• Proceedings of the IEEK Conference
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• summer
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• pp.325-329
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• 2004

Linear size expanders have been studied in many fields for the practical use, which is possibility to connect large numbers of device chips in parallel communication systems. One major limitation on the efficiency of parallel computer designs has been the prohibitively high cost of parallel communication between processors and memories. Linear size expanders can be used to construct theoretically optimal interconnection networks. In current, the defined constructions have large constant factors, thus rendering them impractical for reasonable sized networks. This paper presents an improvement on constructing concentrators using an $(n,\;k,\;2rs/(r^2-s^2))expander,$ which realizes the reduction of the size in a superconcentrator by a constant factor.

• Journal of Power System Engineering
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• v.17 no.2
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• pp.87-94
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• 2013

Applicability of organic Rankine cycle for a passenger car with 3.5 L gasoline engine to convert low grade waste heat to useful shaft power has been numerically studied. Working fluid is R134a, and the Rankine cycle is composed of boiler for recovering engine cooling water heat, super heater for recovering exhaust gas heat, scroll expander for converting waste heat to shaft power, condenser for heat emission, internal heat exchanger, and feed pump. Assuming efficiencies of 90% for the heat exchangers, 75% for the scroll expander, and 80% for the feed pump, the Rankine cycle efficiency of 5.53% was calculated at the vehicle speed of 120 km/hr. Net expander shaft output after subtracting the power required to run the pump was 3.22 kW, which was equivalent to 12.1% improvement in fuel consumption. About the same level of improvement in the fuel consumption was obtained over the vehicle speed range of 60 km/hr~120 km/hr.

• Journal of Drive and Control
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• v.12 no.4
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• pp.1-7
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• 2015

In this study, a spiral valve which is used with a cryogenic linear expander and composed of plural plate coil shapes was examined. Generally, a spiral valve is well known for having excellent efficiency and low noise characteristics. In order to determine the movement characteristics and to investigate the limit of valve displacement, the stress variations according to the changes of operating pressure, displacement and workable temperature are discussed. From this examination, it is considered that the results of this study will significantly facilitate the design and development of a spiral valve for the cryogenic linear expander.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.325-332
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• 2005

This paper addresses the development of a scroll expander for power generation from relatively low temperature steam source. It has a double-sided orbiting scroll member so that no thrust bearing is needed to support the base plate of the orbiting scroll. Three power transmission shafts are placed at the periphery of the orbiting scroll base plate, and these shafts can also function as anti-rotation devices. Final output is obtained from the main central shaft engaged with the three power transmission shafts through gear assembly. The clearance between the fixed and orbiting scroll elements was estimated by comparing measurement of the mass flow rate with calculation results of a computer simulation. Due to large clearance, the expander total and volumetric efficiencies were measured to be $34\%\;and\;43\%$, respectively. It has been shown through the computer simulation that the total and volumetric efficiencies could be improved to $65\%\;and\;83\%$, respectively, if the current clearance is reduced by half.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.12
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• pp.1721-1725
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• 2012

A growth and digestibility study was conducted using Osmanabadi goat male kids by feeding complete diets in the form of mash or expander extruded pellets containing different levels of red gram (Cajanus cajan) straw (RGS). Two iso-nitrogenous complete diets were prepared by incorporating RGS at 35% and 50% levels. Half the quantity of each complete mash feed was then converted into pellets through expander extruder processing. Thirty two kids of 4 to 5 months age were divided into four groups of eight each and were fed for 150 d with four experimental diets (T1: mash with 35% RGS, T2: mash with 50% RGS, T3: pellets with 35% RGS and T4: pellets with 50% RGS). Pelleting of complete diets significantly (p<0.001) increased the voluntary feed intake (671.45 vs 426.28 g/d) at both levels of RGS in the feeds. Average daily gain (ADG, g/d) also increased significantly (p<0.001) from 48.79 in kids fed mash diet to 71.29 in those fed with pelleted diets. Feed conversion efficiency (dry matter (DM) intake: weight gain) was comparable among all the treatment groups. Digestibility of nutrients was not affected by pelleting of the feeds whereas, increasing the level of inclusion of RGS in feeds from 35% to 50% decreased (p<0.05) the digestibility of DM and crude protein (CP) resulting in lower (p<0.001) metabolizable energy (ME) content (MJ/kg DM) in feeds with 50% RGS (7.93 vs 8.75). Daily intake (MJ/kg $BW^{-0.75}$) of ME decreased (p<0.05) in feeds containing 50% RGS while pelleting of feeds increased (p<0.05) the intake of DM, CP, digestible crude protein (DCP) and ME. It is inferred that expander extruder pelleting can efficiently utilize RGS up to 50% level in complete diets for growing goat kids.

