• Journal of Electrical Engineering and Technology
• /
• 제9권3호
• /
• pp.882-887
• /
• 2014

In this paper, the water cooling method among the forced coolant cooling methods is considered to be applied to the 110kW-class IPMSM for railway vehicles. First, basic thermal property analysis of the IPMSM is conducted using the three-dimensional thermal equivalent network method. Then, based on the results of the basic thermal property analysis, some design requirements for the water cooling jacket are deduced and a basic design of the water cooling jacket is carried out. Finally, thermal equivalent circuit of the water cooling jacket is attached to the IPMSM's 3D thermal equivalent network and then, the basic thermal and effectiveness analysis are conducted for the case of applying the water cooling jacket to the IPMSM. In the future, the thermal variation trends inside the IPMSM by the application of the water cooling jacket is expected to be quickly and easily predicted even at the design step of the railway traction motor.

• 대한수학회논문집
• /
• 제25권3호
• /
• pp.477-484
• /
• 2010

In this paper, we introduce a new property (*) of a topological space and prove that if X satisfies one of the following conditions (1) and (2), then compactness, countable compactness and sequential compactness are equivalent in X; (1) Each countably compact subspace of X with (*) is a sequential or AP space. (2) X is a sequential or AP space with (*).

• Nuclear Engineering and Technology
• /
• 제38권7호
• /
• pp.689-696
• /
• 2006

For a perforated plate, it is challenging to develop a finite element model due to the necessity of the fine meshing of the plate, especially if it is submerged in fluid. This necessitates the use of a solid plate with equivalent material properties. Unfortunately, the effective elastic constants suggested by the ASME code are deemed not valid for a modal analysis. Therefore, in this study the equivalent material properties of a perforated plate are suggested by performing several finite element analyses with respect to the ligament efficiencies.

• 대한수학회지
• /
• 제56권5호
• /
• pp.1387-1401
• /
• 2019

Consider a finite measure space (${\Omega}$, ${\Sigma}$, ${\mu}$) and a Banach space $X({\mu})$ consisting of (equivalence classes of) real measurable functions defined on ${\Omega}$ such that $f{\chi}_A{\in}X({\mu})$ and ${\parallel}f{\chi}_A{\parallel}{\leq}{\parallel}f{\parallel}$, ${\forall}f{\in}({\mu})$, $A{\in}{\Sigma}$. We prove that if it satisfies the subsequence property, then it is an ideal of measurable functions and has an equivalent norm under which it is a Banach function space. As an application we characterize norms that are equivalent to a Banach function space norm.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.1218-1223
• /
• 2007

In this study, we experimentally investigate the equivalent ring theory for a slightly asymmetric ring. The slightly asymmetric ring has mode pair and frequency pair due to the small asymmetry and this mode pair generates beat in vibration and sound. In this paper, a slightly asymmetric ring is modeled as the equivalent ring, i.e., the assemblage of a symmetric ring and imperfect point masses. The equivalent ring has the same mode pair condition as that of the original asymmetric ring. Effect of the additional mass attachment is investigated by the equivalent ring theory and the result is compared with those of the measurement and the finite element analysis. It is confirmed that the original ring and the equivalent ring show the same change in frequency and mode under the various additional imperfection mass conditions. The equivalent ring theory explains how the asymmetric elements influence the mode characteristics and provides useful information to tune the beat property.

• Journal of Electrical Engineering and Technology
• /
• 제11권2호
• /
• pp.463-469
• /
• 2016

In this paper, the use of a dual composite right/left-handed coplanar waveguide (CPW) transmission line is proposed for the design of a band rejection filter. The notch property of the filter is achieved by combining the convex signal line with the shorted concave meander line, and the equivalent circuit model is extracted from the geometry of the unit cell for organizing the band rejection property. Then the equivalent parameters of the unit cell are analyzed to identify those behaviors. And the dispersion characteristics and energy distributions are simulated. In the end, the band rejection filter is manufactured by cascading two proposed unit cells. We show that the measurement result for the resonant frequency demonstrates good agreement with the simulation result and the band rejection filter provides a rejection performance of 17.5 dB at the stopband frequency ranging from 869 MHz to 894 MHz.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.452-453
• /
• 2007

In this work, enhanced simulation is proposed by using impedance spectroscopy. The impedance spectroscopy is one of the popular methods to measure the electrical property of Organic Light Emitting Diodes. The results show that the equivalent circuit needs a inductance element linked by serial connection and the element of resistance is more important role to decide the electrical property.

• 충청수학회지
• /
• 제31권1호
• /
• pp.167-175
• /
• 2018

In this paper we show that two notions of the average shadowing property and the hyperbolicity are equivalent in linear dynamical systems on the vector space ${\mathbb{C}}^n$.

• 대한수학회지
• /
• 제58권1호
• /
• pp.207-218
• /
• 2021

In this paper, the notion of two-sided limit shadowing property is considered for a positively expansive open map. More precisely, let f be a positively expansive open map of a compact metric space X. It is proved that if f is topologically mixing, then it has the two-sided limit shadowing property. As a corollary, we have that if X is connected, then the notions of the two-sided limit shadowing property and the average-shadowing property are equivalent.

• 한국음향학회지
• /
• 제31권8호
• /
• pp.561-568
• /
• 2012

본 연구는 등가 종 모델을 이용하여 한국종의 맥놀이 주기를 조절하는 방법을 제시한다. 한국종이 갖고 있는 미세한 비대칭성은 하나의 원주 모드를 미세한 주파수의 차이를 갖는 모드 쌍으로 분리시키는데, 이 모드 쌍의 상호간섭에 의해서 진동과 음향의 맥놀이가 발생한다. 등가 종은 축대칭 종에 등가 집중질량을 부착시킨 미소 비대칭 구조물로, 실제 종의 모드 쌍과 동일한 모드 특성을 갖는다. 등가 종 모델은 회전 쉘 이론을 근거로, 유한요소해석을 통해서 구성된다. 맥놀이 특성을 변화시키기 위하여 국부적으로 요소 두께를 감소시킬 때, 등가 종을 이용하여 맥놀이 주기를 예측한다. 예측 결과는 시험 종에 대한 실험을 통해 그 타당성을 확인한다. 본 방법은 대형 종의 맥놀이 주기 조절에 소요되는 시간을 크게 줄일 수 있을 것이다.