• Journal of Korean Society of Water and Wastewater
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• v.26 no.2
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• pp.285-294
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• 2012

Current urban stream conditions and their restoration projects were investigated by surveying the urban stream management experts in 29 cities with high population density (more than 1,000person/$km^{2}$). The survey results showed that the ratio of covered urban streams decreased by 1.4% (from 14% to 12.6%) in the last 5 years through steady river restoration projects promoted by governments. Nonetheless, 36.3% of 369 urban streams surveyed still report stream depletion problems; therefore, more efforts to alleviate the problems caused by distorted water circulation of urban streams are still necessary. Water depletion in many local urban streams, unlike national rivers, is accelerated due to negligence in stream management, budget shortage, and other reasons. To prevent stream depletion, the use of reclaimed water is suggested as one of the prevention plans. When available amounts of reused sewage are estimated through actual available nationwide sewage discharges of each watershed and instream flow of stream, annual instream flow supply of 780 million $m^{3}$ is expected; 4.8% reduction in the pollution load of public sewer treatment facilities is expected; and the creation of new value through water reuse service is expected. Thus, it is important for the reviews of feasibility and alternatives of water reuse projects for flow augmentation to consider not only investment budget reductions, but also environmental aspects. Also it is necessary to provide the financial support of unified government with strict water quality management policy.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.153-163
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• 2009

This study was carried out to offer ecological restoration plan of local streams by analyzing the vegetation and flora around four local streams (Pungchoncheon, Namchangcheon, Ganggicheon, Woncheoncheon) in Namwon. Flora and vegetation investigation was done at April 2007 to August 2007, and June 2009. The 194 of vascular plants were identified which contain 53 families, 143 genera, 194 species. The Family frequencies arranged by the order of Family Compositae (14.4%), Family Gramineae (13.4%) Family Leguminosae (6.7%) and Family Polygonaceae (5.2%). The naturalized plants were listed as 33 species, and their naturalization ratio and urban index were found to be 17.0%, and 12.2%, respectively. In this study a total of 21 relev$\acute{e}$s collected and analyzed. 6 plant communities are differentiated : Riverine softwood forests (Phragmites japonica-Salix gracilistyla community), Perennial herb vegetations on lotic water zone (Phragmites japonica community, Phalaris arundinacea community), Perennial herb vegetations on lentic water zone (Persicaria thunbergii-Typha orientalis community, Phragmites communis community), Annual or biennial vegetations on waterside (Persicaria thunbergii community). Species showing the higer value in the plant communities were Persicaria thunbergii, Phragmites japonica, Artemisia princeps, Humulus scandens, Bidens frondosa, Oenanthe javanica, Agropyron tsukusinense var. transiens, Stellaria aquatica, and Lactuca indica var. laciniata.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.786-789
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• 1989

A nonlinear self-tuning regulator for a neutralization process of a weak acid and strong base system is proposed. Rearranging the state equation of the process model, we first obtain equations which are linear for a manipulated variable or unknown parameters. Then to these equations we apply the standard procedure used in designing linear self-tuning regulators. Simulation results show that the regulator provides very good performances for various realistic situations and traces variations of the unknown parameters. Since computations are simple and additional measurements except the effluent pH value are only flow rates of influent streams, it can be easily applied to real processes such as a waste water treatment process.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.93-102
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• 2007

The runoff characteristics of organic matter in turbid water were investigated in eleven tributary streams of the Han River system, Korea. The flow-weighted event mean concentrations of organic matter ranged from 1.5 to 3.2 mg $L^{-1}$ of DOM and 2.2 of 29.1 mg $L^{-1}$ of POM, respectively. The SUVA value which reflects the proportion of humic substance in organic matters was higher during the rainfall season, meaning that the runoff of refractory form increase in this period. Stable carbon isotope ratios of both POM and DOM were different among streams, which reflect the sources of organic matter. DOM isotope ratios were less depleted of $^{13}C$ than that of POM by approximately 1 to $2%_{\circ}$ ${\delta}^{13}C$ of the several turbid streams (the Mandae Stream, the Jawoon Stream, and the Daegi stream) were heavier than those of clear streams. ${\delta}^{13}C$ values in the turbid upstream tributaries were similar to those of downstream reaches (such as the Soyang River, the Sum River, and the Seo River). From the ${\delta}^{13}C$ analysis of POM it could be calculated that $C_4$ pathway contributed approximately 15.9 to 23.6% of organic matter in several turbid upstream sites, and over 20% in the three sites of large downstream reaches. On the contrary it contributed only 9.1 to 12.8% in clear streams of forest watersheds. In the Soyang River, $C_4$ pathway organic matter contributed 8.8% of the DOM pool.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.273-287
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• 2001

