• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.1437-1441
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• 2009

기존의 ADCP는 1m 이하의 저수심 지점에서 측정이 불가능하였으며, 유속계 측정장비는 저유속 지점에서 측정이 불가능한 경우가 많아 유량측정에 어려움을 겪는 경우가 많다. 최근 RDInstruments에서 제작한 StreamPro는 1m 이하의 수심, 0.1m/s 이하의 유속에서 측정이 가능하기 때문에 이를 이용하면 저수심, 저유속 지점에서 유량측정이 가능하다. ADCP를 이용한 측정의 경우 보다 정확한 측정성과를 얻기 위하여 유속의 50% 속도로 이동하며 측정하여야 하며, 4회 측정유량값의 상대오차가 5% 이내일 때 그 평균값을 측정치로 한다. 그러나 0.1m/s 이하의 유속이 나타나는 지점은 0.05m/s 이하의 속도로 이동하며 측정을 실시하여야 하며 이 경우 측정시간이 너무 길어지는 문제가 있다. 따라서 본 연구에서는 StreamPro를 이용한 유량측정의 적용성 평가와 함께 적절한 신뢰도를 얻을 수 있는 실용적인 측정회수 분석을 실시하였다. StreamPro를 이용한 측정성과의 적용성을 평가하기 위하여 StreamPro와 동시에 Price 유속계 측정을 실시하여 이를 비교하였다. 실용적인 적정 측정회수 분석은 측정유량의 상대오차를 Student-t분포에 적용하여 불확실도값을 기준으로 분석하였다. StreamPro와 Price 유속계 측정성과를 비교한 결과, 평균 상대오차가 약 3.5%로 적절한 값을 나타냈으며, 저수심, 저유속 지점에서의 실용적인 측정회수는 약 11회로 나타났다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.277-281
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• 2006

A study on stream-groundwater exchange was performed using head and temperature data of stream water, streambed, and groundwater. Groundwater level and temperature were obtained from multi-depth monitoring wells in small-scale watershed. In the summer time, time series of temperatrue data at streambed and groundwater were monitored for three months. In the winter time, we measured the temperature gradient between stream water and streambed. The observed data showed three typical types of temperature characteristics. First, the temperature of streambed was lower than that of stream water; second, the temperature of streambed and stream water was similar; and last, the temperature of streambed was higher than that of stream water. The interconnections between the stream and the streambed were not homogeneously distributed due to weakly developed sediments and heterogeneous bedrock exposed as bed of the stream. The temperature data may be used in formal solutions of the inverse problems to estimate groundwater flow and hydraulic conductivity.

• 환경영향평가
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• 제14권1호
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• pp.37-46
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• 2005

In this study, field surveys were performed for 12 stations in main stream of Hongjechun and 3 stations in 2 tributaries, respectively, in order to find out dried reaches of the stream, and to examine the water quality of the stream, and to suggest methods to improve the stream concerned into eco-stream. In the results of water quality in stream, however distinct difference for seasonal variation of the water quality was not found, the water quality of winter was relatively better than that of other seasons. Annual mean concentration of BOD was 6.5mg/L in the upper reach, 11.8mg/L in the middle reach, 15.3mg/L in the lower reach of main stream, and total mean was 12.5mg/L, while the BOD concentration was 3.6mg/L in the upper reach, and was 9.6mg/L in the low reach of Gukichun, the tributary. Based on flow examination, the level of water depth was so low and the flow can not be traveled downstream in the reach between ST-9 and ST-10 for low water season, whereas it was observed that the flow was traveling except the dry season even the water level was lower than that of adjacent stations.

