• Proceedings of the KOR-KST Conference
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• 1995.05b
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• pp.252-272
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• 1995

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.466-472
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• 1988

Pneumatic transportation systems are operated most economically, if the transportation velocity is somewhat greater than the limit velocity. Therefore it is very important to find out this limit velocity. That is well known for coarse and fine particles, but not yet for long ribbon type material. In this study a formula for the mass ratio of transported material to air in limit load point is derived for ribbon type material from the pneumatic transportation theory and the model theory. A relationship for estimating the limit velocity is also found out through experiments. The possibility of the generalization of this formula, which is obtained from a given pneumatic transportation system, should be estimated through further systematic studies.

• Asian Journal of Atmospheric Environment
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• v.10 no.1
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• pp.51-56
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• 2016

Particulate matter (PM) in the atmosphere has wide-ranging health, environmental, and climate effects, many of which are attributed to fine-mode secondary organic aerosols. PM concentrations are significantly enhanced by primary particle emissions from traffic sources. Recently, in order to reduce $CO_2$ and increase fuel economy, gasoline direct injected (GDI) engine technology is increasingly used in vehicle manufactures. The popularization of GDI technique has resulted in increasing of concerns on environmental protection. In order to better understand variations in chemical composition of particulate matter from emissions of GDI vehicle versus a port fuel injected (PFI) vehicle, a high time resolution chemical composition of PM emissions from GDI and PFI vehicles was measured at facility of Transport Pollution Research Center (TPRC), National Institute of Environmental Research (NIER), Korea. Continuous measurements of inorganic and organic species in PM were conducted using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The HR-ToF-AMS provides insight into non-refractory PM composition, including concentrations of nitrate, sulfate, hydrocarbon-like and oxygenated organic aerosol, and organic mass with 20 sec time resolution. Many cases of PM emissions during the study were dominated by organic and nitrate aerosol. An overview of observed PM characteristics will be provided along with an analysis of comparison of GDI vehicle versus PFI vehicle in PM emission rates and oxidation states.

• Korean System Dynamics Review
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• v.10 no.3
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• pp.5-23
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• 2009

Transportation systems around the world are difficult to maintain sustainability that, in a broad sense, is the capacity to endure. By connecting Entropy theory and systems thinking, we find the current problems and seek alternative plans. Distortions of the current transportation system to improve individual's ease and increasing traffic congestion, impose us the heavy energy consumption and will make increase whole entropy. UNEP reports are presented following three reasons that undermine the sustainabillity. The first one is that the prevalent traffic system highlight benefits of accessibility than benefits of mobility, the second, deteriorate excessive energy consumption, and the last reason is that personal vehicles has inhibited the use of public transportation. Alternative ideas to enhance the sustainable transportation system are these; (1) changeover from 'Ease of movement' to 'space efficiency', (2) evolving the smart traffic system instead of the construction or expansion of the road and (3) creating more comfortable the use of mass transportation. In addition, there are another ways that encouraging modal shift that increase traffic of goods, transport over railway lines and waterways, decongesting transport corridors and elevating technology to improve public transportation. The most importantly, we converse our cognitive process to be willing to enjoy uncomfortable and annoying life.

• Industrial Engineering and Management Systems
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• v.9 no.4
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• pp.294-302
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• 2010

There is a trend toward the world's manufacturing sites moving to East Asia. After manufacture, these products are transported to the advanced nations for their consumption demands. Among such advanced nations, the U.S.A. has the largest demand, and then Japan and European countries follow. It should be noted that the infrastructures of the Asian districts used for the production sites are rather limited, and the volume of products transported from these districts of Asia to the U.S.A is becoming tremendously large. This situation is causing very serious traffic problems. New products are required to be transported swiftly by air. Once the consumption and market demands are stable however, the products should be sent rather slowly, but in larger amounts. However, the airports of China are quite restricted in capacity, while the transportation volume is becoming large. As a result, transportation cost and the time required for transportation are increasing. Now, a third method is appearing. This is the so-called Sea and Air transportation. The cost and time in transit of this mode take mean positions between Air and Ocean services. At present there exists no well-thought-out strategy for how to allocate these three methods of transportation. This paper is an attempt to theoretically describe this mechanism and to discover the optimal way to allocate the three modes. For this purpose, several mathematical properties of value and cost of the products are defined, and on this basis a simulation of the transportation is established.

