• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.347-357
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• 2011

We examined two reservoirs (Inkyung res. and Joongang res.) and two streams (Kyungan str. and Jecheon str.), all of which were eutrophic, during the 2010 warm season, to evaluate the water quality improvement activity (WQIA) of plant-mineral composite (PMC), which was previously developed to control suspended solids, including cyanobacterial bloom (Kim et al., 2010). We simultaneously measured both solid (S-MCLR) and dissolved microcystin-LR (D-MCLR), before and after PMC treatment, in the Joongang reservoir. Taking water body size and volume into account, we conducted the whole-scale experiment in the Inkyung reservoir, and mesocosm-scale experiments in the other three systems. The WQIAs of PMC were found to be comparatively high in SS (70~81%), TP (75~91%), BOD (65~91%), Chl-a (88~98%), phytoplankton (84~92%) and zooplankton (68~88%), except for the Kyungan stream, which was below 45% in all parameters. After PMC treatment, the concentrations of both SMCLR (47%) and D-MCLR (96%) decreased within two days, suggesting a mitigation possibility of hazardous chemicals such as agrochemicals and endocrine disrupters in the aquatic ecosystem. Our results collectively indicate that PMC is a useful agent to control suspended solids, including nuisance cyanobacterial bloom and their exudates, in an undisturbed water system with a long residence time.

• Journal of Korea Water Resources Association
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• v.55 no.2
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• pp.111-120
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• 2022

The concept of soil moisture memory was used as a method for quantifying the function of soil to control water flow, which evaluates the average residence time of precipitation. In order to characterize the soil moisture memory, a new measurement index called stored precipitation fraction (F_p(f)) was used by tracking the increments in soil moisture by the precipitation event. In this study, the temporal and spatial distribution of soil moisture memory was evaluated along with the slope and soil characteristics of the surface (0~5 cm) soil by using satellite- and model-based precipitation and soil moisture in the Korean peninsula, from 2019 to 2020. The spatial deviation of the soil moisture memory was large as the stored precipitation fraction in the soil decreased preferentially along the mountain range at the beginning (after 3 hours), and the deviation decreased overall after 24 hours. The stored precipitation fraction in the soil clearly decreased as the slope increased, and the effect of drainage of water in the soil according to the composition ratio of the soil particle size was also shown. In addition, average soil moisture contributed to the increase and decrease of hydraulic conductivity, and the rate of rainfall transfer to the depths affected the stored precipitation fraction. It is expected that the results of this study will greatly contribute in clarifying the relationship between soil moisture memory and surface characteristics (slope, soil characteristics) and understanding spatio-temporal variation of soil moisture.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.31 no.4
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• pp.70-83
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• 2013

To widen prospect of villa as Korea traditional garden, the result of the research about constructional characteristics of Seogo-jeongsa and Sameun-jeong of Yeoju Lee family at Toero-ri, Miryang-si, Gyeongsangnam-do, Korea, is abstracted as below. Seogo-jeongsa(西皐精舍) and Sameun-jeong(三隱亭) was intended to practise retirement with sense of unity with the head residence, since Seogo-jeongsa was 340m far and sameun-jeong was 630m far away from head residence, which set within 1km. Although Seogo-jeongsa's basic prop, Sameun-jeong's timber, which are both from designer's pen name and head residence name, "Hangjae(恒齋)" and "Yongjae(庸齋)," and Hanseoam have each different exposure, it is homogeneous as space configurational side in order to optimize the gaze leading effect and appreciated domestic trees from the pond, which is center of the garden and the significant facility. Method of direction of Seogo-jeongsa's Hwalsudang(活水塘) and Sameunjeong's pond of Sameun-ji(三隱 池) gets attention by distinction. Especially, directing of 3 step water flow from behind to front and traditional pond method, called Bangji-Bangdo(方池方島), were very unique that any other place can be found. Also, the middle islet on the pond at both villa, which isn't more supper, but more for the symbolic molding that seek a stone pagoda(石假山), is more interesting directing method as considering the relationship of the 3 stone pagoda imageries on the surface of Ghwayukchon(果肉泉) At the same time, Seogo-jeongsa and Sameun-jeong shows very different characteristics from traditional villa that adopted both domestic trees and foreign trees. Particularly, it is extremely exceptional case to plant vigorous needleleaf tree, such as Chamaecyparis pisifera, C. obtusa, Pinus bungeana, P. palustris, Sciadopitys verticillata, Metasequoia glyptostroboides and Cedrus deodara, on Sameun-jeong. Moreover, adopting foreign wild needleleaf trees for landscaping trees, such as a Torreya nucifera, Taxus cuspidata, P. parviflora, and foreign landsacping trees, such as P. bungeana, Cryptomeria japonica and C. obtusa tells planting trend of the late Joseon dysnasty era. Also, as we can know from 2 Jipgyeong(集景), which is 'Seogo-jabyoung 17 young(西皐雜詠十七詠)', and 'Sameun-jeong 12 Gyoung(三隱亭十二景)' which are set on both villa, the intend to expand the garden area is strongly shown by the natural forest directing. As a result, Seogo-jeongsa and Sameun-jeong, located at Toero-li Miryang, are sharing the traditional Joseon dynasty era's custom, such as space and visual composition; however, it is different and attractive garden remains as a point of view of water directing, stone pagodas, and adopting foreign landscaping trees.

