• 토지주택연구
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• 제8권3호
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• pp.161-169
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• 2017

In this study, sediment transfer and precipitation analysis of the test bed watershed was conducted through the model for the application and practical use of the urban sediment disaster prevention technology, and used this as an aid to design to secure reliability. In addition, conducted the test bed monitoring with the defense technology, analyzed the effect, and established the maintenance plan. Analyzed the change of soil deposition volume through arbitrary slope adjustment for the currently installed stormwater conduit of the test bed watershed. As a result, it is important to reduce the total sedimentation amount in the adjustment of the slope of the entire pipeline, but it is important that the sedimentation depth of each sediment does not rise to such a degree as to threaten the performance of the pipeline. Considering these matters, it is necessary to design the pipeline to prevent the clogging of the soil from the viewpoint of the reliability of the entire pipeline. The sediment disaster defense technology test bed is divided into a new city and an old city, and old city test bed is under construction. The result obtained through the monitoring of the test bed in the new city, sediment disasters such as debris can delay the time to reach the downtown area, and it is possible to secure the golden time, such as evacuation and rescue through the warning system. Also, the maintenance of the test bed application was suggested. Continuous and systematic monitoring is required for securing the reliability of element technology and successful commercialization.

• 한국수자원학회논문집
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• 제44권2호
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• pp.109-123
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• 2011

본 연구에서는 자연하천과 같은 복잡한 지형의 처리에 효율적인 삼각형 및 사각형 혼합격자의 적용이 가능한 2차원 유한체적모형을 개발하였다. 이를 위해 계산격자의 인접격자를 찾는 알고리즘을 제안하고, 제안 기법을 개발모형에 적용하여 계산격자 및 인접격자의 경계면에서의 흐름률을 HLLC 근사 Riemann 해법을 이용하여 계산하였다. 또한 흐름률과 생성항사이의 균형에 중요한 영향을 주는 혼합격자의 하상경사 처리를 위해 삼각형 및 사각형 격자에 대해 각각 다른 하상경사 계산식을 적용하였다. 개발모형을 혼합격자로 구성된 $90^{\circ}$ 만곡이 존재하는 실험하도에 대한 댐 붕괴 해석 및 자연하천인 Malpasset 댐 붕괴 해석에 적용하고, 계산결과를 실험자료 및 현장조사자료와 비교함으로써 본 연구에서 제안한 기법을 실험하도 및 자연하천에 대해 검증하였다.

• 한국수자원학회논문집
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• 제30권6호
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• pp.597-610
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• 1997

본 연구에서는 하도 내에서의 부정류 유사이송으로 인한 하상변동의 일차원적 수치모델들을 개발하였다. 유사량과 하상변동에 대한 수치해를 얻기 위해 흐름의 방정식은 Preissmann 음해법과 Lax-Wendroff 2단 양해법을 그리고 유사의 연속방정식은 시간 전방차분, 공간 중앙차분 양해법을 사용하여 수치 적분하였고, Lax-Wendroff 기법 내에서 상류와 하류의 추가 경계조건을 구하기 위해 특성곡선법을 적용하였다. 모델의 정확도는 부피보존실험을 통하여 성공적으로 입증되었으며, 모델의 주요 변수들에 대한 민감도 분석결과로부터 보다 큰 최대 홍수위, 하상경사 및 홍수지속기간에 의해 큰 하상세굴이 발생하였고, 하상재료의 평균입경 가운데, $D_{50}=0.4mm$에서 가장 큰 하상변동을 가져왔다. 본 연구에서 개발된 모델들이 각 변수들의 변화에 적절한 반응을 함으로써 모델들이 합리적인 결과를 가져다주는 것으로 결론되어지며, 실제하천에 적용될 수 있는 것으로 판단된다.

• 한국환경보건학회지
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• 제19권2호
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• pp.23-33
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• 1993

The anaerobic digestion of organic synthetic wastewater in anaerobic fluidized bed bioreactor (AFBBR) and anaerobic fluidized packed bed bioreactor (AFPBBR) was studied. This study was conducted to evaluate efficiency and reliability of two reactor. Experiment was performed to find the effect of upflow rate with AFBBR and the height of packed bed with AFPBBR. As a result, this program obtained several conclusion. These are given as follows: As applied the upflow rate increased in AFBBR the produced volume of biogas increased, while the gas production and COD removal decreased at above 0.3 m$^3$/h. When a upflow rate is 0.4 m$^3$/h in AFBBR the volatile suspended solid (VSS) became significantly increased. At an organic loading rate from 0.1 to 0.4 of upflow rate in AFBBR, the methane yield was 1.5584 m$^3$CH$_4$/kgCOD removed, and the observed cell yield coefficient was 0.0933 gVSS/gCOD. In case of AFPBBR, the results showed also that 20 cm of height of packed bed was superior to other in the aspect ot biogas production, the content of methane and COD removal. At 20 cm of height, the profile of microorganisms was stable, while at 30 cm the VSS of effluent became higher than AFBBR. Though COD removal of AFPBBR increased with packed bed, COD removal deteriorate with over packing because the loss of pressure became higher in the reactor. At an organic loading rate from 20 to 40 cm of packed bed in-AFPBBR, the methane yield was 2.5649 m$^3$CH$_4$/kgCOD removed, and the observed cell yield coefficient was 0.0506 gVSS/gCOD. Based upon the results obtained, it is suggested that AFBBR and AFPBBR is the most effective conditions at 0.3 m3/h of upflow rate, the 20cm of packed bed, respectively. The rate constant are summarized as follow:

