• Journal of Power Electronics
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• 제7권2호
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• pp.118-123
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• 2007

This paper presents a new ZCS-PWM high frequency inverter. Zero current switching operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. Dual duty cycle control scheme is used to provide a wide range of high frequency AC output power regulation that is important in many high frequency inverter applications. It found that a complete soft switching operation can be achieved even for low power setting ranges by introducing high-frequency dual duty cycle control scheme. The proposed high frequency inverter is more suitable for consumer induction heating(IH) applications. The operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• 한국기계기술학회지
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• 제13권1호
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• pp.113-118
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• 2011

To analyze and verify the effect of replacing thermal storage heater by a cascade cycle heat pump using midnight electricity was installed and tested at a customer's house in Wonju, Korea. The electric night storage heater is consist of 30kW electric heater and 2,700 liters of thermal storage water tank to supply hot water for warming house floor. The power for electric heater was cut off and hot water was only generated by cascade cycle heat pump. Current thermal storage water tank was not eliminated and electric heater wiring was modified. Some operation logic of the heat pump was also modified for proper operation. The required capacity of the heat pump and hot water temperature for given warming condition were estimated. The estimated capacity of heat pump was about 19kW and estimated hot water temperature for proper heating was at least $75^{\circ}C$.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.584-589
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• 2006

In this paper, a test apparatus for reliability evaluation of a rotary compressor has been suggested with a short-cycle concept. $CO_2$ refrigerant is adopted for this cycle to avoid phase change during cycle operation. Evaporator is not necessary in short-cycle. Utilizing a short-cycle, the test apparatus was built on the purpose of evaluating the reliability of each rotary compressor on the conveyer belt of the factory. The primary validation of the test apparatus is discussed by analyzing the experimental heat balance data. Additional validation was performed through the overload continuous operation test where the wear rate of the $CO_2$ short-cycle was found to similar to that of the R22 normal-cycle. The reliability evaluation test apparatus with a short-cycle in present investigation was found simple and efficient in the view of reducing sample numbers, costs, and test time in analyzing the reliability of rotary compressors.

• 전기학회논문지
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• 제62권11호
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• pp.1610-1616
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• 2013

Recently, district heating and cooling (DHC) systems based on combined cycle generation (CCG) providers are increasing in Korea. Since characteristics of combined heat and power (CHP) generators and heat demands of providers, heat trading between DHC providers based on the economic viewpoint is required; the heat trading has been doing. In this paper, a mathematical model for optimal operation based on heat trading between DHC providers is proposed. Especially, start-up characteristic of CCG is included. The operation model is established by mixed integer linear programming (MILP).

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.198-205
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• 2009

일반적으로 철도차량은 획득비용보다 운영 유지보수비용이 높다는 것이 알려져 있다. 운영 유지보수비용의 절감을 위해서는 운영 유지보수 비용 측면에서 효율적으로 설계된 철도차량을 획득하는 것이 매우 중요하다. 따라서 철도차량의 획득단계에서부터 운영 유지보수비용을 포함한 수명주기비용을 고려하는 것이 필요하다. 본 연구는 철도차량의 획득단계에서 수명주기비용을 고려하기 위한 절차 및 수명주기비용 모형을 제시한다.

• 전기학회논문지
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• 제66권6호
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• pp.905-910
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• 2017

As the development of BESS(Battery Energy Storage System), the application of BESS in load frequency control is considered as effective method. So, KEPCO(Korea Electric Power Corporation) have installed about 236MW ESS for GF(Govner Free) function from 2014. In this paper, we implemented Simulink Model for KEPCO GF ESS and analyzed one year historical operation data generated by Simulink model and actually measured frequency data. The operation results were divided into action for maintaining SOC and frequency. In addition, we also analyzed cycle life of GF ESS using two ESS cycle life model. We concluded the ESS cycle life models are not appropriate, because Most of the SOC swing in operation results are below 10%.

