• The Korean Journal of Ecology
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• 제28권5호
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• pp.327-333
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• 2005

For the first time in Korea, plant size, distribution pattern and root growth form of Tamarix chinensis were surveyed at natural stand in Shiwha Lake, from June to July in 2005. T, chinensis grew in the range of 350 m towards north-south and 270 m in east-west direction. The mean number of stems germinated from same root system was 1.9. On the stem base, the numbers of living and dead plants were 1,398 and 114, respectively. Mean perimeter and height of 1,398 plants were $5.9{\pm}3.2$ cm and $159{\pm}51$ cm, respectively. By dividing into 10 classes based on the perimeter size, the largest number of plants were included in the second smallest class category. However, by dividing into 10 classes on the bases of plant height, variation in the number of plants along the height showed normal distribution curve. The heights of dead plants were small in perimeter but diverse in height. On the root base, the number of plants was the greatest in the smallest size class, and conspicuously decreased with size increment. Distribution of T. chinensis was clumped pattern. Age of the largest plant was 8-year. T. chinensis had two types of root growth. One was horizontal growth in the periphery of soil surface, and the other vertical growth.

• Journal of the Korean earth science society
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• 제26권1호
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• pp.9-29
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• 2005

By analyzing and integrating established geological field study instances, this study offered a new geological field excursion teaching model with several steps: unifying question raising. excursion generalization. intensive field direction, searching, primary conclusion, re-searching, group discussion. adjustment, and excursion summarizing. Then by Qualitatively assaying the responses which students showed after applying this teaching model, a concrete teaching plan was sought for earth science teachers who were planning to begin geological field excursion classes. Students evaluated very highly on the unifying question and excursion generalization because these items provided a sense of direction and an overall theme for geological excursion in advance. Also. since the students had little to none geological knowledge and field excursion experience, the intensive field direction gave them a lot of help with their field excursion activities. Students thought that coming up with a primary conclusion based on the summary of what they had observed in their activities was original. and highly valued the process of sharing different opinions in group discussions and drawing out a final conclusion. Teachers should help students develop a friendly atmosphere, by organizing group activities and continuously feedlng them with uniting questions and excursion generalization within the groups. Also they should prepare enough contents for intensive field direction and ways to get their points across. In the process, they should arrange beforehand detailed instructions for every outcome, with the intention of solving the question. Furthermore. teachers should follow carefully how conclusions are drawn. instruct students not to reach conclusions based on mere assumptions, and be aware of misconceptions students have toward geological phenomenon in advance, so that the discussion can be lead in the right direction.

• Journal of the Korean earth science society
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• 제28권6호
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• pp.673-685
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• 2007

The purpose of this study was to investigate Earth Systems Understandings (Mayer, 1991) and Earth Systems meaning generation reported by science-talented students who participated in a geological field trip. The eight (4 female and 4 male students) field trip reports were randomly selected among all the reports written by twenty eighth-grade students who joined Shiwha-Lake field trip in Korea. The three-step program, including preparation, field trip, and summary, was provided to the students in order to facilitate meaningful learning through outdoor teaming activities. Seven Earth Systems Understandings and thematic types (Keys, 1999) were used to analyze the reports. The results of this study indicated thai aesthetic views and stewardship toward the Earth, which were the most distinguishing characteristics in Earth Systems Education, were reflected on most of the reports. The results also showed that the students tried to represent their understandings in such a type as meaning extension, meaning enhancement, or meaning elaboration. Overall, many students used 'knowledge-telling' process with a long list of observations and facts, whereas a few students used higher-order 'knowledge-transforming' process by coordinating their findings with interpretations and reasoning in their writings.

• Journal of the Korean Association of Geographic Information Studies
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• 제9권4호
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• pp.224-232
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• 2006

This study investigates to detect Sea Surface Temperature (SST) and land cover change after tide embankment construction using Landsat Thematic Mapper (TM) Thermal Infrared (TIR) band data at Shihwa Lake and surrounding area. SST measurement is important for studies of both the structure of the ocean and as the thermal boundary between the ocean and the atmosphere. Since 1970s, the derivation of SST by satellite remote sensing (RS) has been applied to earth surface using Advanced Very High Resolution Radiometer (AVHRR) and Landsat TM. However, AVHRR has restriction in deriving SST in the area whose shoreline is complicated like western coast in South Korea because of coarse spatial resolution. The TIR band of TM images can be used to detect SST change whose shoreline is complicated and narrow like the study site. Thus, multi-temporal TM images were used for SST change detection in this study.

