• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.38-46
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• 1998

This study was to investigate the effects of carbon loadings, temperature and expansion ratio on the waterborne organic removal by the biologically active GAC fluidized bed on a laboratory scale. The raw water to be treated comes from midstream of Han river. BACFB(Biological Activated Carbon Fluidized Bed) process was very effective to remove the biodegradable fraction of dissolved organic matter. The more carbon weighed, the more DOC removed in a range from 16.7 to 133.3 g/l. DOC and UV$_{254}$ were removed more than 40% and 20% above 20$\circ$C respectively. Between 5$\circ$C and 10$\circ$C, DOC and UV$_{254}$ were eliminated about 30% and 15% respectively. In general, even if the temperature was higher, DOC removal was a little sensitive, probably influenced by GAC's residual adsorption capacity. UV$_{254}$ reduction was little fluctuated in accordance with water temperature. The gradual increase in expansion ratio from 10% to 75% didn't greatly affect on the removal of DOC and UV$_{254}$. The expansion ratio, therefore, is not a key factor over the critical expansion ratio.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.63-68
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• 2019

The dimensional quality of flexible foams is often difficult to be evaluated through general machine vision inspection methods due to the free deformation of the outer shape. For the evaluation of the dimensions of flexible foams, methods of estimating the size of the product through the expansion rate of the product surface are evaluated. Specimens with various dimensions and surface gratings are prepared, and the degree of surface expansion is measured through machine vision. The correlation, between the measured surface grid size and the actual size of test specimens, is analyzed. We further analyze the correlation between the size of test specimens and the position of the surface grid. This study provides a basis for estimating the actual dimensions of specimens by measuring the surface expansion of flexible foams.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.12
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• pp.1669-1680
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• 1998

A method is developed to include the effect of volume expansion in the description of the flame dynamics using G-equation. Line volume-source is used to represent the effect of the exothermic process of combustion with source strength assigned by the density difference between the burned and the unburned region. The present model provides good agreement with the experimental results. Including volume expansion, the flow field is adjusted to accommodate the increased volume flow rate which crossing the flame front and the result predicts the same behavior of measured velocity field qualitatively. The effect of increasing volume expansion does not change the initial growth rate of flame area but increase the residence time. Consequently this effect increases the maximum area of flame front. The flame propagation in varying flow field due to volume expansion provides a promising way to represent the wrinkled turbulent premixed flames in a numerically efficient manner.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.894-899
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• 1998

To absorb the deformation of live load, thermal gradient, shrinkage and creep in bridge structures and general structures, expansion joint has to be established. Especially expansion joint for high-speed railway bridge has to accomodate the static and dynamic forces and it not only has the durability of itself but also maintain the durability of structure by preventing the leakage of water. The actual used product of expansion joint for high-speed railway bridge is only ones made in France, Germany and Japan. In this study, the development process and test results of developed expansion joint are introduced which has the functional operation and durability enough to apply to high-speed railway bridges, roadway bridges and general structures. The tests consist of fatigue-durability test of 3 million times by high-speed rail load, leakage test and jack-up test for verifying the possibility of exchanging it. The performance of developed expansion joint satisfy the specification of Korea High Speed Rail Construction authority.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.540-549
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• 2018

This paper proposes the method of active distribution network expansion planning considering distributed generation integration and distribution network reconfiguration. The distribution network reconfiguration is taken as the expansion planning alternative with zero investment cost of the branches. During the process of the reconfiguration in expansion planning, all the branches are taken as the alternative branches. The objective is to minimize the total costs of the distribution network in the planning period. The expansion alternatives such as active management, new lines, new substations, substation expansion and Distributed Generation (DG) installation are considered. Distribution network reconfiguration is a complex mixed-integer nonlinear programming problem, with integration of DGs and active managements, the active distribution network expansion planning considering distribution network reconfiguration becomes much more complex. This paper converts the dual-level expansion model to Second-Order Cone Programming (SOCP) model, which can be solved with commercial solver GUROBI. The proposed model and method are tested on the modified IEEE 33-bus system and Portugal 54-bus system.

• Strategy21
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• s.41
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• pp.174-207
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• 2017

