폐기물매립지에서의 온실가스 발생량 예측 모델 및 변수 산정방법 개발

박진규(Park, Jin-Kyu),강정희(Kang, Jeong-Hee),반종기(Ban, Jong-ki),이남훈(Lee, Nam-Hoon) 대한토목학회 2012 대한토목학회논문집 B Vol.32 No.6B

본 연구의 목적은 폐기물매립지에서의 온실가스 발생량 예측모델 및 모델에 적용된 변수들의 산정방법을 개발하는 것이다. 본 연구에서는 온실가스 발생예측 모델 중 1차 반응모델의 변수인 메탄잠재발생량과 메탄발생속도상수를 평가하기 위하여 수정 Gompertz 식과 Logistic 식을 미분한 2개의 식을 적용하였다. 변수들은 실제 폐기물매립지에서의 매립가스 발생량에 대한 실측값과 예측값과의 통계학적 비교를 통해 산정하였다. 매립가스 발생량에 대한 실측값과 수정 Gompertz 식 및 Logistic 식을 미분하여 나타낸 2개의 식을 이용한 매립가스 발생량 예측값에 대한 회귀분석결과 결정계수는 각각 0.92와 0.94로 나타나, 폐기물매립지에서의 매립가스 발생량에 대한 측정값이 있을 경우 회귀분석을 통해 변수를 산정할 수 있는 것으로 나타났다. 또한 실측값이 없는 폐기물매립지에서의 온실가스 발생량을 예측할 수 있도록 하기 위하여 수정 Gompertz 식과 Logistic 식을 미분한 2개의 식을 기초로 하여 예측모델을 개발하였으며, 이 모델들의 정확성을 평가하기 위하여 Qcs(실측값):Q(예측값)의 비에 대한 빈도분포를 평가한 결과 LandGEM 모델보다 높은 정확성을 나타내었다. 따라서 본 연구에서 개발한 모델들은 폐기물매립지에서의 온실가스 발생량 예측에 적합한 것으로 사료된다. The objective of this research is to develop greenhouse gas generation models and estimation method of their parameters for solid waste landfills. Two models obtained by differentiating the Modified Gompertz and Logistic models were employed to evaluate two parameters of a first-order decay model, methane generation potential (L0) and methane generation rate constant (k). The parameters were determined by the statistical comparison of predicted gas generation rate data using the two models and actual landfill gas collection data. The values of r-square obtained from regression analysis between two data showed that one model by differentiating the Modified Gompetz was 0.92 and the other model by differentiating the Logistic was 0.94. From this result, the estimation methods showed that L0 and k values can be determined by regression analysis if landfill gas collection data are available. Also, new models based on two models obtained by differentiating the Modified Gompertz and Logistic models were developed to predict greenhouse gas generation from solid waste landfills that actual landfill generation data could not be available. They showed better prediction than LandGEM model. Frequency distribution of the ratio of Qcs (LFG collection system) to Q (prediction value) was used to evaluate the accuracy of the models. The new models showed higher accuracy than LandGEM model. Thus, it is concluded that the models developed in this research are suitable for the prediction of greenhouse gas generation from solid waste landfills.

