• KIPS Transactions on Computer and Communication Systems
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• v.5 no.12
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• pp.447-454
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• 2016

The research on multipath routing has been studied to solve the problem of frequent path breakages due to node and link failures and to enhance data delivery reliability in wireless sensor networks. In the multipath routing, mobile sinks such as soldiers in battle fields and rescuers in disaster areas bring about new challenge for handling their mobility. The sink mobility requests new multipath construction from sources to mobile sinks according to their movement path. Since mobile sinks have continuous mobility, the existing multipath can be exploited to efficiently reconstruct to new positions of mobile sinks. However, the previous protocols do not address this issue. Thus, we proposed an efficient multipath reconstruction protocol called LGMR for mobile sinks in wireless sensor networks. The LGMR address three multipath reconstruction methods based on movement types of mobile sinks: a single hop movement-based local multipath reconstruction, a multiple hop movement-based local multipath reconstruction, and a multiple hop movement-based global multipath reconstruction. Simulation results showed that the LGMR has better performance than the previous protocol in terms of energy consumption and data delivery delay.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.47-51
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• 2014

This paper is to analyze and study the fire examples in respect of intake and exhaust, alternator tuning and inflow of inflammables on exhaust part in a car. In the first example, the driver diverted the intake and exhaust system for tuning of a car. Stopping a car to rest for moment, the flammable styrofoam scrap go into exhaust pipe that installed with exhaust manifold newly. It certified the fact that catched fire gradually, furthermore enlarged the fire by leaking fuel. In the second example, the driver enlarged the generator performance to divert the audio system in side room., it knew the fact that the electric wiring connected with generator gave the cause of outbreak a fire by overheating. In the third example, the serviceman replaced the engine oil using funnel-shaped, he put the a bottle of plastic pat onto engine cover carelessly. Consequentially, it found the fire occurrence in the engine room. Therefore, the driver never divert the intake and exhaust and generator construction of a car abnormally. Also, repairing and inspecting a car, the serviceman have a care to not occur the fire by inflammables.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.101-110
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• 2010

In this paper, it has been studied about the CRCO to maintain or rehabilitate the aged JCP. The CRCO and JCO was constructed at useless section of Seo-Hae-Ahn express highway in South Korea. The performance evaluation was conducted. Especially, it was focused on the roll of longitudinal reinforced steels inserted into the CRCO. On crack survey results from field construction section, the reflection cracks at joint of the existing pavement occurred in CRCO. However, due to the constraints of longitudinal reinforced steels, crack width was small. Total crack length and quantity in the CRCO more than that in the JCO. And crack spacing in the CRCO was narrower than it in the CRCP. Through the bonding strength test results, if the cold milling and cleaning as well as surface treatment is applied, there will be no debonding problem at interlayer in the early age. From analysis of the horizontal behavior at the joint, the longitudinal reinforced steels constrained crack width which became wider than initial state over time. Also, that steel in the CRCO reduced the horizontal movement due to temperature variation(4 times than that in the JCO). But, if interface is debonded, the roll decreased. Vertical VWG data showed that CRCO did not occur debonding problem at steel location, but there was some problem in JCO. It was confirmed by field coring. The tensile strain appeared in the CRCO, But the compressive strain occurred in the JCO in early age. Through the FWD test result, deflection in the CRCO was less than that in the JCO. And K value in the CRCO was greater than it in the JCO.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.133-142
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• 2009

This research is performed to estimate quality of trial pavement for construction and analyze effect of fatigue life by using the pay factor. Specially, asphalt content which is difficult to control the pavement quality, is selected by pay adjustment standard factors and pay factor is calculated by asphalt content. This research is also analyzed to present relation of fatigue life according to asphalt content, to evaluate quality of the road pavement by calculating pay factor of sampling trial field mixture 2 times. This research confirms that it is different quality of road pavement according to pay factor changes. To analyze the fatigue life of pavement by using asphalt mixture for trial field. As a result, it is conformed that high pay factor could be high fatigue life of trial field. This means that pay factor using probability theory reflects road pavement fatigue life. Also, this study is included that beam fatigue test manufacturing specimen such as mixing type of plant which purvey asphalt mixture to trial field, compared with fatigue life of trial field. As a result, the fatigue life of specimen that is manufactured by mix type is higher than trial field specimen. This means that performance of road pavement can be reduced by gradation or other effects. Therefore, to exactly evaluate the quality of road pavement, pay factor should be calculated appling various pay adjustment standard factors such as gradation, air-void in U.S. states which is adopted pay adjustment.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.85-95
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• 2009

Congestion on expressways is increasing in spite of continuous road construction. In enlargement of expressway capacity to lessen congestion, a long period is needed and in the case of traffic congestion, it would be impossible to avoid long periods of traffic congestion. So, it is necessary to cope with traffic congestion through continuous traffic condition monitoring, analysis of the causes of congestion and the development of alternatives before traffic conditions worsen. A congestion index that can express traffic operating conditions measurably is needed to monitor those conditions. Thus, in this research, a new congestion index, the Traffic Condition Index (TCI), is developed. TCI is able to evaluate roads that have different grades (or design speeds) and to judge traffic condition as good, fair and poor (congested). In addition, TCI has merits in that it can strengthen the function of existing Freeway Traffic Management Systems (FTMS) and can be applied to congestion management easily: TCI calculates congestion intensity and severity using data obtained from existing FTMS. In order to validate TCI, it was applied to the Kyungbu Expressway and the Seohaean Expressway. As a result, TCI shows a good performance in the aspect of applicability and ability of presentation of traffic conditions compared with travel speed and Travel Time Index (TTI).

