• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.1
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• pp.95-100
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• 1993

The author observed a case of osteogenic sarcoma in a 11-year-old female with complaint of painful swelling on face in right side. The observed results were as follows: 1. Large hematoma was obsered, and patient complanited painfull swelling on c/c site. 2. Predisposing factor of osteogenic sarcoma was not clear, but patient had history of extraction before patient visiting infirmary of our dental collage. 3. Serologic findings were not specific, and serum alkaline level was normal. 4. Radiographic findings were as follows: ① Diffuse faint radiopacity in the lesion ② Bony destruction and increased radiopaciy in right antrum ③ Displacement of multiple teeth on involved area(i. e ;＃12, 15. 55, 16, 17, 18), ④, Increased periodontal space in singel tooth(＃13) ⑤Destruction of bony crypt on involved teeth(＃13, 14, 15, 17, 18) ⑥ Loss of lamina dura of three teeth in involved area(＃11, 12, 16) 5. Computed tomographic findings were as follows: ① Large calcific and hetergenous component mass in the Rt. maxillary sinus, and this mass extending to Rt. maxilla, alveolar bone, ethmoid sinus. ②, Soft tissue bulging into Rt. side nasal cavity and oral cavity. ③ Bone destruction of maxillary sinus wall and Rt. alveolar bone.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.201-203
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• 2002

In recent years there has been a growing interest in renewable energy systems due to the environmental problem and the economic benefits of fuel savings. Such systems are usually connected to the existing power grid for "fuel displacement" purpose as well as of earning some "capacity credit". Wind power generation system(WPGS) is one of the most useful energy resource using natural environment. So far, it was very difficult to simulate the dispersed generation system including WPGS using EMTP or EMTDC because the source of the dispersed generation system has a particular wind power characteristic equation. In this paper, a novel simulation method of WPGS has proposed and a new wind turbine component for EMTDC is also developed. The wind power characteristic equation of wind turbine is used in order to realize the WPGS in EMTDC simulation. And the real field data of weather conditions is interfaced to EMTDC using Fortran program interface method. Consequently the simulation of WPGS using field data is realized in this paper and shows acceptable results.

• The KSFM Journal of Fluid Machinery
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• v.8 no.6 s.33
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• pp.40-46
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• 2005

Because of design and manufacturing costs, it is important to predict an expected life of bellows with component stresses of bellows as its design factors and material characteristics. In this study, numerical analyses are carried out to elucidate the thermal and flow characteristics of the bellows-seal gate and globe valves for high temperature (max. $600^{\circ}C$) and for high pressure (max. $104 kgf/cm^2$) conditions. Using commercial codes, FLUENT, which uses FVM and SIMPLE algorithm, and ANSYS, which uses FEM, the pressure and temperature fields are graphically depicted. In addition, when bellows have an axial displacement, thermal stress affecting bellows life is studied. The pressure and temperature values obtained from the flow analyses are adopted as the boundary conditions for thermal stress analyses. As the result of this study, we got the reasonable coefficients for valve and thermal stress for bellows, compared with existing coefficients and calculated values.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1206-1215
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• 2005

The thermal stratification phenomena, frequently occurring in the component of nuclear power plant system such as pressurizer surge line, steam generator inlet nozzle, safety injection system (SIS), and chemical and volume control system (CVCS), can cause through-wall cracks, thermal fatigue, unexpected piping displacement and dislocation, and pipe support damage. The phenomenon is one of the unaccounted load in the design stage. However, the load have been found to be serious as nuclear power plant operation experience accumulates. In particular, the thermal stratification by the turbulent penetration or valve leak in the SIS and SCS pipe line can lead these safety systems to failure by the thermal fatigue. Therefore in this study an 1/10 scaledowned experimental rig had been designed and installed. And a series of experimental works had been executed to measure the temperature distribution (thermal stratification) in these systems by the turbulent penetration, valve leak, and heat transfer through valve. The results provide very valuable informations such as turbulent penetration depth, the possibility of thermal stratification by the heat transfer through valve, etc. Also the results are expected to be useful to understand the thermal stratification in these systems, establish the thermal strati­fication criteria and validate the calculation results by CFD Codes such as Fluent, Phenix, CFX.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1057-1063
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• 2012

