• Plant Journal
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• v.12 no.1
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• pp.29-36
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• 2016

It is becoming increasingly important to make use of alternative energy source. because It is not able to rely on only fossil fuel for the recent increasing demand of energy consumption. With this situation, lots of studies for utilizing low grade energy such as industrial waste heat, solar energy, and geothermal energy have been conducted. The aim of this study is to predict the operation characteristics of working fluid by using performance analysis program (ThermoFlex) through the system analysis which is not mixing district return water but using ORC(Organic Rankine Cycle, hereinafter ORC) as a downstream cycle when accumulating district heating (hereinafter DH). In this study, We conducted the performance analysis for the case which has the district heating water temperature($120^{\circ}C$) and Flow rate of $163m^3/h$ (including District Heating return water flow), and examined several working fluid which is proper to this temperature. The case using R245fa (which is the best-case) showed 269.2kW power output, 6.37% efficiency. Additionally, Cut down on fuel was expected because of the boiler inlet temperature increase by being Formed $57.3{\sim}85^{\circ}C$ in a temperature of district heating return water, depending on a pressure change of a condenser in ORC system.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.41-47
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• 2017

This study aimed to analyze organic Rankine cycle(ORC) which recovers discarded heat from a gas turbine based combined cycle cogeneration(CC-cogen) plant in terms of both performance and economics. The nominal electric power of the CC-cogen plant is around $120MW_e$, and heat for district heating is $153MW_{th}$. The major purpose of this study is to compare various options in selecting heat source of the ORC. Three heat sources were compared. Case 1 uses the exhaust gas from the HRSG, which is purely wasted to environment in normal plant operation without ORC. Case 2 also uses the exhaust gas from the HRSG. On the other hand, in this case, the DH economizer, which is located at the end of the HRSG, does not operate. Case 3 generates power using some of the district heating water which is supplied to consumers. The estimated ORC power generation ranges between 0.3 to 2.3% of the power generation capacity of the CC-cogen plant. Overall, Case 3 is evaluated to be better than other two options in terms of system design flexibility and power generation capacity.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.2
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• pp.234-241
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• 2020

This paper presents a thermodynamic performance analysis of a combined cycle consisting of regenerative organic Rankine cycle (ORC) and liquefied natural gas (LNG) Rankine cycle to recover low-grade heat source and the cold energy of LNG. The mathematical models are developed and the system performances are analyzed in the aspect of thermodynamics. The effects of the turbine inlet pressure and the working fluid on the system performance such as the mass flow rates, heat transfers at heat exchangers, power productions at turbines, and thermal efficiency are systematically investigated. The results show that the thermodynamic performance of ORC such as net power production and thermal efficiency can be significantly improved by the regenerative ORC and the LNG cold energy.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.6
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• pp.768-773
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• 2012

This study was performed to find out the possibility that hot waste water from a thermoelectric power plant can be applied to Organic Rankine Cycle (ORC) by comparing the performance characteristics for use of the ocean surface water ($25^{\circ}C$) and hot waste water ($35^{\circ}C$) as a secondary fluid. The parameters considered in this study are four; superheating temperature, subcooling temperature, turbine efficiency, and pump efficiency. Main results of this study are summarized as follows : Overall efficiency of applying hot waste water to ORC is 87% higher than that of surface water. Thus it could be confirmed that hot waste water of the thermoelectric power plant can be applied to ORC.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.699-705
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• 2011

A combined heat and power cogeneration system driven by low-temperature sources is investigated by the first and second laws of thermodynamics. The system consists of Organic Rankine Cycle (ORC) and an additional process heater as a series circuit. Seven working fluids of R152a, propane, isobutane, butane, R11, R123, isopentane and n-pentane are considered in this work. Maximum mass flow rate of a working fluid relative to that of the source fluid is considered to extract maximum power from the source. Results indicate that the second-law efficiency can be significantly increased due to the combined heat and power generation. Furthermore, higher source temperature and lower turbine inlet pressure lead to lower second-law efficiency of ORC system but higher that of combined system. Results also show that the optimum working fluid varies with the source temperature.

