• 한국기계가공학회지
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• 제20권3호
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• pp.60-67
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• 2021

Recently, research attention has been focused on vibration-free vehicles to transport small numbers of expensive electronic products. Vibration-free vehicles can be used to transport expensive test equipment or semiconductors, mainly produced in the domestic IT industry, and can serve as a readily available transportation system for short driving distances due to the increased efficiency on narrow national highways. This study was aimed at developing a Z-Spring to minimize the vibration by installing an air spring instead of the plate spring applied to conventional freight cars and to prevent the damage of the loaded cargo from the shock occurring during movement. The mechanical properties (elastic modulus, tensile strength, and shear strength) of carbon fiber (CF) and glass fiber (GF) prepreg were derived, and ANSYS ACP PrepPost analyses were performed. It was observed that in the case of hybrid composites, the total deformation and equivalent stress are higher than that of CFRP; however, in terms of the unit cost, the hybrid Z-Spring is more inexpensive and durable compared to the GF.

• 한국포장학회지
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• 제27권3호
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• pp.175-180
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• 2021

Although it has recently been regulated for use as an eco-friendly policy in Korea, the use of EPS (Expanded Polystyrene) cooling boxes, which are used as cold chain delivery insulation boxes for fresh agricultural and livestock products, is also increasing rapidly as e-commerce logistics such as delivery have increased rapidly due to COVID-19. Studies were conducted to optimize the EPS cooling container through internal air heat flow of CFD (Computational Fluid Dynamics) analysis and FEM (Finite Element Method) random vibration analysis using domestic PSD (Power Spectral Density) profile of the EPS cooling box to which the refrigerant is applied in this study. In the analysis of the internal air heat flow by the refrigerant in the EPS cooling box, the application of vertical protrusions inside was excellent in volume heat flow and internal air temperature distribution. In addition, as a result of random vibration analysis, the internal vertical protrusion gives the rigid effect of the cooling box, so that displacement and stress generation due to vibration during transport are smaller than that of a general cooling container without protrusion. By utilizing the resonance point (frequency) of the EPS cooling box derived by the Model analysis of ANSYS Software, it can be applied to the insulation and cushion packaging design of the EPS product line, which is widely used as insulation and cushion materials.

• 한국가스학회지
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• 제26권1호
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• pp.34-40
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• 2022

특정 고압가스 등을 사용하기 위해 배관과 안전장치 등이 일체로 구성된 가스 실린더 캐비닛은 화재 발생 시 고온의 열로 인한 급격한 압력상승으로 실린더 폭발 및 파편 비산 등의 위험성을 가지고 있다. 이러한 위험성은 용기 내부에 충전된 가스의 유출을 초래하여 중독, 질식 등의 2차 피해를 발생시킬 가능성이 크므로 내부 용기로 인한 피해를 줄이기 위해서는 가스 실린더 캐비닛의 내화성능 확보가 매우 중요하다. 국외의 경우 가스 실린더 캐비닛이 화염에 노출되는 상황에서 일정 시간동안 내부의 실린더를 보호할 수 있도록 미국 NFPA code, 유럽 EN-14470-2 등에서 가스 실린더 캐비닛 내화시험 기준을 규정하고 있다. 하지만 국내의 경우 내압성능과 기밀성능 기준만 명시되어 있고, 그 대상은 배관계로 한정되어 있으며 국외보다 가스 실린더 캐비닛의 내화성능을 위한 연구 및 규정이 미흡한 실정이다. 이에 본 연구에서는 국내 가스 실린더 캐비닛의 내화성능 기준 확립을 위해 유한요소해석 프로그램인 ANSYS를 이용하여 열해석을 수행함으로써 화재 발생 시 구조, 재질 측면에서의 최적 조건을 도출하고자 한다.

• 신재생에너지
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• 제18권2호
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• pp.73-81
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• 2022

This study was aimed at designing a condenser, as a component of the organic Rankine cycle system for ships. The condenser was manufactured through press molding to achieve a bent shape to enhance the heat transfer performance, considering the shape of the heat transfer plate used in a brazing plate heat exchanger. The heat transfer plate was made of copper-nickel alloy. The required heat transfer rate for the condenser was 110 kW, and the maximum number of layers was set as 25, considering the characteristics of high-temperature brazing. Computational fluid dynamics techniques were used to perform the thermal fluid analysis, based on the ANSYS CFX (v.18.1) commercial program. The heat transfer rate of the condenser was 4.96 kW for one layer (width and length of 0.224 and 0.7 m, respectively) of the heat transfer exchanger. The fin efficiency pertaining to the heat transfer plate was approximately 20%. The heat flow analysis for one layer of the heat exchanger plate indicated that the condenser with 25 layers of heat transfer plates could achieve a heat transfer rate of 110 kW.

