• 전기학회논문지P
• /
• 제60권4호
• /
• pp.200-205
• /
• 2011

In multipath fading channel, diversity is essential to mitigate the impairments. In this paper, we have proposed the angle diversity scheme called ATTD(Angle Time Transmit Diversity) instead of Alamouti's STTD(Space Time Transmit Diversity) and have analyzed the performance of the proposed scheme when signal powers caused by the transmission to different angles are different. Based on it, we have measured the wireless vector-channel in the urban area, which has lots of high-story buildings, using the data collected from the 8 by 4 smart array antenna system that we made. According to the measured data, the received signals from different angles have different signal powers. Our performance analysis results show that the proposed scheme has better performance than the space diversity scheme when the received path signal power is at least -7dB compare to the strongest path signal power.

• 한국전자파학회논문지
• /
• 제14권3호
• /
• pp.239-243
• /
• 2003

본 논문에서는 0~360도까지의 모든 방향으로부터 신호광을 수신할 수 있는 수광각 다이버시티 무선광검출기를 구성하였다. 8개의 포토다이오드를 사용하여 수광각 다이버시티를 구성하고 수광각에 따른 검출전압의 변동을 줄이기 위하여 디지털가변저항을 사용하여 출력전압을 안정화하였다. 안정화상태에서 수광각에 따른 전압 변동은 최대검출전압의 약 1/10 이내로 유지되었다. 이 구조는 무선광연결에서 전방향수신기를 구현하는 데에 매우 유용하게 사용될 수 있다.

• 한국디지털건축인테리어학회논문집
• /
• 제11권4호
• /
• pp.39-46
• /
• 2011

This Study is about the Axis used for creating forms of interior spaces in representative works of Peter Eisenman architecture. The plans, elevations, photos of interior spaces of his architecture were collected and analysed. In conclusion, the methods using axises were classified in the axises crossing right angle and the rotating axises crossing right angle. The rotating axis were divided into one-angle rotating and multi-angle rotating. The axises were rotated on the plan or rotated on the elevation. The axises crossing right angle were used for dividing, assembling, transforming and composing different proportions of rectangles in interior spaces. The rotating axises crossing right angle were used for creating divers forms such as triangle, quadrilateral, and polygon. The one-angle rotating emphasizes directions of axises in interior spaces. The multi-angle rotating emphasizes decentered directions in interior spaces. The parts created while crossing axises three-dimensionally were opened or filled. The axises were used dynamically and three-dimensionally for diversity of forms in interior spaces of Peter Eisenman architecture.

• 한국멀티미디어학회논문지
• /
• 제11권12호
• /
• pp.1697-1705
• /
• 2008

Several studies made for wireless mesh networks aim to optimize the capacity for wireless networks. Aside from protocol improvements, researches were also done on the physical layer particularly on modulation techniques and antenna efficiency schemes. This paper is concerned with the capacity improvements derived from using spatial diversity with smart adaptive array antennas. The use of spatial diversity, which has been widely proposed for use in cellular networks in order to lessen frequency re-use, can be used in mesh networks both to minimize co-channel interference (CCI) and enable multiple transmissions. This paper aims to study the capacity region and bounds in using smart antennas for single-channel multi-radio systems in relation to the number of spatial diversity or sectors as defined by the beam angle $\beta$.

• 한국자원식물학회지
• /
• 제21권3호
• /
• pp.216-221
• /
• 2008

The Purpose of this study was to offer the raw data for drawing up the conservation plan by analysing natural vegetation in Midongsan, Chungcheongbuk-do, Korea. The period of survey was from July to October, 2004 and the size of plot was 100$m^2$. In the results of analyzing the physical environments, the range of altitude was 303${\sim}$550m and soil pH was 5.4${\sim}$6.8. The angle of slope was 3${\sim}$57% and topographical factor was composed of ridgeline. In the results of analyzing a importance percentage, the dominant species in tree layer, Pinus rigida, P. densiflora, Quercus mongolica, Q. variabilis and Q. acutissima, P. rigida, Q. mongolica, Q. acutissima, Platycarya strobilacea and Q. variabilis in subtree layer, Rhododendron mucronulatum, Symplocos chinensis for pilosa, Lindera obtusiloba, L. erythrocarpa, Rhus trichocarpa and Weigela subsessilis in shrub layer. In the results of species diversity index, species diversity (H') was from 1.2401 to 2.5540, maximum species diversity (H'max), from 1.9459 to 2.8904, evenness (J'), from 0.5644 to 0.8836, dominance (D), from 0.1164 to 0.4356.

