• 한국안전학회지
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• 제18권1호
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• pp.44-49
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• 2003

Permanent magnet synchronous motor(PMSM) is widely used in many applications such as an electric vehicle. compressor drives of air conditioner and machine tool spindle drives. PMSM drive system have become a popular choice in various application, due to their excellent power to weight ratio. This paper is proposed maximum torque control for field weakening operation of PMSM drive. At low speeds, the reluctance torque is used to maximize the output for a given current level. This is achieved maximum torque per ampere(MTPA) by selecting an optimal value of the direct stator current component. At high speeds, the system reaches a point at which the inverter will not be able to supply the desired voltage. In this case it is necessary to make use of an increased value the direct current component. The proposed control algorithm is applied to PMSM drive system, the operating characteristics controlled by maximum torque control are examined in detail by simulation.

• 대한전기학회논문지:전력기술부문A
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• 제50권6호
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• pp.279-286
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• 2001

A load modeling, micro method, is performed by component load modeling, load composition rate estimation and aggregation of component load model, etc. The load model obtained from this process must be applied to actual load bus to verify it and to get reliable load model. But it is difficult to apply every load bus due to al lot of load buses and complex experiment. This paper proposed the field test method in load bus to verify the load modeling. For appropriate field test, representative load buses are selected by the proposed algorithm considering the composition rate of user category in all load buses. The field tests were performed at selected load buses to obtain load characteristics of bus by time and seasonal without blackout. The results of measurement and analysis are presented in detail.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.243-248
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstructured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.

• 한국소음진동공학회논문집
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• 제16권7호
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• pp.704-711
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• 2006

Vibration test on MAST(multi axial simulation table) system has several advantage over one-axial vibration test that could simulate 6-DOF, 3-axial translation and 3-axial moment, at the same time. Since field vibration motion can be fully represented with 6-DOF, multi-axial vibration test on vehicle component is widely conducted in technical leading companies to make sure its fatigue performance in vibration environment. On the way to fulfill the process, editing technique of obtained field data is key issue to success a reliable vibration testing with MAST system. Since the original signals are not only too large to fulfill it directly, but all of the measured data is not guarantee its convergency on generating its driving files, editing technique of the original signals are highly required to make some events that should meet the equal fatigue damage on the target component In this paper, key technique on editing a field data feasible for MAST system is described based on energy method in vibration fatigue. To explain its technique explicitly, author first introduced a process on field data acquisition of two vehicle component and then, representing events are produced to keep up with the editing strategy about a energy method. In the final chapter, a time information regarding a vibration test on MAST system is derived from the energy data which is critical information to perform a vibration test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.764-769
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• 2006

Vibration test on MAST(multi axial simulation table) system has several advantage over one-axial vibration test that could simulate 6-DOF, 3-axial translation and 3-axial moment, at the same time. Since field vibration motion can be fully represented with 6-DOF, multi-axial vibration test on vehicle component is widely conducted in technical leading companies to make sure its fatigue performance in vibration environment. On the way to fulfill the process, editing technique of obtained field data is key issue to success a reliable vibration testing with MAST system. Since the original signals are not only too large to fulfill it directly, but all of the measured data is not guarantee its convergency on generating its driving files, editing technique of the original signals are highly required to make some events that should meet the equal fatigue damage on the target component In this paper, key technique on editing a field data feasible for MAST system is described based on energy method in vibration fatigue. To explain its technique explicitly, author first introduced a process on field data acquisition of two vehicle component and then, representing events are produced to keep up with the editing strategy about a energy method. In the final chapter, a time information regarding a vibration test on MAST system is derived from the energy data which is critical information to perform a vibration test.

• 천문학회보
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• 제37권2호
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• pp.116.1-116.1
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• 2012

When an interplanetary (IP) shock passes over the Earth's magnetosphere, the geosynchronous magnetic field strength near the noon is always enhanced, while the geosynchronous magnetic field near the midnight decreases or increases. In order to understand what determines the positive or negative magnetic field response at nightside geosynchronous orbit to sudden increases in the solar wind dynamic pressure, we have examined 120 IP shock-associated sudden commencements (SC) using magnetic field data from the GOES spacecraft near the midnight (MLT = 2200~0200) and found the following magnetic field perturbation characteristics. (1) There is a strong seasonal dependence of geosynchronous magnetic field perturbations during the passage of IP shocks. That is, the SC-associated geosynchronous magnetic field near the midnight increases (a positive response) in summer and decreases (a negative response) in winter. (2) These field perturbations are dominated by the radial magnetic field component rather than the north-south magnetic field component at nightside geosynchronous orbit. (3) The magnetic elevation angles corresponding to positive and negative responses decrease and increase, respectively. These field perturbation properties can be explained by the location of the cross-tail current enhancement during SC interval with respect to geosynchronous spacecraft position.

