• Journal of the Korean Institute of Gas
• /
• v.2 no.4
• /
• pp.60-66
• /
• 1998

The hot stove system is a process that is continuously and constantly generating the hot combustion air required for the blast furnace. The hot stove process is considered as a main energy consumption process because it consumes about $20\%$ of the total energy in steel making works. So, many researchers have interested in the improvement of the heat efficiency of the hot stove to reduce the energy consumption. But they have difficulties in improving the heat efficiency of the hot stove because there is no precise information on heat transformation occurring during the heating period. In order to model the relationship between the operating conditions and heat efficiencies, we propose a neural network using feature extraction as one of experimental modeling methods. In order to show the performance of the model, we compare it with Partial Least Square (PLS) method. Both methods have similarities in using the dimension reduction technique. And then we present the simulation results on the prediction of the heat efficiency of the hot stove.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.3
• /
• pp.970-981
• /
• 1991

본 연구에서는 총괄 열 흡수율법과 분할법이 지니고 있는 전열 해석상의 한계 를 보완하고 슬래브 가열로의 전열해석에 실질적으로 적용하기 위하여, 분할법으로 내 내 분위기 온도를 계산하고 이로부터 슬래브의 노내 온도이력을 예측하는 계산모델을 제시하였다. 계산모델의 유용성 확인을 위하여는, Fig.1에 보인 바와 같은 최대 슬 래브 처리량이 235ton/hr인 후판 가열로를 대상으로 하여, 노내 분위기 가스 온도 및 슬래브의 온도이력을 측정하고 이를 계산 결과와 비교하였다. 이와 아울러 연료유량, 슬래브 재로시간(residence time) 및 장입 온도등의 조업조건 변화가 분위기 가스온도 와 슬래브의 온도이력에 미치는 영향을 검토하여 가열로의 효율적 조업을 위한 자료를 제시하였다.

• Korean Chemical Engineering Research
• /
• v.49 no.4
• /
• pp.423-431
• /
• 2011

Recentincreasing awareness of the environmental damage caused by the $CO_2$ emission of fossil fuelsstimulated the interest in alternative and renewable sources of energy. Fuel cell is a representative example of hydrogen energy utilization. In this study, Molten Carbonate Fuel Cell system is simulated by using $Aspen^{TM}$. Stack model is consisted of equilibrium reaction equations using $ACM^{TM}$(Aspen Custom Modeler). Balance of process of fuel cell system is developed in Aspen $Plus^{TM}$ and simulated at steady-state. Analysis of performance of the system is carried out by using sensitivity analysis tool with main operating parameters such as current density, S/C ratio, and fuel utilization and recycle ratio.In Aspen $Dynamics^{TM}$, dynamics of MCFC system is simulated with PID control loops. From the simulation, we proposed operation range which generated maximum power and efficiency in MCFC power plant.

• Journal of Energy Engineering
• /
• v.29 no.2
• /
• pp.1-9
• /
• 2020

In recent days, fuel cell has received attention from the world as an alternative power source to hydrocarbon used in automobile engines. With the industrial advances of fuel cell, There have been a lot of researches actively conducted to find a way of generating hydrogen. Among many hydrogen production methods, Solid Oxide Electrolysis Cell(SOEC) is not only a basic way but also environment-friendly method to produce hydrogen gas. Solid Oxide Electrolysis Cell has lower electrical energy demands and high thermal efficiency since it is possible to operate under high temperature and high pressure conditions. For these reasons, experimental researches as well as studies on numerical modeling for Solid Oxide Electrolysis Cell have been under way. However, studies on numerical modeling are relatively less enough than experimental accomplishments and have limited performance prediction, which mostly is considered as a result from inadequate effects of electrochemical properties by temperature and pressure. In this study, various experimental studies of commercial Membrane Electrode Assembly (MEA) composed of Ni-YSZ (40wt%, Ni-60 wt% YSZ)/8-YSZ (TOSOH, TZ8Y)/LSM (La_0.9Sr_0.1MnO₃) was utilized for improving effectiveness of SOEC model. After numerically analyzing effects of electrochemical properties according to operating temperature, causing the largest deviation between experiments and simulation are that Charge Transfer Coefficient (CTC), exchange current density, diffusion coefficient, electrical conductivity in SOEC. Analyzing temperature effect on parameter used in overpotential model is conducted for modeling of SOEC. cross-validation method is adopted for application of various MEA and evaluating feasibility of model. As a result, the study confirm that the numerical model of SOEC based on structured process of effectiveness evaluation makes performance prediction better.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.672-682
• /
• 2020

