• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.33 no.8
• /
• pp.299-309
• /
• 1984

This paper proposes the adapter for interrupting capacity augmentation of circuit breaker which can be applied in case of shortage in a existing circuit breaker's interrupting capacity due to utility system extension. The adapter utilizes two winding type of reactor instead of single winding type of reactor and the control of 2ry circuit is excuted by a triac interlocked with the system protective relays actuation so as to cut out the reactor by short circuit of the 2ry winding in normal situation and to cut in the reactor by open circuit of the 2ry winding in abnomal situation such as short circuit accident. As a result of the theoritical analysis and experiment, it is proved that the adaptor can reduce the voltage crop and iron loss due to the reactor signigicantly in normal system condition and do a role of reactor upon the power system accident.

• Journal of Energy Engineering
• /
• v.10 no.4
• /
• pp.357-362
• /
• 2001

A bench type ammonia-water absorber heat exchange cycle was tested by varying the system charging concentration, refrigerating valve opening and weak solution flow rate. It was observed that the cooling capacity was increased as the system charging concentration was increased. Optimum system charging concentration was found for the coolong capacity of the system. The opening rate of refrigerant expansion valve had a direct influence on the refrigerant sub-cooling at the condenser outlet. Optimum sub-cooling was found to be 0~4$^{\circ}C$. As the weak solution flow rate increased the concentration of strong solution and the evaporating pressure decreased. There existed a optimum weak solution flow rate which maximized the cooling capacity and COP.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.143-145
• /
• 2005

There has been increasing interest in the renewable energies. Wind energy is worldwide number one renewable energy from the installed capacity viewpoint. Most of the power systems utilizing wind energy are connected to other large systems. In such integrated systems, frequency control is not big issue. Rut the situation is different in isolated systems like Korean power system. It is important to assess appropriate capacity of wind power for our system, as it affects the system operation and control strategy. In this paper we made it clear the relationship among generator inertias, governor droop, system damping and wind energy capacity.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.6
• /
• pp.1011-1016
• /
• 2010

It is an important issue to electric power system operations that it can reliably supply large-capacity power to consumption area as due to increasing power demand growth. For this purpose, The FACTS equipment based on Power IT technology with the existing mechanical compensators has been applied to power system. Therefore we suggest on this paper that a plan for coordination control of multiple power compensation equipment in order to increase the utilization of each facility and secure operation margin capacity. As the result of simulation, it is possible to cope actively with a suddenly changed power system. This helps greatly for the voltage stability and supply reliability in a suddenly changed power system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.6
• /
• pp.427-433
• /
• 2007

Generally, H.V.A.C load capacity in early planning phase can presume with maximum thermal load. Basic data can prove by air conditioning equipment system data analysis at existing building. There are poor and not reliable alternative presentation. In this paper, measured data after use H.V.A.C load calculation K-load program reply choosing standard building and variables simulation. And I founded peak load correlation graph and mode for several kinds of variable and contents of size. I wish that equipment designer is beaconed to produce optimum capacity at building as quantitative through this result.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.239-241
• /
• 2010

Performance evaluation for an air conditioning system is conducted at a specified test conditions. One is low temperature and the other is high temperature condition. Most of the manufactures tried to improve the performance at higher outdoor temperature. One of the reasons is that the customer wants to get ore capacity at high temperature climate. To cope with these kinds of demand, manufactures are tried to achieve higher capacity at high temperature with minimum power consumption even with same size of the system. Consequently, previous studies on performance of the air conditioning system are focused on capacity and performance improvement at high outdoor temperature.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.138-141
• /
• 1999

New solutions are given for the capacity and spectrum efficiency of frequency hopped spread spectrum multiple access system(FH-SSMA) in a Nakagami interference environment. In this paper we derive a exact formulation of the deletion probability for a mobile environment and analyze the system capacity and spectrum efficiency in terms of the average bit error rate(BER). It is shown that the system capacity is decreased by 52% as the Nakagami fading parameter is reduced to 0.5 and the required signal to noise ratio(SNR) is above 25dB, to get the spectrum efficiency of 0.3.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.241-244
• /
• 2006

In this paper, we suggest the high efficient control method based on general PI control law to control the refrigeration system of the ship effectively. In the variable speed refrigeration system, the capacity and the superheat are controlled by inverters and electronic expansion valves respectively for saving energy and improving cost performance. Thus, we propose decoupling model to eliminate the interfering at first. Next, we design PI controller to control capacity and superheat independently. Finally the control performance was investigated through some experiments. The experiments results show that the PI control design can obtain good control performance deal with the varied control reference and thermal load.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.3
• /
• pp.302-310
• /
• 2008

In order to evaluate the nominal rating of breakers in distribution system due to the increased capacity and operating conditions of power transformers in 154 kV substation, the fault currents in distribution system were calculated by the conventional method and simulations of PSCAD/EMTDC program. Consequently, under the condition of the parallel operation of transformers, the fault currents exceed the nominal current of the breakers in some areas. Without NGR at the secondary neutral of the transformer, the current of single line-to-ground fault was bigger than that of 3-phase fault. Therefore, the results clearly show that the measures to limit the fault currents in distribution system are needed when the increased capacity of power transformers is introduced into 154 kV substation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.3
• /
• pp.401-413
• /
• 1999

An ice storage cooling facility with cooling capacity of 150㎾ has been constructed for the purpose of developing optimal design and control strategy for an ice storage system. As the first step to this purpose, a computer program has been developed to simulate the operation of the ice storage system and examined precisely by comparing the results with those measured from the test facility. With the simulation program verified from the comparison, a design procedure has been developed to determine the minimum capacity required for each operation strategy available commercially. It is shown that the minimum sizes of the chiller and the storage tank are strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream.