• Journal of the Korean Statistical Society
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• 제30권3호
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• pp.453-465
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• 2001

It is often the case that one wants to estimate parameters of the distribution which follows certain parametric model, while the dta are contaminated. it is well known that the maximum likelihood estimators are not robust to contamination. Basuet al.(1998) proposed a robust method called the minimum density power divergence estimation. In this paper, we investigate data-driven selection of the tuning parameter $\alpha$ in the minimum density power divergence estimation. A criterion is proposed and its performance is studied through the simulation. The simulation includes three cases of estimation problem.

• Journal of electromagnetic engineering and science
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• 제5권2호
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• pp.97-103
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• 2005

This paper describes the measured results of sonobuoy transmitting antenna system for anti-submarine warfare (ASW). Since radiation pattern and power density depend on impedance matching between transmitting RF part and antenna with termination resistance, design of matching circuit is very important for sonobuoy system performance. Matching circuit is designed by Smith chart using control of L and C. In standing wave ratio(SWR) measurement using Network Analyzer, SWR of antenna with matching circuit observed 1.5 below at the assigned VHF band. It shows very excellent performance comparison with conversional product that is used for the same object. The measured vertical and horizontal radiation patterns are also shown the satisfaction of military specifications. A drop out of sonobuoy system on the sea is happened when angle of elevation direction is over 10 degrees, and it is conformed that it takes less than I second return to original signal level. The required electric power density is $83\;mW/m^2$ in the military specification, and measured electric power density is observed over average $110\;mW/m^2$ at all frequency bands.

• 한국안전학회지
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• 제34권1호
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• pp.1-7
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• 2019

Electromagnetic measurements of the power cable tunnel were conducted from August 10 to 20, 2018, in the ${\bigcirc}{\bigcirc}$ city underground utility tunnel. During this period, the average temperature was $31.89^{\circ}C$ and the humidity was 67.56% in power cable tunnel. As a result of the electromagnetic measurement, the highest electric field was 25.3 V/m and the magnetic flux density was $42.6{\mu}T$. The average electric field was 18.56 V/m and the magnetic flux density was $29.32{\mu}T$ in the power cable tunnel. As a result of comparison with the electric equipment technical standard, the electric field in the power cable tunnel was 0.5% of the electric equipment standard and 35.2% of the magnetic flux density. It's similar value that electric field is about robotic vacuum(15.53 V/m), and magnetic flux density is similar value about capsule- type coffee machine ($23.07{\mu}T$). The number of cable lines and the size of the electromagnetic waves were not proportional to each other through comparison of cable lines in the power cable tunnel. It was confirmed that 154 kV, rather than 22.9 kV, could have a greater influence on occupational.

• 대한전자공학회논문지SD
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• 제41권4호
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• pp.67-74
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• 2004

기존의 버스트 모드 자동전력제어 회로는 데이터 율이 증가함에 따라 마크밀도 변화 영향을 심하게 받아 에러를 야기하였다. 이 문제를 해결하기 위해 높은 데이터 율에서도 마크밀도의 영향을 배제시킬 수 있는 새로운 구조의 첨두 비교기를 고안하고 이를 자동전력제어 회로에 적용하여 마크밀도 변화에 강한 버스트 모드 자동전력제어 회로를 제안하였다. 제안한 자동전력제어 회로 내의 첨두 비교기는 높은 데이터 율에서 뿐만 아니라 광범위한 기준전류 및 차 전류 변화에서도 미소한 마크밀도 변화 영향만을 보여 마크밀도 변화에 매우 강한 특성을 확인 할 수 있었다.

• 한국정보처리학회논문지
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• 제6권3호
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• pp.766-772
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• 1999

With the increase of portable system and high-density IC, power consumption of VLSI circuits is very important factor in design process. Power estimation is required in order to estimate the power consumption. A simple and correct solution of power estimation is to use circuit simulation. But it is very time consuming and inefficient way. Probabilistic method has been proposed to overcome this problem. Transition density using probability was an efficient method to estimate power consumption using BDD and Boolean difference. But it is difficult to build the BDD and compute complex Boolean difference. In this paper, we proposed Propowest. Propowest is building a digraph of circuit, and easy and fast in computing transition density by using modified COP algorithm. Propowest provides an efficient way for power estimation.

• Journal of Welding and Joining
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• 제10권2호
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• pp.19-31
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• 1992

A numerical study was performed to investigate the flow field and the heat transfer characteristics occurring in high power density welding which is important in many fields of engineering applications. A two dimensional quasi-steady state of keyhole welding model is simulated by using the finite volume methods. It is shown that the shape of isothermal line is elliptic and the temperature gradient is very steep compared with other welding method and the welding speed has on welding width and observed beam power.

• 조명전기설비학회논문지
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• 제25권12호
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• pp.42-47
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• 2011

The design of road lighting is aiming illuminance and luminance requirements for road lighting. In the process, various factors associated with luminaires such as luminous efficacy, light distribution, mounting height, spacing and maintenance factor are considered. However, there has been no restriction on lighting power density. In this study, lighting power density has been comparatively analyzed through a study of related data and a result of measurements on domestic roads. And, it has been analyzed by simulation results for road in which lighting conditions are variable. In terms of the limitation on power density for road lighting, road lighting can be designed using high efficacy lighting systems for energy saving.

• 전력전자학회논문지
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• 제21권5호
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• pp.381-387
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• 2016

Many efforts have focused on the improvement of power density and efficiency by downsizing the motor and inverter. Recently, Toyota, Honda, and GM realized that the compact-sized motor uses the hairpin structure with increased space factor. Reducing the maximum torque from high-speed technique also makes it possible to design the high-power density model. Toyota and Honda used the newly developed power semiconductor IGBT to decrease conduction loss for high-efficiency inverter. In particular, Toyota used the boost converter to increase the DC link voltage for high efficiency in low-torque high-speed region. Toyota and GM also used the double-sided cooling structure for miniaturization of inverter for high-power density.

• Journal of Power Electronics
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• 제12권3호
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• pp.487-494
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• 2012

A new low cost high power density photovoltaic power conditioning system (PV PCS) with an energy storage system is proposed in this paper. Its high power density and cost effectiveness can be achieved through the unification of the maximum power point tracker and the battery charger/discharger. Despite the reduced power stage, the proposed system can achieve the same performance in terms of maximum power point tracking and battery charging/discharging as the conventional system. When a utility power failure happens, the proposed system cannot perform maximum power point tracking at the UPS mode. However, the predetermined battery voltage near the maximum power point of the PV array can effectively generate a reasonable PV power even at the UPS mode. Therefore, it features a simpler structure, less mass, lower cost, and fewer devices. Finally, to confirm the operation, validity, and features of the proposed system, a theoretical analysis and experimental results from a single phase AC 220Vrms/1.5kW prototype are presented.

• 한국진공학회지
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• 제8권3B호
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• pp.353-360
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• 1999

The global balance model is applied to investigate the transient behavior of the electron density and temperature in helicon plasmas. The power absorption calculated from the solutions of the Maxwell equations is used in solving the power balance equation. A balance model for the neutral gas is also considered to fins its density self-consistently. It is turned out that the numerical results reasonably explain consequences of the ion pumping effect including the occurrence of two distinct modes of pulsed helicon discharge which have been observed experimentally. The behavior of the discharge parameters are fond to be primarily dependent on the power absorption and the gas flow rate, but the pressure controls the electron density and temperature of the final steady state as well as the transient state even with the same flow rate. Finally, it is shown that the electron density virtually the linear relationship between the density and the magnetic field is retained for a higher pressure when the effect of the ion pumping is negligible.