• 한국어류학회지
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• 제31권3호
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• pp.165-171
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• 2019

청계천에서 수량이 감소한 이후 2018년 4월부터 10월까지 복원된 구간에서 조사하였다. 수량이 감소되기 전인 2011년에 비해 수심이 지점에 따라 1~5 cm 정도 감소하였다. 출현한 어종은 총 5과 21종이었고 고유종은 몰개 Squalidus japonicus coreanus와 참갈겨니 Zacco koreanus 2종이었다. 2018년에 출현하지 않은 종은 각시붕어 Rhodeus uyekii, 줄납자루 Acheilognathus yamatsutae, 가시납지리 Acheilognathus gracilis, 누치 Hemibarbus labeo, 버들매치 Abbottina rivularis, 끄리 Opsariichthys uncirostris amurensis, 강준치 Erythroculter erythropterus 등 7종이었다. 수량이 감소한 이후 개체수가 급격히 증가한 어종은 피라미 Zacco platypus였으며 개체수 구성비에 있어 24.9%가 증가하였다. 반면 개체수가 급격히 감소한 어종은 버들치 Rhynchocypris oxycephalus (12.3% 감소)와 참갈겨니(13.2% 감소)이었다. 각 조사 지점에서 우점종은 납자루 Acheilognathus yamatsutae (St. 4)와 피라미(St. 1, 2, 3)이었다. 민감종의 개체수는 34.0%에서 8.5%로 감소하였고 내성종은 50.2%에서 75.5%로 증가하였으나 중간종은 변화가 없었다. 충식성종의 개체수는 48.1%에서 19.2%로 급격히 감소하였고 잡식성은 51.6%에서 80.7%로 급격히 증가하였으며 육식성과 초식성은 큰 차이가 없었다. 우점도지수는 0.62에서 0.76으로 증가, 종다양도 지수는 1.80에서 1.33으로 감소, 종균등도 지수는 0.57에서 0.42로 감소, 종풍부도 지수는 3.02에서 2.90으로 감소하였다.

• 한국환경과학회지
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• 제16권6호
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• pp.745-750
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• 2007

Large scale of loess has been applied on the south - sea shore of the Korean peninsula to treat red tides, due to many fishery's devastation by red tides every year. However, coastal ecosystem is ruined by the huge amount of loess applied every year. Almost all creatures, living under water such as sea weeds, clams, and fishes, where loess was applied, are disappearing. In this paper, alternative methods of the loess application are investigated. The amount of loess could be reduced by the alternative methods, Especially, loess mixed with calcium oxide has excellent effects to reduce Cochlodinium polykrikoides numbers. It was found that when loess is used with calcium oxide(CaO), removal efficiency of red tides is highly increased. Moreover, the amount of loess could be reduced dramatically.

• 상하수도학회지
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• 제29권4호
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• pp.447-457
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• 2015

Water cycle within the human civilization has become important with urbanization. To date, water cycle in the eco-system has been the focus in identifying the degree of water cycle in cities, but in practicality, water cycle within the human civilization system is taking on an increasing importance. While in recent years plans to reuse water have been implemented to restore water cycle in cities, the effect that such reuse has on the entire water cycle system has not been analyzed. The analysis on the effect that water reuse has on urban areas needs to be go beyond measuring the cost-savings and look at the changes brought about in the entire city's water cycle system. This study uses a SWAT model and water balance analysis to review the effects that water reuse has on changes occurring in the urban water cycle system by linking the water cycle within the eco-system with that within the human civilization system. The SWAT model to calculate the components of water cycle in the human civilization system showed that similar to measured data, the daily changes and accumulative data can be simulated. When the amount of water reuse increases in urban areas, the surface outflow, amount of sewer discharge and the discharged amount from sewage treatment plants decrease, leading to a change in water cycle within our human civilization system. The determinant coefficients for reduced surface outflow amount and reduced sewer discharge were 0.9164 and 0.9892, respectively, while the determinant coefficient for reduced discharge of sewage treatment plants was 0.9988. This indicates that with an increase in water reuse, surface flow, sewage and discharge from sewage treatment plants all saw a linear reduction.

