• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4735-4741
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• 2010

The ultrasonic metal welding is highly used in extensive field due to the possibility for welding of various materials such as new materials, plated structures and etc, and its welding conditions has been diversify. In this paper, one-wavelength tool horn of step type designed for ultrasonic metal welding of dissimilar metal sheets has performed by FEM analysis. FEM analysis is applied to predict the natural frequency of ultrasonic tool horn and use of in the optimal design of ultrasonic horn shape. And the optimal design of one-wavelength step horn is confirmed experimentally using natural frequency analysis system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.8
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• pp.720-725
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• 2011

Most ultrasonic vibration cutting tools are operated at the resonance condition of the longitudinal vibration of the structure consisting of booster, horn and bite. In this study, a transverse vibration tool with beam shape is designed to utilize the vibration characteristics of the beam. Design point of the transverse vibration tool is to match the resonance frequency of the bite to the frequency of the signal to excite the piezoelectric element in the booster. The design process to match the natural frequency of the longitudinal vibration mode of the horn and that of the transverse vibration mode of the bite is presented. Dimensions of the horn and bite are searched by trend analysis through which the standard shapes of the horn and bite are determined. After the dimensions of each component of the cutting tool consisting of booster, horn and bite are determined, the assembled structure was experimentally tested to verify that true resonant condition is achieved and proper vibrational displacement are obtained to ensure that enough cutting force is generated.

• Progress in Superconductivity and Cryogenics
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• v.24 no.1
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• pp.29-33
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• 2022

Recently, development of a cryogenic fluids storage tank for storing or transporting liquid hydrogen is actively in progress. In cryogenic fluids storage tanks, hydrogen evaporates due to the extreme temperature difference inside and outside the tank. As the mass of the cryogenic fluids changes with continuous vaporization, the fluids level also changes. Therefore, there is need for a method of accurately measuring the level change in the storage tank. In the case of general cryogenic fluids, it is difficult to accurately measure the level because the dielectric constant is very low. As a method of measuring cryogenic fluids level with low dielectric constant, it can be used an Millimeter wave (MM wave) FMCW radar sensor. However, the signal sensitivity is very weak and the level accuracy is poor. In this paper, the signal sensitivity is improved by designing the horn lens antenna of the existing 80 GHz FMCW radar sensor. Horn lens antenna is fabricated by FDM/SLA type 3D printer according to horn and lens characteristics. The horn is used to increase the signal gain and the lens improves the signal straightness. This makes it possible to measure the level of cryogenic fluids with a low dielectric constant.

• Korean Journal of Pharmacognosy
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• v.22 no.3
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• pp.171-182
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• 1991

Several experiments were carried for the purpose of establishing the basis for the quality evaluation of deer horn. Deer horn originated from China, New Zealand, Soviet and Alaska were used as objectives and some constituents involved in deer horn were assayed and compared with one another. Five kinds of trace elements including Ca and Fe were determined by atomic absorbance spectroscopy. The more the region came down from the top of the deer horn, the more the ratio of Ca to Fe content (Ca/Fe) was increased. The same increasing tendancy was observed in the case of ash content. Gangliosides were isolated from deer horn by alumina column chromatography and identified by TLC using gangliosides Type II obtained from bovine brain as the standard material. The TLC chromatograms were scanned by dual wavelength TLC scanner, then those TLC profiles were compared. Deer horn from China and New Zealand were analogous but those from Soviet and Alaska were each distinguished in their TLC profiles.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.4
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• pp.27-31
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• 1990

To calculate the lift of a thin lifting surface like the ship-rudder, it is popular to replace the lifting surface by a series of vortices. Two methods, which are vortex lattice method and mode function method, are frequently used to distribute the vortices on the lifting surface. In this paper, the intermediate way of two mentioned calculation method is carried out to exploit the merits of them. The basic concept of this method is to divide the lifting surface with several strips in span-wise and replace vortices to the chord-wise at each strips. A horn type semi-balanced rudder is chosen for the real method, and the validity of the proposed calculation is pursued by the open water test of the same rudder. Finall, this method is applied to the calculation of the interference between the two homogenous rudders siting parallel to the free stream.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.4
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• pp.543-552
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• 2010

