800MPa 고강도 원형 강관 접합부의 거동 및 강도 산정식 개발

학위논문 (석사)-- 서울대학교 대학원 : 건축학과, 2016. 2. 이철호.Nowadays circular hollow sections are increasingly used in a wide range of building and offshore structures due to its attractive structural and architectural properties. The use of high-strength steel tubular members can bring about many technological advantages from design to erection. However, most of current design standards including KBC 2009 forbid the use of hollow sections whose yield stress and yield ratio are higher than 360MPa and 0.8, respectively. These limitations appear an unduly conservative technical barrier, and their validity needs to be re-evaluated experimentally and analytically. In this study, a total of 17 full-scale T- and X-Joints of ordinary and high-strength steel circular hollow sections were tested and analyzed to examine the extendability of current design standards. The objective of the present study is not only to extend the understanding to the high-strength steel CHS joints, but also to form the basis of the application of high-strength steel to CHS joints in practice. The key test variables include the strength of steel and geometrical configuration of each joint. The rational to extend the applicability of current design standards was proposed. The CHS joints are investigated numerically using the general purpose finite element (FE) tool ABAQUS, based on the detailed calibration against reported test results. Parametric study is conducted on X- and T-Joints. Combining the results of experimental and numerical parametric study has led to new ultimate strength formulations for X- and T-Joints made of high-strength steel which may serve as a basis for future design recommendations.Chapter 1.Introduction 1 1.1.Research background 1 1.1.1.Joint configuration 1 1.1.2.General failure criteria 3 1.1.3.General failure modes 4 1.2.Limitations of Current Design Provisions for Circular Hollow Section Joints 7 1.2.1.Limitations on geometric parameters 7 1.2.2.Limitations on materials 7 1.3.Design Formulation for Static Strength of CHS Joints 9 1.4.Previous Relevant Studies 13 1.4.1.Ring model 13 1.4.2.Previous Research on CHS Joints 16 1.5.Research motivation and scope 17 Chapter 2.Experimental Behavior of CHS Joints 19 2.1.Introduction 19 2.2.Material tests 19 2.2.1.Introduction for material tests 19 2.2.2.Mechanical properties 19 2.3.CHS X-Joints 21 2.3.1.Experimental program 21 2.3.2.Test measurements and procedure 27 2.3.3.Results of the static tests 35 2.4.CHS T-Joints 45 2.4.1.Experimental program 45 2.4.2.Test measurements and procedure 45 2.4.3.Results of the static tests 53 Chapter 3.Verification of Finite Element Analysis for CHS Joints 60 3.1.Introduction 60 3.2.FE considerations 61 3.2.1.Consideration of initial geometry imperfection 61 3.2.2.Presence of welds 63 3.2.3.Element types 65 3.2.4.Mesh sensitivity study 67 3.2.5.Boundary conditions and loading 70 3.3.Verification 72 3.3.1.Material input 72 3.3.2.X-Joints 73 3.3.3.T-Joints 74 3.4.Summary 74 Chapter 4.Numerical Parametric Study of CHS Joints 77 4.1.Introduction 77 4.1.1.Design of numerical parametric study models 77 4.2.X-Joints 79 4.2.1.Effect of α factor 79 4.2.2.Numerical results 79 4.2.3.New design formula proposal and validation 97 4.3.T-Joints 105 4.3.1.Effect of α factor 105 4.3.2.T-joints excluding chord bending effect 106 4.3.3.T-joints including chord bending effect 112 4.3.4.New design formula proposal and validation 125 4.4.Summary 131 Chapter 5.Summary and Conclusion 133 References 135 국문초록 137Maste