The Korea Nowadays, which is research on digital twin technology for efficient operation in various industrial/manufacturing sites, is being actively conducted, and gradual depletion of fossil fuels and environmental pollution issues require new renewable/eco-friendly power generation methods, such as wave power plants. In wave power generation, however, which generates electricity from the energy of waves, it is very important to understand and predict the amount of power generation and operational efficiency factors, such as breakdown, because these are closely related by wave energy with high variability. Therefore, it is necessary to derive a meaningful correlation between highly volatile data, such as wave height data and sensor data in an oscillating water column (OWC) chamber. Secondly, the methodological study, which can predict the desired information, should be conducted by learning the prediction situation with the extracted data based on the derived correlation. This study designed a workflow-based training model using a machine learning framework to predict the pressure of the OWC. In addition, the validity of the pressure prediction analysis was verified through a verification and evaluation dataset using an IoT sensor data to enable smart operation and maintenance with the digital twin of the wave generation system.

• Journal of Aerospace System Engineering
• /
• v.13 no.5
• /
• pp.39-48
• /
• 2019

The turbulent flow in the rotor-stator mixer is based on shear characteristics generated by the interaction of the stator with the rotor rotating at high speed. In this study, the flow characteristics analysis of the unsteady state generated by the interaction of the rotor and the stator in the prototype model of the emulsion-fuel related mixer development was performed with the MRF and SMM by applying the ANSYS FLUENT $k-{\varepsilon}$ (RKE) turbulence model. The behavior and shear characteristics of the flow particles generated at the interface between the designed rotor and stator, and trends such as velocity distribution and turbulence eddy dissipation, were predicted and verified using the CFD analysis.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.396-396
• /
• 2023

기후 위기에 대한 대응으로 현재 많은 국가에서 2050년 탄소중립을 목표로 하고 있으며, 우리나라도 2050년까지 탄소중립을 선언하고 다양한 부문의 배출 절감 계획을 내세웠다. 현재 건물 부문에서는 2050년의 목표배출량을 6.2 백만톤 CO2eq으로 설정하고 관련 정책적 수단을 검토 중이지만 달성 방안 등에 대해서는 구체적으로 제시하지 못하고 있다. 본 연구에서는 국내 건물 부문의 이산화탄소의 배출량 산정 모델을 개발하여, 2050년까지 이산화탄소 배출 저감 시나리오를 시뮬레이션하였다. 이를 토대로 국내의 건물 부문 탄소중립 가능성을 검토한 통합 시나리오를 제시하고, 향후 정책 및 기술 개발의 방향성을 제시한다. 탄소배출량 산정모델은 연면적 예측 및 사용 에너지의 원단위 환산, 탄소배출계수 등을 고려해 개발하였고, 이를 활용하여 4가지 탄소배출 시나리오를 분석하였다. 먼저 현재 정책 기반 탄소 배출 시나리오는 탄소중립에 이르지 못하여 더 강화된 시나리오의 필요성을 보여준다. 신규 건물을 대상으로 한 제로 에너지화 제도 기반 시나리오는 전체 탄소배출량에 큰 기여를 하지 못하며, 기존 건물 대상의 그린 리모델링 제도 기반 시나리오에서는 10년 이상 건물에 50% 이상의 높은 에너지 효율 개선을 시행해야 한다는 결과를 도출하였다. 또한 전기화 시나리오에서는 화석연료와 전력의 탄소배출계수를 비교하여 적절한 에너지 전환 시점을 계산하였다. 그 결과, 건물 부문에서 2050년까지 탄소배출량 감축 목표 달성을 위해 신축 건물의 에너지 자립율 100%, 에너지 전환 계획과 연동한 건물의 전기화, 그리고 그린리모델링을 통한 효율 개선 기준을 47% 이상 달성하는 조건을 만족해야 한다는 결과를 얻었다. 이 연구는 도전적인 온실가스 감축 마련의 필요성을 제시하였으며, 탄소중립 가능성을 제시하여 실질적인 감축정책에 기여할 것으로 기대한다.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1670_1671
• /
• 2009

