• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.822-824
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• 2000

To apply HTS to AC devices, it is necessary that study theoretically and experimentally to analyze the AC losses. It should be investigated the theoretical mechanisms precede the actual experiments. Because the AC losses cause some complicated troubles in AC machines, we can design the machines properly. In this study, firstly we analyze the basic cause of AC losses by investigating the several loss factors, secondly measure the AC losses of HTS by using Magnetization. Technique and this results show that AC losses of HTS is tenuous than those of general materials used in power system. Consequently we can compare the actual results with the theoretical results. And we find that AC losses of HTS are related to the amplitude of external magnetic field and the frequency. Through this study, we find that it is possible to apply the results by Magnetization. Technique to the AC power system, to the design of AC machine, to design of HTS proper to the foretold AC losses.

• 한국축산식품학회지
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• 제41권1호
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• pp.16-33
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• 2021

To stop hunger, reducing food losses is a potential movement towards saving food. A large portion of these losses could be avoided and reduced through the improved food chain in many countries. Raising awareness on how and where food losses occur will help recovering foods such as meat by identifying solutions and convincing people to implement those solutions. This, in turn, will lead to private and public efforts to recover meat that might be otherwise wasted. After highlighting the importance of food saving benefits and relevant statistics, this paper explains the possible ways to reduce meat loss and waste in abattoirs and presents a framework for prevention according to the estimates of meat losses in Iran meat supply. The current article answers the questions of where do we have the meat loss in Iran and what approaches are most successful in reducing losses in the meat industry. The national average loss and waste in meat production are about 300,000 metric tonnes (about 15%). Many segments and players are involved with this huge amount of losses in the meat value chain, a large portion of these losses could be avoided and reduced by about 25% through using by-products with the mechanization of design and manufacturing. The production amount of mechanically deboned meat (MDM) is 105,091,000 kg, concluding the major waste (88.33%) of total poultry losses. Ensuring appropriate actions by exploiting the full potential of engaged Iranian associations and institutes is considered to reduce the losses.

• 설비공학논문집
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• 제9권2호
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• pp.229-238
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• 1997

A third-order simulation model of VM heat pumps has been developed. This model allows consideration of the major losses such as heat conduction losses through regenerators and displacers, pumping losses and wall-to-gas heat transfer losses in working volumes, in addition to the heat exchanger and regenerator losses. The working volume was divided into 12 control volumes and conservation equations of mass and energy were applied to each control volume. Pressure drop was considered in regenerators only. Thermodynamic behavior of working fluid in a VM heat pump was investigated and effects of major losses on the performance of a VM heat pump were shown.

• 조명전기설비학회논문지
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• 제29권1호
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• pp.80-85
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• 2015

In the issues of interleaved topology which have been in limelight as high power converter, various soft-switching methods are studied to reduce switching losses in high power application. The interleaved ZCT converter has an additional filter inductor to reduce losses of diodes during reverse recovery process. However, additional current conduction modes are occurred by the inductor, we need to analyze switching losses with inductor values on each mode. In this paper, current conduction modes and boundary conditions of interleaved ZCT converter are analyzed. In the conclusion, the minimum of switching losses in converter operation modes is analyzed by calculating switching losses.

• 전기학회논문지P
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• 제66권4호
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• pp.219-223
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• 2017

In this paper, we calculated the losses in the high voltage lines of power distribution system. The losses caused by high voltage lines are calculated using maximum current, resistance, loss factor, and dispersion loss factor. The accurate extraction of these factors are very important to calculate the losses exactly. Thus, the maximum loads are subdivided to regions and calculated monthly for more accurate maximum current calculation. Also, the composite resistance is calculated according to the ratio of the used wire types. In order to calculate the loss factor, the load factors according to the characteristics of each region were calculated. Finally, the losses of the distribution system is calculated by adding the losses by the transformers and the low voltage lines.

• 노동경제논집
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• 제33권1호
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• pp.53-84
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• 2010

이 논문은 한국노동패널 조사 자료를 이용하여 실직자들이 겪는 임금 손실의 정도를 실직 발생 직후에서 부터 4년 후까지 분석하였다. 종전에 국내에서 이루어진 연구들에서는 주로 실직 직후에 발생하는 손실에 초점이 맞춰졌는데, 실직으로 인한 손실이 지속될 경우 이는 손실을 과소 추정하는 것이 된다. 논문의 분석 결과에 의하면 실직 발생 4년 후에도 실직으로 인한 임금 손실이 유의미하게 지속되는 것으로 나타났으며, 이는 실직으로 인해 발생하는 일자리 경험의 손실과 반복 실직의 발생에 크게 영향 받은 결과인 것으로 나타났다.

• Journal of Power Electronics
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• 제18권5호
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• pp.1325-1335
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• 2018

This paper presents a discontinuous pulse width modulation (DPWM) method to reduce switching losses in an indirect matrix converter (IMC) drive. The IMC has a number of power semiconductor switches. In other words, it consists of a rectifier stage and an inverter stage for AC/AC power conversion, which are composed of 12 and 6 switching devices, respectively. Therefore, the switching devices of the IMC suffer from high switching losses in the IMC drives. Various topologies to reduce switching losses have been studied by eliminating a number of switches from the rectifier stage. In this study, in contrast to prior research, a DPWM method is presented to reduce the switching losses of the inverter stage. The effectiveness of the proposed method to reduce switching losses in IMC drives is verified by simulations and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 추계학술대회 논문집
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• pp.33-34
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• 2014

In this paper, the inverter switch losses of BLDC motor for three types of PWM method and power devices was analyzed. When BLDC motor is driven at low currents, inverter switch losses for MOSFET is low because MOSFET operates like resistance. But, inverter switch losses for IGBT is higher than MOSFET due to its large turn-off losses. For low power inverter with MOSFET, the power losses of unified PWM is lower than that of unipolar and bipolar PWM.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.54-57
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• 1999

AC losses per cycle properties at 77K have been investigated on the Ag sheathed Bi2223 wire through two kinds of measuring methods(transport method and magnetic method). In case of transport method, the absolute value of losses agree with the results of Norris theory(strip and ellipse). In case of 19-filamentary tape, AC transport losses almost agree with those of magnetic method. In case of 1-filamentary tape, However, AC losses of magnetic method is smaller than AC transport losses

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.721-722
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• 2008

This paper deals with comparison and analysis for rotor losses of permanent magnet synchronous generator using phase current harmonic analysis according to dc and ac load. On the basis of analytical field analysis, the rotor losses are analysed. Particularly, rated speed and ac load and the rated speed and dc load conditions are considered. This paper compared rotor losses considered dc load with rotor losses considered ac load. Although our analytical modes is low speed, the rotor losses must be considered by results.