• Transactions of the Korean Society of Automotive Engineers
• /
• v.20 no.6
• /
• pp.107-116
• /
• 2012

In this study, the trucks(2.9-liter) have been developed to use DME as fuel, and performance test of the vehicle's DME engine, power, emissions, fuel economy and vehicle aspects was conducted. For experiments, the fuel system(common-rail injectors and high-pressure pump included) and the engine control logic was developed, and ECU mapping was performed. As a result, the rail pressure from 40MPa to approximately 65% increase compared to the base injector has been confirmed that. Also, the pump discharge flow is 15.5 kg/h when the fuel rail pressure is 400rpm(40MPa), and the pump discharge flow is 92.1 kg/h when the fuel rail pressure is 2,000rpm(40MPa). The maximum value of full-load torque capability is 25.5 kgfm(based on 2,000 rpm), and more than 90% compared to the level of the diesel engine were obtained. The DME vehicle was developed in this study, 120 km/h can drive to the stable, and calculated in accordance with the carbon-balance method of fuel consumptions is 5.7 km/L.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.3
• /
• pp.153-159
• /
• 2001

A system simulation program was developed for a multi-type inverter heat pump. Electronic expansion valve(EEV) was used to extend the capacity modulating range of the heat pump as expansion device. The program was also developed to calculate actual system performance with the building load variation with climate during a year. The performance variation of a multi-type hat pump with two EEV and an inverter compressor was simulated with compressor speed, capacity, and flow area of the EEV. As a result, the optimum operating frequency of the compressor and openings of the expansion device were decided at a given load. As compressor speed increased, he capacity of heat pump increased, the capacity of heat pump increased. Therefore flow area of EEV should be adjusted to have wide openness. Thus the coefficient of performance(COP) of the heat pump decreased due to increasement of compressor power input. The maximum COP point at a given load was decided according to the compressor speed. And under the given specific compressor speed and the load, the optimum openings point of EEV was also decided. Although the total load of indoor units was constant, the operating frequency increased as the fraction of load in a room increased. Finally ad the compressor power input increased, the coefficient of performance decreased.

• Journal of Digital Contents Society
• /
• v.16 no.3
• /
• pp.483-492
• /
• 2015

This thesis analysis the CARBO 3000 that is one of a $CO_2$ infuser and improve its effectiveness. The thesis designs H/W and S/W that controls the $CO_2$ infusing mass compared to the CARBO 3000. Specially the designed H/W has a newly CPU, LCD, a flow velocity controller, a solenoid valve and a flow sensor. Also the designed S/W is composed of GUI and the algorithm to control the $CO_2$ infusing mass. The designed and implemented the $CO_2$ Infuser in this thesis is tested for the performance. The commercial measuring sensor is used for the test. The testing results say that the designed and implemented the $CO_2$ Infuser in this thesis is much more accurate compared to the CARBO 3000 on $CO_2$ infusing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.513-520
• /
• 2004

A steady-state/transient performance simulation model was newly developed for the propulsion system of the CRW (Canard Rotor Wing) type UAV (Unmanned Aerial Vehicle) during flight mode transition. The CRW type UAV has a new concept RPV (Remotely Piloted Vehicle) which can fly at two flight modes such as the take-off/landing and low speed forward flight mode using the rotary wing driven by engine bypass exhaust gas and the high speed forward flight mode using the stopped wing and main engine thrust. The propulsion system of the CRW type UAV consists of the main engine system and the duct system. The flight vehicle may generally select a proper type and specific engine with acceptable thrust level to meet the flight mission in the propulsion system design phase. In this study, a turbojet engine with one spool was selected by decision of the vehicle system designer, and the duct system is composed of main duct, rotor duct, master valve, rotor tip-jet nozzles, and variable area main nozzle. In order to establish the safe flight mode transition region of the propulsion system, steady-state and transient performance simulation should be needed. Using this simulation model, the optimal fuel flow schedules were obtained to keep the proper surge margin and the turbine inlet temperature limitation through steady-state and transient performance estimation. Furthermore, these analysis results will be used to the control optimization of the propulsion system, later. In the transient performance model, ICV (Inter-Component Volume) model was used. The performance analysis using the developed models was performed at various flight conditions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the turbine inlet temperature overshoot limitation as well as the compressor surge margin. Because the engine performance simulation results without the duct system were well agreed with the engine manufacturer's data and the analysis results using a commercial program, it was confirmed that the validity of the proposed performance model was verified. However, the propulsion system performance model including the duct system will be compared with experimental measuring data, later.

• Journal of Institute of Convergence Technology
• /
• v.2 no.1
• /
• pp.24-30
• /
• 2012

In this study, the trucks(2.9-liter) have been developed to use DME as fuel, and performance test of the vehicle's DME engine, power, emissions, fuel economy and vehicle aspects was conducted. For experiments, the fuel system(common-rail injectors and high-pressure pump included) and the engine control logic was developed, and ECU mapping was performed. As a result, the rail pressure from 40MPa to approximately 65% increase compared to the base injector has been confirmed that. Also, the pump discharge flow is 15.5 kg/h when the fuel rail pressure is 400rpm(40 MPa), and the pump discharge flow is 92.1 kg/h when the fuel rail pressure is 2,000rpm(40MPa). The maximum value of full-load torque capability is 25.5kgfm(based on 2,000rpm), and more than 90% compared to the level of the diesel engine were obtained. The DME vehicle was developed in this study, 120 km/h can drive to the stable, and calculated in accordance with the carbon-balance method of fuel consumptions is 5.7 km/L.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.3
• /
• pp.13-20
• /
• 2011

