• 한국진공학회지
• /
• 제7권4호
• /
• pp.410-414
• /
• 1998

본 연구에서는 플라즈마 중합 반응의 기판 재질과 전극 위치에 대한 의존성을 규명 하기 위해서 Ar방전의 발광 분석을 행하였으며 제작된 박막의 가교성을 확인하기 위해서 전자빔 노광을 시켜보았다. 기판의 재질이 도체 및 절연체인 양자의 경우를 비교해 보면 전 자는 후자에 비해서 전체적으로 발광 스펙트럼의 피이크 강도가 크게 나타났으며, 준안정상 태에 대한 피이크와 이온에 대한 피이크를 검토한 결과, 기판이 절연물일 때는 전극의 위치 를 멀게 할수록 이온의 피이크 강도가 극단까지 떨어짐을 알 수 있었다. 제작된 중합스티렌 박막을 통하여 발광 스펙트럼의 변화에 따라서 막의 가교성 변화가 생기는 것을 알 수 있었 으며 이 막을 전자빔에 노광하였을 때, 기판이 절연물인 경우에는 패턴을 제작하는 것이 가 능하였다.

• 한국안전학회지
• /
• 제20권4호
• /
• pp.20-28
• /
• 2005

In this paper, the methodology for the reliability estimation of buried pipeline with longitudinal gouges and dent is presented and the limit state of buried pipeline is formulated by failure assessment diagram(FAD). The reliability of buried pipeline with defects has been estimated by using a theory of failure probability. The failure probability is calculated by using the FORM(first order reliability method) and Monte Carlo simulation. The results out of two procedures have been compared each other. It is found that the FORM and Monte Carlo simulation give similar results for varying boundary conditions and various random variables. Furthermore, it is also recognized that the failure probability increases with increasing of dent depth, gouge depth, gouge length, operating pressure, pipe outside radius and decreasing the wall thickness. And it is found that the analysis by using the failure assessment diagram gives highly conservative results than those by using the theory of failure probability.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.214-215
• /
• 2007

Etch rates and surface chemistry of phenol formaldehyde-based photoresist after short time $O_2\;and\;N_2O$ radio frequency (RF) plasma treatment depending on exposure time were investigated. It was found that the etch rate of photoresist sharply increased after discharge turn on and reached a limit with increase in plasma exposure time in both gases. X-ray photoelectron spectroscopy (XPS) analysis showed that the surface chemical structure become nearly constant after the treatment of 15 sec. Concentration of surface oxygen-containing groups after processing both in oxygen and in $N_2O$ plasmas is similar.

• 한국지진공학회논문집
• /
• 제23권1호
• /
• pp.19-29
• /
• 2019

Recent earthquakes in Korea caused some damages to stone pagodas and thereby awakened the importance of earthquake preparedness. Korean stone pagodas which have been built with very creative style of material use and construction method are worthy of world heritage. Each stone pagoda consists of three parts: top; body; and base. However each tower is uniquely defined by its own features, which makes it more difficult to generalize the seismic assessment method for stone pagodas. This study has focused on qualitative preliminary evaluation of stone pagodas that enables us to compare the relative seismic performance across major aspects among many various Korean pagodas. Specifically an analytical model for multi-block stone pagodas is to be proposed upon the investigation of structural characteristics of stone pagoda and their dynamic behavior. A strategy for seismic evaluation of heritage stone pagodas is to be established and major evaluation factors appropriate for the qualitative evaluation are identified. The evaluation factors for overall seismic resisting behavior of stone pagodas are selected based on the dynamic motions of a rigid block and its limit state. Numerical simulation analysis using discrete element method is performed to analyze the sensitivity of each factor to earthquake and discuss some effects on seismic performance.

• 한국지진공학회논문집
• /
• 제25권4호
• /
• pp.153-160
• /
• 2021

The connection of the steel structure serves to transmit external forces to the main components. The same is true for the behavior of modular systems composed mainly of steel or composite members. In this study, the joint performance of the composite and steel modules proposed was evaluated. The analytical models of the two joint types were constructed and were subjected to cyclic loading to assess the safety and the energy dissipation capacity of the joint types. The analysis results of the joints showed that the joints of the modular systems remain stable when the joint rotation reached the seismic performance limit state of the 0.02 rad required for steel intermediate moment frame. It was also observed that the joint of the composite modular system showed higher energy dissipation capacity compared with the steel modular system.

