• Polymer(Korea)
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• v.38 no.2
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• pp.113-128
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• 2014

Tissue engineering and regenerative medicine strategies could offer new hope for patients with serious tissue injuries or end-stage organ failure. Scientists are now applying the principles of cell transplantation, material science, and engineering to create biological substitutes that can restore and maintain normal function in diseased or injured tissues/organs. Specifically, creation of engineered tissue construct requires a polymeric biomaterial scaffold that serves as a cell carrier, which would provide structural support until native tissue forms in vivo. Even though the requirements for scaffolds may be different depending on the target applications, a general function of scaffolds that need to be fulfilled is biodegradability, biological and mechanical properties, and temporal structural integrity. The scaffold's internal architecture should also enhance the permeability of nutrients and neovascularization. In addition, the stem cell field is advancing, and new discoveries in tissue engineering and regenerative medicine will lead to new therapeutic strategies. Although use of stem cells is still in the research phase, some therapies arising from tissue engineering endeavors that make use of autologous adult cells have already entered the clinic. This review discusses these tissue engineering and regenerative medicine strategies for various tissues and organs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.78-85
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• 2005

The purpose of the study was to establish the design procedure and develop the program for designing regenerative cooling system. To obtain the design parameter necessary for the realization of regenerative cooling system, water-cooled regenerative cooling system was designed from suggested procedure. To compare experimental results with a present method of analytically predicting the heat transfer loads, $250kg_{f}$ experimental LRE with water-cooled regenerative cooling system was investigated. Based on the investigation, the good correction between the predicted and measured data was verified. Developed design program can be used to designing Kerosene- cooled regenerative cooling system. The basic experimental data and correlations obtained in this study for 250kgf experimental LRE with water-cooled regenerative cooling system can be directly applicable to the real LRE.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.621-626
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• 2006

Regenerative evaporative cooling is known as an environment-friendly and energy efficient cooling method. A regenerative evaporative cooler (REC) consisting of dry and wet channels is able to cool down the air stream below the inlet wet-bulb temperature. In the regenerative evaporative cooler, the cooling effect is achieved by redirecting a portion of the air flown out of the dry channel into the wet channel and spraying water onto the redirected air. In this study, a horizontal regenerative cooler is considered. In the horizontal regenerative cooler, the flow direction of evaporating water has a right angle to the flow direction of supply air. This difference was investigated with visualization technique and simplified 2-module performance test was done in a thermo-environment chamber. Optimum design configuration is changed due to the wet channel which are easily fully covered with evaporating water and block the air flow inside the channel. Applying the optimized fin configuration design with the highly wetting surface treatment, a regenerative evaporative cooler was fabricated and tested to Identify the cooling performance improvement and operation characteristics. From the experimental results at the intake condition of $32^{\circ}C$ and 50% RH, the supply temperature was measured to be around $23.4^{\circ}C$. The cooling effectiveness based on the inlet dewpoint temperature was evaluated 73% which is almost close to the design expectation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.5
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• pp.507-511
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• 2019

The use of regenerative energy in AC drive systems has been an issue since the system became an industry standard in the 1990s. According to the quantity of the regenerative energy, the braking resistor in the case of low capacity was common. However the use of such low amount of energy is actively discussed, and the method of mounting the regenerative converter is becoming popular. In this paper, an isolated regenerative converter for reducing the circulating current which is mentioned as the biggest disadvantage of the conventional power regenerative converter system is proposed. In order to save energy, employing a power regenerative converter system for utilizing regenerative energy in an AC drive system is common. However due to the structure of the system, a circulating current is generated, which inevitably causes a decrease in efficiency. In this paper, an isolated regenerative power converter system is proposed to solve the circulating current and computer simulation to verify the possibility. The simulation results show that 20% of the circulating current of the conventional system does not appear in the proposed system, and the validity of the proposed system is confirmed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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• pp.566-573
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• 2004

Comparison of the cooling performance is provided between the desiccant cool-ing systems incorporating a direct evaporative cooler and a regenerative evaporative cooler, respectively. Cycle simulation is conducted, and the cooling capacity and COP are evaluated at various temperature and humidity conditions. The COP of the system with a regenerative evaporative cooler and the regeneration temperature of 6$0^{\circ}C$ is evaluated 0.65 at the outdoor air condition of 35$^{\circ}C$ and 40% RH. This value is found about 3.4 times larger than that of the system with a direct evaporative cooler. Furthermore, incorporating a regenerative evaporative cooler eliminates the need for deep dehumidification in a desiccant dehumidifier that is necessary to achieve low air temperature in the system with a direct evaporative cooler. Subsequently, the regenerative evaporative cooler enables the use of low temperature heat source to regenerate the dehumidifier permitting the desiccant cooling system more beneficial compared with other thermal driven air conditioners.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.669-676
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• 2007

This paper presents a new power flow method to analyze the AC electric railway system effectively in both cases of traction and regenerative braking of the trains. The algorithm to easily solve the power flow of the AC electric railway system with the trains of regenerative braking from the system without a train of regenerative braking is derived. Using this new power flow method, the voltage characteristics of a typical AC electric railway system is easily analyzed in both cases of traction and regenerative braking of the trains. We show that the presented method can be applied effectively in order to analyze the AT-fed AC electric railway system in both cases of traction and regenerative braking of the trains. A STATCOM(Static Synchronous Compensator) is applied to the system in order to improve the voltage drop problem and this case is also analyzed to show the effect of STATCOM.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1505-1510
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• 2007

In this paper, the power simulation is used for the prediction of regenerative energy and examination of install location of regenerative inverter for DC railway system. The power simulation was composed to train performance simulation(TPS) and power flow simulation. We performed the power simulation for Seoul subway line 5 and 7, calculation of regenerative energy and examination of substations where regenerative inverter is installed.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.43-55
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• 2002

Cloning by nuclear transfer in mammals using somatic cells has enormous potential applications. However, somatic cloning has been inefficient in all species in which NT is successful. High abortion and fetal death rates have been observed. These developmental defects have been attributed to incomplete nuclear reprogramming by the somatic cloning process. In this review, we will discuss studies conducted in our labs to understand the nuclear reprogramming process.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.290-292
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• 1995

In this paper, the regenerative braking control system for 4 WD Electric Vehicle (EV) is proposed. Many studies on efficient drive of EV are being done to prolong the one charge distance. By using the regenerative braking (REGEN), the resulting EV system has following advantages : a) battery is recharged with the mechanical energy of EV, b) the running load can be reduced, and consequently the efficiency can be increased. The problem of REGEN that the power acceptance ability of battery is limited can be solved by controlling regenerative braking torque. The proposed control system has following characteristics. : a) It controls regenerative power by varying mechanical braking torque. b) It controls mechanical braking torque using load torque observer. c) It controls the regenerative braking torque independently. The control scheme and simulation results are presented for the experimental car.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.166-173
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• 2005

A vehicle stability control logic for 4WD hybrid electric vehicle is proposed using the regenerative braking of the rear motor and electronic brake force distribution module. Performance of the stability control logic is evaluated for J-turn and single lane change. It is found from the simulation results that the regenerative braking at rear motor is able to provide improved stability compared with the vehicle performance without my stability control. Additional improvement can be achieved by applying the regenerative braking plus electronic brake farce distribution control. It is expected that the regenerative braking offers additional improvement of the fuel economy as well as the vehicle stability control.