• 한국해양환경ㆍ에너지학회지
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• 제9권2호
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• pp.72-78
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• 2006

혐기성 소화조의 단면적/용량 비를 일정하게 한 상태에서 반응조 직경만을 달리한 반응조에 유기물 부하율에 따른 소화조 운전효율을 평가하였다. $0.4\;kg\;COD/m^3{\cdot}d$의 낮은 유기물 부하율에서는 반응조 직경에 관계없이 높은 처리 효율을 나타내어 반응조 형상에 따른 처리효율 차이는 없었다. $6\;kg\;COD/m^3{\cdot}d$의 유기물 부하율에서는 반응조 직경에 따라 전혀 다른 처리효율이 관측되었다. 즉, 직경 6.4 cm 반응조에서는 휘발성산의 축적과 낮은 COD 제거효율이 관측되었으나 직경 3 cm 반응조에서는 높은 COD 제거효율이 관측되었고 휘발성산의 축적도 일어나지 않았다. 이러한 차이가 나타나게 된 이유는 직경이 작은 반응조의 경우에는 생성된 가스의 부상에 의해 슬러지층의 유동화가 원활하게 일어난데 반해 직경이 큰 반응조의 경우에는 그렇지 못한 것이라고 판단된다. $20\;kg\;COD/m^3{\cdot}d$의 높은 유기물 부하율에서는 반응조 직경과는 관계없이 극히 낮은 처리효율을 나타내어 높은 유기물 부하에서는 반응조 형상과 처리효율과는 관계가 없는 것으로 나타났다. 따라서 혐기성 소화조의 효율적인 start-up은 슬러지층의 유동화가 중요한 인자이며 동일 단면적/용량 비에서 반응조 직경이 작을수록 유리한 것으로 나타나 반응조 형상도 반응조 운전효율에 큰 영향을 미치는 것으로 나타났다.

• Environmental Engineering Research
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• 제23권1호
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• pp.70-75
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• 2018

A pilot scale anaerobic fixed-bed with a reactor volume of $2.8m^3$ was built to treat slaughterhouse wastewater. Bamboo rings were chosen as support media mainly because of their cheaper price in underdeveloped countries. Even with their lower porosity and specific surface, the reactor performance showed a maximum 95% COD removal efficiency at an organic loading rate (OLR) of $1kg\;COD/m^3-d$ with its corresponding hydraulic retention time (HRT) of 7.5 d. At a higher OLR of $4.0kg\;COD/m^3-d$, the COD removal efficiency of 75% was achieved with an HRT of 2 d. No big difference in COD removal efficiencies was found between the reactors operated in both upflow and downflow modes. Their operational behavior and effluent characteristics were similar. The effluent COD/TKN ratio of 6.67 at an OLR of $4.0kg\;COD/m^3-d$ was only marginal acceptable range for a subsequent biological denitrification process. Otherwise carbon supplementation is required at a lower OLR.

• 한국환경과학회지
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• 제12권12호
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• pp.1277-1284
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• 2003

The photocatalytic oxidation of Rhodamine B (RhB) was studied using immobilized TiO$_2$ and fluidized bed reactor. Immobilized TiO$_2$ onto GF/C was employed as the photocatalyst and a 30 W germicidal lamp was used as the light source and the reactor volume was 4.8 L. The effects of parameters such as the amounts of photocatalyst, initial concentration, initial pH, air flow rate and anion additives (NO$_3$$\^$-/, SO$_4$$\^$2-/, Cl$\^$-/, CO$_3$$\^$2-/) competing for reaction. The results showed that the optimum dosage of the immobilized TiO$_2$ was 40.0 g/L. Initial removal rate of immobilized TiO$_2$ was expressed Langmuir - Hinshelwood equation.

• International Journal of Air-Conditioning and Refrigeration
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• 제12권4호
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• pp.198-205
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• 2004

An experimental study was carried on the characteristics of fluid flow and heat transfer in a fluidized bed shell-and-tube type heat exchanger with corrugated tubes. Seven different solid particles having same volume were circulated in the tubes. The effects of vari­ous parameters such as water flow rates, particle geometries and materials, and geometries of corrugated tubes on relative velocities and drag coefficients were investigated. The present work showed that the drag force coefficients of particles in the corrugated tubes were usually lower than those in the smooth tubes, meanwhile the relative velocities between particles and water in the corrugated tubes were little higher than those in the smooth tubes except the particles of glasses.

• 설비공학논문집
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• 제15권5호
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• pp.406-412
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• 2003

An experimental study was carried on the characteristics of fluid flow and heat transfer in a fluidized bed shell-and-tube type heat exchanger with corrugated tubes. Seven different solid particles having same volume were circulated in the tubes. The effects of various parameters such as water flow rates, particle geometries and materials, and geometries of corrugated tubes on relative velocities and drag coefficients were investigated. The present work showed that the drag force coefficients of particles in the corrugated tubes were usually lower than those in the smooth tubes, meanwhile the relative velocities between particles and water in the corrugated tubes were little higher than those in the smooth tubes except the glass.

• 설비공학논문집
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• 제16권12호
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• pp.1149-1155
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• 2004

An experimental study was performed to investigate the characteristics of heat transfer in a vertical type fluidized bed shell-and-tube type heat exchanger with corrugated tube. Seven different solid particles having the same volume were circulated in the heat of exchanger. The effects of various parameters such as water flow rates, particle geometries, materials, and corrugated tube geometries were investigated. The present work showed that the higher thermal capacities of materials and the geometries closer to the spherical one have higher heat transfer performances. In addition, heat transfer coefficients in the corrugated tubes were a little higher than those in the smooth tubes.