• Advances in aircraft and spacecraft science
• /
• 제9권3호
• /
• pp.263-278
• /
• 2022

The time-varying structural reliability of an aeroelastic launch vehicle subjected to stochastic parameters is investigated. The launch vehicle structure is under the combined action of several stochastic loads that include aerodynamics, thrust as well as internal combustion pressure. The launch vehicle's main body structural flexibility is modeled via the normal mode shapes of a free-free Euler beam, where the aerodynamic loadings on the vehicle are due to force on each incremental section of the vehicle. The rigid and elastic coupled nonlinear equations of motion are derived following the Lagrangian approach that results in a complete aeroelastic simulation for the prediction of the instantaneous launch vehicle rigid-body motion as well as the body elastic deformations. Reliability analysis has been performed based on two distinct limit state functions, defined as the maximum launch vehicle tip elastic deformation and also the maximum allowable stress occurring along the launch vehicle total length. In this fashion, the time-dependent reliability problem can be converted into an equivalent time-invariant reliability problem. Subsequently, the first-order reliability method, as well as the Monte Carlo simulation schemes, are employed to determine and verify the aeroelastic launch vehicle dynamic failure probability for a given flight time.

• International Journal of Knowledge Content Development & Technology
• /
• 제13권2호
• /
• pp.51-70
• /
• 2023

Nowadays, the growth rate of organisational politics in the library system is a cause of concern for library and information professionals. This has negatively impacted service delivery, most especially in public uni- versity libraries. This study examined the effect of organisational politics on job impetus among library personnel in selected public universities in South-west Nigeria. Three federal and three state universities were purposively selected such that one university was selected in each of the six states in South-west Nigeria. Total enumeration was used for all 187 library personnel in the six universities investigated. Using a descriptive survey of correlational type, a structured questionnaire was used to elicit information from respondents through survey monkey. Of 187 copies administered, 143, representing 76.5%, were retrieved and used for analysis. The results revealed a high level of organisational politics with low impetus. A strong inverse relationship was established between organisational politics and job impetus among library personnel in selected public universities in South-west Nigeria. Based on these, recommendations were made that Library personnel be encouraged to focus on their job specifications and limit organisational politics adhering to rules and regulations in the library and code of conduct for library staff.

• Nuclear Engineering and Technology
• /
• 제54권12호
• /
• pp.4759-4775
• /
• 2022

The RVACS is a versatile and robust safety system driven by two natural circulations: in-vessel coolant and ex-vessel air. To observe interaction between the two natural circulations, SINCRO-IT facility was designed with two different similarity laws simultaneously. Bo' based similarity law was employed for the in-vessel, while Ishii's similarity law for the ex-vessel excluding the radiation. Compared to the prototype, the sodium and air system, SINCRO-IT was designed with Wood's metal and air, having 1:4 of the length reduction, and 1.68:1 of the time scale ratio. For the steady state, RV temperature limit was violated at 0.8% of the decay heat, while the sodium boiling was predicted at 1.3%. It showed good accordance with the system code, TRACE. For an arbitrary re-criticality scenario with RVACS solitary operation, sodium boiling was predicted at 25,100 s after power increase from 1.0 to 2.0%, while the system code showed 30,300. Maximum temperature discrepancy between the experiments and system code was 4.2%. The design and methodology were validated by the system code TRACE in terms of the convection, and simultaneously, the system code was validated against the simulating experiments SINCRO-IT. The validated RVACS model could be imported to further accident analysis.

• 한국해안·해양공학회논문집
• /
• 제22권2호
• /
• pp.88-94
• /
• 2010

외부안정성을 다룬 동반논문과 차별화하여, 이 논문에서는 심층혼합처리지반에 설치된 안벽의 내부안정성에 대한 정량적 위험도 평가를 위한 신뢰성해석 방법을 제안하였다. 내부안정성 위험도 평가를 위해 개량지반의 단지압, 전단강도 그리고 무개량토의 압출 파괴모드에 대해 MVFOSM, FORM 그리고 MCS를 적용하여 안정성을 검토하고 비교하였다. 심층혼합처리지반상 안벽의 내부안정성에 대한 신뢰성해석 결과, 흙-시멘트 개량체 압축강도의 변동성과 분포형태가 파괴확률에 큰 영향을 미치는 것으로 나타났으며 다른 확률변수들의 영향은 상대적으로 미미했다. 그러므로 흙-시멘트 개량체의 현장 압축강도에 대한 통계적 특성을 합리적이고 정확하게 결정하는 것이 중요하다.

• 대한조선학회논문집
• /
• 제46권1호
• /
• pp.31-42
• /
• 2009

Common structural rule (CSR) doesn' t provide any other specific regulations for permanent means of access (PMA) platform structure in a cargo oil tank. The PMA platform is recommended to comply with scantling requirement of local support member. However, it leads to too conservative scantlings compared with actual loads imposed on the platform. This paper proposes a strength assessment procedure for the PMA structure based on a nonlinear ultimate strength. The ultimate strength is evaluated in a sufficiently conservative way. The first linear buckling mode is used as an initial imperfection shape and its magnitude is determined using the definitions of DNV PULS. Since the same imperfection mode as the failure mode of the ultimate limit state is assumed, it can accelerate the failure. Au ultimate strength capacity curve obtained from a series of nonlinear FE analysis is compared with actual stresses calculated by CSR cargo hold analysis.