• Communications of the Korean Mathematical Society
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• v.24 no.4
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• pp.561-564
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• 2009

A holomorphic function space in the unit disc D satisfying $\int_D|f'(z)|^p(1-|z|^2)^{p-1}dA(z)$<$\infty$ is quite close to $H^p$. The problems on the existence of the radial limits are considered for this space. It is proved that the situation for p > 2 is totally different from the situation for p $\leq$ 2.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.10
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• pp.959-967
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• 2012

The theory for a new electromagnetically biased diskless combined radial and axial magnetic bearing is developed. A typical magnetic bearing system is composed of two radial magnetic bearings and an axial magnetic bearing. The axial magnetic bearing with a large axial disk usually limits rotor dynamic performance and makes assembling and disassembling difficult for maintenance work. This paper proposes a novel electromagnet biased integrated radial-axial magnetic bearing without axial disk. This integrated magnetic bearing uses two axial coils to provide the bias flux to the radial and axial air gaps of the combined bearing. The axial magnetic bearing unit in this combined magnetic bearing utilizes reluctance forces developed in the non-uniform air gaps such that the axial disk can be removed from the bearing unit. The 4-pole homopolar type radial magnetic bearing unit is also designed and analyzed. Three dimensional finite element model for the bearing is also developed and analyzed to illustrate the diskless combined magnetic bearing.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.274-280
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• 2023

The Fix-to-Fix Navigation is the technique for aircraft pilots to find out estimated Heading when crossing from present fix to other fix to want to go in the air. Because this is based on the Rule of Thumb method from one's experience, it could not find out exact estimated Heading. Furthermore if the pilot nears going fix, Bearing Pointer and Course Indicator of HSI are too close to use this technique, that makes the pilot lost in the air. In this paper, We take Limits of Trigonometric Functions into the Fix-to-Fix Navigation to overcome these disadvantages. This study introduces two solutions using Limits of Trigonometric Functions when doing Fix-to-Fix Navigation and analyzes the error of this solutions.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.423-426
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• 2007

Pohang Wind Energy Research Center (PoWER-C) is developing a 3 MW Radial Flux Permanent Magnet (RFPM) Synchronous Generator for offshore Wind Energy Converter (WEC). The rotor rpm is 15.7 and the gear ratio is set to be 92.93. The nominal generator rpm at the rated load is about 1459. To reduce the switching loss in the power electronics, the maximum frequency is limited to 100 Hz. This requirement limits the number of pole to six or eight. Permanent magnet excitation is assumed for higher energy yield and higher efficiency. In this report, the requirements and the first efforts for the physics design are described.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.620-625
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• 2007

According to 'Metropolitan Traffic Network Plan' announced in 2001, radial railways which connect Seoul with satellite cities around Seoul appear gradually. And followed by this, social demand for circular metropolitan railways that can connect the radial railways horizontally is increasing. But existing plans about circular metropolitan railways has limits to propose only passing cities of the railways. If there is no detailed guideline for circular metropolitan railways, the each railway for circular line will be constructed individually and then it will be not effective circular railways totally. Additionally that railway project will be easily interrupted by popular complaints. Therefore "The basic plan for circular metropolitan railways" is needful to guide a right direction for circular metropolitan railways. In this paper, rough track diagram of 'node' station for circular metropolitan railways is proposed. It is essential part of the basic plan. If the track diagram of a node is publicized in advance and individually lines of circular metropolitan railways is enforced to followed it, all lines will has rich circular functionality. Finally, effective circular metropolitan railways can be built.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.451-457
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• 2011

The function f(z) = $e^{p(z)}$ where p(z) is a polynomial of degree n has 2n Julia lines. Julia lines of $e^{p(z)}$ divide the complex plane into 2n equal sectors with the same vertex at the origin. In each sector, $e^{p(z)}$ has radial limits of 0 or innity. Main results of the paper are concerned with maximum curves of $e^{p(z)}$. We deal with some properties of maximum curves of $e^{p(z)}$ and we give some examples of the maximum curves of functions of the form $e^{p(z)}$.

