• Communications for Statistical Applications and Methods
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• 제28권5호
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• pp.425-445
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• 2021

A generalization of the log-logistic (LL) distribution called exponentiated log-logistic (ELL) distribution on lines of exponentiated Weibull distribution is considered. In this paper, based on progressive type-II censored samples, we have derived the maximum likelihood estimators and Bayes estimators for three parameters, the survival function and hazard function of the ELL distribution. Then, under the balanced squared error loss (BSEL) and the balanced linex loss (BLEL) functions, their corresponding Bayes estimators are obtained using Lindley's approximation (see Jung and Chung, 2018; Lindley, 1980), Tierney-Kadane approximation (see Tierney and Kadane, 1986) and Markov Chain Monte Carlo methods (see Hastings, 1970; Gelfand and Smith, 1990). Here, to check the convergence of MCMC chains, the Gelman and Rubin diagnostic (see Gelman and Rubin, 1992; Brooks and Gelman, 1997) was used. On the basis of their risks, the performances of their Bayes estimators are compared with maximum likelihood estimators in the simulation studies. In this paper, research supports the conclusion that ELL distribution is an efficient distribution to modeling data in the analysis of survival data. On top of that, Bayes estimators under various loss functions are useful for many estimation problems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.129-131
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• 2007

In this paper, we research improvement in efficiency of single-phase induction motor by adapting the condition of the balanced and quasi-balanced operation. we maintain turns of auxiliary winding of the motor and adjust resistance and reactance. In this condition, resistance value and copper loss are much gloater. Namely, this is the condition only for balancing MMF without consideration of copper loss of stator winding. To make more practical design, therefore, we will perform winding design which is based on balanced operation condition and applies copper loss minimum. The problem of deterioration of starting torque is completed by rotor bar shape design.

• Journal of the Korean Statistical Society
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• 제32권3호
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• pp.289-298
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• 2003

We consider the estimation problem for the scale parameter of the Rayleigh distribution using weighted balanced loss function (WBLF) which reflects both goodness of fit and precision. Under WBLF, we obtain the optimal estimator which creates a kind of balance between Bayesian and non-Bayesian estimation. We also deal with the estimation of R ＝ P(Y < X) when Y and X are two independent but not identically distributed Rayleigh distribution under squared error loss function.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2022년도 추계학술대회
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• pp.164-166
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• 2022

Long-tail problem은 class 별로 sample의 개수에 차이가 있어 성능에 안 좋은 영향을 미치는 것을 말한다. 본 논문에서는 cost-sensitive learning 중 Class-Balanced Loss를 이용해 성능을 개선하여 Long-tail problem을 해결하려고 한다. 먼저, balanced data set과 imbalanced data set의 성능 차이를 살펴보도록 할 것이다. 그 후, Class-Balanced Loss를 3가지 버전으로 이용해 그 성능을 측정하고 분석해 볼 것이다.

• 전기학회논문지
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• 제57권9호
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• pp.1536-1545
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• 2008

In this paper, we research a new method for efficiency improvement of a single-phase Induction motor by minimization of the stator loss. To make this, we perform winding design which is based on balanced and quasi-balanced operation condition. It gives efficiency improvement greatly but poor starting torque simultaneously. To obtain the best efficiency improvement maintaining the maximum and starting torque, the optimal winding specification and rotor dimension is determined with variation of secondary resistance, running capacitor and turn ratio. Finally, this paper gives the comparison between the simulation results and experimental results.

• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.65-70
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• 2017

The design and implementation aspects of a new single-balanced mixer for ultra-wideband (UWB) applications are presented in this study. The proposed mixer utilizes a miniaturized UWB ring coupler as a balun, consisting of a pair of in-phase and inverted-phase transitional structures. The well-balanced UWB performance of the ring coupler, aside from the optimized diode matching, results in improved conversion loss and inter-port isolations for a wide bandwidth. The size of the implemented single-balanced diode mixer is reduced to about 60% of the area of the conventional single-balanced ring diode mixer. The measured results of the proposed mixer exhibit an average conversion loss of 7.5 dB (minimum 6.7 dB) and a port-to-port isolation of greater than 18 dB over a UWB frequency range of 3.1-10.6 GHz. The measured results agree well with the simulated results.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.15-20
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• 2000

