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검색결과 888건 처리시간 0.026초

지면효과를 고려한 WIG 선 익형의 공력특성 및 형상최적화 (Aerodynamic Characteristics and Shape Optimization of Airfoils in WIG Craft Considered Ground Effect)

  • 이주희;김병삼;박경우
    • 대한기계학회논문집B
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    • 제30권11호
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    • pp.1084-1092
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    • 2006
  • Shape optimization of airfoil in WIG craft has been performed by considering the ground effect. The WIG craft should satisfy various aerodynamic characteristics such as lift, lift to drag ratio, and static height stability. However, they show a strong trade-off phenomenon so that it is difficult to satisfy aerodynamic properties simultaneously. Optimization is carried out through the multi-objective genetic algorithm. A multi-objective optimization means that each objective is considered separately instead of weighting. Due to the trade-off, pareto sets and non-dominated solutions can be obtained instead of the unique solution. NACA0015 airfoil is considered as a baseline model, shapes of airfoil are parameterized and rebuilt with four-Bezier curves. There are eighteen design variables and three objective functions. The range of design variables and their resolutions are two primary keys for the successful optimization. By two preliminary optimizations, the variation can be reduced effectively. After thirty evolutions, the non-dominated pareto individuals of twenty seven are obtained. Pareto sets are all the set of possible and excellent solution across the design space. At any selections of the pareto set, these are no better solutions in all design space.

여수연안 정치망 어획물의 종조성과 계절변동 (Seasonal Variation of Abundance and Species Composition of Fishes Caught by a Set Net in the Coastal Waters off Yosu, Korea)

  • 김영혜;김종빈;장대수
    • 한국수산과학회지
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    • 제36권2호
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    • pp.120-128
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    • 2003
  • Fishes were caught by a set net in the coastal waters off Yosu, Korea from April to October, 2001, and seasonal variation of abundance and species composition were studied. Fifty two species were identified as fish $(89\%)\;cephalopods\;(10\%)\;and\;crustaeans\;(1\%).$ Of the fishes Engraulis japonicus, Trachurus japonicus and Trichiurus lepturus were dominant species representing $64.1\%$ in total number of individuals. The number of species was high in spring and low in summer; number of individuals was high in spring and low in autumn. The diversity index (H') was 0.4-0.7 The abundance and species composition fluctuated seasonally. Occurrence of the various stages of fishes indicated that Scombia japonicus, T. japonicus and E japonicus utilized in the area as spawning ground, Conger myriaster larvae, Ammodytes personatus and Seriola quinqueradiata as nursery ground, and T. lepturus and Ilisha elongata as spawning and nursery grounds.

Tilt-rotor 항공기 동력계통 중량 추정에 대한 상쇄연구 (Trade-off Study of Propulsion Systems Weight Estimation for Tilt-rotor Personal Air Vehicle)

  • 이정훈
    • 항공우주시스템공학회지
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    • 제8권4호
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    • pp.1-6
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    • 2014
  • This paper presents the trade-off study of conducting a survey of the weights for various kind of propulsion systems installed in the Smart Unmanned Aerial Vehicle TR-100, a tilt-rotor vehicle, which is developed by Korea Aerospace Research Institute, in order to predict the appropriate propulsion system for present and future Personal Air Vehicle, which has single mode and vertical take-off & landing. In order to perform the trade-off study, we set the requirements that the vehicle hovers for 1 hour with 1,000 kg maximum take off weights. In this study, the power systems are classified engine, which uses the fossil fuel - turboshaft engine, piston engine, diesel engine and rotary engine, and electric motor with fuelcell or Li-Ion battery. The results of trade-off study shows the power systems using fossil fuel are superior to using fuelcell or Li-Ion battery for weight of propulsion system. Also turboshaft engine is the best power system for the aspects of system weight, and the nexts are rotary engine, piston engine, diesel engine, electric motor with Li-Ion battery, and electric motor with fuelcell.

분전반 관리시스템 평가를 위한 시험 장치의 제작 및 특성 분석 (Manufacturing and Characteristics Analysis of a Testing Device for the Evaluation of a Distribution Board Management System)

  • 고완수;이병설;최충석
    • 한국안전학회지
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    • 제34권5호
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    • pp.31-36
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    • 2019
  • This study made a testing device to evaluate the distribution board management system. Power was supplied to the testing device using a loading-back method and the voltage applied to it was 440 V at the same turn ratio. When the human body electric shock current is 30 mA, the breaking time is set to be less than 240 ms while 30~45 mA current is flowing. The test result shows that in the case of the R-phase it was measured to be 5.19 Hz (193 ms). And the S-phase and T-phase were perfectly cut off at 5.39 Hz (186 ms) and 5.71 Hz (175 ms), respectively. When the human body electric shock current is 60mA, the breaking time is set to be less than 120 ms while 45~75 mA current is flowing. The test result shows that the R-phase, S-phase, and T-phase were accurately cut off at 8.39 Hz (11 ms), 8.87Hz (113 ms) and 9.69 Hz (103 ms), respectively. When the human body electric shock current is 90 mA, the breaking time is set to be less than 48 ms while 75 mA current is flowing. The test result shows that the R-phase, S-phase, and T-phase were accurately cut off at 19.8 Hz (50.4 ms), 16.9 Hz (59.2 ms), and 17.9 Hz (56.0 ms), respectively. That is, the developed testing device satisfied all the requirements of the distribution board evaluation criteria, and it becomes available for the performance evaluation of the distribution board management system.

