• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.11
• /
• pp.57-68
• /
• 2013

The market for distributed power generation based on renewable energy is increasing, particularly for standalone mini-grid applications in developing countries with limited energy resources. Stand-alone power systems (SAPS) are of special interest combined with renewable energy design in areas not connected to the electric grid. Traditionally, such systems have been powered by diesel engine generator sets (DEGS), but also hybrid systems with photovoltaic and/or wind energy conversion systems (WECS) are becoming quite common nowadays. Hybrid energy systems can now be used to generate energy consumed in remote areas and stand-alone microgrids. This paper describes the design, simulation and feasibility study of a hybrid energy system for a stand-alone power system. A simulated model is developed to investigate the design and performance of stand-alone hydrogen renewable energy systems. The analysis presented here is based on transient system simulation program (TRNSYS) with realistic ventilation load of a large store. Design of a hybrid energy system is site specific and depends on the resources available and the load demand.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.8
• /
• pp.120-129
• /
• 1998

In this paper represented uninterruptible power sypply(UPS) equipment maintaining constant output voltage, using a pulse width modulation(PWM) voltage fed inverter, as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to DC side with solar cell using a Photovoltaic (PV) that it was so called constant voltage charge. In addition, better output waveform was generated because of PWM(pulse width Modulation) method, and it was Proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

• Nuclear Engineering and Technology
• /
• v.33 no.5
• /
• pp.468-482
• /
• 2001

As a process of Direct Containment Heating (DCH) issue resolution for Korean Standard Nuclear Power Plants (KSNPs), a containment load/strength assessment with two different approaches, the probabilistic and the deterministic, was performed with all plant-specific and phenomena-specific data. In case of the probabilistic approach, the framework developed to support the Zion DCH study, Two-Cell Equilibrium (TCE) coupled with Latin Hypercubic Sampling (LHS), provided a very efficient tool to resolve DCH issue. In case of the deterministic approach, the evaluation methodology using the sophisticated mechanistic computer code, CONTAIN 2.0 was developed, based on findings from DCH-related experiments or analyses. For three bounding scenarios designated as Scenarios V, Va, and VI, the calculation results of TCE/LHS and CONTAIN 2.0 with the conservatism or typical estimation for uncertain parameters, showed that the containment failure resulted from DCH loads was not likely to occur. To verify that these two approaches might be conservative , the containment loads resulting from typical high-pressure accident scenarios (SBO and SBLOCA) for KSNPs were also predicted. The CONTAIN 2.0 calculations with boundary and initial conditions from the MAAP4 predictions, including the sensitivity calculations for DCH phenomenological parameters, have confirmed that the predicted containment pressure and temperature were much below those from these two approaches, and, therefore, DCH issue for KSNPS might be not a problem.

• Journal of Sensor Science and Technology
• /
• v.27 no.4
• /
• pp.242-248
• /
• 2018

Bicycle fittings have been used to ride bicycles comfortably while minimizing non-traumatic injuries. To analyze the cause of non-traumatic injuries, it is necessary to measure the body weight distribution in various biking positions. In this study, a weight distribution measurement system was implemented by installing five weighable devices on the saddle, both pedals, and both handle grips of a bicycle. To measure the body weight applied through the saddle, the structure of a commercial seat post was modified and a load cell was installed inside. Weighable pedals and handle grips were designed using a 3D modeling program and fabricated by employing a 3D printer. The body weight distribution for ten bicycle riders was measured when the two pedals were aligned horizontally and vertically. Experimental results showed that the body weight distribution varied significantly depending on human body shape, even after the bicycle fitting was completed. The difference between the body weight measured by the proposed system and a commercial scale was less than 3 %.

• Journal of Korean Institute of Industrial Engineers
• /
• v.37 no.4
• /
• pp.289-296
• /
• 2011

In most distribution centers, products are received from the suppliers in units of pallet, stored in a rack, moved to the picking area for replenishment, picked according to customer orders, and shipped to customers. In some distribution centers, however, replenishment is made in not a whole pallet but only a portion of a pallet load, mainly due to the limited space in the order-picking area; as a result, partially loaded pallets occupy cells in the rack. As the number of slow-moving items increases, more cells are occupied by partially loaded pallets so that fewer empty cells are available for storing full, incoming pallets. This will necessitate the construction or leasing of additional storage space, which will entail significant cost. As an alternative, we propose pallet consolidation, which involves moving a partial load to another partially-loaded pallet in order to create one empty cell in the rack. In this paper, we define three pallet consolidation problems; formulate each problem as a binary integer programming model; and present heuristic algorithms for the problems. The average performance of each of the proposed heuristics is evaluated using simulation.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.8 no.4
• /
• pp.97-103
• /
• 2009

