• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.167-167
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• 2006

Photo-/electroactive donor-acceptor (D-A) chromophores were synthesized and investigated for energy- and electron-transfer (ET/eT) properties, for which the chromophores are supramolecularly integrated by encapsulation with helical amylose, rendering the chromophores aggregation-free and rigidified along the helical axis and thus, a remarkably enhanced fluorescence intensity. Fluorescence quenching studies indicated that the helical encapsulation gives the ET/eT a clear D-A distance dependence unlike with the encapsulation-free counterparts, being reflected in their florescence decay profile. Another notable difference is that the helical supramolecule of the chromophores forms a perpendicularly oriented self-assembly. Transport behavior in the solid state will be also discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2695-2702
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• 2002

The elevator gear box with the helical gears needs to be developed instead of the one with the worm gears to improve the efficiency. In order to develop the gear box, the analytical tool to predict the helical gear noise is necessary to meet customer's noise requirement. Gear noise is related to the loaded transmission error. Therefore, the simulation program fer the loaded transmission error analysis of the helical gears is developed in this study. Using the developed program, the effects of tooth modification such as tip relief and the extent of tip relief are investigated. Finally, the procedures to determine the tip relief and the extent of tip relief are proposed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1643-1653
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• 1994

To facilitate the manufacturing of dull using CNC grinding machine, the simulation of helical groove machining with given wheel profile and setting condition is necessary. Considering the wheel as a collection of thin disks, the flute configuration is predicted in a cross section perpendicular to the axis and the grinding wheel profile is also predicted to machine the desired helical groove with given setting conditions. Two programs for these processes are developed. Using programs interactively, the helical groove machining process can be predicted more accurately. By clarifying the geometrical relation between the shape of cutting edge and the flute configuration in the cross section which is perpendicular to drill axis, it becomes possible to predict the necessary cross sectional shape of wheel for desired drill cutting edge shape. Some factors for the software are considered concerning prediction of accuracy and computing time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1534-1542
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• 1996

Gear vibration is caused by the mesh stiffness, gear accuracy, and assembling errors. For these reasons, helical gear has the azial, radial, and rotational vibrations. In this study, the mesh stiffness is calculated by considering the tooth bending, contact, and foundation deformations. Rotational vibration of helical gear with tooth error is modeled by the nonlidear equation of motion with single degree of freedom and is anlyzed numerically. Also, by a specially designed experimental set-up, the analysis are cross-checked and the vibration characteristics of helical gear are discussed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.45-50
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• 2007

In this paper, the FEM(Finite Element Method) has been applied to understand the geometrical characteristics and to analyze the stress of a helical gear. The helical gear is simulated and analyzed by adding many thin spur gear with helix angles and twist angles. Helical gears with different helix angle and face width have been studied. The results show that the root fillet stress is increased proportionally to helix angle and face width. Namely, as the face width increases, root fillet stress decreases, and as helix angle gets bigger, root fillet stress increases.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.245-248
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• 2006

The development of offshore structures have been increased spectacularly, especially in oil rig structures. This study concerns with the effects of heave motion of spar platform that attached the helical fin. There are three models, namely, cylinder, cylinder-truss and cylinder-cell with different geometrical dimensions are examined. Finally, the interaction between structure and fluid is closely considered. As the results, it can be seen that the existence of helical fin does not influence on surging but it affects a little on heaving of spar platform.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.253-254
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• 2006

In this investigation, the authors propose a novel method of Enveloping Helical gear generation by shaping operation and a math model to simulate its manufacturing process. The tooth geometry of the Enveloping Helical Gear is analytically determined by simulating the conjugate motion between the workpiece(Enveloping Helical gear) and cutting tool(shaper cutter) in the generation process. It is expected that such math modeling capability will give engineers an opportunity to correct manufacturing related issues in the design phase and thereby reduce the developing period.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.40-47
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• 1998

Drilling is an indispensable process in manufacturing of the die and mould and the other mechanical parts which needs high dimensional and surface accuracy. In this paper, a new type of drilling method was proposed in order to improve both processing efficiency and accuracy. Specifically, the helical motion using ball end mill tools, instead of normal drilling method, was applied to perform an effective hole machining. In this paper, an theoretical background of the new type of drilling method was established, and the feasibility of the proposed theory was proved by experiments, where proposed drilling process in the paper gave a different machining specification than general method did.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.139-142
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• 2009

As important mechanical elements, gears have been used widely in power transferring systems such as automobile transmission and there have been several researches trying to make gear parts with cold or warm forging in order to reduce cost and time required to gear manufacturing process. Although forging processes of spur and bevel gears have been developed as practical level owing to active previous researches in Korea, the manufacturing of helical gear has been still depended on traditional gear cutting processes such as hobbing, deburring and shaving. In order to manufacture helical gears with cold forging process, a research project supported by government has been conducted by Daegu university, KIMS and TAK and this paper deals with effects of back pressure forming technique to cold forging of helical gear as a fundamental research.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.208-212
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• 2001

DQM(differential quadrature method) is applied to computation of two dimensional elasticity problems in helical spring. Elastic shear stresses in an axially loaded helical spring having rectangular and square cross sections are calculated. The results are compared with those obtained using the method of successive approximations. The differential quadrature method gives good accuracy even when only a limited number of grid points is used.