B-Rep Solid 구조의 3차원 모델을 이용한 토공량 자동 산정에 관한 연구

김종남,엄대용 한국측량학회 2022 한국측량학회지 Vol.40 No.5

As the 4th industrial revolution is in full swing and next-generation ICT(Information & Communications Technology) convergence technology is being developed, various smart construction technologies are being rapidly introduced in the construction field to respond to technological changes. In particular, since the earth-volume calculation process for site design accounts for a large part of the design cost at the construction site, related researches are being actively conducted to improve the efficiency of the process and accurately calculate the earth-volume. The purpose of this study is to present a method for quickly constructing the topography of a construction site in 3D and efficiently calculating earth-volume using the results. For this purpose, the construction site was constructed as a 3D realistic model using large-scale aerial photos obtained from UAV(Unmanned Aerial Vehicle). At this time, since the constructed 3D realistic model has a surface model structure in which volume calculation is impossible, the structure was converted into a 3D solid model to enable volume calculation. And we devised a methodology to calculate earth-volume based on CAD(Computer-Aided Design and Drafting) using the converted solid model. Automatically calculating earth-volume from the solid model by applying the method. As a result, It was possible to confirm a relative deviation of 1.52% from the calculated earth-volume from the existing survey results. In addition, as a result of comparative analysis of the process time required for each method, it was confirmed that the time required is reduced of 60%. The technique presented in this study is expected to be utilized as a technology for smart construction management, such as periodic site monitoring throughout the entire construction process, as well as cost reduction for earth-volume calculation. 최근 4차 산업혁명이 본격화되고 차세대 ICT 융합 기술이 개발됨에 따라 건설분야 역시 기술변화에 대응하기 위 해 다양한 스마트 건설기술이 건설 단계별로 빠르게 도입되고 있다. 특히, 건설현장의 경우 부지설계를 위한 토공량 산출 공정이 설계비용에 큰 부분을 차지하고 있어 공정의 효율화와 정확한 토공량 산출을 위한 관련 연구가 활발히 진행되고 있다. 본 연구는 건설현장의 지형을 3차원으로 신속하게 구축하고 이를 이용하여 효율적으로 토공량을 산 출할 수 있는 방법을 제시하고자 한 것이다. 이를 위해 무인비행체로부터 획득한 대축척의 항공사진을 이용하여 건 설현장을 3차원 실사모델로 구축하다. 이때, 구축한 3차원 실사모델은 체적 산출이 불가한 surface 모델 구조를 가 짐에 따라 체적 산출이 가능하도록 3차원의 solid 모델로 구조 변환을 수행하다. 그리고 변환된 solid 모델을 이용 하여 CAD 기반으로 토공량을 산출할 수 있는 방법론을 구상하다. 정립한 방법론을 적용한 solid 모델로부터 토 공량을 자동 산출한 결과, 기존의 현황측량 결과로부터 산출한 토공량과 1.52%의 상대적 편차를 확인할 수 있었다. 추가적으로 방법별 공정 소요시간을 비교분석한 결과 60%의 소요시간 절감을 확인할 수 있었다. 이로부터 본 연구 에서 제시한 기법은 토공량 산출을 위한 비용절감은 물론 건설공사 전 공정에서 주기적인 현장의 모니터링 등 스마 트 건설관리를 위한 기술로써 활용이 기대된다.

Progressive Solid Model Representation and Transmission : 프로그레시브 솔리드 모델의 표현 및 인터넷 전송

이재열(Jae Yeol Lee),이주행(Joo-Haeng Lee),김현(Hyun Kim),김형선(Hyung Sun Kim) 한국산업경영시스템학회 2002 한국산업경영시스템학회 학술대회 Vol.2002 No.추계

Progressive mesh representation and generation have become one of the most important issues in network-based computer graphics. However, current researches are mostly focused on triangular mesh models. On the other hand, solid models are widely used in industry and are applied to advanced applications such as product design and virtual assembly. Moreover, as the demand to share and transmit these solid models over the network is emerging, the representation and the generation of progressive solid models depending on specific engineering needs and purpose are essential. In this paper, we present a Cellular Topology-based approach to generating progressive solid models from a feature-based solid model. The proposed approach introduces a new scheme for storing and transmitting solid models over the network. The Cellular Topology approach makes it possible to effectively generate progressive solid models and to efficiently transmit the models over the network.

Automatic simplification of solid models for engineering analysis independent of modeling sequences

우윤환 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.7

Although solid models can represent complex and detailed geometry of parts, it is often necessary to simplify solid models by removing the detailed geometry in some applications such as finite element analysis and similarity assessment of CAD models. There are no standards for judging the goodness of a simplification method, but one essential criterion would be that it should generate a consistent and acceptable simplification for the same solid model, regardless of how the solid model has been created. Since a design-feature-based approach is tightly dependent on modeling sequences and designer’s modeling preferences, it sometimes produces inconsistent and unacceptable simplifications. In this paper, a new method is proposed to simplify solid models of machined parts. Independently of user-specified design features, this method directly recognizes and generates subtractive features from the final model of the part, and then simplifies the solid model by removing the detailed geometry by using these subtractive features.

프로그레시브 솔리드 모델의 표현 및 인터넷 전송

이재열,이주행,김현,김형선 한국산업경영시스템학회 2002 한국산업경영시스템학회 학술대회 Vol.2002 No.추계

Progressive mesh representation and generation have become one of the most important issues in network-based computer graphics. However, current researches are mostly focused on triangular mesh models. On the other hand, solid models are widely used in industry and are applied to advanced applications such as product design and virtual assembly. Moreover, as the demand to share and transmit these solid models over the network is emerging, the representation and the generation of progressive solid models depending on specific engineering needs and purpose are essential. In this paper, we present a Cellular Topology-based approach to generating progressive solid models from a feature-based solid model. The proposed approach introduces a new scheme for storing and transmitting solid models over the network. The Cellular Topology approach makes it possible to effectively generate progressive solid models and to efficiently transmit the models over the network.

