• Resources Recycling
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• v.8 no.1
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• pp.18-22
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• 1999

In order to utilize incineration fly ash of industrial wastes as resources, we present the recovery and separation of metals included in the fly ash by leaching with aqueous solution A great quantity of Cu, Pb, and Zn as well as a small amount oftoxic heavy metals are contained in the leach liquor of the fly ash, and the concentration of the ingredients of the fly ash depends on the industrial wastes which are fed into incinerators. In this paper, sequential Ieachiog operations are conducted using $H_2O$, $H_2SO_4$, $(NH_4)_2CO_3$ and NaOH as Icachants. Water soluble copper salt was leached by $H_2O$, Zn and Pb were separated by the NaOH leach liquor, and water insoluble copper was selectively leached as chelate ion with the $(NH_4)_2CO_3$ leach liquor of the third Ieaehant. Results show that the reduction percent of the fly ash in the leaching steps using $H_2O$, $H_2SO_4$, and $(NH_4)_2CO_3$ is 77%, and the other leaching procedures lose the weight of fly ash by above 60%.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.119-128
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• 2020

An ultrasonic multiple scattering simulation using cross-section of fine dust particles were proposed. These days, along with awareness of air pollution, social interest in fine dust is increasing. In the construction field, awareness of fine dust is increasing, and research on preparing various countermeasures is underway. The light scattering method fine dust meter currently in use is affected by environmental factors such as relative humidity, and reliability problems in terms of accuracy are continuously reported. However, the transmission of ultrasonic waves can directly reflect the physical change of the medium based on the mechanical wave. Using these advantages of ultrasonic waves, fine dust measurement simulation was performed using the scattering cross section and ultrasonic multiple scattering theory. The shape data of the fine dust particles were collected using a SEM (Scanning Electron Microscope), and a cross-section according to the fine dust particles was derived through numerical analysis. As a result of signal processing, the error for the number density corresponding to each cross-section is minimum 19, maximum 3455.

• Journal of Korean Society of Forest Science
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• v.57 no.1
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• pp.14-19
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• 1982

Fines in high-yield sulfite pulp have much higher water retention value as compared with fines in Stone groundwood pulp. Therefore, they are apt to adhere partially or entirely onto the fiber surface during the paper making. This tendency is greatly enhance with decrease of the pretreated yield and increase of the water retention value of fines. Fines, which adhere onto the fiber surface in paper, contribute to the light scattering of the paper. Accordingly, the specific scattering coefficient of fines in high-yield sulfite pulp is considerably lower than that of fines in stone groundwood pulp, which hardly adhere onto the fiber surface. The fact that high-yield sulfite pulp is inferior to stone groundwood pulp in opacity is explained on the basis of the high degree of swelling of fined in addition to the softening of fiber fraction.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.790-795
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• 1997

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuransfurans are the archetype of toxic chemicals. So it has absorbed public attention. The majors primary sources of PCDDS and PCDFs are chemical, thermal and photochemical reactions. Municipal solid waste incinerator facilities has been reported as the major contributors of dioxins to the environment. In this paper, Dioxins and furans were examined emission gas and fly ash produced during combustion in municipal solid waste incinerator. More effective method for sampling, extraction was described. The sample was extracted using a soxhlet method and purified using silicagel, alumina and carbon fibre HPLC to remove interfering compound. The extract was then analyzed by HRGC/HRMS. The result of this study showed recovery standard was good and the data resembled those of thermal processes. Total dioxins and furans were $1076.20pg/Nm^3$ and $1452.34pg/Nm^3$ respectively. The amount of highly chlorinated compound was more than that of lowly chlorinated compound. The 2,3,7,8-substituted TCDD was Just 0.34% of the total dioxins/furans amount.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.60-66
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• 2002

