• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.221-226
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• 2000

Hot air heater with light oil burner is the most common heater for greenhouse heating in the winter season in Korea. However, since the thermal efficiency of the heater is about 80∼85%, considerable unused heat amount in the form of exhaust gas heat discharges to atmosphere. In order to capture this exhaust heat a heat recovery system for plant bed heating in the greenhouse was built and tested in the hot air heating system of greenhouse. The heat recovery system is made for plant bed or soil heating in the greenhouse. The system consisted of a heat exchanger made of copper pipes, ${\Phi}12.7{\times}0.7t$ located in the rectangular column of $330{\times}330{\times}900mm$, a water circulation pump, circulation plastic pipe and a water tank. The total heat exchanger area is 1.5$m^2$, calculated considering the heat exchange amount between flue gas and water circulated in the copper pipes. The system was attached to the exhaust gas path. The heat recovery system was designed as to even recapture the latent heat of flue gas when exposing to low temperature water in the heat exchanger. According to the performance test it could recover 45,200 to 51,000kJ/hr depending on the water circulation rates of 330 to $690\ell$/hr from the waste heat discharged. The exhaust gas temperature left the heat exchanger dropped to $100^{\circ}C$ from $270^{\circ}C$ by the heat exchange between the water and the flue gas, while water gained the difference and temperature increased to $38^{\circ}C$ from $21^{\circ}C$ at the water flow rate of $690\ell$/hr. By the feasibility test conducted in the greenhouse, the system did not encounter any difficulty in operations. And, the system could recover 220,235kJ of exhaust gas heat in a day, which is equivalent of 34% of the fuel consumption by the water boiler for plant bed heating of 0.2ha in the greenhouse.

• Journal of the Korean GEO-environmental Society
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• v.8 no.3
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• pp.11-18
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• 2007

This paper studied the economical efficiency of ground source heat pump system under various conditions in apartments which have important effects on the housing market. And this study analysed the initial cost increase, saved managing cost and recovery time of initial cost. Analysis result showed as time of heating-cooling and water heating increases, the amount of saved managing cost increased much than the initial construction cost, so recovery time shortened. And as the net area of apartment increases, the recovery time increased. The study of the relation between the installation type and recovery time of initial construction cost showed when heat-cooling system adapted ground source heat and water heating system adapted waste heat, the initial construction cost was recovered most quickly. When Ground Source Heating system was used for the heating-cooling and water heating system, ground source heating system was used for the heating-cooling and waste heat used for water heating, and ground source heating system was used for the heating-cooling and LNG used for water heating, the construction cost increased 72,000, 66,900 and 62,300 won each per $m^2$ compared to the current system (package air-conditioner, heating and water heating using LNG).

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.25-32
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• 2012

Cold start driving cycles exhibit an increases in friction losses due to the low temperatures of metal components and media compared to the normal operating engine conditions. These friction losses are adversely affected to fuel economy. Therefore, in recent years, various techniques for the improvement of fuel economy at cold start driving cycles have been introduced. The main techniques are the upward control of coolant temperature and the fast warm-up techniques. In particular, the fast warm-up techniques are implemented with the coolant flow-controlled water pump and the WHRS (waste heat recovery system). This paper deals with an effect of fast ATF (automatic transmission fluid) warm-up on fuel economy using a recovery system of EGR gas waste heat in a diesel engine. On a conventional diesel engine, two ATF coolers have been connected in series, i.e., an air-cooled ATF cooler is placed in front of the condenser of air conditioning system and a water-cooled one is embedded into the radiator header. However, the new system consists of only a water-cooled heat exchanger that has been changed into the integrated structure with an EGR cooler to have the engine coolant directly from the EGR cooler. The ATF cooler becomes the ATF warmer and cooler, i.e., it plays a role of an ATF warmer if the temperature of ATF is lower than that of coolant, and plays a role of an ATF cooler otherwise. Chassis dynamometer experiments demonstrated the fuel economy improvement of over 2.5% with rapid increase in the ATF temperature.

• Resources Recycling
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• v.31 no.6
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• pp.3-17
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• 2022

The cement industry, which is an energy-intensive and high carbon dioxide emission industry, requires strategy for carbon neutrality and sustainable development. Most domestic cement companies are generating electricity by waste heat recovery system to improve energy efficiency during cement processes; however, few studies exist on recycling of energy related to this. Certain countries with high cement production researched on modifying the conventional waste heat recovery system to maximize waste heat recovery using various methods such as applying the Rankine cycle depending on the temperature, comparing working fluids, applying two or more Rankine cycles, and combining with other industries. In this study, we reviewed the research direction for energy efficiency improvement by summarizing waste heat recovery and utilization methods in the domestic and overseas cement industries.