• 물과 미래
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• 제28권3호
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• pp.197-204
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• 1995

인구의 도시집중으로 인하여 유역의 유출용적이 증대하며 이로 인한 합류부의 수위상승으로 내수배제가 불가능하게 되어 침수피해가 발생하고 있다. 본 실험연구에서는 소유역 하천에서 우수거의 합류로 인한 본류하천의 흐름변화를 실험하였으며, 하천의 수위상승을 소하천(본류)의 유량과 경사, 우수거(지류)의 유량과 경사 및 합류각에 따른 본류의 수위상승을 분석하였다. 실험결과 본류하천의 경사에 대해서는 경사가 급할수록 수심비가 증대하는 것으로 나타났으며, 본류의 유량은 적을수록, 지류의 유량은 많을 수록 수심비는 크게 나타났다. 합류각에 대해서는 합류각이 작을수록 수심비가 작은값을 나타내고 있다. 이와 같이 도시 소하천의 합류시 수심비의 상승영향을 보면 합류각, 지류유량 및 본류유량 등의 순으로 상승영향이 밀접하게 나타났다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.4108-4125
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• 2015

This paper presents a scalable coding method for depth images by considering the quality of synthesized images in virtual views. First, we design a new edge detection algorithm that is based on calculating the depth difference between two neighboring pixels within the depth map. By choosing different thresholds, this algorithm generates a scalable bit stream that puts larger depth differences in front, followed by smaller depth differences. A scalable scheme is also designed for coding depth pixels through a layered sampling structure. At the receiver side, the full-resolution depth image is reconstructed from the received bits by solving a partial-differential-equation (PDE). Experimental results show that the proposed method improves the rate-distortion performance of synthesized images at virtual views and achieves better visual quality.

• 한국환경복원기술학회지
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• 제6권6호
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• pp.49-55
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• 2003

Total phosphorous removal rate was examined of a subsurface-flow treatment wetland system which was constructed on floodplain in the down reach of the Kwangju Stream in Korea from May to June 2001. Its dimensions were 29 meter in length, 9 meter in width and 0.65 meter in depth. A bottom layer of 45 cm in depth was filled with crushed granite with about 15~30 mm in diameter and a middle layer of 10 cm in depth had pea pebbles with about 10 mm in diameter. An upper layer of 5 cm in depth contained course sand. Reeds(Phragmites australis) were transplanted on the surface of the system. They were dug out of natural wetlands and stems were cut at about 40 cm height from their bottom ends. Water of the Kwangju Stream flowed from a submerged dam into it via a pipe by gravity flow and treated effluent was funneled back into the Stream. The number of reed stems increased from 80 stems/$m^2$ in July 2001 to 136 stems/$m^2$ in September 2001. The hight of stems was 44.2 cm in July 2001 and 75.3 cm in September 2001. The establishment of reeds at early operating stage of the system was good. Volume and water quality of inflow and outflow were investigated from July 2001 through December 2001. The average inflow was 40 $m^3$/day and hydraulic detention time was about 1.5 days. The concentration of total phosphorous n influent and effluent was 0.83 and 0.33 mg/L, respectively. The removal rate of total phosphorous averaged about 60%. The removal efficiency was slightly higher, compared with that of subsurface-flow wetlands operating in North America, whose retention rate of total phosphorous was reported to be about 56%. The good abatement rate could be attributed to sedimentation of particle phosphorous in pores of the media and adsorption of phosphorous to the biofilm developed on the surface of them. Increase of standing density of reeds within a few years will develop root zones which may lead to increment in the phosphorous retention rate.

• Ecology and Resilient Infrastructure
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• 제1권2호
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• pp.49-60
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• 2014

본 연구는 전형적인 자갈하천인 가평천에서 하천 환경과 서식처 교란이 어류 군집구조에 미치는 영향을 파악하기 위하여, 13개 조사지점에서 미국 환경청의 간편 생물평가법을 적용하여 하천환경을 평가하고 어류 군집구조를 조사하였다. 하천환경 평가 자료를 이용하여 주요인분석을 실시한 결과, 하상 경사와 관계가 있는 하상 서식환경, 유속/수심 체제, 유사 퇴적이 주요한 평가항목으로 판별되었다. 가평천에서 출현한 어종은 12과 46종이었고, 우점종이 참갈겨니 (Zacco koreanus), 아우점종이 피라미 (Z. platypus)이었다. 종별 개체수 자료를 사용하여 계층적 군집분석의 결과, 조사지는 상류, 중류 및 하류의 세 개의 집단으로 구분되었다. 비모수다차원척도법 결과에 의하면, 어류는 하천환경 평가 항목 중 하상 서식환경, 하상 매몰, 유속/수심 체제, 유사 퇴적, 하도 개수, 여울 빈도 항목과 유의한 상관관계가 있었다. 따라서 자갈하천인 가평천에서 어류 군집구조는 일차적으로 하상의 종적 환경 변화에 의하여 영향을 받고, 인위적 교란에 의하여 군집구조에 변화가 나타났다.

