• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.6
• /
• pp.716-724
• /
• 1999

In co-orbiting scroll compressor, the two scroll members are to orbit with independent radii, producing a relative orbit motion between them. One scroll member is driven by the crank mechanism while the motion of the other member is determined by geometrical constraints and reacting forces. This paper presents an analytical study on the performance of a co-orbiting scroll compressor. The following results have been obtained: Radial contact force between the scroll wraps is virtually free from the centrifugal force of the orbiting scroll member. The frictional losses are somewhat increased due to the complicated drive mechanism, yielding to a little lower EER compared to conventional radially compliant scroll compressors .

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.9 no.2
• /
• pp.93-103
• /
• 1997

This study presents a way of improving the stability of fixed scroll in scroll compressors. For the scroll compressor whose fixed scroll is designed to move in the axial direction for the axial compliance, the fixed scroll is under the influence of the overturning moment produced by internal gas forces. Unless the overturning moment is properly compensated by the moments of reaction forces at the suspension of the fixed scroll to the compressor frame, the fixed scroll would exhibit wobbling motion, increasing gas leakage through the gap induced by the wobbling of the fixed scroll between the two scroll members. The conditions on which the wobbling motion can be suppressed have been found analytically; The axial position of the fixed scroll suspension should be made within a certain range. The upper limit of this range is the axial location for the o-rings which are inserted between the fixed scroll and the back pressure chamber to promote sealing for the gas in the back pressure chamber. And the lower limit is mainly determined by the magnitude of the axial sealing force. As long as the axial sealing force is not negative over all crank angles, the lower limit is not above the mid-height of the scroll wrap. Larger axial sealing force lower the lower limit.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.30 no.4
• /
• pp.348-357
• /
• 2024

Maneuvering performance is crucial for fishing vessels, especially under operational conditions that involve frequent course changes and weight variations due to catch. Small vessel accidents account for approximately 60% of maritime incidents as of 2022, mainly attributed to collisions and stranding accidents due to insufficient maneuvering performance. Especially, accidents that occur on small vessels less than 10 tons account for about 65% of all accidents. The absence of international standards presents challenges in accurately evaluating the maneuvering performance of small vessels. In this study, a 4.99-ton small fishing vessel was selected as the target, and a 3d-cad model was created. The commercial numerical analysis program STAR-CCM+ was employed to establish a simulation environment for the vessel's maneuvring motion. Based on this standard loading conditions and weight distribution were considered, 10° / 10°, 20° / 20° zigzag tests and 35° turning test were conducted. The results revealed a tendency for decreased yaw and course-keeping performance and improved turning performance as the hull weight increased. However, in partial arrival and full load departure condition, the manoeuvering performance were relatively poor. Based on this, the need for evaluation of maneuvering and standardized criteria of maneuvering performance for safe navigation of small vessels is presented. Furthermore, it is expected that the evaluation results of maneuvering performance in this study can serve as fundamental data for establishing criteria for evaluating the maneuvering performance of small vessels.

• KOMUNHWA
• /
• no.60
• /
• pp.101-120
• /
• 2002

The floor tile on a coated green-glass was excavated from the Beobgwangsa Temple Site in the Pohang City. We analyzed using the MXRD, ICP-AES, EDXRF, TG/DTA and TIMS. As a result of microscope analysis, it was composed of quartz, feldspar and clay particl

• Journal of Food Hygiene and Safety
• /
• v.22 no.2
• /
• pp.82-87
• /
• 2007

This research was performed to investigate chemical and microbiological hazards of Ready-to-eat(RTE) compound foods which uses the by-product of meat. For this experiment, 51 samples of RTE compound foods in by-product of meat distributed in Incheon from January to December 2006 were tested. The contents of heavy metals in the main ingredient of RTE compound foods were in the range of $0.073{\sim}0.112ppm$ for lead (Pb), $0.006{\sim}0.013ppm$ for cadmium (Cd) and $0.746{\sim}0.978ppb$ for mercury (Hg). The concentrations of residual ABS(alkyl benzene sulfate) in the small intestine which is a main ingredient of Gopchang-casserole were $$0.8ppm{\sim}57.6ppm$ (Ave. 10.3ppm). Staphylococcus aureus was isolated from 11 samples (21.6%) among 51 main ingredients of RTE compound foods. The isolation rates of Salmonella spp. and Clostridium perfringens were 2.0% (1/51) and 5.9% (2/51), respectively. By types of main ingredient, the small intestine was showed the highest isolation rate as 35.3% (12/34), ham and the sausage which are main ingredients of the Budae-pot stew were 25% (2/8) and other meat products were 20% (1/5). Food poisoning bacteria was not found in the blood of pig which is a main ingredient of the Sunji-pot stew. 28.4% (27/95) of sauce included in each RTE compound foods were coliform bacteria positive. Pesticide residues were found in four of 45 vegetables which are the additional ingredient of RTE compound foods. The concentrations of pesticide were chlorothalonil 2.8 ppm, EPN 10.3 ppm, chlorpyrifos 0.4ppm and indoxacarb 0.7ppm. In 33 bean sprout samples, captan and carbendazim were not detected.