모노펄스 추적을 이용한 무인기 DoA 추정정밀도 향상 방안에 관한 연구 (A Study on UAV DoA Estimation Accuracy Improvement using Monopulse Tracking)
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- 한국전자통신학회논문지
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- 제12권6호
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- pp.1121-1126
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- 2017
비행체의 위치정보는 GPS 교란과 같은 위험성에 노출될 수 있기 때문에 위치를 추정하기 위해 관성항법장치와 같은 여러 연구가 수행되고 있다. DoA(: Direction of Arrival) 및 RTT(: Round Trip Time)을 이용한 위치추정 기법은 레이다시스템에 적용되어 비행체의 위치를 추정하는데 사용되고 있으며 무인기 데이터링크에 적용 가능하다. 무인기 데이터링크는 넓은 대역폭을 사용하기 때문에 다중혼 방식의 합 차패턴 생성 방식을 주로 사용하며 탑재체의 제한된 송신출력으로 낮은 SNR 영역을 포함하여 추적을 수행한다. 일반적으로 낮은 SNR에서 위치 추정오차는 증가하며 높은 SNR에서 부엽을 제한하지 못하면 추정된 DoA의 유효성이 상실된다. 본 논문에서는 부엽을 제한하고 낮은 SNR에서 증가하는 DoA 추정오차를 보정하기 위한 방안을 제시한다.
Objectives: This study assessed the shape and anatomical relationship of the mental foramen (MF) to mandibular posterior teeth in an Indian sub-population. Materials and Methods: In total, 475 existing cone-beam computed tomography records exhibiting 950 MFs and including the bilateral presence of mandibular premolars and first molars were assessed. Images were evaluated 3-dimensionally to ascertain the position, shape, and anatomical proximity of MFs to mandibular teeth. The position and shape of MFs were measured and calculated. The Pythagorean theorem was used to calculate the distance between the root apex of the mandibular teeth and the MF. Results: MFs exhibited a predominantly round shape (left: 67% and right: 65%) followed by oval (left: 30% and right: 31%) in both males and females and in different age groups. The root apices of mandibular second premolars (left: 71% and right: 62%) were closest to the MF, followed by distal to the first premolars and mesial to the second premolars. The mean vertical distance between the MF and the nearest tooth apex calculated on sagittal sections was 2.20 mm on the right side and 2.32 mm on the left side; no significant difference was found according to sex or age. The distance between the apices of the teeth and the MF was ≥ 4 mm (left; 4.09 ± 1.27 mm and right; 4.01 ± 1.15 mm). Conclusions: These findings highlight the need for clinicians to be aware of the location of the MF in treatment planning and while performing non-surgical and surgical endodontic procedures.
본 연구는 식품의 안전성에 대한 관심이 고조되면서 위생적인 식육생산을 위한 방법으로 전자선을 조사하여 이화학적 특성 및 지방산화에 미치는 영향을 조사하고자 실시하였다. 공시재료는 한우암소 지육중 육질등급 1+판정(근내지방도 No.7. 육색 No.4, 성숙도 No.1, 조직감 No.1)을 받은 지육(
이 연구의 목적은 상악 유구치의 치근 및 근관의 형태학적 특성을 분석하는 것이다. 2006년 1월부터 2020년 4월까지 서울대학교 치과병원에서 CBCT 및 3D CT를 촬영한 3 - 7세 환자 총 268명(남자 175명, 여자 93명)이 연구에 포함되었으며, 치근 흡수와 치수병변이 없는 총 1002개의 상악 유구치의 치근과 근관 수를 분석하였다. 218개의 치아에 대해 치근과 근관의 형태, 이개각도, 치근과 근관의 길이 및 근관의 단면 형태를 분석하였다. 48개의 치아에 대해서는 Mimics 및 3-Matics software를 사용하여 치근 치수의 부피와 표면적, 치근-치수 비를 측정하였다. 절반 이상이 3개의 치근과 3개의 근관을 가지고 있었다. 좌우측 치아의 대칭성(Cohen's kappa coefficient)은 약 0.63이었다. 치근과 근관의 형태는 상악 제1유구치에서는 직선형이, 제2유구치에서는 곡선형이 많이 관찰되었다. 치근의 이개 정도, 치근과 근관의 길이는 상악 제1, 2유구치 모두 구개측 치근에서 가장 크게 나타났다. 근단부에서 근관의 단면 형태는 주로 ovoid 혹은 round형이었다. 치근 치수의 부피와 표면적, 치근-치수 비는 상악 제1,2유구치 모두 구개측 치근 치수에서 가장 크게 나타났다.