• Journal of Wetlands Research
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• v.15 no.3
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• pp.407-412
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• 2013

The aim of this study was to develop a tree box filter system, an example of Low Impact Development technology, for treating stormwater runoff from road. Monitoring of storm events was performed between June 2011 and November 2012 to evaluate the system performance during wet day. Based on the results, all runoff volume generated by rainfall less than 2 mm was stored in the system. The minimum volume reduction of 20% was observed in the system for rainfall greater than 20 mm. The greatest removal efficiency was exhibited by the system for total heavy metals ranging from 70 to 73% while satisfactory removal efficiency was exhibited by the system for particulate matters, organic matters and nutrients ranging from 60 to 68%. The system showed greater pollutant removal efficiency of 67 to 83% for rainfall less than 10 mm compared to rainfall greater than 10 mm which has 39 to 75% pollutant removal efficiency. The system exhibited less pollutant reduction for rainfall greater than 10 mm due to the decreased retention capacity of the system for increased rainfall. Overall, the system has proved to be an option for stormwater management that can be recommended for on-site application. Similar system may be designed based on several factors such as rainfall depth, facility size and pollutant removal efficiency.

• Journal of Korea Water Resources Association
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• v.40 no.1 s.174
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• pp.39-50
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• 2007

This paper presents applications of the log-linear ROCOF(rate-of-occurrence-of-failure) and the Weibull ROCOF to model the failure rate of individual cast iron pipes in a water distribution system and provides a method of estimating the economically optimal replacement time of the pipes using the 'modified time-scale'. The performance of the two ROCOFs is examined using the maximized log-likelihood estimates of the ROCOFs for the two types of failure data: 'failure-time data' and 'failure-number data'. The optimal replacement time equations for the two models are developed by applying the 'modified time-scale' to ensure the numerical convergence of the estimated values of the model parameters. The methodology is applied to the case study water distribution cast iron pipes and it is found that the log-linear ROCOF has better modeling capability than the Weibull ROCOF when the 'failure-time data' is used. Furthermore, the 'failure-time data' is determined to be more appropriate for both ROCOFs compared to the 'failure-number data' in terms of the ROCOF modeling performances for the water mains under study, implying that recording each failure time results in better modeling of the failure rate than recording failure numbers in some time intervals.

• Tunnel and Underground Space
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• v.20 no.2
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• pp.82-91
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• 2010

Grouting technology is one of the ground improvement methods used in water controlling and reinforcement of rock mass in underground structure construction. It is necessarily required to find out the characteristics of grout flow through discontinuities in a rock mass for an adequate grout design and performance assessment. Laminar flow is not always applicable in simulating a grout flow in a rock mass, since the rock joints usually have apertures at a micro-scale and the flow through these joints is affected by the joint roughness and the velocity profile of the flow changes partially near the roughness. Thus, the influence of joint roughness and aperture on the grout flow in rough rock joint was numerically investigated in this study. The commercial computational fluid dynamics code, FLUENT, was applied for this purpose. The computed results by embedded Herschel-Bulkley model and VOF (volume of fluid) model, which are applicable to simulate grout flow in a narrow rock joint that is filled with air and water, were well compared with that of analytical results and previously published laboratory test for the verification. The injection pressure required to keep constant injection rate of grout was calculated in a variety of Joint Roughness Coefficient (JRC) and aperture conditions, and the effect of joint roughness and aperture on grout flow were quantified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2402-2408
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• 2009

This study conducted a static tensile test in order to prevent the lowering of load carrying capacity caused by critical sections made by over bolt holes in the base plate and the cover plate of steel member joints using high-tension bolts. The change of the load carrying capacity of joints was examined by comparison of the maximum load on joint fracture obtained from the tensile test with critical section rate and design strength. According to the results, the rate of decrease in strength was higher when the critical section rate was high, and in particular, decrease in strength was affected much more by critical sections in the base plate than by those in the cover plate. In high-tension bolt joints using over bolt holes for the base plate and the cover plate, load carrying performance was somewhat lower than that in joints using standard bolt holes, but the maximum tensile strength on facture was over 15% higher than design fracture strength. According to the results of this study, the use of over bolt holes in high-tension bolt joints had an insignificant effect on the lowering of load carrying capacity, so the allowance of over bolt holes in the joints of steel members is expected to enhance to the economy and efficiency of the works.

• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.273-279
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• 2020

In the Korea's SBAS(KASS), reference site is an important infrastructure facility for the collecting and monitoring GPS/GEO signals. The SBAS reference station has an clear requirements than other regular monitoring stations. It requires constant maintenance during the system operation. The development for KRS site should be prepared for site survey, site construction, antenna geodetic survey, equipment installation and operation. Site survey is initially performed as an important step to predict site availability and system performance. The operation center must provide the reference site, equipment room, and appurtenant to satisfy the site requirements. The position of antennas is very important information, and accuracy must be secured through the geodetic survey. Measurement collected at the from precise antenna are provided to the KASS processing station. The position of antenna should be maintained through continuous position checks and updates during the operation. When the development of the KRS site is completed, it performs tasks for installing and operating the KRS equipment. In this paper, we presented the procedures and some results for the development of the 7 KRS sites.