• 항공우주기술
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• 제2권2호
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• pp.124-132
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• 2003

본 논문에서는 "KSR-III 복합재 가압탱크“에 대한 구조 설계/제작 과정을 기술하였다. 복합재 가압탱크는 라이너 위에 복합재가 덮어 씌워진 형태이다. 하중을 부담하지 않는 라이너는 AI 6061-0로 만들어 졌으며, 라이너는 헬륨가스 기밀만을 담당하였다. 복합재 탱크는 라이너 위에 T700/Epoxy로 와인딩 하였다. 알루미늄 라이너가 얇았기 때문에 다단계 경화 공정이 필라멘트 와인딩 기법에 적용되었다. 다단계 경화 공정은 라이너의 실린더가 원형 형상을 잃지 않게 하였다. 보스부의 체결력은 보스링에 의하여 카본섬유로 분산되었다. 또한 보스링은 보스부의 국부적 변형을 막았다.

• 항공우주기술
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• 제9권2호
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• pp.8-13
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• 2010

축추력의 효과적인 제어는 터보펌프의 작동 안정성을 확보하는 데 중요한 기술 중 하나이다. 현재 개발 중인 75톤급 로켓엔진용 연료펌프에 대한 축추력 측정을 상온의 물을 매질로 하여 실시하였다. 시험 결과, 연료펌프의 축추력은 펌프 베어링의 축방향 하중 조건을 만족하는 것으로 예상되었다. 또한 연료펌프의 축추력은 대체로 유량이 작을수록 커졌다. 그리고 플로팅 링 실과 임펠러 사이의 간극이 바뀌었을 때, 연료펌프의 축방향 하중과 후방 누설 유량이 변화하는 것을 확인하였다.

• 한국공작기계학회논문집
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• 제15권5호
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• pp.91-96
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• 2006

The friction and wear properties of ceramics are very important in the applications to engineering ceramic parts such as seal rings, pump parts, automobile meter parts, and so on. In this study, the effects of each other purity on the mechanical and tribological properties of purity zirconia ceramics were investigated. Also in order to determine the effects of sliding distance, sliding speed, contact load, friction coefficient, the amount of worn out material at a certain time, and the prepared composites were measured. Crystalline phases and microstructure were examined with XRD and SEM. The results show that we obtained the good properties of friction coefficient and wear resistance at the purity 99.5% of zirconia. than this of the purity 95% were great at the wear amount of worn out material.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.239-244
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• 2001

Hot hydrostatic extruder was developed. The main objective of the development is forming fine wire and tube. On account of effectiveness and high performance, the extruder was designed to have double action. Therefore the main cylinder and mandrel can be driven independently. To cope with severe condition of high temperature and pressure, wire-wound container equipped with heater was used. Sealing technique also is important in this process, so seal ring was made of super-elastic metal. Another key for successful forming is choice of proper pressure medium. Fine wire and tube produced by the extruder can be used in semiconductor industry and medicine.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.593-598
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• 2008

In the present study, degradation characteristics of pumps in nuclear power plants were investigated to provide the information of degradation mechanism and stressors. The failure records of pumps for the periods 2000 to 2006 on INPO(Institute of Nuclear Power Operations) EPIX(Equipment Performance and Information Exchange System) DB were reviewed. The 1,834 failure records reveal that the critical areas of pump failures are bearing, mechanical seal, gasket/o-ring, shaft, impeller, coupling and packing. Based on the failure rate of critical areas, the important degradation mechanism and stressors were determined. Additionally, the relationship between degradation mechanism and stressors such as wear was examined. Finally, the monitoring parameters related to degradation and stressors were discussed for the future development of degradation evaluation and prognosis technology of pumps.

