• 대한토목학회논문집
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• 제12권3호
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• pp.173-180
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• 1992

자연 하천의 전형적인 특성인 하도사행으로 인한 만곡부의 수리 및 계량형태학적 특성을 확정론적 방법으로 구명하였다. 새로운 특성인자로 단변형상계수(As)을 제안했으며 하도구간에서의 As의 변화는 모든 유로에서의 수류력의 집중위치를 확인시켜주고 만곡의 영향이 단면형상의 변화에 미치는 영향을 정량적으로 보여주었다. 또한 기존의 사행특성인자와의 상관분석을 통하여 적용성을 입증하였다. 곡률비 R/W이 2-4에 집중되어있고 이는 제방의 침식이나 파제의 가능성이 있음을 보여주는 수치임을 알수있고 횡단면 하상의 변화를 예측할수있는 Bendegom의 식이 본 연구대상 하천에도 적용될수 있음을 밝혔다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.1335-1339
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• 2004

A hydro-geomorphologic change in a sand bed channel reach and vegetation expansion by changes in the How regime is analyzed in this study. Field and aerial photo surveys, basic hydrological analysis about flow regime change due to two dams, Andong Dam and Imha Dam, on the upstream river and computer modeling are conducted. Two Dams in the study reach have obviously affected downstream channel in many ways including the bed particle coarsening, vegetation expansion on the sandbars and following river channel braiding. The phenomenon of no vegetation on the large point bar in front of Hahwe Village seems due to disturbance of the sandbar surface probably due to the cross flow in the meander reach during the flood. Another reason for no vegetation is that the sandbar on this reach has lower subsurface water lovels, as compared with the others in the up- and downstream of the reach where vegetation expanded, which would hinder vegetation from germinating and growing on the sandbar.

• 대한토목학회논문집
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• 제11권4호
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• pp.81-89
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• 1991

사행하천형의 특성은 유로의 한쪽제방을 침식시키고, 다른 쪽은 퇴적을 일으키므로써 유로위치에 따라 천천히 형성되는데, 본 연구에서는 Odgaard(1986)가 제안한 횡방향 하상경사에 관한 선형 2차 미분방정식에 Langbein & Leopold(1966)가 제안한 sine-generated curve를 도입하므로써 위상차 및 폭-수심비의 영향을 고려한 새로운 하상형을 제시하고, 금강유역에 위치한 청원과 연기지역을 대상하천으로 하상변동조사보고서의 자료를 이용하여 비교분석한 결과 실측치와 잘 일치하였다.

• 한국환경생태학회지
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• 제25권1호
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• pp.71-80
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• 2011

2009년 8월부터 2010년 4월까지 탄천 9개 미소서식지에서 어류상과 피라미 개체군의 특성을 조사하였다. 조사 기간동안 채집된 어류는 총 7과 17종개체가 확인되었다. 출현한 어종 중 한국고유종은 Hemiculter eigenmanni와 Odontobutis interrupta로 2종(11.8%)이었으며 국외도입종은 Microterus salmoides 1종 이었다. 우점종으로는 Zacco platypus, 아우점종으로는 Carassius auratus 이었다. 서식처별로는 댐형 웅덩이, 사행형 웅덩이, 평여울, 거석형 웅덩이 등에서 Carassius auratus가 우점하였고, Pseudogobio esocinus는 샛강, Rhinogobius brunneus는 급여울, Z. platypus 는 개방형 하도습지, 낙차형 웅덩이, 폐쇄형 웅덩이 등에서 우점하였다. Z. platypus의 성장도와 비만도의 회귀계수 b값이 3.29의 값으로 나타났고 PCA 분석 결과 탄천에서 크게 3개의 Group으로 나누어졌다. 탄천의 서식처 별 Bray-Curtis Cluster 분석을 실시한 결과 낙차형 웅덩이와 폐쇄형 하도습지가 65.9%로 가장 유사한 것으로 나타났으며, 30.4%로 댐형 웅덩이와 급여울이 가장 대조적인 것으로 확인되었다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.799-802
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• 2008

General behaviors based on hydraulic characteristics of natural streams and channels have been recently analyzed and developed via various numerical models. However in the states of natural hydraulics, an experimental research must be performed simultaneously with the mathematical analysis due to effects of hydraulic properties such as meander, sediment, and so on. In this study based on 2-D advection-dispersion equation, flow and tracer experiments were performed in the S-curved meandering laboratory channel with a rectangular cross-section. The channel was equipped with instrument carriages which was equipped with an auto-traversing system to be used with velocity measuring sensors throughout the depth and breadth of the flow field. To measure concentration distribution of the salt solution was adjusted to that of the flume water by adding methanol and a red dye (KMnO4) was added to aid the visualization of the tracer cloud, the tracer was instantaneously injected into the flow as a full-depth vertical line source by the instantaneous injector and the initial concentration of the tracer was 100,000 mg/l. The secondary current as well as the primary flow pattern was analyzed to investigate the flow distribution in the meandering channels. The velocity distribution of the primary flow for all cases skewed toward the inner bank at the first bend, and was almost symmetric at the crossovers, and then shifted toward the inner bank again at the next alternating bend. Thus, one can clearly notice that the maximum velocity occurs taking the shortest course along the channel, irrespective of the flow conditions. The result of the tracer tests shows that pollutant clouds are spreading following the maximum velocity lines in each cases with various mixing patterns like superposition, separation, and stagnation of pollutant clouds. Flow characteristics in each cases performed in this study can be compared with tracer dispersion characteristics with using evaluation of longitudinal and transverse dispersion coefficients(LDC, TDC). As expected, LDC and TDC in meandering parts have been evaluated with increasing distribution and straight parts have effected to evaluate minimum of LDC and TDC due to symmetric flow patterns and attenuations of secondary flow.

