• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.609-617
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• 2016

Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Look-up table (LUT). The experiment shows the validity of algorithm.

• 한국소음진동공학회논문집
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• 제27권1호
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• pp.20-27
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• 2017

This study investigated the problems in current practice of drive-train resonance analysis procedure and suggested solutions. The first problem is the resonance occurrence at the un-identified resonance point by the current practice, as for a solution the force spectrum analysis for each critical force transmitting component was suggested. The second one is the inaccurate estimation of potential resonance point in eigenfrequency analysis because of the non-consideration about the eigenfrequency dependency on rotor-speed, the fine linearization at each rotor speed point all over operational range was proposed to account for the affection. Lastly the insufficient time for resonance activation under run-up simulation condition was recognized as a problem in resonance load increasing analysis, as an alternative, steady state condition was suggested to estimate the maximum load increasing level.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.479-483
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• 1997

In general, motor parameters can be divided into mechanical/electrical parameters and harmonic parameters. Mechanical/electrical parameters identification of motor have been studying systematically for a long time. But, systematical study on harmonic parameters analysis for efficient motor drive system are very poor. The goal of this paper is to propose analyzing method of harmonic parameters for motor drive system with various experimental graphic screens and numerical results and to develope harmonic parameters analyzer. A developed analyzer is made up 586-PC and DSP (digital signal processor) board, motor drive system, power and harmonic parameters analyzing software for windows. Harmonic parameters are analyzed using correlation signal processing techniques based on the correlation between voltage and current waveforms. Analysis results are visualized by 3-D current coordinates, and it is compared and evaluated with conventional time/frequency domain. To verify the validity of the proposed system, 1/4HP capacitor run type single phase induction motor and thyristor speed controller is used for analyzing. Harmonic parameters of motor drive system is analyzed and verified, with varying fire angle of thyristor speed controller, and the proposed approach is to confirm validity.

• 한국콘텐츠학회논문지
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• 제8권5호
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• pp.134-144
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• 2008

도시환경디자인에서의 간판의 역할은 상점을 알려주는 기능적인 면도 있지만 그 지역의 전반적인 분위기를 조성해주는 심미적인 면이 크다고 볼 수 있다. 간판이 도시환경에 미치는 영향은 크며 도시의 이미지를 결정한다. 도시환경의 구체적인 목표는 인간의 쾌적성을 확보하는 것이며 인간은 아름답고 쾌적한 도시환경에서 보다 질 높은 삶을 살기를 갈망하며 추구한다. 그러나 현재 서울을 비롯한 우리나라 도시는 난립된 광고물과 간판이 주변 환경과 조화를 이루지 못하고 있는 실정이며 도시환경의 질을 떨어뜨리고 시민들에게 시각적 불쾌감을 주는 공해요인으로 대두되고 있다. 이러한 문제점을 해결하고자 서울시와 동경도의 간판관리를 비교분석하여 서울시 간판관리의 문제점을 모색하여 보다 체계적으로 간판관리가 될 수 있도록 하고 간판 개선 방안을 모색하기 위한 기초 자료가 되도록 한다.

• 분석과학
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• 제28권5호
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• pp.309-316
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• 2015

본 연구에서는 ICP-MS의 혈장 중 극미량의 납 분석법을 검증하기 위하여 Class 1,000 이내의 환경조건을 확보한 후 특이성, 일내 및 일간 정확도, 정밀도, 검정곡선 등을 확인하였다. 청정실의 부유 분진량을 측정한 결과, 0.3 µm 크기는 0.3~62개, 0.5 µm 크기는 0.0~28.3 개로 총 부유분진량이 최대 90.3개로 요구 환경에 부합하였다. 우태아 혈청 공시료로 조제한 시료의 MDL (Method detection limit)은 1.77 ng/L이고, LOQ (Limit of quantification)값은 5.55 ng/L 이었다. 검정곡선은 y=1.09×10⁻³ x+4.88×10⁻²이었고, 상관계수 r=0.9999이었다. 분석법 확립을 위한 특이성, 일내 및 일간 정확성, 정밀성, 그리고 검정곡선을 확인한 결과 50 ng/L 이상에서 분석법 확인 기준에 적합하였다. 이를 토대로 분석한 일반인의 혈장 중 납 농도 평균은 55.4 ng/L 이었으며, 현직 근로자는 440 ng/L 이었고, 퇴직 근로자는 132 ng/L 이었다.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.186-196
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• 2017