• 공업화학
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• 제19권4호
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• pp.382-387
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• 2008

착체중합법을 이용하여 $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ 조성의 산화물을 합성하였으며, 합성된 분말은 압축 성형 후 $1080^{\circ}C$에서 소결하여 치밀한 페롭스카이트 분리막을 제조하였다. 밀봉 재료로 gold ring, Pyrex ring 및 Pyrex 분말을 사용하여 가스누출 실험을 수행하였다. $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ 분리막의 산소투과량 분석결과 온도가 증가함에 따라 산소투과량은 증가하였고, $900^{\circ}C$에서 $0.74mL/min{\cdot}cm^2$의 값을 나타내었다. $950^{\circ}C$에서 밀봉 재료에 따른 투과 특성 분석 결과, gold ring을 이용할 경우 높은 산소투과량을 보인 반면, Pyrex를 밀봉재로 사용할 경우 낮은 투과량을 보였다. 이는 Pyrex를 밀봉재로 이용할 경우 분리막 표면으로 유리가 침투하여 유효 산소투과면적을 감소시켰기 때문이며, 광화학 현미경 분석으로 Pyrex 유리의 확산 침투를 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1178-1184
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• 2008

In this study, techniques of ion implantation were used in order to improve the characteristics of metal materials such as the oxidation and wear resistant. In particular it is necessary to develope their oxidation and wear resistant that could be used in severe environmental conditions. There are mainly two elementary technologies including ion implantation and/or thin film coating. Ion implantation method was performed for surface modification. As a result, it was found that some ion implantations methods such as Nb, high-temperature Nb ion implantation and Nb+C combined implantation are somewhat effective for improving the oxidation resistance of TiAl alloy. Furthermore, the fluorine PBII treatment is more effective for improving the oxidation resistance of the TiAl alloy with three-dimensional shapes. The implantation of boron ion into thin film of TiN was also effective for improving the properties of materials like high temperature wear resistance. TiCrN film was applied to the actual seal ring for steam turbines, and it was observed that its sliding property showed a successfully good performance.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.565-578
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• 2016

A probabilistic based systems approach is addressed in this study for the reliability prediction of solid rocket motors (SRM). To achieve this goal, quantitative Failure Modes, Effects and Criticality Analysis (FMECA) approach is employed to determine the reliability of components, which are integrated into the Fault Tree Analysis (FTA) to obtain the system reliability. The quantitative FMECA is implemented by burden and capability approach when they are available. Otherwise, the semi-quantitative FMECA is taken using the failure rate handbook. Among the many failure modes in the SRM, four most important problems are chosen to illustrate the burden and capability approach, which are the rupture, fracture of the case, and leak due to the jointed bolt and O-ring seal failure. Four algorithms are employed to determine the failure probability of these problems, and compared with those by the Monte Carlo Simulation as well as the commercial code NESSUS for verification. Overall, the study offers a comprehensive treatment of the reliability practice for the SRM development, and may be useful across the wide range of propulsion systems in the aerospace community.

• 한국유체기계학회 논문집
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• 제15권6호
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• pp.46-50
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• 2012

A high-speed centrifugal pump requires more attention to the control of its axial thrust due to the high discharge pressure than a conventional industrial pump. Vanes employed toward the rear cavity of the impeller can be an effective device to control the axial thrust of the pump. The vanes disturb circumferential flow of the cavity and it can modify the axial force acting on the impeller. In this paper, three types of vanes are installed in the high-speed centrifugal pump for liquid rocket engines and the thrust of the pump is measured with an additional thrust measurement unit. According to the results, shapes of cavity vanes have effects on the axial thrust of the pump. As the height of vanes increases, the outlet pressure of the rear floating ring seal decreases which results in a decrease of the thrust. On the other hand, head of the pump is almost same regardless of cavity vanes. Also, the pressure drop of the bypass pipeline increases when vanes are removed.

• 제어로봇시스템학회논문지
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• 제22권11호
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• pp.888-894
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• 2016

This paper presents the kinematic and dynamic analysis of the robot arm for inspection and rescue operations. The inspection robot arm has Pitch-Pitch-Pitch-Yaw motion for an optimal and stable view of the camera installed at the end of the manipulator. The rescue operation robot arm has Yaw-Pitch-Pitch-Roll motion to handle heavy tools. Additionally, both robot arms are waterproof, as they use the triple-layer O-ring. Furthermore, the dynamic equation including the damping force due to the mechanical seal for waterproofness was derived by using the Newton-Euler method. A control system using the ARM processor was developed and introduced in this paper, and its performance was verified through experiments.