In this paper, we introduce our experience for designing and implementing a media manager in the Integrated Streaming Service Architecture (ISSA) developed by the authors. The media manager is regarded as a necessary module in the ISSA framework for the following reasons. It realizes that from which locations of the media source devices, the media streams are coming. Once it knows where the origin is, the media manager should recognizes what types of stream are. After that, it performs how to chose an appropriate CODEC to handle the recognized input streams efficiently, and what type of media playback device should be selected. In order to do such a job efficiently, the proposed media manager consists of two modules source module and sink module. The major role of a media source module is to make an abstraction for the media streams that are coming from various types of media device. This, in consequence, enables a media manager to consistently handle tlle media streams without considering wherever they come from. On the other hand, the media sink module distributes the input streams to an appropriate media device to playback. One of the remarkable virtues of the proposed media manager is an ability to supporting high value-added database services since it provides an interface between the ISSA and real-time multimedia database. Also, it provides the RTP!RTSP source filter and Winamp gateway modules which allow the flexibility to the system. Moreover, the media manager can adopt any types of new media which in fact will provide scalability to the ISSA.

• Journal of Korean Society of Forest Science
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• v.112 no.3
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• pp.374-381
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• 2023

The travel time of flash floods along mountain streams is mainly governed by reach-average velocity, rather than by the point velocity of the locations of interest. Reach-average velocity is influenced by various factors such as stream geometry, streambed materials, and the hydraulic roughness of streams. In this study, the reach-average velocity in mountain streams was measured for storm periods using rhodamine dye tracing. The point cloud data obtained from a LiDAR survey was used to extract the average hydraulic roughness height, such as R_a, R_max, and R_z. The size distribution of the streambed materials (D₅₀, D₈₄) was also considered in the estimation of the roughness height. The field experiments revealed that the reach-average velocities had a significant relationship with flow discharges (v = 0.5499Q^0.6165 ), with an R² value of 0.77. The root mean square error in the roughness height of the R_a-based estimation (0.45) was lower than those of the other estimations (0.47-1.04). Among the parameters for roughness height estimation, the R_a -based roughness height was the most reliable and suitable for developing the reach-average velocity equation for estimating the travel time of flood waves in mountain streams.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.2 no.2
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• pp.115-124
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• 1979

The purpose of this study is theoretical research on risk. The research is focused on systematic risk. Chapter I is objective of this study, Chapter II includes definition and measurement of risk. Chapter III introduces attitudes toward risk and classification of risk. Chapter IV discusses Portfolio theory, Capital market line and Shape and Lintner model The objective of firm is assumed to maximize its value. In a world of uncertainty, value is not determined by earnings alone, the degree of risk involved with the streams of earnings. Financial manager has to consider the risk in order to maximize the value of firm. Total risk can be classifier into two parts : Systematicrisk and unststematic risk by Sharpe. Systematic risk is important because investors can't diversify it. Blume and Jensen measured f and they testified that the f is stationary over the time For further study, Korean stock mark has to take emperical study about $\beta$ and its stationarity.