• Journal of Institute of Convergence Technology
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• v.10 no.1
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• pp.41-45
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• 2020

This paper presents the effects of a virtual mass on the stability boundary of a virtual spring in the haptic system with first-order-hold. The virtual rigid body is modeled as a virtual spring and a virtual mass. When first-order-hold is applied, we analyze the stability boundary of the virtual spring through the simulation according to the virtual mass and the sampling time. As the virtual mass increases, the stability boundary of the virtual spring gradually increases and then decreases after reaching the maximum value. The results are compared with the stability boundary in the haptic system with zero-order-hold. When a virtual mass is small, the stability boundary of a virtual spring in the system with first-order-hold is larger than that in the system with zero-order-hold.

• Journal of Institute of Convergence Technology
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• v.6 no.2
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• pp.15-20
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• 2016

This paper presents the effects of a virtual mass on the stability boundary of a virtual spring in the haptic system. A haptic system consists of a haptic device, a sampler, a virtual rigid body and zero-order-hold. The virtual rigid body is modeled as a virtual spring and a virtual mass. According to the virtual mass and the sampling time, the stability boundary of the virtual spring is analyzed through the simulation. As the virtual mass increases, the value of the virtual spring to guarantee the stability gradually increases and then decreases after reaching the maximum value. These simulation results show that the addition of the virtual mass enables to expand the stability boundary of the virtual spring.

• Proceedings of the KSR Conference
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• 2008.06b
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• pp.27-41
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• 2008

Construction of metro transportation infra is a large-scale project requiring tremendous financial resources. This study suggests operation method to use for rapid transit line existing infra such as Gyeongbu line and spare line capacity following second phase KTX construction. Reviewing various constraints of metro rapid transit operation, we found that the conditions for metro rapid transit operation are already satisfied in Daegu area, just like the case of Gyeongbu line in Seoul Metro area. Also, the evaluation of the economic feasibility of metro rapid transit operation in Daegu area shows that B/C is about 2.4, which implies that there is sufficient economic feasibility. According to the result of sensitivity analysis, the project is economically feasible unless the passenger demand decreases 15% and construction costs increases more than 70%. B/C is evaluated large because the utilization of already exiting infra lowers the initial cost. As one of mass transportation system of large capacity, metro rapid transit can generate significant spillover effect: It will strengthen competitiveness of metro area by connecting cities within the area and by extending one-day life zone of the area, to say nothing of the benefit of improving traffic condition. The construction of metro rapid transit network is necessary for the mass transportation system of Yeongnam area as well as Daegu area, and it may work as a starting point for uniting Daegu and Gyeongbuk and strengthening regional competitiveness.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.697-702
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• 2006

A counterplan of slope failure has to investigate about various and engineering safety factors. Especially, it is important that large cut-slope must examine rational and economic solution. In this case study, cut-slope failure caused by inflow of rainwater into alternate layers. Hereafter it is suggested that large cut-slope should consider analysis the cause for a decline of safety factor and the engineering character of corestone ground mass.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.618-622
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• 2007

In the past decades, complain about ground vibration and noise induced by pile driving has been quickly increased. Because of that, auger The role of train has expanded as mass transportation according to the increase of train passenger. The train operation personnel are more emphasis on the safety of train operation due to the increase of train's role. The reason is that the train transports many people daily. So, if there is natural disaster, such as earthquake, flood, high temperature, and so on, it will become disaster. Therefore, this paper introduces and proposes wayside detection system, which can be helpful for the safety assurance of train operation.