• Proceedings of the Membrane Society of Korea Conference
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• 1999.10a
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• pp.93-116
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• 1999

MF membrane element was specially designed for water purification and VSA process which can solve the fouling problem. Especially VSA process is developed for the SK Chemicals' asymmetric microfiltration hollow fiber membranes. In case of outside-to-in filtration process, MF membrane element showed the excellent flux stability caused by cleaning ability of VSA process . Simultaneous back-washing with VSA consideratbly enhances cleaning efficiency. From the result the possibility of the replacement of chemical coagulation and sand filtration process with newly developed VSA process was revealed.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.63-66
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• 1999

MF membrane element was specially designed for water purification and VSA process which can solve the fouling problem. Especially VSA process is developed for the SK Chemical's asymmetric microfiltration hollow fiber membranes. In case of outside-to-in filtration process, MF membrane element showed the excellent flux stability caused by cleaning ability of VSA process. Simultaneous back- washing with VSA considerably enhances cleaning efficiency. Form the result, the possibility of the replacement of chemical coagulation and sand filtration process with newly developed VSA process was revealed.

• Clean Technology
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• v.10 no.2
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• pp.101-109
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• 2004

PSA and VSA processes have been used broadly to produce oxygen from ambient air in midium- or small-sized plants. PSA and VSA processes are the separation methods which use difference of amount adsorbed as pressure is changed periodically, but they have the differences in pressurization and regeneration. In this study, the performance of 6-step PSA process was compared with that of 5-step VSA process with respect to purity and recovery. In addition, the effects of each step (pressurization step, adsorption step, and pressure equalization step) on purity and recovery were investigated. As a result, the VSA process using zeolite 10X showed better performance than the zeolite 5A PSA and zeolite 13X VSA process in comparison with purity, recovery and productivity. And it was enough to apply the vacuum pressure of 200 torr for the VSA, which produced over 90% oxygen with 70% recovery.

• Environmental Engineering Research
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• v.22 no.2
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• pp.169-174
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• 2017

Vacuum swing adsorption (VSA) is a promising treatment method for volatile organic compounds (VOCs). This study focuses on a VSA process for regenerating activated carbon spent with VOCs, and then investigates its adsorption capacities. Toluene was selected as the test VOC molecule, and the VSA regeneration experiments results were compared to the thermal swing adsorption process. Cyclic adsorption-desorption experiments were performed using a lab-scale apparatus with commercial activated carbon (Samchully Co.). The VSA regeneration was performed in air (0.5 L/min) at 363.15 K and 13,332 Pa. The comparative results depicted that in terms of VSA regeneration, it was found that after the fifth regeneration, about a 90% regeneration ratio was maintained. These experiments thus confirm that the VSA regeneration process has good recovery while operating at low temperatures (363.15 K) and 13,332 Pa.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.332-338
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• 2017

The objective of this work was to study the low temperature vacuum adsorption technology applicable to small and medium scale painting plants, which is the main emission source of volatile organic compounds. The low-temperature vacuum swing adsorption (VSA) technology is the way that the adsorbates are removed by reducing pressure at low temperature ($60{\sim}90^{\circ}C$) to compensate disadvantages of the existing thermal swing adsorption (TSA) technology. Commercial activated carbon was used and the absorption and desorption characteristics of toluene, a representative VOCs, were tested on a lab scale. Also based on the lab scale experimental results, a $30m^3min^{-1}$ VSA system was designed and applied to the actual painting factory to assess the applicability of the VSA system in the field. As a result of lab scale experiments, a 2 mm pellet type activated carbon showed higher toluene adsorption capacity than that of using 4 mm pellet type, and was used in a practical scale VSA system. Optimum conditions for desorption experiments were $80{\sim}90^{\circ}C$ and 100 torr. In the practical scale system, the adsorption/desorption cycles were repeated 95 times. As a result, VOCs discharged from the painting factory can be effectively removed upto 98% or more even after repeated adsorption/desorption cycles when using VSA technology indicating potential field applicabilities.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.389-392
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• 2002

Local Mechanical work is researched which spending unnecessary labors and time due to unnecessary material accumulation and fabricated on site. Accordingly, this study analyzes the work process of mechanical equipments by Lean Production principles. Value Stream Analysis(VSA) uncovers waste factor of the existing method and manufactory production method using Value Stream Mapping(VSM). In the results, this study presents improvement of the existing method problems and negative factors of manufactory production.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.6
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• pp.1480-1489
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• 1996

In ATM networks there are two methods in traffic control as schemes advancing the quality of service. One is reactive control after congestion and the other which is generally recommended, is preventive control before congestion, including connection admission control on call leel and usage parameter control, network parameter control, priority control and congestion control on cell level. In particular, usage parameter control is required for restricting the peak cell rate of bursy tracffic to the parameter negotiated at call set-up phase since the peak cell rate significantly influences the network quality of service. The scheme for progressing quality of service by usage parameter control is themethod using VSA(Virtual Scheduling Algorlithm) recommended ITU-T. The method using VSSA(Virtual Scheduling Suggested Algorlithm) in this paper is suggested by considering cell delay variation and token rate of leaky bucket, compared VSA and VSANT(Virtual Scheduling Algolithm with No Tolerance) with VSSA which polices violated cell probability of conformed peak cell rate and intentionally excessive peak cell rate. VSSA method using IPP(Interruped Poisson Process) model of input traffic source showed more quality of service than VSA and VSANT methods as usage parameter control because the suggested method reduced the violated cell probability of contformed peak cell rate and intentionally excessive peak cell rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.181-189
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• 2001

In this thesis, a policing algorithm is proposed, which is one of the traffic management function in ATM networks. The proposed algorithm minimizes CLR(Cell Loss patio) of high priority cells and solves burstiness problem of the traffic caused by multiplexing and demultiplexing process. The proposed algorithm has been implemented with VHDL and is divided into three parts, which are an input module, an UPC module, and an output module. In implementation of the UPC module\`s memory access, memory address is assigned according to VCI\`s LSB(Lowest Significant Byte) of ATM header for convenience. And the error of VSA operation from counter\`s wrap-around can be recovered by the proposed method. ANAM library 0.25 $\mu\textrm{m}$ and design compiler of Synopsys are used for synthesis of the algorithm and Synopsys VSS tool is used for VHDL simulation of it

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.416-421
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• 2001

The domestic reinforcement concrete works have mainly worked the process of re-bar fabrication/assembly on site and re-bar works affected by structural safety, durability, and schedule with form work. Accordingly, This study analyzes the process of re-bar fabrication/assembly on site to apply lean production principles to construction Value Stream Analysis(VSA) is analyzed into value-adding activity and non-value-adding activity on construction process through value analysis and Value Stream Mapping(VSM). In the results, non-value-adding activity generates waste such as the activity steps, labors, equipments, materials, time, and so on. Additionally, push-driven production is investigated making low productivity from the overproduction and so on. To resolve the problems in the process, The purpose of this paper eliminates waste factor through maximizing the value-adding activity generating value added and minimizing non-value adding activity. Particularly, it makes flow production and pull-driven production through minimizing work-in-process(WIP ).

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2327-2329
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• 2005

In this paper, we identify the memory effects of the RF high-power base station amplifiers with Vector Signal Analyzer (VSA). It is found that the model of power- amplifier using Tapped Delayed Neural - Networks with back-propagation algorithm shows very accurate modeling performance. Based on this behavioral modeling, we conducted inverse compensation process which also uses Neural Networks.