• Journal of Korean Society of Transportation
• /
• v.34 no.6
• /
• pp.570-579
• /
• 2016

This study proposes a concept of Stepwise Transfer Coefficient(STC) which implies greater transfer cost with increasing the number of transfers. Thus, the public transport information system provides the choice sets of travel routes by the consideration of not only transportation time but also the optimum number of transfers. However, path choice problems that involve STC are found to include non additive cost, which requires additional route enumeration works. Discussions on route enumeration in actual transportation networks is very complicated, thereby warranting a theoretical examination of route search considering STC. From these points of view, this study results in a probability based transit trip assignment model including STC. This research also uses incoming link based entire route deletion method. The entire route deletion method proposed herein simplifies construction of an aggregation of possible routes by theoretically supporting the process of enumeration of the different routes from origin to destination. Conclusively, the STC reflected route based logit model is proposed as a public transportation transit trip assignment model.

• Journal of Korean Society of Transportation
• /
• v.24 no.5 s.91
• /
• pp.77-88
• /
• 2006

The purpose of this study is to Propose the time dependent K-least time path algorithm applicable to a real-time based operation strategy in multi-modal transportation network. For this purpose, we developed the extended method based on entire path deletion method which was used in the static K-least time path algorithm. This method was applied to time dependent K-least time path algorithm to find k least time paths in order based on both time dependant mode-link travel time and transfer cost In particular, this algorithm find the optimal solution, easily describing transfer behavior, such as walking and waiting for transfer by applying a link-based time dependent label. Finally, we examined the verification and application of the Proposed algorithm through case study.

• Journal of Korean Society of Water and Wastewater
• /
• v.22 no.2
• /
• pp.239-243
• /
• 2008

The fluctuation of inlet flow to a water treatment plant makes a serious problem that it can change the outlet flow-rate from each process abruptly, and ultimately occur the detachment of the attached particles inside each unit process. Also, since it takes very short time for the surface wave occurred from the fluctuation of inlet flow to reach the latter processes, it is impossible for operators to cope with that stably. Therefore this study was conducted to suggest the methodology for accurately predicting the travel time of surface wave occurred from the fluctuation of inlet flow to reach the latter process. Through the experiment, which was carried out for the full-scale water treatment plants(capacity : 2,000m3/d), it could be confirmed that the flow rate fluctuation from equalization tank produce the surface wave. And the wave transfer velocity is a function of the hydraulic radius and the length of each open type tanks which are comprised in the latter processes.

• Nuclear Engineering and Technology
• /
• v.53 no.10
• /
• pp.3421-3430
• /
• 2021

Spherical NaI(Tl) detectors are used in gamma-ray spectrometry, where the gamma emissions come from the nuclei with energies in the range from a few keV up to 10 MeV. A spherical detector is aimed to give a good response to photons, which depends on their direction of travel concerning the detector center. Some distortions in the response of a gamma-ray detector with a different geometry can occur because of the non-uniform position of the source from the detector surface. The present work describes the calibration of a NaI(Tl) spherical detector using both an experimental technique and a numerical simulation method (NSM). The NSM is based on an efficiency transfer method (ETM, calculating the effective solid angle, the total efficiency, and the full-energy peak efficiency). Besides, there is a high probability for a source-to-detector distance less than 15 cm to have pulse coincidence summing (CS), which may occur when two successive photons of different energies from the same source are detected within a very short response time. Therefore, γ-γ ray CS factors are calculated numerically for a ¹⁵²Eu radioactive cylindrical source. The CS factors obtained are applied to correct the measured efficiency values for the radioactive volumetric source at different energies. The results show a good agreement between the NSM and the experimental values (after correction with the CS factors).