• Ecology and Resilient Infrastructure
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• v.7 no.3
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• pp.171-180
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• 2020

With the increase in industrialization and urbanization, scarcity of space for leisure life has become an important issue. Opportunities such as natural scenery and ecological experiences provided by waterfront spaces around streams are fundamental factors in the development of the community and creation of a hydrophilic park. In the past, on-site surveys have been conducted using human resources to quantify the number of river visitors, but the accuracy of the results was not sufficient owing to limitations in expenses, manpower, space, and time. In this study, to overcome this problem, we estimated the number of visitors using the location information related to hydrophilic parks. The study areas were Samrak Ecological Park and Daejeo Ecological Park located downstream of the Nakdong River. We compared and analyzed the pattern of the visitors by using the large communication data and the visiting pattern based on GPS location information. The GPS location information is based on Google Popular Times and Kakao visitor data. When the GPS location data were used, the pattern for weekday and weekend visitors was clearer than when the large communication data were used. Therefore, it is expected to be similar to the result of GPS location information if the number of visitors is extracted under the condition of precision of pCELL size and residence time of 30 minutes or more when using future communication big data. In addition, if revisions such as the Personal Information Protection Act are made to extract more accurate data, by estimating the number of visitors based on GPS data, more accurate indicators of the number of visitors can be derived.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.138-146
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• 2000

This study was performed to determine the best fermentation soil in vanishing composting of individual residence garbage. At the result, temperature, weight, water content, volatile solid were reduced gradually by reaction of microorganism in the reactors after food was inserted for 9 days. The vanishing possibility was observed in all reactors. The best reactor was F and 4 that seeded microorganisms which were provided at S University. In addition it was possible to shorten cycle of putting in food waste. Inactivated reactors will be bad because of increased water content for long reaction time. Sodium chloride was accumulated and not vanished as time passed. But reactor was not insulated, the activities of microorganism in the reactor were affected highly by cold weather(about less than $12^{\circ}C$). When the study was extended to find out the feasibility of application, the retention time could be shortened to 3days form 9 days, when the microorganism reactor that used the fermentation soil seeded microorganisms which were provided at S University was maintained about $20^{\circ}C$.

• 한국해양학회지
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• v.30 no.4
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• pp.279-287
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• 1995

The vertical profiles of natural ²¹⁰Pb, ²¹⁰Po and ²³⁴Th activities were measured for the upper 100 m of water column at three stations in the middle region of the Korean East Sea during May 1992. And the distribution of these radionuclides was discussed associated with the formation of warm eddy or water mass. The main thermocline was maintained between the depth of 50 and 100 m at the southern station (Sta. A1), and between the depth of 10 to 50 m at the coastal station of Sockcho (Sta. B10). Contrastingly, a main thermocline at Sta. A10, which locates near the center of warm eddy, was observed below 230 m depth. Between 50 and 220 m depth of Sta. A10 is there a relatively homogeneous water mass of 10.1${\pm}$0.5$^{\circ}C$, which is significantly higher in temperature and lower in nutrient than the other two stations. It seems to be due to sinking of the warm surface water in which nutrients were completely consumed. Both ²¹⁰Pb and ²¹⁰Po show the highest concentration at Sta. A1 and the lowest at Sta. B10 among the three stations. Also, the ²¹⁰Pb activity is generally higher in the upper layer than in the lower layer, while ²¹⁰Po activity represents the reversed pattern at all three stations. At Sta. A1 and Sta. B10, the activities of ²¹⁰Po relative to its parent ²¹⁰Pb were deficient in the water column above the main thermocline, but were excess below the thermocline. However, the station near the center of warm eddy(Sta. A10), shows no excess of ²¹⁰Po in the depths below 50 m, although its defficiency is found in the upper layer like the other stations. At Sta. A1 and b10. ²³⁴Th activities are slightly lower in the surface mixed layer than in the deeper region However, at Sta. A10, ²³⁴Th activity in the upper 30 m is higher than below 50 m or in the same depth of the other stations, probably because of the high concentration of particulate matter. The residence time of ²¹⁰Po in the surface mixed layer at Sta. A10 is 0.4 year, much shorter than at the other two stations(about one year). Above 100 m depth, the residence times of ²³⁴Th range from 18 to 30 other two stations(about on year). Above 100 m depth, the residence times of ²³⁴Th range from 18 to 30 days at all stations, without significant regional variation. The percentages of recycled ²¹⁰Po within the thermocline are 39% and 92% at Sta. A1 and Sta. B10, respectively. Much higher value at Sta. B10 may be due to a thin thickness of the mixed layer as well as the slower recycling rate of ²¹⁰Po in the main thermocline.

