• 에너지공학
• /
• 제15권3호
• /
• pp.188-193
• /
• 2006

본 논문은 보일러 화로내 임의의 단면에서 다수의 음속 측정기를 설치하여 음속을 측정하고 평균온도, 최고온도, 최저온도로부터 세분화시킨 격자의 온도를 구하여 온도분포를 구현하는 방법에 대한 이론적 고찰과 적용결과에 관한 것이다. 음속 측정기 간 음속을 측정하여 보일러 내부의 연소가스 온도를 측정하고 화로를 임의의 격자로 구분하여 각 격자에 해당하는 온도값을 주위 격자의 온도구배로부터 유추하여 구한 뒤 모든 격자의 온도값을 완성하여 화로의 온도분포를 구현하는 방법에 대한 이론 및 관련 시스템을 구성하고 실제 현장적용하여 결과를 분석하였다.

• 신재생에너지
• /
• 제10권3호
• /
• pp.22-30
• /
• 2014

The isolated self-generating electricity with diesel engine generator has been used in islands far away from main land. It costs high because of increasing oil price, and unsafe to have supplying oil and its related components by ship due to unexpectable marine conditions. Therefore there is the need for the hybrid system of renewable energy like wind or solar energy systems with oil engine generator, which can reduce oil use and extend oil supplying period. In this study, the feasibility of such hybrid system with smart micro grid on the eight islands of Jeon-nam province is surveyed to find good place for the demonstration test of the hybrid system. In each island, 3 wind turbine systems of 10 kW and photovoltaic of 20 kW are tested with already installed diesel engine. The performance and costs of the hybrid system in each island are compared in the given conditions of solar and wind energy potential. As a result of the study, Jung-ma island is recommended for the optimum place to make real field demonstration test of isolated hybrid generating and smart grid systems.

• Journal of Electrical Engineering and Technology
• /
• 제12권6호
• /
• pp.2118-2126
• /
• 2017

The large-scale power system blackouts have indicated that conventional protection relays that based on local signals cannot fit for modern power grids with complicated setting or heavily loaded-flow transfer. In order to accurately detect various faulted lines and improve the fault-tolerance of wide-area protection, a novel multi-section weighed fault matching and detecting algorithm is proposed. The real protection vector (RPV) and expected section protection vectors (ESPVs) for five fault sections are constructed respectively. The function of multi-section weighed fault matching is established to calculate the section fault matching degrees between RPV and five ESPVs. Then the fault degree of protected line based on five section fault degrees can be obtained. Two fault detecting criterions are given to support the higher accuracy rate of detecting fault. With the enumerating method, the simulation tests illustrate the correctness and fault-tolerance of proposed algorithm. It can reach the target of 100% accuracy rate under 5 bits error of wide-area protections. The influence factors of fault-tolerance are analyzed, which include the choosing of wide-area protections, as well as the topological structures of power grid and fault threshold.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2016년도 춘계학술대회
• /
• pp.285-286
• /
• 2016

해상교통관제센터에 의해 실시간으로 수집되는 선박의 항해 데이터를 바탕으로 선박 항적 패턴 인식을 수행하고 이를 바탕으로 항적 모델을 추출하여 사전에 선위를 예측하는 기법을 제안한다. 항적 데이터의 처리와 가공, 항적 모델링을 위하여 Support Vector Regression 알고리즘이 사용되었으며, 적정 파라미터 선정을 위하여 k-fold cross validation과 grid search가 사용되었다. 제안된 항적 데이터 모델링 기법을 통하여 사전에 선박의 선위를 예측하여 해상교통과제사의 의사결정을 지원하고자 한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.484-485
• /
• 2011

Since the year 2008, the first demonstration project of the superconducting cable for the KEPCO grid operation has been in progress. To apply the HTS (High Temperature Superconducting) cable system into the commercial network, a new test complex was built in the 154kV Icheon substation and the on site assembly of 22.9kV, 50MVA HTS cable with the cryogenic refrigeration system was finished. A full scale of HTS cable fabricated with 2nd generation wire is to be in service in KEPCO network. In this paper, a series of processes of the installation and operation test are introduced.

