• Corrosion Science and Technology
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• 제21권6호
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• pp.495-502
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• 2022

Anodization is a representative electrochemical surface treatment method that can improve both heat resistance and corrosion resistance by forming an anodization film on the surface of the aluminum. However, these properties can be changed after an additional heat treatment process. In this study, Al 6061 was subjected to an anodization process at 60 V for 1 hour, 5 hours, or 9 hours. An additional heat treatment process was performed at 500 ℃ for 30 minutes. Field emission scanning electron microscopy (FE-SEM) analysis revealed that the thickness of the anodized film was increased in proportion to the anodization time. Both pore size and pore diameter of the anodized film was also increased after anodization. After an additional heat treatment process, there were no significant changes in the thickness, pore size, or pore diameter of the anodized film. Heat resistance was confirmed through thermal analysis and chemical resistance was evaluated with a potentiodynamic polarization test.

• 대한기계학회논문집A
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• 제29권1호
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• pp.107-114
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• 2005

In order to analyze the elastic-plastic fracture behavior of a structure, the fracture resistance curve of the material should be known first. The standard CT specimen was used to obtain the fracture resistance curves of a piping system. However, it is known that the fracture resistance curve by the standard CT specimen is very conservative to evaluate the integrity of a structure. Also the fracture resistance curve is effected by the specimen geometry and the dimensions because of the constraint effect. The objective of this paper is to be certain the conservativeness of the fracture resistance curve by the standard CT specimen and to provide an additional safety margin. For these, the fracture tests using a real pipe specimen and the standard CT specimen test were performed. A 4-point bending jig was manufactured for the pipe test and the direct current potential drop method was used to measure the crack extension and the length for the pipe test. Also finite element analyses were performed with a CT specimen and a pipe in order to prove the additional safety margin. From the result of tests and analyses of the pipe and the standard CT specimen, it was observed that the fracture analysis with the standard CT specimen is conservative and the additional safety margin was proved.

• Tuberculosis and Respiratory Diseases
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• 제66권3호
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• pp.198-204
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• 2009

연구배경: 다제내성결핵 치료에서 감수성으로 증명된 1차 항결핵제는 가장 항결핵효과가 큰 약제로 알려져 있다. 본 연구는 다제내성결핵 환자에서 표준 1차 항결핵제사용 후 1차 항결핵제에 대한 추가 내성 획득의 빈도와 그 위험 인자를 알아보고자 시행되었다. 방 법: 2004년 1월에서 2008년 5월까지 국립마산결핵병원에서 약제감수성 검사가 보고되기 전 표준 1차 항결핵제로 치료받은 다제내성결핵 환자 중에서 1차 항결핵제 치료 전과 1차 항결핵제 치료 후의 연속된 두 시점의 약제 감수성 검사 결과가 모두 있는 환자를 대상으로 하여 의무기록을 후향적으로 검토하였다. 결 과: 표준 1차 항결핵제로 치료 받은 41명 중 14명 (34.1%)에서 ethambutol (EMB) 혹은 pyrazinamide (PZA)에 대한 추가 내성이 획득되었다. 치료 전 isoniazid (INH), rifampicin (RFP)에만 내성을 보였던 11명 중 3명(27.3%)에선 EMB와 PZA에 동시 내성, 3명(27.3%)에선 PZA에 추가 내성이 획득되었다. INH, RFP, EMB에 내성을 보인 18명 중 6명(33.3%)에서 PZA에, INH, RFP, PZA에 내성을 보인 6명 중 2명(33.3%)에서 EMB에 추가 내성이 획득되었다. 대상 환자 중 10명(24.4%)에서 1차 항결핵제 치료 전 내성이었던 약제가 치료 후 감수성으로 전환되었다. 추가 내성획득과 연관된 통계학적으로 유의한 위험인자를 발견할 수 없었다. 결 론: 우리나라의 다제내성결핵 치료에서 1차 항결핵제는 추가 획득 내성의 위험을 고려하여 주의 깊게 사용해야 할 것으로 사료된다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.223-228
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• 1999

We have investigated the microwave properties of a high-T$_c$. superconducting Josephson junction by Shapiro step measurements. A Josephson junction was fabricated on the bicrystal MgO substrate using pulsed laser deposition method. We have measured Shapiro steps in the I-V characteristics under the irradiation of 1.36 cm wavelength up to 45 K and found inclined current steps above 50 K. In order to understand these results, we introduced an additional resistance connected in series to RSJ model. Using this modified RSJ model, we could explain the inclined current steps as a result of superposition of the junction and an additional resistance above certain temperatures. Also, we presented the received power of the Josephson junction above 50 K.

