A Study on the Analysis and Structural Improvement of Electrically Damaged High-tension Line Duct in Electrostatic Precipitator

학위논문 (석사) -- 서울대학교 대학원 : 공학전문대학원 응용공학과, 2021. 2. 김용권.전기집진기는 석탄화력발전소에서 석탄 연소 후 배출되는 먼지의 99.8% 이상을 포집하는 대표적인 환경설비이다. 최근 미세먼지 주의보가 발령되면 화력 발전 출력의 80%를 넘지 못하는 화력 발전 상한 제약이 발령될 정도로 규제가 강화되고 있으며, 미세먼지에 대한 전 국민적 관심과 함께 미세먼지 저감을 위한 활동이 점차 강화되고 있다. 본 연구에서는 액화천연가스(LNG) 발전소와 비교해도 탄소 배출량이 크게 높지 않은 친환경 기술로, 출력은 원자력발전소 1기에 해당하는 1000[MW] 초초임계압 발전소가 건설되면서 전기집진기도 대용량으로 확장되고, 코로나 방전을 위한 정류형 변압기는 소형 경량화로 신기술이 적용되면서 발생한 고전압관 절연애자 파손 사례를 바탕으로 전기적인 파손원인을 분석하고, 고전압관 구조 개선 후 현장실험을 통해 문제를 해결하였다. 기존 정류형 변압기와 신형 정류형 변압기의 구조 검토를 통해 결로 발생 고전압관에서 절연애자의 파손이 발생한다는 공통점을 확인하고 다양한 가설을 검증하는 과정으로 연구를 진행하였다. 고전압관 결로 발생 메커니즘을 분석하고 원인을 제거하기 위한 현장실험과 관찰을 통해서 최적의 구조를 확인하고 24개 전체 정류형 변압기에 설치하여 모두 습기 발생 없이 개선됨을 검증하였다. 또한, 절연애자 파손원인을 분석하기 위해 COMSOL Multiphysic를 이용한 직류 전계해석을 통해 실제 현장의 절연애자 파손 부위와 시뮬레이션 결과를 비교하여 일치함을 확인하고, 전기적 파손원인을 개선하여 전기집진기의 안정적인 설치와 운전에 기여할 수 있었다. 본 연구에서 도출된 정류형 변압기의 고전압관 구조는 전국의 신규 건설 중인 1000[MW]급 전기집진기에 적용되어 결로 발생 및 절연애자 파손 문제를 개선하고 안정적으로 운전하며 신뢰성을 검증하였다.The electrostatic precipitator is a typical environmental facility that collects more than 99.8% of the dust emitted after burning coal in coal-fired thermal power plant. Recently, the upper limit of thermal power generation, which is not allowed to exceed 80 percent of thermal power output when a fine dust warning is issued, strengthening activities to reduce fine dust along with public interest in fine dust. In this study, the application of eco-friendly technology does not significantly increase carbon emissions compared to liquefied natural gas (LNG) power plants, and the problem of electrostatic precipitator caused by the construction of 1000 [MW] USC power plants corresponding to the output of one nuclear power plant is studied. Based on the case of damage of high-voltage duct porcelain insulator caused by the application of new technology that increases the volume of electrostatic precipitator to large capacity and the rectified transformer for corona discharge, the cause of electrical damage was analyzed and the improvement of high-voltage duct structure was solved through field experiments. Through the structural review of existing rectified transformers and new rectified transformers, the research was conducted in the process of verifying various hypotheses, confirming the common point of breakage of Porcelain insulator in condensation-producing high voltage duct. The mechanism of high-voltage duct condensation generation was analyzed and the optimal structure was checked through field experiments and observations to eliminate the cause, and all were installed in 24 whole rectified transformers to verify that they were improved without moisture generation. In addition, DC electric field analysis using COMSOL Multiphysics to analyze the causes of breakage of the insulator confirmed that it was consistent with the broken insulation at the actual site, and the causes of electrical damage could be verified and improved, contributing to the stable installation and operation of the electrostatic precipitator. The high-voltage duct structure of rectified transformers derived from this study was applied to the 1000 [MW] class electrostatic precipitator under new construction nationwide to improve the problem of condensation generation and insulator breakage, operate stably and verify reliability.제 1 장 서론 1 1.1 연구배경 및 목표 1 1.2 연구보고서 구성 3 1.3 전기집진기 구성 4 제 2 장 고전압관 절연애자 손상 사례 13 2.1 파손경과 및 증상 13 2.2 전기집진기 습기 발생 원인 19 2.3 전계해석 과정 24 2.4 온도와 전계의 상관관계 31 제 3 장 고전압관 구조 개선 실험 32 3.1 구조 개선 실험조건 및 방법 32 3.2 구조 개선 실험 결과 32 제 4 장 직류전계분포 시뮬레이션 38 4.1 COMSOL Multiphysics 시뮬레이션 조건 및 방법 38 4.2 시뮬레이션 시험 결과 44 제 5 장 결론 52 참고문헌 56 Abstract 58Maste

