• Wind and Structures
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• 제8권5호
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• pp.357-372
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• 2005

Mean and extreme pressure distributions on a large cantilevered flat roof model are measured in a boundary layer wind tunnel. The largest peak suction values are observed from pressure taps beneath conical "delta-wing type" corner vortices that occur for oblique winds, then the characteristics and causes of the local peak suctions are discussed in detail. Power spectra of fluctuating wind pressures measured from some typical taps located at the roof edges under different wind directions are presented, and coherence functions of fluctuating pressures are also obtained. Based on these results, it is verified that the peak suctions are highly correlated with the conical vortices. Furthermore, according to the characteristics of wind loads on the roof, an aerodynamic solution to minimize the peak suctions by venting the leading edges and the corners of the roof is recommended. The experimental results show that the suggested strategy can effectively control the generation of the conical vortices and make a reduction of 50% in mean pressures and 25% in extreme local pressures at wind sensitive locations on the roof.

• 대한기계학회논문집B
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• 제25권3호
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• pp.381-388
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• 2001

Presented are heat data which describe the effect of interaction between bulk flow pulsations and a vortex embedded in a turbulent boundary layer. The pulsation frequencies are 3 Hz, 15 Hz and 30 Hz. A half delta wing with the same height as the boundary layer thickness is used to generate the vortex flow. The convection heat transfer coefficients on a constant heat-flux surface are measured by embedded 77 T-type thermocouples. Spanwise profiles of convection heat transfer coefficients show that upwash region of vortex flow is influenced by bulk flow pulsations. The local heat transfer coefficient increases approximately by 7 percent. The increase in the local change of convection heat transfer coefficient is attributed to the spanwise oscillatory motion of vortex flow especially at the low Strouhal number and to the periodic change of vortex size.

• 한국자원식물학회지
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• 제20권6호
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• pp.491-498
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• 2007

It has been hypothesized that efficient exclusion of methylated retrotransposons and repeated DNA region is one of the rapid and cost-effective approaches for comprehensive gene discovery in large genome size of maize. Three kinds of methylation-sensitive restriction enzymes, HapII, MspI and McrBC, were used to identify the restriction frequency of cytosine methylation sites in maize genome. Roughly 60% of total maize genomic DNA was restricted less than 500bp by McrBC, and the most of restricted small size fraction was composed retrotransposon. In order to validate the efficient construction of gene-rich shotgun library, we compare two gene-rich methyl-filtration shotgun libraries using in vivo and in vitro methyl-filtration system. The size selected DNA fraction by Sau3A-McrBC enzyme treated was very stable and has not appeared modification in E. coli, but most insert DNA size of partially digested with Sau3A were decrease less than 500bp by bacterial methylation-modification system. In compare of retroelements portion, A 44.6% of the sequences were retroelement in unmethyl-filtered library, and the most of them was Copia type, such as Prem, Opie and Ji. The portion of retroelement was drastically decreased to 25% and 20% by in vivo and in vitro filtration system, respectively.

• 건축역사연구
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• 제16권1호
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• pp.69-82
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• 2007

[ $\sqcap$ ]' shape of Jeonnam Area has not been well-known so far. This study is about when, how and on what type the '$\sqcap$' shape had settled among many 'ㅡ' shape houses. The Anchae of Jeonnam Area which appeared 17C. contrasts with 'ㅡ' shape. Especially, the head family's house might have been expected to develop with special difference. 'ㅡ' shape had been built much more than the '$\sqcap$' shape around 20C when modernization had been ripen. It was big event that '$\sqcap$' shape, the head family's house, had been pulled down and then 'ㅡ' shape had been newly built. (Ui Seong-ryeol house) The reason why 'ㅡ' shape had been built instead of '$\sqcap$' shape might be that people accepted the change of 'modernization', that is to say, people accepted convenience and opening. The plan of '$\sqcap$' shape consists of Daecheong and Anbang at the center of Momche, and Jageunbang and Jangji at both sides. In the '$\sqcap$' shape, the center of Momche is wide dand light unlike 'ㅡ' shape. Unjoru, Nogudang, Yundoseo house have long wing and have more encircling Anmadang than other houses, which are well known for a house for a man of noble birth.

• 항공우주기술
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• 제10권2호
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• pp.146-153
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• 2011

복합재 항공기의 설계하중 데이터로부터 전기체 구조시험 중에 하중부가용 스트랩에 부가될 시험하중의 크기를 산출하는 몇 가지 방법에 대하여 비교 분석하였다. 이 방법들을 KC-100 복합재 항공기 좌측 주익의 시험하중 산출과정에 적용해보고 산출된 결과의 특성 및 차이를 분석하였다. 항공기 전기체 구조시험에 부가되는 시험하중은 각 항공기의 설계 하중의 특성 및 하중부가용 스트랩의 위치 등에 따라 그 크기가 다르게 결정되므로 본 연구에서 소개하는 시험하중 산출방법을 모두 적용하여 결과를 비교해보고 최종적으로 적합한 방법을 선정하는 과정이 필요하다.