• 한국농공학회논문집
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• 제61권3호
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• pp.23-30
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• 2019

In this study, we evaluated the applicability of proper embedded depth of fillings by examining the uplift resistance using spiral foundation and top base foundation. As a result of the model test, the maximum uplift resistance increased with the embedded depth. The maximum uplift resistance of each region was found to be 50cm depth. The spiral foundation was 335.14N of Sancheong, 312.32N of Seongju, 403.94N of Wanju, and the top base foundation was 745.06N of Sancheong, 1028.82N of Seongju and 950.76N of Wanju. The yield point after the elastic section in the stress-displacement graph of the top base foundation was calculated as the maximum uplift resistance. For this reason, farmers do not actually use top bases foundation. Therefore, it was considered that the additional load increase due to slip connector will not occur. Model test results show that the maximum uplift resistance increases with the purlinss installed under the ground. Therefore, additional comparative studies through purlins installation will be needed.

• 한국항해항만학회지
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• 제38권5호
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• pp.463-470
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• 2014

본 논문에서는 선박의 예인에 필요한 예인력의 계산과 이를 검증하기 위한 실험 결과에 대해 언급하고 있다. 먼저 예인력의 계산에 있어서는 선박의 마찰저항, 풍압저항, 조파저항을 고려하였다. 아울러 프로펠러가 고착된 상태를 가정하여 프로펠러 저항을 계산하였다. 이와 더불어 예인 시 사용되는 예인삭에 걸리는 부가저항을 노드분석법을 적용하여 계산하였고, 선체 저항과 예인삭에서의 부가저항을 합하여 최종적인 예인저항을 도출하였다. 계산된 결과값의 유효성을 검증하기 위하여 목포해양대학교 실습선 새유달호를 활용하여 해상에서 예인실험을 수행하였고 이론적인 계산 결과와 실험 결과에 대한 비교를 행하였다. 소요 예인력의 이론적인 계산에서 주요한 요소는 예인속력임을 알 수 있었고, 예인속력의 증가에 따라 프로펠러 고착 저항이 저항의 주요한 부분을 차지하는 것을 확인하였다. 실제 실험을 통해서는 선박의 요잉에 의한 저항 증가분을 고려하는 것이 필요하다는 것을 알 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.205-206
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• 2021

A comparative analysis of wear resistance and shock resistance tests shows that wear resistance is up to 6 times and at least 2 times higher wear resistance than current products, even considering the limited number of turns due to too much rotation. In the case of shock resistance, there was no problem except 7.5T, but this is only a result of KS test method, so it is deemed that additional fall impact tests by various objects in daily life are needed for practical comparison.

• 한국해양공학회지
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• 제13권1호통권31호
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• pp.18-22
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• 1999

One of the problem areas in designing a barge is its resistance and corese stability when it is towed by a tugboat. In this paper, as a part of design of a incinerating vessel, the results of some experimental studies on the effect of various kinds of anti-yawing skegs to the course keeping stability and on the additional resistance caused by them were summarized.

• 센서학회지
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• 제26권6호
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• pp.397-401
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• 2017

A DC resistance type humidity sensor using conductive carbon ink was fabricated and its performance was evaluated. The humidity sensor was fabricated using a screen printing technique and have a structure that does not require additional metal electrodes to measure resistance change. To evaluate the performance of the humidity sensor, we measured the DC resistance change under various relative humidity levels. The fabricated humidity sensor showed a resistance change of about $2.5{\sim}50k{\Omega}$ in 11 ~ 95% RH environment. It also shows a linear relationship in the relative humidity versus log DC resistance graph. In comparison with commercial humidity sensor under real environment, it can be confirmed that the resistance of the humidity sensor changes to almost the same level as the measured humidity. These results show that the resistance type humidity sensor can be operated stably in actual environment.

• 수산해양기술연구
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• 제59권4호
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• pp.344-353
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• 2023

In the actual sea, the additional resistance due to external force such as wind, current and wave is accompanied, and the required power is added in response to these resistance. Especially when the ship is sailing at low speed, the effects of wind and current have a great impact on the safe control of the ship. Likewise, it is thought that the effects of wind and current have a great impact on the trawl ship control since the towing speed of a bottom trawl ship is a low speed of 3 to 4 knots. If the reduce of ship speed and the increase of engine power due to the influence of wind and current can be identified, the safe towing power can be calculated based on a given engine output. Thus, the appropriate size of a fishing gear can be determined. In this study, a total of 20 trawl operations were conducted for seasonal maritime research in the same research area according to the operation mode of propeller. Based on navigation data, trawl fishing data, and engine performance data acquired during the towing fishing gear, and data of ship speed, hull resistance, fishing gear resistance, wind force and current force according to an incidence angle were estimated. The overall power for these loads was calculated and compared with the measured engine power, and the effects of wind force and current force on the engine power were investigated.