• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.2
• /
• pp.48.1-48.1
• /
• 2015

Active galactic nuclei (AGNs) are powered by a supermassive black hole with an accretion disk and exhibit prominent broad and narrow emission lines. The unification model AGNs requires the presence of a geometrically and optically thick torus component that hides the broad line region from observers lying in the equatorial direction. The strong far UV radiation characterizing AGN spectra is expected to be scattered inelastically in the torus region to reappear around hydrogen Balmer lines or Paschen lines in the form of broad wings. Adopting a Monte Carlo technique we produce broad wings around $H{\alpha}$, $H{\beta}$ and $Pa{\alpha}$ that are formed through Raman scattering. The widths of the wings are mainly affected by the neutral column density of the torus, and the overall strengths are primarily determined by the covering factor and the column density of the neutral region. It is concluded that deep spectroscopy of AGNs of broad wings around hydrogen emission lines may shed much light on the AGN unification model.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.3
• /
• pp.651-656
• /
• 2010

This paper proposes a new dynamic PCA algorithm to recognize types of electric poles, which is necessary for a mobile robot moving along the neutral line for inspecting high-voltage facilities. Since the mobile robot needs to pass over the electric poles and grasp the neutral wire again for the next region inspection, the detection of the electric pole type is a critical factor for the successful passing-over the electric pole. The CCD camera installed on the mobile robot captures the image of the electric pole while it is approaching to the electric pole. Applying the dynamic PCA algorithm to the CCD image, the electric pole type has been classified to provide the stable grasping operation for the mobile robot. The new dynamic PCA algorithm replaces the reference image in real time to improve the robustness of the PCA algorithm, adjusts the brightness to get the clear images, and applies the Laplacian edge detection algorithm to increase the recognition rate of electric pole type. Through the real experiments, the effectiveness of this proposed dynamic PCA algorithm method using Laplacian edge detecting method has been demonstrated, which improves the recognition rate about 20% comparing to the conventional PCA algorithm.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.500_502
• /
• 2009

한전의 분산전원 연계규정에 따르면 수전고객은 변압기 결선이 ${\triangle}-Yg$ 주로 사용되나 분산전원 연계선로는 변압기 결선이 $Yg-{\triangle}$ 형태로 연계되어 있다. 전원계통 고장시 ${\triangle}-Yg$ 결선 방식은 역조류가 발생되지 않으나, $Yg-{\triangle}$ 결선방식은 중성선을 통해 최대 2000[A]까지 역으로 고장전류를 공급한다[1]. 이때 보호계전기 오동작뿐만 아니라 연계용변압기, 케이블 등 설비보호를 위해서는 고장전류의 크기를 반드시 제한해야 된다. 본 논문은 연계용변압기에 의해서 공급되는 중성선의 과전류 현상을 해석하고, 이론적으로 해석된 결과를 PSCAD/EMTDC로 검증하였으며 고장전류의 크기를 저감하기 위해 NGR 저항 값을 조절하면서 고장전류의 크기를 시뮬레이션 하였다. 분산전원 연계선로에서 영상분 고장전류의 크기를 저감하는 방법으로 연계용 변압기($Yg-{\triangle}$) 1차 측에 중성선에 NGR(Neutral Grounding Reactor; 중성점 접지리액터)을 설치해야 하며 영상임피던스를 조절하는 방법을 제시하였다.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.1
• /
• pp.167-174
• /
• 2016

The Korean distribution line currently consists of overhead ground wires (OHGW), overhead distribution lines, neutral wires (NW), and messenger wires (MW). The MW is installed under the NW. The lightning protection system in Korea is focused on OHGW and lightning arrester and the MW are not considered. Therefore, this paper proposes the applicability of MW for purpose of lightning protection. For this, we analyzed the effects of lightning overvoltage according to the existence of OHGW and MW and the grounding conditions of the MW in the Korean distribution system. The grounding conditions of the MW that we took into consideration were the common or separate grounding of the MW and NW. The analysis based on the equivalent circuit of the distribution pole at each condition was performed. The distribution lines and lightning were modeled using the Electromagnetic Transients Program (EMTP). For each of the installation conditions of the OHGW and MW, the various lightning conditions were simulated and analyzed for both direct and indirect lightning. The simulation results showed that, if the OHGW was not installed in the Korean distribution system, the lightning overvoltage could be reduced by the common grounding of the MW and NW.