We demonstrated a single balanced mixer of the combination of high-T. superconductor (HTS) and III-V GaAs beam lead Schottky diodes operating in the mini-cryogenic chamber. The HTS hybrid mixer was designed with a center frequency of 27.5 GHz and a bandwidth of 1 GHz, and consisted of a rat-race coupler circuit with beam-lead diodes attached to its balanced ports. The HTS hybrid mixer with 1 GHz RF bandwidths exhibits a conversion loss of 6 dB. A LO-to-RF isolation was greater than 40 dB in the range of operating frequencies. Since the HTS/III-V hybrid mixer devices have lower noise and conversion loss, this technique provide us with new capabilities that can be effectively utilized in the field of local-point distribution service (LMDS) systems.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권4호
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• pp.217-222
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• 2006

A distributed balun such as Marchand balun typically shows good phase and amplitude balances, but its size is somewhat large especially in lower frequency band. In contrast, a lumped balun has compact size but its performance is not good compared with that of a distributed one. In this paper the distributed-coupled line can be reduced effectively by using the lumped-distributed implementation. Designed balun has two coupled line of each ${\lambda}/72$ and shows magnitude balance of 0.05 dB, phase balance of $0.7^{\circ}$ in passband. Balanced-type filter is designed using balun and it has insertion loss of 8 dB, return loss of 7 dB, magnitude balance of 0.2 dB, and phase balance of $1.2^{\circ}$ in passband.

• 전력전자학회논문지
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• 제18권5호
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• pp.492-500
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• 2013

A balanced forward-flyback converter for high efficiency and high power factor using a foward and flyback converter topologies is proposed in this paper. The conventional AC/DC flyback converter can achieve a good power factor but it has the high offset current through the transformer magnetizing inductor, which results in a large core loss and low power conversion efficiency. And, the conventional forward converter can achieve the good power conversion efficiency with the aid of the low core loss but the input current dead zone near zero cross AC input voltage deteriorates the power factor. On the other hand, since the proposed converter can operate as the forward and flyback converters during switch turn-on and turn-off periods, respectively, it cannot only perform the power transfer during an entire switching period but also achieve the high power factor due to the flyback operation. Moreover, since the current balanced capacitor can minimize the offset current through the transformer magnetizing inductor regardless of the AC input voltage, the core loss and volume of the transformer can be minimized. Therefore, the proposed converter features a high efficiency and high power factor. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

• 응용통계연구
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• 제27권6호
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• pp.1017-1028
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• 2014

잘 알려져 있는 것처럼 일반적인 베이즈 추정량(Bayes estimator)과 경험적 베이즈 추정량(empirical Bayes estimator)은 모수를 추정하는데 있어서 오차를 과다축소하는 단점을 가지고 있다. 따라서 이러한 단점을 극복하기 위하여 constrained 베이즈 추정량이 일차 적률과 이차 적률을 일치시키는 성질을 만족시키며 제안되었다. 또한 평균 제곱오차 함수와 같은 전통적인 손실함수에서는 추정의 정확성만을 고려하는 특징을 가지고 있기 때문에, 추정의 정확성과 정합성을 동시에 고려하는 균형 손실함수가 제안되었다. 이러한 이유로 인하여 균형손실 함수하에서의 제한적 베이즈 추정량의 활용이 손해 보험의 가격 산출에 제안되는 것은 타당하다. 그러나 대부분의 연구는 추정의 문제에만 집중하는 경향이 있으며. 이는 새롭게 제안되는 특정 손실함수하에서의 constrained 베이즈 추정량과 constrained empirical 베이즈 추정량의 베이즈 위험의 계산이 어렵다는 점에서 기인한다. 본 연구에서는 다양한 베이즈 추정량들에 대한 베이즈 위험을 서로 다른 두 손실함수하에서 비교하였으며, 그 대상은 자동차 보험 산업에서의 위험도 추정 분야이다. 또한 자동차 보험 산업의 실제 사고 데이터를 이용하여 새롭게 제안된 베이즈 추정량의 베이즈 위험을 비교함으로써 그 효용성을 입증하였다.