• Title, Summary, Keyword: Gap Analysis

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A Study on Sinewave Air Gap Flux Density of Surface Type Magnet Motor (표면부착형 영구자석 전동기의 정현파 공극자속밀도 연구)

  • Kim, Hyun-Cheol;Kim, Jang-Mok;Kim, Cheul-U
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.9
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    • pp.1571-1576
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    • 2007
  • This report describes the analytical characteristic of sinewave air gap flux density for the brushless AC motor with surface permanent magnet. The analysis of sinewave air gap flux density is the key to expect the performance of back EMF for the design of brushless AC motor. The numerical analysis and FEM analysis are performed to adopt radial and parallel flux magnetization of magnet on the rotor. And it is also executed to vary the magnet arc angle and arc radius for the condition of constant and non constant air gap. This report is focused on the characteristic of sinewave air gap flux density for permanent magnet of surface brushless AC motor. This results also have more reliable data against the previous paper which had the representative numerical analysis of air gap flux density[1][2].

A Study on Heat Flow of Laser-Welded Dissimilar Steel Joints with Gap (틈새가 존재하는 이종강 레이저 용접부의 열유동에 관한연구)

  • Yang, Hae-Sug
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.3
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    • pp.5-15
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    • 2007
  • A welding structures is generally composed of dissimilar steel materials in order to reduce weight cost, and has a gap to fill the welding agent. Also, heat flow analysis should be fulfilled for structure existing of gap to figure out residual stress which is generated after welding. Since mechanical properties of welding structure composed of dissimilar steel is more fragile than mechanical properties of welding structure consisted of same material, heat flow analysis verifying this should be fulfilled as well. Therefore, on this research, heat flow analysis about dissimilar steel weldment consisted of gap existing AISI304 and AISI630 is practiced so that it could be a basic data of research about mechanical properties of gap existing dissimilar steel welding part which is going to be studied later on. During heat flow analysis, heat input model which based on Gaussian profile and using volume heat flux was newly consisted and applied. In addition, for verifying of analysis on this research, gap existing dissimilar steel weldment which had gap of 0.25mm and was welded using Nd-YAG. The welding profile and temperature distribution for weldment during welding was compared to the result which was gotten through heat flow analysis. Both of those results corresponded each other.

Forced Acoustic Response Analysis of an Acoustic Cavity with a Double Air-gap Resonator for Reducing Passenger Compartment Noises (차실 소음 저감을 위한 복층 에어갭 공명기가 설치된 음향 공동의 강제 음향 응답 해석)

  • Kang, Sang-Wook
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.6
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    • pp.163-169
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    • 2005
  • A theoretical formulation on the forced acoustic response of an enclosed cavity having a double air-gap resonator on one of boundary panels of the cavity is developed in the paper. The double gap resonator consists of two air-gaps and two partition sheets as in the author's previous papers. This paper reveals that the double gap resonator reduces the level of a target noise peak by splitting the peak as two small peaks, and that it is more effective when it is designed so that the upper gap thickness is larger than the lower gap thickness under the constraint that the entire gap thickness is fixed as a constant value. Finally, verification experiments show that the theoretical formulation and analysis results are valid by comparing theoretical results with experimental ones.

Measurement of Nursing Service Quality using SERVQUAL Model (SERVQUAL 모델을 이용한 간호 서비스 질 측정)

