• The KSFM Journal of Fluid Machinery
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• v.10 no.6
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• pp.38-43
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• 2007

Pumps for a turbopump generally operate under high rotational speeds and large head rise conditions. Therefore, reliability is a prime design requirement. Floating-ring type seals are frequently employed in a turbopump because of robustness despite of low hydraulic efficiency. There are many researches on the floating-ring seal itself, but the effects of the floating ring seals on the performance of the whole pump are not widely studied in spite of their importance. In the present study, experimental and computational studies on the effects of the radial clearance of the floating ring seals on the performance of a pump were performed. The experimental results showed that the head rise and efficiency increased as the floating-ring seal clearance was decreased. The results also showed the possibility that the leakage flow which was injected to the inlet of the inducer could enhance the suction performance of the inducer by diminishing the size of the backflows.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.81-84
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• 2000

This paper presents operating process and design method on the linear compressor Stirling cryocooler for cooling infrared detector. The free piston-type Stirling cryocooler, which applies 1) the Stirling cycle for refrigeration, 2) linear motors for driving, 3) flexure bearings for support systems, and 4) fine gap for clearance seals, is the most suitable design for a mechanical cryocooler utilized in a night vision environment.

• Journal of Biosystems Engineering
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• v.12 no.1
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• pp.20-30
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• 1987

Major rice grain losses both in quality and in quantity are incurred in the whitening process which is indispensable in the milling process. Rice whitening it performed by two different whitening actions known as abrasive and frictional. In Korea, abrasive-type whiteners equipped with a emery-stone roller have been adopted in the whitening system in large scale milling plants, but not in customary small scale. However, researches on this type whitener have rarely been conducted in Korea. This study was attempted to establish design criteria or a modified abrasive-type whitener which is aerated with blower. The factors considered in this study were three levels of feedscrew pitch (20, 27, 34 mm) and three levels of clearance(11, 13, 15 mm) between surfaces or emery-stone roller and screen and two levels of moisture content (14.5%, 15.7%, w.b.) of brown rice. Also, the effect of aeration on whitening performance was examined, and a system performance consisting of one pass in the aerated abrasive-type and two passes in the existing friction type was compared with the performance of the existing whitening system consisting of three passes in friction type only. The latter system is prevailed in customery small milling plants. The results of this study are summarized as follows. 1. The interactions between feed-screw pitch and chamber clearance of the aerated abrasive-type whitener had great effect on the performance of the machine. When the value of a nondimensional parameter, $C^2/(P{\cdot}d_p)$, expressing the relations between feed-screw pitch, P, and chamber clearance, C, ranged from 0.40 to 0.45, the performance of the aerated abrasive-type whitener was the best. 2. Aeration to the abrasive-type whitener gave positive effect on milled and head rice recoveries. 3. The whitening system involving the aerated abrasive-type whitener, which has appropriate feed-screw pitch and chamber clearance as described in item 1 above, produced more milled and head rice recoveries by about 1.5% and 2.0%, respectively, than the existing frictional whitening system. The former also consumed less electricity by about 10% (0.9KwH/1000kg).

• Journal of the Korean Society of Costume
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• v.51 no.2
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• pp.53-64
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• 2001

The purpose of this study is to create the program for efficient inventory management and reduction, investigating the present conditions and factors of the inventory throughout current apparel industry. The research method applied in this study is to survey 92 domestic companies which were randomly selected with respect to the kinds of goods produced : men′s wear, women′s wear, and unisex wear. The research can be summarized as follows : 1. The seasonal stock rate of current apparel industry was 28.75%, and the rate of men′s wear companies was higher than that of women′s and unisex wear companies. 19.43% of stock cost reflection rate was applied, and the stack cost of men′s and women′s wear companies was higher than that of unisex wear companies. 2. Periodic bargain sale was the most frequently used way of stock clearance, and "uniform price sale"and outlet stores were the second and the third irrespectively. Unisex wear companies appeared to be more enthusiastic in stock clearance than the companies belonging to the other two categories. The main places for the stock clearance were department stores, outlet stores and enterprises specialized in the stock clearance. 3. QR production was proved to be the most commonly adjusted method of stock reduction, and the emphasis on development of new design and the utilization of stock management system through computer network were the next, While unisex wear companies had established the positive policies, men′s wear companies took lukewarm altitudes in every aspect. The companies selling on an order were 18.64%, and unisex wear companies showed the higher rate. The lead-time after QR production was 10.91 days, and it seemed to take more time for men′s wear companies than for women′s and unisex wear companies. The rate of the chance in stock was proved to decrease by 12.94%, and there was found no meaningful difference among the three categories of apparel companies.

