• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.606-611
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• 2007

Pulsation is an inherent phenomenon in reciprocating compressors. It interacts with piping to cause vibrations and performance problems. Indiscriminately connecting to a compressor can be dangerous and cost money in the form of broken equipment and piping, poor performance, inaccurate metering, unwanted vibration, and sometimes noise. Piping connected to a compressor can materially affect the performance and response. To minimize these detrimental effects, reciprocating compressor system should be equipped by pulsation suppression system. This study discusses pressure pulsation phenomena occurred in a reciprocating compressor system. An experiment applied air compressor unit, as pulsating pressure generator, has been done. The compressor was connected sequentially to a snubber model and pressure tank. Sensor probes were placed on the inlet and outlet pipes of snubber. Compressor was driven by a motor controlled by a frequency regulator. The experiment was conducted by adjusting the regulator at 40Hz. General information about an internal gas flow can be achieved by numerical analysis approach. Information of the velocity, pressure and turbulence kinetic energy distribution are presented in this paper. Based on this result, the design improvement might be done.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.734-741
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• 2004

Boundary layer ingestion in airframe-integrated scramjet engines causes engine stall (“engine un start” hereafter) and restricts engine performance. To improve the unstart characteristics in engines, boundary layer bleed and a two-staged injection of fuel were examined in Mach 4 and Mach 6 engine tests. A boundary layer bleed system consisting of a porous plate, an air coolers, a metering orifice and an ON/OFF valve, was designed for each of the engines. First, a method to determine bleed rate requirements was developed. Porous plates were designed to suck air out of the Mach 4 engine at a rate of 200 g/s and out of the Mach 6 engine at a rate of 30 g/s. Air coolers were then optimized based on the bleed airflow rates. The exhaust air temperature could be cooled below 600 K in the porous plates and the compact air coolers. The Mach 4 engine tests showed that a small bleed rate of 3% doubled the engine operating range and thrust. With the assistance of two-staged fuel injection of H2, the engine operating range was extended to Ф0.95 and the maximum thrust was tripled to 2560 N. The Mach 6 tests showed that a bleed of 30 g/s (0.6% of captured air in the engine) extended the start limit from Ф0.48 to Ф1 to deliver a maximum thrust of 2460 N.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.50-64
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• 2016

Nowadays, smart meter (SM) technology is widely effectively used. In addition, power allocation (PA) and channel selection (CS) are considered problems with many proposed approaches. In this paper, we will suggest a specific scenario for an SM configuration system and show how to solve the optimization problem for transmission between SMs and the data concentrator unit (DCU), the center that collects the data from several SMs, via simulation. An efficient CS with PA scheme is proposed in the TV white space system, which uses the TV band spectrum. On the basic of the optimal configuration requirements, SMs can have a transmission schedule and channel selection to obtain the optimal efficiency of using spectrum resources when transmitting data to the DCU. The optimal goals discussed in this paper are the maximum capacity or maximum channel efficiency and the maximum allowable power of the SMs used to satisfy the quality of service without harm to another wireless system. In addition, minimization of the interference to the digital television system and other SMs is also important and needs to be considered when the solving coexistence scenario. Further, we propose a process that performs an interference analysis scheme by using the spectrum engineering advanced Monte Carlo analysis tool (SEAMCAT), which is an integrated software tool based on a Monte-Carlo simulation method. Briefly, the process is as follows: The optimization process implemented by genetic evolution optimization engines, i.e., a genetic algorithm, will calculate the best configuration for the SM system on the basis of the interference limitation for each SM by SEAMCAT in a specific configuration, which reaches the solution with the best defined optimal goal satisfaction.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.171-180
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• 2012

In the development of MDMS(Meter Data Management System) based on CIM(Common Information Model), which is international standard in information model and data exchange on power system, the two focused issues are the effective management of data collected in a shorter time period and the way to integrate services supporting legacy system to use the AMI(AMI, Advanced Metering Infrastructure) data. In this paper, we propose MDMS implementation methods and functions in AMI environment which are differ from existing AMR system environments in that the methods support bi-directional service infrastructure. The proposed MDMS in this paper has two unique features, one is the secure of interoperability by utilizing the CIM and ESB, the other is the improvement of field application by implementing system module based on components. On an implementation of smart grid, the result of proposed methods is expected to contribute to the efficient development and operation of CIM-based power system.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.106-113
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• 2009

This study was carried out to test feasibility of a granule fertilizer applicator for rapeseed seeding in paddy fields. The metering plate of a conventional applicator was modified for rapeseed seeding. The modified plate had new three seeding openings with total area of $342mm^2$. Average target discharging rates ranged from 6.3 to 21.0 g/s and correlated with opening areas. Application patterns of the rapeseed seeding showed M-shape. The coefficients of variation of the application showed 70.5% at 0.99 m/s of forwarding speed and 14.3 g/s of a discharge rate, and 77.7% at 1.72 m/s of a forwarding speed and 8.23 g/s of a discharge rate. The coefficients of variation in the direction of transverse of the tractor ranged from 7.3 to 47.7%. In rapeseed seeding tests using the applicator, seed damages rates were less than 15% due to the agitator, the seed hopper and the seeding plate break. Therefore, improvements of the applicator blow heads and seeding equipments were required in order to apply rapeseed efficiently.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.70-79
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• 2016