무작위로 위치한 다수 도청자가 존재하는 전이중 중계 시스템의 보안 성능

학위논문 (석사)-- 서울대학교 대학원 공과대학 전기·정보공학부, 2017. 8. 이재홍.Full-duplex (FD) operation improves the spectral efficiency of a relay system where the relay simultaneously transmits and receives signals on the same channel. The performance of FD relay systems is limited by self-interference, i.e., signal leakage from the relays transmit antenna to its receive antenna. However, in the FD relay system with malicious eavesdroppers, simultaneous transmission from the source and relay confuses the eavesdroppers. In this thesis, we investigate a FD relay system where a source communicates with a destination via a decode-and-forward relay in the presence of randomly located eavesdroppers. We derive analytical expressions for the secrecy outage probability and the average secrecy rate of the system. Simulation results show that the secrecy performance of the system is improved as the density of eavesdroppers decreases. It is also shown that the FD re-lay system has higher secrecy performance than the half-duplex relay system when a large portion of self-interference is cancelled.본 논문에서는 무작위로 위치한 다수 도청자가 존재할 때 복호 후 전송 전달 방식을 사용하는 전이중 중계기를 통해 송신기와 수신기가 통신하는 전이중 중계 시스템에 대해 연구한다. 송수신기 사이의 단대단 신호대간섭잡음비와 가장 해로운 도청자에서 신호대간섭잡음비의 누적분포함수를 유도하여 시스템의 보안 불능 확률과 평균 보안 전송률을 분석한다. 모의 실험을 통해 시스템의 보안 불능 확률과 평균 보안 전송률의 분석 결과가 실험 결과와 일치함을 확인한다.Chapter 1 Introduction 1 Chapter 2 System Model 5 Chapter 3 Secrecy Performance Analysis 11 3.1 SINR Distribution 12 3.2 Secrecy Outage Probability 17 3.3 Average Secrecy Rate 20 Chapter 4 Simulation Results 22 Chapter 5 Conclusion 38Maste

Detection and identification of mycobacterium tuberculosis in clinical specimens by polymerase chain reaction

