• 대한기계학회논문집
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• 제9권6호
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• pp.788-794
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• 1985

본 논문에서는 유동산란입자들을 1개에서 35개까지 불규칙 상태로 배열한 13 가지의 모델을 만들어 probe volume 속으로 횡단시키므로 나타나는 신호를 분석하여 수밀도와 가시도에 대한 실험적 관계를 파악하고 이를 이론식과 비교검토하고자 했다. 또한 두 입자의 간격을 좁혀가면서 실험하므로 간섭무늬에 대한 두 입자의 입상차가 합성신호특성에 중요 파라미터임을 확인했다.

• 마이크로전자및패키징학회지
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• 제11권2호
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• pp.43-47
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• 2004

전력 결합기 및 전력 배분기는 마이크로파 수동 소자의 일종으로 전력을 결합하거나 나눌 때 쓰이는 것이다. 최근의 정보통신 시스템의 추세를 보아 수동 소자의 집적화 및 소형화가 요구된다. 본 연구에서는 이러한 추세를 감안하여 2012 크기의 다층 구조를 적용한 양대역 방향성 결합기를 저온 동시소성 기술을 활용하여 제작하였다. DCS(Digital communication system)와 EGSM(European global system for mobile) 대역에서 각기 원하는 커플링을 얻기 위해서 수직 결합 패턴들을 다층 구조에 적용하였다. 제작된 방향성 결합기의 결합성, 삽입 손실, 격리성 및 방향성 등의 특성들을 측정하였고 시뮬레이션 결과들과 비교 고찰하였다.

• 한국전자파학회논문지
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• 제13권6호
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• pp.574-581
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• 2002

본 논문에서는 이동차량에서 위성과의 송, 수신 양방향 서비스와 위성 방송 수신을 목적으로 하는 능동 위상 배열 마이크로스트립 안테나를 위한 8$\times$2부 배열을 설계, 제작, 측정하였다. 수신 11.7-12.75 GHz, 송신 14-14.5 GHz 대역에 대하여 단일 소자로 송, 수신을 위하여 $\pm$45$^{\circ}$ 직교화 된 두 개의 선형 편파를 사용한다. 수신 대역의 광대역 특성을 위하여 두 패치 사이의 이중 공진을 이용하였고, 공기층의 두께를 조절하여 20 dH 이상의 격리도 특성을 보였다. 앙각 방향에 대하여 전기적으로 30$^{\circ}$ 빔 틸트 하였으며 낮은 부엽 수준을 위하여 테이퍼형 전력분배와 좁은 소자간 간격을 사용하였다.

• 한국기계가공학회지
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• 제20권2호
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• pp.1-7
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• 2021

A computer simulation was performed to study the effectiveness of temperature on the type of laser heat source in the context of the heterogeneous welding of aluminum and copper materials. Three different types of heat sources were used in the computer simulation: 1) Single Beam Straight Scan, 2) Single Beam Wobble Scan, and 3) Dual Beam Straight Scan. Among these sources, dual beam straight scan was found to be the most effective from the viewpoint of heat source control. Because the difference between the melting temperatures of copper and aluminum is approximately 400℃, a clear separation of heating temperature was required, and the dual beam straight scan provided superior controllability in this regard. When using the dual beam, the temperature of the 90:10 split was considerably easier to control than that of the 50:50 split. The optimal offset was calculated to be 4 mm off to the copper side, where the melting temperature and thermal conductivity were higher. In this manner, computer simulation was effectively used for determining the optimal laser beam hear source control without performing an actual laser welding experiment.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2633-2640
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• 2024

The purpose of this study was to investigate the effect of the reflector, surface treatment, and length of scintillation crystals on the performance of a time-of-flight and depth-of-interaction (TOF-DOI) PET detector with a dual-ended readout and to determine the best reflector and surface treatment. Various types of crystal arrays with three different reflectors (ESR, BaSO₄, and Toray), three different lateral surface treatments (all-polished (AP), all-roughened (AR), and partially roughened (PR, three sides polished, and one side roughened)), and two different lengths (20 and 15 mm) were fabricated. The highest light collection efficiency and best energy resolution were achieved using a crystal with a diffuse reflector (BaSO₄ for AP and Toray for AR). In contrast, the best coincidence timing resolution (CTR) was achieved using an AR crystal with a specular reflector (ESR). The best DOI resolution was achieved using an AR crystal with BaSO₄. Moreover, the results measured with the 20 mm long crystals were similar to those measured with the 15 mm long crystals. Therefore, we concluded that the dual-ended readout PET detector employing the crystal with AR lateral surface treatment and ESR was a good candidate for TOF-DOI PET because it provided excellent CTR and adequate DOI resolution.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2009년도 학술발표대회
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• pp.207-208
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• 2009

• Archives of Plastic Surgery
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• 제34권1호
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• pp.93-98
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• 2007

