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치어의 먹이선호도 및 포식이 낙동강 동물플랑크톤군집에 미치는 영향
장광현 ( Jang Gwang Hyeon ),김현우 ( Kim Hyeon U ),라긍환 ( La Geung Hwan ),정광석 ( Jeong Gwang Seog ),주기재 ( Ju Gi Jae ) 한국하천호수학회 2004 생태와 환경 Vol.37 No.1
In the present study, pre preference of juvennile fishes was examined using as experimental approach. Zooplankton composition, as a prey of thr fish, was evaluated by taking into account the species as well as body size of juveniles in the aquqrium. The redation of juvenile fishes is known to be an important factor in changes of zooplankton communities. in some previous studies at the regulated Nakdong River, the collapse of large cladcoerans and an increase in the rotifer population by selective predation during spring and summer were observed. This study focused on the predation of juvenile fisheds such as Hyporhamphus sajori, Rhinogobius brunneus, and Opsariichtys uncirostris amurensis on zooplankton community structure in mesocosm scale experiments. These fishes selected the cladoceran Monia micrura with highest individual preference value(Manly.Chesson index) among zooplankton prey in the experimental aquarium. Whrn the size-selective prey prefernces of the juvenile fish were compared, both small (body size<2㎝)and large(body size>2㎝) juveniles of O. uncirostris positively selected M. micrura. in the outdoor experimental tanks, juvenile fishes consuumed the cladoceran M. micrura, resulting in an igh abundance of the rotifer, Polyarthra spp. The results suggest that juvenile fish predation may play an important role in regulating the zooplankton community structure by reducing the cladoceran density and increase of rotifers in the Nakdong River during spring and summer.
Computed Radiography 환경에서의 REPEAT 유형변화에 대한 고찰
안미섭,장광현,문희석,정환,An, Mi-Seop,Jang, Gwang-Hyeon,Mun, Hui-Seok,Jeong, Hwan 대한디지털의료영상학회 1997 대한디지털의료영상학회논문지 Vol.3 No.1
Before entering 21st Century, modern medical science is requiring more precise display which is highly estimated in diagnostic value as radial science technology is achieving sharp development. And it is also trying to contribute to improve national health and to offer better service by reducing radial exposure. General projection and Fluoroscopy which are most difficult to be displayed in digital tend to change their way ; from analog to digital with development of Electronic Engineering and Computer Technology, Introducing to CR system in 1994, SMC have displayed General projection and Fluoroscopy 100% in digital using CR system. This study searched differences between repeat rate, repeat type in the exam using Film/Screen and those in the exam using CR system. According to the analysis of repeat types and repeat rate of Film which was reused by using CR system in general projection room and Fluoroscopy room of SMC, we found that total 192,813 films were used and 2,097 films, 1.09% of total were reused. However, actual repeat covers 0.76% to 1,461 sheets with the exception of 636sheets. As above, display process using CR system is 0.76% much lower than general repeat rate 2$\sim$4% of Film/Screen exam. Besides decreased under/over exposure, it is appeared that position failure rate in repeat rate 0.76% covers relatively high 31%. Noticing that repeat caused unskilled devices handing was found many times, sufficient understanding seems to be required to reduce repeat.
강-저수지 복합형 시스템내 봄 동물플랑크톤의 역동성 (낙동강, 한국): 식물플랑크톤 생체량 조절자로서의 역할
김현우 ( Kim Hyeon U ),장광현 ( Jang Gwang Hyeon ),정광석 ( Jeong Gwang Seog ),주기재 ( Ju Gi Jae ) 한국하천호수학회 2003 생태와 환경 Vol.36 No.4
During a three-year study (2000-2002), dramatic changes in the phytoplankton biomass and high transparency were repeatedly observed during mid-spring in the lower part of the Nakdong River. Rotifers(Branchonus, Keratella, Polyarthra), sharply increased (to near 20 days) and water temperature increased from 10℃ to > 20℃ toward the end of springm small cladocerans noticeably increased. Once phytoplankton biomass passed their peak stage in the min-spring, a short period (one or two weeks) of relatively low phytoplankton biomass and high Secchi transparencies occurred. Grazing by the zooplankton was highest in spring, thus, it seems that high grazing activities of zooplankton grazing regulated phytoplankton dynamics in the river. The results indicate that the role of zooplankton grazing in controlling the phytoplankton biomass becomes more important during the spring when river water is relatively stagnant.