의학과/박사[한글] 결핵의 진단은 환자의 임상증상 및 X-선소견과 아울러 가검물에서 결핵균(Mycobacterium tuberculosis)을 분리하여 확진한다. 그러나 가검물에서 결핵균을 분리하여 동정하기가지는 4∼8주간의 시일이 소요되며 민감도에 있어서도 미흡한 점이 있어 화학요법치료의 지연을 초래하게된다. 최근 분자생물학기법의 발달로 DNA의 특정부분을 시험관내에서 증폭하여 검출하는 중합효소 연쇄반응(polymerase chain reaction; PCR)법이 개발되었으며, PCR을 이용하여 결핵균 DNA를 특이성과 민감도가 높으며, 신속하게 검출할 수 있는 방법이 보고되었다. 그러나 환자나 건강대조군의 가검물을 대상으로 PCR을 시행하여 결핵의 진단이나 환자의 치료 후 관리에 응용한 보고가 없어 실제로 임상에서 PCR을 이용한 결핵 진단의 가능성은 아직 알려지고 있지 않다. 따라서 본 연구에서는 M. tuberculosis complex에 속하는 mycobacteria의 DNA에 10-16곳에 존재하는 Is6110 repetitive sequence에 근거한 123bp 단편을 증폭하는 PCR법을 이용하여 폐결핵환자 및 기타 호흡기 질환 환자의 가검물에서의 PCR 결과와 환자의 임상관찰과 배양결과를 비교하여 결핵의 진단에 PCR의 응용가능성을 평가하고자 하였으며, 그 결과는 다음과 같다. 1. 결핵균을 포함한 4종의 mycobacteria 및 기타 세균의 DNA를 분리하여 PCR을 시행한 결과 Is6110 DNA의 123bp 단편이 M. tuberculosis complex에 속하는 mycobacteria에서만 증폭되어 본 연구에서 이용한 primer에 의한 PCR이 결핵균을 특이하게 검출할 수 있음을 보였다. 2. 가검물에서 검출되는 123bp DNA산물과 결핵균 DNA에서 PCR을 이용하여 증폭한123bp를 (32)**P 로 표지하여 DNA hybridization을 시행한 결과 가검물에서 증폭되는 123bp가결핵균 DNA의 123bp와 일치함을 보여 가검물에 결핵균이 존재함을 알 수 있었다. 3. 가검물에 존재하는 결핵균 DNA를 분리하는 방법으로 bead-beating법, Iysozyme-sodium dodecyl sulfate-Geneclean법, 및 proteinase K법을 32개의 가검물을 대상으로 비교한 결과 검출률은 각각 90.6%, 90.6%, 84.4%로서, 민감도와 소요시간 및 간편성을 비교할 때 bead-beating법이 가장 우수하였다. 4. 가검물내의 결핵균 수를 산정한 후 10배수 계단 희석하여 bead-beating법으로 DNA를 분리하고 PCR을 시행한 결과 균수가 1∼10인 경우에도 증폭된 DNA를 관찰할 수 있었다. 5. 가검물을 대상으로 PCR을 시행한 결과 정상대조군 17명의 객담에서는 모두 PCR 음성이어서 본 연구에서 시행한 PCR의 특이도가 매우 높음을 알 수 있었다. 한편 활동성 폐결핵환자로 진단되어 치료중인 환자 117명 중 93명(79.5%)의 가검물에서 PCR법으로 결핵균 DNA 단편을 검출할 수 있었다. 이는 도말검사나 배양검사에 의한 결핵균 검출률 53.8%(117명 중 63명)보다 유의성 있게 높아 PCR법이 배양검사보다도 민감도가 높음을 알 수 있었다. 6. 비활동성 폐결핵 경력자중 재발이 의심되어 내원한 41명의 배양검사 음성인 가검물 중 16명(39%)에서 PCR법으로 결핵균 DNA를 검출할 수 있었다. 7. 결핵 이외의 호흡기 질환으로 내원한 환자의 가검물에서 PCR을 시행해본 결과 30명가운데 14명(46.7%)에서 PCR에 의해 결핵균 DNA가 검출되었으나 이들에 대한 임상 관찰 결과는 앞으로 추시해야 할 것으로 사료된다. 이상의 결과로 보아 결핵균에 특이하게 존재하는 Is6110 repetitive sequence에서 123bp DNA 단편을 증폭하는 PCR법은 임상 가검물에 존재하는 결핵균 DNA를 신속하고 특이하게 검출할 수 있으며, 민감도에 있어서도 결핵균 배양법보다 우수하여 PCR법이 결핵균의 실 험실진단방법으로 이용될 가능성을 보였다. 그러나 PCR법은 생존한 결핵균과 사멸한 것의 구별을 못하는 단점이 있으며, 미량의 결핵균의 존재와 임상증상의 발현과의 명확한 관계가 정리되지 않은 상태에서 PCR 결과를 결핵의 진단이나 환자의 치료 후 관리에 응용하기 위해서는 보다 많은 전향적인 연구가 진행되어야 할 것으로 사료된다. [영문] Recent development in the polymerase chain reaction(PCR) technology has brought an extraordinary opportunity for the rapid detection of Mycobacterium tuberculosis in clinical specimens for the diagnosis of tuberculosis. DNA segment which is specific to M. tuberculosis was detectable in matter of hours and DNA from one to 10 organisms appeared positive by PCR. However, the PCR tools have not been evaluated using clinical specimens from tuberculosis patients and controls. Even DNA preparation methods have net been clearly eatablished. This study was, therefore, initiated