• Journal of Magnetics
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• v.4 no.3
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• pp.98-101
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• 1999

In this work we htave constructed an under water sonar transducer using Terfenol-D rod employing open magnetic circuit. Normally Sonar transducer using Terfenol-D was designed under closed magnetic flux return path, and permanent magnet for dc bias marnetic field, but high magnetic field should be applied to the transducer coil for high sound power and it brings temperature increase inside of the transducer. To improve this heat dissipation problem, we have designed an open magnetic circuit type transducer and we can get 200 dB (re. 1 Pa @ 1m) sound power for the input power of 650 VA.

• Journal of Magnetics
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• v.10 no.3
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• pp.77-79
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• 2005

In this work, we present a comprehensive and systematic approach for the derivation of the dc voltage generated by a magnetic multilayer undergoing ferromagnetic resonance, originally derived by Berger. Our alternative derivation applies especially in the limit of the spin diffusion length much longer than the carrier mean free path.

• Asia pacific journal of information systems
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• v.7 no.2
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• pp.225-266
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• 1997

A Causal Transition Model of the IT impact on organization is proposed. The model is based upon the premise that the IT impact is a multi-phase, multi-realm phenomenon, and that the IT impact in one organizational realm logically transpires to another realm, thus forming complex causal webs among them. Two exploratory research studies, the one qualitative and the other quantitative, were conductea to validate the model in a setting involving major structural reorganization of the organizations' IT function. The research results provide support for the general theory structure of the model. The findings include: ⅰ) the IT impact manifests on multiple organizational realms, with different degrees of strength, ⅱ) the impact on the realms follow a particular causal transition path among them, and ⅲ) the IT impact manifests on and through the information processing aspect of work. The results, however, indicate that people's perception of the IT impact is strongly mitigated by the IT relevance of work, and that the organization is affected as much by the structural arrangement surrounding and accompanying the IT as by the technology itself, suggesting that the IT impact is an organizational phenomenon as well as a technological phenomenon. The implications of the research results are discussed at the end.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.12 s.189
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• pp.38-45
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• 2006

In this work, optimal finish machining condition considering total time for mold or electrode manufacturing was investigated. First, manual finishing time according to the machining condition was analyzed for the work material. The effect of runout and phase shift of tool path on surface finish was also considered in those analyses. Secondly, optimal manual finishing processes were determined for various machining conditions. Finally, finish machining time and corresponding manual finishing time were taken into account for the estimation of the total time of manufacturing mold. Though small feed per tooth and pick feed reduced the manual finishing time, the finish machining time increased in such conditions. With a machining condition of feed per tooth of 0.2 mm and pick feed of 0.3 mm, the minimum total time of manufacturing mold was achieved in our machining condition.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.102-112
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• 2004

In this paper, we propose a human model for analysis for human work pattern or human fault, where a gantry crane simulator is used to survey the property of human operation. From the input and output of gantry crane response, we make a human operation model by using conventional ARX identification method. For identify the human model, we assume the eight inputs and two outputs. By using the input/output data, we estimate the parameters of ARX of the human system model. For verify the proposed method, we compared the real data with the modeled data, where three kinds of work trajectory path are used.

• ETRI Journal
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• v.28 no.1
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• pp.99-102
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• 2006

In this letter, we study the protection problem in wavelength division multiplexing (WDM) optical networks, and propose a novel dynamic heuristic algorithm called differentiated reliable segment protection (DRSP). Differing from previous work, DRSP can effectively avoid the trap problem and is able to find a feasible solution for each connection request. Therefore, DRSP outperforms the previous work. Simulation results have shown to be promising.

• International Journal of CAD/CAM
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• v.3 no.1_2
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• pp.1-12
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• 2003

When milling concave corners, cutter load increases momentarily and fluctuates severely due to concentration and uneven distribution of material stock. This abrupt change of cutter load produces undesirable machining results such as wavy machined surface and cutter breakage. An important factor for studying cutter load in 2.5D pocket milling is the instantaneous Radial Depth of Cut (RDC). However, previous work on RDC under different corner-cutting conditions is lacking. In this different corner shapes. In our work, we express RDC mathematically in terms of the instantaneous cutter engage angle which is defined as Cutter Swept Angle (CSA). An analytical approach for modeling CSA is explained. Finally, examples are shown to demonstrate that the proposed CSA modeling method can give an accurate prediction of cutter load pattern at cornering cut.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.325-332
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• 2000

The objective of this research work is to develop an autonomous levee-weeding robot. In this paper, pathway control system for the robot is developed and simulated. A prototype autonomous vehicle for levee weeding is also developed and used in the actual test. The results obtained in this research work is summarized as follows; 1) The simulated typical time history of lateral displacements and heading angle of the vehicle in straight run shows that the vehicle tendency is always to achieve the target path from any of its deviated position and heading angle. 2) The test run on an asphalt surface by the prototype crawler-type vehicle is in good agreement with the simulation results.

• Laser Solutions
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• v.5 no.3
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• pp.15-20
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• 2002

The principal obstacle to selection of a laser processing method in production is its relatively high equipment cost and the natural unwillingness of production supervision to try something new until it is thoroughly proven. The major objective of this work is focused on the combined features of gas tungsten arc and a low-power cold laser beam. In this work, the laser beam from a 7 watts carbon monoxide laser was combined with electrical discharges from a short-pulsed capacitive discharge GTA welding power supply. When the low power CO laser beam passes through a special composition shielding gas, the CO molecules in the gas absorbs the radiation, and ionizes through a process blown as non-equilibrium, vibration-vibration pumping. The resulting laser-induced plasma(LIP) was positioned between various configurations of electrodes. The high-voltage impulse applied to the electrodes forced rapid electrical breakdown between the electrodes. Electrical discharges between tungsten electrodes and aluminum sheet specimens followed the ionized path provided by LIP. The result was well-focused melted spots.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.598-603
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• 2000

In order to improve trial-and-error based conventional practices for optimizing forming processes, a direct design method to guide iterative design practices, called the ideal forming theory, has been previously developed. In the theory, material elements are required to deform following the minimum Plastic work Path. The theory can be used to determine the ideal initial blank shape needed to best achieve a specified final shape while resulting in optimum strain distributions. In this work, the direct design method based on the ideal forming theory was applied to design initial design shape for VCR deck chassis. Based on the solution of the ideal forming theory, FEM analysis was utilized to evaluate an optimum blank shape to be formed without tearing. Simulation results are in good agreement with experimental data. It was shown that the proposed sequential design procedure based on direct design method and FEM can be successfully applied to optimize the die design Procedure of sheet metal forming processes.