• 제어로봇시스템학회논문지
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• 제17권7호
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• pp.714-719
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• 2011

This paper proposes a scheme for distributed load balancing in mobile communication networks based on supervisory control framework. Using load information exchanged with neighboring cells, the "supervisors" that reside in the base stations distribute load among cells by controlling handover parameters in a distributed manner. The supervisors are designed so that the load difference among neighboring cells are kept under a pre-defined value. Results from systematic analysis and simulation indicate that our scheme effectively balances traffic load among cells and reduces call blocking rate of the overloaded cells.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.38-50
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• 2018

Spatio-temporal load forecasting (STLF) is a foundation for building the prediction-based power map, which could be a useful tool for the visualization and tendency assessment of urban energy application. Constructing one point-forecasting model for each electricity cell in the geographic space is possible; however, it is unadvisable and insufficient, considering the aggregation features of electricity cells and uncertainties in input variables. This paper presents a new STLF method, with a data-driven framework consisting of 3 subroutines: multi-level clustering of cells considering their aggregation features, load regression for each category of cells based on SLS-SVRNs (sparse least squares support vector regression networks), and interval forecasting of spatio-temporal load with sampled blind number. Take some area in Pudong, Shanghai as the region of study. Results of multi-level clustering show that electricity cells in the same category are clustered in geographic space to some extent, which reveals the spatial aggregation feature of cells. For cellular load regression, a comparison has been made with 3 other forecasting methods, indicating the higher accuracy of the proposed method in point-forecasting of spatio-temporal load. Furthermore, results of interval load forecasting demonstrate that the proposed prediction-interval construction method can effectively convey the uncertainties in input variables.

• Current Photovoltaic Research
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• 제4권2호
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• pp.48-53
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• 2016

We report the effect of physical load on the stability of organic solar cells under physical loads. The active layers in organic solar cells were fabricated with bulk heterojunction films (BHJ) films of poly (3-hexylthiophene) and phenyl-$C_{61}$-butyric methyl ester. The loading time was varied up to 60 s by keeping the physical load constant. Results showed that the open circuit voltage was not influenced by the physical load but other solar cell parameters were sensitive to the loading time. The fill factor was very slightly increased at 15 s, while short circuit current density was well kept for 30 s. The power conversion efficiency was reasonably maintained for 45 s but became significantly decreased by the continuous loading for 60 s.

• 한국통신학회논문지
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• 제39A권5호
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• pp.280-292
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• 2014

기존의 매크로 셀룰러 망 환경은 공간 재사용의 한계로 인해 최근 급증하는 데이터 트래픽을 제대로 지원할 수 없게 되었다. 이 문제를 극복하기 위해 매크로 셀룰러 망위에 스몰 셀이 설치되어 적극적인 공간 재사용이 가능한 이종 셀룰러 망이 등장하게 되었다. 하지만, 매크로 셀과 스몰 셀 사이의 전송전력 차이로 인해 매크로 셀에 집중된 부하를 스몰 셀로 충분히 분산 시킬 수 없었다. 따라서, 프레임의 일정구간에서 매크로 셀의 전송전력을 차단하는 almost blank subframe (ABS) 와 스몰 셀 커버리지를 확장하여 사용자 부하를 스몰 셀로 강제 분산시키는 cell range expansion을 결합한 enhanced inter-cell interference coordination (eICIC) 기법이 제안되었다. 그러나, 이러한 eICIC 기법만으로는 효과적인 부하 분산을 달성하기 어렵다. 본 논문에서는 eICIC 기법이 적용된 이종 셀룰러 망 환경에서 비례공정을 향상시키는 부하 분산 기법을 제안한다. 구체적으로 제안된 기법은 탐욕 알고리즘 기반의 사용자의 소속 기지국 전환과 ABS 구간비율 갱신을 재귀적으로 결합하여 부하 분산을 실행한다.