• Journal of Digital Contents Society
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• v.19 no.8
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• pp.1593-1601
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• 2018

The International Hydrographic Organization has developed the S-100 standard as a geospatial standard to express various types of hydrographic information. Product specification describes information of data on ENC such as definition, structure, data model, etc. S-129 PS is for under keel clearance management information. In this paper, to help developers to implement S-129 PS using the technology of S-100, we analyze the process to portray the S-100 based data and then implement a case study. This paper introduces the XSLT processing of portrayal engine to reform the generated data set, and the generation of drawing instructions to display the data set on the electronic chart. A case study is experimented to display the portrayal output of under keel clearance management on an electronic chart.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.268-273
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• 2004

A study on experimental method of the model test for the impulse turbine is carried out. the wave simulator is used to reproduce the real wave condition. It controls two parameter correspond to wave height and wave frequency. The optimum design which is reported by T. Setoguchi is manufactured and tested for the validation of our test facilities. The comparison of model test show that our facilities produce little bit higher efficiency at maximum efficiency point. To increase the efficiency of turbine, the new rotor with negative tip clearance is designed and being tested.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.244-249
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• 2002

It is known that tip clearance flows reduce the pressure rin, flow range and efficiency of the turbomachinery. So, the clear understanding about flow fields in the tip region is needed to efficiently design the turbomachinery. The Navier-Stokes code with the proper treatment of the boundary conditions has been developed to analyze the three-dimensional steady viscous flow fields in the transonic rotating blades and a numerical study has been conducted to investigate the detail flow physics in the tip region of transonic rotor, NASA Rotor 67. The computational results in the tip region of transonic rotors show the leakage vortices, leakage flow from pressure side to suction side and their interaction with a shock Depending on the operating conditions, the position of shock-wave on the blade surface are v8y different close to the blade tip of the transonic compressor rotor. The shock-wave position dose to the blade tip had the dose relationship with the starting position of leakage vortex and the direction of leakage flow.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.141-148
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• 2005

When one opens the door of a microwave oven during operation, microwave might leak through the clearance of the door. Present research has been motivated by the need to reduce the possible clearance by enhancing torsional stiffness of the door of the microwave oven. Static deformation of the door frame of the oven is analyzed under a door-opening force. On the basis of the topological optimization, the right flange of the door frame is shown to need reinforcing. Several types of reinforcing brackets weldable to the right flange is proposed, and their effects to the stiffness of the door frame are compared and evaluated.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.105-114
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• 1998

Flow field and near-field noise of a centrifugal fan has been studied with an efrcient compressible method and STAR-CD. The flow field of the centrifugal fan is assumed two-dimensional. Most of the compressible studies has been done by inviscid solver because viscous simulation shows little difference. The near field noise is estimated in term s of sound pressure level in frequency domain transformed from the computed pressure fluctuations using FFT. The simulation has been done on various design elements such as impeller blade shapes, the number of blades and cut-off clearance. The comparison shows that the number of blades has a significant effect on near-field noise without losing aerodynamic performance.

• Journal of Power System Engineering
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• v.15 no.4
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• pp.60-64
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• 2011

Computer-aided engineering (CAE) is the broad usage of computer software to aid in engineering tasks. It includes computer-aided design (CAD), computer-aided analysis (CAA), computer-integrated manufacturing (CIM), computer-aided manufacturing (CAM), material requirements planning (MRP), and computer-aided planning (CAP). In this study, the stress of mold analyzed using CAE technique. Punch loads were same difference between 0.5 % and 1.0 % of clearance, but punch load was decreased according to increasing of clearance. Punch load of pre-piercing process worked a little smaller than piercing process. Therefore, the hole of fine blanking process is also more efficient to manufacture the true size after pre-piercing.