• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.561-566
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• 2011

In this paper, 1-D design of axial flow hydraulic turbine including runner blades, spiral casing with distributors(guide vanes and stay vane), and draft tube was conducted and then 3-D flow analysis was carried out using CFX-12.1. The results of 3 runners showed that with an increase in the number of blades, the flow rate and the power of the turbine system increased. On the other hand. the runner loss was not directly connected with the number of blades. As a result, proper blade number could be selected and more than 100kW small hydraulic turbine could be designed.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.2
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• pp.39-48
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• 2003

In the Semi-Solid Diecasters design, a Seni-Solid Diecasters experiment has usually been carried out before producing new casts. At the Semi-Solid Diecasting stages, the runner-gate part has been always repeatedly corrected, which leads to a tedious processing time and high processing cost. Much experience is essential in manual assessment and if the design is defective, much time and a great deal of efforts will be wasted in the modification of the die. In this study, a design system has been developed based on the design database In addition, a gate experiment for the gating system design has been tarried out to append the database. It is possible for engineers to make efficient gating system design of Semi-Solid Diecasting and it will result in the reduction of expenses and time to be required.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.4
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• pp.387-394
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• 2020

A parametric study of a 2.5 kW class propeller type micro hydraulic turbine was performed. In order to analyze the internal flow characteristics in the hydraulic turbine, three dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used and the hexahedral grid system was used to construct computational domain. To secure the reliability of the numerical analysis, the grid dependency test was performed using the grid convergence index method based on the Richardson extrapolation, and the grid dependency was removed when about 1.7 million nodes were used. For the parametric study, the axial distance at shroud span (L) between the inlet guide vane and the runner, and the inlet and outlet blade angles (β₁, β₂) of the runner were selected as the geometric parameters. The inlet and outlet angles of the runner were defined in the 3 spans from the hub to tip, and a total of 7 geometric parameters were investigated. It was confirmed that the outlet angles of the runner had the most sensitive effect on the power and efficiency of the micro hydraulic turbine.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.931-937
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• 2004

Simultaneous filling is a goal in plastic injection mold that has multi cavities. The moldings which have not been filled at the same time have undesired faults such as dimension inaccuracy, residual stress, law mechanical strength, etc. The best way to simultaneous fill is to be injected in a geometrically balanced runner system. In a general processing, however, in balanced runner system mold, filling imbalance would be observed in cavities. These phenomena result from molten polymer's characteristics and circumstances in balanced runner. In this study, the degree of filling imbalance (DFI) was defined for showing rate of filling imbalance in geometrically balanced injection mold that has 8 cavities. Before the main experiment, an injection molding simulation was conducted to know a pattern of filling imbalance with Moldflow software. There were somewhat differences between results of experiment and simulation about the filling imbalance. The reason for the difference was that the software have not concerned about a situation in a real flow channel. It was also investigated how the injection speed affected on filling imbalance in the experiment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.381-388
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• 2003

The paper presents our study of development for multi-cavity preform mold system which consists of hot runner system and valve gate. For this purpose, stretching blow molding process and preform injection process were simulated by Polyflow and Moldflow. Based on various results of the preform injection process analysis, process planning was established. The sectional thickness distribution of preform was optimized. Preform injection mold system was designed by these technical analysis data. Finally, 24-cavity preform mold system was successfully developed.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.248-252
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• 2014

In this paper, press and nut runner used in press-fit or tightening the bolts and nuts at assembling process of automobile parts companies continually demand accuracy and improved productivity. Simultaneous control of production systems through synchronization configuring of the combination multi press-fit system developed multi servo press system using the low-speed serial communication. As a result, the accuracy and the productivity is improved and product quality improvement could be achieved.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.78-82
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• 2008

Plastic gears are more and more widely used in many industrial machine elements. Plastic gear has higher properties such as light weight, wear resistance, and vibration absorbing ability than metallic gears. But, in case of using an inaccurate plastic gear, its tooth breakage happen and fatigue life is shortened due to increase of applying load and temperature rising on the tooth flank. Inaccuracy of plastic gears such as pitch circle roundness and tooth profile generates vibration and noise. In this study, an internal plastic gears which is molded by a new injection mold structure are developed. The new mold structure is called the HR3P(hot runner type 3plate mold) that has an improved runner system in order to have good filling balance. As a result from this study, an internal gear with very accurate roundness was developed by using design of experiment.

• Polymer(Korea)
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• v.32 no.6
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• pp.501-508
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• 2008

Small injection molded articles such as lens and mobile product parts are usually molded in multi-cavity mold. The problem occurring in multi-cavity molding is flow unbalance among the cavities. The flow unbalance affects the dimensions and physical properties of molded articles. First of all, the origin of flow unbalance is geometrical unbalance of the delivery system. However, even the geometry of the delivery system is well balanced, cavity unbalance occurs. This comes from the temperature distributions in the cross-section of runner. Temperature distribution depends upon injection speed because heat generation near runner wall is high at high injection speed. Among the operational conditions, injection speed is the most significant process variable affecting the filling unbalances in multi-cavity injection molding. In this study, experimental study of flow unbalance has been conducted for various injection speeds and materials. Also, the filling unbalances were compared with CAE results. The dimensions and weights of multi-cavity molded parts were examined. The results showed that the filling unbalances vary according to the injection speeds and resins. Subsequently, the unbalanced filling and pressure distribution in the multi-cavity affect the dimensions and physical states of molded parts.

• Steel and Composite Structures
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• v.32 no.6
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• pp.807-819
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• 2019

In recent earthquakes, the failure of ceiling systems has been one of the most widely reported damage and the major cause of functionality interruption in some buildings. In an effort to mitigate this damage, some scholars have studied a series of ceiling systems including plaster ceilings and mineral wool ceilings. But few studies have involved the backdrop metal ceiling used in some important constructions with higher rigidity and frequency such as the main control area of nuclear power plants. Therefore, in order to evaluate its seismic performance, a full-scale backdrop metal ceiling system, including steel runners and metal panels, was designed, fabricated and installed in a steel frame in this study. And the backdrop metal ceiling system with two perimeter attachments variants was tested: (i) the ends of the runners were connected with the angle steel to form an effective lateral constraint around the backdrop metal ceiling, (ii) the perimeter attachments of the main runner were retained, but the perimeter attachments of the cross runner were removed. In the experiments, different damage of the backdrop metal ceiling system was observed in detail under various earthquakes. Results showed that the backdrop metal ceiling had good integrity and excellent seismic performance. And the perimeter attachments of the cross runner had an adverse effect on the seismic performance of the backdrop metal ceiling under earthquakes. Meanwhile, a series of seismic construction measures and several suggestions that need to be paid attention were proposed in the text so that the backdrop metal ceiling can be better applied in the main control area of nuclear power plants and other important engineering projects.

• Design & Manufacturing
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• v.2 no.6
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• pp.33-37
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• 2008

Almost all injection molds have multi-cavity, which are designed with geometrically balanced runner system in order to made filling balance between cavity to cavity during injection molding. However, filling imbalance has been existed in the geometrically balanced runner system. In this study, we made an experiment and investigated that are filling balanced according to material. Also, in case of filling imbalance was occurred, we conducted experiments in order to find out difference of cavity pressure with cavity pressure sensor. When filling imbalance was occurred between cavity to cavity, we investigated the filling imbalance and pressure differences by computer-aided engineering(CAE).