• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.527-531
• /
• 2007

하천내에서 작은 물고기의 국지적인 회유 또는 이동 습성은 먹이를 구하고, 산란 및 성장과 집단에서 분산하고, 위험으로부터 도피하는 것에 밀접한 연관이 있다. 하천의 합류부와 연결부에 제방(levee), 도로(road) 등이 설치되는 경우 일반적으로 암거형태의 인공수로로 상 하류를 연결되는데, 암거내 수리특성상 평수시 저유량, 고유속, 저수심의 수리특성을 보인다. 이러한 수리특성은 물고기가 이동하는데 장애(barrier)가 되어 생태적으로 하천내 종다양성 감소와 일부 어종의 멸종을 초래한다. 어도 설치시 설계기준에서 가장 주목할 부분은 어도를 이용할 대상어종의 범위와 유영능력이다. 하천설계기준(2005, 한국수자원학회)에서 제시된 물고기의 유영능력은 대부분 국외 어종을 대상으로 외국에서 실험한 결과를 이용하고 있다. 그러므로 이러한 기준이 국내 어종에 대해 적합한지에 대한 검토가 필요하다. 본 실험의 목적은 국지회유성인 피라미와 각시붕어가 인공수로를 통과할 때의 유영행동 중 소상성공율과 유영속력을 평가하고자 함이다. 유영행동의 실험방법은 Brett(1967)에 의해 제안된 2가지 방법인 증진유속방법과 고정유속 방법중에서 물고기의 이동경로와 소상능력을 확인하기에 용이한 고정유속방법을 사용하였다. 또한, 효과적인 실험을 위해 실험어종(피라미 100마리, 각시붕어 100마리)이 실험 중에 최적의 건강상태를 유지할 수 있도록 물고기의 적응 기간(24시간)과 실험 중 휴식기간을 두었다. 실험결과 체형이 방추형(fujiform)인 피라미의 경우 평균유속 $0.7{\sim}0.8m/s$구간에서 소상성공율이 61%에서 26%로 급격하게 하락하는 현상이 나타났다. 그리고 측편형(compressiform)의 체형을 가진 각시붕어의 경우 평균유속 0.4m/s에서 소상성공율이 25%로 나타났으며 그 이상의 유속에서는 10%이하로 나타났다. 실험어종의 이동경로를 분석한 결과 대부분 수로바닥에 밀착하여 최저유속구간을 이용하여 이동하는 것으로 나타났으며, 이동경로의 지점유속은 평균 유속의 70%정도로 나타났다. 실제 하천에 설치된 인공수로가 생태통로의 기능을 유지하기 위해서는 평상시 수리특성이 대상어종의 유영능력을 초과하지 않도록 설계되어야 한다. 특히, 하천에 설치된 인공수로의 길이가 $5{\sim}10m$정도일 경우라면 피라미의 소상 가능성을 50% 이상 확보하기 위해서는 평수시 설계유속이 0.7m/s를 초과하지 않아야 할 것으로 판단된다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.12
• /
• pp.1337-1344
• /
• 2014

The objective of an echo canceller connected to any end of a communication line such as digital subscriber line (DSL) is to compensate the outgoing transmit signal in the receiving path that the hybrid circuit leaks. The echo canceller working in a full duplex environment is an adaptive system driven by the local signal. Conventional echo canceller that implement the least mean square (LMS) algorithm provides a low computational burden but poor convergence properties. The length of the echo canceller will directly affect both the degree of performance and the convergence speed of the adaptation process. To cancel long time-varying echoes, the number of tap coefficients of a conventional echo canceller must be large, which decreases the convergence speed of the adaptive filter. This paper proposes an alternative technique for the echo cancellation in a telecommunication channel. The new technique employs the bi-directional least mean square (LMS) algorithm for adaptively computing the optimal set of the coefficients of the echo canceller, which is composed of weighted combination of both feedforward and feedback algorithms. Finally, Simulation results as well as mathematical analysis demonstrates that the proposed echo canceller has faster convergence speed than the conventional LMS echo canceller with nearly equivalent complexity of computation.

