• Journal of Magnetics
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• 제20권4호
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• pp.421-426
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• 2015

This paper presents a practical method for estimation of average temperature in the permanent magnet (PM) of electric machine by using finite element analysis (FEA) and dynamo load experiment. First of all, the temperature effect of PM to the torque has been employed by FEA in order to evaluate the Temperature-Torque characteristic curve. The 1st order polynomial equation which is torque attenuation coefficient is derived by the FEA result of the Temperature-Torque curve. Next, torque saturation test with constant current condition is performed by dynamo load experiment. Then, the temperature trend can be estimated by adding the initial starting temperature using the torque attenuation coefficient and torque saturation curve. Lastly, estimated temperature is validated by infrared thermometer which measures temperature of PM surface. The comparison between the estimated result and experimental result gives a good agreement within a deviation of maximum $8^{\circ}C$.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.740-741
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• 2015

the downscaled air temperature data over study region for the projected 2001 - 2099 period were then ensemble averaged, and the ensemble averages of 6 realizations were compared against the corresponding historical downscaled data for the 1961 - 2000 period in order to assess the impact of climate change on air temperature over study region by graphical, spatial and statistical methods. In order to evaluate the seasonal trends under future climate change conditions, the simulated annual, annual DJF (December-January-February), and annual JJA (June-July-August) mean air temperature for 5 watersheds during historical and future periods were evaluated. From the results, it is clear that there is a rising trend in the projected air temperature and future air temperature would be warmer by about 3 degrees Celsius toward the end of 21^st century if the ensemble projections of air temperature become true. Spatial comparison of 30-year average annual mean air temperature between historical period (1970 - 1999) and ensemble average of 6-realization shows that air temperature is warmer toward end of 21^st century compared to historical period.

• Environmental Engineering Research
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• 제20권3호
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• pp.290-297
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• 2015

This paper presents the evaluation of the impact of climate change on water resources and yield capacity of Asa and Kampe reservoirs. Trend analysis of mean temperature, runoff, rainfall and evapotranspiration was carried out using Mann Kendall and Sen's slope, while runoff was modeled as a function of temperature, rainfall and evapotranspiration using Artificial Neural Networks (ANN). Rainfall and runoff exhibited positive trends at the two dam sites and their upstream while forecasted ten-year runoff displayed increasing positive trend which indicates high reservoir inflow. The reservoir yield capacity estimated with the ANN forecasted runoff was higher by about 38% and 17% compared to that obtained with historical runoff at Asa and Kampe respectively. This is an indication that there is tendency for water resources of the reservoir to increase and thus more water will be available for water supply and irrigation to ensure food security.

• 세라미스트
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• 제22권3호
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• pp.256-268
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• 2019

Ceramic nano pigments have attracted much interest owing to recent demand for nontoxic, heavy metal-free pigments. In general, ceramic pigments must possess thermal stability at high temperature, however nanosized powder easily undergoes aggregation at high temperature, and its color turns. serveral groups have focused on to minimize agglomeration and oxidation, a core-shell structure with a silica coating is suggested. In this review, we introduce the reported the trend of nano-ceramic powders and we summarized method improve color and physical properties throuth morphology control and ceramic coating technology.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2004년도 전지기술심포지움
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• pp.75-108
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• 2004

The market, development and trend of Lithium ion Batteries in China are introduce briefly. Early, Chinese manufactories were busy to expand and many new battery factories have been built up. Now, the relatively large companies pay more attentions on comprehensive quality improvement, therefore the production processing and facilities have been also modified in some extent. The recent technology progresses focus on High capacity (energy density), High rate, High average voltage, High safety, High temperature properties, Long cycle life, Low temperature properties, Low self discharge, Low cost, Super-large, Super-small, Super-thin, Consistency, Customization, and Environment friendly processing, simply $H_5L_4S_3C_2E_1$. Lithium ion polymer batteries which all batteries packaged with soft lamination film are named as in China have a quick growth and emphasized here because of their advantages ins $H_5L_4S_3C_2E_1$ for which it is quite difficult to be realized at the same time. Some of research works such as listed above are introduced. The other contends related to application trend of Lithium ion batteries and projects carrying out are also included.