이 논문에서는 내진상세가 적용되지 않은 RC골조의 지진 거동 특성을 파악하였다. 해석 대상 건물은 내진 규준의 적용을 받지 않고 중력하중만을 고려하여 설계되었다. 원형철근이 주철근으로 사용되었으며, 부재는 낮은 수준의 전단력을 견딜 수 있는 최소한의 스터럽이 사용되어 코어 부분의 구속효과는 거의 없다. 평면비정형성을 가진 건물의 경우, 푸쉬오버 해석을 통해서는 비틀림으로 인한 평면상에서 연단부의 손상집중을 파악할 수 없으므로 비선형 동적해석을 사용하는 것이 바람직하다. 섬유요소를 이용한 비선형 동적해석은 양방향 지진하중과 비틀림 거동의 영향을 받는 RC골조의 거동을 성공적으로 예측할 수 있었다. 하지만, 보다 진보된 응답 예측을 위해서는 부착 미끄러짐과 같은 보-기둥 접합부의 국부거동을 정밀하게 나타내는 모델링 요소의 개발이 필요하다.
150 kV급 가스 클러스터 이온 가속기를 제자하여
In order to obtain the most favourable classification system for fishing gears, the problems in the existing systems were investigated and a new system in which the fishing method was adopted as the criterion of classification and the kinds of fishing gears were obtained by exchanging the word method into gear in the fishing methods classified newly for eliminating the problems was established. The new system to which the actual gears are arranged is as follows ; (1)Harvesting gear \circled1Plucking gears : Clamp, Tong, Wrench, etc. \circled2Sweeping gears : Push net, Coral sweep net, etc. \circled3Dredging gears : Hand dredge net, Boat dredge net, etc. (2)Sticking gears \circled1Shot sticking gears : Spear, Sharp plummet, Harpoon, etc. \circled2Pulled sticking gears : Gaff, Comb, Rake, Hook harrow, Jerking hook, etc. \circled3Left sticking gears : Rip - hook set line. (3)Angling gears \circled1Jerky angling gears (a)Single - jerky angling gears : Hand line, Pole line, etc. (b)Multiple - jerky angling gears : squid hook. \circled2Idly angling gears (a)Set angling gears : Set long line. (b)Drifted angling gears : Drift long line, Drift vertical line, etc. \circled3Dragged angling gears : Troll line. (4)Shelter gears : Eel tube, Webfoot - octopus pot, Octopus pot, etc. (5)Attracting gears : Fishing basket. (6)Cutoff gears : Wall, Screen net, Window net, etc. (7)Guiding gears \circled1Horizontally guiding gears : Triangular set net, Elliptic set net, Rectangular set net, Fish weir, etc. \circled2Vertically guiding gears : Pound net. \circled3Deeply guiding gears : Funnel net. (8)Receiving gears \circled1Jumping - fish receiving gears : Fish - receiving scoop net, Fish - receiving raft, etc. \circled2Drifting - fish receiving gears (a)Set drifting - fish receiving gears : Bamboo screen, Pillar stow net, Long stow net, etc. (b)Movable drifting - fish receiving gears : Stow net. (9)Bagging gears \circled1Drag - bagging gears (a)Bottom - drag bagging gears : Bottom otter trawl, Bottom beam trawl, Bottom pair trawl, etc. (b)Midwater - drag gagging gears : Midwater otter trawl, Midwater pair trawl, etc. (c)Surface - drag gagging gears : Anchovy drag net. \circled2Seine - bagging gears (a)Beach - seine bagging gears : Skimming scoop net, Beach seine, etc. (b)Boat - seine bagging gears : Boat seine, Danish seine, etc. \circled3Drive - bagging gears : Drive - in dustpan net, Inner drive - in net, etc. (10)Surrounding gears \circled1Incomplete surrounding gears : Lampara net, Ring net, etc. \circled2Complete surrounding gears : Purse seine, Round haul net, etc. (11)Covering gears \circled1Drop - type covering gears : Wooden cover, Lantern net, etc. \circled2Spread - type covering gears : Cast net. (12)Lifting gears \circled1Wait - lifting gears : Scoop net, Scrape net, etc. \circled2Gatherable lifting gears : Saury lift net, Anchovy lift