• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.12
• /
• pp.1039-1046
• /
• 2002

To investigate the characteristics of orifice as an expansion devices, the experimental apparatus was made and experiments are being peformed using R22 and R290. The main idea of this control method of refrigerant flow rate with coupled orifices is to control the ON/OFF state of T and Ball type orifice corresponding to the subdivided region of thermal load. When system requires minimum thermal load, both T and Ball type orifices are closed, but refrigerant can flow through small hole of T type orifice. In regular thermal load, when ball type orifice is closed, T type orifice is opened and mass flow rate increase more than OFF state of T type orifice, due to large diameter. In maximum thermal load, both T and Ball type orifices are open and the much refrigerant can flow. The flow characteristics on T type orifice and parallel-combined orifice are obtained in the subdivided region of thermal load.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.929-931
• /
• 2002

For design of On/Off type solenoid actuator, designer must have the experimental knowledge as well as general electromagnetic formulas to design object. It is possible for theoretical knowledge to do the out-line design, but it is impossible to optimal design without experimental knowledge which only can achieve through many repeated experiments. In addition, in present On/Off type solenoid actuator field, smaller, lightening, lower consumption power, high response time are effected as the most important design factor. So, experimental knowledge is more needed for optimal design of solenoid actuator. In this study, we developed a design program composed electromagnetic theories and experimental parameter values for inexperienced designers. And we proved the propriety of this program by experiments.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.4
• /
• pp.763-769
• /
• 2009

A series voltage compensation(SVC) system is a power-electronics controller that can protect sensitive loads from disturbance in the supply system. Especially, voltage sags are considered the dominant disturbances affecting the power quality. This paper dealt with a system of off-line type voltage sag compensation by using a bi-directional DC/DC converter of environmentally friendly ultra-capacitor. This capacitor is attached to the DC link of SVC through the high-efficiency DC/DC converter in order to compensate the DC link voltage drop during short-term power interruption as voltage sags. Therefore, in this paper, a DC/DC converter to control high-efficiency energy of ultra-capacitor and voltage sag detection algorithm of off-line type SVC systems are newly introduced. According to the results of experimental of prototype system, it is verified that the proposed system has effectiveness of voltage sag compensation using an ultra-capacitor.

• Journal of Microbiology and Biotechnology
• /
• v.8 no.2
• /
• pp.165-170
• /
• 1998

Lipase-catalyzed esterification of n-butyl oleate was carried out in n-hexane as a model reaction. The optimal activity of Candida rugosa lipase was shown in a water activity ($a_w$) range of 0.52 to 0.65 at $30^{\circ}C$. The water produced from the esterification was removed by a tubular type pervaporation system. The rate of ester formed from the enzymatic esterification was allowed to be the same as the rate of water removal by maintaining an optimal $a_w$ of the reaction system using an on-off dewatering control device. The reaction rate and yield with a$a_w$ control were increased two folds higher than the respective values for the uncontrolled reaction.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.2
• /
• pp.119-126
• /
• 2008

In this study, the characteristics of the hydraulic control system with bleed-off center type of a compact excavator were analyzed using developed analysis program. From the parametric analysis, the effects of each factor were revealed. Through the simulation with varying parameters, the system parameter effects on the controllable region and the pump pressure and load pressure variations were studied. The results were compared with the experimental ones. The results and discussions of the present paper could aid in the performance improvement of a hydraulic control system of a compact excavator.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1709-1712
• /
• 2003

Almost the on-off type solenoid valve is used to hydraulic system. It has a strong point that concerned about rapid response, electric and hydraulic characteristic at the same time. In this paper we produced the new type spool using the MR fluid different from the others. Also we controlled a cylinder position through PWM method. And using the AMESim software, We compared our new type spool valve with existed one from data of simulation and experiment.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.6
• /
• pp.995-998
• /
• 2007

Pentacene moiety has been widely studied in Organic Thin-Film Transistor (OTFT) device as a channel layer because of high carrier mobility. In this study, we have fabricated vertical type Organic Static Induction Transistors (SITs) using pentacene, 6,13-Dinaphthalen-1-ly-Pentacene (1-DNP, 3), and 6,13-Dinaphthalen-2- ly-Pentacene (2-DNP, 4). 1-DNP and 2-DNP have same naphtyl group with pentacene, but different linked position and spatial arrangement. We have checked the static characteristics of materials in vertical type SITs device. We found that pentacene has as on/off ratio of 14.56, 1-DNP and 2-DNP shows as on/off ratio of 36.58 and 6.61 at VDS = 2V in SIT, respectively.

• Proceedings of the KIEE Conference
• /
• 1995.07a
• /
• pp.274-277
• /
• 1995

Recent environmental pollutions have intensified the need to develop zero emission vehicles. The most effect method of such solutions is EV. EV is high energy efficiency, easy to maintain, repair and is possible to make high performance control. However, because energy density of batteries is constrained and the distance covered one charge is short range. Also because EV has disadvantage of poor accelation ability, development of high performance battery is required for large scale use of EV. EV charger analogous to gas apparatus must also be developed immediately. Charger is discriminate between on-vehicle type and off-vehicle type. As off-vehicle type is able to charge fast and safe, inductive charging is considered. This paper aims to develope off-vehicle inductive charging system. Therefore, it achieved power factor correction converter, high frequency DC/AC inverter control algorithm development which gives proof validity through simulation and formulated the basic concept of high frequency transformer design for inductive charging.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.167-170
• /
• 2009

Fast cook-off test with rocket motors was performed and characteristics of the results were analyzed. The material of the motor case was carbon epoxy composite. The motor was loaded with HTPE propellants to improve the insensitive munitions characteristics. In the tests, sound pressure and heat flux sensors were used to determine the category of response according to the standard. The reaction response of all of the HTPE motors tested by fast cook-off was judged as Type V burning.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.694-697
• /
• 2003

In applying LCD to TV application, one of the most significant factors to be improved is image sticking on the moving picture. LCD is different from CRT in the sense that it's continuous passive device, which holds images in entire frame period, while impulse type device generate image in very short time. To reduce image sticking problem related to hold type display mode, we made an experiment to drive LCD like CRT. We made articulate images by turn on-off backlight, and we realized the ratio of Back Light on-off time by adjusting between on time and off time for video signal input during 1 frame (16.7ms). Conventional CCFL (cold cathode fluorescent lamp) cannot follow fast on-off speed, so we evaluated new fluorescent substances of light source to improve residual light characteristic of CCFL. We realized articulate image generation similar to CRT by blinking drive. As a result, reduced image sticking phenomenon was validated by naked eye and response time measurement.