• 상하수도학회지
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• 제13권4호
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• pp.54-61
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• 1999

SBR process used to evaluate the removal of organics, nitrogen and phosphorus on the basis of a report of research on a precedence at various operation cycle and condition change. Effluent concentration of COD were 50mg/l, 50mg/l, 90mg/l respectively, The removal rates of COD were nearly over 95% at Run 1, 2 and 4. But at Run 3, Effluent concentration of COD was 255.0mg/l, The removal rate of COD was 87% at Run 3. As Oxic/Anoxic rate was fixed and operating cycle of Oxic/Anoxic was changed, the removal rates of T-N were 74.7%, 46.9%, 28.5%, 63.3% respectively at Run 1~4. The case of Run 1 was best result. The removal rates of T-P was appeared in proportion to T-N removal rates and rest of $NO_2-N$. The removal rates of T-P were 51.2%, 35.5%, 41.5%, 51.9% respectively. The removal rates of COD, T-N, T-P were influenced on the change of SBR operation cycle. As organic loading rate was $1.43kgCOD/m^3day$ and C/N ratio was 3.0, operation cycle of Run 1 was best condition of T-N removal rates and T-P removal.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.129-131
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• 2006

This paper presents a new ZVS-PWM high frequency inverter. The ZVS operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. The operating principle and the operating characteristics of the new high frequency circuit treated here are illustrated and evaluated on the basis of simulation results. It was examined that the complete soft switching operation can be achieved even for low power setting ranges by introducing the high frequency dual duty cycle control scheme. In the proposed high frequency inverter treated here, the dual mode pulse modulation control strategy of the asymmetrical PWM in the higher power setting ranges and the lower power setting ones, the output power of this high frequency inverter could introduce in order to extend soft switching operation ranges. Dual duty cycle is used to provide a wide range of output power regulation that is important in many high frequency inverter applications. It is more suitable for induction heating applications the operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• Smart Structures and Systems
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• 제16권4호
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• pp.743-758
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• 2015

This paper presents an advanced life cycle cost (LCC) analysis of a ground source heat pump (GSHP) system and suggests a smart operation mode with a thermal performance test (TPT) and an energy pile system constructed on the site of the Incheon International Airport (IIA). First, an economic analysis of the GSHP system was conducted for the second passenger terminal of the IIA considering actual influencing factors such as government support and the residual value of the equipment. The analysis results showed that the economic efficiency of the GSHP system could be increased owing to several influential factors. Second, a multiple regression analysis was conducted using different independent variables in order to analyze the influence indices with regard to the LCC results. Every independent index, in this case the initial construction cost, lifespan of the equipment, discount rate and the amount of price inflation can affect the LCC results. Third, a GSHP system using an energy pile was installed on the site of the construction laboratory institute of the IIA. TPTs of W-shape and spiral-coil-type GHEs were conducted in continuous and intermittent operation modes, respectively, prior to system operation of the energy pile. A cooling GSHP system in the energy pile was operated in both the continuous and intermittent modes, and the LCC was calculated. Furthermore, the smart operation mode and LCC were analyzed considering the application of a thermal storage tank.

• Smart Structures and Systems
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• 제13권3호
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• pp.407-418
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• 2014

The purpose of this paper is to present an Integrated Life Cycle Bridge Information Modeling that can be used throughout different phases of the bridge life cycle including: design, construction, and operation and maintenance phases. Bridge Information Modeling (BrIM) has become an effective tool in bridge engineering and construction. It has been used in obtaining accurate shop drawings, cost estimation, and visualization. In this paper, BrIM is used as an integrated tool for bridges life cycle information modeling. In the design phase, BrIM model can be used in obtaining optimum construction methods and performing structural advanced analysis. During construction phase, the model selects the appropriate locations for mobile cranes, monitors the status of precast components, and controls documents. Whereas, it acts as a tool for bridge management system in operation and maintenance phase. The paper provides a detailed description for each use of BrIM model in design, construction, and operation and maintenance phases of bridges. It is proven that BrIM is an effective tool for bridge management systems throughout their life phases.