• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1179-1183
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• 2007

관망 내에서 흐름의 연속 방정식과 운동량 방정식을 상 미분으로 전개하여 해석한 특성선 방법은 주로 가압 관망체계(Pressurized Pipeline System)에서의 부정류 해석(Unsteady Analysis)에 사용 된다. 그러나 이특성선 방법은 천이류 해석을 위한 관망 재구성 과정에서 Courant수 조건의 만족을 위한 관의 재배열에 천문학적인 계산용량과 시간이 필요하다는 단점이 있다. 이는 현장 적용 시 압력파 전파속도의 불확실성과 연계되어 상당한 장해요소가 되고 있다. 이에 대안적인 방법으로서 임펄스응답법이 개발되었다. 이는 경계지점에서 복소수 유량에 대한 복소수 수두의 비율로써 정의된 관망에서의 수리임피던스를 역퓨리에 변환에 적용하여, 주파수 영역의 수치를 시간 영역으로 변환하여 응답함수를 산출한 후, 산출된 응답함수와 구해진 경계지점에서의 유량과의 적분을 통하여 임의의 지점에서의 수두 및 유량을 계산하는 방법이다. 임펄스 응답법은 관 부속물관의 특성을 기술하는 수학적 표현의 난해함으로 인해 지금까지는 단일관에 대한 연구에만 국한되어 왔다. 본 연구에서는 임펄스응답법을 수리구조물이 부착된 관망에 적용하여 다양한 조건에서 천이류 분석을 시행하였다. 즉, 에어챔버 및 서지탱크와 같은 수리구조물을 각각에 대한 수리임피던스를 구하고, 가지관 및 통합 관성항으로 취급하여 수리구조물을 처리하였다. 그리고 이러한 결과를 특성선방법과 비교하여 그 적절성을 검증하였는데, 특성선 방법에 의한 모의 결과와 비교하였을 때, 일치하는 결과를 나타내었다. 임펄스응답법에 의한 모의 결과에서 감쇄효과를 과대평가하는 경향이 관찰되었다. 이는 임펄스 응답법의 가정에 기인한 것으로써 난류 상태의 흐름에서 상당한 불일치를 가져올 수 있으나, 수리 구조물에 의한 수격압이 감쇄되는 과정에서 대부분 흐름이 층류 상태로 전환된다고 가정 할 때는 상당한 적용성이 있다. 본 연구는 수리구조물이 부착된 관망의 해석함에 있어서 임펄스응답법의 적용이 가능함을 보였고, 이는 보다 복잡한 관망에서의 천이류 해석이 가능함을 시사한다.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.250-257
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• 2023

Tree in river have environmental functions such as ecosystem preservation and flood control functions that protect the riverbank. On the other hand, excessive tree development can have the negative effect of fixing the sand bar and reducing the cross-sectional area. Nays2D simulation results performing two flow conditions (average dam operation discharge and two-year frequency discharge) and four tree density conditions (current, zero, low, high tree density) used as input data for PHABSIM to calculate WUA (Weighted Usable Area). The results show that riverbed changes occur more significantly in the zero tree density than presence of trees, which could have a positive impact on the biological habitat environment of Zacco platypus.

• Journal of Science Education
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• v.39 no.3
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• pp.376-388
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• 2015

The purpose of this study was to develop the experiment-based problem for evaluating scientific ability of elementary scientifically gifted students, and to examine its potential of application for them. The problem for evaluating scientific ability was related to the plant vascular structure of 'the structure and function of plants' unit of elementary school science, and consisted of three components such as observing and inferring, designing an experiment, and concluding. In order to apply for scientifically gifted students, scoring criteria were detailed. For the observing and inferring domain, the arrangement and structure of vascular bundles of the dicotyledon and the monocotyledon, xylem position, reason of putting plants in ink were included. Those of designing an experiment domain were method of dissecting stems of plants, and design experimental procedures, those of concluding were the prediction of experimental results, and comparison and verification with prediction and results. Finally, the scientific ability evaluation problem was applied for 22 scientifically gifted students, who had been taught in the Science Education Institute for the Gifted adjacent University, and we had found the potential of utilization for scientifically gifted students.

• Korean journal of applied entomology
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• v.44 no.3 s.140
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• pp.177-187
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• 2005

For the comparison of feeding behavior of Nilaparvata lugens among different rice varieties, electrical penetration graph (EPG) technique was used. Ten rice varieties were selected from national-widely recommended rice varieties cultivating in Chungnam province. The correlation between feeding duration and honeydew amount excreted was investigated, and the types of EPG pattern were analyzed among rice varieties. The EPG patterns divided into 6 types according to electrical specific feature, respectively. Type 1 pattern was a searching feeding sites, resting or wandering on a rice plant. Type 2 pattern was appeared when the insect untaken from phloem sieve element. Type 3 pattern was observed when the insect piercing into the rice plant. Type 4 pattern was observed when the insect salivating in rice plant. Type 5 pattern was observed when the insect ingesting from the xylem. Type 6 pattern was observed when the stylet moving in cell. Feeding duration time on Gum-nam was significantly shorter than Dong-jin, Dae-ahn, Dong-ahn, Dae-san. Also, on Gun-nam, it was shown that the brown planthopper did not penetrate the cuticle for a long time. The total number of excreted honeydew droplets by the brown planthopper was the greatest in Dong-jin variety and the least in Gum-nam variety. In proportion to phloem feeding time, the number of honeydew droplets had been increased. According to the results of EPG patterns and honeydew droplets analysis, N. lugens seems to prefer Dong-jin, Dong-ahn, Dae-san, and Dae-ahn to Gum-nam, Da-san, and Nam-chun rice plant variety.