• International Journal of Precision Engineering and Manufacturing
• /
• v.7 no.1
• /
• pp.35-41
• /
• 2006

In this paper, we develop anti-sway control in proposed techniques for an ATC system. The developed algorithm is to build the optimal path of container motion and to calculate an anti-collision path for collision avoidance in its movement to the finial coordinate. Moreover, in order to show the effectiveness in this research, we compared NNP PID controller to be tuning parameters of controller using NN with 2-DOF PID controller. The experimental results jar an ATC simulator show that the proposed control scheme guarantees performances, trolley position, sway angle, and settling time in NNP PID controller than other controller. As a result, the application of NNP PID controller is analyzed to have robustness about disturbance which is wind of fixed pattern in the yard.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.607-613
• /
• 2011

This paper reviews search methods of multiple reasonable paths to implement multimodal public transportation network of Seoul. Such a large scale multimodal public transportation network as Seoul, the computation time of path finding algorithm is a key and the result of path should reflect route choice behavior of public transportation passengers. Search method of alternative path is divided by removing path method and deviation path method. It analyzes previous researches based on the complexity of algorithm for large-scale network. Applying path finding algorithm in public transportation network, transfer and loop constraints must be included to be able to reflect real behavior. It constructs the generalized cost function based on the smart card data to reflect travel behavior of public transportation. To validate the availability of algorithm, experiments conducted with Seoul metropolitan public multimodal transportation network consisted with 22,109 nodes and 215,859 links by using the deviation path method, suitable for large-scale network.

• Proceedings of the KSR Conference
• /
• 2005.05a
• /
• pp.1084-1092
• /
• 2005

Various urban transport policies have an effect on urban transit riderships. This study reports variations of metropolitan subway travel patterns affected by an enormous change in bus routes and transfer discount policy between subway and bus mode conducted by Seoul city in July 1st of 2004. In an effort to see the difference between the before and the after policies, two datasets are prepared. Firstly, on a daily bassis, an origin-destination trip table of May of 2004 is used. Secondly, on a daily bassis, an origin-destination trip table of August-September of 2004 is used as a counter measure. Even if seasonal variation was not considered. there were increasing riderships of about 0.25 million on a daily basis. Subway line 2 and 7 have an important role in changes. The effects or system changes, however. largely varied on location and subway line numbers.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.10
• /
• pp.2607-2616
• /
• 1995

The influences of number of spark plug on ignitability, combustion characteristics and combustion promotion effect were examined to establish the design conception of spark ignition system for lean burn. Ignitability was increased remarkably by increasing of number of spark plug at combustion wall. Combustion duration was shortened and maximum combustion pressure was increased in accordance with increasing of spark plug number. Rate of overall combustion promotion considered of combustion duration and combustion pressure was 28% in two point ignition and 40% in four point ignition. It was verified that heat release, heat loss and combustion duration were affected by flame area, heat transfer area and maximum flame travel distance respectively.

• Journal of the Korean Society of Industry Convergence
• /
• v.12 no.1
• /
• pp.19-25
• /
• 2009

We suggest and evaluate a dynamic scheduling rule of machines and material handling systems for on-line operation in job shop type Flexible Manufacturing System. Alternating status should be able to take operation scheduling procedures and without delay in dynamic industrial environments effectively. The interaction(SPT-NS, SPT-QSNS, SPT-NUJ, EDD-NS, EDD-QSNS, EDD-NUJ, CR-NS, CR-QSNS, CR-NUJ) between machine operation scheduling and AGV dispatching rule were also studied in this research. The performance evaluation which was obtained from DSS compares the performance of Flow time, and Empty to loaded travel ratio. It is Compared with the best rules & two system.

• Journal of the Korean Society of Safety
• /
• v.5 no.3
• /
• pp.33-38
• /
• 1990

In this study, the transient temperature distribution of welded zone was analyzed by Finite Element Method for the optimal design of weldment. This study was carried out for the steel plate 8mm thick, 100mm wide, 100mm long that butt weld. The weld was made with a heat input of 2,250 joule/cm(arc current ： 180 amperes ； arc voltage ：25 volts ； and arc travel steed ： 0.28 cm/sec). In the analysis of temperature, cooling in the welded zone by the conduction between materal was almost completed at 600 sec when a unique temperature field was formed. after this, the material was gradually cooled by the heat transfer to the circumference. In the early phase the temperature in base metal zone is little changed. but after the rise in temperature the whole area is cooled gradually.