발목관절에 플로스밴드 적용이 기능적 관절가동범위와 보행능력에 미치는 영향 (Effects of Floss Band on Ankle Joint functional Range of Motion and gait ability)

  • 문병현;김지원
    • 한국융합학회논문지
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    • 제12권12호
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    • pp.419-425
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    • 2021
  • 본 연구의 목적은 건강한 성인을 대상으로 발목에 플로스밴드를 적용했을 때 발목의 기능적 관절가동범위와 보행능력에 미치는 효과를 검증하는 것이다. 총 20명이 실험에 참여했으며 무작위배정을 통해 발의 한쪽은 실험 측으로, 반대쪽은 대조 측으로 설정하였다. (중재 전, 후/ 실험 측과 대조 측) 두 가지 요인에 대해 분석하기 위하여 반복측정 이요인 분산분석 방법(two way-repated ANOVA)을 실시하였다. 유의수준은 0.05로 설정하였다. 연구결과 대조 측에 비하여 실험 측에서 WBLT와 발꿈치 딛기가 유의하게 증가하였다(p=.05). 중재 전, 후 검정에서 실험 측은 WBLT, 발꿈치 딛기, 발가락 떼기에서 유의한 증가를 보였다(p=.05). 대조 측은 발가락 떼기에서 유의한 증가를 보였다(p=.05). 따라서 본 연구에서 실시한 플로스밴드의 적용은 스포츠 및 재활 현장에서 기능적 관절가동범위를 증진시키고 보행능력을 향상시키는 데 도움을 줄 수 있을 것이다.

Ranked-Set Sample Wilcoxon Signed Rank Test For Quantiles Under Equal Allocation

  • Kim, Dong Hee;Kim, Hyun Gee
    • Communications for Statistical Applications and Methods
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    • 제10권2호
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    • pp.535-543
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    • 2003
  • A ranked set sample version of the sign test is proposed for testing hypotheses concerning the quantiles of a population characteristic by Kaur, et. al(2002). In this paper, we proposed the ranked set sample Wilcoxon signed rank test for quantiles under equal allocation. We obtain the asymptotic property and the asymptotic relative efficiencies of the proposed test statistic with respect to Wilcoxon signed rank test of simple random sample for quantiles under equal allocation. We calculate the ARE of test statistics, the proposed test statistic is more efficient than simple random sampling for all quantiles. The relative advantage of ranked set sampling is greatest at the median and tapers off in the tails.

Development of a sequence-characterized amplified region (SCAR) marker for female off-season flowering detection in date palm (Phoenix dactylifera L.)

  • Lalita Kethirun;Puangpaka Umpunjun;Ngarmnij Chuenboonngarm;Unchera Viboonjun
    • Journal of Plant Biotechnology
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    • 제50권
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    • pp.190-199
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    • 2023
  • Date palm (Phoenix dactylifera L.: Arecaceae) is a dioecious species where only female trees bear fruits. In their natural state, date palms produce dates once a year. However, in Thailand, some trees were observed to produce dates during the off-season, despite no variations in morphology. The availability of such off-season fruits can significantly increase their market value. Interestingly, most female off-season date palms investigated in this study were obtained through micropropagation. Hence, there is an urgent need for genetic markers to distinguish female offseason flowering plantlets within tissue culture systems. In this study, we aimed to develop random amplification of polymorphic DNA-sequence characterized amplified region (RAPD-SCAR) markers for the identification of female off-season flowering date palms cultivated in Thailand. A total of 160 random decamer primers were employed to screen for specific RAPD markers in off-season flowering male and female populations. Out of these, only one primer, OPN-02, generated distinct genomic DNA patterns in female off-season flowering (FOFdp) individuals compared to female seasonal flowering genotypes. Based on the RAPD-specific sequence, specific SCAR primers denoted as FOFdpF and FOFdpR were developed. These SCAR primers amplified a single 517-bp DNA fragment, predominantly found in off-season flowering populations, with an accuracy rate of 60%. These findings underscore the potential of SCAR marker technology for tracking offseason flowering in date palms. Notably, a BLAST analysis revealed a substantial similarity between the SCAR marker sequence and the transcript variant mRNA from Phoenix dactylifera encoding the SET DOMAIN GROUP 40 protein. In Arabidopsis, this protein is involved in the epigenetic regulation of flowering time. The genetic potential of the off-season flowering traits warrants further elucidation.