Purpose: Many options are available for the incision and pocket selection in breast augmentation. Each method has its advantages and disadvantages. To leave an invisible operation scar and to achieve easier pocket dissection by the central location of the incision on the breast, we made a transareolar-perinipple incision. To overcome the disadvantages of the transareolar incision, originally advocated by Pitanguy in 1973, we modified the direction of incision line and dissection plane. Methods: To avoid the injury of 4th intercostal nerve responsible for nipple sensation, we made perinipple incision on the medial side of the nipple instead of trans-nipple incision and made the transareolar incision as 11-5 o'clock on the left side and 1-7 o'clock on the right side instead of 3-9 o'clock on both sides. To avoid the possible infection and breast feeding problem caused by the injury to the lactiferous duct, and the possible implant hernia caused by the incisions lying on a same plane of pocket dissection, we made a subcutaneous dissection just above the breast tissue medially down to the bottom of breast tissue and made a subglandular or subfascial pocket, which may avoid the injury of lactiferous duct and create different planes for skin incision and pocket dissection. Other advantages of the transareolar-perinipple incision include easier pocket dissection, less chance of hematoma, and as a result less postoperative pain because of the central location of the approach which allow finger dissection and meticulous bleeding control with direct vision, without any specialized instrument such as an endoscope or long mammary dissectors. As for pocket selection, we made dual pockets. We prefer subglandular or subfascial pocket. Also, we made a subpectoral pocket in the upper 1/4 of the pocket to add more volume on the upper part of the augmented breast, which can make aesthetically more desirable breasts in thin Asian women with small breasts. Possible disadvantages of our method are subclinical infection and scar widening, which could be overcome by meticulous operation techniques, antibiotic therapy, and intradermal tattooing. Results: From September, 2003 to August, 2005, 12 patients underwent breast augmentation using round smooth surface saline implants by our method. During the mean follow-up period of 13 months, there were no complications such as infection, hematoma, capsular contracture, and sensory change of nipple, and results were satisfactory. Conclusion: We suggest breast augmentation via transareolar-perinipple incision and dual pockets(subpectoral-subglandular or subfascial) as a valuable method in thin oriental women with small breasts.

• 한국광학회지
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• 제14권3호
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• pp.331-337
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• 2003

본 연구는 이중 이온빔 스퍼터링 증착법으로 제작한 채널 간격 50 ㎓ 광통신용 협대역 투과 필터에 관한 연구이다. Ta$_2$ $O_{5}$ 단층박막의 특성 분석을 통해 공정 조건을 최적화 하였으며, DPS 필터 예비 증착을 통해 0.1 nm 이하의 박막두께 균일성을 확보하였다. 1/4 파장 광학박막 두께를 기본으로 하여 총 216층으로 구성되고 4개의 간격층을 갖는 채널 간격 50 ㎓ 협대역 투과 필터를 설계하였고, 파장 가변 레이저를 사용한 비접촉 광학 두께 제어 시스템을 사용하여 증착하였다. 박막 증착시 발생하는 스트레스를 줄이기 위하여 열팽창 계수가 큰 유리 기판을 사용하였으며, 비접촉 광학 두께 제어 시스템의 오차를 줄이기 위하여 협대역 투과 필터의 제작에 앞서 기판의 뒷면에 무반사 증착을 수행하였다. 이렇게 제작된 채널 간격이 50 ㎓인 협대역 투과 필터의 광학 특성은 삽입 손실이 0.40 ㏈, 잔물결이 0.20 ㏈이며,-0.5 ㏈와 -25 ㏈에서의 투과 대역폭이 각각 0.20 nm, 0.60 nm로 광통신에서 사용되는 사양을 만족하였다.하였다.

• Journal of Positioning, Navigation, and Timing
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• 제9권2호
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• pp.117-124
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• 2020

In this paper, the symmetric position drift of the integration approach in pedestrian dead reckoning (PDR) system with dual foot-mounted IMU is analyzed. The PDR system that uses the inertial sensor attached to the shoe is called the IA-based PDR system. Since this system is designed based on the inertial navigation system (INS), it has the same characteristics as the error of the INS, then zero-velocity update (ZUPT) is used to correct this error. However, an error that cannot be compensated perfectly by ZUPT exists, and the trend of the position error is the symmetric direction along the side of the shoe(left, right foot) with the IMU attached. The symmetric position error along the side of the shoe gradually increases with walking. In this paper, we analyze the causes of symmetric position drift and show the results. It suggests the possibility of factors other than the error factors that are generally considered in the PDR system based on the integration approach.

• 한국군사과학기술학회지
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• 제16권6호
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• pp.811-818
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• 2013

In this paper, we have designed the elliptical dual offset gregorian antenna which can use Ka band earth station antennas in the fixed-satellite service. The structure of antenna is increasing the antenna gain by decreasing blockage areas and decreasing wind effects by shortening height of the antenna. The corrugate horn antenna for this antenna has symmetric radiation patterns and low side lobe levels that can meet ITU-R envelope. The distribution of electric field on a aperture of main reflector is calculated by an ray-tracing method that use the radiation pattern of the feed horn. The final geometric of antena is decided by choosing the distribution that comply with antenna requirement. The FEKO analysed electrical performance of this antenna. The fabricated antenna has 45.0dBi(@30.0GHz)/41.7dBi(@20.2GHz), high efficiency and low side lobe level that meet ITU-R S. 580-6 envelope.