Neuroprotective Effect of Phenytoin and Hypothermia on a Spinal Cord Ischemic Injury Model in Rabbits

BACKGROUND: Spinal cord ischemic injury during thoracic and thoracoabdominal aortic surgeries remains a potentially devastating outcome despite using various methods of protection. Neuronal voltage-dependent sodium channel antagonists are known to provide neuroprotection in cerebral ischemic models. This study was designed to compare the neuroprotective effects of phenytoin with those of hypothermia in a rabbit model of spinal cord ischemia. MATERIAL AND METHOD: Spinal cord ischemia was induced in New Zealand white rabbits by means of infrarenal aortic cross clamping for 25 minutes. Four groups of 8 animals each were studied. The control group and the hypothermia group received retrograde infusion of saline only (22degrees C, 2 mL/min); the normothermic phenytoin group and the hypothermicphenytoin group received retrograde infusion of 100 mg of phenytoin at different rectal temperatures (39degrees C and 37degrees C, respectively) during the ischemic period. The neurologic function was assessed at 24 and 72 hours after the operation with using the modified Tarlov criteria. The spinal cords were harvested after the final neurologic examination for histopathological examination to objectively quantify the amount of neuronal damage. RESULT: No major adverse effects were observed with the retrograde phenytoin infusion during the aortic ischemic period. All the control rabbits became severely paraplegic. Both the phenytoin group and the hypothermia group had a better neurological status than did the control group (p<0.05). The typical morphological changes that are characteristic of neuronal necrosis in the gray matter of the control animals were demonstrated by means of the histopathological examination, whereas phenytoin or hypothermia prevented or attenuated these necrotic phenomena (p<0.05). The number of motor neuron cells positive for TUNEL staining was significantly reduced, to a similar extent, in the rabbits treated with phenytoin or hypothermia. Phenytoin and hypothermia had some additive neuroprotective effect, but there was no statistical significance between the two on the neurological and histopathological analysis. CONCLUSION: The neurological and histopathological analysis consistently demonstrated that both phenytoin and hypothermia may afford significant spinal cord protection to a similar extent during spinal cord ischemia in rabbits, although no significant additive effects were noticed.배경: 흉부 및 흉복부 대동맥의 수술 중 대동맥 차단은 허혈성 척수 손상에 의한 하반신 마비와 같은 심각한 합병증을 유발할 수도 있어 수술 중 허혈성 척수손상을 예방하기 위한 여러 방법의 연구가 계속 되고 있다. 최근에 허혈성 대뇌 손상 모델에서 신경조직의 막전위 의존성 나트륨채널 길항제가 대뇌 보호 효과가 있다는 보고가 있다. 본 연구는 토끼의 허혈성 척수손상 모델에서 나트륨채널 길항제인 페니토인과 저체온의 척수보호효과를 비교해 보고자 시행되었다. 대상 및 방법: 뉴질랜드산 토끼의 신동맥직하부에서 복부대동맥을 25분간 차단하는 방식으로 척수허혈을 유도하였으며 각 군당 8마리씩 네 군으로 나누었다. 대조군과(S39) 저체온군은(S37) 대동맥 차단시간 동안 직장온도를 각기 39oC와 37oC로 일정하게 유지하면서 22oC 생리적 식염수만 2 mL/min 의 속도로 연속 주입하였으며, 정상체온 및 저체온 페니토인 군은(P39, P37) 앞의 두 군과 동일한 방법으로 하되 생리적 식염수에 페니토인을 녹여 주입하였다(100 mg/50 mL). 수술 후 24시간 및 72시간이 경과한 다음 Tarlov scoring을 통해 신경학적 평가를 시행하였고 마지막 평가 후에는 객관적으로 신경손상의 정도를 정량 화하기 위해 척수를 고정 처리하였다. 결과: 페니토인의 역행성 주입에 따른 심각한 문제는 없었으며 대조군에(S39) 속한 모든 동물은 완전 또는 심한 하반신 마비 소견을 보였다. 페니토인과(P39) 저체온(S37)군 모두 대조군에 비해 신경학적 평가는 유사한 정도로 우수한 결과를 보였다(p＜0.05). 조직 병리학적 검사 결과, 대조군에 속한 모든 동물은 척수 회백질에서 심한 신경조직 괴사 때 보이는 전형적인 특징을 보여주었으며, TUNEL 염색에 양성인 신경세포도 높은 빈도로 관찰되었으나, 저체온 또는 페니토인 투여 군에서는 괴사현상이 유의한 정도로 감소하였으며, 상대적으로 매우 낮은 빈도의 TUNEL 염색 양성세포가 관찰되었다(p＜0.05). 그러나 저체온과 페니토인을 병용했을 때의 부가적인 척수보호효과를 조사해 본 결과 신경학적 평가와 조직병리학적 결과 모두 유의한 수준의 부가적인 효과는 없었다. 결론: 결론적으로, 토끼의 허혈성 척수 손상 모델을 이용하여 페니토인과 저체온의 신경보호효과를 알아본 결과 신경학적 평가와 조직병리학적 검사 결과 모두 부가적인 효과는 보여주지 못했지만 각각의 경우 유사한 정도의 신경보호효과를 보여주었다