to explore the efficient M. tuberculosis DNA preparation methods from clinical specimens and to evaluate the PCR tools for the diagnosis of pulmonary tuberculosis. The primers amplifying the 123 bp segment of the IS6110 repetitive sequence of the M. tuberculosis DNA were used in PCR. Clinical specimens from the active pulmonary tuberculosis patients, inactive cases and controls were examined for the presence of M. tuberculosis DNA by PCR and the results were then compared with bacteriological and clinical findings. The results obtained were as follows: 1. As a result of PCR after DNA preparation of M. tuberculosis, three other mycobacteria and other bacteria, the 123 bp DNA fragment based on Is6110 was amplified specifically from M. tuberculosis complex. PCR thus was a useful method for the detection of M. tuberculosis. 2. Dot blot hybridization of PCR products from clinical specimens with (32)**P-labeled 123 bp DNA fragments Prepared from M. tuberculosis chromosomal DNA as a probe showed a positive reaction. This indicated that m. tuberculosis were present in the clinical specimens. 3. When the M. tuberculosis DNA from clinical specimens were isolated by bead-beating, Iysozyme-sodium dodecyl sulfate-Geneclean and proteinase K method, the detection rates were 97.6%,90.6% and 84.4%, respectively and the bead-beating method gave the best sensitivity and rapidity. 4. As the results performed PCR after DNA isolation by bead-beating method, the sensitivity was one to ten organisms of M. tuberculosis. 5. Clinical samples from 211 patients presented to the chest clinic at a teaching hospital and 17 samples from normal controls were examined for the presence of m. tuberculosis DNA by PCR and the results were then compared with bacteriological and clinical findings of patients and controls. None of normal controls were PCR positive, thus indicating the high specificity of PCR. Of 117 patients with active pulmonary tuberculosis,93(79.5%) were PCR positive; in contrast, only 63(53.9% ) were culture positive. 6. Sixteen(39% ) of 41 inactive pulmonary tuberculosis with culture negative who were suspected having reinfection had detectable m. tuberculosis DNA by PCR. 7. Fourteen(46.7% ) Patients with 30 Pulmonary diseases without tuberculosis had detectable M. tuberculosis DNA by PCR, but it is necessary to perform follow-up study on these patients. These results thus showed that the PCR method amplifying the 123 bp fragment was highly sensitive and specific in detecting the M. tuberculosis DNA in clinical specimens; however, the significance of PCR positive results remains to be determined in terms of detecting active pulmonary tuberculosis patients, particularly in the endemic areas of tuberculosisrestrictio

