• 소음진동
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• 제8권5호
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• pp.862-869
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• 1998

The interior noise generated by the windshield wiper system including a wiper motor, the motor mountings and linkages is considered as a structure-borne noise. The structureborne noise is closely related with the system vibration which was transmitted into interior cabin through the car body. In this study, the frequency characteristics of vibration in the wiper motor system were first identified through the frequency analysis. Then effects of the wiper motor mountings and linkages on the vehicle interior noise were studied through in-vehicle measurements. Finally a possibility of noise reduction at a certain frequency was revealed from the study.

• 품질경영학회지
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• 제22권4호
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• pp.79-101
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• 1994

In modern manufacturing, a product consists of many components created by different processes. Variations in the individual component dimensions and in the processes may result in unacceptable final assemblies. Thus, engineers have increased pressure to properly set tolerance specifications for individual components and to control manufacturing processes. When a proper variation stack-up analysis is not performed for all of the components in a functional system, all component parts can be within specifications, but the final assembly may not be functional. Thus, in order to improve the performance of the final assembly, a proper variation stack-up analysis is essential for specifying dimensional tolerances and process control. This research provides a detailed case example of the use of variation stack-up analysis using a Monte Carlo simulation method to improve the defect rate of a complex process, which is the commutator brush track undercut process of an armature assembly of a small motor. Variations in individual component dimensions and process mean shifts cause high defect rate, Since some dimensional characteristics have non-normal distributions and the stack-up function is non-linear, the Monte Carlo simulation method is used.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.696-697
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• 2015

In this paper, the shape of the slit to provide a view of the sensor in such a manner as to encode the rotor position information using a single sensor for studies of economic rotor position and speed detection method for electric motor drive has a special electronic commutator bar-and proposes a robust encoder can produce a rotor position information for each of the woman, and reads out the location information by using the position detection method of the proposed new method compared to traditional DSP Capture function of incremental encoder that its validity was verified through experiments.

• Korean Journal of Mathematics
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• 제5권2호
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• pp.177-183
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• 1997

Let ${\sigma}(X,x_0,G)$ be the fundamental group of a transformation group (X,G). Let $R({\varphi},{\psi})$) be the generalized Reidemeister number for an endomorphism $({\varphi},{\psi}):(X,G){\rightarrow}(X,G)$. In this paper, our main results are as follows ; we prove some sufficient conditions for $R({\varphi},{\psi})$ to be the cardinality of $Coker(1-({\varphi},{\psi})_{\bar{\sigma}})$, where 1 is the identity isomorphism and $({\varphi},{\psi})_{\bar{\sigma}}$ is the endomorphism of ${\bar{\sigma}}(X,x_0,G)$, the quotient group of ${\sigma}(X,x_0,G)$ by the commutator subgroup $C({\sigma}(X,x_0,G))$, induced by (${\varphi},{\psi}$). In particular, we prove $R({\varphi},{\psi})={\mid}Coker(1-({\varphi},{\psi})_{\bar{\sigma}}){\mid}$, provided that (${\varphi},{\psi}$) is eventually commutative.

• 대한수학회지
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• 제49권1호
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• pp.139-151
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• 2012

In the previous paper, we gave a characterization of backward shift invariant subspaces of the Hardy space over the bidisk on which [${S_z}^n$, $S_w^*$] = 0 for a positive integer n ${\geq}$ 2. In this case, it holds that ${S_z}^n=cI$ for some $c{\in}\mathbb{C}$. In this paper, it is proved that if [$S_{\varphi}$, $S_w^*$] = 0 and ${\varphi}{\in}H^{\infty}({\Gamma}_z)$, then $S_{\varphi}=cI$ for some $c{\in}\mathbb{C}$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2024-2026
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• 1998

Many power plants built 20-30 years ago are facing problems associated with the excitation system used for controlling generator output voltage. After years of reliable operation, generation is experiencing increased down time due to maintenance associated with the exciting excitation equipment. Reliability of the excitation system has become an issue, especially where many of these generation plants may be critical to the internal processes used for manufacturing. Wear out mechanisms such as those associated with the wire wound rheostat the electromechanical voltage regulator, insulation failures of the rotating exciter and commutator deterioration have become real problems typical of many older installations. These are some of the issues that are affecting system reliability for older power plants. This paper will address typical problems associated with the old excitation systems and the justification for a replacement static excitation system used in many Paper Mills.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.39-41
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• 2005

In this paper, a study on the controller for high speed PMSM (Permanent Magnet Synchro-nous Motor) is described. PMSM can be driven over 50,000 rpm because it has no brush and commutator structure. It also has less EMI noise and easy cooling structure compare to the other motors. The controller was designed to have a capability to drive 20kw, 42,000rpm high speed motor system. A senseless vector control method was studied based on d-q conversion theory to have a high driving efficiency. The control board was designed using TMS320C33 and the performance was verified by experimental results on driving the inverter and motor system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.327-329
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• 2000

This paper present the characteristic improvements of one-coil coin type vibration Motor. Rotor is consist of coreless coil and 4 segment commutator. Magnet is 4 pole, z direction magnetized. This one-coil coin type vibration motor has simple mechanical structure and good efficiency. So production cost is lower than other having 2 or more coils coin type motor but it has the weak points. That is small vibration magnitude and dead zone. Modifying the shape of rotor, vibration magnitude is increased. To avoid the dead zone we attached more magnetic body on rotor. As result we show the optimal position of magnetic body.

• 전기학회논문지
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• 제64권11호
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• pp.1639-1644
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• 2015

Auxiliary air compressor(ACM) applied to railroad cars is a device which controls amount of compressed air in order that pantographs can be mounted correctly on the roof of an electric train. Existing ACMs consist of dc motors and brushes wear out due to friction with a commutator. Therefore, continuous maintenance is required. However, three phase BLDC motors have higher power density compared to dc motors and the machine maintenance is not needed because electric commutation is possible. The three phase generally uses hall sensors to get position information and this enables the accurate control. This paper suggests an algorithm that compensates the errors occurred when the hall sensors have a breakdown for stable operation.

• 대한수학회지
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• 제44권4호
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• pp.809-822
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• 2007

Certain weak type endpoint estimates are established for maximal commutators generated by $Calder\acute{o}n-Zygmund$ operators and $Osc_{exp}L^{\gamma}({\mu})$ functions for ${\gamma}{\ge}1$ under the condition that the underlying measure only satisfies some growth condition, where the kernels of $Calder\acute{o}n-Zygmund$ operators only satisfy the standard size condition and some $H\ddot{o}rmander$ type regularity condition, and $Osc_{exp}L^{\gamma}({\mu})$ are the spaces of Orlicz type satisfying that $Osc_{exp}L^{\gamma}({\mu})$ = RBMO(${\mu}$) if ${\gamma}$ = 1 and $Osc_{exp}L^{\gamma}({\mu}){\subset}RBMO({\mu})$ if ${\gamma}$ > 1.