The Prognostic Significance of Neuroendocrine Differentiation for Treating Prostatic Carcinoma in 699 Cases of Radical Prostatectomy

BACKGROUND: Neuroendocrine differentiation of prostatic carcinoma is known to be associated with a poor prognosis, tumor progression and androgen-independency, and there is currently no successful therapy for this type of tumor. The purpose of this study is to evaluate the prognostic implications of neuroendocrine differentiation in prostatic carcinoma in Korean men. METHODS: Six hundreds and ninety nine consecutive cases of radical prostatectomy specimens were systematically processed for topographic mapping. Neuroendocrine differentiation was detected by immunohistochemistry by using antibody to chromogranin. We analyzed the relationship between neuroendocrine differentiation and the clinicopathological prognostic factors, as well as biochemical failure. The neuroendocrine differentiation was evaluated according to the presence of chromogranin-positive cells, the pattern of neuroendocrine cells and the number of neuroendocrine cells, respectively. RESULTS: Neuroendocrine differentiation was detected in 150 out of 699 cases (21.5%). The presence of neuroendocrine differentiation as well as the pattern of neuroendocrine cells was correlated with biochemical failure and the other clinicopathological prognostic factors such as the Gleason score, the pathologic stage, the tumor volume, angiolymphatic invasion, perineural invasion, and the Ki-67 proliferative index (p<0.05). CONCLUSIONS: We suggest that neuroendocrine differentiation of prostatic carcinoma is a prognostic factor even in radical prostatectomy specimens for localized prostate cancer. Evaluation of the presence of neuroendocrine differentiation as well as the pattern of neuroendocrine cells is recommended in radical prostatectomy specimens.이 논문은 분당서울대학교병원 일반연구비에 의해 이루어진 것임(02-2007-012)

Prognostic Significance of the Tumor Volume and Tumor Percentage for Localized Prostate Cancer

PURPOSE: Tumor volume has been thought to be an important predictive factor for significant prostate cancer. We assessed the impact of the tumor volume(TV) and the tumor percentage(TP) of radical prostatectomy specimens on the pathological variables and the oncological outcome. MARERIALS AND METHODS: The tumor percentage and tumor volume were calculated for 525 cases by a single pathologist who determined the volume based on the surface area of the slides involved by tumor of the prostate. Univariate and multivariate logistic regression analyses were used to characterize the association of TP categories(20%) and TV(7.5cc) with the clinicopathological variables. Biochemical recurrence(BCR) was estimated using Kaplan-Meier analysis and Cox's hazard regression model. RESULTS: The mean prostate cancer volume was 6.5+/-8.5cc(median: 3.8, range: 0.04-73.8) and the mean percent tumor composition was 0.17+/-0.19 (median: 0.1, range: 0.01-0.95). A higher tumor volume and a higher tumor percentage were associated with extra-capsular extension(ECE), a positive surgical margin(PSM), a higher pT stage and a higher prostate-specific antigen(PSA) Gleason score(all p<0.05). In addition, TP was the independent predictor of ECE(adjusted odds ratio(OR): 22.66, 95% confidence interval(CI): 1.801-285.079, p=0.016), but the tumor volume was not associated with ECE on the multivariate logistic analyses. On the Kaplan-Meier analysis, but not on the Cox-hazard analyses, the TP did demonstrate a significant association with biochemical recurrence(p=0.035), yet the TV did not reach statistical significance(p=0.190). CONCLUSIONS: Our data indicates that the tumor percentage had a significant effect on the BCR on the Kaplan-Meier analysis. The tumor percentage rather than the tumor volume might be more useful to predict the prognosis of prostate cancer