• Journal of Korea Water Resources Association
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• 제41권5호
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• pp.473-482
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• 2008

The purpose of this study is to quantitatively estimate the erosional properties for cohesive sediment from Saemankeum artificial lake. A series of erosion tests were conducted with Chonbuk annular flume, which is the first one constructed in this country and verified with validities. Each erosion tests were conducted under a uniform bed condition but a different bed density respectively, and its critical shear stress for erosion(${\tau}_{ce}$) as well as the erosion rate coefficient (${\varepsilon}_M$) were determined quantitatively. Since the erosional properties of the cohesive sediments vary largely depending in the physico-chemical properties, such properties of Saemankeum sediments were also estimated and their effects on the erosional properties were analyzed. For Saemankeum sediments, it can be seen that ${\tau}_{ce}$ increases from $0.26N/m^2$ to $0.52N/m^2$ and ${\varepsilon}_M$ decreases exponentially from $14.28mg/cm^2\;hr$ to $6.02mg/cm^2\;hr$, as the bed density varies from $1.17g/cm^3$ to $1.34g/cm^3$. The erosional parameters of Saemankeum sediments are found to be remarkably different in quantity as compared with those for cohesive sediments from other sites. Particularly, ${\tau}_{ce}$ for Saemankeum sediments is known to be larger than that of Kunsan sediments but similar with that of Shihwa sediments, while ${\varepsilon}_M$ for Saemankeum sediments is shown to be smaller than that for Kunsan sediments.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 한국대기환경학회 2000년도 춘계학술대회 논문집
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• pp.356-358
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• 2000

ISC3는 EPA가 권장하는 가우시안 대기확산 모델로서 일반적으로 공장 배출원으로 인한 일정 기간동안의 대기확산농도와 범위를 예측하기 위하여 사용되어진다. ISC3 모델은 다양한 점오염원, 면오염원, 등을 취급할 수 있을 뿐 아니라 building wake와 down wash 그리고 거리의 함수로써 final plum rise를 옵션으로 사용할 수 있고 단순지형이나 복합지형의 고려가 가능하다. ISC3 모델은 단순지형 장기모델인 ISCLT3와 복합지형 단기모델인 ISCST3가 있으며 모델의 수행에 있어 약간의 차이점이 있다. (중략)

• Korean Journal of Ecology and Environment
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• 제43권1호
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• pp.55-68
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• 2010

The seasonal variation of microbial community, based on the bacteria, heterotrophic nanoflagellates (HNF), phytoplankton and ciliates, was investigated at three sites in the eutrophic brackish water of Lake Shihwa and its adjacent areas from May 2007 through May 2008. At the upstream-region site St. 1, compared to the other two sites, significantly lower salinities and higher concentrations of nutrients and chlorophyll $\alpha$ (Chl. $\alpha$) were recorded. The annual average abundances of bacteria at St. 1, St. 2 and St. 3 were $6.8{\times}10^6$, $7.4{\times}10^6$ and $4.6{\times}10^6\;cells\;mL^{-1}$, respectively. As for the annual average concentrations of HNF, $19{\times}10^2$, $6.7{\times}10^2$ and $5.9{\times}10^2\;cells\;mL^{-1}$, were recorded in St. 1, St. 2 and St. 3 respectively. The highest ciliate abundance appeared at St. 1 on 29 April, 2008 and in which, 99% were autotrophic ciliate Mesodinium rubrum (Myrionecta rubra). Significant linear correlations between the biomass of bacteria and Chl. $\alpha$ were found, however, no significant relationships between ciliates abudance/biomass and their prey organisms were detected in all three sites, implying relatively low energy transfer efficiencies between them. These results indicated that the trophic relationship between ciliates and their prey organisms in the microbial community might be influenced by indirect route since higher trophic level organisms did not directly correlate to those of lower trophic level, although high primary productions were detected in the eutrophic brackish water of Lake Shihwa and its adjacent areas.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.520-523
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• 2005

