• 제어로봇시스템학회논문지
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• 제22권7호
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• pp.557-561
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• 2016

Recently, in the manufacturing process of flat panel displays, mass production methods of inline system has been emerged. In particular the next generation OLED display manufacturing process, horizontal inline evaporation process has been tried. It is important for the success of OLED inline evaporation process to develop a magnetic levitation transport system capable of transferring a carrier equipped with a mother glass with high accuracy without any physical contact along the rail under vacuum condition. In the case of existing wheel-based transfer system, it is not suitable for OLED evaporation process requiring high cleanliness. On the other hand, the magnetic levitation transport system has an advantage that it does not generate any dust and it is possible to achieve high-precision control because there are not non-linear factors such as friction force. In this paper, we introduce the high-precision magnetic levitation transport system, which is currently under development, for OLED evaporation process.

• 한국정밀공학회지
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• 제12권7호
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• pp.92-98
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• 1995

In the cluster tool, it is necessary to precisely control the vacuum pressure for the wafer transportation between transport module and cassette or process modules with the range of 1*10$^{-4}$ to 5*10$^{-5}$ torr. So we have designed the pressure control system for the transport module of the cluster tool and have evaluated its performance. Digital PID is utilized with the weighted sum of both three previous errors and one current error. The feedback signal is put into the nitrogen mass flow controller using the transport module controller. This pressure control system can prevent the transport module from the particle generation and backstreaming of hazardous process gases of the process chamber.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.1739-1744
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• 2010

하천에서 유사이송 및 하상변동을 예측하는 여러 방법들 중 수치모형을 이용하는 방법이 현재 가장 많이 이용되고 있으며 특히 단일 유사량 산정 공식과 유사이송 형태를 현장자료와의 검증과정 없이 대부분 그대로 적용하고 있는 실정이다. 수치모형을 이용한 특정 대상하천의 정확한 하상변동 예측을 위해서는 유사량 산정 공식 및 유사 이송 형태에 따른 하상변동 민감도 분석 및 모형 검증과 검정 작업이 반드시 필요하며 이러한 과정을 통해 대상하천에 대한 최적의 유사량 산정 공식과 유사 이송 형태를 선정해야 할 것이다. 본 연구는 실제하천을 대상으로 여러 유사량 산정 공식과 유사 이송 형태를 다르게 적용이 가능한 CCHE2D 모형을 이용하여 하상변동 수치모의를 수행하였다. 유량 크기별 모의조건을 적용하여 하상변동 민감도를 분석을 통해 대상하천에서 적합한 유사량 공식과 이송 형태를 선정하고 실제수문사상의 유량 및 수위 조건을 적용하여 모의를 수행한 결과와 대상 하천에서 측량한 단면과 비교하여 검정을 실시하였다.

• Fisheries and Aquatic Sciences
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• 제1권1호
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• pp.48-62
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• 1998

Seasonal volume transport on the Texas-Louisiana continental shelf is investigated in terms of objectively fitted transport streamfunction fields based on the current meter data of the Texas­Louisiana Shelf Circulation and Transport Processes Study. Adopted here for the objective mapping is a method employing a two-dimensional truncated Fourier representation of the streamfunction over a domain, with the amplitudes determined by least square fit of the observation. The fitting was done with depth-averaged flow rather than depth-integrated flow to reduce the root-mean-square error. The fitting process filters out $11\%$ of the kinetic energy in the monthly mean transport fields. The shelf-wide pattern of streamfunction fields is similar to that of near-surface velocity fields over the region. The nearshore transport, about 0.1 to 0.3 Sv $(1 Sv= 10^6\;m^3/sec)$, is well correlated with the seasonal signal of along-shelf wind stress. The spring transport is weak compared to other seasons in the inner shelf region. The transport along the shelf break is large and variable. In the southwestern shelf break, transport amounts up to 4.7 Sv, which is associated with the activities of the encroaching of energetic anticyclonic eddies originated in Loop Current of the eastern Gulf of Mexico. The first empirical orthogonal function (EOF) of streamfunction variability contains $67.3\%$ of the variance and shows a simple, shelf-wide, along-shelf pattern of transport. The amplitude evolution of the first EOF is highly correlated (correlation coefficient: 0.88) with the evolution of the along-shelf wind stress. This provides strong evidence that the large portion of seasonal variation of the shelf transport is wind-forced. The second EOF contains $23.7\%$ of the variance and shows eddy activities at the southwestern shelf break. The correlation coefficient between the amplitudes of the second EOF and wind stress is 0.42. We assume that this mode is coupled a periodic inner shelf process with a non-periodic eddy process on the shelf break. The third EOF (accounting for $7.2\% of the variance) shows several cell structures near the shelf break associated with the variability of the Loop Current Eddies. The amplitude time series of the third EOF show little correlation with the along-shelf wind.

