5. Stability in Aqueous Environment 72 3.4. Application of GNP Embedded PVA Aerogel 77 3.4.1. Shape-Stability 77 3.4.2. DSC Thermal Spectra 77 3.4.3. Thermoelectric Effectivity 78 3.5. Summary 85 3.6. References 86 Chapter 4. Fabrication of Lightweight and Mechanically Enhanced Core-Shell Structured Epoxy/rGO Aerogel Composite 90 4.1. Introduction 90 4.2. Experimetnal 92 4.2.1. Materials 92 4.2.2. Synthesis of Graphene Oxide (GO) 92 4.2.3. Preparation 92 4.2.4. Characterization 95 4.3. Results & Discussion 96 4.3.1. Morphology 96 4.3.2. Thermal Conductivity of Epoxy/rGO and rGO Aerogel 99 4.3.3. Thermal Conductivity of Core-Shell Composite 99 4.3.4. Hardness of Core-Shell Structured Composite 106 4.3.5. Electrical Conductivity 106 4.4. Summary 110 4.5. References 111 Chapter 5. Concluding Remarks 114 Korean Abstract 117Docto

면역조직화학염색을 이용한 MET조절장애 폐선암 환자의 선별

학위논문 (석사)-- 서울대학교 대학원 : 임상의과학과 전공, 2016. 2. 김동완.Introduction: The proper target of a MET inhibitor has not been demonstrated in lung cancer. MET amplification, protein expression, and splice mutations at exon 14 are known to cause dysregulation of the MET/HGF pathway. Our study aimed to establish the strategy for finding target population of MET inhibitor by confirming the relationship among MET amplification, protein expression, and mutations in pulmonary adenocarcinoma. Methods: MET protein expression by immunohistochemistry (IHC) and MET amplification by fluorescence in situ hybridization (FISH) were evaluated in 316 surgically resected lung adenocarcinomas. The IHC score was defined by the modified criteria used in the clinical trial for the MET inhibitor, and the score of 2 or 3 was defined as positivity. MET gene copy number (GCN) and amplification was defined by University of Coloradeo Cancer Center criteria. Patients were divided into 4 groups (IHC-negative/FISH-negative, IHC-negative/FISH-positive, IHC-positive/FISH-negative, and IHC-positive/FISH-positive), and 15–20 tumors in each group were randomly selected for mutation analyses to find splice mutations at exon 14. Results: An IHC score of 0, 1, 2, and 3 was found in 168 (53.2%), 71 (22.5%), 59 (18.7%), and 18 (5.7%) tumors, respectively. The mean GCN was 3.56 (standard deviation 1.5)MET FISH positivity was detected in 123 (38.9%) samples, and 26 (8.2%) of them were gene amplifications. MET amplification were significantly associated with the IHC score (P<0.001, χ2 test), and the positive predictive value of the IHC score of 3 for predicting amplification was 44.4%. Splice mutations were identified in only 2 (2.9%) of 70 cases. One had a MET IHC score of 2 and negative FISH without amplificationThe other had a MET IHC score of 0 and positive FISH without amplification. MET IHC or FISH results were not prognostic indicators of overall survival in multivariate analysis. Conclusions: There is a significant relationship between MET amplification and protein expression, and selection of tumors with amplification using IHC was effective. However, because of its rarity, a selection strategy for mutated tumors is implausible using IHC or FISH.1.Introduction 1 2.Material and methods 4 2.1 Patient selection 4 2.2 Immunohistochemistry and fluorescence in Situ hybridization 4 2.3 Reverse transcription polymerase chain reaction and direct sequencing 5 2.4 Statistical analysis 6 3.Results 7 3.1 Clinicopathological features 7 3.2 IHC and FISH 9 3.3 Relationship between IHC and FISH 11 3.4 Mutation analysis 13 3.5 Survival analysis 16 4.Discussion 18 5.References 22 6.Abstract in Korean 28Maste

Comparison of Open and Robotic Surgery in Radical Prostatectomy: A Single Surgeon's Experience.

PURPOSE: To compare the results of open radical prostatectomy(OP) and robotic prostatectomy(RP) for a single surgeon's experience of 219 radical prostatectomy cases. MATERIALS AND METHODS: Between June 2002 and June 2007, 133 patients underwent OP and between July 2005 and June 2007, 86 patients underwent RP. To compare the surgeon's experience-related differences, we divided the OP cases into 73 early cases(OP-I) and 60 late cases(OP-II), and the RP cases into 30 early cases(RP-I) and 56 late cases(RP-II). The clinical characteristics, perioperative results, and early clinical outcomes were evaluated. RESULTS: There were no significant differences in the preoperative characteristics between the four groups. For the RP cases, the mean estimated blood loss was decreased, a normal diet was started earlier, the mean duration of hospital stay and the mean duration of bladder catheterization was shorter than for the OP cases. The frequency of intraoperative complications significantly decreased in the RP-II group as compared to the RP-I group. Although there was no significant statistical difference in the positive surgical margin rates between the four groups, the rates were slightly decreased in the RP-II group. The recovery period of continence was shorter in the RP-II group than in the OP group and for patients 60 years or older, recovery of potency was also better in the RP-II group than the OP group. CONCLUSIONS:Our results suggest that RP at the hands of an experienced surgeon may decrease the positive surgical margin rate to some degree. Additionally, performance of RP may lead to a shorter duration of bladder catheterization and hospital stay and a better recovery of continence and potency than obtainable by OP.ope