Pathologic Outcome of Unilateral Low Risk Prostate Cancers on Multicore Prostate Biopsy after Radical Prostatectomy

PURPOSE: To investigate clinicopathologic characteristics of unilateral, low risk prostate cancers detected via multi(>or=12)-core prostate biopsy. MATERIALS AND METHODS: One hundred four patients who underwent radical retropubic prostatectomy(RRP) for unilateral, low risk prostate cancer (clinical stage or=12)-core prostate biopsy were enrolled. In this retrospective study, we reviewed the patients' preoperative and pathologic data to assess potential predictors of pT2c or greater disease at the time of RRP, as well as characteristics of such disease. RESULTS: Of the 104 subjects, only 34(32.7%) were pathologically-proven to have unilateral disease, while the others showed pathologically-bilateral or worse disease from analysis of the RRP specimens. Subjects pathologically found to have uni- and bi-lateral disease showed no significant differences regarding age, prostate-specific antigen(PSA), free-to-total PSA ratio, prostate volume, clinical stage, number of positive cores, biopsy Gleason score, number of total biopsy sites, and highest percentage of tumor at any biopsy site. Multivariate logistic regression analysis revealed no significant preoperative predictors of pT2c or greater disease at RRP. CONCLUSIONS: Most patients with unilateral, low risk prostate cancer detected on multi(>or=12)-core prostate biopsy actually had pathologically- worse disease. For clinically-localized prostate cancer, a more accurate method to identify appropriate candidates for unilateral or focal ablative therapy should be developed

Prognostic Significance of Multifocal Tumor in Radical Prostatectomy

Purpose: We investigate the impact of tumor multifocality on the biochemical recurrence rate after radical prostatectomy. Materials and Methods: Data was collected from 525 patients who underwent radical prostatectomy for clinically localized prostate cancer from 2003 to 2007. We evaluated the potential associations of multifocality with various clinical and pathologic factors. The ability to predict extra-capsular extension (ECE) was tested by logistic regression models, whereas biochemical recurrence (BCR) was assessed via Kaplan-Meier analyses and Cox-hazard regression models. The BCR was defined as a level of serum prostate-specific antigen (PSA) of 0.2ng/ml or greater on consecutive evaluations. Results: Multifocality was observed to be significantly associated with the presence of a high grade Gleason pattern (p=0.014), the pT stage (p＜ 0.001), ECE (p=0.005) and a positive surgical margin (PSM) (p=0.019). Moreover, it was the independent predictor of ECE on multivariate logistic regression analyses (p=0.039). However, although multifocality had a significant influence on biochemical recurrence on the Kaplan-Meier analyses (log rank test, p=0.019), only the PSA level and the Gleason score were significant predictors of BCR on the multivariated Cox-hazard analyses. Conclusions: Although multifocality was associated with adverse pathologic features, it had no significant effect on biochemical recurrence on the multivariated cox-hazard analyses