• 로봇학회논문지
• /
• 제9권3호
• /
• pp.154-159
• /
• 2014

The Global Positioning System (GPS) is widely used to aid the navigation of aerial vehicles. However, the GPS cannot be used indoors, so alternative navigation methods are needed to be developed for micro aerial vehicles (MAVs) flying in GPS-denied environments. In this paper, a real-time three-dimensional (3-D) indoor navigation system and closed-loop control of a quad-rotor aerial vehicle equipped with an inertial measurement unit (IMU) and a low-cost light detection and ranging (LIDAR) is presented. In order to estimate the pose of the vehicle equipped with the two-dimensional LIDAR, an octree-based grid map and Monte-Carlo Localization (MCL) are adopted. The navigation results using the MCL are then evaluated by making a comparison with a motion capture system. Finally, the results are used for closed-loop control in order to validate its positioning accuracy during procedures for stable hovering and waypoint-following.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
• /
• pp.525-526
• /
• 2006

Recently, much research has been done and many improvements have been developed for islanding protection of distributed generation(DG). Anti-islanding protection for DG must be act very quickly to prevent equipment damage at the time of disconnection and for the safety of maintenance and repair personnel. DG-based detection methods have included both passive and active types, and now research has shifted towards new anti-islanding detection methods that make up for the defects of the previous types. Because differences occur between the utility grid and the DG when connecting and disconnecting depending on the phase difference, voltage, current, relative capacity of electric power, and system operation characteristics, voltage phase angle is an important consideration. In this paper, we simulated islanded operation characteristics comparing phase difference of DG and the connected utility grid, and analyzed various parameters (real power, reactive power, RMS voltage, RMS current, power factor angle, and frequency) by varying the DG's voltage phase angle. Using this information, we propose a suitable DG voltage phase angle for enhanced passive islanding detection techniques.

• Journal of Mechanical Science and Technology
• /
• 제19권9호
• /
• pp.1773-1780
• /
• 2005

The process of mould design in the foundry industry has been based on the intuition and experience of foundry engineers and designers. To bring the industry to a more scientific basis the design process should be integrated with scientific analysis such as heat transfer. The production by foundry techniques is influenced by the geometry configuration, which affects the solidification conditions and subsequent cooling. Numerical simulation and/or experiments make possible the selection of adequate materials, reducing cycle times and minimizing production costs. The main propose of this work is to study the heat transfer phenomena in the mould considering the phase change of the cast-part. Due to complex geometry of the mould, a block unstructured grid and a generalized curvilinear formulation engaged with the finite volume method is described and applied. Two types of boundary conditions, diffusive and Newtonian, are used and compared. The developed numerical code is tested in real case and the main results are compared with experimental data. The results showed that the solidification time is about 6 seconds for diffusive boundary conditions and 14.8 seconds for Newtonian boundary conditions. The use of the block unstructured grid in combination with a generalized curvilinear formulation works well with the finite volume method and allows the development of more efficient algorithms with better capacity to describe the part contours through a lesser number of elements.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
• /
• pp.182-187
• /
• 2012

Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. Therefore, output current sensor measures sensing value that includes offset again. In this paper we propose new algorithm where two identical forward and reverse sensors are used to calculate the offset in real time. As a result the offset is not correlated with temperature change. The proposed algorithm is verified through PSIM simulation for validity.

• 한국태양에너지학회 논문집
• /
• 제34권4호
• /
• pp.67-74
• /
• 2014

The fluctuation of the output power of wind farms will be able to cause the impact on the Jeju power system such as power quality and stability. To settle the matter, many researchers have proposed the use of the BESS(Battery Energy Storage System) in the wind farm. In this paper, The BESS is applied to each wind farms for mitigating the fluctuation of wind power output. The BESS is controlled for smoothing the output of wind farms. Two kinds of simulation will be carried out. First, the simulation results by using PSCAD/EMTDC simulation program are compared to the measured data from the real power grid in Jeju Island. The other is to analyze the output of wind farms when the BESS is applied to the simulation works. The simulation results will demonstrate the effectiveness of using BESS to stabilize for power grid in Jeju Island.