• International journal of advanced smart convergence
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• 제1권1호
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• pp.1-5
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• 2012

We propose a structure for a multiple input multiple output antenna which has no space for isolation. The antenna operates in a frequency range of 2.4-2.48 GHz and can achieve a high channel capability as a Bluetooth antenna. The MIMO antenna consists of two planar inverted F antennas with symmetric structure. We designed the proposed antenna using HFSS simulator, and we designed the fabricated antenna using PCB fabricator. The MIMO antenna's isolation $S_{21}{\leq}-10dB$ and reflection coefficient $S_{11}{\leq}-20dB$. The proposed antenna's specification satisfies Bluetooth antenna's criteria and has more space than the existing MIMO antennas, which have space for isolation.

• Water Engineering Research
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• 제2권1호
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• pp.33-48
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• 2001

For the design of suitable aquatic habitats and habitat management purposes, sensitive descriptors for aquatic areas were identified and analyzed. The classification system of the aquatic areas were developed for natural streams and modified streams in Korea. Relationships among the descriptors of an aquatic area such as channel width, meander wave length, and arc angle have been defined. The analysis indicates that the total mean sinuosity is 1.25 for the main channels of natural streams, whereas the mean value of the sinuosity of modified streams is 1.14. The mean values of the total area, the width, and the length for the sandbars of natural streams are larger than those of modified streams.

• 한국지역지리학회지
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• 제14권4호
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• pp.279-289
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• 2008

본 연구에서는 고령군에 산재하는 지형경관자원을 발굴하여, 그 분포를 지도화 함으로써 지형경관자원의 관리에 기반이 되는 자료를 제공하고, 이를 활용하는 방안을 제시하고자 하였다. 분석결과는 다음과 같다. 첫째, 산지지역에 분포하는 지형경관은 고령읍의 미숭산과 주산, 그리고 덕곡면 노리의 상비리 계곡, 개진면 오사리의 고립구릉 등이다. 둘째, 하천 연안에 분포하는 지형경관은 개진면 부리의 진촌늪, 다산면 호촌리의 호촌늪과 달성습지, 우곡면 봉산리의 봉산늪 등의 자연습지, 고령읍 외리와 개진면 반운리의 보 축조에 따른 인공습지, 개진면 반운리의 곡류 절단에 따른 구하도와 곡류 핵, 고령읍 내곡리와 우곡면 월오리의 하식애, 우곡면 야정리의 넓은 모래톱과 망류하도 등이다. 셋째, 개진면 부리의 진촌늪은 전형적인 범람원의 모습을 갖추고 있고 비교적 보존상태가 양호하며 대도시와의 접근성도 양호하므로 생태공원을 조성하기에 적합하다. 그리고 개진면 반운리에는 탐구학습장을 조성하여 감입곡류의 절단과 연관된 환경변화와 보의 생태학적 순기능을 관찰할 수 있는 기회를 확대하여야 한다.

• Progress in Superconductivity
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• 제6권2호
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• pp.113-117
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• 2005

In this study, electromagnetic analysis of current paths including meander pattern, spiral pattern, and bi-spiral pattern were performed and in order to verity the analysis results, experiments tests including quench test, and insulation tests were performed. In addition, bubble corner concepts were introduced to enhance insulation reliability. From our study, bi-spiral pattern of YBCO thin films were rather effective for quench and insulation than the other patterns. So this current path pattern was adopted for YBCO thin films in order to develop 6.6 kV resistive fault current limiters. Finally YBCO thin films were connected in series and parallel to enhance capacity, and the test results of current limiting characteristics of 6.6kV resistive SFCL were successful. The Progress in Superconductivity is published every six month and serves as a channel for publications on superconductivity and related topics. The author(s) are required to submit THREE copies of the manuscripts along with original figures directly to the Editor.

• 한국지형학회지
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• 제27권1호
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• pp.1-19
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• 2020

A river bed which is submerged in water at high flow and becomes part of the river at low flow, serves as a bridge between the river and the land. The channel bar creates a unique ecosystem with vegetation adapted to the particular environment and the water pool forms a wetland that plays a very important role in the environment. To evaluate anthropogenic impacts on the river bed in the Middle Yeongsangang River, the fluvial landforms in the stream channel were analyzed using multi-temporal remotely-sensed images. In the aerial photograph of 2005 taken before the construction of the large weirs, oxbow lakes, mid-channel bars, point bars, and natural wetlands between the artificial levees were identified. Multiple bars divided the flow of stream water to cause the braided pattern in a particular section. After the construction of the Seungchon weir, aerial photographs of 2013 and 2015 revealed that most of the fluvial landforms disappeared due to the dredging of its riverbed and water level control(maintenance at 7.5El.m). Sentinel-2 images were analyzed to identify differences between before and after the opening of weir gate. Change detection was performed with the near infrared and shortwave infrared spectral bands to effectively distinguish water surfaces from land. As a result, water surface area of the main stream of the Yeongsangang River decreased by 40% from 1.144km² to 0.692km². A large mid-channel bar that has been deposited upstream of the weir was exposed during low water levels, which shows the obvious influence of weir on the river bed. Newly formed unvegetated point bars that were deposited on the inside of a meander bend were identified from the remotely sensed images. As the maintenance period of the weir gate opening was extended, various habitats were created by creating pools and riffles around the channel bars. Considering the ecological and hydrological functions of the river bed, it is expected that the increase in bar areas through weir gate opening will reduce the artificial interference effect of the weir.