Structural characteristics have been analyzed for gear system in a commercial iron bending machine which is widely used at many building construction sites. This complicated gear system in the bending machine is fundamental power transfer unit from electrical motors, and it is composed of various configuration structure including various spur and helical gear assembly. Main structural characteristics of the gear system such as stress and deformation distributions are predicted with numerical simulation of FEM method for various operating conditions of torque and rotation speed. Results show that there is large deformation in lower region of driving gear, and high stress near those contact area which is greatly affected by motor torque. These results can be applied for the design improvement of efficient gear system in the iron bar bending machine.

This paper is about structural, and vibration analysis for the development of Index chucks Structural and vibration analyses were performed using the ANSYS Mechanical program to evaluate the Index chuck's structural stability and vibration characteristics. As a analysis result, when the maximum load of 500N was applied to the Index chuck, the safety factors were 2.06, 2.09, and 2.60, respectively, when the thickness was 5mm, and the outer diameters were 70mm, 90mm, and 120mm, respectively. Structurally safe results were obtained. In addition, under load conditions of 300 N or less, structural safety was confirmed if the thickness is 3mm or more.

경주 방폐물 처분시설의 1단계 시설로 건설된 지하 사일로 구조는 2014년에 10만 드럼 규모로 완공되어 현재 운영중에 있다. 지하 사일로 구조는 지름 25m, 높이 50m로써 방폐물을 저장하는 실린더부분과 돔 부분으로 구성되어 있으며, 돔부분은 운영터널과 연결 되는 하부 돔 부분과 상부 돔 부분으로 구분할 수 있다. 지하 사일로 구조의 벽체는 철근콘크리트 라이너이고, 두께는 약 1m이다. 본 논문에서는 지하 사일로 구조의 건설과정 및 운영과정의 단계별 유한요소해석을 수행하였다. SMAP-3D 프로그램을 사용하여 2차원 축대칭 유한요소해석을 수행하였다. 2차원 축대칭 유한요소모델의 신뢰성을 검토하고자 3차원 유한요소해석도 수행하였다. 본 논문 에서는 지하 사일로 구조의 구조거동을 분석하고 구조적 안전성을 검토결과를 제시하였다.

본 논문에서는 축하중과 폭발하중을 동시에 받는 철근콘크리트 부재의 구조 거동을 분석하였다. 기본적인 폭발하중을 받는 패널 실험 데이터, 축하중과 폭발하중을 받는 철근콘크리트 기둥 실험데이터를 이용하여 비선형 동적해석 모델링을 검증하였다. 축하중의 적용에 있어서 Autodyn은 동적해석만을 위한 프로그램이기 때문에 축하중과 같은 정적 하중에 대한 초기 응력 상태를 모사하는 해석 절차를 제시하였다. 축하중비 0%~70% 구간과 TNT 등가량에 의존한 환산거리 1.1~2.0에 해당하는 매개변수를 선정하여 총 80개의 비선형 동적 유한요소해석을 진행하였다. 축하중비와 환산거리의 변화를 통해 손상정도와 최대 변위 및 회전각으로 구조 거동을 비 교 분석한 결과로 원거리 폭발하중에서 축하중을 받는 기둥의 강성 증가로 최대 변위가 감소한다. 결과적으로 축하중비 10%~30%, 30%~50%, 50% 이상의 영역 3가지로 구조적 거동 분류가 가능함에 따라 내폭 설계 모델 개발에 활용될 수 있을 것으로 보인다.

Purpose: This study aimed to construct and test a hypothetical model to explain predictive factors affecting nursing students' satisfaction and self-confidence in simulation-based education based on the National League for Nursing Jeffries Simulation Theory. Methods: A cross-sectional study was conducted on 305 fourth-year nursing students with experience in simulation-based education enrolled at universities in Gangwon-do, Gyeongsangbuk-do, and Gyeonggi-do. Data were analyzed using SPSS 25.0 and AMOS 25.0. Results: The hypothetical model showed good fit with the empirical data: χ2/df 2.17, RMSEA=.01, RMR=.01, GFI=.95, AGFI=.91, NFI=.94, TLI=.95, CFI=.97, and PNFI=.68. Simulation design characteristics, teaching efficiency, and flow were found to affect satisfaction and self-confidence directly. A bootstrap test indicated that teaching efficiency and flow mediated the relationship between simulation design characteristics and satisfaction and self-confidence. Conclusion: Simulation educators should apply best practice that enhance teaching efficiency and flow through well-organized simulation designs, nursing students can attain satisfaction and self-confidence through simulation-based education.