• Journal of Ecology and Environment
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• 제34권2호
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• pp.175-191
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• 2011

Colonization patterns and community changes in benthic macroinvertebrates in the Cheonggye Stream, a functionally restored stream in downtown Seoul, Korea, were studied from November 2005 to November 2007. Benthic macroinvertebrates were quantitatively sampled 15 times from five sites in the stream section. Taxa richness (59 species in total) increased gradually over the first year, whereas the density revealed seasonal differences with significantly lower values in the winter season and after flood events. The benthic macroinvertebrate fauna may have drifted from the upstream reaches during floods and from the Han River, arrived aerially, or hitchhiked on artificially planted aquatic plants. Oligochaeta, Chironommidae, Psychodidae, and Hydropsychidae were identified as major community structure contributors in the stream. Swimmers and clingers colonized relatively earlier in the upper and middle reaches, whereas burrowers dominated particularly in the lower reaches. Collector-gatherers colonized at a relatively early period throughout the stream reaches, and collector-filterers, such as the net-spinning caddisfly (Cheumatopyche brevilineata), predominated in the upper and middle reaches after a 1-year time period. Cluster analyses and multi-response permutation procedures demonstrated that the Cheonggye Stream shares more similarities with the Jungnang Stream than with the Gapyeong Stream. Detrended correspondence analysis and nonmetric multidimensional scaling demonstrated that physical environmental factors (depth, current velocity, dissolved oxygen, and pH) as well as nutrients (total nitrogen and total phosphorous), water temperature, and conductivity could affect the distribution of benthic macroinvertebrates in the study streams.

• The Korean Journal of Ecology
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• 제28권6호
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• pp.365-373
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• 2005

Understanding the relation of water environmental factors and vegetation is critical to restoration and management of wetlands. To reveal relationships between representative plant groups and water environments, we measured cover and abundance of plant species, water depth, temperature, pH, conductivity, dissolved oxygen, $NH_4$-N, $NO_3$-N, and $PO_4-P$ concentration in water in Wangsuk stream (WS) and Gwarim reservoir (GR). This study was conducted monthly from May to October, 2004. Six vegetation groups $(W1{\sim}W6)$ in WS and five vegetation groups $(G1{\sim}G5)$ in GR were identified using TWINSPAN. WS was characterized by Phragmites japonica, Digitaria sanguinalis, Phalaris arundinacea, Beckmannia xyzigachne and Persicara hydropiper, Persicaria thunbergii, Typha angustifolia. GR was characterized by T. angustifolia, Scirpus tabernaemontani, P. thunbergii, Humulus japonicus and Scirpus fluviatilis, Typha orientalis, Zizania latifolia. The vegetation in WS experienced greater seasonal changes than in GR. A correspondence analysis suggests that water depth was the major environmental factor influencing the distribution of most plants communities in both wetlands.

• 정보보호학회논문지
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• 제11권1호
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• pp.3-12
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• 2001

본 논문은 무선채널에서 안전한 암호통신을 위해 동기식 스트림 암호시스템을 설계하였다 페이딩 채널에서 설계된 스트립 암호를 통해 암호문을 전송할 때 한 주기 동안 발생하는 동기패턴, 세션키, 암호문 정보에 적합한 인터리빙 기 법을 설계하여 전송함으로써 버스트 오류로부터 암호문을 보호하고 전송성능을 개선하여 robust한 암호통신을 가능하도록 하였다. 본 논문에서는 동적인 인터리빙 depth를 갖는 DAA를 적용함으로써 정적인 인터리빙 depth를 갖는 SAA (static allocation algorithm)보다 전송성능 개선을 얻었다.