In order to resolve the trimming difficulty in rotor CFD calculations, a high-efficiency and improved "delta trim method" is established to compute the blade control settings that are necessary to identify the blade motion. In this method, a simplified model which combines the blade element theory and different inflow models is employed to calculate the control settings according to the target aerodynamic forces, then it is coupled into a CFD solver with unsteady Navier-Stokes equations by the delta methodology, which makes the control settings and aerodynamics calculated and updated in the meantime at every trim cycle. Different from the previous work, the current research combines the inflow model based on prescribed wake theory. Using the method established, the control settings and aerodynamic characteristics of Helishape 7A, AH-1G and Caradonna-Tung rotors are calculated. The influence of different inflow models on trimming calculations is analyzed and the computational efficiency of the current "delta trim method" is compared with that of the "CFD-based trim method". Furthermore, for the sake of improving the calculation efficiency, a novel acceleration factor method is introduced to accelerate the trimming process. From the numerical cases, it is demonstrated that the current "delta trim method" has higher computational efficiency than "CFD-based trim method" in both hover and forward flight, and up to 70% of the amount of calculation can be saved by current "delta trim method" which turns out to be satisfactory for engineering applications. In addition, the proposed acceleration factor shows a good ability to accelerate the trim procedure, and the prescribed wake inflow model is always of better stability than other simple inflow models whether the acceleration factor is utilized in trimming calculations.

• Ocean Systems Engineering
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• 제6권1호
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• pp.23-60
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• 2016

The major objective of this study was to develop further understanding of 3D nearshore hydrodynamics under a variety of wave and tidal forcing conditions. The main tool used was a comprehensive 3D numerical model - combining the flow module of Delft3D with the WAVE solver of XBeach - of nearshore hydro- and morphodynamics that can simulate flow, sediment transport, and morphological evolution. Surf-swash zone hydrodynamics were modeled using the 3D Navier-Stokes equations, combined with various turbulence models (${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES). Sediment transport and resulting foreshore profile changes were approximated using different sediment transport relations that consider both bed- and suspended-load transport of non-cohesive sediments. The numerical set-up was tested against field data, with good agreement found. Different numerical experiments under a range of bed characteristics and incident wave and tidal conditions were run to test the model's capability to reproduce 3D flow, wave propagation, sediment transport and morphodynamics in the nearshore at the field scale. The results were interpreted according to existing understanding of surf and swash zone processes. Our numerical experiments confirm that the angle between the crest line of the approaching wave and the shoreline defines the direction and strength of the longshore current, while the longshore current velocity varies across the nearshore zone. The model simulates the undertow, hydraulic cell and rip-current patterns generated by radiation stresses and longshore variability in wave heights. Numerical results show that a non-uniform seabed is crucial for generation of rip currents in the nearshore (when bed slope is uniform, rips are not generated). Increasing the wave height increases the peaks of eddy viscosity and TKE (turbulent kinetic energy), while increasing the tidal amplitude reduces these peaks. Wave and tide interaction has most striking effects on the foreshore profile with the formation of the intertidal bar. High values of eddy viscosity, TKE and wave set-up are spread offshore for coarser grain sizes. Beach profile steepness modifies the nearshore circulation pattern, significantly enhancing the vertical component of the flow. The local recirculation within the longshore current in the inshore region causes a transient offshore shift and strengthening of the longshore current. Overall, the analysis shows that, with reasonable hypotheses, it is possible to simulate the nearshore hydrodynamics subjected to oceanic forcing, consistent with existing understanding of this area. Part II of this work presents 3D nearshore morphodynamics induced by the tides and waves.