The collapse of reinforced concrete (RC) frame buildings is mainly caused by the failure of columns. To prevent brittle failure of RC column, numerous studies have been conducted on the seismic performance of strengthened RC columns. Concrete jacketing method, which is one of the retrofitting method of RC members, can enhance strength and stiffness of original RC column with enlarged section and provide uniformly distributed lateral load capacity throughout the structure. The experimental studies have been conducted by many researchers to analyze seismic performance of seismic strengthened RC column. However, structures which have plan and vertical irregularities shows torsional behavior, and therefore it causes large deformation on RC column when subjected to seismic load. Thus, test results from concentric cyclic loading can be overestimated comparing to eccentric cyclic test results, In this paper, two kinds of eccentric loading pattern was suggested to analyze structural performance of RC columns, which are strengthened by concrete jacketing method with new details in jacketed section. Based on the results, it is concluded that specimens strengthened with new concrete jacketing method increased 830% of maximum load, 150% of maximum displacement and changed the failure modes of non-strengthened RC columns.

Transparent thin films of pure and nickel-doped ZrO2 are grown successfully by sol-gel dip-coating technique. The structural and optical properties according to the different annealing temperatures (300 oC, 400 oC and 500 oC) are investigated. Analysis of crystallographic properties through X-ray diffraction pattern reveals an increase in crystallite size due to increase in crystallinity with temperature. All fabricated thin films are highly-oriented along (101) planes, which enhances the increase in nickel doping. Scanning electron microscopy and energy dispersive spectroscopy are employed to confirm the homogeneity in surface morphology as well as the doping configuration of films. The extinction coefficient is found to be on the order of 102, showing the surface smoothness of deposited thin films. UV-visible spectroscopy reveals a decrease in the optical band gap with the increase in annealing temperature due to the increase in crystallite size. The variation in Urbach energy and defect density with doping and the change in annealing temperature are also studied.

Ti3C2Tx MXene, which is a representative of the two-dimensional MXene family, is attracting considerable attention due to its remarkable physicochemical and mechanical properties. Despite its strengths, however, it is known to be vulnerable to oxidation. Many researchers have investigated the oxidation behaviors of the material, but most researches were conducted at high temperatures above 500 oC in an oxidation-retarding environment. In this research, we studied changes in the structural and electrical properties of Ti3C2Tx MXene induced by low-temperature heat treatments in ambient conditions. It was found that a number of TiO2 particles were formed on the MXene surface when it was mildly heated to 200 oC. Heating the material to higher temperatures, up to 400 oC, the phase transformation of Ti3C2Tx MXene to TiO2 was accelerated, resulting in a TiO2/ Ti3C2Tx hybrid. Consequently, the metallic nature of pure Ti3C2Tx MXene was transformed to semiconductive behavior upon heat-treating at ≥ 200 oC. The results of this research clearly demonstrate that Ti3C2Tx MXene may be easily oxidized even at low temperatures once it is exposed to air.

Polyoxometalates (POMs) are nanoclusters composed of transition metals with high oxidation states. Owing to their redox properties and structural diversity, POMs have been applied to broad fields, such as catalysis, materials, and medicine. Among various fields of application, POMs play an important role in radiochemistry. POMs can form complexes with tri- and tetravalent lanthanides and actinides (radioactive elements), which may be good sequestrators or agents for separating nuclear wastes. Among the most prominent POM structures, Anderson-type POMs with a general formula of [Hy(XO6)M6O18]n− (y=0–6, n=2–8, M=addenda atom, X=heteroatom) represent one of the basic topological structures of the POM family. An important feature of Anderson type POMs is incorporating a large number of various heteroatoms with different size and oxidation states, which can lead to tune chemical properties. Interestingly, no example of Anderson type POMs with early transition metal ions in the heteroatom site has been reported to date. Herein, we discovered that the Anderson POM Na2K6Ti0.92W6.08O24·12H2O, which consists of pure inorganic framework built from a central Ti core supported by six WO6 inorganic scaffold, and the crystal structure was confirmed and refined using single-crystal X-ray diffraction (SC-XRD). In addition, structural characterizations, including, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Inductively coupled plasma-optical emission spectroscopy (ICP-OES) were performed.