8-Cl-cAMP가 유도하는 암세포의 세포성장억제 과정에서 작용하는 Akt2와 SHC1 단백질의 기능에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 협동과정 유전공학전공, 2014. 2. 홍승환.Cyclic AMP is a secondary messenger which plays a critical role(s) in various cellular physiological functions including regulation of cell growth and death. 8-chloro-cyclic AMP (8-Cl-cAMP) is one of the site-selective cAMP analogs that induce growth inhibition, apoptosis, differentiation and reverse transformation in a broad spectrum of cancer cell lines. Although 8-Cl-cAMP promotes tumor cell-specific growth inhibition and apoptosis, the exact signaling pathways for its action are still uncertain. Many research groups have made an effort to elucidate the signal pathways of 8-Cl-cAMP-induced cancer cell specific growth inhibition and apoptosis. Through several studies, we knew that 8-Cl-cAMP promotes the down-regulation of RI subunit of PKA, the activation of protein kinase C (PKC), Rap1, AMP-activated protein kinase (AMPK) as well as the p38 mitogen activated protein kinase (p38 MAPK) during the growth inhibition or apoptosis of cancer cells. Also, it was confirmed that the conversion of 8-Cl-cAMP to 8-Cl-adenosine is prerequisite for its cell growth inhibitory effects. In this thesis, I tried to show that Akt/protein kinase B (PKB) as well as Src homology 2 domain containing transforming protein 1 (SHC1) proteins were involved in 8-Cl-cAMP-induced cancer cell growth inhibition. Akt/PKB genes encode three isoforms, Akt1, Akt2 and Akt3, which belong to the serine/threonine-specific protein kinase family. Akt/PKB protein has been known for its ability to confer cells to enhance cell survival by inhibiting apoptosis. Accordingly, it is expected that the activation or phosphorylation of Akt/PKB would be decreased upon treatment with 8-Cl-cAMP. Contrary to the expectations, however, the phosphorylation of Akt/PKB was increased by treatment with 8-Cl-cAMP. The increased phosphorylation of Akt/PKB was repressed by treatments of ABT702 (an adenosine kinase inhibitor) and NBTI (an adenosine transporter inhibitor). Furthermore, the 8-Cl-cAMP-induced phosphorylation of Akt/PKB was not attenuated by the treatments of Compound C (an AMPK inhibitor), AMPK-DN (AMPK-dominant negative) mutant and SB203580 (a p38 MAPK inhibitor), whereas TCN (an Akt1/2/3 specific inhibitor) and an Akt2/PKB-targeted siRNA repressed the 8-Cl-cAMP- and 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR, an AMPK activator)-mediated phosphorylation of AMPK and p38 MAPK. TCN also restored the growth inhibitory effect mediated by 8-Cl-cAMP and AICAR, whereas, the Akt1/PKB-targeted siRNA did not reduce the 8-Cl-cAMP-induced phosphorylation of AMPK and p38 MAPK. The obtained results pointed to the direction that the treatments of 8-Cl-cAMP and AICAR increased the phosphorylation of Akt2/PKBβ, which in turn stimulated the activation of AMPK and p38 MAPK. SHC1 protein is expressed as three isoforms, 46, 52 and 66 kDa, which belong to the adaptor protein containing Src homology 2 (SH2) domains and each isoform has been shown to exert different functions in cellular response. In this thesis, it was shown that the treatment of 8-Cl-cAMP to cancer cells lower the phosphorylation level of SHC1, whereas the total amount of SHC1 protein was not altered. Furthermore, Compound C (an AMPK inhibitor) and SB203580 (a p38 MAPK inhibitor) did not block the 8-Cl-cAMP-induced decrease of SHC1 phosphorylation. However, when SHC1-targeted siRNAs were introduced in order to mimic the decrease of SHC1 phosphorylation, the decreased phosphorylaton and total amount of SHC1 protein seemed to stimulate the phosphorylation of AMPK and p38 MAPK similar to 8-Cl-cAMP treatment. These results suggest that reduced level of SHC1 phosphorylation acted upon the phosphorylation of AMPK and p38 MAPK as an upstream regulation factor during 8-Cl-cAMP-induced growth inhibition.ABSTRACT i TABLE OF CONTENTS v LIST OF FIGURES AND TABLES vii INTRODUCTION 1 MATERIALS AND METHODS 18 RESULTS 24 PART1. Role of Akt2/protein kinase B β (PKBβ) in 8-Cl-cAMP-induced cancer cell growth inhibition 24 1. Treatment with 8-Cl-cAMP and AICAR induce the increased phosphorylation of Akt/PKB. 24 2. Anti-proliferative properties of 8-Cl-cAMP are confined to cancer cells. 35 3. Akt/PKB seems to promote the activation of AMPK and p38 MAPK during 8-Cl-cAMP- or AICAR-induced growth inhibition. 40 4. The Akt/PKB specific inhibitor, TCN, blocked the growth inhibition and cell death mediated by 8-Cl-cAMP. 51 5. Akt2/PKBβ plays a role as upstream factor of AMPK and p38 MAPK during 8-Cl-cAMP-induced growth inhibition. 52 PART 2. Role of SHC1 protein in 8-Cl-cAMP-mediated cancer cell growth inhibition 64 1. The phosphorylation of SHC1 protein in cancer cells was decreased when treated with 8-Cl-cAMP. 64 2. The decrease of SHC1 phosphorylation is limited to cancer cells and not non-transformed cells. 75 3. The decrease of SHC1 protein levels plays a role in responsiveness to 8-Cl-cAMP-induced growth inhibition. 75 DISCUSSION 86 REFERENCES 96 ABSTRACT IN KOREAN 107 ACKNOWLEDGEMENT 111Docto

Flux-Weakening Control of IPMSM for Improving Torque Capability

학위논문 (석사)-- 서울대학교 대학원 : 전기. 컴퓨터공학부, 2011.2. 설승기.Maste

Effect of suramin and galactose on differentiation of human stomach cancer cell lines

학위논문(박사)--서울대학교 대학원 :의학과 병리학전공,1996.Docto

초대칭 현상론의 두 가지 주제 : 플레버 문제의 부가차원적 고찰 및 빅뱅 재가열 온도의 범위

Thesis(doctoral)--서울대학교 대학원 :물리학부,2005.Docto