• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.7
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• pp.613-619
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• 2015

In this paper, we proposed a paper-based pattern-switchable antenna using inkjet-printing technology. The proposed antenna is composed of two bow-tie antennas and a switching network. The bow-tie antennas are inkjet-printed on paper using a low cost home printer. The switching network is built on a printed-circuit-board(PCB) and consists of a single-pole-double-throw(SPDT) switch and balun element. A double-sided parallel-strip line(DSPSL) can convert the unbalanced microstrip mode to the balanced strip mode. Two bow-tie antennas have different radiation patterns because of the different orientation of the reflectors. It is demonstrated from EM simulation and measurement that the radiation patterns of the proposed antenna are successfully switched by the SPDT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.195-201
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• 2004

In this paper, U-Shaped slot Bow-Tie antenna for 5.15㎓∼5.35㎓ is designed, fabricated, and measured. The prototype consist of U-Shaped slot. To obtain suitable bandwidth, the form layer is inserted between ground plane and substrate. Important parameters in the design are U-slot length, width, position, air-gap height, and feed point position. From these parameters optimized, a U-shaped slot Bow-Tie antenna is fabricated and measured. The measured results of the antenna are obtained as follows results. The resonant frequency of the Fabrication U-shaped slot Bow-Tie antenna is 5.28㎓, bandwidth for approximately 7.76％(VSWR<1.2) and the gain is 4∼7dBi. The experimental far-field patterns are stable across the pass band. The 3dB bandwidth in Elevation and Azimuth are 73.63$^{\circ}$and 65.08$^{\circ}$, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1455-1461
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• 2000

There are many researches to increase bandwidth of the microstrip patch antenna for wireless LAN. In spite of broad bandwidth, Bow-Tie antenna has disadvantages that are low gain and big size. In this paper, stacked Bow-Tie microstrip patch antenna for wireless LAN is designed in 5.725 ~5.825 GHz band. This antenna has characteristics that are broadband bandwidth, high gain and small size compared with microstrip patch antenna. In simulated results, the return loss is -34.2 dB at 5.78 GHz and bandwidth is 11.345% for VSWR 2:1 and 7.75%for VSWR 1.5:1. In measured results, the return loss is -38.45 dB at 5.78 GHz and bandwidth is 13% for VSWR 2:1 and 5.6% for VSWR 1.5:1. It has 73.16$^{\circ}$ -3dB beam width and 6.5dB gain.

• Journal of the Korean Institute of Gas
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• v.24 no.4
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• pp.73-83
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• 2020

The problem addressed in this study is that the reduction in process accidents is less than the reduction in industrial safety, and the losses from major accidents in the oil and gas processing industry have not decreased over the years. In particular, current risk approaches in storage tanks place more emphasis on improving the safety of the design than maintaining safe operation. The Bow-Tie method can be used properly to improve process safety. The Bow-Tie method can assess compliance by focusing on operational aspects, clearly highlighting all important safety barriers, and analyzing barrier effectiveness.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.5
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• pp.689-696
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• 2010

Bulbous bow is one of the important design factors on the design of fore-body hull form. Using the interference technique of ship waves, the bulbous bow can decrease the wave resistance of ship. Recently, the goose neck bulb is applied mainly for high speed vessels like passenger ships and ferries etc.. Also, the goose neck bulb is applied for relatively high speed merchant vessels like container ships and LNG carriers. However, existing research papers about the goose neck bulb are not enough as reference data for the design of bow hull form. In this study, numerical calculations are carried out to investigate the bow wave characteristics of a high speed ferry with a normal high nose bulb or a goose neck bulb. By comparing the pressure distributions on the hull surface and the wave systems near the bow, the features of wave resistance reduction are discussed. Also, Numerical calculations were carried out for a series of goose neck bulbs to figure out the optimum bulb size. The maximum reduction rate of pressure resistance for the fore-body is achievable up to 8% by adopting the goose neck bulb in the present calculation.