• 한국주조공학회지
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• 제29권6호
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• pp.257-264
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• 2009

The effects of silicon and molybdenum on the temperature-dependent properties of high silicon and high molybdenum ductile cast iron were investigated. Microstructure was composed of ferrite, cell boundary complex carbide, carbide precipitated in the grain and graphite. The number and size of carbide decreased with the increase of silicon content and increased with the increase of molybdenum content, however, the size of cell boundary carbide increased above 0.81wt%Mo. The room temperature tensile strength increased with the increase of silicon and molybdenum contents. That did not increase with the latter with more than 0.8wt%. Meanwhile the high temperature tensile strength showed the similar trend to that of room temperature one, that of the specimen with 0.55wt%Mo was the highest. The $A_1$ transformation temperature increased with the silicon and molybdenum contents, and showed similar tendency with the variation of strength. It was discussed due to the solubility limit of Molybdenum in ferrite, of which value was assumed to be in the vicinity of 0.81wt%Mo. The weight after oxidation at 1,173K showed the result caused by the difference in solubility of molybdenum in the matrix. That and the thickness change after oxidation did not show any consistent trend with the silicon and molybdenum contents.

• Journal of the Korean Data and Information Science Society
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• 제20권5호
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• pp.765-777
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• 2009

본 연구에서는 대기오염물질 중에서 주목을 받고 있는 분진 직경이 10마이크로미터 (micrometer) 이내의 것을 대상으로 실제로 증가하는지 감소하는지를 알아보기 위하여 교락 요인을 제외한 분진을 대상으로의 순수한 장기 추세를 연구하였다. 자료는 1996년에서 2000년까지 서울시의 기상 변수들 (최대기온, 평균습도, 최대풍속, 일사량)과 27지점에서 얻은 분진 직경이 10마이크로미터 이내의 것을 이용한다. 이 자료를 이용하여 분진과 비선형 관계를 보이는 기상 변수들의 회귀 스플라인을 이용하여 계절성을 통제한 일반화 부가모형을 세웠다. 그 결과 증가가 아닌 감소하는 순수 장기 추세를 얻을 수 있었다.

• 한국추진공학회지
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• 제12권6호
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• pp.1-6
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• 2008

본 연구에서는 계측 데이터의 성능 추이를 분석하여 가스터빈 엔진의 결함 여부를 탐지하기 위한 퍼지 경향감시 방법을 제안하였다. 제안된 경향감시 방법은 연료유량, 배기가스 온도, 로터회전수, 진동수와 같은 중요 엔진 파라미터를 모니터링 하여 시간에 따른 변화를 분석하여 엔진 상태를 진단하는 것이다. 이를 위해 먼저 선형회귀분석을 통해 엔진 상태 변화를 수식화하고 퍼지 로직을 통해 진단 결과를 분석하여 예측되는 손상 원인을 제시한다.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.455-465
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• 2021

The Molten Salt Reactor (MSR), one of the six advanced reactor types of the 4th generation nuclear energy systems, has many impressive features including economic advantages, inherent safety and nuclear non-proliferation. This paper introduces a system analysis code named TREND, which is developed and used for the steady and transient simulation of MSRs. The TREND code calculates the distributions of pressure, velocity and temperature of single-phase flows by solving the conservation equations of mass, momentum and energy, along with a fluid state equation. Heat structures coupled with the fluid dynamics model is sufficient to meet the demands of modeling MSR system-level thermal-hydraulics. The core power is based on the point reactor neutron kinetics model calculated by the typical Runge-Kutta method. An incremental PID controller is inserted to adjust the operation behaviors. The verification and validation of the TREND code have been carried out in two aspects: detailed code-to-code comparison with established thermal-hydraulic system codes such as RELAP5, and validation with the experimental data from MSRE and the CIET facility (the University of California, Berkeley's Compact Integral Effects Test facility).The results indicate that TREND can be used in analyzing the transient behaviors of MSRs and will be improved by validating with more experimental results with the support of SINAP.

• Tribology and Lubricants
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• 제12권3호
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• pp.33-38
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• 1996

High temperature wear behaviors of plasma-sprayed ZrO$_{2}$-$Y_{2}O_{3}$ composite coatings were investigated for high temperature wear resistance applications. The composite powders containing 20, 50, 80 vol% of alumina for plasma spray were made by spray drying method. Wear tests with composite coated specimens were performed at temperature ranges from room temperature to 800$^{\circ}$C. Wear tests were also carried out with heat treated specimens at room temperature. The microstructural change of coatings and the worn surface were examined by SEM and XRD. Sharp increase of wear loss at high temperature wear test was observed in specimens containing 50 and 80 vol% alumina. Similar trend was observed in the heat treated coatings. The measured residual stress was increased with increased alumina contents and heat treating temperatures. Residual stress induced during heat treatment appeared to be responsible to the observed harmful effect of alumina additions on the high temperature wear.