• Horticultural Science & Technology
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• v.34 no.5
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• pp.692-700
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• 2016

The objective of this study was to determine the differences in fruit growth, fruit quality, and particularly the pedicel vascular bundles of 'Shigyoku' and 'Heukboseok' grapes, which appeared to be different in softening at harvest. 'Shigyoku' grape matured faster (by about 20 days) than 'Heukboseok' grape with slight fruit enlargement after veraison. However, fruit of 'Heukboseok' grapes showed remarkable enlargement in both the primary and secondary fruit enlargement periods. Hypodermal cell layers were not different after veraison in 'Shigyoku' grape, but degradation of the hypodermis cell wall continued in 'Heukboseok' grape, resulting in a gradual decline in firmness. The numbers of hypodermal cell layers in 'Shigyoku' and 'Heukboseok' grapes were 14.2 and 9.0, respectively. The average content of soluble solids in 'Shigyoku' grape ($19.5^{\circ}Brix$) was significantly ($p{\leq}0.01$) higher than that of 'Heukboseok' grape ($17.0^{\circ}Brix$). Xylem of the pedicel did not differ between the two varieties. However, average phloem area after veraison of 'Shigyoku' grape ($19044.8{\mu}m^2$) was about 1.8 fold greater than that of 'Heukboseok' grape ($10509.4{\mu}m^2$), based on the number of cells constituting the phloem. The cell number and area of the phloem might affect the accumulation of sugars, the main constituents of the cell wall, thus maintaining the firmness of grapes until late maturity. Therefore, the increased softening of 'Heukboseok' grapes at harvest might due to their phloem structure.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.72-81
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• 2016

Feeding behaviors of the pear psylla, Cacopsylla pyricola, and their changing feeding behaviors were recorded and analyzed with an electrical penetration graph (EPG) analysis against 5 insecticides. And their mortality against insecticides were carried out in the laboratory. General feeding behavior patterns of C. pyricola were changed by insecticide treatments. Especially, the type and frequency of waveforms differently occurred depending on a sort of insecticides treated. Total duration of transition to waveform PE1 and phloem ingestion (waveform PE2) were significantly different between treatment and non-treatment of insecticides. When 5 different insecticides were treated on pear leaves, difference of feeding patterns were recorded. In case of treatment of benfuracarb, total duration of non-probes (waveform Np) was appeared higher than any other insecticide. However, when flonicamid and deltamethrin were treatment, total duration of stylet penetration (waveform PA) and xylem ingestion (waveform PG) were appeared higher than other insecticide, respectively. As results feeding behaviour of C. pyricola after treated insecticides with time-based consumed rate of C. pyricola, the rate of non-probe (waveform Np) was longer than start penetration (waveform PA), penetration and ingestion in parenchyma cells (waveform PC1+PC2), ingestion at phloem (waveform PD+PE1+PE2) and xylem (waveform PG). As result of direct spray treatment to C. pyricola, mortality of C. pyricola against imidacloprid was higher than any other insecticide on 24 hours after treatment. However, all of insecticides showed 100% mortality of after 48 hours. On the other hand, when 5 insecticides sprayed on the pear leaves and then C. pyricola located on the treated leaves, benfuracarb showed the most toxicity against C. pyricola among insecticides. These result was consistent with the EPG results that showed relatively longer total duration time of waveform Np (non-probes) by benfuracarb treatment.

• Korean Journal of Plant Resources
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• v.25 no.1
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• pp.156-168
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• 2012

Chrysanthemum is a cut flower species that normally lasts for 1 to 2 weeks, in some cases 3-4 weeks. This has been attributed to low ethylene production during senescence. Reduction in cut flower quality has been attributed to the formation of air embolisms that partially or completely blocks the water transport from the vase solution to the rest of the cut flower stem, increasing hydraulic resistance which may cause severe water stress, yellowing, wilting of leaf, and chlorophyll degradation. Standard type chrysanthemum can be harvested when buds were still tightly closed and then fully opened with the simple bud-opening solution. Standard type chrysanthemum can also be harvested when the minimum size of the inflorescence is about 5-6 cm bud which opened into the first flower full-sized flower. While spray varieties can be harvested when 2-4 most mature flowers have opened (40% opening). Cut flowers are sorted by stem length, weight, condition, and so on. Standard chrysanthemum is 80 cm length for standard type and 70cm for spray type. Pre-treatment with a STS, plant regulator such as GA, BA, 1-MCP, chrysal, germicide, and sucrose, significantly improved the vase life and quality of cut flowers. It is well established that vase solutions containing sugar can improve the vase life of cut chrysanthemum. Chrysanthemum is normally packed in standard horizontal fiberboard boxes. Chrysanthemum should normally be stored at $5{\sim}7^{\circ}C$. Precooling resulted in reduction in respiration, decomposition, and transpiration activities as well as decoloration retardation. There was significant difference between "wet" storage in 3 weeks and "dry" storage in 2 weeks. In separate pulsing solution trials, various germicides were tested, as well as PGRs to maintain the green color of leaves and turgidity. Prolonging vase life was attained with the application of optimal solution such as HQS, $AgNO_3$, GA, BA and sucrose. This also retarded senescence in leaves of cut flower stems. Fresh cut chrysanthemum can be transported using a refrigerated van with $5{\sim}7^{\circ}C$. Increasing consumption and usage of cut chrysanthemum of various cultivars would require efficient transport system, and effective information exchange among producer, wholesaler, and consumer.