간헐식 흐름방식을 활용한 수직 · 수평 습지의 정화효율 평가
주광진(Kwang Jin Joo),이동민(Dong Min Lee),김기중(Ki Jung Kim),조용철(Yong Chul Cho),장광현(Gwang Hyeon Jang),최이송(I Song Choi),오종민(Jong Min Oh) 응용생태공학회 2017 Ecology and resilient infrastructure Vol.4 No.3
본 연구에서는 부영양화의 원인이 되는 질소와 인의 제거 효율을 향상시킬 목적으로 광물질을 활용한 여재를 이용하여 호기, 혐기의 흐름조건을 만들어주기 위한 수직·수평 흐름 인공습지를 고안하여 아크릴 반응조로 제작한 후 성능평가를 진행하였다. 수직·수평 흐름형 인공습지의 경우 호기 및 혐기조건을 평가하기 위해서 반응조 내 용존산소(DO) 농도를 측정해본 결과 호기상태에서는 2.7 ㎎/L, 혐기상태에서는 N.D로 확인되어 목적에 부합된 결과가 확인되었다. 실험결과에서는 SS 저감효과가 140 min, 80 min, 60 min의 운전시간에서 각각 94%, 91%, 61%의 효율을 보였고, T-P의 경우 각각의 운전시간에 따라 84%, 71%, 63%의 저감효율을 보였다. 또한 T-N의 경우 각각의 운전시간에 따라 63%, 49%, 42%의 저감효율을 보여 기존의 습지가 12~24 hr 체류시간을 가지는 것에 비하여 짧은 운전시간에도 높은 처리효율을 보이는 것으로 확인되었다. 본 연구에서는 수직·수평 흐름 방식을 복합 적용하여 기존 인공습지의 단점을 보완하기 위해 기술개발을 진행한 것으로 어떠한 기능적 효과를 갖는지 확인하였고, 향후 이에 대한 현장적용을 위한 운영 및 관리적 차원의 메커니즘 연구가 추가로 진행 될 필요가 있다. Nitrogen and phosphorus are key factors in causing eutrophication of water body. In this study, ceramics media was selected to increase the removal efficiency of nitrogen and phosphorus. We designed vertical, horizontal flow constructed wetlands to create aerobic and anaerobic flow conditions by using the media, then proceeded to performance evaluations after acrylic reactors were produced. In the case of vertical and horizontal flow constructed wetlands, we measured oxygen concentrations to evaluate aerobic and anaerobic conditions. we got the result of 2.7 ㎎/L in the aerobic condition, N.D in the anaerobic condition respectively, which suited our purpose. The result of the combined vertical and horizontal flow condition showed that the removal efficiency of SS was 94%, 91%, 61% at 140 min, 80 min, 60 min of running times, respectively, and the removal efficiency of T-P was 84%, 71%, 63% during each running time. In case of T-N, the removal efficiency was 63%, 49%, 42% during each running time. We found that the reactor exerted better removal efficiency when in the short time compared to 12 - 24 hr residence time of existing wetlands. In this study, we conducted experiments to explore functional effects after applying combined vertical and horizontal flow methods in the field. Further study will be carried out to identify its mechanism and administrative perspective.
김지아 ( Ji Ah Kim ),김병준 ( Byeong Jun Kim ),김태훈 ( Tae Hoon Kim ),김원재 ( Won Jae Kim ),장광현 ( Gwang Hyeon Jang ),오종민 ( Jong Min Oh ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.1
Filter media have been used for various purposes such as water treatment facilities and methods. The purpose of this study is to evaluate and analyze the filter media chosen by their compositions. The subjects of the filtration experiments were zeolite, volcanic rock, foam glass and polyethylene. Zeolite and volcanic rock are sort of minerals that have specific characteristics. Foam glass contains void volume because it is made by foaming processes. Polyethylene is high molecular compounds. The results of experiments, the removal efficiency of SS is highest for foam glass showing 78.1%. COD and T-N removal efficiency is highest for zeolites showing 53.8% and 64.0%. The removal efficiency of T-P is highest for volcanic rocks showing 22%. In conclusion, selecting appropriate filter media based on the consideration of their characteristics is requested when applying water purification technology and water treatment facility with filter media.