국내에서 대체에너지 공급 비율을 보면 청정에너지로 분류할 수 있는 태양열에너지, 태양 광 에너지, 풍력에너지를 모두 합하여 대체에너지의 $10\%$이하이며, 대체에너지 비율의 $90\%$ 이상을 폐기물로부터 얻은 에너지가 차지하고 있는 실정이다. 신재생에너지원에는 여러 종류가 있지만 해양에너지원에 대해 대상을 설정하고 이에 대한 부존량을 살펴보면 진도 주변의 해역에서 조류발전 부존량이 약 362만 kW가 되며, 시화호와 새만금 등지에서의 조력발전 부존량이 650만 kW, 동해안 후포 연안을 비롯한 파력발전 부존량이 20만kW가 되는 것으로 알려져 있다. 이에 따라 해양에너지를 실용화하기 위한 연구가 국내외에서 연구되고 있다. 본 논문은 권선형유도발전기를 갖는 조류발전 시스템을 대상으로 연구한 결과로 권선형유도발전기를 제어하기 위한 전력변환장치 개발과 관련한 내용이다. 신재생에너지원이 발전 단가 측면에서 경제성을 갖기 위해서 발전기 용량은 5MW 급까지 대용량화되어 있는 단계이지만 국내에서는 아직 MW급 이상이 되는 권선형 유도발전기와 권선형 유도발전기를 제어하는 전력변환장치에 대한 연구 실적이 없는 상황이다 이에 본 논문에서는 1MW급의 권선형유도발전기에 대한 개발 사례를 소개하면서 유효전력제어, 역률제어, 계통연계방법, 그리고 운전 속도에 따라 변동되는 회전자측에서의 피상전력 특성 등을 제시하고자 한다.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.1681-1685
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• 2006

현재 한국수자원공사에서는 시화호로 유입되는 유량을 저류하여 습지내 안정적인 유량을 공급함은 물론, 정화된 하천수를 방류하여 호소내 수질을 개선하고자 동화천 하류 약 840m 지점에 제수문을 설치하여 운영중에 있다. 그러나, 폭우시 상류농경지 침수우려에 따른 제수문 개방후 폐쇄시 제수문 담수어종이 상류로 올라가는 길이 차단되어 제수문 유출부에 어류가 폐사되는 현상이 반복되어 발생하고 있다. 따라서, 한국수자원공사에서는 동화천 제수문 하류부(약 36m)에 어도를 갖춘 수중보시설을 설치함으로써 제수문과 수중보사이에 Pond를 형성하여 어류의 자연사를 방지하고자 하였다. 이에 본 연구에서는 유량규모 및 수문개방 조건에 따른 보 설치 전 후 상황에 대한 1차원 수리특성분석을 실시함으로써, 보 설치로 인해 제수문 상류지역에 배수불량 상황 발생여부를 검토하고, 이를 배제하기 위한 제수문 개방조작 변경안을 제시하였다. 본 연구를 통해 제수문 하류단의 설치예정인 수중보가 제수문 상류지역의 배수상황에 미치는 영향은 제수문 상류 유입량이 저유량 구간인 $3.92cms{\sim}8.88cms$에서 발생하였으며, 이는 본 연구에서 제시한 개방수문 조작 변경안과 같이 간단한 수문조작을 통해 상류 수위를 저감시킬 수 있는 것으로 조사되었다.

• Journal of the Korean Association of Geographic Information Studies
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• 제4권1호
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• pp.27-33
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• 2001

SDD(Secchi disk depth) algorithm were composed of SeaWiFS bands combination using in-water optical data sets obtained Lake Sihwa, Kyungki Bay, Chunsu Bay, and Chinhae Bay. SDD algorithm were compared with in-situ data. Reflectance band ratio, $R_{rs}$(490/665) had the highest correlation($R^2$=0.8188) with in-situ data. For in-water algorithm applied to satellite data, reflectance band ratios of Landsat TM data were calculated. However, the results of applied Landsat TM had the low correlation, these reason were discussed in this paper.