본 연구는 진동형 구기자 수확기를 개발함에 있어서 탈과된 열매를 손상없이 집과하여 수확작업의 노동력 및 경제적 비용을 줄이고, 농산물 수확의 기계화를 활성화 시키는데 그 목적을 두었다. 생물학적, 재배학적, 그리고 환경적 요인들을 고려하여 탈과열매의 효과적인 집과를 위한 집과장치를 설계·개발하고, 성능시험을 실시하여 집과장치의 집과효율을 분석 하였으며, 그 결과는 다음과 같다. 1. 수확시작기의 주행시에는 집과안내장치가 구기자 나무 밑부분과 부딪침이 없고, 탈과작업시에는 구기자 나무 밑의 공간까지 집과기능을 갖도록, 4절 링크 시스템을 이용하여 집과 안내장치를 개폐식으로 설계제작하였다. 2. 개폐식으로 제작된 집과장치를 진동형 구기자 수확기 시작기에 장착하여 성능시험을 한 결과, 숙과의 수집율은 88∼96%로 나타났다. 3. 미수집율인 4∼12%는 개폐식 집과장치의 기능저하로 인하여 발생한 것이 아니고, 기계전후 방향의 열매의 튐 현상에 의한 것이었으며, 이 손실은 비산방지막 커튼의 설치로 보완되리라 사료되었다.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.84-84
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• 2019

산채류의 종자 및 종묘는 시중 거래가격이 높게 형성되어 재배농가의 경영비 증가로 이어지고 있다. 특히 산채 꾸러미에 분류되는 작물 중 개미취(Aster tataricus), 섬쑥부쟁이(Aster glehnii ), 우산나물(Syneilesis palmata)은 주로 종묘의 형태로 공급되어 수급이 안정치 못하다. 이에 본시험은 개미취, 섬쑥부쟁이, 우산나물의 우량종자 생산을 위한 종자 결실률 향상 재배조건과 채종적기를 구명하고자 하였다. 시험작목을 전북 남원시 허브산채시험장에서 2016년 4월에 종묘를 노지에 정식하였다. 적정 채종 재배조건을 구명하기 위해 2018년 노지, 하우스, 55% 차광막을 설치한 처리구별 각 작물의 개화시기, 개화율, 생육특성, 결실률 등을 조사하였다. 또한 채종적기를 설정하기 위해서 각 작물별 개화 후 50일, 70일, 90일, 110일, 130일 간격으로 채종하여 결실률과 종자 발아율을 조사하였다. 개화가 시작된 일자는 개미취의 경우 하우스재배, 노지재배, 차광재배 순으로 빨랐으며 섬쑥부쟁이는 노지재배에서 개화시기가 가장 늦었다. 모든 작물의 개화가 종료되는 시점은 처리 간 차이가 없었다. 개화율은 개미취와 섬쑥부쟁이는 노지재배, 하우스재배, 차광재배 순으로 많았으며 우산나물은 노지재배시 개화율이 9.3%로 매우 낮았다. 개화기 생육특성을 조사한 결과 개미취는 초장과 엽폭이 차광재배, 하우스재배, 노지재배 순으로 커지는 경향이었으며, 섬쑥부쟁이는 하우스 재배에서 타 재배방법에 비해 우수하였다. 우산나물은 차광재배에서 생육이 가장 좋았다. 결실률은 개미취와 섬쑥부쟁이는 재배방법에 상관없이 결실률이 60%이상이었다. 반면 우산나물은 평균 31%로 타작물에 비해 상대적으로 결실률이 낮았으며 차광 재배일 때 43%로 가장 결실률이 좋았다. 개미취는 개화 50일 이후부터 종자 결실률이 65%이상으로 높았으며, 섬쑥부쟁이의 결실률은 개화 후 50일이 가장 좋았으며, 그 이후로 점차 결실률이 떨어지는 경향이었다. 우산나물은 개화 후 90~110일경에 가장 결실률이 높은 경향이었다. 개미취는 개화 후 70일일 때 가장 발아율이 낮았으며, 90일일 때 가장 발아율이 좋았다. 섬쑥부쟁이의 발아율은 개화 50일 이후부터 최종 채종시기까지 80%이상으로 우수하였다. 우산나물은 채종시기에 따라 발아율 정도가 매우 상이하여, 채종시기가 늦어질수록 발아율이 높아졌다. 따라서 개미취는 하우스 재배를 통해 개화 후 90일 때 채종하는 것이 가장 발아율이 좋았으며, 섬쑥부쟁이는 차광재배일 경우 개화 50일 이후에는 발아율이 90% 이상이므로 이때부터 종자비산 전까지가 채종적기로 판단된다. 우산나물은 타작물에 비해 다소 결실률이 떨어지나 차광재배 시 개화 110일 후 우량종자를 채종할 수 있을 것으로 여겨진다.