• 한국생산제조학회지
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• 제19권6호
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• pp.724-730
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• 2010

A load cell is a converter that generates voltage signals when a certain force is effected in a given direction. An essential measurement device for electronic scales that indicate weight by numbers. These load cells are being applied in various areas such as daily life, distribution, laboratory and industrial. Recently the study to manufacture load cells in a more simple method while increasing performance is being persisted. In this study based on the comparison of load cells manufactured through single surface processing using strain gauges. Those manufactured through dual surface processing using strain gauges. Ultimately persist a more simple method of load cell manufacturing while increasing its performance. The elements that were compared were linearity, hysteresis, creep and eccentricity which are short tenn performance factors. The conclusion was that single surface processing showed almost identical data as that of dual surface processing, and the load cell error rate(0.005%) also excess regulation. The manufacturing time was shortened while mass-production was possible. Which indicates a development in the weighing industry.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2001년도 추계학술대회 학술발표 논문집
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• pp.78-82
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• 2001

Electronic Weighting Machine is used an electronic scale which has many trouble because of broken load cells. In this paper, we propose an intelligent Diagnosis System will for an electronic weighting machine using fuzzy logic. It's purpose be detect of the load cell's trouble. The electronic circuit of system, which call 'junction box', will be connected resistances in a series at circuit of Wheatstone Bridge for monitoring the condition of load cells.

• 한국정밀공학회지
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• 제7권2호
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• pp.58-64
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• 1990

As the miniature load cells have small inner space and sensing elements of which are thin and very sensitive to manufacturing conditions, it is very difficult to predict the rated outputs and control them by using the compensation resistor. The very useful equation has been derived for calculation of theoretical rated outputs for diaphragm type miniature load cells when commercial diaphragm strain gages are used. Four diaphragm type miniature load cells of which capacities are from 300 N to 1, 000 N and outer diameters are 20 mm and 26.5 mm are manufactured. The differences between calculating results and actural ones are less than 5%. According to numerical analysis the decrease of rated outputs caused to main error is examined in existence of loading button.

• 산업기술연구
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• 제12권
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• pp.25-36
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• 1992

In this paper, we simulate and calculate the stress and output voltage of the beam structure load cells by using FEM as varing physical structure parameters and loading positions. It is proved that stress enhance as the increase of the notch pitch and radius of the load cell, but decrease as the increase of the notch thickness and beam width. The results are good matched for basic formulas of the single fixed beam, and are verified our simulation is correct. Also, it is found that the stress characteristics of the load cell is varied according to loading positions with structure parameters, and caculated output voltage of the load cell approximate to those of the real manufactured ones. As a result, this study will offer efficient design and analysis technique for making special and variety capacity of load cells.

• 한국통신학회논문지
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• 제40권11호
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• pp.2230-2237
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• 2015

본 논문에서는 자연계에 존재하는 동기화 현상에 착안하여 무선 네트워크를 위한 자율적 부하균형 기법을 제안한다. 이를 위해 본 논문에서는 무선 접속 서비스를 제공하는 셀 사이의 부하균형 문제를 자연계 동기화 현상을 이용하여 모델링 한 후 각 셀들이 이웃 셀과의 부하 차이에 따라 자율적으로 부하를 분배하기 위한 알고리즘을 설계한다. 모의실험을 통해 제안 기법을 이용하여 각 셀들이 자신의 지역적 정보만을 이용하여 자율적으로 부하 분배 여부를 결정하더라도 셀 간 부하균형을 이룰 수 있다는 것을 검증하였다.

• 태양에너지
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• 제18권4호
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• pp.23-32
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• 1998

Fuel cells supply electric power and heat at work, and their exhaust gas is comparatively clear. So they are in the limelight as one of the co-generation systems which behave friendly with the environment. Fuel cells discharge both steam and hot water. Accordingly, if we combine absorption heat pump driven by waste heat with fuel cells, we can construct an advanced energy conserving system. The purpose of this study is the objective for evaluating the possibilities of effectively utilizing waste heat of fuel cells as a heat source for the single and double effect absorption systems. Simulation studies on single and double effect absorption have been performed for water/lithium-bromide pair. The effectiveness of introducing a waste heat source of fuel cells is demonstrated. The result of this study showed that total efficiency was about 85% at rated operation and about 75% at 75% load operation. Absorption cycle moved to more strong concentration when fuel cell operated at 75% load.