• 한국공간구조학회논문집
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• 제22권3호
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• pp.33-40
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• 2022

Recently, cultural heritages in South Korea gain many interests of restoration and preservation from the government since many of that have been severely damaged during earthquakes. Many previous studies in both terms of experimental and analytical approaches have been done to examine structural behavior and decide appropriate methods of preservation. Being motivated by such researches, this research aims to investigate a religious stone pagoda dated back to the Goryeo Dynasty in Korea. The structure consists of a granite stone foundation and baked bricks, which resembles the shape of traditional pagodas. In order to examine the structural behavior of the pagoda, an analytical model is implemented using ANSYS, a comprehensive engineering simulation platform. For the time history analysis of the pagoda, several earthquake excitations are chosen and input to simulation modeling. Seismic response of the tower such as time domain, natural frequency, modal shapes and peak acceleration measured at each layer are presented and discussed. In addition, the amplification ratio of the tower is calculated from the accelerations of each layer to determine tower stability in accordance with Korean seismic design guide. The determination and evaluation of status and response of the brick tower by simulation analysis play an important role in the preservation of history as well as valuable architectural heritages in South Korea.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2743-2759
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• 2020

A detailed computational fluid dynamics (CFD) simulation analysis model was developed using ANSYS CFX 16.1 and analyzed to simulate the basic design and internal flow characteristics of a 180 MW small modular reactor (SMR) with a natural circulation flow system. To analyze the natural circulation phenomena without a pump for the initial flow generation inside the reactor, the flow characteristics were evaluated for each output assuming various initial powers relative to the critical condition. The eddy phenomenon and the flow imbalance phenomenon at each output were confirmed, and a flow leveling structure under the core was proposed for an optimization of the internal natural circulation flow. In the steady-state analysis, the temperature distribution and heat transfer speed at each position considering an increase in the output power of the core were calculated, and the conceptual design of the SMR had a sufficient thermal margin (31.4 K). A transient model with the output ranging from 0% to 100% was analyzed, and the obtained values were close to the T_hot and T_cold temperature difference value estimated in the conceptual design of the SMR. The K-factor was calculated from the flow analysis data of the CFX model and applied to an analysis model in RELAP5/MOD3.3, the optimal analysis system code for nuclear power plants. The CFX analysis results and RELAP analysis results were evaluated in terms of the internal flow characteristics per core output. The two codes, which model the same nuclear power plant, have different flow analysis schemes but can be used complementarily. In particular, it will be useful to carry out detailed studies of the timing of the steam generator intervention when an SMR is activated. The thermal and hydraulic characteristics of the models that applied porous media to the core & steam generators and the models that embodied the entire detail shape were compared and analyzed. Although there were differences in the ability to analyze detailed flow characteristics at some low powers, it was confirmed that there was no significant difference in the thermal hydraulic characteristics' analysis of the SMR system's conceptual design.

• Steel and Composite Structures
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• 제43권5호
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• pp.523-532
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• 2022

Turbocharger technology is one of the ways to survive in a competitive market that is facing increasing demand for fuel and improving the efficiency of vehicle engines. Turbocharging allows the engine to operate at close to its maximum power, thereby reducing the relative friction losses. One way to optimally understand the behavior of a turbocharger is to better understand the heat flow. In this paper, a 1.7 liter, 4 cylinder and 16 air valve gasoline engine turbocharger with compressible, viscous and 3D flow was investigated. The purpose of this paper is numerical investigation of the number of heat transfer in gasoline engines turbochargers under 3D flow and to examine the effect of different types of coatings on its performance; To do this, modeling of snail chamber and turbine blades in CATIA and simulation in ANSYS-FLUENT software have been used to compare the results of turbine with experimental results in both adiabatic and non-adiabatic (heat transfer) conditions. It should be noted that the turbine blades are modeled using multiple rotational coordinate methods. In the experimental section, we simulated our model without coating in two states of adiabatic and non-adiabatic. Then we matched our results with the experimental results to prove the validation of the model. Comparison of numerical and experimental results showed a difference of 8-10%, which indicates the accuracy and precision of numerical results. Also, in our studies, we concluded that the highest effective power of the turbocharged engine is achieved in the adiabatic state. We also used three types of SiO₂, Sic and Si₃N₄ ceramic coatings to investigate the effect of insulating coatings on turbine shells to prevent heat transfer. The results showed that SiO₂ has better results than the other two coatings due to its lower heat transfer coefficient.

