• Communications for Statistical Applications and Methods
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• v.5 no.1
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• pp.231-238
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• 1998

A two stage shrinkage testimator for the mean of an exponential distribution is considered with the assumption that an initial estimate of the mean is available. Mean squared error(MSE) of testimator and its relative efficiency (to usual single sample mean) are briefly reviewed. It is shown that relative efficiency depends only on the ratio of true mean value and its initial estimate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1374-1379
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• 2003

In this paper, twoㆍstage low noise amplifier(LNA) for 24㎓ is designed and fabricated using NE450284C HJ-FET of NEC CO. In order to get noise figure and input VSWR to be wanted it is considered input VSWR and noise figure simultaneously in matching-circuit designing. The fabricated two-stage low noise mph u has the gai of 16.6㏈, input VSWR of 1.6, and output VSWR under 1.5.

• Journal of the Korean Statistical Society
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• v.16 no.1
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• pp.37-44
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• 1987

A two-stage selection procedure is considered in the case of exponential populations with common known scale parameter. The proposed procedure is designed following the lines of Tamhane and Bechhofer(1977). The design constants to implement the procedure are provided. Monte Carlo results show that the proposed procedure performs better than the single procedure by Raghvachari and Starr (1970) in terms of the expected total sample size.

• The Korean Journal of Applied Statistics
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• v.11 no.2
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• pp.403-413
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• 1998

Sample size determination is a crucial part of sampling design. This paper gives a assessment for sample size determination using two-stage sampling scheme for estimating the population mean with a given precision.

• Communications for Statistical Applications and Methods
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• v.6 no.3
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• pp.749-754
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• 1999

The cost is known to be proportional to the size of sample. We consider a cost function of the form Cost=c1np+c2npmq where c1, c2 p, and q are all positive constants. This cost function is to be used in finding an optimal allocation in two-stage cluster sampling. The optimal allocations of n and m gives the properties of uniqueness under some conditions and of monotonicity with p>0 when q=1.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.777-786
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• 2007

This paper presents a modified simulated annealing algorithm to optimize linear scheduling projects with multiple resource constraints and its effectiveness is verified with a proposed problem. A two-stage solution-finding procedure is used to model the problem. Then the simulated annealing and the modified simulated annealing are compared in the same condition. The comparison results and the reasons of improvement by the modified simulated annealing are presented at the end.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.392-399
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• 2013

This study aimed to investigate responses of photosynthesis, plant growth, and phytochemical contents to different artificial light sources for 'Seneca RZ' and 'Gaugin RZ' two butterhead lettuce (Lactuca sativa L.). In this study, fluorescent lamps (FL), three colors LEDs (red, blue and white, 5 : 4 : 1; RBW) and metalhalide lamps (MH) were used as artificial lighting sources. Photoperiod, air temperature, relative humidity, EC, and pH in a cultivation system were maintained at 16/8 h, $25/15^{\circ}C$, 60~70%, $1.4{\pm}0.2dS{\cdot}m^{-1}$, and $6.0{\pm}0.5$, respectively. The photosynthetic rate of both two butterhead lettuce were the highest under RBW in middle growth stage. However, in late growth stage, the photosynthetic rate of both two butterhead lettuce were higher under RBW and MH than FL. The light sources showed significant results for plant growth but those effects were different to variety. Fresh and dry weight of 'Gaugin RZ' butterhead lettuce under MH were heavier than other lights in all growth stages. Growth of 'Seneca RZ' butterhead lettuce was maximized highest under MH in middle growth stage and FL in late growth stage. In the leaf tissue of 'Seneca RZ' butterhead lettuce, tipburn symptom occurred under all light sources and in the leaf tissue of 'Gaugin RZ' butterhead lettuce, it occurred under two light sources except for fluorescent lamps in late growth stage. kinds of lamp affect plant growth more than plant quality. Relative growth rate of both two butterhead lettuce was faster in middle growth stage than late stage. Growth of 'Gaugin RZ' was shown by kinds of lamp in middle growth stage and but it was not significantly affected by light sources and variety in late stage. Most of the phytochemical contents of two butterhead lettuce were significantly affected by different light sources. Contents of all vitamins showed higher than other light sources on RBW for both two lettuce, especially ${\beta}$-Carotene content of 'Gaugin RZ' was the highest. Plant growth, photosynthesis, and phytochemical contents were observed significant effects by different light sources for two butterhead lettuce but those effects were highly different between variety and kinds of phytochemicals. Therefore, the selection of optimum light source should be considered by variety and kinds of phytochemicals in the plant factory.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.371-380
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• 1998

The flow patterns and dynamic properties of ship's propulsion mechanism of two-stage Weis-Fogh type are studied by the discrete vortex method. In order to study the effects of the interaction of the two wings two cases of the phase differences of the wing's motion are considered the same phase and the reverse phase. The flow patterns by simulations correspond to the photographs obtained by flow visualization and flowfield of the propulsion mechanism which is unsteady and complex is clearly visualized by numerical simulations. The time histories of the thrust an the drag coefficients on the wings are also calculated and the effects of the interaction of the two wings are numerically clarified.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.694-700
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• 1998

PSC box bridge by MSS construction method may not be set at cross section at one step. Web and bottom flange(U member) would be set at first, top flange will be set later with a time lag. In this case, U member and top flange concrete have different strain history. As two different aged section behaves as the composite section, there would happen the redistribution of stress. This is come from time-dependent strain characteristics of concrete itself. In this study, two models are considered, one with considering the set time of cross section and the other without. By performing longitudinal analysis of two models on considering construction stage, the stress differences of two are compared. As the analysis results show a considerable differences in the stresses of cross section between two models, the set time of cross section is needed for rational design f PSC box girder bridge.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.227-233
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• 2002

It is common for highly loaded supersonic stage to have very high relative inlet Mach number. To get this level of inlet Mach number, rotor blade outer diameter or rotational speed should be increased. In the case of commercial turbo-fan engine, it is preferred to make the rotor blade outer diameter large than increasing the rotational speed. But, for multi-stage fan of military engines, overall diameter is often restricted and they are apt to increase the rotational speed. With high rotational speed, relative inlet Mach number is likely to be well supersonic over the entire rotor blade span and the characteristic of the stage is affected with meridional shape of the stage, especially at near hub or tip. In this paper, the aerodynamic performance of two different hub surface shape is compared and it's merit and demerits were discussed.