The Coanda effect is noticeable when a jet stream is applied tangential to a curved surface since then the jet stream remains attached to the surface beyond the point where flow separates otherwise and results in augmentation of circulation and lift. Numerous experimental and numerical studies have been performed in various fields of aerodynamics to exploit the Coanda effect and many of them found to be useful. It can be speculated that the Coanda effect may have practical application to the field of marine hydrodynamics as well since various control surfaces are being used to control behaviors of ships and offshore structures. In the present study, the Coanda effect has been applied to a horn type rudder and a series of numerical computations and model experiments are performed to find the practical applicability. The results indicate that the Coanda jet increases the lift coefficient of the rudder as much as 52% at the momentum coefficient $C_j$ = 0.1 and the rudder angle ${\alpha}=10^{\circ}$.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.53-60
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• 2004

We have developed and manufactured an experimental ultrasonic polishing machine with frequency of 20kHz at the power of vibration 1.7㎾ for effective ultrasonic polishing in processing of high hardness material. Design of the horn is performed by the FEM analysis. The following conclusions were empirically deduced through experimental results to clarify the major elements which affect the surface roughness during the ultrasonic process by following the experimental plans. The ultrasonic polishing machine has been developed in parts of structure part, ultrasonic generator, vibrator. We were able to process the high hardness material without difficulty as a result of ultrasonic polishing by utilizing the groove added step-type horn. Through analyzing by applying the experimental plans, the rotating speed of the horn was determined to be the major factor in influencing the surface roughness. In the case of ceramic, wafer, we were able to obtain good surface roughness when the feed rate and the ultrasonic output were higher. Because the load on slurry particle increases when the ultrasonic output is higher, the processed surface becomes worse in the case of optical glass.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.3
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• pp.133-138
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• 2005

This paper presents a characteristics of horizontal swing angle in V type suspension string sets for 765kV T/L. The design of V type suspension string set does not differ from that of general string set for general towers, but it prevents instabilities from swing motion by the horizontal angle and by the wind pressure. We were designed specially 6 conductor yoke, arcing horn and earth horn. And we were decided to 550mm for a distance of strings. We were carried out characteristics of horizontal swing test and movement of mass center test for V-string sets of 400kN single, 300kN double and 400kN double. This products will be used for 765kV T/L of 1 circuit in suspension towers.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.113-121
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• 2010

Recently, as container ships become larger and faster, rudder cavitations are more frequently observed near the gap between the horn and rudder plates of the ships to cause serious damages to the rudder surface of the ship. The authors already have suggested through a series of model experiments and numerical computations that employment of an appropriate blocking device for gap flow may retard the gap cavitation. For examples, a cam device installed near the outer edges of the vertical gap or a water-injection device combined with a pair of half-round bars installed inside the gap can considerably reduce the gap cavitation. However, it is also found that effective blocking of the flow through the vertical gap results in growth of the cavitation near the horizontal gap instead. In the present study, effectiveness of the simultaneous blocking of the flow through the horizontal and vertical gaps of a horn type rudder in minimizing the damage by gap cavitation is studied. Additional blocking disks are inserted inside the horizontal gaps on the top and bottom of the pintle block and numerical computations are carried out to confirm the combined effect of the blocking devices.

• Conservation Science in Museum
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• v.25
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• pp.51-62
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• 2021

The Belt with Rhinoceros-Horn Ornaments(known as a seodae in Korean) from the family of Princess Deokon's descendants housed in the National Hangeul Museum underwent emergency treatment for a special exhibition in 2019 upon the request of the National Hangeul Museum. Priority was given to the restoration of the original form of the severely damaged belt and the repair of its detached horn ornaments. Prior to the conservation treatment, researchers conducted a theoretical study of the belt with rhinoceros-horn adornments to learn the names of its structural components and the changes in form that the type experienced by period, thereby establishing a plan for conservation treatment and setting a direction. Among the belts worn by officials from the Joseon dynasty, rhinoceros-horn ornaments were attached to those of officials of the first rank and were considered the most precious behind the king's belt with its jade ornaments. The rhinoceros horn adorning the belt is classified into three categories according to quality. This belt has horn adornments of the highest quality, falling under the "grape design" category with dark brown dots concentrated in the center. The belt has a rectangular shape and lacks a buckle, reflecting a popular form from the nineteenth century. The structure of the belt was identified over the process of conservation treatment, offering information about its method of production. In addition, comparison of the relic with belts with rhinoceros-horn ornaments depicted in Joseon-period portraits of officials allowed the identification of changes in formal features and the detailed structures of belts with rhinoceros-horn ornaments by period. It confirmed that the belt subject to conservation treatment shows the features of belts with rhinoceros-horn ornaments produced in the nineteenth and twentieth centuries.