Human history shows diverse strategies for survival and prosperity. This study introduces the concept of the expansion of wealth as a key to explain choice and behavior of political entities. American scholar, -Bruce Bueno de Mesquita-, offers theoretical grounds for this concept in that the cores of selectorate theory is settled. The political entity consists of two groups, -the winning coalition that has power to replace leader and non-winning coalition that has not. Leaders implement policies serving for the welfare of winning coalition in return for their loyalty. Both internal problems caused by demographic changes and external ones of climate changes, epidemic disease, or invasion compel leader and winning coalition to adopt policies of expansion that they believe may lead to the acquisition of wealth needed to counter those problems. The process starts by occupying one spot where other entities reside and then connecting it to its own. The line between spots functions as a foothold to form a new line to other spots. By repeating this process, a space is created in which new laws and orders are instated. In the early stage of expansion, war is hardly avoidable. Once finished successfully, the political circumstance tilts to encourage economic activities in order to generate national revenues to strengthen political power of winning coalition. However, as scale of economic activities grows, so does political power of civic classes in production and trade. To gain financial support required to run the political entity, delegation of power or bestowing autonomy to non-winning coalition is inevitable. Thus, expansion is not the ultimate solution, only to prolong the political survival if succeed. Maritime power came to attractive option when overland expansion had become obstructed. It offered much greater advantages in terms of political risks and financial burdens in exploring new regions of precious commodities than overland expansion. Each political entity around world have been, for the first time in human history, connected by maritime means since 15th century. It is worthy of noting that land conditions propelled people out to sea. Political and economic situations created opportunities to exploit geographical position in pursuit of wealth. In the 21st century, we witness the operation of international winning coalition that presides over the rules of expansion. Competing for market is synonymous to the expansion in this era, the cause and aim of it has not been changed though. Energy and dollars are key factors of expansion since the end of the 2nd world war. No matter what the forms and conditions change, naval power is still the most relevant means for expansion as it retains unique characters of maneuver, flexibility, continuity, display and projection of power. The strategy for using naval power should be in line with two different approaches for expansion: Approaches to the international winning coalition by making contribution to world order, and approaches to the non-international winning coalition by enhancing military diplomatic activities. The former will serve our share of winning coalition while the latter will open chances to acquire further prosperity.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.830-836
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• 2012

Dead times appear often in describing process dynamics and raise some difficulties in simulating process dynamics or analyzing process control systems. To relieve these difficulties, it is needed to approximate the infinite dimensional dead time by the finite dimensional transfer function and, for this, the Pade approximation method is often used. For the accurate approximation of the dead time, high order Pade approximation is needed and the high order Pade approximation is not easy to memorize and is not stable numerically. We propose a method based on the continued fraction expansion that provides the same transfer functions. The method is excellent numerically as well as systematic to be memorized easily. It can be used conveniently for the process control lecture and computations.

• Design & Manufacturing
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• v.8 no.2
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• pp.30-36
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• 2014

In this study, surface deformation patterns have been investigated by the rigid-plastic finite element method for friction factor test in solid cylinder compression process. AA1100 and AA6063 aluminum alloys, which show different work hardening characteristics respectively, have been adopted as model materials used for analysis. The main objective of this study is to provide the deformation mechanics in detail in solid cylinder compression process, especially at the die/workpiece interface that is closely related with the frictional conditions. For this reason, solid cylinder compression process has been numerically analyzed. The surface flow patterns at the contact boundary have been analyzed in terms of surface expansion, surface expansion velocity, pressure distributions exerted on the die surface along the die surface. By defining bulge factor, barreling phenomenon also have been examined with calibration curves to verify their effects on the surface flow pattern that is important for evaluating the frictional condition at the interface.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.46-51
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• 2002

Cold expansion of fastener holes is a mechanical process widely used in the aerospace industry. This treatment leads to an improvement of fatigue behavior due to the developed compressive residual stresses on the hole surface. The residual stress profile depends on the parameters of cold expansion, which are expanding rate, inserting direction of mandrel, material properties dtc. Despite its importance to aerospace industiries, little attention has been devoted to the accurate modeling of the process. In this paper, three-dimensional finite element simulations have been conducted for the cold expansion in an aluminium plate in order to predict the magnitude and distribution of the residual stress. To prove the results of FE analysis, the residual strain was measured by strain gage in cold expansion test. Maximum compressive residual stress could be increase about 7 percentage using the 2-step cold expansion method.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.11-23
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• 2014

PURPOSE: The purpose of this study suggests the exercise programs for improving the function and structure by applying the Schroth exercise method and sling exercise method to the scoliosis patient. METHODS: The subjects were 16 patients who were diagnosed with scoliosis. They were randomly assigned either to a Schroth exercise group (n=8) that received Schroth exercise program or to a sling exercise group (n=8) that received sling exercise program. Flexibility, static balance, dynamic balance, and spinal angles were measured by using the modified sit and reach test, one leg standing with closed eyes, functional reach test, and Cobb's angle, respectively. The chest expansion were calculated using differences of chest circumference between maximum inspiration and maximum expiration measured under armpits, at the junction between the sternum and xiphoid process, and at the waist. RESULT: Schroth group before and after the intervention there was a difference in the static balance, spine angle, chest expansion (p<.05). sling group before and after the intervention there was a difference in the flexibility, static balance, spine angle, chest expansion (p<.05). There were significantly differences between the both groups for chest expansion thoracic level inspiratory variables at post-exercise. CONCLUSION: These results revealed that two exercise program improved flexibility, static standing balance, spine angle, chest expansion level and ability used as scoliosis management and intervention. Therefore, it is expected to be used as a method for the treatment and prevention in the process of rehabilitation of patients with scoliosis.