Complexation of actinides and lanthanides with carboxylic organic ligands is known to facilitate migration of radionuclides from deep geological disposal systems of spent nuclear fuel. In order to examine the ligand-dependent structures of trivalent actinides and lanthanides, a series of Eu(III)-aliphatic dicarboxylate compounds, Eu2(oxalate)3(H2O)6, Eu2(malonate)3(H2O)6, and Eu2(succinate)3(H2O)2, were synthesized and characterized by using X-ray crystallography and time-resolved laser fluorescence spectroscopy. Powder X-ray diffraction results captured the transition of the coordination modes of aliphatic dicarboxylate ligands from side-on to end-on binding as the carbon chain length increases. This transition is illustrated in malonate bindings involving a combination of side-on and end-on modes. Strongly enhanced luminescence of these solid compounds, especially on the hypersensitive peak, indicates a low site symmetry of these solid compounds. Luminescence lifetimes of the compounds were measured to be increased, which is ascribed to the displacement of water molecules in the innersphere of Eu center upon bindings of the organic ligands. The numbers of remaining bound water molecules estimated from the increased luminescence lifetimes were in good agreement with crystal structures. The excitation-emission matrix spectra of these crystalline polymers suggest that oxalate ligands promote the sensitized luminescence of Eu(III), especially in the UV region. In the case of malonate and succinate ligands, charge transfer occurs in the opposite direction from Eu(III) to the ligands under UV excitation, resulting in weaker luminescence.

The structural stability of the recycled concrete disposal container was evaluated and compared the applicability of the current design standards for recycled concrete of nuclear power plant. The structural stability requirement for concrete disposal containers is 37.7 MPa or more. As a result of the compressive strength test on recycled concrete, 50% of coarse aggregates of recycled concrete was 42.1 MPa. In addition, it was found that the bending strength and shear strength of recycled reinforced concrete beam exceeded the current design standard. Therefore, it is judged that recycled concrete containing coarse aggregates can be sufficiently utilized. It was possible to ensure the structural stability of the concrete container without changing the design specifications and reinforcing bars when recycled concrete is applied.

Deep geological disposal with multiple barriers composed of engineered and natural barriers has been considered as the most suitable disposal method for high level nuclear wastes. In terms of the geological evaluation factors, brittle structures such as fractures and faults should be characterized around the repository site, because radionuclides transfer mainly with groundwater in the subsurface and groundwater flows through discontinuous brittle structures. The geological survey for the characterization of deep geological repository sites is widely conducted by narrowing the survey area from regional scale down to local scale, which could be divided into three steps: 1) using remote sense or geophysical survey, 2) trench and drill core logging including field survey based on the first step, 3) detailed geological survey in the tunnel. In this study, we analyzed the distribution of geological structures to derive the history of brittle deformation in and around the KURT (KAERI Underground Research Tunnel) site located in the KAERI (Korea Atomic Energy Research Institute). The bedrock of the KURT site is mainly consist of Jurassic two-mica granite, which is extensively intruded by andesitic dikes of Cretaceous with N-S to NE-SW strikes. The two-mica granite in the study area was deformed in a ductile deformation environment and has been overprinted by major geological structures such as faults, dikes, veins, and joints. From this study, we identified 8 brittle deformation events based on the cross-cutting relationship among the geological structures, which are obtained from the analyses in and around the KURT. In order to evaluate the reactivation and fluid flow potential of brittle structures, it is essential to determine the characteristics and ages of the brittle structures and the composed rocks around the site.

철근 콘크리트 하수관거는 경제적 장점과 내구성으로 인해 많이 사용되고 있다. 오랜 공용시간 이후 하수관거는 하 수의 산화물과 공용하중에 의해 열화가 진행된다. 본 논문은 초고강도 콘크리트로 갱생한 열화된 콘크리트 하수관거의 구조적 성능에 대해 연구하였다. 실험변수는 초고강도 콘크리트 관거 상부슬래브와 벽체의 두께의 조합으로 구성하였다. 네가지 종류의 초고강도 콘크리트 관거가 극한하중을 받을 때까지 내하력을 파악하기 위해 실험을 진행하였다. 보통 강도 콘크리트에 비해 상 대적으로 작은 두께의 초고강도 콘크리트 관거는 열화된 내부 부분을 치핑하고 갱생함으로써 단면의 손실을 최소화할 수 있다. 실험결과에 의하면 열화된 콘크리트 관거를 갱생하는데 적용된 새로운 얇은 두께의 초고강도 콘크리트 구조물이 재하하중을 만 족하고 실제 공학적 적용에 용이성을 있음을 나타내고 있다.