• Journal of Mechanical Science and Technology
• /
• v.18 no.6
• /
• pp.972-978
• /
• 2004

Forward slip is an important parameter often used in rolling-speed control models for tandem hot strip rolling mills. In a hot strip mill, on-line measurement of strip speed is inherently very difficult. Therefore, for the set-up of the finishing mill, a forward slip model is used to calculate the strip speed from roll circumferential velocity at each mill stand. Due to its complexity, most previous researches have used semi-empirical methods in determining values for the forward slip. Although these investigations may be useful in process design and control, they do not have a theoretical basis. In the present study, a better forward slip model has been developed, which provides for a better set-up and more precise control of the mill. Factors such as neutral point, friction coefficient, width spread, shape of deformation zone in the roll bite are incorporated into the model. Implementation of the new forward slip model for the control of a 7-stand hot strip tandem rolling mill shows significant improvement in roll speed set-up accuracy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.6
• /
• pp.107-114
• /
• 2010

Lightning is the discharging of high-voltage charged cells within clouds to earth other or to the earth. Lightning protection grounding is essential for the protection of buildings, distribution lines, and electrical equipment from lightning surges. Equipment grounding is for the purpose of controlling the voltage to earth within predictable limits. This paper investigates the effects of lightning arrester grounding resistance by analysing the neutral to earth voltages and arrester break down voltages when the lightning strike hits the distribution line. The case study was simulated numerically and graphically through the use of the EDSA software program.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.12 no.4
• /
• pp.540-547
• /
• 2009

In the near future, military robots are likely to be substituted for military personnel in the field of battle. The power system of a legged robot is considerably more complex than the one used for a land vehicle because of the coordination and stability issues due to the large number of degree of freedom. In this paper, a servovalve-piston combination system for a straight-line motion of robot leg is modeled as three degree of freedom based on double inputs and single output transfer function. The output is the displacement of piston from neutral. The inputs are valve displacement from neutral and arbitrary load force in this system. LQR(Linear Quadratic Regulator) technique is applied in order to achieve robust stability and fast responses of the system. The Kalman filter loop, rejection of disturbance and noise, riccati equation, filter gain matrix, and frequency domain equality are analyzed and designed.

• Journal of the Korean Society of Costume
• /
• v.54 no.6
• /
• pp.13-23
• /
• 2004

To date, Italian fashion rans the top even its rise is far behind Paris and New York. The purpose of this study is to analyze and compare the aesthetic characteristics of the italian fashion through two representative designers who contributed to italian fashion. Italy had unique industrial system and craftsmanship from the history and sense of the beauty and the uniqueness from the culture. After the World War II, Italy started to produce elegant sportswears influenced by the progressive manufacturing techniques and practical culture of America. Italian fashion of 'easy elegance' is spearheaded by Vesace and Armani. The aesthetic characteristics of Italian fashion which are shown in the artworks of them are as follows. First, the characteristics of Versace dated from southern sensibility are sensualism, expressionism, historicism. 1) Sensualism: tight silhouette, overexposure, glamorous form, brilliant color, fabric showing femininity, gaudy accessaries 2) Expressionism: brilliant print and color, trimmings and accessaries 3) Historicism: form and motifs that are shown in the historical costume Second, the characteristics of Armani succeeded from northern tailoring are purism, functionalism, and multi-culturism. 1) Purism: clean lines, architectural and geometric forms, natural body line, neutral tones, luxurious fabric 2) Functionalism: functional form, neutral tone, natural fabrics 3) Multi-culturism: design and motif inferred from ethnic costume As such. competition between two different groups made it possible that Italian fashion occupies a special place in the international fashion system.

• Journal of The Korean Astronomical Society
• /
• v.47 no.5
• /
• pp.187-193
• /
• 2014

Recent cosmological observations indicate that the reionized universe may have started at around z = 6, where a significant suppression around $Ly{\alpha}$ has been observed from the neutral intergalactic medium. The associated neutral hydrogen column density is expected to exceed $10^{21}cm^{-2}$, where it is very important to use the accurate scattering cross section known as the Kramers-Heisenberg formula that is obtained from the fully quantum mechanical time-dependent second order perturbation theory. We present the Kramers-Heisenberg formula and compare it with the formula introduced in a heuristic way by Peebles (1993) considering the hydrogen atom as a two-level atom, from which we find a deviation by a factor of two in the red wing region far from the line center. Adopting a representative set of cosmological parameters, we compute the Gunn-Peterson optical depths and absorption profiles. Our results are quantitatively compared with previous work by Madau & Rees (2000), who adopted the Peebles approximation in their radiative transfer problems. We find deviations up to 5 per cent in the Gunn-Peterson transmission coefficient for an accelerated expanding universe in the red off-resonance wing part with the rest wavelength ${\Delta}{\lambda}{\sim}10{\AA}$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.2
• /
• pp.85-93
• /
• 2008

In 22.9[kV]-y distribution systems, underground cables are provided with 3-wire loop multiple-point ground in which each coaxial-neutral line of the distribution cable lines(A, B, C phases) is 3-wire common grounded at every connecting section. In the underground cable distribution systems, circulating current flows in the coaxial-neutral lines and its magnitude amounts to about $40{\sim}50[%]$ load currents, even though loads are balanced. This paper presents a new ground method to overcome such a problem and a comprehensive analysis in tows of current capacity of power cables, induced voltage of cable sheath, and electromagnetic interference voltage from power cable lines.