• International Journal of Advanced Culture Technology
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• v.3 no.2
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• pp.67-76
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• 2015

This paper aims to study and design of Organic Rankine Cycle (ORC) Machine using Isopentane as working fluid expanding through Tesla turbine. The study on ORC machine expanding through Tesla turbine has result on the efficiency of Tesla turbine. In addition, Thermodynamics theory on isentropic efficiency proved to be a successful method for overcoming the difficulties associated with the determination of very low torque at very high angular speed. By using an inexpensive experiment device and a simple method, the angular acceleration method, for measuring output torque and power in a Tesla turbine is able to predict a tendency of output work. The experiments using two Tesla turbine sizes, the first size is 1.6 bigger than the second one. In comparison with the first size, the tesla turbine can produce power output more than 62% of the second size. Further study on the machine can be developed throughout the county due to its low cost and efficiency.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.269-272
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• 2005

무선 네트워크 이동성 기술에 대한 연구가 수년간 진행되어 오면서 Mobile Network에 PAN(Personal Area Network)과 유사한 형태의 Nested Mobile Network에 대한 관심이 높아지고 있으며, 이러한 Nested Mobile Network에서의 경로최적화(Route Optimization : RO) 기술에 대한 연구가 활발하게 진행되고 있다. NEMO(NEtwork MObility)의 RO를 위해 제안된 논문 중에 ORC(Optimized Route Cache Protocol)에 대한 제안이 있었다.[1] NEMO Basic Support가 표준안으로 채택되면서 연구 대상에서 거론되지 않고 있지만, 복잡한 이동성 기술인 Nested Mobile Network상의 RO를 위해 다시 검토해 볼 수 있을 것이다. 또한 동일 저자에 의해 제안된 Nested Mobile Network 내부에 Ad-hoc Routing 알고리즘인 OLSR(Optimized Link State Routing Protocol)을 적용한 제안이 발표되었다.[2] 본 논문에서는 ORC와 Nested Mobile Network상의 OLSR Scheme을 적용하여 RO를 위한 방안을 제안하고자 한다.

• Journal of the Korean Institute of Gas
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• v.19 no.2
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• pp.66-73
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• 2015

The amount and quality of waste heat from a gas engine which is modified from an automobile gasoline engine is analyzed. Exhaust temperature is $573.8^{\circ}C$ and engine cooling water exit temperature is $85.7^{\circ}C$. The amount of waste heat of engine cooling water is double compared to that of exhaust gas. Organic Rankine cycle (ORC) system is designed for two different waste heat source of engine cooling water and engine exhaust and is thermodynamically analyzed.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6353-6358
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• 2015

Background: To explore the safety, efficacy, and oncological outcome of 3-port laparoscopic radical cystectomy (LRC) compared to open radical cystectomy (ORC) in patients older than 75 years. Materials and Methods: From June 2010 to July 2014, we analyzed 16 radical cystectomies in patients older than 75 years (LRC group=8; ORC group=8). Demographic parameters, operative variables, and perioperative outcome in the 2 groups were retrospectively collected, analyzed, and compared. Results: Patients in both groups had comparable preoperative characteristics. A significantly longer operating time (476 vs. 303 min, P=0.0002) and less estimated blood loss (627 vs. 2,106 mL, P=0.021) were observed in the LRC group compared to the ORC group. Infection and ileus were the most common early complications after surgery. Patients who underwent ORC suffered from more postoperative infection (22.2% vs. 0.0%, P=0.054) and ileus (25.0% vs. 12.5%, P=0.521) than the LRC group, but the difference was not significant. Conclusions: Judging from this initial trial, 3-port LRC can be safely carried out in elderly patients. We suggest 3-port LRC as the primary intervention to treat muscle-invasive or high-risk nonmuscle-invasive bladder cancer in elderly patients with an otherwise relatively long life expectancy.

• Animal cells and systems
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• v.11 no.2
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• pp.129-134
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• 2007

The initiation of eukaryotic DNA replication requires assembly of the pre-replicative complex (Pre-RC) through the concerted action of Orc, Cdc6, Cdt1 and Mcm2-7 complex during G1 phase. The pre-RC assembly licenses individual replication origins for the initiation of DNA replication and sufficient number of the pre-RC is essential for proper progression of S phase. However, it is not well known how cells recognize the completion of the pre-RC assembly before G1-S transition. In order to understand the cellular responses to the defects in pre-RC assembly, we depleted the known components of pre-RC proteins using the small interference RNAs in HeLa cells. Although the defects of pre-RC assembly by the depletion of the pre-RC proteins such as Orc2, Cdt1, Mcm2 & Mcm10 did not elicit the activation of Chk1- or Chk2-dependent checkpoint pathways, these cells still showed significant decrease in the cellular level of Cdc25A proteins. These results suggests that a novel checkpoint pathway exist in HeLa cells, which is not dependent upon Chk1 or Chk2 proteins and play essential roles in the cellular responses to the defects in the pre-RC assembly. Also, among those four proteins tested in this study, the depletion of Mcm10 and Cdt1 proteins significantly increased the apoptotic cell death in HeLa cells, suggesting that these proteins not only play roles in the pre-RC assembly, but also are involved in the checkpoint responses to the defects in the pre-RC assembly.