• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.263-272
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• 2018

Purpose: The load on the planet gear of a planetary gear set is uniformly distributed. However, manufacturing and assembly errors cause uneven load sharing in the planetary gear set. To solve this problem, most studies have suggested applying a floating sun gear to the planetary gear set. However, the effect of the floating ring gear and floating carrier has not been extensively studied. This study aimed to investigate the effect of the floating ring gear. Methods: Two models were developed; one was the fixed ring gear model, and the other was the floating ring gear model. In the fixed ring gear model, the clearance between the ring gear and the housing was $0{\mu}m$, and in the floating ring gear model, the clearance was from $10{\mu}m$ to $100{\mu}m$. The load sharing of the planetary gear set was evaluated by the load sharing factor. Results: Our study showed that with increase in clearance, the load sharing factor of the planetary gear set approached unity. In addition, when the clearance increased above a certain level by which a fully floating ring gear was achieved, the load sharing factor was not affected by the clearance. Conclusions: This indicates that the fully floating ring gear increased the power density of the planetary gearbox by uniformly dividing the load of the planetary gear set. For this reason, the size of the gearbox could be decreased by using a fully floating ring gear.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.2
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• pp.41-48
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• 2000

An experimental study is made to improve the efficiency of floating breakwaters. Wave transmission coefficients highly depend on the drafts of the floating breakwaters but not on the mooting chain weights. Array of two breakwaters can improve the efficiency of the floating breakwaters. Proper draft combination of the fore and the aft bodies may improve the performance of the floating breakwaters lot various wave periods.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.137-152
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• 2016

This paper studied the dynamic response of a new gasbag-type floating bridge under the effect of a moving load. The arbitrary Lagrangian-Eulerian (ALE) method was used to simulate the movement of seawater and air, and the penalty-based method was used to study the coupling between gasbags and fluid. A three-dimensional finite element model of the floating bridge was established, and the numerical model was verified by comparing with the experimental results. In order to prevent resonance, the natural frequencies and flexural mode shapes were analyzed. Based on the initial state analysis, the dynamic responses of the floating bridge subjected to different moving loads were investigated. Vertical displacements and radial deformations of gasbags under different loads were compared, and principal stress distributions of gasbags were researched while driving. The hinge forces between adjacent modules were calculated to ensure the connection strength. Besides, the floating bridge under wave impacting was analyzed. Those results can provide references for the analysis and design of this new floating bridge.

• Tribology and Lubricants
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• v.19 no.6
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• pp.349-356
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• 2003

A damper floating ring seal with round hole pattern surfaces is suggested for better leakage control. The flat plate test of the round hole pattern surfaces has been performed to yield an empirical friction factor model. The exact predictions of the lock­up position of the damper floating ring, the leakage performance, and the rotordynamic coefficients of the seal are necessary to evaluate the rotordynamic performance of the turbo pump unit. The governing equations including the empirical friction factor model for round hole pattern surfaces are solved by the Fast Fourier Transform method. The lock­up position, leakage flow rate, and rotordynamic coefficients are evaluated according to the geometric parameters of the damper floating ring seal. Theoretical results show that the damper floating ring seals yield less leakage and better rotordynamic stability than the floating ring seal with a smooth surface.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.11
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• pp.47-55
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• 1997

In general, processing flow of the conventional floating-point multiplication consists of either multiplication, addition, normalization, and rounding stage of the conventional floating-point multiplier requries a high speed adder for increment, increasing the overall execution time and occuping a large amount of chip area. A floating-point multiplier performing addition and IEEE rounding in parallel is designed by using the carry select addder used in the addition stage and optimizing the operational flow based on the charcteristics of floating point multiplication operation. A hardware model for the floating point multiplier is proposed and its operational model is algebraically analyzed in this paper. The proposed floating point multiplier does not require and additional execution time nor any high spped adder for rounding operation. Thus, performance improvement and cost-effective design can be achieved by this suggested approach.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.83-88
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• 2013

The purpose of this study is to develop the algorithm for dynamic interaction analysis of submerged floating tunnel and vehicles. The dynamic behavior characteristic of submerged floating tunnel is certainly different with general structures, because the submerged floating tunnel is floating in the middle of water, and subjected to constant buoyance. Therefore the analyses in various aspects should be carried out to secure structural stability and practicality of structures. To conduct the dynamic interaction analysis, the structure is modeled by commercial FEM program ABAQUS to investigate modal characteristic. Also the added mass concept is applied to represent the inertial force by a fluid, and then dynamic interaction analyses are conducted with superposition method when the KTX is moving along the submerged floating tunnel. And the time histories are presented for vertical and lateral displacement at the center of the tunnel.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1006-1012
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• 2003

Recently, floating offshore structure is studied as one of the effective utilization of the ocean space. And floating structure are now being considered for various applications such as floating airports, offshore cities and so on. The motion analysis of the fishing spot of floating offshore structure as it receives regular wave is studied. The finite element method is used in the analysis of structural section of this structure. And the analysis is carried out using the boundary element method in the fluid division. In order to know the characteristics of the motion of the floating fishing spot structures, effects of wavelength, water depth, and wave direction on dynamic response of the floating structure are studied by use of numerical calculation.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.2
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• pp.90-95
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• 2017

In case of working for the construction of blocks of any ship in a floating dry dock, there may exist deflection in the pontoon deck of the floating dock due to the ballast loading and the self weight of the ship and the floating dock. This paper is on the development of the measuring system and the GUI program to show the real time variation of the deflections at even-spaced positions by several pressure gages and the calculated inclination of the floating dock. The measured and calculated data produced by this developed system could be used to prepare the protection plan on site like ballast adjustment to ensure the safety of working during the floating dock operation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.67-72
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• 2011

In this study we investigate the background of UPS output transformer(${\Delta}-Y$) operation on neutral ungrounded system, and perform field experiment of neutral floating-phenomenon for the inter-locked securing of electric facilities and improvement of neutral floating-phenomenon. Experiment results show that a floating-phenomenon occurs when four-pole input-breaker trip and the neutral to earth voltage occurring concurrently is identified as phantom voltage. And the measures for the transient overvoltage that can occur in floating-state also are investigated. As a result, the risk elements of neutral ungrounded method as well as neutral floating-phenomenon are removed by installation of separate solidly-grounded transformer and switching four-pole input-breaker to three-pole input breaker.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.9
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• pp.523-526
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• 2016

This paper was researched about 1,200 V level floating island IGBT (insulated gate bipolar transistor). Presently, 1,200 V level IGBT is used in Inverter for distributed power generation. We analyzed and compared electrical charateristics of the proposed floating island IGBT and conventional IGBT. For analyzing and comparison, we used T-CAD tool and simulated the electrical charateristics of the devices. And we extracted optimal design and process parameter of the devices. As a result of experiments, we obtained 1,456 V and 1,459 V of breakdown voltages, respectively. And we obatined 4.06 V and 4.09 V of threshold voltages, respectively. On the other hand, on-state voltage drop of floating island IGBT was 3.75 V. but on-state vlotage drop of the conventional IGBT was 4.65 V. Therefore, we almost knew that the proposed floating island IGBT was superior than the conventional IGBT in terms of power dissipation.