• 한국도로학회논문집
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• 제16권4호
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• pp.21-33
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• 2014

PURPOSES: The purpose of this study was to break away from the workforce method using cold-mix asphalt mixtures and has a constant quality and has develop repair materials of pre-production asphalt-precast types. METHODS: The selection of the repair material was determined as the results obtained through physical properties of materials and the field applicability. In case of repair materials, values obtained through Marshall stability test & the dynamic stability test & retained stability test as well as the site conditions was considered. In case of adhesive, test results were obtained through examination of the bond strength(tensile, shear) and the field applicability of the adhesive was examined through combined specimens to simulate field applications. RESULTS : According to the results of laboratory tests, in the case of repair materials, Marshall stability and dynamic stability, retained stability of cold-mix reaction type asphalt mixture is the highest. In the case of adhesive, two-component epoxy-urea has a very high bonding strength(tensile, shear) was most excellent. According to the results of field tests, when epoxy-urea was excellent workability. Also, the repair body through actual mock-up test did not occur large deformation and fracture after 12 months. CONCLUSIONS : A suitable repair material is cold-mix reaction type mixture of asphalt-precast, a suitable adhesive is a two-component epoxy-urea.

• 한국통신학회논문지
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• 제25권8B호
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• pp.1469-1476
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• 2000

증가형 MOS FET에서 강반저의 경우 드레인 전류는 모두 드리프트에 기인하여 흐르기 때문에 I-V모델링시 수직전계와 수평전계를 함께 고려하여야한다. 특히 게이트전압 인가시 발생되는 수직전계는 표면이동도에 영향을 크게 주고 이로 인해서 캐리어들의 정상적인 흐름이 저해되는데 본 논문에서 제안한 다중 box분할법에 의하여 반전층의 깊이를 구하여 이동도 모델에 영향을 크게 미치는 반전층 내에서의 수직전계를 수치해석하였다.

• 지구물리와물리탐사
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• 제5권3호
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• pp.199-205
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• 2002

전기비저항 탐사에서 측정되는 양은 두 전위전극 사이의 전위차이다. 이 전위차가 양일 경우에는 겉보기 비저항도 양의 값을 가지며, 음일 경우에는 겉보기 비저항도 음의 값을 나타낸다. 또한 측정되는 전위차의 부호는 전기장의 방향에 따라 좌우된다. 만약 측정방향과 전기장의 방향이 같다면, 전위차와 겉보기 비저항은 양의 값을 보이게 되며, 그 반대의 경우에는 음의 값을 나타낸다. 일반적으로 지표 전기비저항 탐사에는 측정방향과 1차 전기장의 방향이 같은 전극 배열을 사용하며, 이 방향의 1차 전기장은 2차 전기장에 비하여 항상 크다. 따라서 일반적인 전극배열을 사용하는 지표 전기비저항 탐사의 경우에는 지형이 평탄하고 잡음이 없다면 음의 겉보기 비저항은 나타나지 않는다. 그러나 시추공-시추공 전기비저항 탐사의 경우에는 1차 전기장의 방향과 측정방향이 일치하지 않으며, 경우에 따라서는 1차 전기장의 측정방향 성분이 2차 전기장의 측정방향 성분 보다 그 크기가 작을 수 있다. 이 경우 2차 전기장의 방향과 측정방향이 서로 반대일 경우에는 음의 겉보기 비저항이 나타날 수 있다. 따라서 음의 겉보기 비저항은 측정방향의 1차 전기장이 매우 작은 영역에서 발생할 가능성이 높다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1270-1273
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• 2004

The mechanism design is synthesis of suitable mechanism which can be output motions about input motions. That has generally two steps which are the type synthesis and the dimensional synthesis. And required mechanism analysis step for confirming middle or final result. The type synthesis is definition of mechanism type which required aim and the dimensional synthesis is calculation of dimension about defined type mechanism. The type synthesis of mechanism is included qualitative design field which isn't defined systematic design method. especially, the most difficult step for mechanism design automation. In this paper proposed the component modular design method which is figured mechanism types automate with component modules using component modular approach. And develop CAD(Computer Aided Program) program for application.