산업경제구조의 변화로 경험이 풍부한 전문가들이 은퇴하고 경험이 적은 직원들이 그들의 업무를 대신하는 구조로 조직이 변화하고 있다. 동시에 녹색성장시대의 도래로 화석연료를 사용하는 설비에 대한 투자가 줄면서 점차로 노후화되는 경향을 보이고 있어 불필요한 운전 과도현상에서 기인된 극단적인 손상은 설비자체 및 전력공급계통 전체에 치명적이라고 할 수 있다. 따라서 석탄화력발전소 제어 시스템은 이러한 사안들을 안정적으로 이끌어 나가기 위한 중요한 요소로 저비용 고효율 발전소 유지를 위해 중점적으로 발전시켜 나가야 할 부분이다. 본 논문은 석탄화력발전소의 주구성요소인 보일러와 터빈을 제어하는 마스터 제어기의 복잡한 로직을 모델 기반의 간단한 로직으로 개발하여 시뮬레이션 한 결과를 실제 발전소에 적용하기 위한 내용을 기술하였다. 실제 발전소는 많은 위험요소들을 안고 있기 때문에 시뮬레이션에서 나타나는 급격한 제어동작을 수용할 수 없을 경우도 있으며, 실제 다른 많은 변수들이 제어불안정 요소로 작용할 수 있다. 차후 실제 적용한 결과는 예측제어의 사용과 같은 제어시스템 향상을 위한 개발과 운영효율 향상에 사용될 것이다. 튜닝 과정에서의 연구결과는 시간절약과 제어부분 결함제거 등 직원들의 전문지식 향상 등에 도움을 주게 될 것이다.

• Journal of Korean Society for Atmospheric Environment
• /
• v.33 no.3
• /
• pp.191-204
• /
• 2017

Concerns on the air pollution problem caused by ambient fine particles have become a big social issue in Korea. Important factors that should be addressed to develop effective and efficient air quality management policy, especially, against fine particles are discussed and research and policy directions to address these factors are suggested. It is suggested that two factors are in high priority; one is scientific understanding of the major formation mechanisms of fine particles and the other is the process of policy decision and implementation. For the scientific understanding, smog chamber measurement, intensive field study, and chemical transport model development that can simulate the characteristics of Northeast Asia are considered to be important. For the policy directions, priority setting of the proposed policies and development and implement of effective communication sytem are considered to be important.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.2
• /
• pp.187-192
• /
• 2019

Hybrid power storage system with emergency power function for demand management and power outage minimizes the investment cost in the building of buildings and factories requiring emergency power generation facilities, We propose a new business model by developing technology that can secure economical efficiency by reducing power cost at all times. Normally, system power is supplied to load through STS (Static Transfer Switch), and PCS is connected to system in parallel to perform demand management. In order to efficiently operate the electric power through demand forecasting, the EMS issues a charge / discharge command to the ESS as a PMS (Power Management System), and the PMS transmits the command to the PCS controller to operate the system. During the power outage, the STS is rapidly disengaged from the system, and the PCS becomes an independent power supply and can supply constant voltage / constant frequency power to the load side. Therefore, it is possible to secure reliability through verification of actual system linkage and independent operation performance of hybrid ESS, By enabling low-carbon green growth technology to operate in conjunction with an efficient grid, it is possible to improve irregular power quality and contribute to peak load by generating renewable energy through ESS linkage. In addition, the ESS is replacing the frequency follow-up reserve, which is currently under the charge of coal-fired power generation, and thus it is anticipated that the operation cost of the LNG generator with high fuel cost can be reduced.