• The Journal of Engineering Geology
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• v.21 no.3
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• pp.231-237
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• 2011

An active apatite drainage system has been developed at the Goro abandoned mine, comprising a grit cell, a reaction cell, and a precipitation pond. Leachate from an abandoned adit and tailing ponds is collected in a pipeline and is transported to the apatite drainage system under the influence of the hydraulic gradient. The results of a laboratory experiment performed in 2004 indicate that the reaction cell requires 38.8 ton/year of apatite and that precipitate will have to be removed from the precipitation pond every 3 months. The purpose of this study is to evaluate a laboratory test on the efficiency of limestone and apatite in removing arsenic from ARD (acid rock drainage), and to evaluate the suitability of materials for use as a precipitant for the leachate treatment disposal system. The laboratory tests show that the arsenic removal ratios of limestone and apatite are 67.4%-98.3%, and the arsenic removal ratio of apatite is inversely proportional to its grain size. The arsenic compounds are assumed to be Johnbaumnite and Ca-arsenic hydrate. Therefore, apatite and phosphorous limestone can be used as a precipitant for the removal of arsenic, although it is difficult to remove arsenic from ARD when it occurs in low concentrations.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1186-1192
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• 2005

The relationship between bacteria and anaerobic archaea, sludge yield coefficient and nitrogen removal rate were investigated in intermittent aeration systems(I/A) with added archaea, I/A and conventional activated sludge system. As the archaea solution was added to the I/A reactor, organic removal rate as well as nitrogen removal rate increased. Also, sludge production rate in I/A system added the archaea was maintained lower than other systems because sludge yield coefficient was decreased due to the role of anaerobic archaea such as anaerobic degradation of organics. The experimental data supported the possibility of symbiotic activated sludge system with anaerobic archaea under intermittent aeration, leading to the enhanced nitrogen removal. Crucial results to be presented are: 1) specific oxygen utilization rate(SOUR) of the I/A-arch system was $2.9\;mg-O_2/(g-VSS{\cdot}min)$. SOUR and nitrification rate of the sludge from the I/A-arch system was higher than those from the I/A and A/S reactors. 2) Removal efficiencies of $TCOD_{Cr}$ in the I/A-arch, I/A and A/S reactors were 93, 90 and 87%, respectively. 3) Nitrification occurred successfully in each reactor, while denitrification rate was much higher in the I/A-arch reactor. Efficiencies of TN removal in the I/A-arch, I/A and A/S reactors were 75, 63 and 33%, respectively.

• Fire Science and Engineering
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• v.20 no.2 s.62
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• pp.80-86
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• 2006

This study focuses on spalling phenomenon which is the one of the main issues of high strength concrete. The definition, classification and characterization, causes and the reaction mechanism of the spalling were investigated on the basis of previous literatures. The spalling phenomenon occurs when several factors such as sharp temperature increase, high water content, low water/cement ratio and local stress concentration in material combine in the concrete material. On the basis o f the factors, the preventing methods from the spalling are known as decrease of temperature increase, preventing of concrete fragmentation and fast drying of internal moisture. In this study, the controlling method of water content below some critical value was proposed as the most effective spalling-preventing method among the spalling-preventing methods. The spalling phenomenon can be prevented by adjusting the water content in the high strength concrete. Therefore, an enforced drying method is needed to decrease the water content below a critical value. Additional experimental data should be generated to determine the critical value of water content for preventing the spalling.

• Journal of Korean Society of Forest Science
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• v.85 no.1
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• pp.66-75
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• 1996

This study was carried out to examine the forest fire effect on water storage characteristics in the forests. Water storage capacity of the burned area was analyzed by several major factors, such as soil pore, maximum water content, effective water storage, and percolation rate. The results obtained from the analysis of major factors are as follows; The deeper soil depth, the less total pore, coarse pore, effective water storage, and percolation rate. However, fine pore increased slightly in both burned area and control plot. As compared with control plot, burned area showed lower percolation rate, coarse pore, and effective water storage, but higher values of fine pore. Directly after forest fire, the soil pore is little affected. But as the time passes, top soil structure changes and soil pore also is affected even in a deep soil. Estimated effective water storage was lower at top soil of Namcheon and at deep soil of Namha in all the burned areas, but slowly decreased in deep soil compared to control plots. Therefore it was concluded that forest water storage capacity was greatly affected by the forest fire.