• 조명전기설비학회논문지
• /
• 제26권6호
• /
• pp.8-15
• /
• 2012

In this paper, we investigated possible optical parameters causing deviation of experimentally observed output spectra from theoretically predicted results in a high-order fiber comb filter based on a polarization-diversity loop configuration. They include wavelength dependency of half-wave plates (HWPs) inserted in the filter for wavelength switching and the modal birefringence of single-mode fibers (SMFs) with which optical components comprising the filter are connected. In order to consider the effect of the modal birefringence of the SMF on a filter performance, it is modeled as a low birefringence fiber with an arbitrary orientation angle and birefringence. It is found from the simulation results that the modal birefringence of SMFs strongly affects the spectral characteristics of the filter and decreases the extinction ratio of the filter, compared with the wavelength dependency of HWPs. In particular, it is also confirmed that the spectral deviation and asymmetric distortions of side-lobes in narrow band transmission spectra result mainly from the modal birefringence of SMFs.

• 조명전기설비학회논문지
• /
• 제29권12호
• /
• pp.1-7
• /
• 2015

In this paper, we propose a second-order fiber flexible comb filter based on a polarization-diversity loop(PDL). The proposed filter consists of a polarization beam splitter, four half-wave plates(HWPs), and three high birefringence fiber(HBF) segments. In the previous Solc-type second-order filter based on the PDL, HBF segments were fusion-spliced with a fixed angle offset between their principal axes with each other. But, the proposed filter implemented by inserting two HWPs between three HBF segments has a great flexibility in adjusting relative angular difference between the principal axes of two adjacent HBF segments. Owing to this flexibility, second-order transmission spectra, which had a channel spacing of ~0.8nm, could be interleaved by controlling the orientation angles of four HWPs. The output transmission spectra of the proposed filter were theoretically analyzed and experimentally verified.

• 한국통신학회논문지
• /
• 제33권4C호
• /
• pp.336-341
• /
• 2008

본 논문에서는 신호의 반 파장 간격으로 안테나 소자를 배치한 빔형성 시스템에서 다이버시티 이득을 얻을 수 있는 빔형성 알고리즘을 제안한다. 제안된 알고리즘은 수신 신호 공간을 스팬(span)하는 고유 벡터들을 이용하여 빔형성 한다. 본 논문에서는 채널 추정을 위한 최적의 고유 공간 차수를 정하기 위한 기준도 제안한다. 제안된 알고리즘을 적용한 빔형성 시스템은 기존의 빔형성 시스템과는 달리 각 퍼짐이 증가함에 따라 다이버시티 이득을 얻어 그 성능이 개선된다. 본 논문은 제안된 알고리즘의 설명과 함께 다양한 컴퓨터 시뮬레이션을 통한 제안 알고리즘의 성능 분석을 제공한다.

• Animal Systematics, Evolution and Diversity
• /
• 제40권1호
• /
• pp.1-15
• /
• 2024

Our study aimed to investigate the diversity of tintinnid species in Korea by collecting samples from coastal waters. As a result, we identified and redescribed three newly recorded species of the genus Tintinnopsis Stein, 1867 and one previously recorded species of the genus Antetintinnopsis Wang et al., 2021 in Korea. The loricae morphology and molecular phylogeny based on the 18S rDNA sequences of these four were analyzed. Tintinnopsis kiaochowensis Yin, 1956 is characterized by having an irregular collar with spiral turns and an obconical-shaped bowl. Tintinnopsis orientalis Kofoid and Campbell, 1929 is characterized by the inverted bell-shaped lorica with size of 121-140×86-94 ㎛. Tintinnopsis parvula Jörgensen, 1912 is characterized by its narrower collar than bowl and acute angle of the bowl (39-75°). The recorded species, Antetintinnopsis gracilis (Kofoid and Campbell, 1929) Wang et al., 2021 is characterized by a cylindrical collar narrower than the bowl width and with a size of 98-131×37-46 ㎛.

• Animal Systematics, Evolution and Diversity
• /
• 제38권1호
• /
• pp.46-49
• /
• 2022

This study newly records a deep-sea coral, Flabellum (Ulocyathus) deludens from Korea. The specimens were collected by trawling at a depth of 100 m off Jejudo Island in 2019. The newly recorded species is described and compared with the other similar consubgeneric species in detail based on morphological characteristics, including corallum size, calicular diameter, calicular edge, face angle, edge angle, and septal arrangement. Flabellum(Ulocyathus) deludens is characterized by its solitary, highly compressed, wedge-shaped corallite with a small cylindrical pedicel, radiating inverse chevron-patterned lateral stripes on thecal faces, highly jagged calicular edges, and hexameral septal arrangement in five cycles. As a result of this study, five species in the family Flabellidae have been recorded from Korea.