Flux model for the membrane distillation process to treat wastewater: Effect of solids concentration

Kim, Seunghwan,Kim, Sewoon,Ahmed, Zubair,Cha, Daniel K.,Cho, Jinwoo Elsevier 2018 Journal of membrane science Vol.566 No.-

<P><B>Abstract</B></P> <P>This study aims to develop a mathematical model to estimate the initial permeate flux of a direct contact membrane distillation process operated with various solids concentrations and Cross Flow Velocities (CFVs). Digestate produced from an anaerobic digestion of livestock wastewater was used as a feed solution for the laboratory scale membrane distillation. Heat transfer coefficients and Nusselt number constants were determined from the distillation experiments performed with various CFVs and feed solution temperatures. An empirical function was derived to reflect the effect of solids concentration on the flux prediction. A statistical analysis supported that the flux predicted by the model fitted very well with the observed flux. By using the developed model, numerical experiments were performed to simulate the flux according to various CFVs, feed solution temperatures, and solids concentrations (0–2200 mg/L). Also, Temperature Polarization Coefficient (TPC) values were calculated by using the results simulated from the numerical experiments. The developed model can be used to predict the initial flux of the membrane distillation process specifically to treat wastewater including high solids contents, and the modeling works can provide more insights on the relationship among flux, CFV, temperature difference, solids concentrations, and heat transfer efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A mathematical model developed to predict the permeate flux of the DCMD process. </LI> <LI> Suspended solids had more significant influence on the flux than dissolved solids. </LI> <LI> Flux with suspended solids concentration was suggested as J = B { P f 0 ( 1 − a <SUB> C ss </SUB> ) − P p 0 } . </LI> <LI> Modeling provided more understandings on the membrane distillation process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

고차원에서 높이차 제한이 있는 고체상고체 평형모델

박대호,김진민 한국물리학회 2019 새물리 Vol.69 No.8

높이차 제한이 있는 고체상고체 평형모델을 3차원과 4차원에서 시뮬레이션 하였다. 고체상고체 평형모델은 서로 인접한 자리의 표면 높이차에 제한이 있고 증착 확률과 증발 확률이 같은 경우이다. 3 차원에서 표면 높이의 분산 W2(t)는 log(t)로 시간에 따라 자라고 W2(L; t) log[L2af(t/Lz)]의 축척을만족한다. 여기서 z = 2:03을 사용하였다. 4차원에서는 포화된 표면 거칠기 W2(L)이 크기 L에 거의관계 없이 일정하다. 이경우 W2(L; t) = Wint2 L2g(t/Lz)의 축척을 만족한다. 여기서 = 0:51 와 z = 2:01의 값을 얻었다. 이를 통해 높이차 제한이 있는 고체상 고체 평형 모델은 높은 차원에서도Edwards-Wilkinson 보편성군에 속함을 보였다. We study the equilibrium restricted solid-on-solid model in d = 3 and d = 4 dimensions. The equilibrium model is a special case of the restricted solid-on-solid model with the same evaporation and deposition probability. The dispersion W2(t) of the surface height increases as log t with time t and satisfies the scaling form W2(L; t) log[L2af(t/Lz)] with z = 2:03 in d = 3. The saturated W2 sat(L) is almost independent of the system size L and follows W2(L; t) = Wint2L2g(t/Lz) with = 0:51 and z = 2:01 in d = 4. Our numerical results support the statement that the equilibrium restricted solid-on-solid model belongs to the Edwards-Wilkinson universality class even in higher dimensions.

Discrete Phase Modeling Study for Particle Motion in Storm Water Retention

호정석,김원일 대한토목학회 2012 KSCE Journal of Civil Engineering Vol.16 No.6

This study compares three different types of multiple phase models to determine the most appropriate one for predicting the behavior of various types of storm water solids in a rectangular retention chamber. Two Lagrangian frame of coupled and uncoupled particle tracking models based on the interaction between the discrete phase and the continuous phase were tested. The third model was a sediment transport model using the Eulerian frame. This study tested five different storm water solids classified by particle size and settling characteristics. Particle retention efficiency and computational time were considered in determining the most appropriate multiphase model. For the gross solids, the Lagrangian coupled model provided the best agreement with the physical model measurements. The Eulerian frame model matched retention efficiency well for the high density coarse and finer solids. Although the Eulerian frame shows reliable retention prediction for most of the solid types, the Lagrangian coupled model can be an effective alternative requiring significantly reduced computational time.