일일어획자료를 이용한 여수 해역의 정치망 어획물 종조성 (Species Composition Using the Daily Catch Data of a Set Net in the Coastal Waters off Yeosu, Korea)

  • 황선도;김진영;김주일;김성태;서영일;김종빈;김영혜;허선정
    • 한국어류학회지
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    • 제18권3호
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    • pp.223-233
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    • 2006
  • 2001년 4월부터 10월 사이에 돌산도 율림 앞바다, 2002년 4월부터 10월 사이에 연도 앞바다, 그리고 2003년 4월부터 12월 사이에 돌산도 임포 먼바다에서 정치망에 어획된 수산생물의 일일 어획자료를 이용하여 종조성과 양적 변동을 파악하고, 연도별, 장소간 종조성을 분석하였다. 2001~2003년에 여수 해역에서 정치망에 의해 삼치(Scomberomorus niphonius), 방어류 (Seriola spp.), 갈치(Trichiurus lepturus), 멸치 (Engraulis japonicus), 줄삼치(Sarda orientalis), 살오징어(Todarodes pacificus), 덕대(Pampus echinogaster), 밴댕이(Sardinella zunasi), 고등어(Scomber japonicus), 황아귀(Lophius litulon), 꼴뚜기(Loligo beka) 등이 양적으로 우세하게 어획되어 여수해역에서 정치망으로 어획된 어류의 종조성은 주로 표영성 어류가 대부분을 차지하였다. 연안역에서는 밴댕이, 덕대, 양태 (Platycephalus indicus), 꼴뚜기, 외해역에서는 삼치, 방어류, 갈치, 덕대, 살오징어, 검복(Takifugu porphyreus), 참돔(Pagrus major)의 표영성 주거종 (pelagic resident species)이 우세하였으며, 멸치는 남해 전체에서 계절적으로 연안과 외해를 이동하는 대표적인 우점종이었다. 봄에 연안에 밴댕이와 멸치가, 수심이 보다 깊은 외해에는 내유하는 멸치와 황아귀, 방어류 등 대상으로 어기가 시작되어 여름에 갈치, 삼치, 고등어, 방어류, 줄삼치, 덕대, 살오징어 등의 외양종이 연안과 외해에 회유하여 어획량이 높았다. 가을에는 연안에서 삼치, 멸치, 꼬치고기 (Sphyraena pinguis), 독가시치 (Siganus fuscescens), 주둥치 (Leiognathus nuchalis) 등이 우점하였고, 외해에서는 삼치, 덕대, 학공치(Hyporhamphus sajori), 고등어, 갈치 등이 여름에 이어 계속 출현하였으나 어획량은 감소하는 온대 해역의 전형적인 계절성을 보였다. 남해안에서 정치망에 어획된 출현종은 대부분 부어류이었으며 그 변화 정도가 심하였으나, 대형정치망 일일 어획자료은 부어류 종조성의 계절변동을 분석하는데 유의한 의미를 가질 것으로 판단된다.

조선시대 궁중의례행사의 차일의 기능과 특성에 관한 연구 -19세기 이후 궁중연향을 중심으로- (A Study on Functions and Characteristics of 'Cha-il(遮日)' through the Analysis of Ritual Events(宮中儀禮行事) in the Joseon Dynasty -Focused on the Congratulatory Events since 19C-)

  • 최지영;한동수
    • 건축역사연구
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    • 제14권2호
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    • pp.143-157
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    • 2005
  • This study aims to analyze functions and characteristics of 'Cha-il(遮日)' which was used at ritual events(宮中儀禮行事) in the Joseon dynasty, Joseon dynasty had many ritual events related with O-Rae(五禮). Cha-il was almost used at important ritual events, especially at the congratulatory events. The congratulatory events(宮中宴享) are the representative events were held with many temporary install facilities(假設施設) in a palace. Cha-il was a kind of Korean traditional membrane structures. Cha-il was set up for cutting off interior space from sunlight and rain. In general, Cha-il was Consisted of Cha-il-jang(遮日帳:woven fabric), Cha-il-jook(遮日竹:bamboo column), some ropes, and fixing wares. In the congratulatory events, three types of Cha-il. were set up. Baek-mok-Dae-Cha-il(白木大遮日)was made of cotton cloth. Yu-Dun-Cha-Il(油芚遮日) was made of oiled paper or oiled cotton cloth. Man-Joen-Cha-Il(滿箭遮日) consisted of wooden structure. Baek-mok-Dae-Cha-il(白木大遮日)was set up on the most important area of stage for protecting from sunlight. Yu-Dun-Cha-Il was set up on less important area of stage for protecting from sunlight and rain. Man-Joen-Cha-Il was set up below Baek-mok-Dae-Cha-il for supporting and draining raindrops off. The results of this study were as follows; Functions of Cha-il were to protect ritually space from sunlight and rain, and to extend ritually space, and to reconstruct ritually space. Cha-il was the peculiar temporary install facility which differed from other countries.

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