• 한국관광식음료학회지:관광식음료경영연구
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• 제10권
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• pp.187-202
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• 1999

We desperately recognize from the economic situation in IMF crisis that only competive goods and serviced. It is anticipated that this difficult situation will probably be continued till 1999. Therefore, it is necessary to think over real aspects of eating=outdoors in IMF period and to provide an opportunity to confront with this crisis. Analysis a recent tendency of domestic eating-outdoors business, there appears, first of all, dual types of eating-outdoors; the one is a sort of 'Cost Sale', which provides some special menu with lowest prices, and the other is a type of 'Family Restaurant', which regards the atmosphere of the place as one of the most essential elements. Both types are getting more popular today. As the result, neither of the alternative cannot recover the current Depression. It is natural that no other conditions can compete with good tastes, fancy atmosphere, and good prices. As a matter of fact, however, it is quite difficult to run this type of bussiness adjusted the above whole conditions. Therefore owners of eating-house must decide to run either ' Cost Sale' or 'Family Restaurant' first and investigate some problems and conditions accordingly. In ane way, the owner intensively visits to some eating houses which is similar style in size and management to that of his style in size and management to that of his and look over what is good and what is bad Right after this investigation, it is efficient for he or she to improve his or her business style in size and management in a short period. It is helpful to check some complements; improvement of signboards, cleaning up of the interior, selecting suitable menu, adjusted prices, tastes, and service quality etc. Although eating-outdoors business is hard hit by IMF, We hope that it would rapidly be brisk in 2000, becaused by that time the basis of each industry would be high qualified, and rich technology would be accumulated.

• 산업경영시스템학회지
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• 제33권3호
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• pp.146-153
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• 2010

When the production run is short and process parameters change frequently, it is difficult to monitor the process using traditional control charts. In such a case, the coefficient of variation (CV) is very useful for monitoring the process variability. The CV control chart is an effective tool to control the mean and variability of process simultaneously. The CV control chart, however, is not sensitive at small shifts in the magnitude of CV. The CV-EWMA(exponentially weighted moving average) control chart which was developed recently is effective in detecting a small shifts of CV. Since the CV-EWMA control chart scheme can be viewed as a weighted average of all past and current CV values, it is very sensitive to small change of mean and variability of the process. In this paper, we propose an FIR(Fast initial response) CV-EWMA control chart to improve the sensitivity of a CV-EWMA scheme at process start-up or out-of-control process. Moreover, we suggest the values of design parameters and show the results of the performance study of FIR CV-EWMA control chart by the use of average run length(ARL). Also, we compared the performance of FIR CV-EWMA control chart with that of the CV-EWMA control chart and we found that the CV-EWMA control chart gives longer in-control ARL and much shorter out-of-control ARL.

• 한국멀티미디어학회논문지
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• 제13권1호
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• pp.1-9
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• 2010

모바일 통신의 발전으로 데스크탑과 같이 위치가 고정적인 시스템 외에도 이동이 편리한 휴대폰 등의 모바일 컴퓨팅시스템이 많이 이용되고 있다. 모바일 단말기의 컴퓨팅 성능이 발전하고 있지만, 많은 계산이나 처리를 요구하는 소프트웨어를 휴대폰 같은 모바일 단말기에서 이용하기는 힘들다. 이 같은 단점을 해소하기 위해 모바일 클러스터 컴퓨팅을 활용하기로 하고, 본 연구에서는 기존 모바일 컴퓨팅 시스템을 분석하였지만 기존의 모바일 클러스터 컴퓨팅 연구들에서는 구현보다는 시스템 구조 제안에 머물고 있거나, 실제 휴대폰 등의 단말기로 구현한 예가 없는 등, 현실에서 활용하기에는 무리가 있는 실정이다. 이에 본 논문에서는 기존의 JPVM 클러스터 시스템에 휴대폰이 참여하도록 하고 클러스터 시스템에서 대용량 소프트웨어를 처리하여 휴대폰에서 그 결과를 볼 수 있도록 하였다. JPVM 클러스터에 참여한 휴대폰 상에서는 병렬 응용의 실행과 종료뿐만 아니라 그 실행 결과도 원하는 형태로 볼 수 있다. 구현된 시스템은 휴대폰이 클러스터 시스템에 참여할 수 있다는 측면에서 Mobile-JPVM이라고 할 수 있으며, 성능평가를 통해 Mobile-JPVM이 대용량 소프트웨어를 실행시키는데 문제가 없음을 확인하였다.