• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.183.1-183.1
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• 2010

Recently, the increased interest in environmental issues has led to extensive research for development of green energy generation systems. However, only one type of generation system may not be sufficient for stand-alone mode because it cannot cope with the irregularity of weather condition. A hybrid generation system is able to make up for the weakness of each system. In this paper, a stand-alone hybrid wind/PV system is developed that can guarantee the stable energy supply. The system is suitable for power supply under 50W, and a vertical savonius type of blade was designed and applied for the wind generation system.

• Journal of Forest and Environmental Science
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• v.29 no.2
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• pp.125-130
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• 2013

An attempt was made on pulp production from the fast growing plant, Acacia hybrid to determine the total yield, screened yield, Kappa number, and fibre morphology of organosolv Acacia hybrid pulp. Uniform-sized chips were taken to undergo pulping in a digester with five different concentrations of ethanol, 50%, 60%, 70%, 80% and 90% (v/v) with 1 M of sodium hydroxide as catalyst. All chips were digested in a temperature-controlled digester with constant amount of water added and temperature of $185^{\circ}C$ with the duration of three hours cooking time and correspond pressure 1.1-1.2 MPa. It was observed that increasing of ethanol concentration has led to pulp yield increment and decreased in the degree of delignification at the same time. This study was aimed to focus on the effect of the varied concentration of organic solvent towards the pulp yield and its relationship with Kappa number and pulp yield.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1394-1402
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• 2011

This paper describes solar light collecting system which employs parabolic reflector and Fresnel lens and its industrial application. We have introduced second-stage optical system so that it makes optical fiber overcome its numerical aperture limitation and also it makes focused light become collimated, which results in decreased light energy density. As result of these, light collecting efficiency become maximized and the system does not require separate cooling apparatus any more. The developed solar lighting system together with artificial light source like LED has been applied to plant factory as a hybrid lighting source. This makes us save electric energy for artificial lighting during day time. The intensity of LED light in the hybrid lighting system is controlled automatically according to ambient-light-sensor installed in the system so that the light intensity for a plant always keeps the same level no matter how the sun light changes. For a plant factory whose size is 330 square meters, when solar lighting system is applied, 28,080KWh electric energy can be saved per month.2 times.

• Design & Manufacturing
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• v.10 no.3
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• pp.14-19
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• 2016

Thermally or electrically conductive filler reinforced polymer composites are extensively being developed as the demand for light weight material increases rapidly in industiral applications need good conductivity such as heat sink of the electronics or light. Carbon or ceramic materials like graphite, carbon nanotube or boron nitride are typical conductive fillers with good thermal or electical conductivity. Using these conductive fillers, the polymer composites in the market show wide range of thermal conductivity from approximately 1 W/mK to 20 W/mK, which is quite enhanced considering the thermal conductivity lower than 0.5 W/mK for most polymeric materials. The practical use of these composites, however, is yet limited to specific applications because most composites are still not conductive enough or too difficult to process, too brittle, too expensive for higher conductivity. For practical use of conductive composite, the thermal conductivity required depending on the heat releasing mode are studied first for simplified unit cooling geometry to propose thermal conductivities of the composites for reasonable cooling performance comparing with the metal heat sink as a reference. Also, as a practical design for heat sink based on polymer composite, composite and metal sheet hybrid structures are investigated for LED lamp heat sink and audio amplication module housing to find that this hybrid structure can be a good solution considering all of the cooling performance, manufacturing, mechanical performance, cost and weight.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.207-217
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• 2010

Recently, the use of DC power increased due to the increased use of digital load. Power factor of input current decrease and input current harmonics increase, and conversion loss which is occurred in the AC / DC converter is a problem to provide the proper DC voltage to the device equipped with an internal AC / DC converter. Hybrid system supplies the AC power and DC power to AC load (motor load and the transformer load) and DC loads (computers, TV, LED fluorescent light) at the same time it supplies the renewable energy and utility energy taken power from Utility to user for improving the efficiency and renewable energy improvements in ease of use. This paper studies DC characteristics of traditional AC load for Hybrid distributions.

