• 한국주조공학회지
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• 제39권1호
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• pp.7-13
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• 2019

Few studies of large blooms over 700 mm thick among those used for the forging of raw materials have been reported. The cooling rate difference between the surface and the center of a large bloom is large, and the degradation of the mechanical properties is likely in cases involving excessively coarse precipitates resulted from the slow cooling rate of a large bloom after casting. Therefore, a schematic investigation of the growth behaviors of precipitates while varying their locations in blooms is necessary. The dissolution behaviors of precipitates were investigated by simulating a reheating process during which the bloom is heated to a high temperature. The segregation behavior of the as-cast large bloom was also investigated. Reheating specimens were obtained after an isothermal heat treatment at $1150^{\circ}C$ with various holding times to simulate the reheating process, with the samples undergoing a subsequent water quenching step. The precipitates were extracted using an electrolytic extractor and a particle size analysis was conducted with the aid of SEM, EDS, and TEM. In the present work, Al oxide, MnS and Nb carbide were mainly observed.

• 한국멀티미디어학회논문지
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• 제11권12호
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• pp.1688-1696
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• 2008

We propose a hierarchical service management method using Bloom filters for large MANETs. In this paper, a MANET is comprised of logical grid hierarchy, and each mobile node within the lowest service region multicasts the Attenuated Bloom Filter (ABF) for services itself to other nodes within the region. To advertise and discovery a service efficiently, the server node of the lowest server region sends the Summary Bloom Filter (SBF) for the ABFs to the server node of upper server region. Each upper server has the set of SBFs for lower vicinity service regions. The traffic load of the proposed method is evaluated by an analytical model, and is compared with that of two alternative advertisement solutions: complete advertisement and no advertisement. As a result, we identify that the traffic load of the proposed method is much lower than that of two alternative advertisement solutions.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.328-331
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• 2006

Eight years of SeaWiFS data quantify variability in the time/space patterns of spring bloom development in the Gulf of Maine (GOM). Maximum and earliest spring bloom are usually observed over Georges Bank, later on the deep basins from the west to the east GOM, and latest development along the eastern Maine coast in cold, tidally mixed water. Pronounced interannual variability of spring bloom timing, spatial position, and magnitude are shown in the GOM. Strongest negative anomalies are present in April 1998 and 2001 over Georges Bank and the eastern GOM, and in January to April of 2005 over the most of GOM. Positive anomalies are strong in April 2001, 2003 and 2004 in varying locations as well as in February and March 1999. It is suggested that interannaul variability in spring phytoplankton bloom concentrations is strongly associated with changes in water mass and stratification which might be influenced by basin-scale forcing due to large climate change.

• 한국전자통신학회논문지
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• 제12권3호
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• pp.457-464
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• 2017

하천에서 조류의 대량 번식은 녹조를 일으키고 수자원 안전에 대한 심각한 국가적 문제로 제기되고 있다. 따라서 깨끗한 용수를 확보하여 안정적인 수자원 공급을 위해 녹조로 인한 수질오염의 방재 기술 개발이 필요하다. 이에 본 연구는 무인항공기를 이용한 녹조 모니터링 기법을 적용하여 하천의 수질 관리 능력을 향상 시키고자 하였다. 녹조현상이 빈번하게 발생하는 낙동강 중류의 도동 나루터를 대상으로 무인항공영상을 취득하였다. 또한 녹조시료 채취 및 수질검사를 통해 식물성 플랑크톤의 현존량을 조사하였다. 무인항공영상에 녹조 탐지 지수식을 적용한 결과와 식물성 플랑크톤의 현존량 간의 상관관계가 강한 양의 관계를 가지는 것으로 나타났다. 본 연구에서 제안된 원격탐사 기술은 하천 수질 오염 초기 대응 능력을 향상시킬 것으로 기대된다.

• 한국정보통신학회논문지
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• 제21권6호
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• pp.1113-1120
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• 2017

최근 정보통신 기술의 발달로 인하여 데이터의 양이 점차 증가하고 있으며, 이에 대한 처리와 관련된 연구가 활발히 진행되고 있다. 주어진 집합 내에 특정 개체의 존재여부를 알기위해 사용되고 있는 블룸필터는 데이터의 공간 활용에 매우 유용한 구조이다. 본 논문에서는 블룸필터의 긍정오류확률에 대한 요인분석과 함께, 긍정오류를 최소화 시키기 위한 방안으로 병렬구조 방식의 블룸필터를 제안한다. 일반 블룸필터의 최소 긍정오류확률값을 가질 수 있도록 구현된 병렬 불룸필터 방식은 일반 블룸필터 크기의 메모리와 유사한 크기를 사용하지만, 해쉬함수별로 병렬 처리함으로서, 속도를 높일 수 있다는 장점을 가진다. 또한 완전 해쉬함수를 사용하는 경우에는 삽입뿐 아니라, 삭제도 가능하다는 장점을 가진다.