Robot-assisted Laparoscopic Radical Cystectomy with Ileal Conduit Urinary Diversion

PURPOSE: In this study, we detail our initial experience with robot-assisted laparoscopic radical cystectomy(RLRC) with ileal conduit urinary diversion(ICUD) and describe the stepwise surgical procedure. MATERIALS AND METHODS: Four men underwent RLRC with extracorporeal ICUD for muscle invasive bladder cancer. RLRC was performed by a single surgeon using the da Vinci(TM) robot system(Intuitive Surgical, Sunnyvale, USA) with four robot arms. The surgical specimen was extracted through the sub-umbilical incision, and ICUD was also achieved through the sub-umbilical incision by extracorporeal technique. RESULTS: The mean operative time was 355+/-49.8 minutes, and the mean estimated blood loss was 550+/-57.7ml. The mean hospital stay was 12+/-2.9 days. There were no major complications. On surgical pathology, one patient had pTis, one patient had pT1, and two patients had pT3 transitional cell carcinoma of the bladder. There were no positive surgical margins or lymph nodes. The mean number of dissected lymph nodes was 17+/-4.6(range: 12-23). CONCLUSIONS: Despite limited experience, RLRC is a feasible procedure with minimal blood loss, shorter hospital stay, and may be an alternative to the open techniqueope

Outcomes of Robotic Prostatectomy for Treating Clinically Advanced Prostate Cancer

PURPOSE: Robotic prostatectomy(RP) has been widely performed for treating clinically localized prostate cancer(PC), whereas for treating clinically advanced PC, prostatectomy is usually done by open methods. We evaluated the outcomes of RP for treating patients with clinically advanced PC as compared with the outcomes of RP for treating patients with clinically localized PC. MATERIALS AND METHODS: We performed RP in 273 patients with the da Vinci(R) robot system through a transperitoneal approach. Ninety-two patients had clinically advanced PC(Group I) and 181 patients had clinically localized PC(Group II). We compared the perioperative variables and early surgical outcomes between the two groups. RESULTS: The two groups did not show significant differences for their mean age, but the mean preoperative prostate-specific antigen(PSA) levels and biopsy Gleason scores were significantly higher in Group I. There were no significant differences in the mean operation time(Group I: 214.9+/-45.1 min, II: 217.8+/-49.0 min, p=0.709), the estimated blood loss(Group I: 382.8+/-281.5ml, II: 387.5+/-369.5ml, p=0.934), the duration of bladder catheterization (Group I: 12.0+/-2.8 days, II: 12.9+/-4.6 days, p=0.232), the hospital stay(Group I: 5.9+/-3.5 days, II: 5.0+/-2.4 days, p=0.154), and the time to start the postoperative regular diet(Group I: 2.5+/-1.5 days, II: 2.0+/-0.6 days, p=0.089) between the two groups. There was a significant difference in lymph node invasion(p<0.001), but no difference in the positive surgical margin(p= 0.180). Two out of the 4 intraoperative rectal injuries occurred in the clinically advanced PC group, but they were closed primarily without specific problems, except for 1 case. CONCLUSIONS: Our results suggest that RP may be performed safely for patients with clinically advanced PCope

Robot-assisted Laparoscopic Nephroureterectomy with a Bladder Cuff Excision

We report here on our technique and outcomes of the first two cases of robot-assisted laparoscopic nephroureterectomy with a bladder cuff excision(RLNU). RLNU was performed on two female patients who both had a muscle invasive lower ureter tumor. For the first step, nephroureterectomy was performed in the lateral flank position. For the second step, bladder cuff excision and bladder repair were performed in a steep Trendelenburg position. The specimen was extracted through a 6 cm sized incision in the umbilical trocar site. Both procedures were successfully completed with using the robot without conversion to open surgery. The total operative time, including the lymphadenectomy and the robot docking times, was 320 and 241 minutes, respectively, for the 2 patients. The estimated blood loss was 40 and 200 ml, respectively. The pathological examinations showed stage T3 and T2 invasive transitional cell carcinoma of the ureter. The patients' postoperative recoveries were uneventful and the bladder cuff was free of tumor. RLNU may have potential advantages over open and laparosopic surgery due to its minimal invasiveness. This approach can be an alternative to open surgery or laparoscopic techniqueope

Robot-assisted Laparoscopic Radical Prostatectomy: Clinical Experience of 200 Cases

