• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.236-240
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• 2005

This paper deals with friction-induced vibration of disc brake system under constact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, The comparison of experimental and analytical results shows a good agreement and the analysis indicates that mode coupling due to friction force and geometric instability is responsible fur disc brake squeal. And the Front brake system reduced the squeal noise using design of experiment method(DOE). This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.987-991
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• 2005

The Aerial platform Truck is widely used for work in high place with the aerial platform. The most important thing is that worker's safety and worker must be able to work with trustworthiness so it needs to be verified its stiffness, deflection of boom, and dynamic condition concerned with a rollover accident. It should have an analytical exactitude because it is directly linked with the worker safety. In this point, we are trying to develop a proper CAE analysis model concerned with a rollover safety, bending stress and deflection for load. The Aerial platform Truck have a dynamic characteristics by load and moving of boom in the work field, so its static and dynamic strength analysis, structural mechanics are very important. Therefore, we evaluate the safety of each boom to calculating its stress, deflection. A computer simulation program is used widely for doing applying calculation of stiffness and structural mechanics, then finally trying to find a optimum design of the Aerial platform Truck.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.107-113
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• 2015

The goal of this paper is to investigate structural integrity factors of RMI(reflective metal insulation) to confirm the design requirements in nuclear power plant. Currently, a glass wool insulation is using now, but it will gradually be replaced with the reflective metal insulation maded by stainless steel plates. The main function of an insulation is to minimize a heat loss of vessel and pipes in RCS(reactor coolant system). It has to maintain structural a integrity in nuclear power plant life duration. In this study, the structural integrity analysis was carried out both multi-plate and outer shell plate by using a static analysis and experimental test. First, inner multi-plate has a self support structure for being air space. Because the effect of total static weight in multi-layer plate is low, a plate collapse possibility is not high. Considering optimum thin plate pressing process, it has to pre-check the basic physical properties. Second, the outer segment thickness and stiffener shape are verified by the numerical static analysis, and sample test for both type of panel and cylindrical pipe model.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.401-410
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• 2002

Concerns for energy conservation, environmental pollution, and the fact that organic wastes account for a major portion of our waste materials, have created the interest of biogas, which usually contains about 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and other gases, including ammonia, hydrogen sulfide, mercaptans and other noxious gases. Cyclone combustors are used for homing a wide range of fuels such as low calorific value gas, waste water, sludge. coal, etc. The 3-dimensional swirling flow, combustion and emission in a tangential inlet cyclone incinerator under different inlet conditions are simulated using a standard k-s turbulence model and ESCRS (Extended Simple Chemically-Reacting System) model. The commercial code Phoenics Ver.3.4 was used for the present work. The main parameters considered in this work are inlet velocity and air to fuel ratio. The results showed that the change of operating conditions had an influence on the shape and size of recirculation zones, mixture fraction and axial velocity which are important factors for combustion efficiency and emission behavior. The application of this kind of computer program seams to be promising as a potential tool for the optimum design of a cyclone combustor with low emission.

• Journal of electromagnetic engineering and science
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• v.7 no.3
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• pp.138-146
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• 2007

In this paper, a monopole antenna of conical-cylindrical compound shape is presented. The conventional circular conical monopole antenna is modified by placing a cylinder at the top of the inverted cone. The cylindrical portion is useful in the wide band impedance matching, in adjusting the antenna gain in the horizontal direction, and in reducing the cone diameter. The dependence of the antenna performance on various geometric parameters is investigated using a commercial electromagnetic simulation software, from which an optimum design of the antenna is derived. The diameter of the circular ground plane is minimized to 115 wavelength at the lowest operating frequency. The antenna proposed in this study shows a reflection coefficient less than -10 dB and a 1${\sim}$6 dBi gain over 3${\sim}$20 GHz frequencies. The antenna shows a circular-symmetric radiation pattern in the horizontal plane and a null-free pattern in the vertical direction over the whole operating frequency range.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.49-54
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• 2015

The fabrication of a focal length-correcting lens called the F-theta lens was performed by a 3D printer. The fabricated lenses were characterized by transmittance and reflectance measurements. The optical properties of the lens, such as scattering or transmittance efficiency, were analyzed with respect to the wavelength (red, green, and blue) and the surface roughness of the lens. There was almost no shape aberration on the focus location of 0 degrees, but elliptical focus shapes were found at 1 and 2 degrees of the laser incidence angle. The developed process is expected to be used for the quick fabrication of lenses with low costs and quick turn-out. By improving the surface roughness during postprocessing, the optical properties are expected to be comparable to commercial lens quality.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.101-106
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• 2012

The press bulging process is very useful and productive method to produce round-type mechanical components which have not been able to be manufactured because of limitation of the conventional press technology. The application of the press bulging process has expanded very quickly in the hydraulic and electronic industry and more recently it has been used to produce other mechanical parts such as the automobile and shipping parts. This expanding application also has brought some unsolved problems and leads many researchers to put their effort into the die design of the press bulging process. In this study, to obtain the optimum die shape for the press bulging process, various process parameters have been considered such as corner radius, bulging height, pressing length, and forming load, etc. The main interest of this paper is to verify the press bulging process which has more than 4.0 in height-length ratio. From this aspect, Finite Element analysis shows great ability to simulate the precise deformation process and gives us manufacturing database. Consideration of strain, stress, and strain-rate for the various cases has been also taken to keep the forming load within a particular range.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.547-556
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• 2002

Upright positioning of garlic cloves in mechanical planting has been considered as an essential process because pose of garlic affects not only initial budding and rooting of garlics but quality and yield. Due to the geometrical uniqueness and irregularity of garlic cloves in shape, manual planting operation has been conducted. The overall objective of this research was to determine design factors for designing a garlic clove planter The results are summarized as follows : 1. A vibrating-type clove-metering device was designed and tested. Effects of tilted angle of metering plate and magnitude of vibration on metering performance were investigated. The successful planting rates of the metering device were 96.7% for Hanji varieties. 2. Clove upright-positioning device, posture inducer was designed and tested. When the clearance between the hoppers was set at 4mm, the rates of upright positioning of the device were 92.2% for with Hanji varieties. 3. Optimum metering performance was observed at the plate tilted angle of 80。 with the posture type positioning device.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.6
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• pp.468-476
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• 2016

In this study, the conic winglet which is made by rotating wing tip airfoil by each 3 axis is applied to the dual type combined fan to reduce the wing tip leakage loss. Computational Fluid Dynamics is used to calculate the loss and optimum technique is used to get minimum loss. Optimization results shows that total pressure loss coefficient was reduced by 3.4 %, and optimization model was a bended shape at the end of wing forward to pressure side.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.540-545
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• 2008

An atrium has great potential in natural ventilation aided by buoyance effect. Architectural design of an atrium is very critical to maximize the effect. However, it is not easy of an atrium to have optimum shape for natural ventilation, from the aesthetic and economic point of view. Admitting this condition, we suggested a strategy to promote natural ventilation, which can be adopted only with small design change. At first, we installed BIPV on the top of an atrium to strengthen buoyancy effect, and combine forced ventilation by low pressure fan. To evaluate the performance of the measure, CFD simulation and Energy-Airflow analysis were achieved.