• 생태와환경
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• 제38권4호통권114호
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• pp.503-509
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• 2005

작은 부영양 저수지에서 수화를 형성하는 Mallomonas elongata의 계절적 변동(2004년 10월-2005년 9월)과 온도와 pH에 대한 증식 특성을 실험실 배양을 통해 조사하였다. 수온 12-$18^{\circ}C$, pH8.4-9.5의 범위를 나타낸 3월 말에서 4월 초의 짧은 기간 동안 M. elongata의 심한 bloom (최고 17,600 cells $mL^{-1}$이 발생하였다. 이 저수지로부터 분리한 M. elongata의 batch culture를 통한 다양한 온도에 대한 성장 반응은 bloom을 형성 하였을 때의 저수지 수온과 유사한 $15^{\circ}C$ 에서 최대성장률을 나타내었다. 반면 pH에 대한 증식 특성은 bloom 형성기의 저수지 pH 범위 보다 낮은 pH 6에서 최대 성장률을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제14권2호
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• pp.290-296
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• 2004

The effects of potassium, sodium, calcium, magnesium, and iron on cyanobacterial bloom potentials were investigated in Daechung Reservoir, Korea. Potassium showed the highest correlation with the cyanobacterial cell number (r=0.487, P<0.05) and phycocyanin concentration (r=0.499, P<0.05). However, it was not likely that the potassium had directly affected the bloom formation, because the variations of its concentration were not significantly large. In contrast, the Fe concentration fluctuated drastically and exhibited a negative correlation with the cyanobacterial cell number (r=- 0.388, P<0.1) and phycocyanin concentration (r=-0.446, P<0.05). Accordingly, the K:Fe atomic ratio would appear to reflect the extent of cyanobacterial bloom more precisely than K or Fe alone. The K:Fe ratio specifically correlated with cyanobacterial percentage, the cyanobacterial cell number and phycocyanin concentration (r=0.840, P<0.001; r=0.416, P<0.05; r=0.522, P<0.01, respectively). With the K:Fe atomic ratio of over 200, the chlorophyll-a concentration, cyanobacterial cell number, and phycocyanin concentration exceeded $10\mu$g $1^{-1}$20,000 cells $ml^{-1}$, and 20 pM, respectively, the general criteria of eutrophic water.

• 한국초등과학교육학회지:초등과학교육
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• 제31권1호
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• pp.1-12
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• 2012

The purpose of this study was to explore instructional objectives of 'Wise Life' based on Bloom's Revised Taxonomy of Educational Objectives. It was to extend understanding the 7th and the revised Wise Life 2007 as well. The written objectives of two curriculum of Wise Life were divided into two, the 'knowledge' dimension and the 'cognitive process' dimension based on Bloom's Revised Taxonomy of Educational Objectives. Major activity subjects presented in the 7th and the revised Wise Life 2007 were dominantly the basic inquiry activity types. It was found from this research that the 'factual' knowledge of the 'knowledge' dimension and the 'understand' of the 'cognitive process' dimension took a large proportion of the revised Wise Life 2007 objectives. The 'meta-cognitive' knowledge was increased. 'Remember' of the 'cognitive process' dimension was decreased and the high level objectives as 'analyze' and 'create', in the 'cognitive process' dimension was increased from the 7th to the revised curriculum. The 'factual' knowledge, 'conceptual' knowledge and 'metacognitive' knowledge were engaged with 'understand' and the 'procedural' knowledge were engaged with 'apply'. The 'meta- cognitive' were engaged with 'create' is the 'procedural' knowledge in the revised Wise Life 2007. 'Remember' was decreased. 'Create' was increased in the basic inquiry activities. It was analysed in zero percent of 'Observing', 'Investigating and Presenting', and 'Making'.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.325-328
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• 2004

This paper deals with void crushing behavior by ingot forging process which consists of sequential operations of upset forging and bloom forging. The predicted results of void crushing behavior by the simplified global-local method using F.E. analysis showed that the inherent void at the top region of the ingots remains incompletely crushed even after several forging operations. From the results of the hot upset forging test using the billets with drilled voids, it was found that the bonding efficiency of the void after forging process increases with an increase in deformation, and a decrease of initial diameter of voids.

• 한국물환경학회지
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• 제29권5호
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• pp.641-647
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• 2013

We installed mesocosms including zooplankton, fishs, artificial marshy land and aquatic macrophytes in Kyoungan stream to study the reduction effects of algae from Sep. 16 to Oct. 28, 2011. The control tendency of phytoplankton taxa was compared by analyzing community structure and dominant species in each mesocosm. Under the condition where Bluegill was absent, Daphnia similoides showed good effect of algal control since it has large food area and has high grazing pressure. Bluegill selectively preys upon large zooplankton, Daphnia similoides, as it also preys on small zooplanktons that flow in. In condition that Bluegill was absent, Daphnia similoides preyed selectively large phytoplankton (Cryptomonas ovata). Due to the shading of light, removal of nutrients and providing refuge for small zooplanktons, aquatic macrophytes and artificial marshy land showed high level of algal control. In corrals with aquatic macrophytes and artificial marshy land, the dominancy of genus Coelastrum and Pediastrum, which are difficult for small zooplanktons to feed on, relatively increased. In conclusion, under conditions of small number of predators such as Bluegill, Daphnia similoides is thought to be useful in algal bloom; however, when lots of predators are present, using small sized zooplanktons along with artificial marshy land and aquatic macrophytes is thought to be more useful than using large zooplanktons.