• 한국추진공학회지
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• 제17권4호
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• pp.49-55
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• 2013

한국항공우주연구원 (이하 항우연)에서 개발중인 중형 전기동력 무인기 EAV2의 추진시스템에 대한 비행시험결과에 대하여 기술 하였다. EAV2는 날개 길이 6.9 m, 무게 18 kg의 저속 장기 체공형 무인기이다. 전기 동력원으로는 태양전지, 연료전지, 배터리의 세 가지를 동시에 사용한다. EAV2는 2012년 6월에 22시간 이상 체공 비행에 성공하였다. 시험 결과, 전기추진 시스템은 비행 중 일어나는 여러 상황에서 필요한 동력을 성공적으로 공급하였으며, 각 동력원들은 설계된 목적에 부합하게 작동되었다.

• 상하수도학회지
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• 제32권6호
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• pp.573-581
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• 2018

The purpose of this study is to evaluate the fixed wing type domestic UAV for monitoring of algae bloom in aquatic environment. The UAV used in this study is operated automatically in-flight using an automatic navigation device, and flies along a path targeting preconfigured GPS coordinates of desired measurement sites input by a flight path controller. The sensors used in this study were Sequoia multi-spectral cameras. The photographed images were processed using orthomosaics, georeferenced digital surface models, and 3D mapping software such as Pix4D. In this study, NDVI(Normalized distribution vegetation index) was used for estimating the concentration of chlorophyll-a in river. Based on the NDVI analysis, the distribution areas of chlorophyll-a could be analyzed. The UAV image was compared with a airborne image at a similar time and place. UAV images were found to be effective for monitoring of chlorophyll-a in river.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.255-262
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• 2021

The paper examines the influence of ownership type on environmental performance of Chinese listed enterprises. China's environmental problems are attributed to the collusion between enterprises and economy-oriented local governments, which has allowed many companies to skirt environmental regulations. Especially, local state-owned enterprises (SOEs) tend to have worse environmental performance than private firms, under the wing of local governments, with whom they have a closer political connection. According to the report of the Environmental Protection Agency, currently the unacceptably poor environmental performance of local SOEs has severely hampered the realization of green economy in China. After examining the dataset of 15,996 firm-year observations from 2,688 listed firms, this paper found that, in the presence of central government supervision and personnel intervention, listed local SOEs will be forced to improve their environmental performance in accordance with standards set by the central government, which leads to better environmental performance than that of listed private firms (private firms). The result of two-stage regression also supports the conclusion. This shows increased supervision and personnel intervention from the central government can significantly improve the environmental performance of local SOEs. The research in this paper expects to make a contribution to attaining the goal of green economy in China.

• 항공우주시스템공학회지
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• 제15권1호
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• pp.40-46
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• 2021

본 연구에서는 재난치안무인기 MC-1,2,3 대비 임무능력이 대폭 향상된 임무확장형 무인기 후보인 틸트로터 무인기의 공력형상설계와 성능향상을 위한 연구를 수행하였다. 기존 운영 중인 TR60 틸트로터 무인기의 형상을 근간으로 성능향상을 위하여 동체 및 꼬리날개 형상을 개선하고 나셀에 확장날개를 장착한 새로운 TR5X 개념형상을 설계하고 전산유체해석을 통해 기존 TR60과 공력성능을 비교하였다. 또한 TR5X 전기체 공력데이터를 구축하고 전기체 비행성능해석을 수행하여 목표로 설정된 주요 성능요구도가 만족됨을 확인하였다.

• 식물분류학회지
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• 제52권4호
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• pp.207-213
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• 2022

An effective pollinator was investigated based on visiting insects to confirm the pollination mechanism of Impatiens furcillata Hemsl. (cheo-jin-mul-bong-seon), an annual herb that is also a species endemic to Korea that has hardly been studied in relation to pollination ecology. The insects that visited the group of I. furcillata studied here consisted of four orders, 11 families, and 16 species; Hymenoptera had seven species (43.8%), Lepidoptera had four (25.0%), Diptera four (25.0%), and Hemiptera one (6.2%). Visiting insects were divided into those that took only nectar, those that took nectar and pollen, and those that took neither. Insects that are effective for pollination are judged considering the length and body type of their mouth parts, and Amegilla florea Smith (huin-jul-beol) is judged to be the most effective pollinator in the survey area. As a result of observing pollination behavior, when visiting a flower, A. florea, which extended its glossa, approached the front, landed on a wing petal of I. furcillata, crawled into the flower tube, and then backed up and reversed its steps, with pollen adhered to its back. The findings here present basic information about species biology related to both I. furcillata and A. florea.