• Journal of KIISE:Computer Systems and Theory
• /
• v.27 no.3
• /
• pp.287-299
• /
• 2000

In this paper, we classify multicast methods into three categories, i.e., tree-based, path-based, and hybrid-based multicasts, for a multicomputer employing the bidirectional torus network and wormhole routing. We propose the dynamic partition multicast routing (DPMR) as a path-based algorithm. As a hybrid-based algorithm, we suggest the hybrid multicast routing (HMR), which employs the tree-based approach in the first phase of routing and the path-based approach in the second phase. Performance is measured in terms of the average latency for various message length to compare three multicast routing algorithms. We also compare the performance of wormhole routing having variable buffer size with virtual cut-through switching. The message latency for each switching method is compared using the DPMR algorithm to evaluate the buffer size trade-off on the performance.

• The korean journal of orthodontics
• /
• v.22 no.3 s.38
• /
• pp.491-507
• /
• 1992

Biennial serial cephalometric radiographs of 47 children (26 boys, 21 girls) were used to analyze the craniofacial growth changes in Korean children from 8 years to 16 years of age. A craniofacial model was designed for this study. It consisted of 72 anatomical points and 98 derived points. The craniofacial changes of these samples during these ages might be summarized as follows: 1. Mandibular growth to cranial base was more forward than maxillary growth. 2. Mandibular growth during this period was found to be a forward-upward (bite closing) rotation of the mandible. 3. Growth changes in total mandibular length (Ar-Gn) showed a pubertal growth spurt at 12-14 years of age in boys and 10-12 years of age in girls. Synchrony of the growth spurts on total mandibular length (Ar-Gn) and standing body height was found. 4. The pubertal spurts occured in the growth of total cranial base (Ba-Na) at 10-12 years of age in boys and 8-10 years of age in girls. The time of the spurts of the cranial base growth was 2 years ahead of that of the total mandibular growth. 5. Synchrony of growth spurts in anterior facial height (Na-Me), posterior facial height (S-Go) and body height was found. 6. The whole craniofacial changes during this period were plotted by using a X-Y plotter and personal computer. A simple profilogram for an diagnostic tool was obtained.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.1
• /
• pp.276-290
• /
• 2023

Several efforts in Korea are currently underway with the goal of commercializing autonomous vehicles. Hence, various studies are emerging on autonomous vehicles that drive safely and quickly according to operating guidelines. The current study examines the path search of an autonomous vehicle from a microscopic viewpoint and tries to prove the efficiency required by learning the lane change of an autonomous vehicle through Deep Q-Learning. A SUMO was used to achieve this purpose. The scenario was set to start with a random lane at the starting point and make a right turn through a lane change to the third lane at the destination. As a result of the study, the analysis was divided into simulation-based lane change and simulation-based lane change applied with Deep Q-Learning. The average traffic speed was improved by about 40% in the case of simulation with Deep Q-Learning applied, compared to the case without application, and the average waiting time was reduced by about 2 seconds and the average queue length by about 2.3 vehicles.

• Research in Plant Disease
• /
• v.8 no.3
• /
• pp.171-174
• /
• 2002

Powdery mildew of eggp1ant was found in Yeoiu, Korea in autumn 2000. Many white and Powdery mycelial colonies appeared on leaves, petioles and branches of the plants. Conidia with fibrosin bodies were ellipsoid to elongate-ellipsoid, 25~40$\times$15~22 ${\mu}{\textrm}{m}$ in size and formed in chains with crenate edge. Conidiophores were erect on superfical mycelium, 47~100 ${\mu}{\textrm}{m}$ in length. Germ tubes from conidia were simple and unbranched. No cleistoth-ecia were observed. On the basis of morphological characters of the conidial stage, the fungus was identified as Sphaerotheca fusca.

