• Korean Journal of Agricultural Science
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• v.39 no.3
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• pp.407-412
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• 2012

Soil texture has an important influence on agriculture such as crop selection, movement of nutrient and water, soil electrical conductivity, and crop growth. Conventionally, soil texture has been determined in the laboratory using pipette and hydrometer methods requiring significant amount of time, labor, and cost. Recently, in-situ soil texture classification systems using optical diffuse reflectometry or mechanical resistance have been reported, especially for precision agriculture that needs more data than conventional agriculture. This paper is a part of overall research to develop an in-situ soil texture classification system using image processing. Issues investigated in this study were effects of sensor travel speed and light source and intensity on image quality. When travel speed of image sensor increased from 0 to 10 mm/s, travel distance and number of pixel were increased to 3.30 mm and 9.4, respectively. This travel distances were not negligible even at a speed of 2 mm/s (i.e., 0.66 mm and 1.4), and image degradation was significant. Tests for effects of illumination intensity showed that 7 to 11 Lux seemed a good condition minimizing shade and reflection. When soil water content increased, illumination intensity should be greater to compensate decrease in brightness. Results of the paper would be useful for construction, test, and application of the sensor.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.671-678
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• 2015

When evaluating the feasibility of construction projects of large-scaled transportation facilities such as roads or railways based solely on the result of the economic analysis, less development indicators are politically reflected on the investment decision-making because regions whose socio-economic indicators are poor may be disadvantaged or underserved for the projects. Existing less development indicators, however, does not consider the transportation connectivity which indicates how effective the transportation networks are established for the transport of people and goods. In this study, travel time contour maps, travel distance and travel time between regions, and a route curvature were utilized to define new indices which reflect transportation connectivity on the less development indicators. When the new indices are applied, the existing rankings of under-developedness were changed, which means that transportation connectivity could effect on the political decision. In this study, we also suggested the necessity of considering the transportation connectivity when evaluating less development indicators, developed measures of inter-regional linkages, and performed the whole procedures of combining existing and new indices to evaluate the less development indicators.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.800-813
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• 2021

With the advent of 5G communications, internet of vehicles technology has been widely used in vehicles. Then the dynamic spread of information between vehicles began to come into focus with more research. It is well known that the identification of nodes with great spread influence has always been a hot topic in the field of information spreading. Most of the existing work measures the propagation influence by degree centrality, betweenness centrality and closeness centrality. In this paper, we will identify influential vehicle nodes based on the mobility characteristics of vehicles to explore the information spreading between vehicles in VANETs. Different from the above methods, we mainly explore the influence of the radius of gyration and vehicle kilometers of travel on information spreading. We use a real vehicle trajectory data to simulate the information transmission process between vehicles based on the susceptible-infected-recovered SIR model. The experimental results show that the influence of information spreading does not enhance with increasing radius of gyration and vehicle kilometers of travel. The fact is that both the radius of gyration and the distance travelled have a significant influence on information spreading when they are close to the median. When the value of both is large or small, it has little influence on information spreading. In view of this results, we can use the radius of gyration and vehicle kilometers of travel to better facilitate the transmission of information between vehicles.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.3
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• pp.247-255
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• 2021

Individual passenger transfer information is not included in Seoul metropolitan subway Automatic Fare Collection (AFC) data. Currently, basic data such as travel time and distance are allocated based on the TagIn terminal ID data records of AFC data. As such, knowledge of the actual path taken by passengers is constrained by the fact that transfers are not applied, resulting in overestimation of the transport index. This research proposes a method by which a transit path that connects the TagIn and TagOut terminal IDs in AFC data is determined and applied to the transit index. The method embodies the concept that a passenger's line of travel also accounts for transfers, and can be applied to the transit index. The path selection model for the passenger calculates the line of transit based on travel time minimization, with in-vehicle time, transfer walking time, and vehicle intervals all incorporated into the travel time. Since the proposed method can take into account estimated passenger movement trajectories, transport-related data of each subway organization included in the trajectories can be accurately explained. The research results in a calculation of 1.47 times the values recorded, and this can be evaluated directly in its ability to better represent the transportation policy index.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1B
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• pp.47-55
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• 2011