이수의 유동 특성 분석을 위한 고체-액체 2상 유동의 전산유체역학적 유효성 검토

최용석,박재현,배재환,이봉희,김정환 해양환경안전학회 2018 해양환경안전학회지 Vol.24 No.5

본 연구에서는 이수의 유동 특성을 분석하기 위한 기초 연구로서 상용 코드인 ANSYS CFX 14.5를 이용하여 고체-액체 2상 유동 에 대한 수치해석적 연구를 수행하였다. 고체-액체 2상 유동 현상을 모사하기 위해서 균질류 모델과 분리류 모델을 사용하였다. 분리류 모델에서는 Gidaspow의 항력모델을 적용하였으며, 고체 입자에 운동 이론 모델을 적용하였다. 기존의 실험 결과를 기반으로 본 연구에서 사용한 수치해석 모델의 유효성을 검토하였으며, 수치해석은 직경 54.9 mm, 길이 3 m의 수평관에서 체적 분율 0.1~0.5, 속도 1~5 m/s 범위에서 수행되었다. 그리고 압력강하와 고체 입자의 체적 분율 분포를 확인하였으며, 압력강하는 균질류 모델과 분리류 모델이 각각 MAE 17.04%, 8.98 % 이내에서 실험결과를 잘 예측하였다. 관의 하부에서 높은 체적 분율이 나타나며, 상부로 갈수록 체적 분율은 감소하였다. 그리고 속도가 증가할수록 높이 변화에 따른 체적 분율 분포의 변화는 감소하였으며, 수치해석 결과는 이러한 유동 특성을 잘 예측하였다. In this study, numerical analysis of solid-liquid two-phase flow was conducted as a preliminary step to analyze the flow characteristics of drilling fluid using the commercial CFD code, ANSYS CFX 14.5. The homogeneous model and separated flow model were used to simulate solid-liquid two-phase flow phenomena. In the separated flow model, Gidaspow's drag force model was applied with the kinetic theory model was applied for solid particles. The validity of the numerical model used in this study was verified based on the published experimental results. Numerical analysis was carried out for volume fractions of 0.1 to 0.5 and velocities of 1 to 5 m/s in a horizontal tube with a diameter of 54.9 mm and a length of 3 m. The Pressure drop and volume fraction distribution of solid particles were confirmed. The pressure drop was predicted using the homogeneous model and separated flow model within the MAE of 17.04 % and 8.98 %, respectively. A high volume fraction was observed in the lower part of the tube, and the volume fraction decreased toward the upper part. As velocity increased, variations in volume fraction distribution at varying heights were decreased, and the numerical results predicted these flow characteristics well.

Analysis of corrugated steel web beam bridges using spatial grid modelling

Dong Xu,Yingsheng Ni,Yu Zhao 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4

Up to now, Japan has more than 200 corrugated steel web composite beam bridges which are under construction and have been constructed, and China has more than 30 corrugated steel web composite beam bridges. The bridge type includes the simply supported beam, continuous beam, continuous rigid frame and cable stayed bridge etc. The section form has developed to the single box and multi-cell box girder from the original single box and single chamber. From the stress performance and cost saving, the span range of 50~150 m is the most competitive. At present, the design mostly adopts the computational analytical method combining the spatial bar system model, plane beam grillage model and solid model. However, the spatial bar system model is short of the refinement analysis on the space effect, such as the shear lag effect, effective distribution width problem, and eccentric load factor problem etc. Due to the similarity of the plane beam grillage method in the equivalence principle, it cannot accurately reflect the shearing stress distribution and local stress of the top and bottom plates of the box type composite beam. The solid model is very difficult to combine with the overall calculation. Moreover, the spatial grid model can achieve the refinement analysis, with the integrity of the analysis and the comprehensiveness of the stress checking calculation, and can make up the deficiency of the analytical method currently. Through the example verification of the solid model and spatial grid model, it can be seen that the calculation results for the stress and the displacement of two models are almost consistent, indicating the applicability and precision of the spatial grid model.