Studies on identification and during resistance of atypical mycobacteria isolated from patients with pulmonary tuberculosis

의학과/석사[한글] 토양이나 수중에 널리 분포되어 있는 비정형 항산균(인형, 우형결핵균 및 나균은 제외)의 감염에 의해 야기되는 비정형 항산균증과 인형결핵균의 감염으로 인한 폐결핵의 감별진단은 이들 환자들로부터 항산균의 분리배양 및 동정에 의해서만 가능하다. 저자는 경기도 안양시 보건소에 등록되어 있는 폐결핵 환자를 대상으로 하여 채취된 객담으로부터 비정형 항산균의 분리배양을 시도하였다. 또한 분리 배양된 비정형 항산균의 생화학적 성상과 약제내성검사 및 임상적인 조사를 실시하여 다음과 같은 결론을 얻었다. 1. 총 334예에서 항산균 103주 (30.8%)를 분리 배양하였다. 2. 분리 배양된 항산균주로부터 비정형 항산균으로 감별된 균주는 10주(9.7%)이며 인형 결핵균은 93주(90.3%)를 분리하였다. 3. 동정된 비정형 항산균주를 Runyon 구별로 분류하면 암착색균군, 광비발색균군이 각각 3주(30.0%)씩이며, 발육신속균군이 4주(40.0%)였으며, 광발색균군은 한주도 분리되어 않았다. 4. 생물학적 성상 및 생화학적 특성시험 양상에 따라 암착색균군 3주중 2주는 Mycobacterium scrofulaceum, 1주는 Mycobacterium szulgai로, 광비발색균군 3주중 2주는 Mycobacterium avium complex, 1주는 Mycobacterium terrae complex로 동정되었으며, 발육신속균 군 4주중 3주는 Mycobacterium fortuitum, 1주는 Mycobacterium chelonei로 동정되었다. 5. 항결핵제에 대한 약제 내성검사에서 INH에서는 12주가 전부 내성을 나타내었으며, SM.EB.TB. 및 CS.의 저농도에서도 완전내성을 나타내었다. 그리고 EB.TH.CS. REP.의 고농도에서는 12주중 10주가 감수성을 나타내었다. 6. 비정형 항산균이 배균된 환자의 X-선 및 임상적 소견을 분석한 결과 인형결핵균 감염으로 인한 폐결핵 환자의 중상에 비해 경하지 않는 것으로 사료되었으며, 이들 환자들은 인형 결핵균 감염환자와 동일시 되어 장기간 치료되어 왔음으로 대부분 호전되지 못했다. [영문] The differential diagnosis of atypical mycobacteriosis caused by atypical mycobacteria(with the exception of Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium leprae) which are widely distributer in soil and water, from pulmonary tuberculosis is posible only when atypical mycobacteria are isolated and identified. In this investigation, attempts were made to isolate atypical mycobacteria from persons registered as tuberculosis patients in the Anyang Health center in Anyang city, Kyungki province, Korea. Biological and biochemical tests were performed for the atypical mycobacteria isolated from these patients. also retrospective analysis of clinical and X-ray findings of the patients with bacteriologically confirmed atypical mycobacteriosis were done. The results can be summarized as follows : 1. 103 strains of mycobacteria were isolated among 334 sputum samples from patients. 2. Among the isolated mycobacteria, 10 strains(9,7%) were found to be a atypical mycobacteria and 93 strains (90.3%) were tubercle bacilli of human type. 3. On the basis of Runyon's grouping of atypical mycobacteria, there were 3 strains(30.0%) of scotochromogen and nonphothchromogen respectively, 4 strains(40.0%) of rapid grower, and no photochromogen. 4. By biochemical tests, 3 strains of scotochromogen were identified as Mycobacterium scrofulaceum(2 strains) and Mycobacterium szulgai(1 strain), 3 strains of nonphotochromogen were Mycobacterium avium-complex(2 strains) and Mycobacteriosis(1 strain), and 4 strains of rapid grower were Mycobacteriosis fortuitum (3 strains) and Mycobacterium chelonei. 5. In drug sensitivity tests, all the isolated atypical mycobacteria showed resistance to various concentration of INH and low sonsentrations of SM, EB, TH, and CS. 10 strains were sensitivity to only high concentrations of EB, TH, CS, AND REP. 6. In analysis of clinical findings by the patients with bacteriologically confirmed atypical mycobacteriosis, it was found that clinical symptoms of these patients appeared not to be milder than those of patients with pulmonary tuberculosis. The patients with atypical mycobacteriosis had been treated for pulmonary tuberculosis for a long time and they showed no improvement.restrictio

Manganese(Ⅲ)-iodosylbenzene complex, preparation method thereof and oxidant comprising the same

본 발명은 3가 망간 이오도실벤젠 복합체, 이의 제조방법 및 이를 포함하는 산화제에 관한 것으로, 본 발명의 일 측면에서 제공되는 3가 망간 이오도실벤젠 복합체는, 우수한 친전자 반응성으로 사이클로헥사디엔, 다이하이드로안트라센 및 크산틴의 수소원자추출 (Hydrogen Atom Abstraction, HAA) 반응과, 티오아니솔 및 스틸벤의 산소원자이동 (Oxygen Atom Transfer, OAT) 반응을 유도할 수 있는 효과가 있다