• Journal of Wetlands Research
• /
• v.24 no.4
• /
• pp.288-300
• /
• 2022

As industrialization and urbanization progress extensively, climate change is intensifying due to greenhouse gas emissions. In Korea, the average temperature increased, and the annual precipitation also increased due to climate change. In addition, the meaning of the solar term, which expresses seasons according to the movement of the sun, is also being overshadowed. Therefore, this study investigated the seasonal changes and solar-term changes of average temperature and precipitation observed in the past as well as simulated for future RCP climate change scenarios for five major regions (Capital Region, Gyeongsang, Chungcheong, Jeolla, and Gangwon). For the seasonal length, the length of summer became longer, the length of winter became shorter nationwide, and the precipitation in summer generally increased compared to the past. In the Chungcheong area, under the RCP 8.5 scenario, the length of summer increased by 46%, precipitation increased by 16.2%, and the length of winter decreased by 31.8% compared to the past. For the solar term, the temperature rose in all seasons. In the Chungcheong area, under the RCP 8.5 scenario, the temperature of major heat increased by 15.5%, and the temperature of major cold increased by 75.7% compared to the past. The overall results showed that the hydrological characteristics of the season and solar term were identified by region, which can be used as basic data to prepare policies to respond to climate change.

• Journal of Life Science
• /
• v.13 no.3
• /
• pp.359-364
• /
• 2003

The seaweed Porphyra pseudolinearis as a dominant species grows at upper of the intertidal zone of the East Sea from October to March. Vegetative cells have not matured during October when observed with naked eye and microscope. In the middle of November, although it didn't distingush between female and male gametophytes by eye, it showed antheridium and carpogonium when observed vertical section under microscope. From early December, It could be distinguished female and male gametophytes clearly. From Feburary it showed shorted length of thalli by release of spermatangia and carposporangia as maturation. At early March, the colar has been decaeded and side of thalli has been melted, completed of release of spermatia. At the end of December, the average length and width of female thalli were 149.9$\pm$5.6mm and 22.2$\pm$2.3mm, respectively. The length and width of male thalli were 149.9$\pm$9.4mm and 20.7$\pm$1.8mm. At the end of January, the average length and width of female thalli were 94.6$\pm$6.4mm and 29.1mm$\pm$5.1, respcetively. The length and width of male thalli were 107.8$\pm$7.3mm and 25.9$\pm$0.9mm. From this period lengths of female and male thalli have already been shortned by the release of spermatia and carpogonia.

• The Journal of the Korea Contents Association
• /
• v.9 no.8
• /
• pp.384-391
• /
• 2009

The coastline area, which was the important to decide the shape of the national land, has the characteristics of changing its shapes and features. We have some trouble to make the appropriate use-plan, because of the huge land to be reclaimed from the sea and developing large and small coast areas. Of them the coastal sand dune plays a definite primary role in the side of tourism and ecology. But there is not enough study for that. Busan Songdo coast is decided as an object of this study. We would analyze transfer path of the coastal sand dune through the time series analysis with RTK-GPS survey for many years. In case of Song do coast, the mean coastline length is approximately 620m, the area is approximately $31,846m^2$. Breakwaters are set up in right and left sides in Song do coast. it can make the sand dune be a minimum. So the coastal sand dune is steadily deposited with a certain beach nourishment of every year. As a result of 7 times survey, both sides of the coastal sand dune are eroded. It turns out it is going ahead over all as the center of the coastal sand dune is deposited.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.1
• /
• pp.94-100
• /
• 2012

The passive control by vertical splitter plate of fluid force acting on a square prism near a plane wall was studied by measuring of fluid force on the prism and by visualization of the flow field using PIV. The hight of the splitter plate was 10% of the square width. The experimental parameters were the attaching position of vertical splitter plate and the space ratios G/B to the prism height. Time variation of vorticity was most remarkable at 3.0B(B: prism height) position toward wake direction from the center of the prism. The point of inflection of average lift coefficient and Strouhal number on the prism were represented at the space ratio G/B=0.4~0.6 for the prism having vertical splitter plate. The drag of the prism was reduced average 5.0% with the space ratios by attaching the vertical splitter plate at the upper and rear corner on the prism. In this case, the size of the separated region on the upside of the prism was smaller than that of prism having no the splitter plate.