• Nuclear Engineering and Technology
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• v.33 no.1
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• pp.1-11
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• 2001

In contrast with conventional fieldbus researches which are focused merely on real-time performance, this study aims to evaluate the real-time performance of the communication system including fault-tolerant mechanisms Maintaining performance in presence of recoverable faults is very important in case that the communication network is applied to a highly reliable system such as next generation Nuclear. Power. Plant (NPP). If the tie characteristics meet the requirements of the system, the faults will be recovered by fieldbus recovery mechanisms and the system will be safe. If the time characteristics can not meet the requirements, the faults in the fieldbus can propagate to the system failure. In this study, for the purpose of investigating the time characteristics of fieldbus, the recoverable faults are classified and then the formulas that represent delays including recovery mechanisms are developed. In order to validate the proposed approach, we have developed a simulation model that represents the Korea Next Generation Reactor (KNGR) NSSS Process Control System (NPCS). The results of the simulation show us the reasonable delay characteristics of the fault cases with recovery mechanisms. Using the simulation results and the system requirements, we also can calculate the failure propagation probability from fieldbus to outer system.

• Journal of East-West Nursing Research
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• v.16 no.2
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• pp.164-171
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• 2010

Purpose: The aim of study was to investigate relationship between compliance and recovery of patients with osteoarthritis of the knee patients after knee arthroplasty. Methods: 193 patients living in Seoul were participated in this study. Data were collected using the Knee Society Clinical Rating System and Medical Outcomes Study Short Form 36(SF-36) and analyzed by ANCOVA, t-test, and repeated measure ANOVA. Results: There was a significant difference of physiological recovery based on the number of co-morbidity patients have. Physical recovery level was different according to age, religion, and the number of co-morbidity. Age and education level of patients were different in emotional recovery. The level of physiological and physical recovery were significantly different consistent with compliance. Compared to preoperative scores, physiological and physical scores showed significant improvement at six weeks, three months, and six months after surgery while emotional scores did not showed significant improvement. Conclusion: The results of this study suggest that nursing interventions to increase compliance are needed for better recovery of patients after knee arthroplasty.

• Journal of Powder Materials
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• v.19 no.6
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• pp.405-411
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• 2012

Recovery of copper powder from copper chloride solution used in $MoO_3$ leaching process was carried out using a cementation method. Cementation is a simple and economical process, necessitating less energy compared with other recovery methods. Cementation utilizes significant difference in standard reduction potential between copper and iron under standard condition. In the present research, Cementation process variables of temperature, time, and added amount of iron scraps were optimized by using design of experiment method and individual effects on yield and efficiency of copper powder recovery were investigated using bench-scale cementation reaction system. Copper powders thus obtained from cementation process were further characterized using various analytical tools such as XRF, SEM-EDS and laser diffraction and scattering methods. Cementation process necessitated further purification of recovered copper powders and centrifugal separation method was employed, which successfully yielded copper powders of more than 99.65% purity and average $1{\mu}m$ in size.

• Journal of information and communication convergence engineering
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• v.10 no.1
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• pp.11-20
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• 2012

In a marine ubiquitous sensor network (USN) system using expensive sensors in the harsh ocean environment, it is very important to discover failures and devise recovery techniques to deal with such failures. Therefore, in order to perform failure modeling, this study analyzes the USN-based real-time water quality monitoring service of the Gaduri Aqua Farms at Songdo Island of Yeosu, South Korea and devises methods of discovery and recovery of failure by classifying the types of failure into system element failure, communication failure, and data failure. In particular, to solve problems from the perspective of data, this study defines data integrity and data consistency for use in identifying data failure. This study, by identifying the exact type of failure through analysis of the cause of failure, proposes criteria for performing relevant recovery. In addition, the experiments have been made to suggest the duration as to how long the data should be stored in the gateway when such a data failure occurs.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.1
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• pp.82-86
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• 2009

This work is design of clock and data recovery circuit using system clock. This circuit is composed by PLL(Phase Locked Loop) to make system clock and data recovery circuit. The data recovery circuit using 1/4-rate phase picking Detector helps to reduce clock frequency. It is advantageous for high speed PLL. It can achieve a low jitter operation. The designed CDR(Clock and data recovery) has been designed in a standard $0.18{\mu}m$ 1P6M CMOS technology and an active area $1{\times}1mm^2$.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.2 no.3
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• pp.25-35
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• 2004

The purpose of this study was compared to MTICs(maximal tolerated isometric contraction), decrement and recovery. For this, using isokinetic exercise analysis device(Biodex Medical Systems Inc., Biodex System 3PRO, USA), low rate(20 Hz) and high rate(100 Hz) NMES(neuromuscular electrical stimulation) were applied to the quadriceps muscles of fifteen patients with spastic hemiplegia caused by lesions in the central nervous system. The results were as follows: 1. It was shown to fast decrement in the middle of phase at low rate NMES and to slow decrement of MTIC response at high rate NMES(p<.01). 2. It was shown to fast recovery at high rate NMES and to slow recovery at low rate NMES in recovery tendency of MTIC(p<.01). These conclusions suggest that NMES of high rate caused to slow fatigue and fast recovery different from low rate NMES.