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.179-187
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• 2005

Linear order Concentrators and Superconcentrators have been studied extensively for their ability to interconnect large numbers of devices in parallel, whether in communication systems or in parallel computers. One major limitation on the efficiency of parallel computer designs has been the prohibitively high cost of parallel communication between processors and memories. Linear order concentrators, O(n), can be used to construct theoretically optimal interconnection network schemes. Existing explicitly the defined constructions are based on expanders, which have large constant factors, thereby rendering them impractical lot reasonable sized networks. It demands the construction of concentrator which uses the expander with the smaller expansion constant. This paper introduces an improvement on the method of constructing concentrators using expanders, which reduce the size of resulting concentrator built from any given expander by a constant factor.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.2
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• pp.248-256
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• 2003

Two experiments were conducted to determine the effects of expander processing and enzyme supplementation of wheat-based diets on growth performance and nutrient digestibility in finishing pigs. For Exp. 1, 60 finishing pigs (average initial BW of 49.5 kg) were fed meal, standard pellets and expanded pellets in a 70 d growth assay. From 49.5 to 79.0 kg, 79.0 to 111.8 kg, and overall (49.5 to 111.8 kg), ADG and ADFI were not affected by pelleting or standard vs expander conditioning (p>0.22). However, from 49.5 to 79.0 kg, pigs fed pellets have greater gain/feed than pigs fed mash (p<0.04), and pigs fed expanded pellets tended to have greater (p<0.10) gain/feed than pigs fed standard pellets. Overall (i.e. from 49.5 to 111.8 kg), gain/feed (p<0.02) and apparent fecal digestibilities of DM (p<0.001) and N (p<0.02) were improved by pelleting the diets. Also, expander processing further improved gain/feed (p<0.06) and digestibility of DM (p<0.04) compared to standard steam conditioning. Scores for keratinization (p<0.002) and ulceration (p<0.003) of the stomach were increased by pelleting, but the mean scores for the various treatments ranged only from 0.05 to 1.08 (i.e., low to mild keratosis and ulceration). For Exp. 2, 80 pigs (average initial BW of 54.1 kg) were fed mash and pellets (standard or expander) without and with xylanase. The enzyme was added to supply 4,000 units of xylanase activity/kg of diet. Adding xylanase to the mash diet improved gain/feed from 90.7 to 115.9 kg (p<0.04) of the growth assay and digestibility of DM (p<0.05) on d 39. However, in pelleted diets, adding the enzyme did not improve growth performance or digestibility of nutrients. Pelleting tended to increase scores for ulceration (p<0.06), and enzyme supplementation decreased stomach keratinization scores for pigs fed the standard pellets (p<0.01). However, as in Exp. 1, the mean scores for all treatment groups were quiet low (i.e., ranging from normal to mild). In conclusion, pelleting improved efficiency of growth, but additional benefits from expander conditioning were observed only in Exp. 1. Finally, xylanase tended to improve growth performance and nutrient digestibility, only in pigs fed mash diets but not in pigs fed pellets.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.11
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• pp.1572-1576
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• 2003

A growth trial of 180 days was conducted on 18 crossbred calves (6-9 months, $73.48{\pm}6.52kg)$ by randomly allotting to two complete diets and a conventional diet (6 in each group). The complete diets were formulated containing 40 per cent cotton straw, one processed in mash form and other subjected to expander-extruder pelletization (EEP). These two complete diets were compared with conventional system of feeding under which concentrate mixture and cotton straw were fed separately in a 60:40 ratio. The calves on EEP complete diet consumed more (p<0.01) DM in comparison to other two groups. The DMI per 100 kg body weight was similar among all the diets. The ADG was significantly (p<0.01) higher in calves fed EEP complete diets (815.4 g) followed by mash (627.0 g) in comparison to conventional diet (464.9 g). The DM intake per kg metabolic body weight was higher (p<0.01) on complete diet than conventional diet. The intakes of DCP (p<0.05), TDN (p<0.01), and ME (p<0.01) per kg metabolic body weight were significantly higher on EEP complete diet in comparison to mash and conventional diet. The water intake per kg DM intake was comparable among all the diets. The efficiency of DM utilisation was higher p (<0.05) on EEP complete diet (5.84) in comparison to conventional diet (7.41), whereas on mash diet it was intermediate (6.68). The efficiency of DCP utilization was similar in mash and EEP complete diet fed groups, which was higher (p<0.05) than that of the conventional diet. Expander-extrusion though increased the cost of production it reduced the cost of feed per unit live weight gain by 12.28% in comparison to its mash form and by 16.76% when concentrate and cotton straw were fed separately. The results indicated that blending of cotton straw along with concentrates in a complete diet increased the palatability of the straw in comparison to conventional system and expander extruder processing of cotton straw based complete diet gave better growth performance and may form an economic ration for growing crossbred calves.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.919-926
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• 2013

Experiments were conducted to determine the operating characteristics of a small-scale ORC (organic Rankine cycle) system for various low-temperature heat sources. A small-scale ORC power generation system adopting R-245fa as a working fluid was designed and manufactured. Hot water was used as the heat source, and the temperature was controlled using 110-kW electric resistance heaters that provided temperatures of up to $150^{\circ}C$. An open-drive oil-free scroll expander directly connected to a synchronous generator was installed in the ORC unit. Experiments were conducted by varying the rotational speed of the expander under the same heat source temperature conditions. The factors that influence the performance of the small-scale ORC system were analyzed and discussed.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.299-305
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• 2016

The High Temperature Superconducting power cables (HTS power cables) become increasingly longer to commercialize the HTS power cable system. Accordingly, demands on refrigerators of large cooling capacity per a unit system have been increased. In Korea, it is currently imported from abroad with the high price due to insufficient domestic technologies. In order to commercialize the HTS power cables, it is necessary to develop the refrigerators with large cooling capacity. The Brayton refrigerators are composed of recuperative heat exchangers, compressors and cryogenic turbo expanders. The most directly considering the efficiency of the Brayton refrigerator, it depends on performance of the cryogenic turbo expander. Rotating at high speed in cryogenic temperature, the cryogenic turbo expanders lower temperature by expanding high pressure of a helium or neon gas. In this paper, the reverse Brayton cycle is designed and the cryogenic turbo expander is designed in accordance with the thermodynamic cycle.