This study suggests new synthetic unit hydrograph method considering hydrodynamic characteristic on the basin. The suggested method based on width function GIUH, and the procedure is summarized as follows; 1) Draw up a travel distance distribution map (width function) which is raster of length between from center of individual cells to the outlet by GIS. 2) Calculation of travel time distribution map (rescaled width function) by hydrodynamic parameters and travel distance distribution map. 3) Derivation of IUH and Duration UH from rescaled width function. 4) Comparison of shape of UH between suggested method and existing synthetic unit hydrograph methods. The target basins are selected Ipyeong and Tanbu subwatershed in the Bocheong Basin. The target basins are similar scale (watershed area), but different drainage structure (drainage density et al.). Therefore we anticipate that there are different hydrologic response functions because different hydrodynamic characteristics. As a result of derivation of UH, existing synthetic unit hydrograph methods are similar shape of UHs about Ipyeong and Tanbu watersheds, but the suggested method is different shape of ones. As a result of application to observed data, the peak discharge by suggested method is similar to existing synthetic unit hydrograph methods, but the peak time is well correspondence between those. Henceforth, if the suggested method combines with the rational velocity estimation method, it is useful method for synthetic of UH in ungauged watershed.

• Journal of Korean Society of Transportation
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• v.21 no.1
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• pp.91-102
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• 2003

There are two goals in this paper. The one is development of existing CA(Cellular Automata) model to explain more realistic deceleration process to stop. The other is the application of the updated CA model to forecasting simulation to predict short term link travel time that takes a key rule in finding the shortest path of route guidance system of ITS. Car following theory of CA models don't makes not response to leading vehicle's velocity but gap or distance between leading vehicles and following vehicles. So a following vehicle running at free flow speed must meet steeply sudden deceleration to avoid back collision within unrealistic braking distance. To tackle above unrealistic deceleration rule, “Slow-to-stop” rule is integrated into NaSch model. For application to interrupted traffic flow, this paper applies “Slow-to-stop” rule to both normal traffic light and random traffic light. And vehicle packet method is used to simulate a large-scale network on the desktop. Generally, time series data analysis methods such as neural network, ARIMA, and Kalman filtering are used for short term link travel time prediction that is crucial to find an optimal dynamic shortest path. But those methods have time-lag problems and are hard to capture traffic flow mechanism such as spill over and spill back etc. To address above problems. the CA model built in this study is used for forecasting simulation to predict short term link travel time in Kangnam district network And it's turned out that short term prediction simulation method generates novel results, taking a crack of time lag problems and considering interrupted traffic flow mechanism.

• Journal of Korean Society of Transportation
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• v.35 no.3
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• pp.234-246
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• 2017

The Seoul metropolitan government introduced the bus information systems, bus rapid transit to increase travel speed and punctuality but still suffer from insufficiency. This paper delivers a study verifying the external factors at near the bus stops. The dependent variable was set to the standard deviation of (1) travel time and (2) travel time to and from the bus stop in this study. The independent variables were set to (1) the number of routes, (2) traffic volume by bus type, (3) the number of bus bays, (4) the possibility of passing, (5) the distance to crosswalks and intersections, and (5) the presence of residential road. The results showed that the most significant factors included the link section speed, number of bus bay, distance to crosswalk, and the possibility of passing.

• Journal of the Korean Society for information Management
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• v.28 no.3
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• pp.163-178
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• 2011

Using the library users' data in Lake County Public Library Systems, Florida, US, this study discussed how geographic information systems can be applied in LIS fields. These data were analyzed with such GIS functions as geocoding, Thiessen polygon, density, buffer, and distance measurement. Results indicate that findings from a study of these functions allowed for, not only a better understanding of the geographic locations of library users and user's library activity patterns, but also for the ability to identify library market areas for future library service planning. Additionally, results from a study of the Thiesen polygon and buffer functions indicated the distance impact on library use. Regarding the travel distance of library users, the measurement of distance using road networks was suggested.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.567-571
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• 1992

A guidance loop of the missile system which uses a command to line of sight(CLOS) guidance law is designed based on LQG theory. In the environment of the severe tracking system noise, the system requires small aerodynamic control fin travel and small miss distance simultaneously. Results from a sample airframe shows good performance against a randomly maneuvering target.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.1
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• pp.127-134
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• 1992

In this paper, we first examine the stochastic behavior associated with storage/retrieval process under COL policy, and give analytical results such as the limiting distributions of the number of items in the system and the expected travel distance. We also investigate the phenomenon of natural zoning, that is, the tendency of similar items to group themselves together, when two types of items with different turnover rates are stored and retrieved. Natural zoning refers to this grouping occurring under the seemingly unbiased policy COL. We show that zoning can occur naturally with batch arrivals to the storage system.