• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.274-277
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• 2004

The most important mode of subcritical crack growth is primary water stress corrosion crack, which was the reported mechanism from the root cause analysis of the crack in the bimetallic welds. Stress corrosion crack growth evaluations was carried out for several flaw shapes of both axial and circumferential flaws, using the steady-state stresses including residual stresses. This evaluation considered the possibility of additional flaws in the primary loops of nuclear power plant, even though no such flaws have been identified by Ultrasonic Test. Consequently, Results show that the predicted flaw sizes will determine acceptability for continued service and maintenance.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1990년도 봄 학술발표회 논문집
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• pp.44-49
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• 1990

This study is a seismic analysia of absorber rod in KMRR Reactivity Control Mechanism. The model being studied i8 two coaxial tubes (control absorber rod and flow tube) immersed in the water and partially coupled (overlap) by water Hap. The hydrodynamic mass effects by the water in each surrounding conditions are considered in the model. The natural frequencies, stresses and displacements of the system due to Safe Shutdown Earthquake are computed in the cases of in-phase modes and out-of-phase modes of two coaxial tubes. The results show that maximum stresses are well below the allowable limit and maximum displacements at the ends of both tubes in out-of-phase modes are so huck that the tubes contact each other in the overlap zone.

• 한국산업융합학회 논문집
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• 제26권6_3호
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• pp.1341-1347
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• 2023

This study proposes to ensure the seismic stability of an existing switchboard for emergency diesel generator by applying mode analysis, static analysis and dynamic analysis. First, a three dimensional model for the swithboard was made with simplification for mode analysis. Next, The mode analysis for the finite element model of the existing switchboard was performed. The 1st natural frequency below 33 Hz, the seismic safety cutoff frequency, was calculated to be 21.943 Hz. Finally, based on the seismic stability theory, the von-Mises equivalent stresses derived by structural analysis and response spectrum analysis under the normal and faulted conditions were 74.179 MPa and 49.769 MPa, respectively. These are less than specified allowable stresses. So seismic stability was confirmed.

• Journal of the Korean Wood Science and Technology
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• 제39권1호
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• pp.1-7
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• 2011

최근 재종에 따른 등급별 품질기준 및 결점의 측정방법이 개정되었다. 외국 규격과의 호환성을 비롯하여 보다 현실에 맞고 적용하기 쉽게 개선하기 위해서는 개정에 따른 구조용제재의 구조성능에 대한 고찰이 필요하다. 본 연구에서는 국산 침엽수재 중 대표적으로 사용되는 낙엽송과 잣나무를 대상으로 구조용제재 규정 개정에 따른 휨강도 성능을 구명하였다. 개정된 등급구분규정은 구조재로 적합한 1, 2등급의 비율을 높인다는 측면과 1, 2 등급과 3등급 이하 등급과의 구분을 보다 명료하게 한다는 점에서 개정전의 등급구분에 비해 효과적인 것으로 나타났고, 각 등급별 5% 하한치와 허용응력은 전체적으로 감소하였다. 특히, 건축구조기준(KBC 2009)에서 제시하고 있는 기준허용응력은 실대재 실험값에 비해 더 낮은 값을 제시하고 있으므로 보다 정확한 허용응력의 사용과 효율적인 구조설계를 위해서는 기준허용응력의 개선 또한 필요할 것으로 판단된다.

• 한국생산제조학회지
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• 제7권6호
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• pp.12-18
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• 1998

The optimal design for stiffened laminate composite cylindrical shells under combined loads is studied by a nonlinear mathematical search algorithm. The optimal design is accomplished with the CONMIN. several types of buckling modes with maximum allowable stresses and strains are included as constraints in the optimal design process, such as general buckling, panel buckling with either stringers or rings smeared out, local skin buckling, local crippling of stiffener segments. Rectangular or T type stringers and rectangular rings are used for stiffened laminate composite cylindrical shells.