In this paper, we proposed a system to raise gas safety management by using the wireless communication module and intelligent gas safety appliances. Our designed systems configure a micom-gas meter, an automatic extinguisher, sensors, and a wallpad. A micom-gas-meter monitors gas flow, gas pressure, and earthquake. An automatic fire extinguisher checks gas(combustible) leaks and temperature of $100^{\circ}C$ and $130^{\circ}C$. Sensors measure smoke and CO gas. In our novel system, a micom-gas meter cut off inner valve with warnings, an automatic fire extinguisher cut off middle valve and spray extinguishing materials, and sensors generate signals for smoke and CO when occurring gas risk. Gas safety appliances and sensors takes safety measures, and transmit those signal to a wallpad. The wallpad again transmit signal like events to a control server. Users can connect web pages for gas safety through B-ISDN and control and manage them. We hereby devised scenarios for gas safety and risk management, and demonstrated their effectiveness through experiments.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.12
• /
• pp.4721-4726
• /
• 2010

The performance characteristics of water-chilling heat pump using CO2 for the control of inverter frequency was investigated experimentally. An experimental apparatus is consisted of a compressor, a gas cooler, an expansion valve, an evaporator and a liquid receiver. All heat exchangers used in the test rig are counter flow type heat exchangers with concentric dual tubes, which are made of copper. The gas cooler and the evaporator consist of 6 and 4 straight sections respectively arranged in parallel, each has 2.4m length. The experimental results summarize as the following: for constant inlet temperature of evaporator and gas cooler, as mass flow rate, compression ratio and discharge pressure increases with the inverter frequency. And heating capacity and compressor work increases, but coefficient of performance(COP) decreases with the inverter frequency of compressor. As inlet temperature of secondary fluid in the evaporator increases from $15^{\circ}C$ to $25^{\circ}C$, compression ratio and compressor work decreases, but mass flow rate, heating capacity and COP increases with the inverter frequency of compressor. The above tendency is similar with performance variation with respect to the variation of inverter frequency in the conventional vapor compression refrigeration cycle.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.1
• /
• pp.32-37
• /
• 2011

The present study has been conducted to propose an algorithm regarding real-time load estimation of a gas engine-driven heat pump. In the study, thermal load of an indoor unit is estimated in terms of air-side and refrigerant-side. The air-side estimation is based on a typical heat exchanger model and is found to be in good agreement with experimental data. When it comes to the refrigerant-side load, a pressure difference across a valve must be estimated. For the estimation, it is assumed to be proportional to a bigger pressure difference that is available either by measurement or by estimation. Relative good agreement between the air- and refrigerant-sides suggests that the assumption may be plausible for the load estimation. The summed flow rate of all of indoor units is in good agreement with the throughput of the compressor which are calculated from the manufacturer's software. Accordingly, estimated thermal loads are also in good agreement. The proposed algorithm may be further developed for improved control algorithm and fault diagnosis.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.260-266
• /
• 2009

Non-revenue water reduction(NRW) technologies are implemented to evaluate and manage leakages scientifically in water distribution systems under local governments. A development of quantitative leakage indicator by measuring minimum night flow, pressure control policy by installation of PRV(pressure reducing valve) and the establishment of leakage prevention schemes by residual life modeling of deteriorated water pipes are reviewed and studied. Estimation models of allowable leakage are developed by measuring and analyzing minimum night flow at residential and commercial area in Nonsan city, which is suggested from UK water industry and can improve an existing leakage indicator for the evaluation of non-revenue water. Also, pressure control method is applied and analyzed to Uti distribution area in Sacheon city in the operation aspect. As results, $466\;m^3/day$ of leakage can be reduced and it is expected that 113million won of annual cost can be saved. In the part of corrosion velocity and residual life assessment, non-linear prediction models of residual thickness are proposed by assessment of corrosion velocity based on exposure years, soil and water quality etc., since the deteriorated water pipe play a major role to increase leakage. It is expected that collection data and analyzing results can be applied effectively and positively to reduce non-revenue water by accumulating surveying data and verifying the results in the business field of water distribution systems under local governments.

• Applied Chemistry for Engineering
• /
• v.10 no.8
• /
• pp.1155-1160
• /
• 1999

The screening methodology modeling, dispersion modeling procedures for continuous and instantaneous releases of the gas phase flow from the storage tank and pressure relief valve were considered. This study was performed to develop the screening methodology for prediction and control of hazardous/toxic gas releases by estimating the 1-hr average maximum ground-level concentration of $Cl_2$ gas vs. downwind distance by incorporating source term model including the general/physical properties of released material and release mode of the $Cl_2$ storage tank of the chemical plant facilities, dispersion model, and meteorological/topographical data into the TSCREEN model. As the results of the study, it was found that dispersion modes of the dense gas were affected by the state of the released material, the released conditions, physical-chemical properties of released material, and the released modes (continuous and instantaneous releases), and especially largely affected by initial (depressurized) density of the released material and release emission rate as well as the wind velocity. Especially, this study was considered to release hazardous material as meteorological data. It was thought that this screening methodology can be useful as a preliminary guideline for application of the refined analysis model by developing the generic sliding scale methodology for various senarios selected.