• 한국기계연구소 소보
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• v.4 no.2
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• pp.41-48
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• 1982

• The Journal of the Korean dental association
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• v.21 no.10 s.173
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• pp.771-775
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• 1983

• Journal of Astronomy and Space Sciences
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• v.28 no.1
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• pp.17-26
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• 2011

Bow shock, formed by the interaction between the solar wind and a planet, is generated in different patterns depending on the conditions of the planet. In the case of the earth, its own strong magnetic field plays a critical role in determining the position of the bow shock. However, in the case of Mars of which has very a small intrinsic magnetic field, the bow shock is formed by the direct interaction between the solar wind and the Martian ionosphere. It is known that the position of the Martian bow shock is affected by the mass loading-effect by which the supersonic solar wind velocity becomes subsonic as the heavy ions originating from the planet are loaded on the solar wind. We simulated the Martian magnetosphere depending on the changes of the density and velocity of the solar wind by using the three-dimensional magnetohydrodynamic model built by modifying the comet code that includes the mass loading effect. The Martian exosphere model of was employed as the Martian atmosphere model, and only the photoionization by the solar radiation was considered in the ionization process of the neutral atmosphere. In the simulation result under the normal solar wind conditions, the Martian bow shock position in the subsolar point direction was consistent with the result of the previous studies. The three-dimensional simulation results produced by varying the solar wind density and velocity were all included in the range of the Martian bow shock position observed by Mariner 4, Mars 2, 3, 5, and Phobos 2. Additionally, the simulation result also showed that the change of the solar wind density had a greater effect on the Martian bow shock position than the change of the solar wind velocity. Our result may be useful in analyzing the future observation data by Martian probes.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.297-308
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• 2003

Face-bow is used to transfer models to the articulator in diagnosing the patient or treating problems associated with occlusion. However, there have been few reports on the reliability of the face-bow procedure and the relationship between the experience of the operator and the reliability of the face-bow procedure. The purposes of this study are to examine the reliability of the face-bow procedure and to evaluate whether the face-bow transferring has any training effect. Nine dentists working at M hospital conducted a face-bow transfer in one patient having a normal dentition and interdental relationship. The procedure was done two times a week for four weeks. The maxillary model was mounted to the articulator every time, then the landmarks on the maxillary right first molar, the maxillary left central incisor, and the maxillary left first molar were measured with a special three-dimensional instrument. These data were input into a computer, and evaluated statistically. The results were as follows ; 1. When examined with ANOVA test, the results were p=0.2040 in maxillary right first molar, p=0.0578 in maxillary left incisor, and p=0.1433 in maxillary left first molar. There was no significant(0< $p{\leq}0.05$). 2. Training 1) The correlation coefficient between trial and rejection was -0.578 when analyzed with T-distribution. The more we tried, the less errors we found. 2) When the S.D. of the first three trials was compared to the S.D. of the last three trials in face-bow transfer, the results showed that the former was larger than the latter in thirty-nine times, and the latter was larger than the former in fifteen times. The more we tried face-bow transfer, the less errors we found. 3. When the S.D. of x, y, z coordinates were examined, the S.D. of x coordinates had the largest measurement in five times, the S.D. of y coordinates had the largest measurement in four times, and the S.D. of z coordinates had the largest measurement in nine times. The possibility which the error can occur in z coordinate was the highest.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.477-483
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• 2016

The spring-back and bow phenomenon in the roll forming process are important factors regarding the accuracy of evaluation of production goods. The purpose of this study was to determine the influence of spring-back and bow phenomenon according to the main variables (forming velocity and roll gap). The material of the forming sheet was high tension steel (SPFH 590), which has been used commonly in recent years. In order to accurately measure the spring-back and bow phenomenon, the forming sheet was formed into a V-shape. The study was applied to OFAT (One Factor at a Time) experimentation, with respect to the experimental variables (the forming speed and the roll gap). In the experimental results, the forming speed had a small influence on the spring-back and bow phenomenon. However, the roll gap had a greater influence on the springback and the bow phenomenon, as opposed to the forming speed.