Satrec Initiative successfully developed a high-resolution electro-optical camera system, EOS-D Ver.1.0. EOS-D Ver.1.0 is the main payload of DubaiSat-2 and Deimos-2, which are developed based on the SI-300 platform of Satrec Initiative. After the launch and early operation (LEOP) of DubaiSat-2 and Deimos-2, we performed refocusing for the telescope of EOS-D Ver.1.0 to compensate for the dimensional change of its metering structure by moisture out-gassing. Before and after refocusing, we conducted the performance evaluation of thermal control system(TCS) for EOS-D Ver.1.0 using the in-orbit telemetry data. The evaluation showed EOS-D Ver.1.0 was under well-controlled thermal environment, which demonstrates TCS was designed and developed to meet all requirements.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.193-200
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• 2009

This paper investigated the drop characteristics of oleo pneumatic type landing gear for small aircraft and the effects of cavitations in modeling the landing gear system. The landing gear system employed a simple oleo pneumatic type damper without a metering pin. In general, oleo-pneumatic type landing gears are light-weighted because of it's simplicity, yet they offer excellent impact absorption characteristics. In this study, the landing gear system was modeled using MSC ADAMS, which offers a drop simulation module. After modeling the system, a series of testing was conducted, using a prototype landing gear system, to validate the analysis model and simulation results. The effect of cavitation was considered in the simulation model to obtain a better correlation between the test and simulation results. The results show that adding the cavitation effect in the simulation model significantly improved the simulation model and better captured the dynamic behaviors of the landing system. Using the 'cavitation' model, dynamics characteristics of the landing gear were further evaluated for other landing conditions, such as landing in various angles of slopes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1216-1223
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• 2018

As field of application of AMI, AMR uses the power line as the primary means of communication. PLC has a big merit without installation of the new network for communication in a field using the power line which is the existing equipment. However, there is a serious obstacle in commercialization for the instability by noise and communication environment. Therefore, the technical method for maintaining the communication state which overcome such demerit and was stabilized is required essentially. PLC routing technology is applied with the alternative plan now. The routing technology currently managed by field includes many problems by applying the algorithm of an elementary level. PLC routing path search problem can be modeled with the problem of searching for optimal solution as similar to such as optimal routing problem and TSP(Travelling salesman problem). In this paper, in order to search for a PLC routing path efficiently and to choose the optimal path, GA(Genetic Algorithm) was applied. Although PLC was similar in optimal solution search as compared with typical GA, it also has a difference point by the characteristic of communication, and presented the new methodology over this. Moreover, the validity of application technology was verified by showing the experimental result to which GA is applied and analyzing as compared with the existing algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2113-2119
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• 2006

In this paper, we design the r-Sensor protocol for reliable data transmission in the Intelligent Home Service based on the wireless sensor network environment. The r-Sensor protocol improve the reliability of data transmission and node fairness using simple routing algorithm, congestion control, and loss recovery method that minimize the load of relay node. Reposed routing algorithm find out upstream and downstream nodes using the Network Management packet. Meanwhile, loss recovery algorithm uses the Aggregated-Nack. To apply supposed algorithm, the IHS-AMR(Intelligent Home Service - Automatic Meter Reader) and sensor node are designed and implemented in hardware. The IHS-AMR provides remote metering service and also offers home safety service by internetworking with sensor network, mobile phone network and internet.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.3
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• pp.7-16
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• 1997

The constituents of deposits on paper machine and holes/spots in paper have been studied by consequently a combination of analytical techniques, such as FTIR, Py-GC-MS, and. EDS. FTIR spectroscopy was used prior to Py-GC-MS and EDS analysis, as preliminary analysis technique. The analysis of organic components were carried out with the use of a pyrolysis unit connected to a GC-MS, and inorganic components in ash were analysed by SEM equipped with an EDS analyzer after pyrolysis at 59$0^{\circ}C$. The deposits on the dryer section were complex pitch, which was the mixture of the organic contents of fatty acid ester and starch, and the inorganic contents of talc, clay, and calcium carbonate. The complex pitch was estimated to come from the coated broke. We knew the deposits on the metering rod of sym-sizer were associated with the interaction of unstable AKD and CaCO$_3$. The compositions of holes or spots varied considerably and were associated with chemical interaction within the system. The holes, spots, and blotches in the finished paper were PE and PP that were streamed out from pulp sources, complex pitch that were caused by the interaction of the different additives in the system, polymer such as flexible PVC that used for the prop of palette, and hot melt as adhesives that came from the inadequate handling of broke. In addition, we identified that poly(caprolactam) which is used for forming fabrics or press felts, could be mixed with the raw materials by accident and results in streak on coating.