net, etc. (13)Adherent gears \circled1Gilling gears (a)Set gilling gears : Bottom gill net, Floating gill net. (b)Drifted gilling gears : Drift gill net. (c)Encircled gilling gears : Encircled gill net. (d)Seine - gilling gears : Seining gill net. (e)Dragged gilling gears : Dragged gill net. \circled2Tangling gears (a)Set tangling gears : Double trammel net, Triple trammel net, etc. (b)Encircled tangling gears : Encircled tangle net. (c)Dragged tangling gears : Dragged tangle net. \circled3Restrainting gears (a)Drifted restrainting gears : Pocket net(Gen - type net). (b)Dragged restrainting gears : Dragged pocket net. (14)Sucking gears : Fish pumps.
The purpose of this study is to analogize the appearance of Korean Ancient Architecture in view of the Stone Remains from 3 Kingdom Period to Unificated Shilla Period. But in these period, there is no building remains but some stupas and fine arts. Especially, there are many architectural appearance and revealing signature in these Historical Stone remains. Architectural elements which are analogized by stone remains what has value as historical materials by preservation of original form from 3 Kingdom Preiod to Unificated Shilla Period are as follows : 1) Platform, the representative characteristic of Korean traditional architecture, was frame structure and accumulate structure. And circular or square footing stood a same shape column on it is put on the platform. 2) In the case of column, there used entasis column and inclined column and circular chamfer technique was applied on the top side of it. Upper side of column, capital and head pentrating tie that small bearing block was put on the center of it was joined. And longitu야nal rest(長舌) supported a cross beam. Capital and small bearing block had no bottom heel, and heel side was curved and straight. Centered bracket structure was often used, and multi bracket structure is not used yet. Inward incline technique was used. 3) Inward opening pair door which had lintel, threshold, doorjamb was usually used, Fixing stone was used for structural safety, and circular handle and lock was used for decoration. Handrail was used on the edge of wooden floor for decorative effect and safety. 4) Square rafter and circular rafter were used in the same period and so did flying rafter. Double eaves and single eave were used in the same period but, single eave was usually used. In this period, square rafter was usually used. This would be studied more by comparing with Japanese wooden architecture. 5) Hipped roof was used and half-hipped roof was not used yet. In front of th hip, there are small sculpture called Jap-Sang(雜像), and windbell was hang on the end of the hip rafter. Concave roof tile, convex roof tile, round eaver tile, decorative tile at end of roof ridge were used. Lotus style was well used on the face of roof tile for decoration. From the results of this study, wooden architecture of Unificated Shilla period was simple compare to Koryo dynasty and Chosun dynasty but, it had some brilliant character. It was hard work that analogized the form of non-existent wood architecture of Ancient Korean period by restricted stone remains. But, in addition to the results of this study and research of old documentations, more study should be go on.
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70