• Journal of Mechanical Science and Technology
• /
• v.20 no.9
• /
• pp.1339-1345
• /
• 2006

The development of an accurate and energy saving electro-pneumatic regulator that may be applied to a variety of practical pressure control applications is described in this paper. A novel modified pulse width modulation (MPWM) valve pulsing algorithm allows the electro-pneumatic regulator to become energy saving system. A comparison between the system response of conventional PWM algorithm and that of the modified PWM (MPWM) algorithm shows that the control performance is almost the same, but energy saving is greatly improved by adopting this new MPWM algorithm. The effectiveness of the proposed control algorithm is demonstrated through experiments with various reference trajectories.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1339-1342
• /
• 2005

The development of an accurate and energy saving pneumatic regulator that may be applied to a variety of practical pressure control applications is described in this paper. A novel modified pulse width modulation(MPWM) valve pulsing algorithm allows the pneumatic regulator to become energy saving system. A comparison between the system response of conventional PWM algorithm and that of the modified PWM(MPWM) algorithm shows that the control performance is almost the same, but energy saving is greatly improved by adopting this new MPWM algorithm. The effectiveness of the proposed control algorithm is demonstrated through experiments with various reference trajectories.

• Journal of the military operations research society of Korea
• /
• v.26 no.1
• /
• pp.89-99
• /
• 2000

This paper deals with a heuristic algorithm for the vehicle routing-scheduling problem to minimize the total travel distance and the total cost. Because the aim of the Clarke-Wright method, one of famous heuristic methods, is to minimize the total travel distance of vehicles, it cannot consider the cost if the cost and the travel distance is not proportional. In the Clarke-Wright method, the route of each vehicle is found by using the saving matrix which is made by an assumption that the vehicle comes back to the starting point. The problem dealt with in the paper, however, does not need the vehicle to come back because each vehicle has its hoping-start-points and hoping-destination-points. Therefore we need a different saving matrix appropriate to this occasion. We propose a method to find an initial solution by applying network simplex method after transforming the vehicle routing-scheduling problem into the minimum cost problem. Moreover, we propose a method to minimize the total travel distance by using the modified saving matrix which is appropriate to no-return occasion and the method for the case of plural types of vehicles and freights.

• Progress in Superconductivity and Cryogenics
• /
• v.21 no.2
• /
• pp.15-21
• /
• 2019

In the mine exploration sites, sustainable treatment system of mine water with energy saving and minimized chemical additives is required. Since most of the mine water contains highly-concentrated ferrous ion, it is necessary to study on the removal method of iron ions. We propose the system consisting of two processes; precipitation process by air oxidation using solid catalyst-modified magnetite and separation process combining gravitational sedimentation and magnetic separation using a permanent magnet. Firstly, in the precipitation process (a former process of the system), we succeeded to prepare solid catalyst-modified magnetite. Air oxidation using solid catalyst-modified magnetite using $Fe_2(SO_4)_3$ as a starting material showed high iron removal capability. Secondly, in the separation process (latter process of the system), solid catalyst-modified magnetite using $Fe_2(SO_4)_3$ as a starting material can be separated by a superconducting bulk magnet and a permanent magnet.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.17 no.5
• /
• pp.575-582
• /
• 1988

This paper presents an energy analysis on the VAV system of 10-story building in Seoul using DOE-2 program and Modified Bin Method. The use of VAV system is an excellent means of saving energy in new buildings and/or retrofit. The fan control techniques considered are cycling, discharge dampers, inlet vanes, and motor speed control. The monthly and annual energy consumption is calculated for fan control techniques, components, and chiller types. The results of annual fan electricity use are compared using DOE-2 and Modified Bin Method, and show fairly good agreement. In addition, factors affecting energy consumption are also described.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.14 no.3
• /
• pp.24-30
• /
• 2015

Wi-Fi STAs in power saving mode described in the Wi-Fi specification can deteriorate the system performance such as throughput, time delay when they receive data frames from a Wi-Fi AP. This problem is caused by data frame reception failure due to the channel state, and it increases re-transmissions. In this paper, we propose a modified power saving mode considering fairness of Wi-Fi system in order to solve the problem. By simulation, we showed that data throughput can be increased without time delay degradation if the proposed method restricting the number of packet transmission attempts and HARQ are used.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.5 s.236
• /
• pp.609-616
• /
• 2005