• 한국토양비료학회지
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• 제35권5호
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• pp.253-263
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• 2002

벼 재배시 시용한 비료와 자재양분의 이동과 흡수에 미치는 영향을 구명하고자 전북통에서 동진벼를 공시하여 2개년간(1999~2000)시험한 결과는 다음과 같다. 시험후 토양의 pH는 생우분 시용구에서 높아졌고 유기물, 인산, 규산, 칼리, 석회, 전질소함량이 증가하였고, 토층내로의 침투수중 무기태질소함량은 $NH_4-N$보다 $NO_3-N$함량이 월등히 많았으며 그 정도는 생우분시용구에서 높았으며, $PO_4-P$함량은 생우분시용구에서 타처리 보다 높았으나 K함량은 표준시비구에서 높았다. 벼 생육기간중 물의 소비량은 477mm였으며, 양분의 공급량과 소비량 중 질소는 무질소구, LCU20%감비구, 무비구에서 공급량보다 소비량이 많았으며, 인산의 경우는 무인산, 무비구를 제외하고는 공급량보다 소비량이 적었다. 또한 칼리는 모든 처리에서 공급량보다 소비량이 많았다. 양분의 침투수 중 시비질소는 진단시비, 표준시비+생우분+규산시용구에서 많았고 수확물의 질소회수율은 LCU20%감비구에서 높았다. 시비인산의 침투율은 생우분시용구에서 많았고, 시비칼리는 LCU20%감비구에서 많았다. 수도체 질소이용율은 LCU20%감비, 인산과 칼리의 이용율은 표준시비+규산시용구에서 높았다. 쌀수량은 진단시비 대비 LCU20%감비>표준시비+규산=표준시비+생우분+규산>표준시비+생우분 순으로 높았다.

• 한국농공학회논문집
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• 제63권3호
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• pp.1-12
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• 2021

Optimal water management is to efficiently and equally supply an appropriate amount of water by using irrigation facilities. Therefore, it is necessary to evaluate water supply capacity through distribution simulation between the designed distribution rate and re-distributed rate according to the changed farming conditions. In this study, we recalculated the agricultural water supply amount of Geumcheon main canal, which beneficiary area was reduced due to the development of Gwangju-Jeonnam innovation city, and we constructed a canal network using the SWMM model to simulate the change in supply rate of each main canal according to the re-distributed rate. Even though the supply amount of the Geumcheon main canal was reduced from 1.20 m³/s to 0.90 m³/s, it showed a similar supply rate to the current, and the reduced quantity could be supplied to the rest of the main canal. As a result, the arrival time at the ends of all main canal, except for the Geumcheon main canal, decreased from 1 to 3 hours, and the supply rate increased from 4 to 17.0% at the main canal located at the end of the beneficiary area of Naju reservoir.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.338-341
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• 2011

Water usage for cleaning the toilet bowl accounts for 27% of the total water usage. Water-saving valve that can select the amount of water for cleaning toilet bowl can be reduced expenditure. After installing water-saving valve, analysed the economic effects. Water-saving valves compared with flush valves, and researched the amount of water usage. Then analyzed fort he economic effects. Water-saving valve was used 5.6 ${\ell}/time$ for cleaning toilet bowl. In contrast, flush valve was consumed 8.4 ${\ell}/time$. Water-saving valve's water-saving rate was 33.3%. The initial payback period for Water-saving valve was 459.5 days. By a small investment in water saving valve, the economic benefits can be obtained.