• Korean Journal of Ecology and Environment
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• v.36 no.1 s.102
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• pp.57-65
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• 2003

The algal growth potential test (AGPT) bioassay were conducted to assess the water quality and fertility in the Chinyang Reservoir and the lower part of the Nam River from August 2000 to July 2001, The AGPT value of the Chinyang Reservoir ranged from 0 to 23.4 mg dw $1^{-1}$, while 79% of the algae cultivation have not grown. The AGPT value was in proportion to phosphorus concentration of the water, and it was less when chlorophyll-a was high. This value was higher in the middle and lower layers than in the upper layer, and in the inflow part where the water is shallower than in the lacustrine. The AGPT value has increased in the whole reservoir in August${\sim}$September when the water volume is high. In contrast, the AGPT value in the Nam River varied greatly compared to that of the reservoir, and ranged from 0 to 252.0 mg dw $1^{-1}$ and 65% of the algae cultivation have grown. The value was less than 10 mg dw $1^{-1}$ in the upstream, over the point where the treated wastewater discharged. It was 57 mg dw $1^{-1}$ on the average in the downstream, except in March and July when the discharged water influenced greatly, exceeding the hypertrophic condition. The result of AGPT shows the differences in the time and space on the reservoir and the streams. The AGPT value has increased in July${\sim}$September, and in December in the inflow part of the reservoir; in March and August${\sim}$December in the lower part; and in January, May, and November in the streams. AGPT is useful not only in defining the influence of the limiting nutrients on the algal growth, but also in evaluating the nutrients fertility in the inland water.

• Journal of Environmental Impact Assessment
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• v.21 no.1
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• pp.143-160
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• 2012

The community of periphyton was studied at high altitude streams of the Han-river System, including Buk-stream and Hangae-stream from October to November 2010. The study had special emphasis on the distribution of the cryophilic and mountain periphyton. In this research, 117 taxa of periphyton appeared and 80 taxa of diatom were included within these periphytons. Saproxenous taxa, such as Achnanthes convergens and Hannaea arcus var. subarcus were appeared in most sites, 7 sites were dominant by filamentous taxa in green and blue green algae. The DAIpo value was from 48.8 to 92.5 for the water system of this research. Most sites showed a good water quality, receiving a B class or above except the Woljeong-stream and the Daeki-stream. Cryophilic and mountain periphyton appeared 9 taxa which composed by diatoms Cymbella affinis, Cymbella tumida, Diatoma mesodon, Diatoma vulgare, Eunotia pectinalis, Hannaea arcus, Hannaea arcus var. subarcus and Synedra inaequalis and green algae Ulothrix zonata. Among these taxa, Hannaea arcus var. subarcus, found in 29 out of 33 sites, had the highest frequency of apperance. The relative frequency of Hannaea arcus var. subarcus was positively correlated with altitude($r^2$=0.539) and negatively correlated with water temperature($r^2$=0.338). As a result, Hannaea arcus var. subarcus showed the characteristics of cryophilic and mountain periphyton in the research site.

• The Korean Journal of Ecology
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• v.19 no.5
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• pp.487-496
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• 1996

This study was conducted to investigate pollutant loading, were quality and plant distribution of 8 streams which are tributaries of the Youngsan River. The nitrate reductase activity (NRA) and nutrient removall capacity of the most frequently occurring aquatic plants on streamside were also determined. As a result, the pollutant loading appeared to be correlated with the area of watershed, while the water quality was related to the land use pattern of each steam. The aquatic plants were distributed differently among the streams; Hydrilla verticillata - Potamogeton crispus, Numphoides peltata - Hydrocharis dubia and Polygonum thunbergii - Phragmites japonica were dominant at the Orye Chon, Jungan Chon, Whangryong River and Jiseok Chon, while potamogeton crispus - Lemma paucicostata, Zizania latifolia - Phragmites communis were dominant at the Youngam Chon and Munpyeong Chon. Persicaria hydropiper and Echinochloa crus-galli var. oryzicola were dominant at Kwangju Chon which was polluted with domestic wastewater. >From the measurement of leaf NRA for dominant species, the highest value of NRA was shown by the Polygonum thunbergii, followed by Oenanthe javanica > Phragmites communis > Zizania latifolia > Lemma paucicostata. The highest nitrogen and phosphorus removal capacity was found in Phragmites communis.