Since a demand for an extensive range of earthmoving equipment like a hydraulic excavator with a capacity of 85tons has been asked in construction fields, a performance of its track drive unit has to be verified experimentally. Among the verification of the performances, a torque measurement is at issue, in which a torque meter is utilized widely. However, the very large scaled torque meter is necessary when a discharged torque from the track drive unit is increased significantly. In addition, the price for experimental set-up of a torque meter is too high due to its limitation of the geometry such as long length, and a break down in operation occurs frequently. In this study, to measure a high torque up to 200,000Nm, a new technique was proposed as an alternative of conventional measurement by using a torque meter. The new technique enables to measure the high torque stably in a compact space via a torque arm and two load cells. The experimental results showed a propriety of the proposed torque measuring technique for a track drive unit with very large capacity.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.92.1-92.1
• /
• 2011

Anode off-gas of high temperature fuel cells such as MCFC contains a significant amount of combustible components like hydrogen, carbon monoxide and methane according to fuel utilization ratio of the fuel cell stack. Thus, it is important to fully burn anode off-gas and utilize the generated heat in order to increase system efficiency and reduce emissions as well. In the present study, 25 kW catalytic combustor has been developed for the application to a load-following 300kW MCFC system. Mixing and combustion characteristics have been experimentally investigated with the catalytic combustor. Since the performance of catalytic combustor directly depends on the combustion catalyst, this study has been focused on the experimental investigation on the combustion characteristics of multiple catalysts having different structures and compositions. Results show that the exhaust emissions are highly dependent on the catalyst loading and the ratio of catalytic components. Test results at load-following conditions are also shown in the present study.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.3
• /
• pp.73-81
• /
• 2006

In order to evaluate the thrust of a propulsion system, generally the captive thrust stand is used Based on the applied propulsion system, the various captive ways between thrust stand and the propulsion system are considered. In this paper, the effect of motor deformation generated during firing in horizontal thrust stand on the measured thrust is theoretically derived from classical beam theory. New flexure performance index is defined and estimated on the basis of the thrust measurement error. Its result is good agreement with numerical result of ABAQUS. This study showed that measurement reliability and safety of test can be highly upgraded, in case of two flexure-type captive thrust stand.

• Structural Engineering and Mechanics
• /
• v.21 no.3
• /
• pp.275-293
• /
• 2005

When a thin-walled multicell box girder is subjected to an eccentric load, the distortion becomes an important global response in addition to flexure and torsion. The three global responses appear in a combined form when a conventional shell element is used thus it is not an easy task to examine the three global responses separately. This study is to propose an analysis method using conventional shell element in which the three global responses can be separately decomposed. The force decomposition method which was designed for a single-cell box girder by Nakai and Yoo is expanded herein to multicell box girders. The eccentric load is decomposed in the expanded method into flexural, torsional, and multimode distortional forces by using the force equilibrium. From the force decomposition, the combined global responses of multicell box girders can be resolved into separate responses and the distortional response which is of primary concern herein can be obtained separately. It is shown from a series of extensive comparative studies using three box girder bridge models that the expanded method produces accurate decomposed results. Noting that the separate consideration of individual global response is of paramount importance for optimized multicell box girder design, it can be said that the proposed expanded method is extremely useful for practicing engineers.

• 한국태양에너지학회:학술대회논문집
• /
• 2011.04a
• /
• pp.25-30
• /
• 2011

In this paper, we analyzed the electrical characteristics with Micro-cracks in Photovoltaic module. Micro cracks are increasing the breakage risk over the whole value chine from the wafer to the finished module, because the wafer or cell is exposed to mechanical stress. And The solar cells have to with stand the stress under out door operation in the finished module. Here the mechanical stress is induced by temperature changes and mechanical loads from wind and snow. So, we experimentally analyze the direct impact of micro-cracks on the module power and the consequences after artificial aging. The first step, we made micro-cracks in PV module by mechanical load test according to IEC 61215. Next, PV modules applied the thermal cycling test, because micro-cracks accelerated aging by thermal cycling test, according to IEC61215. Before every test, we checked output and EL image of PV module. As the result of first step, we detected little power loss(0.9%). But after thermal cycling test increased power loss about 3.2%.