• 한국기계가공학회지
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• 제20권11호
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• pp.67-73
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• 2021

Tanks are key weapons of ground combat that are equipped with powerful weapons and have strong protective bodies. One tank component, the engine clutch flange, is located in the part of the tank where the engine and transmission are installed, and it is a key part of the power transfer and shutoff. The engine clutch flange transmits high power to secure the mobility of the tank; thus, it must have high strength and hardness. In addition, high durability and safety must be ensured because tank operations must exclude concerns about damage. In this study, an engine clutch female flange for tanks made of SNCM439 was developed. The 2D design used AutoCAD programs, and the 3D shape design used CATIA programs. The structural analysis was conducted using ANSYS. The mesh grid has a tetrahedron shape and is created by adding a mid-side node. After the mechanical properties and constraints of SNCM439 were entered, the changes in the safety factor, total deformation, and Von-Mises stress were identified according to the increase in torque. Prototype processing was performed to verify the engine clutch female flange for the tank. To determine the productivity of the product, the cutting processing time was measured when processing the prototypes. Based on the results of measuring the cutting processing time, it is concluded that research is needed to improve productivity because MCT slot cutting processing is time consuming.

• Structural Engineering and Mechanics
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• 제82권1호
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• pp.1-16
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• 2022

This work elaborately investigates the influences of the guideway geometry parameters and track irregularity on the dynamic performances of the suspended monorail vehicle-guideway system (SMVGS). Firstly, a spatial dynamic analysis model of the SMVGS is established by adopting ANSYS parameter design language. Then, the dynamic interaction between a vehicle with maximum design load and guideway is investigated by numerical simulation and field tests, revealing the vehicle-guideway dynamic features. Subsequently, the influences of the guideway geometry parameters and track irregularity on the dynamic performances of the SMVGS are analyzed and discussed in detail, and the reasonable ranges of several key geometry parameters of the guideway are also obtained. Results show that the vehicle-guideway dynamic responses change nonlinearly with an increase of the guideway span, and especially the guideway dynamic performances can be effectively improved by reducing the guideway span; based on a comprehensive consideration of all performance indices of the SMVGS, the deflection-span ratio of the suspended monorail guideway is finally recommended to be 1/1054~1/868. The train load could cause a large bending deformation of the pier, which would intensify the car-body lateral displacement and decrease the vehicle riding comfort; to well limit the bending deformation of the pier, its cross-section dimension is suggested to be more than 0.8 m×0.8 m. The addition of the track irregularity amplitude has small influences on the displacements and stress of the guideway; however, it would significantly increase the vehicle-guideway vibrations and rate of load reduction of the driving tyre.

• Steel and Composite Structures
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• 제43권2호
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• pp.165-183
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• 2022

Most transportation departments have recognized and developed procedures to address the ever-increasing weights of trucks traveling on bridges in a service today. Transportation agencies also recognize the issues with overheight vehicles' collisions with bridges, but few stakeholders have definitive countermeasures. Bridges are becoming more vulnerable to collisions from overheight vehicles. The exact response under lateral impact force is difficult to predict. In this paper, nonlinear impact analysis shows that the degree of deformation recorded through the modeling of the unprotected vehicle-girder model provides realistic results compared to the observation from the US-61 bridge overheight vehicle impact. The predicted displacements are 0.229 m, 0.161 m, and 0.271 m in the girder bottom flange (lateral), bottom flange (vertical), and web (lateral) deformations, respectively, due to a truck traveling at 112.65 km/h. With such large deformations, the integrity of an impacted bridge becomes jeopardized, which in most cases requires closing the bridge for safety reasons and a need for rehabilitation. We proposed different sacrificial cushion systems to dissipate the energy of an overheight vehicle impact. The goal was to design and tune a suitable energy absorbing system that can protect the bridge and possibly reduce stresses in the overheight vehicle, minimizing the consequences of an impact. A material representing a Sorbothane high impact rubber was chosen and modeled in ANSYS. Out of three sacrificial schemes, a sandwich system is the best in protecting both the bridge and the overheight vehicle. The mitigation system reduced the lateral deflection in the bottom flange by 89%. The system decreased the stresses in the bridge girder and the top portion of the vehicle by 82% and 25%, respectively. The results reveal the capability of the proposed sacrificial system as an effective mitigation system.