PURPOSE: We report the initial functional and surgical results of 200 robot-assisted laparoscopic radical prostatectomies performed at our hospital, and evaluate the efficacy and safety of this surgery. MATERIALS AND METHODS: Between July 2005 and July 2007, 200 patients underwent robot-assisted laparoscopic radical prostatectomy(RLRP). All cases were performed using the four-arm da Vinci(TM) robot system (Intuitive Surgical, Mountain View, CA USA). RLRP was performed by two surgeons. All operations were approached transperitoneally. We studied the perioperative parameters and early surgical outcome retrospectively. RESULTS: The mean age at surgery was 64+/-8.2 years. The median preoperative prostate-specific antigen level was 8.24 ng/ml(range, 1.37-726.60 ng/ml) and the mean preoperative Gleason score was 6.5(range, 4-9). The median total operative time was 215 min(range, 140-418 min) and the median estimated blood loss was 300ml(range, 50-2,700ml). A positive surgical margin was found in 64 patients(32.0%). A normal diet was started 2.3 days after surgery and the median hospital stay was 5 days(range, 2-26 days). Among 71 patients with over 6 months follow-up, 69 patients (97.2%) were completely continent at 6 months after surgery and 29 patients(40.8%) were completely continent at catheter removal. In 58 patients who were younger than 65 years, potent preoperatively, and received a nerve sparing procedure, 31 patients(53.4%) were potent at 6 months after surgery. CONCLUSIONS:We were able to verify the feasibility and safety of RLRP in the management of prostate cancer. A longer follow-up of the data and larger prospective studies are necessary to confirm these resultsope

Robot-assisted Laparoscopic Partial Nephrectomy

PURPOSE: Laparoscopic partial nephrectomy is a treatment option for small renal masses. However, such time-consuming techniques such as tumor excision, hemostasis and intracoporeal suturing are still challenging procedures even for experienced laparoscopists. Incorporation of a robotic system would facilitate tumor excision, hemostasis and intracoporeal suturing. Herein, we review our technique and the short term outcomes for robot-assisted laparoscopic partial nephrectomy(RLPN). MATERIALS and METHODS: Eleven patients underwent RLPN for small renal masses. RLPN were performed with the da Vinci(R) robot system(Intuitive Surgical, Sunnyvale, USA) with three robot arms. In 7 cases, the renal hilum was clamped. Tumor excision and intracorporeal suturing were performed entirely with the robotic system. The specimen was extracted through the extended umbilical port incision. RESULTS: The mean tumor diameter was 2.5+/-1.5cm. The mean operative time was 179.5+/-49.4 minutes and the mean estimated blood loss was 354.5+/-440.7ml. The mean warm ischemia time was 30.4+/-5.9 minutes for 7 patients. There were no major complications. The surgical pathology showed clear cell type renal cell carcinoma in 7, papillary type renal cell carcinoma in 1, angiomyolipoma in 2 and lipoma in 1. There were no positive surgical margins. The mean hospital stay was 4.2+/-1.3 days. No recurrence had been observed after 3 to 18 months of follow-up. CONCLUSIONS: We were able to verify the feasibility and safety of using a RLPN in the management of small renal masses. Longer follow-up data and larger prospective studies are necessary to confirm these results.ope

Hybrid Transvaginal Gastro-Endoscopic Nephrectomy in a Porcine Model

This animal experimental study reports one case of hybrid transvaginal natural orifice transluminal endoscopic surgery (NOTES) for nephrectomy. We performed a nephrectomy through a transvaginal access and 2 additional 5 mm trocars in the abdomen by using the keyhole technique. The specimen was removed through the vaginal tract. The total procedure time was 102 minutes. There were no intraoperative complicationsope

Learning Curve for Robot-Assisted Laparoscopic Radical Prostatectomy for Pathologic T2 Disease

PURPOSE: To investigate the learning curve for robot-assisted laparoscopic radical prostatectomy (RALP) for pathologic T2 disease, we examined differences in perioperative outcomes according to time period. MATERIALS AND METHODS: Between July 2005 and June 2008, a total of 307 consecutive patients underwent RALP for prostate cancer and 205 patients had pathologic T2 disease. Patients were grouped into 6-month time periods. We collected and examined the patient's perioperative data including age, body mass index (BMI), prostate-specific antigen (PSA), operation time, estimated blood loss, and positive surgical margin. RESULTS: There were no significant differences among the groups in age (p=0.705), BMI (p=0.246), PSA (p=0.425), or prostate volume (p=0.380). Operation time (p<0.001) and estimated blood loss (p<0.001) decreased significantly with time. The positive surgical margin rate also showed a decreasing trend, but this was not significant (p=0.680). CONCLUSIONS: Operation time and estimated blood loss had a steep learning curve during the early 24 cases and then stabilized. A positive surgical margin rate, however, did not have a significant learning curve, although the positive surgical margin decreased continuouslyope