• Journal of Sensor Science and Technology
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• v.33 no.5
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• pp.359-365
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• 2024

Chemiresistive semiconductor metal oxide (SMO) gas sensors detect gases based on resistance changes caused by gas adsorption/desorption on SMOs. These sensors have witnessed significant advancements with the development of microelectromechanical systems (MEMS) and nanotechnology. MEMS technology has facilitated mass production, miniaturization, and uniformity across sensors. Whereas, nanotechnology has contributed to the development of high-sensitivity gas sensing materials with large surface areas, catalytic coatings, and hybrid SMO junctions. However, SMOs require activation via external energy to overcome their bandgap energy and generate hot electron carriers, which are essential for high sensitivity and fast response/recovery times. Traditionally, embedded heaters have been used for this purpose; however, micro-and nano-heaters are plagued by high power consumption and low durability, which limit their use in mobile applications. Consequently, photoactivated gas sensing using light sources (e.g., lamps and LEDs) has garnered attention as an alternative approach. This study reviewed the progress from early lamp and LED-based research to recent studies on monolithic micro-LED (µLED) based gas sensors. µLED gas sensors facilitate room-temperature operation and ultra-low power consumption within the microwatt range. Consequently, they are highly suitable for integration into consumer electronics, smart farms, smart factories, and mobile gas sensors.

• Journal of Welding and Joining
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• v.32 no.5
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• pp.7-12
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• 2014

In this study, API-X100 steel pipes were welded with various kinds of welding wires in the laser-arc hybrid welding process. 10kW fiber laser source was combined to MIG arc welding process. API X-100 steel of base metal was of 16.9mm thickness, and butt welding applied. After welding, full penetration weld was acquired by 1-pass welding. A root porosity and the lack of fusion was observed in some welding conditions. By the mixing the melted wire, acicular ferrite, polygonal ferrite, pro-eutectoid, aligned side plate, and bainite structures were observed at the weld metal. From the observation of hybrid weld, unmixed zone had more Ni and Cr. The unmixed zone was a 1/3 area of the weld metal. As the mechanical test of the hybrid welding, tensile test and impact test applied. From the tensile test, all of the welding except SM70S was fractured at the base metal. The result of the impact test at -30 degree C led 60J~320J of the absorbed energy. The result of the low-absorbed energy might be from the coarse equiaxed structures of the weld metal.

• Advances in concrete construction
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• v.9 no.4
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• pp.375-386
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• 2020

In the present study, the effect of basalt, glass, and hybrid glass-basalt fibers on mechanical properties and fracture behavior of self-compacting concrete (SCC) mixes have been assessed at room and elevated temperatures. To do so, twelve mix compositions have been prepared such that the proper workability, flowability, and passing ability have been achieved. Besides, to make comparison possible, water to binder ratio and the amount of solid contents were kept constant. Four fiber dosages of 0.5, 1, 1.5, and 2% (by concrete volume) were considered for monotype fiber reinforced mixes, while the total amount of fiber were kept 1% for hybrid fiber reinforced mixes. Three different portions of glass and basalt fiber were considered for hybridization of fibers to show the best cocktail for hybrid basalt-glass fiber. Test results indicated that the fracture energy of mix is highly dependent on both fiber dosage and temperature. Moreover, the hybrid fiber reinforced mixes showed the highest fracture energies in comparison with monotype fiber reinforced specimens with 1% fiber volume fraction. In general, hybridization has played a leading role in the improvement of mechanical properties and fracture behavior of mixes, while compared to monotype fiber reinforced specimens, hybridization has led to lower amounts of compressive strength.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.3
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• pp.151-155
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• 2014

We have developed quantum dot light emitting diodes (QD-LEDs) using a InP/ZnSe/ZnS multi-shell QD emission layer. The hybrid structure of organic hole transport layer/QD/organic electron transport layer was used for fabricating QD-LEDs. Poly(4-butylphenyl-diphenyl-amine) (poly-TPD) and tris[2,4,6-trimethyl-3-(pyridin-3-yl)phenyl]borane (3TPYMB) molecules were used as hole-transporting and electron-transporting layers, respectively. The emission, current efficiency, and driving characteristics of QD-LEDs with 50, 65 nm thick 3TPYMB layers were investigated. The QD-LED with a 50 nm thick 3TPYMB layer exhibited a maximum current efficiency of 1.3 cd/A.

• Journal of the Korean Professional Engineers Association
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• v.44 no.2
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• pp.39-42
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• 2011

The main concern at the moment is securing rare earth(RE) resources, because the RE is the essential elements in green technology such as hybrid car, wind power plant, LED, display etc. It's impossible Korea will be a advanced country without securing RE. The importance of investment radically in the securing RE resources and professional engineers can not be overinvested.