• 한국시스템다이내믹스연구
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• 제11권1호
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• pp.59-83
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• 2010

The Korean Government decided to reduce 30% of carbon emissions as of 2020, tightening regulations to reduce greenhouse gas in the international society. Therefore it will burden Korean logistics industry that overland trucking freight covers 70~80% of all, to lower emissions. As known, rail and coast(feeder) transport systems can be substituted for road transport but there are many problems to solve in Korean multimodal (intermodal) transport system such as time, cost, etc. Because of this, multimodal transport system should be improved systematically. For the reason, it aims to study a conceptual model with Thinking Process of TOC(theory of constraints) and System Dynamics to help improve the existing multimodal transport system for green logistics.

• Korean Journal of Geomatics
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• 제4권2호
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• pp.53-57
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• 2004

Due to the traffic congestion and public-oriented transportation policies of Seoul, public transportation is receiving attention and being used increasingly. However, current transport routes configuration is showing unbalanced accessibility throughout the city area creating differences in time, expenses and metal burden of users who travel the same distances. One of the reasons is that transport route planning has been partially empirical and non-quantitative tasks due to lack of relevant methods for assessing the complexity of the transport routes. This paper presents a method to compute the connectivity of public transport system based on the topological structure of the network of transport routes. The main methodological issue starts from the fact that the more transfers take place, the deeper the connectivity becomes making that area evaluated as less advantageous as for public transport accessibility. By computing the connectivity of each bus or subway station with all others in a city, we can quantify the differences in the serviceability of city areas based on the public transportation. This paper is based on the topological interpretation of the routes network and suggests an algorithm that can automate the computation process. The process is illustrated using a simple artificial network data built in a GIS.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 3차
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• pp.140-145
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• 2010

Consolidation in cohesive soils mainly focuses on compressibility of soils, but it affects solute transport in some cases. The consolidation process takes on particular significance for fine grained soils at high water content, such as dredged sediments, but has also been shown to be important for compacted clay liners during waste filling operation. Numerical investigation using CST1 and CST2 was reviewed on consolidation-induced solute transport in this paper, especially with the development of CST2 model, verification by comparing experimental results with numerical simulations, and cases studies regarding transport in a confined disposal facility (CDF) and during in-situ capping. The importance of the consolidation process on solute transport is accessed based on simulated concentration or mass breakthrough curves. Results indicate that neglecting transient consolidation effects may lead to significant errors in transport analyses, especially with soft contaminated cohesive soils undergoing large volume change.

• 대기
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• 제14권3호
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• pp.29-40
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• 2004

It is well known that convections and fronts are the most effective weather systems for the vertical transport of pollutants. I used a two dimensional front model in order to investigate the mechanism of the vertical transport of atmospheric pollutants between planetary boundary layer(PBL) and free atmosphere by fronts. The main dynamic processes which contribute the vertical transport of pollutants are advection and diffusion. The transported amount of pollutant from the boundary layer to the free atmosphere increases dramatically during the developing stage of the front. 46% of pollutants are transported vertically within 12 hour and 54% are transported within 24 hour. In the meantime, compared to the total amount of pollutants transported by both advection and diffusion, about 25% (30%) less pollutants are transported when only advection (diffusion) process in included in the model. The most important mechanism for the vertical transport is vertical advection, while the vertical diffusion process plays an important role in the redistribution of pollutants in the PBL.

• Computers and Concrete
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• 제31권6호
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• pp.485-499
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• 2023

Both damage and unsaturated conditions accelerate the transport of erosive media inside concrete. However, their combined effects have not been fully investigated. A multiscale mortar model using representative volume elements is developed, capturing the number and distribution in each phase. Afterwards, mortar damage microstructure evolution is simulated in the tensile process. Finally, the unsaturated mortar transport is predicted and analysed. The results indicate that damage significantly affects the diffusion process in the early stage, while the transport performance is weakened due to the obstruction of the nontransport phase in the later stage. The higher the saturation and the more connected pores, the faster the diffusion rate of chloride ions. Chloride ions spread around the cracks in a tree-like manner along. The model can very well predict the chloride ion transport performance of unsaturated and damaged mortar.

• 전기학회논문지
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• 제67권1호
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• pp.87-95
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• 2018

The high-precision magnetic levitation transport system is a transport device applying the principle of magnetic levitation. So it is preferable for manufactory process of semiconductor and display industries. In this system, the gap sensors are arranged discontinuously and turned on or off when the tray moves in the running direction. Therefore, precise gap data is important for precise control of the carrier. However, a slight error occurs in the process of installing the gap sensor. So, in this paper, we introduce the high-precision magnetic levitation transport system for OLED evaporation process. Also, we propose a strategy for stable flight control and an offset algorithm for tracking installation errors transport system. The performances of the proposed algorithm are validated through simulation.