• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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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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• 제19권5호
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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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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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.

• 한국잠사곤충학회지
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• 제5권
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• pp.19-23
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• 1965

가잠을 이중교배함으로씨 발생하는 형질을 조사한 결과 다음 결과를 얻었다. 1. 10분간 이중교배한 결과 그 형질이 잠품종에 따라 변화하였다. 그러므로 잠종제조에 있어서 자유교미를 절대적으로 방지하여야 한다. 2. 동품종과 이품종간의 수정력강도에 일정한 경향을 발견하기가 곤란하다. 그리고 먼저 사정된 정자가 뒤에 사정된 정자보다 우위를 차지한다고 보기 곤란하다.

• 조명전기설비학회논문지
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• 제28권7호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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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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• 제30권4호
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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.

• 천문학회보
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• 제46권1호
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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.

• 한국광학회지
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• 제22권1호
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• pp.46-52
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• 2011

본 연구에서는 레버 증폭 구조를 이용한 플렉서 기반의 나노 스테이지를 설계, 제작하였다. 제작된 나노 스테이지를 샘플 스테이지로 채용한 공초점현미경을 개발하였다. 2차원 이미징의 구현을 위해서, 기존의 공초점현미경은 레이저를 이미징 평면상에 스캐닝하는 방식으로 구현된다. 본 연구에서는 백 나노미터의 구동정밀도를 가지는 나노 스테이지 위에 놓인 샘플을 2차원으로 스캐닝하면서 2차원 이미지를 구현할 수 있는 공초점현미경을 개발하였다. 플렉서 기반의 나노 스테이지는 이중 판스프링, 변위증폭 레버, PZT 엑추에이터 그리고 변위 센서로 구성 되어 있다. 스테이지의 구동 성능 해석을 위해 상용 유한요소 해석 프로그램을 이용하였다. 현미경에 사용되는 광원은 적색광 레이저이며, 레이저는 여러 광학요소를 거쳐 샘플스테이지의 샘플에 입사되고, 반사된 빛은 광센서인 PMT(Photo Multiplying Tube)로 계측되게 된다. 계측된 빛의 크기를 이용하여서 2차원 이미징을 구현하였다. 개발된 공초점 현미경으로 생쥐 귀의 피부조직을 관찰하여 현미경의 이미징 성능을 검증하였다. 설계된 샘플 스테이지는 기존의 공초점 현미경의 기계적인 Beam 스캐너를 대신함으로써 현미경의 광경로 및 전체시스템을 간소화 하였다.

• Journal of information and communication convergence engineering
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• 제14권1호
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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.