  • Lim, Ji-Young;Kim, So-In
    • Journal of Korean Academy of Nursing Administration
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    • v.6 no.2
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    • pp.259-279
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    • 2000
  • This study is a descriptive analytic research measuring nursing service quality, using SERVQUAL model, to make fundamental data and strategies for nursing service improvement. Data were collected by self-reported questionnaire from 202 patients and 142 nurses, from June 7 to 14, 1999. The reliability of instrument were adequate(Cronbach ${\alpha}=.94$). SAS program was utilized for statistical analysis of collected data. The results were as follows; 1. There was a gab between patient's expectation and perception on nursing service(Gap B). Gap D was indicated an affecting factor to decide nursing service quality. Gap C was indicated an indirect affecting factor of nursing service quality. Because it was not statistically significant in total item analysis, but in individual item analysis, 7 items were appeared statistically significant. Gap A was not a gap occurrence factor of nursing service quality. 2. Focuses of nursing service quality improvement strategies were; (1) to direct qualitative improvement of nursing service in order to correspondence patient's nursing service expectation. (2) to make nurse's service activity modified because nurse's practice were not reached patient's expectation level. (3) to need internal, external factor analysis affecting nurse's service activity. 3. Nursing service quality was decided by rather environmental inappropriateness provided nursing service than itself. Therefore, to make nursing service quality improvement, it is required to improve nursing service environment. For this, followings are required; (1) to strengthen nurse's education on lower part of nursing service satisfaction and QI activities. (2) to balance demand and supply of nursing personnel. 3) to fix computerized system for reducing other duties weight except nursing care through analysis of nursing activity. (4) to construct rational cooperating system among related departments. 4. The important parts for nursing service quality improvement were indicated as follows: (1) Gap B: 'prompt reaction', 'examination symptom before patient's complaint', 'hearted nursing service reducing patient's dissatisfaction', 'explanation goals of nursing activities', 'having special Knowledge enough', 'maintenance position comfortably', 'management of patient's physical hygiene'. (2) Gap C: 'maintenance physical safety', 'explanation about hospital rules and facilities'. (3) Gap D: 'tender, safe injection and wound care'. Because above items are mostly improved through nurse's attitude change and quality improvement, it is required to establish nursing standardization and to strengthen nurse's clinical education. As the based on above results, followings are suggested; 1. SERVQUAL model is very useful to make strategies for nursing service quality improvement because it indicates multiple factors affecting hap occurrence. 2. At individual items analysis of Gap C, statistically significant 7 items appeared higher nurse's perception level than patient's perception level on nursing service were trouble perception level on nursing service quality improvement. So. it need further research to analysis about these difference occurring factors. 3. At analysis of Gap D, it is indicated that in nursing service performance process, multiple factors lowing nursing service quality were intruded. So it needs further research to analysis what these factors are and how each factors affect on nursing performance process. 4. nursing service quality measurement is changeable according to sample select time or sampled subject's characteristics. So to develope strategy for nursing service quality improvement is based on the results of periodical analysis.

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Finite Element Analysis of the Coiling Process of Hot Bar in coil Box of Mini-Mill (미니밀 코일박스의 권취공정에 대한 유한요소 해석)

  • 이호국;이상로
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.32-39
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    • 1997
  • The coiling station of ISP coil box is an equipment that winds a hot bar rolled at reduction unit into a coil without mandrel. In the coiling process, the roll gap of the bending unit is a significant one of several factors that influence bar coiling. To obtain a good bar-coil, the roll gap must be set appropriately according to the bar thickness. In this study, with 2-dimensional isothermal elastic-plastic finite element method, authors investigated influence of the change of the roll gap on the initial coiling shapes and the formed inner diameters of coils. Based on finite element analysis, authors proposed the appropriate roll gap according to the bar thickness to be able to wind a hot bar. The inner diameters of coils by results of analysis comparatively agreed with coling operation conducted in plant.

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통신서비스 경로상에서의 서비스질의 결정요인에 관한 연구

  • O, Se-Jo;Kim, Seong-Il;Park, Hyeon-Jin
    • Journal of Distribution Research
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    • v.1 no.2
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    • pp.29-52
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    • 1996
  • The objective of this study is to test Parasurman, Zeithaml & Berry(1985)'s service quality gap analysis model, and to confirm reliability and to confirm reliability and validity of the model. The reliability of the model is adopted, but the validity must be retested in the further study. In the results of the gap analysis model, the correlation between consumer expectations and management perceptions of consumer expectations(gap1) was not accepted. The correlation between management perceptions of consumer expectations and service quality specifications(gap2), the correlation between service quality specifications and the service actually delivered(gap3), and the correlation between services delivered and services promised to consumers(gap4) were accepted. To improve domestic telecommunication service quality, practical guides such as standardization of job roles, cooperation among customer-contact persons, communication between managers and employees, evaluation programs for employee's improvement of service quality, appropriate supports for customer-contact persons were suggested. For generalizing the gap model, additional studies under the different contexts and industries will be needed.