• Journal of the Korean Ceramic Society
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• v.23 no.5
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• pp.47-54
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• 1986

The structures of crystalline vitreous and liquid $SiO_2$ were Monte carlo simulated employing the potential energy function comprising Lennard-Jones 2-body and Axilrod-Teller 3-body potentials. Although the Si-O-Si angular distribution functions obtained in the simulation appear to be higher than the experimental results the other simulation results including SiO, O-O and Si-Si radial distribution functions and O-Si-O anglular distribution functions agree well with experimental data within acceptable limits. Themost important outcome in this study is that various $SiO_2$forms were successfully reproduced with the same potential energy function.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.286-287
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• 2015

Currently, Studies on improving the reliability of power supply is becoming an important issue because of the increase in demand of the electric power system. Therefore necessity of automation in distribution system is increasing day by day. However, a measured voltage data from FRTU of distribution automation system is incorrect because of installation space limits. Therefore there is a need of system analysis method by considering the characteristics of the distribution system. For a distribution system, applying the power flow method of transmission system has some problems, as distribution is radial system and it has unbalanced load. Therefore power flow by considering the characteristics of the distribution system have been studied. Existing power flow analysis of the distribution system has different methods like direct analysis method, backward/forward sweep method, modified method of newton raphson etc. In this paper, an improved power flow analysis method based on backward/forward sweep method is proposed in order to efficiently operate the distribution automation system. The proposed method of power flow has been verified through the result of case study.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.3-9
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• 1996

In this study, comparison of theoretical solutions with experimental results is examined through fracture conditions for the case of float glasses subjected static loading. The range of fracture generation limits and critical penetration energies are solved according to the impactor mass under the high velocity, and analytical method of fracture strength and penetration strength are presented. Also, fracture patterns are investigated according to impact velocities. The results obtained from this study are as follows ; 1) Radial cracks are generated from the loading point regardless of plate thickness in the case of the plate subjected to the static loading. In the case of high-speed impact, dimensions of ring cracks become to smaller and length of radial cracks becomes shorter with the rapidity of impact velocity. 2) Kinetic change volume of collision after/before is constant regardless of velocities over the range of critical penetration velocity. 3) Although the same impact energy is working, the critical penetration energy is increased with the shorter of impactor mass. 4) Although the same impact energy is working, the penetration fracture of lighter Impactor mass is generated more than that of heavier impactor mass, and the impulse of lighter impacter mass appear more than that of heavier impactor mass. Therefore, the penetration fracture in the case of greater impulse is generated earlier regardless of the of the dimensions of Impact loading.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.703-711
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• 2003

We have theoretically studied the nonadiabatic transitions among the five lower states with the Ω=$1_u$ symmetry ($1_u^{(1)} to 1_u^{(5)}$) in the photodissociation of Cl₂, Br₂, and I₂by using the spin-orbit configuration interaction (SOCI) method and the semiclassical time-dependent coupled Schrodinger equations. From the configuration analyses of the SOCI wavefunctions, we found that the nonadiabatic transition between $1_u^{(2)}$ and $1_u^{(1)}$ is a noncrossing type, while that between $1_u^{(3)}$ and $1_u^{(4)}$ is a crossing type for all the molecules. The behavior of the radial derivative coupling element between $1_u^{(1)}$ and $1_u^{(2)}$ and that between $1_u^{(3)}$ and $1_u^{(4)}$ is analyzed in detail. In Cl₂, nonadiabatic transitions can take place even between the states correlating to different dissociation limits, while in Br₂ and I₂, with the usual photon energies e.g. less than 20 eV, nonadiabatic transitions occur only between the states correlating to the same dissociation limits, reflecting the different magnitudes of the spin-orbit interactions.