While the SIMPLE algorithm is most widely used for the simulations of flow phenomena that take place in the industrial equipments or the manufacturing processes, it is less adopted for the simulations of the free surface flow. Though the SIMPLE algorithm is free from the limitation of time step, the free surface behavior imposes the restriction on the time step. As a result, the explicit schemes are faster than the implicit scheme in terms of computation time when the same time step is applied to, since the implicit scheme includes the numerical method to solve the simultaneous equations in its procedure. If the computation time of SIMPLE algorithm can be reduced when it is applied to the unsteady free surface flow problems, the calculation can be carried out in the more stable way and, in the design process, the process variables can be controlled based on the more accurate data base. In this study, a modified SIMPLE algorithm is presented fur the free surface flow. The broken water column problem is adopted for the validation of the modified algorithm (MoSIMPLE) and for comparison to the conventional SIMPLE algorithm.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.16
• /
• pp.6983-6987
• /
• 2014

Background: Modified toluidine blue staining (MTBs) is a simple, inexpensive and time saving method to detect H. pylori in gastric biopsy specimens. As a metachromatic stain, it simultaneously highlights intestinal metaplasia, a gastric cancer precancerous lesion. The aim of this study was to assess the reliability of MTBs compared with hematoxylin-eosin (H&E) for H. pylori detection using immunoperoxidase staining as the gold standard. This technique would be beneficial for a routine diagnosis and confirmation of H. pylori eradication in developing countries where endoscopic-based approaches are dominant. Materials and Methods: Esophagogastroduodenoscopy with triple site gastric biopsies was undertaken in 207 dyspeptic patients at Thammasat University Hospital, Thailand between 1997 and 1999. H&E, MTBs and immunoperoxidase staining were applied to each specimen. The presence or absence of H. pylori with each stain was interpreted separately and the sensitivity, specificity, positive and negative predictive values of H&E and MTBs were calculated. Results: A total of 282 specimens from 207 patients were evaluated. Using immunoperoxidase staining, organisms were positive in 117 specimens (41%). MTBs proved almost equally sensitive as immunoperoxidase (99%) and significantly more sensitive than H&E (85%). It has comparable specificity (96% vs 96%), PPV (95% vs 94%), and NPV (99% vs 90%) to H&E, using immunoperoxidase staining as gold standard. MTBs compared with immunoperoxidase staining, is cheaper (2 USD vs 12 USD) and faster (20 min vs 16 hrs) compared to immunoperoxidase staining. Conclusions: MTBs is effective, economical and easy to use in daily practice for the detection of H. pylori in gastric biopsy specimens. In addition to saving time in evaluating H. pylori associated gastritis, with a high sensitivity and ability to demonstrate intestinal metaplasia, the technique may have a role in confirmation of H. pylori eradication for gastric cancer prevention in a developing country setting.

• Journal of the Korean Wood Science and Technology
• /
• v.23 no.3
• /
• pp.8-15
• /
• 1995

This analytical study was carried out to make quality and productivity up in designing the frame-type furniture with semi-rigid joint by understanding the mechanical and structural behavior of the joint and by evaluating the validity of application of the time-saving Finite Element Method to its structural analysis. Slope deflection equation for rigid joint was modified to describe the moment-rotation behavior of semi-rigid joint and the joint stiffness factor(Z) could be calculated to lessen the experimental expense. It was proved that Finite Element Analysis with imaginary elements having equivalent MOE to the semi-rigid joint could be the alternative method for the structural analysis of the frame-type furniture, comparing the internal rotation of the 2-dimensional beam-to-column model with two-pin(wooden dowel) from the finite element method with other available theoretical and experimental rotation value.

• Industrial Engineering and Management Systems
• /
• v.12 no.2
• /
• pp.161-170
• /
• 2013

Deployment of green transportation in reverse logistics is a key issue for low carbon technologies. To cope with such logistic innovation, this paper proposes a hybrid approach to solve practical vehicle routing problem (VRP) of pickup type that is common when considering the reverse logistics. Noticing that transportation cost depends not only on distance traveled but also on weight loaded, we propose a hierarchical procedure that can design an economically efficient reverse logistics network even when the scale of the problem becomes very large. Since environmental concerns are of growing importance in the reverse logistics field, we need to reveal some prospects that can reduce $CO_2$ emissions from the economically optimized VRP in the same framework. In order to cope with manifold circumstances, the above idea has been deployed by extending the Weber model to the generalized Weber model and to the case with an intermediate destination. Numerical experiments are carried out to validate the effectiveness of the proposed approach and to explore the prospects for future green reverse logistics.