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Numerical Investigation of the Flow Pulsation in the Gap connecting with Two Parallel Channels with Different Cross-section Areas (크기가 다른 단면을 가진 평행한 두 채널을 연결하는 협소유로의 맥동유동에 관한 수치해석)

  • Seo, Jeong-Sik;Hong, Seong-Ho;Shin, Jong-Kuen;Choi, Young-Don
    • Proceedings of the KSME Conference
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    • pp.2810-2815
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    • 2008
  • Flow pulsation in the gap connecting with two parallel channels is investigated by RANS and URANS approaches. The two parallel channels are connected by a small channel called for a gap. The parallel channels are designed to have different cross section area with its ratio of 0.5. Computations are conducted using a CFX 11.0 code. The bulk Reynolds number is 60,000. Predicted results are compared with the previous experimental result. Mean velocity profile at the center of gap region are compared with experiments for its validation. Spectral analysis on the lateral velocity in the center of the gap is presented. Auto and cross correlation for the axial-flow velocity pattern are presented. The unsteady structure of the flow pulsation was visualized in the region of the gap in the parallel channel.

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Application of Taguchi Methodology for Optimization of Parameters of CVD Influencing Formation of a Desired Optical Band Gap of Carbon Film

  • Mishra, D.K.;Bejoy, N.;Sharon, Maheshwar.
    • Carbon letters
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    • v.6 no.2
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    • pp.96-100
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    • 2005
  • Taguchi methodology has been applied to get an idea about the parameters related to the chemical vapour deposition technique, which influences the formation of semiconducting carbon thin film of a desired band gap. L9 orthogonal array was used for this purpose. The analysis based on Taguchi methodology suggests that amongst the parameters selected, the temperature of pyrolysis significantly controls the magnitude of band gap (46%). Sintering time has a small influence (30%) on the band gap formation and other factors have almost no influence on the band gap formation. Moreover this analysis suggests that lower temperature of pyrolysis (${\leq}$ $750^{\circ}C$) and lower time of sintering (${\leq}$ 1 h) should be preferred to get carbon thin film with the desired band gap of 1.2eV.

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A Design Optimization of Asymmetric Air-gap Structure for Small 3-phase Permanent Magnet SPM BLDC Motor

  • Kam, Seung-Han;Jung, Tae-Uk
    • Journal of Magnetics
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    • v.20 no.1
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    • pp.91-96
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    • 2015
  • As many researchers are relentlessly trying to improve the power generation schemes from the power grid, to meet the constantly increasing electricity demand. In this paper, the results of a finite element analysis are carried out to study on a design optimization of an asymmetric air-gap structure in 3-phase Permanent Magnet Brushless DC Motors. To achieve a high efficiency for a 3-phase PM BLDC motor, the asymmetric air-gap structure is proposed considering the rotation direction of a motor. Generally, a single-phase BLDC motor is applied asymmetric air-gap structure for starting. This is because the asymmetric air-gap structure causes reluctance variation so the motor can utilize reluctance torque toward a rotation direction. In this paper, the asymmetric air-gap is applied to 3-phase BLDC SPM motor so it utilizes reluctance torque with alignment torque. A proposed model is designed by 2-D FE analysis and the results are verified by experimental test.

Numerical Investigation of the Flow Pulsation in the Gap connecting with Two Parallel Rectangular Channels with Different Cross-section Areas (크기가 다른 단면을 가진 평행한 사각 유로를 연결하는 협소유로의 맥동유동에 관한 수치해석)

  • Seo, Jeong-Sik;Shin, Jong-Kuen;Choi, Young-Don
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.7
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    • pp.512-519
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    • 2009
  • Flow pulsation in the gap connecting with two parallel channels is investigated by RANS and URANS approaches. The two parallel channels are connected by a small channel called for a gap. The parallel channels are designed to have different cross section area with its ratio of 0.5. Computations are conducted using a CFX 11.0 code. The bulk Reynolds number is 60,000. Predicted results are compared with the previous experimental data. Mean velocity profile at the center of gap region are compared with experiments for its validation. Spectral analysis on the lateral velocity in the center of the gap was performed. Auto correlation for the axial-flow velocity pattern was presented. The unsteady structure of the flow pulsation was visualized in the region of the gap in the parallel channel.