A cycloid speed reducer is a type of the speed reducers. The cycloid speed reducer has a eccentric rotating motion and offset to avoid some problem of assembly, so it has a disadvantage for vibration. In this paper, a multi-body dynamic model is developed for a cycloid speed reducer and the dynamic behaviors of the reducer are investigated. The cycloid speed reducer consists of cycloidal plate gears, housing gear, input shaft, output pin and shaft, and eccentric bearings. Using a CAD program, each component of cycloid reducer is modeled based on the offset and multi-body simulations are performed using Recurdyn. As a result, the pin reaction force and the amplitude of bearing displacement are increased by the offset.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.4
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• pp.181-189
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• 2000

A weakly nonlinear mild-slope equation has been derived directly from the continuity equation with the aid of the Galerkin's method. The equation is combined with the momentum equations defined at the mean water level. A single component model has also been obtained in terms of the surface displacement. The linearized form is completely identical with the time-dependent mild-slope equation proposed by Smith and Sprinks(1975). For the verification purposes of the present nonlinear model, the degenerate forms were compared with Airy(1845)'s non-dispersive nonlinear wave equation, classical Boussinesq equation, andsecond¬order permanent Stokes waves. In this study, the present nonlinear wave equations are discretized by the approximate factorization techniques so that a tridiagonal matrix solver is used for each direction. Through the comparison with physical experiments, nonlinear wave model capacity was examined and the overall agreement was obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2015-2022
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• 2012

This paper is about the analysis and design of avionics equipment's housing and PCB(Printed Circuit Board) such as air data computer. Avionics equipment's structural design as well as electrical properties is very critical and should be proved from design phase by analysis method. First, analyze the static load and vibration requirement for the installed equipment, and then proved it satisfy with its requirement using the computational structural analysis. Commercial tools were used for computation and the rib design of housing was verified and the placement of electrical component was proposed using the PCB's local displacement information.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.90-93
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• 1999

We present a high frequency electromagnetic (EM) inversion scheme for detecting and characterizing a fracture using single-hole data. At high frequencies, say above tens of mega-hertz, since displacement currents cannot be ignored, electrical permittivity as well as electrical conductivity is to be considered together for analyzing the EM scattering data. In this paper, we have developed a three-step inversion scheme to map the fracture and to evaluate its electrical conductivity and permittivity. We performed EM profiling along the z-axis using three-component receivers for each source. The model was excited by a vertical magnetic dipole and the resistant magnetic fields were inverted using the non-linear least-squares method. Background resistivity and permittivity were easily obtained using vertical magnetic fields below 1 MHz and above 10 MHz, respectively. Both the vertical and dipping sheets were successfully mapped using the phase difference between 40 and 41 MHz. The electrical property of the sheet was well resolved using the information obtained in the previous two steps and secondary magnetic fields. Our study shows the potential of imaging the fracture in single-hole survey environment using the high frequency EM method.

• Transactions of the Society of Information Storage Systems
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• v.5 no.2
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• pp.76-81
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• 2009

Mobile devices have become an important part of daily life. This is especially true of laptop PCs, which are portable enough to be used almost anywhere. Laptop PCs, however, cannot be nomadic if each component is not robust enough to endure rugged laptop operating environment. Generally, external shock makes collision on head-disk interface and damage to read-write performance. To minimize the likelihood of failure, shock analysis must be incorporated into the design of hard disk drive in laptop. This research explores the structure modification of laptop HDD base, for improving shock performance using finite element analysis which considers the flexibility of whole HDD structure. FE model is verified by modal test and finely tuned. Then we obtained the transmitted acceleration of spindle and pivot and the relative displacement between disk and slider head as shock response. Based on shock simulation, the structural dynamics modification is performed and the primary design parameters are extracted.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.67-72
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• 2009

This paper covers finite element simulations to evaluate tube bending process of auto chassis component i.e. trailing-arm product. The rear of the auto chassis structure is primarily composed of CTBA and trailing-arm. When a car rolls into a corner, the trailing arm reacts to roll in the same degree as the car body. During the bending process of trailing arm the tube undergoes significant deformation. Thus forming defects such as excessive thinning and flattening of the tube will be formed in the outside of the tube. In this paper, we analyzed the effect of process parameters in rotary draw bending process and searched the optimized combination of process parameters using orthogonal arrays method to minimize the forming defects. In this process we analyzed several parameters which are displacement of pressure die, boosting force, initial position of mandrel bar, dimensions of mandrel in regarding to the thinning and flattening of the tube.