• Membrane Journal
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• v.32 no.4
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• pp.235-252
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• 2022

Forward osmotic pressure-free reverse osmosis (Δ𝜋=0 RO) was invented in 2013. The first patent (US 9,950,297 B2) was registered on April 18, 2018. The "Osmotic Pressure of Concentrated Solutions" in JACS (1908) by G.N. Lewis of MIT was used for the estimation. The Chang's RO system differs from conventional RO (C-RO) in that two-chamber system of osmotic pressure equalizer and a low-pressure RO system while C-RO is based on a single chamber. Chang claimed that all aqueous solutions, including salt water, regardless of its osmotic pressure can be separated into water and salt. The second patent (US 10.953.367B2, March 23, 2021) showed that a low-pressure reverse osmosis is possible for 3.0% input at Δ𝜋 of 10 to 12 bar. Singularity ZERO reverse osmosis from his third patent (Korea patent 10-22322755, US-PCT/KR202003595) for a 3.0% NaCl input, 50% more water recovery, use of 1/3 RO membrane area, and 1/5th of theoretical energy. These numbers come from Chang's laboratory experiments and theoretical analysis. Relative residence time (RRT) of feed and OE chambers makes Δ𝜋 to zero or negative by recycling enriched feed flow. The construction cost by S-ZERO was estimated to be around 50~60% of the current RO system.

• Resources Recycling
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• v.29 no.6
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• pp.104-113
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• 2020

Bubble size in froth flotation has long been recognized as a key factor which affects the bubble residence time, the bubble surface area flux (Sb) and the carrying rate (Cr). This paper presents method of bubble size measurement, relationship between operating variables and gas dispersion properties in flotation column. Using high speed camera and image analysis system, bubble size has been directly measured as a function of operating parameters (e.g., superficial gas rate (Jg), superficial wash water rate (Jw), frother concentration) in flotation column. Relationship compared to measured and estimated bubble size was obtained within error ranges of ±15~20% and mean bubble size was 0.718mm. From this system the empirical relationship to control the bubble size and distribution has been developed under operating conditions such as Jg of 0.65~1.3cm/s, Jw of 0.13~0.52cm/s and frother concentration of 60~200ppm. Surface tension and bubble size decreased as frother concentration increased. It seemed that critical coalescence concentration (CCC) of bubbles was 200ppm so that surface tension was the lowest (49.24mN/m) at frother concentration of 200ppm. Bubble size tend to increase when superficial gas rate (Jg) decreases and superficial wash water rate Jw and frother concentration increase. Gas holdup is proportional to superficial gas rate as well as frother concentration and superficial wash water rate (at the fixed superficial gas rate).

• Journal of the Korean Wood Science and Technology
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• v.39 no.6
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• pp.459-468
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• 2011

The main purpose of this study was to examine the influence of treatment amounts of Slurry Composting and Biofiltration liquid fertilizer (SCBLF) on biomass growth of Yellow poplar (Liriodendron tulipifera) and to compare bioethanol production from the harvested wood. Relative growth rate, biomass production and leaf characteristics were significantly enhanced by SCBLF treatment and medium treatment plot showed highest value. Nitrogen compounds and water content in SCBLF affected to increase chlorophyll contents which led improving biomass production (64.67%) and glucose contents (6.07%) than control. Organosolv and dilute acid pretreatments were preliminarily carried for bioethanol production, and the pretreatment processes were conducted at all the same solid to liquid ratio (1 : 10), reaction temperature ($150^{\circ}C$), preheating time (40 min) and residence time (10 min). The water insoluble solid recovery of Organosolv pretreatment with 1% sulfuric acid as a catalyst was the lowest and that of medium treatment plot was 44.81%. Exchangeable cations in SCBLF might be affected to increase pretreatment effect. The simultaneous saccharification and fermentation process was followed to determine the ethanol production of the pretreated biomass. The highest ethanol production yield based on initial weight was obtained from high treatment plotby Organosolv pretreatment with 1% sulfuric acid (16.11%). But regarding biomass production, medium treatment plot produced most, and bioethanol production was increased by 72.93% than control.

• KSBB Journal
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• v.14 no.1
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• pp.51-57
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• 1999

The immobilization of nitrifier consortium was carried out for the application to recirculating aquaculture system(RAS). The abilities of $NH_4^+$-N removal by immobilized nitrifier consortia prepared with boric acid treated, ethanol treated, ad freezing-thawing treated PVA beads at the concentration 15% were examined. To identify the possibility of applying the beads in the fluidized bed reactor, characteristics of beads were evaluated. The suitable bead was boric acid treated beads which had highest ammonia removal rate of 16.09 g/$m^3$/day. It took 12 days for nitrifier consortium immobilized beads to be stable for the removal of $NH_4^+$-N. Life spans of the beads were more than three months with aggressive aeration in the fluidized ed reactor when nitrifier consortia immobilized in PVA beads were used. In order to apply the nitrifier consortium immobilized beads to aquaculture facility, the continuous reactor was used for 49 days with synthetic aquacultural water containing 2 mg/L ammonia. The highest ammonia removal rate of 31.87 g/$m^3$/day was observed when hydraulic residence time was 0.6 hour(36min.).