• 한국물환경학회지
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• 제21권2호
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• pp.147-152
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• 2005

Fermentation efficiencies of organic wastes from the variety of sources were evaluated based on the production of total volatile acids(TVA) in batch reactor. Mixing and pH were not significant factors in producing TVA from the organic wastes. After a 10-day fermentation, final TVA concentrations in piggery, cattle, poultry, and primary settled sludge of domestic wastewater were 8,900, 2,900, 7,370 and 1,630 mg/L, respectively. The pH of organic wastes was decreased from neutral to 5.7. The ratio of TVA to $NH_4{^+}-N$ produced from the animal waste ranged from 11.5 to 30.1, whereas, that in the primary settled sludge of domestic wastewater, was 5.4. Possibility of fermented organic wastes as the electron donors for denitrification in the activated sludge was investigated. In both acclimated and nonacclimated activated sludge, higher denitrification rates were obtained with fermented piggery sludge added than with either methanol or acetate added. The fermented organic acids derived from the primary settled sludge gave the higher denitrification rate ($4.2mg\;NO_3-N/g\;vss{\cdot}hr$) in the acclimated activated sludge. Denitrification rate was $1.5mg\;NO_3-N/g\;vss{\cdot}hr$ in the nonacclimated sludge with the fermented acids from the primary settled sludge of domestic wastewater added.

• Geomechanics and Engineering
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• 제32권3호
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• pp.245-254
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• 2023

Through qualitative analysis and quantitative analysis, the contradictory conclusions about the stability of the settled goaf with two-layer coal seams subject to building load were obtained. Therefore, it is necessary to combine the additional stress method and numerical simulation to further analyze the foundation stability. Through borehole analysis and empirical formula analogy, the height of water-conducting fracture zone in No.4 coal and No.9 coal were obtained, providing the calculation range of water-conducting fracture zone for numerical simulation. To ensure the accuracy of the elastic modulus of broken gangue, the stress-strain curve were obtained by broken gangue compression test in dried state of No.4 coal seam and in soaking state of No.9 coal seam. To ensure the rationality of the numerical simulation results, the actual measured subsidence data were retrieved by numerical simulation. FISH language was used to analyze the maximum building load on the surface and determine the influence depth of building load on the foundation. The critical building load was 0.16 MPa of No.4 settled goaf and was 1.6 MPa of No.9 settled goaf. The additional stress affected the water-conducting fracture zone obviously, resulted in the subsidence of water-conducting fracture zone was greater than that of bending subsidence zone. In this paper, the additional stress method was analyzed by numerical simulation method, which can provide a new analysis method for the treatment and utilization of the settled goaf.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1786-1792
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• 2011

If the concrete track is settled excessively, it must be restored or reinforced immediately. Especially, reinforcement/restoration method should be applied without affecting on train operation. To deal with this problem, special equipment, process and material should be prepared. This paper suggest a special mixing ratio to restore the settled concrete track. Materials are classified the quick hardening mortar and the middle hardening mortar. The quick hardening mortar is used to restore the settled track and the middle hardening mortar is used to fill the void. These materials must have the appropriate gel time(1-40sec) and compressive strength($5kg/cm^2$). Various compounds is used and the micro cement is used as a main base.

• 자원ㆍ환경경제연구
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• 제10권2호
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• pp.259-279
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• 2001

This paper investigates the optimal ratio of the ex post cost settled in the total cost paid to the facility-operating agent and the size of compensation for demand promotion efforts made by the trustee. We have extended McAfee and McMillan(1986)'s principal-agent model by incorporating incentives for the demand promotion efforts. We show that cost reducing effort is negatively related with the ratio of the ex post cost settled in the total cost. In addition, the optimal level of demand promotion effort is determined by the size of the compensation and the ratio of the ex post cost settled. A simulation study confirms our findings from a theoretical model.

• 상하수도학회지
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• 제23권2호
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• pp.231-239
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• 2009

The purpose of this research is to provide more reliable water unit factors of domestic airports by investigating of general informations related to the domestic airport. The informations of domestic airports such as passengers, settled population of airports, building areas and water amount are investigated to estimate the unit factor of water of domestic airports. The domestic airports are divided into three type such as central airport, position airport and general airport. Through analysis of relationship between water amount and the others, the unit factor of water could be calculated. The water amount of central airport as Incheon international airport and position airports could be estimated by unit factor of settled population. The others could be estimated by unit factor of building area.

• 한국철도학회논문집
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• 제10권3호
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• pp.296-305
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• 2007

A numerical method for the analysis of train/slab-track interaction on the settled roadbed is developed based on the already developed analysis method of train/ballast-track interaction. The concrete slabs composed of the upper track concrete layer and the lower hydraulic bonded layer are modelled by a equivalent beam. The supporting stiffness of roadbed is evaluated with the modified boussinesq method suggested by Eisenmann. The track irregularity and the gap between slab and roadbed induced by settlement of roadbed are calculated by the effective method newly presented in this study. The validation of the developed method is investigated by a numerical example. The effects of train speed on train and slab track on the settled roadbed with sinusoidal shape of wave length 20m and amplitude 20mm are reviewed.