다양한 환경하에서의 액체 구조와 성질에 관한 분자동력학적 모의실험

학위논문(박사) - 한국과학기술원 : 화학과, 2001.8, [ vii, 69 p. ]I have studied the structure and properties of liquid state using molecular dynamics simulations method. The major points I have dealt with are structural changes of water induced by an external electric field and the curvature dependence of the surface tension of argon liquid. At first, using molecular dynamics simulations with the rigid TIP4P water model, I have analyzed the structural change of liquid water induced by an external electric field. The temperature was controlled with a Nose-Hoover thermostat. From this simulation study, I found liquid water with the enhanced structural regularity by applying an electric field could be acquired. Through the simulations under various strengths of the electric field, I can see that the threshold for the significant structural change is thought to be between 0.2 and 0.15 V/Å. When the number of six-membered rings is increased by the external electric field, so that water is forced to have structural regularity, I calculate the diffusion coefficients and discover that water I make in the simulations is not solid but still liquid under the electric field. Secondly, I present the first molecular dynamics simulation study of vapor bubbles. Molecular dynamics simulations are carried out to examine the curvature dependence of the surface tension for argon vapor bubble as well as liquid droplet. Using the Irving-Kirkwood pressure tensor, I calculate the surface tension and the surface of tension by two thermodynamic methods. The results for the surface tension of droplet show that the surface tension decreases with decreasing droplet radius. On the other hand, the surface tension of vapor bubble increases with decreasing bubble radius.한국과학기술원 : 화학과

위성통신시스템의 점 과정 기반 모델링 및 분석

학위논문(박사) - 한국과학기술원 : 전기및전자공학부, 2024.2,[vii, 106 p. :]Satellite communications have recently been considered as a solution to deliver global internet services, leveraging extensive satellite coverage. As numerous satellites are set to be deployed, there is a growing need to investigate satellite mega-constellations from the perspective of system optimization. In this dissertation, we model and analyze various satellite communication scenarios based on point processes. First, we analyze low Earth orbit (LEO) satellite systems under the shadowed-Rician fading by modeling the satellite distribution based on a binomial point process (BPP). The analytical results are further simplified with the help of the Poisson limit theorem. Next, we derive the coverage performance of geosynchronous Earth orbit (GEO) satellite systems where GEO satellites are distributed in the geostationary orbit according to a BPP. We then introduce promising structures for clustering-based LEO constellations and evaluate performances at both link- and system-levels considering various clustering types and transmission schemes. The extensive coverage, a primary advantage of satellites, could also cause a significant risk by making uplink signals more susceptible to interception. In this regard, we analyze the impact of potential threats posed by malicious satellite eavesdroppers in terms of secrecy performance.한국과학기술원 :전기및전자공학부

Pyrococcus furiosus 에서 추출한 루브레독신의 열적 안정성에 대한 분자 동력학적 모의실험

학위논문(석사) - 한국과학기술원 : 화학과, 1996.2, [ iv, 41 p. ]The hyperthermostable protein, rubredoxin from Pyrococcus furiosus(RdPf) is 53-residue protein with a three-stranded anti-parallel β-sheet and several loops. The origin of the stability of the protein has been discussed in terms of electrostatic interactions by date. In this paper, the hydrophobic interaction of residues of the surface of the protein was investigated as well as electrostatic interactions. To investigate the effect of changes of electrostatic and hydrophobic interactions on the structure and dynamic property of RdPf, molecular dynamics simulations in solution were performed. Glu 14 has a backbone hydrogen bond with N-terminal and multiple electrostatic interactions with Ala 1, Trp 3, and Phe 29. The multiple electrostatic interactions have the thermal motion of Glu 14 reduced and the hydrogen bond between Glu 14 and Ala 1 remain at higher temperature. In the middle of the β-sheet, three hydrophobic residues, Val 4, Ile 11, and Leu 51 makes a cluster binding three strands of the β-sheet. This cluster aggregates more tightly with increasing temperature to stabilize the β-sheet and furthermore screens the hydrophobic core from the external thermal perturbation. These interactions are considered as important factors among the factors of the hyperthermostability which are not yet known perfectly.한국과학기술원 : 화학과