• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.162-168
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• 2000

This paper conducted experimental study of turbulent diffusion flame, equipped with a unique double swirler combustor for gas fuel. The burner has two vane swirlers which are fitted to primary, secondary air channel. Temperature, and NOx emission concentrations are measured in combustion flame region and velocity in cold flow for various primary/secondary air ratio conditions. The results showed the characteristics of swirl flame and decreasing NOx concentrations with increasing primary/secondary air ratio.

• Communications for Statistical Applications and Methods
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• v.19 no.5
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• pp.663-671
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• 2012

In the present study, a combined ratio cum regression estimator is proposed to estimate the population mean of the study variable in the presence of a non-response using an auxiliary variable under double sampling. The expressions of bias and mean squared error(MSE) based on the proposed estimator is derived under double (or two stage) sampling to the first degree of approximation. Some estimators are also derived from the proposed class by allocating the suitable values of constants used. A comparison of the proposed estimator with the usual unbiased estimator and other derived estimators is carried out. An empirical study is carried out to demonstrate the performance of the suggested estimator and of others; it is endow that the empirical results backing the theoretical study.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.395-398
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• 2002

This paper presents generalized small-signal models for complementary driven double-ended isolated converters. The proposed small-signal models include the effect of the parasitic resistances, which have dominant influence on the damping of the secondary Power stage double-pole. To confirm the validity of the new models, an asymmetrical half-bridge converter with confer-taped rectifier and a forward-flyback converter with current doubler rectifier were built, and their performance were compared with the theoretical prediction.

• Journal of Sericultural and Entomological Science
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• v.5
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• pp.19-23
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• 1965

Author studied to investigate the form and character of silkworm, Bombyx mori L. which bred from double copulation. The results obtained are as follows. 1. Some eggs of silkworm were fertilized evenly 10 minutes copulation, but it was varried by the race of the worm. In silkworm eggs production, the male and female should be separated from the early stage of 5th instar in order to do not make non hybrid eggs. 2. It was very difficult to find the tendency of fertilization ratio between homo race copulation and hetero race copulation in crossing with mates of two different race for a female (double crossing).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.62-68
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• 2014

We proposed a series connection-type superconducting fault current limiter(SFCL) using E-I core that can prevent the internal magnetic flux generation of cores during normal operation, and prevent the saturation of cores due to a sudden magnetic flux generation at the initial stage of fault occurrence while limiting the peak current. Through a short-circuit simulation experiment, we analyzed the operating status of the two superconducting elements and limiting characteristics according to the size of the fault current peak before and after the failure. Further, the double peak current limiting characteristics according to the winding directions as well as the current and the voltage of each coil were compared and analyzed.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1401-1403
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• 2005

This paper presents generalized small-signal models for asymmetrically-driven double-ended dc-to-dc converters. The proposed small-signal models include the effects of the parasitic resistances, which have dominant influence on the damping of the secondary power stage double-pole. To confirm the validity of new models, an asymmetrical half-bridge converter with center-taped rectifier and a forward-flyback converter with current doubler rectifier were built, and their performances were compared with the theoretical predictions.

• Communications for Statistical Applications and Methods
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• v.30 no.4
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• pp.403-410
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• 2023

Two-Phase sampling, which was first introduced by Neyman (1938), has various applications in different forms. Variance estimation for two-phase sampling has been an important research topic because conventional variance estimators used in most softwares are not working. In this paper, we considered a variance estimation for two-phase sampling in which stratified two-stage cluster sampling designs are used in both phases. By defining a conditionally unbiased estimator of an approximate variance estimator, which is calculable when all elements in the first phase sample are observed, we propose an explicit form of variance estimator of the double expanded estimator for a two-phase sample. A small simulation study shows the proposed variance estimator has a negligible bias with small variance. The suggested variance estimator is also applicable to other linear estimators of the population total or mean if appropriate residuals are defined.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.34.1-34.1
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• 2021

Abell 1240 is a merging galaxy cluster hosting prominent, symmetric double radio relics. To constrain its merging history, we provide the first weak-lensing analysis of the dark matter distribution of the Abell 1240 field with Subaru/Suprime-Cam observations after robustly addressing instrumental systematics. We also investigate the cluster galaxy distributions, combining our new MMT/Hectospec observations and the spectroscopic redshifts from the literature. Both weak-lensing mass reconstruction and galaxy distribution show that Abell 1240 consists of two subclusters stretched north to south between the double radio relics. We quantify the significance of the substructures and present their mass estimates. Finally, we discuss a merging stage of Abell 1240 with the current weak-lensing results and the radio relic priors.

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.46-52
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• 2011

A confocal microscope was developed utilizing a scanning sample stage based on a home-built double-compound flexure guide. A scanning sample stage with nano-scale resolution consisted of a double leaf spring based flexure, a displacement amplifying lever, a Piezo-electric Transducer(PZT) actuator and capacitance sensors. The performance of the two-axis stage was analyzed using a commercial finite element method program prior to the implementation. A single line laser was employed as the light source along with the Photo Multiplier Tube(PMT) that served as the detector. The performance of the developed confocal microscope was evaluated with a mouse ear skin imaging test. The designed scanning stage enabled us to build the confocal microscope without the two optical scanning mirror modules that are essential in the conventional laser scanning confocal microscope. The elimination of the scanning mirror modules makes the optical design of the confocal microscope simpler and more compact than the conventional system.

• Journal of information and communication convergence engineering
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• v.14 no.1
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• pp.1-8
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• 2016

Spectrum sensing in cognitive radio networks allows secondary users to sense the unused spectrum without causing interference to primary users. Cognitive radio requires more accurate sensing results from unused portions of the spectrum. Accurate spectrum sensing techniques can reduce the probability of false alarms and misdetection. In this paper, a two-stage spectrum sensing scheme is proposed for cooperative spectrum sensing in cognitive radio networks. In the first stage, spectrum sensing is executed for each secondary user using energy detection based on double adaptive thresholds to determine the spectrum condition. If the energy value lies between two thresholds, a fuzzy logic scheme is applied to determine the channel conditions more accurately. In the second stage, a fusion center combines the results of each secondary user and uses a fuzzy logic scheme for combining all decisions. The simulation results show that the proposed scheme provides increased sensing accuracy by about 20% in some cases.