• 과학기술학연구
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• 제18권1호
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• pp.129-175
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• 2018

이 논문은 한국석면운동의 지식 정치적 측면을 검토한다. 2008년 본격적으로 시작된 석면운동은 석면오염을 한국 사회의 중요한 안전보건의제로 만드는 데 앞장서 왔다. 석면오염 측정은 특히 석면오염이 광범위하고 심각한 환경보건문제라는 주요 주장을 펼치는 데 매우 중요했다. 이 활동의 특징은 공정시험방법이 아닌 '먼지 분석법'을 활용했다는 것이다. 이 논문에서는 석면운동가들의 오염 조사 보고서와 삼성 본관 주변 석면오염 논란을 통해 먼지 분석법이 대항 지식으로서 권력을 획득하는 과정을 분석한다. 석면운동가들은 먼지 분석으로 얻은 측정 데이터를 활용해 그들의 주장에 언론의 이목을 집중시키고, 정책적 변화에 필요한 자원을 동원할 수 있었다. 그러나 규제기관을 중심으로 한 전문가 집단은 먼지 분석법이 신뢰할 수 있는 석면오염 측정방법이라는 석면운동가들의 주장에 동의하지 않았다. 이와 같은 결론을 내리는 데 측정 과정에서 표준적 방법의 사용 여부와 측정 데이터의 해석적 맥락이 중요한 기준으로 작용하였다. 먼지 분석법의 권위는 부분적으로 획득되었다. 그러나 먼지 분석법은 규제과학이 내포하는 가정들을 드러내고 사회적 토론의 대상으로 전환시켰다는 점에서, 사회 운동과 과학을 결합하여 규제기관과 전문가 집단의 측정에 도전한 석면운동의 특성을 잘 보여준다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.230-233
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• 2006

Conventionally, it used to be focused on simply prevention of further settlement of structures, where, much of problems were raised and sometimes the construction itself was not possible. Further, rough estimation of the ground, which is unseen, often incurred many troubles in the maintenance. D-ROG method is a high-tech technology that changes almost all of the concepts on the conventional grouting, is expanding its application scope spanning from the restoration of settled structures to ground strengthening works necessary for building enlargement and remodeling.

• 한국물환경학회지
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• 제20권1호
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• pp.18-23
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• 2004

In this research, a 2-stage intermittently aerated activated sludge system(IA) and intermittently aerated dynamic flow activated sludge system(DF) were investigated for the removal of nutrients in domestic wastewater. Wastewater was characterized by low C/N( organics/nitrogen) ratio. $COD_{cr}$, $BOD_s$, TKN and TP concentrations of domestic wastewater were 235, 47, 32 and 5.4 mg/L, respectively. Three sets of IA and one set of DF were operated. Three of four systems were added with fermented settled sludge taken from primary settling tank as an external electron donor and the other(IA) for control reactor was operated without addition of electron donor. All systems were operated at same sludge retention time of 20 days and hydraulic retention time of 12hrs. The supplemental electron donor was supplied into the anoxic mode. A higher denitrification rate was observed from the reactors with fermented settled sludge as an electron donor for denitrification compared to that of without addition of organic source. The result of this study indicates that the settled primary sludge, if the fermented at the acid stage, was an excellent electron donor for denitrification. 81 % of TN and 80% of TP were removed from the systems with the supplemental organic source added. However, the control reactor without addition of electron donor showed only 39% of TN and 43% of TP.

• 한국양식학회지
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• 제13권2호
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• pp.153-161
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• 2000

10종의 부착성 규조류를 대상으로 참전복 치패의 먹이효율을 조사하였다. 유생의 부착율을 실험 1에서 Rhaphoneis sp.가 31.6%, 실험 2에서는 P. tricornutum가 16.4%로 가장 높았다. 부착성 규조류를 먹이로 한 치패의 생존율은 실험1에서 Raphoneis sp.가 62.7%로 가장 높았고, N. incerta, C. schroderi, N. closterium 는 각각 56.8%, 55.2%, 54.3%로 비교적 높았으며, Navicula sp. (B-38)는 30.5%로 가장 낮았다. 그리고 실험 2와 3에서는 C. schroderi, N. incerta, P. tricornutum 및 Raphoneis sp.는 높은 생존율을 보였으며, 특히 C. schroderi는 67.6%, 49.4%로 가장 높았다. 반면, H. marina (40.4%, 15.7%), Nitzschia sp. (39.1%, 27.1%), N. closterium (35.2%, 18.0%)은 비교적 낮았다. 치패의 성장에 있어서 일간성장량은 부착율과 생존율이 높았던 C. schroderi에서 최고 83.3 ${\mu}$m로 가장 높았고, 생존율이 낮았던 H. marina와 N. closterium은 19.9~38.7 ${\mu}$m로 가장 낮은 일간성장량을 보였다.