• 한국방재학회 논문집
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• 제7권1호통권24호
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• pp.29-38
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• 2007

틸팅차량의 안정성 확보를 위해 궤도부담력과 주행안정성 검토가 이루어졌으며, 틸팅차량이 궤도부담력과 주행안정성 검토에 의해 산정된 허용속도로 운행될 경우 레일이음매 하부 노반침하에 대한 연구가 수행되었다. 열차 주행시 레일이음매와 장대레일에 작용하는 충격량이 다르기 때문에 장대레일 하부 노반에 대한 안정성 검토가 추가적으로 필요하다. 본 연구에서는 장대레일에 대하여 노반의 침하량 및 지지력을 수치해석을 통해 검토하고 허용침하량 및 허용지지력과 비교하여 노반의 안정성을 검토하였으며 레일이음매와 장대레일 하부 노반의 침하량 및 지지력을 비교 분석하였다. 그 결과, 장대레일 및 레일이음부 하부 노반의 침하량은 허용침하량의 71.2% 및 88.8%, 응력은 허용지지력의 10.4% 및 12.1%로 나타났다.

• 드라이브 ㆍ 컨트롤
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• 제13권4호
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• pp.45-51
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• 2016

The power train of a hydro-mechanical, continuously variable transmission for forklifts makes use of hydro-static units, hydraulic multi-wet disc brakes & clutches, and complex helical & planetary gears. The complex helical & planetary gears are very important parts of the transmission because of a strength problem. In the present study, we calculated the specifications of the complex helical & planetary gear train, and analyzed the gear bending and compressive stresses of the gears. It is necessary to analyze the gear bending and compressive stresses thoroughly for optimal design of the complex helical & planetary gears with respect to cost and reliability. In this paper, we analyze the actual gear bending and compressive stresses of complex helical & planetary gears using the Lewes & Hertz equation, and we also verify the calculated specifications of the complex helical & planetary gears by evaluating the results of the data of allowable bending and compressive stress using the Stress vrs Number of Cycles curves of gears.

• 한국기계가공학회지
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• 제15권3호
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• pp.21-27
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• 2016

The static and dynamic structural integrity qualification was performed through the seismic analysis of a small-size Savonius-type vertical wind turbine at dead weight plus wind load and seismic loads. The ANSYS finite element program was used to develop the FEM model of the wind turbine and to accomplish static, modal, and dynamic frequency response analyses. The stress of the wind turbine structure for each wind load and dead weight was calculated and combined by taking the square root of the sum of the squares (SRSS) to obtain static stresses. Seismic response spectrum analysis was also carried out in the horizontal (X and Y) and vertical (Z) directions to determine the response stress distribution for the required response spectrum (RRS) at safe-shutdown earthquake with a 5% damping (SSE-5%) condition. The stress resulting from the seismic analysis in each of the three directions was combined with the SRSS to yield dynamic stresses. These static and dynamic stresses were summed by using the same SRSS. Finally, this total stress was compared with the allowable stress design, which was calculated based on the requirements of the KBC 2009, KS C IEC 61400-1, and KS C IEC 61400-2 codes.

• 대한기계학회논문집A
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• 제26권7호
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• pp.1376-1383
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• 2002

Seismic qualification of the Air Cleaning Units for nuclear power plant Ulchin 5&6 has been performed with the guideline of ASME Section III and IEEE 344 code. By using the structural and geometrical similarity analysis, the three models to be analyzed are condensed into a single model and, at the same time, the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz, which is the upper frequency limit of the seismic load, response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and electric stability of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As the all combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, the authors confirm the safety of the nuclear equipments Air Cleaning Units studied in this paper.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.498-498
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• 2001

Seismic qualification of the Main Control Boards for nuclear power plants has been performed with the guideline of AS ME Section III. US NRC Reg. Guide and IEEE 344 code. The analysis model of the Main Control Boards is consist of beam. shell and mass element by using the finite element method. and, at the same time. the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz. which is the upper frequency limit of the seismic load, the response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and functional integrity of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As all the combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, it concludes the Main Control Boards is dynamically qualified for seismic conditions. Although the authors had confirmed the structural and functional integrity of both Main Control Boards and all the component, in this paper only the seismic analysis of the Main Control Board is introduced.