• 설비공학논문집
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• 제23권10호
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• pp.656-661
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• 2011

The amount of water resources that can be used tend to be decreased gradually. In contrast, the rapidly increasing water consumption is a problem that need to be addressed. Renovation and equipment replacement to improve energy efficiency and to reduce expenditure for building usage is required. But the excessive initial investment cost and the prolonged of pay back period may be uneconomical choice. Water usage for cleaning the toilet bowl accounts for 27%of the total water usage. Water-saving valve that can select the amount of water for cleaning toilet bowl can be reduced expenditure. After installing water-saving valve, analysed the economic effects. Water-saving valves compared with flush valves, and researched the amount of water usage. Then analyzed for the economic effects. Water-saving valve was used 5.6 ${\ell}$/time for cleaning toilet bowl. In contrast, flush valve was consumed 8.4 ${\ell}$/time. Water-saving valve's water-saving rate was 33.3%. The initial payback period for Water-saving valve was 459.5 days. By a small investment in water saving valve, the economic benefits can be obtained.

• 한국분무공학회지
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• 제28권1호
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• pp.43-48
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• 2023

The waste-heat-recovery boiler with water spray (HR-B/WS) applies the heat exchange between the inlet air and exhaust gas with the water spray into the inlet air. The evaporation of water in the inlet air promotes heat recovery from the exhaust gas so that thermal efficiency can be improved by the enhanced condensing effect. The NOx emission can also be reduced by lowering the flame temperature due to the dilution effect of the water. In this study, the validity of this concept is examined by the practical boiler test performed with a 24 kW condensing boiler under the full load condition according to the water injection amount. The theoretical amount of water injection is calculated under the assumption of full evaporation of the sprayed water, which is calculated as 50 g/min. Since the injected water cannot evaporate fully in the actual system, the maximum water spray amount is set as 100 g/min. The results showed that the water injection can increase the thermal efficiency up to 95.59% and reduce NOx and CO emissions simultaneously to 8.9 ppm and 35 ppm at 0% of O₂. Although the heat energy loss increased due to the unevaporated water, the increase in water injection amount caused higher thermal efficiency due to the increased amount of the evaporated water.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.148.2-148.2
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• 2013

We prepared hydrophobic PDMS-coated porous silica as pre-concentration adsorbent for chemical warfare agents (CWAs). Since CWAs can be harmful to human even with a small amount, detecting low-concentration CWAs has been attracting attention in defense development. Porous silica is one of the promising candidates for CWAs pre-concentration adsorbent since it is thermally stable and its surface area is sufficiently high. A drawback of silica is that adsorption of CWAs can be significantly reduced due to competitive adsorption with water molecule in air since silica is quite hydrophilic. In order to solve this problem, hydrophobic polydimethylsiloxane (PDMS) thin film was deposited on silica. Adsorption and desorption of chemical warfare agent (CWA) simulants (Dimethylmethylphosphonate, DMMP and Dipropylene Glycol Methyl Ether, DPGEM) on bare and PDMS-coated silica were studied using temperature programed desorption (TPD) with and without co-exposing of water vapor. Without exposure of water vapor, desorbed amount of DMMP from PDMS-coated silica was twice larger than that from bare silica. When the samples were exposed to DMMP and water vapor at the same time, no DMMP was desorbed from bare silica due to competitive adsorption with water. On the other hand, desorbed DMMP was detected from PDMS-coated silica with reduced amount compared to that from the sample without water vapor exposure. Adsorption and desorption of DPGME with and without water vapor exposing was also investigated. In case of bare silica, all the adsorbed DPGME was decomposed during the heating process whereas molecular DPGME was observed on PDMS-coated silica. In summary, we showed that hydrophobic PDMS-coating can enhance the adsorption selectivity toward DMMP under humid condition and PDMS-coating also can have positive effect on molecular desorption of DPGME. Therefore we propose PDMS-coated silica could be an adequate adsorbent for CWAs pre-concentration under practical condition.

• 한국태양에너지학회 논문집
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• 제34권6호
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• pp.11-18
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• 2014

Two-step water splitting thermochemical cycle with $CeO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2$ foam device depending on reaction temperature of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. As a result, the amount of reduced $CeO_2$ considerably varies according to the reaction temperature of Thermal-Reduction step. and hydrogen production was not much when the amount of reduced $CeO_2$ decreased even if the reaction temperature of Water-Decomposition step was high. Therefore, it is very important to keep the reaction temperature of Thermal-Reduction step high in two-step thermochemical cycle with $CeO_2$.