• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.12
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• pp.874-882
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• 2007

The effects of a guide fin blade on the flow characteristics in a ventilating axial fan were investigated experimentally. The guide fins were setup onto the pressure surface of the blade, and their effects on the flowrate were evaluated. Two types of the guide fin blade were designed. One is the stem fin blade, and the other is the radial fin blade. The stem fin is designed normal to the circumference of a circle, and the radial fin is designed along the circumference of a circle. The results from the guide fin blade fans are compared with that of the blade without guide fins. The position and the geometry of the radial fin setting up on the blade have an effect on the increase of flowrate with the minor sacrifice of rotational speed of the blades. The radial fin positioning at 0.84 times blade diameter shows highest performance in the flowrate. The increase of the blade weight resulting from applying the guide fins shows minor effect on the variation of rotational speed of the blades.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.229-235
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• 2010

Optimum values of fin performance and dimensions for an annular fin with a rectangular profile and a pipe with variable inner radius are determined by using a variable separation method. The range of ambient convection characteristic number that results in optimum heat loss is listed. The optimum heat loss, corresponding optimum fin effectiveness, fin length, and fin height are presented as a function of the inner radius of the pipe, inner fluid convection characteristic number, fin volume, and ambient convection characteristic number. One of the results shows that the optimum heat loss, fin effectiveness and fin length increase linearly with the inner radius of the pipe when both the fin volume and fin-base radius are fixed.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.14-22
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• 2007

A reversed trapezoidal fin with variable lateral surface slope is optimized using a two-dimensional analytic method. For a fin base boundary condition, convection from the inside fluid to the inside wall and conduction from the inside wall to the fin base are considered. Heat loss from the fin tip surface is not ignored. The maximum heat loss at the practical fin length, the corresponding optimum fin efficiency, fin length and fin base height are presented as a function of the fin inside and outside convection characteristic numbers. One of the results shows that the optimum fin shape becomes 'fatter and shorter' as the ratio of fin tip height to base height increases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.9
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• pp.711-717
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• 2003

This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The frost behaviors of the staggered fin array are somewhat different from those of in-line array. The frost layer formed on the first fin of the in-line array grows rapidly, compared to second fin, whereas the difference of the frost layer growth between the fins of the staggered array is small. For fin pitch below 10 m, the frost layer growth of second fin in the staggered array is affected by that of first fin. The thickness of the frost layer and heat transfer of single fin are reduced with decreasing fin pitch regardless of fin array. However, the thermal performance of a heat exchanger is enhanced due to the increase of heat transfer surface area.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.1
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• pp.55-65
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• 2017

Underwater torpedo has control fin with very low aspect ratio due to launching from limited size of cylindrical torpedo tube. If the aspect ratio of control fin of underwater vehicle is very low three-dimensional flow around control fin largely reduces control forces. In this study, the end plate was applied to reduce the three-dimensional flow effects of partially movable control fin of underwater vehicle. Through numerical simulations the flow field around control fin was examined with and without end plate for different flap angles. The pressure, vorticity, lift and torque on the control fin were analyzed and compared to experiments. The comparison have shown a reasonable agreement between numerical and experimental results and the effect of end plate on a low aspect ratio control fin. When the end plate was attached to the movable control fin, the lift increased and the actuator shaft torque did not significantly change. As this means less consumption of the actuator shaft torque compared to the control fin that has the same control force, the inner actuator capacity can be reduced and energy consumption can be saved. Considering this, it is expected to be effectively applied to the control fin design of underwater vehicles such as torpedoes.

• Journal of Convergence for Information Technology
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• v.11 no.11
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• pp.159-165
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• 2021

A fin channel with a fin width of 20 nm and a gradually increased source/drain extension regions are fabricated on a bulk silicon wafer by using a three-dimensional selective oxidation. The detailed process steps to fabricate the proposed fin channel are explained. We are demonstrating their preliminary characteristics and properties compared with those of the conventional fin field effect transistor device (FinFET) and the bulk FinFET device via three-dimensional device simulation. Compared to control devices, the three-dimensional selective oxidation fin channel MOSFET shows a higher linear transconductance, larger drive current, and lower series resistance with nearly the same scaling-down characteristics.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.35-42
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• 2013

In this paper, the analog performance of FinFET structure was estimated by extracting the DC/AC characteristics of the 22 nm process FinFET structures with different layout considering spacer and SEG using 3D device simulator, Sentaurus. Based on the analysis results, layout methods to enhance the analog performance of multi-fin FinFET structures are proposed. By adding the spacer and SEG structures, the drive current of 1-fin FinFET increases. However, the unity gain frequency, $f_T$, reduces by 19.4 % due to the increase in the total capacitance caused by the added spacer. If the process element is not included in multi-fin FinFET, replacing 1-finger with 2-finger structure brings approximately 10 % of analog performance improvement. Considering the process factors, we propose methods to maximize the analog performance by optimizing the interconnect and gate structures.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.105-116
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• 2015

In this study, airside performance of round fin-and-tube heat exchangers are compared with that of the herringbone wave fin-and-tube heat exchangers with an aim to investigate the effect of fin shape on thermal performance. Results show that j factors of the round wave fin are 1.2~22% larger than those of herringbone wave fin. The f factors of the round wave fin are -1.0~29% smaller than those of herringbone wave fin for 1 or 2 row configuration. For 3 row configuration, f factors of the round wave fin are 8.3~23% larger. The reason may be attributed to the reduced recirculation zone in the valley of the fin for round wave fin as compared with that of the herringbone wave fin. For round wave fin, the effect of fin pitch on j and f factor is not significant. In addition, j factors decrease as the number of tube row increases. On the other hand, f factors are independent of the number of tube row. A new correlation was developed based on the present data.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2091-2096
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• 2007

This paper presents a mathematical model for predicting the frost behavior formed on heat exchanger fins, considering fin heat conduction under frosting condition. The model is composed of air-side, the frost layer, and fin region, and they are coupled to the frost layer. The frost behavior is more accurately predicted with fin heat conduction considered (Case A) than with a constant fin surface temperature assumed (Case B). The results indicate that the frost thickness and heat transfer rate for Case B are over-predicted in most regions of the fin, as compared to those for Case A. Also, for Case A, the maximum frost thickness varies little with the fin length variations, and the extension of the fin length over 30 mm contributes insignificantly to heat transfer.

• The Journal of Korea Robotics Society
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• v.9 no.4
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• pp.225-231
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• 2014

Fish generates thrust with a compliant fin which is known to increase the efficiency. In this paper, the performance of a robotic dolphin, the velocity and the stability, was improved using an optimal compliant caudal fin under certain oscillating frequency. Optimal compliance of the caudal fin exists that maximizes the thrust at a certain oscillating frequency. Four different compliant fins were used to find the optimal compliance of the caudal fin at a certain frequency using the half-pi phase delay condition. The swimming results show that the optimal compliant fin increases the velocity of the robotic fish. The compliance of the caudal fin was also shown to improve the stability of the robotic fish. A reactive motion at the head of the robotic dolphin causes fluctuation of the caudal fin. This phenomenon increases with the oscillating frequency. However, compliant fin reduced this fluctuation and increased the stability.