• 한국전자파학회논문지
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• 제26권7호
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• pp.613-619
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• 2015

본 논문에서는 잉크젯 프린팅 기술을 이용한 새로운 종이 기반의 방사패턴 가변 안테나를 제안한다. 제안된 안테나는 2개의 bow-tie 안테나와 스위칭 네트워크로 구성되어 있다. 2개의 bow-tie 안테나는 종이의 앞면과 뒷면에 일반 가정용 잉크젯 프린터로 인쇄되었고, 스위칭 네트워크는 PCB 기판에 SPDT와 발룬으로 제작하였다. 복잡한 신호 인가와 발룬 소자의 사용 대신 두 개의 마이크로스트립 선로를 평행하게 위치시킴으로 불 평형 신호를 평형 신호로 바꿔주는 발룬의 역할을 대신하였다. 2개의 bow-tie 안테나에 다른 방향으로 반사체를 추가함으로써 각각의 방사패턴을 서로 다르게 하였다. 제안된 가변형 안테나는 EM 시뮬레이션과 측정 결과를 통해 성공적으로 방사패턴이 가변됨을 확인할 수 있다.

• 한국통신학회논문지
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• 제29권2A호
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• pp.195-201
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• 2004

본 논문에서는 5.15-5.35GHz 대역의 무선 LAN용 U-슬롯 Bow-Tie 마이크로스트립 안테나에 관하여 연구하였다. Bow-Tie 패치에 U-슬롯을 갖도록 하였으며 접지면과 기판사이에 공기층을 삽입하여 VSWR<1.2 에서 적절한 대역을 얻고자 하였다. 설계시 주요 파라미터는 U-슬롯의 길이, 폭, 위치와 공기층의 두께 및 급전위치였으며 최적화된 파라미터를 가지고 실제 제작 및 측정하였다. 제작된 안테나의 측정결과로 공진주파수는 5.28GHz이고, VSWR<1.2에서 7.76%의 대역폭과 4∼7dBi의 이득을 얻었다. Elevation과 Azimuth에서 각각 73.63$^{\circ}$와 65.08$^{\circ}$로 나타났다.

• 한국전자파학회논문지
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• 제11권8호
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• pp.1455-1461
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• 2000

무선 LAN용 안테나로 주로 사용하는 마이크로스트립 패치 안테나에 대역폭을 증가시키기 위한 여러 가지 연구가 활발히 이루어지고 있다. 광대역 마이크로스트립 패치 안테나인 Bow-Tie 마이크로스트립 패치 안테나의 경우 대역폭이 비교적 넓지만 상대적으로 이득이 낮고 크기도 크다는 단점이 있다. 본 논문에서는 넓은 대역폭을 가지며 중심푸자수에서 상대적으로 이득이 높고 작은 크기를 가지는 적층 구조의 Bow-Tie 마이크로스트립 패치 안테나를 무선 LAN용 주파수인 5.725~5.825GHz 대역에 맞추어 설계하였다. 제안된 안테나는 모의 실험상에서 중심주파수가 5.78GHz일 때 반사손실이 약 -34.2 ㏈이고 VSWR 2:1 일 때 약 11.34%, VSWR 1.5:1일 때 7.4%의 대역폭을 가지며 제작된 실제 적층 구조의 Bow-Tie 마이크로스트립 패치 안테나의 경우 반사손실이 5.78 GHz에서 약 -38.45 ㏈이며 VSWR 2:1일 때 약 13%, VSWR 1.5:1일 때 5.6%의 대역폭을 가지며, -3㏈ 빔폭은 73.16$^{\circ}$, 6.5 ㏈의 이득을 가졌다.

• 한국가스학회지
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• 제24권4호
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• pp.73-83
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• 2020

본 연구에서 다루고 있는 문제점은 공정 사고 감소는 산업 안전 감소보다 덜 감소하고 있으며, 석유 및 가스 공정산업의 주요 사고로 인한 손실은 지난 몇 년 동안 감소하지 않고 있는 상태이다. 특히 저장탱크에서 현재의 위험 접근 방식은 안전운전을 유지하는 것에 비해 설계의 안전성을 향상시키는 것에 더 중점을 두고 있다. 이에 Bow-Tie 방법을 활용하여 적절하게 사용한다면 공정의 안전성을 향상시킬 수 있다. Bow-Tie 방법은 운영적인 측면에 초점을 맞추고 모든 중요한 안전 배리어를 명확하게 강조하고 배리어 효율성을 분석하여 적합성을 평가 할 수 있다.

• 대한조선학회논문집
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• 제47권5호
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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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• 제4권2호
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• pp.41-48
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• 1982

• 대한치과의사협회지
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• 제21권10호통권173호
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• pp.771-775
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• 1983

• Journal of Astronomy and Space Sciences
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• 제28권1호
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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.

• 구강회복응용과학지
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• 제19권4호
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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.

• 한국정밀공학회지
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• 제33권6호
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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.