• 한국정보통신학회논문지
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• 제26권3호
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• pp.469-478
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• 2022

본 논문은 산업용 생산 장비의 부하 전력을 모니터링하기 위한 스마트 디바이스와 애플리케이션을 개발하고 성능을 평가한 결과를 담고 있다. 스마트 디바이스는 산업용 생산 장비의 부하 전력 및 동작 환경 데이터를 수집해 이를 서버로 전송하는 기능을 가진 스마트 전력 디바이스와 이의 경량화 버전에 해당하는 에너지 미터링 디바이스로 구분해 하드웨어와 더불어 펌웨어를 개발하였다. 이들 디바이스에서 수집한 부하 전력 데이터는 AWS(Amazon Web Services) 서버내 MariaDB에 저장될 수 있도록 하였으며, RESTFul API를 이용해 웹사이트 및 모바일 애플리케이션 상에서 그래프 형태로 부하 전력을 모니터링할 수 있도록 구현하였다. 개발 시스템의 성능을 평가하기 위해 MariaDB에서 웹사이트 및 모바일 애플리케이션까지의 응답 시간을 측정하였으며, 4G(LTE) 네트워크 환경에서는 0.0256~0.0545초, 3G 네트워크 환경에서는 0.6126~1.2978초로 만족스러운 결과를 보여줌을 알 수 있었다.

• 전기학회논문지
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• 제65권9호
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• pp.1626-1631
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• 2016

Generally, the low-voltage customer has been used with a linear load and nonlinear load in the 3-phase 4-wire distribution system. Linear load has usually configured the resistance and inductance, current phase is slower than the voltage phase, so power factor is low. It is required for the power factor correction device prior to the phase of the current than the voltage. The capacitor is connected in parallel to the load in order to ensure a low power factor. Power converter such as an inverter is a typical non-linear load. Non-linear load generates harmonic currents in the energy conversion process. Many electrical equipment may be adversely affected by the harmonic current. There, passive or active filter have been used to reduce these harmonics current. Passive filter consisting of inductor and capacitor generates a reactive power. According to the combination of filter inductor and capacitor, reactive power can be adjusted. In this paper, we analyzed how the combination of inductor and capacitor affects the overall power factor by simulation and measurement.

• 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.

• Structural Engineering and Mechanics
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• 제60권6호
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• pp.939-952
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• 2016

A compression to tensile load transforming (CTT) device was developed to determine indirect tensile strength of concrete material. Before CTT test, Particle flow code was used for the determination of the standard dimension of physical samples. Four numerical models with different dimensions were made and were subjected to tensile loading. The geometry of the model with ideal failure pattern was selected for physical sample preparation. A concrete slab with dimensions of $15{\times}19{\times}6cm$ and a hole at its center was prepared and subjected to tensile loading using this special loading device. The ratio of hole diameter to sample width was 0.5. The samples were made from a mixture of water, fine sand and cement with a ratio of 1-0.5-1, respectively. A 30-ton hydraulic jack with a load cell applied compressive loading to CTT with the compressive pressure rate of 0.02 MPa per second. The compressive loading was converted to tensile stress on the sample because of the overall test design. A numerical modeling was also done to analyze the effect of the hole diameter on stress concentrations of the hole side along its horizontal axis to provide a suitable criterion for determining the real tensile strength of concrete. Concurrent with indirect tensile test, the Brazilian test was performed to compare the results from two methods and also to perform numerical calibration. The numerical modeling shows that the models have tensile failure in the sides of the hole along the horizontal axis before any failure under shear loading. Also the stress concentration at the edge of the hole was 1.4 times more than the applied stress registered by the machine. Experimental Results showed that, the indirect tensile strength was clearly lower than the Brazilian test strength.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.387-388
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• 2002

A Brake device for the high-speed impacting object is designed using an axial crushing of thin-walled metal cylinder, Thickness of the cylinder is increased smoothly from the impacting end to the fixed end, resulting in the truncated cone shape. Truncated cone shape ensures that plastic hinges are formed sequentially from impacting end. This increases the reliability of brake device working. Computational and real experiments were performed to verify the effects of conical angle. Results indicate that undesirable sudden rise of crushing load can be prevented by applying appropriate conical angle.

• 설비공학논문집
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• 제18권9호
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• pp.707-713
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• 2006

To improve heating performance of the heat pump in winter season, refrigerant heating device was applied to conventional heat pump. The refrigerant heating device operates at the heating capacity does not enough to the heating load requirement of the conditioning space. When the discharge air temperature of the indoor heat exchanger goes down to below $40^{\circ}C$ which is criterion for comfort of the occupants in the conditioning space, the system also starts. The refrigerant heating system has new concept of auxiliary heating device for heat pump in winter. In this study, the system performance was analyzed through experiments and parametric study was conducted to improve the COP and control strategies.

• 조명전기설비학회논문지
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• 제28권9호
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• pp.83-88
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• 2014

When DG interconnection into network is examined, details of the review are overvoltage, protective device malfunction, etc. In the case of protective device malfunction, replacing protective device into bi-directional protective device and installation NGR are the solution. Overvoltage at interconnection point occurs because the load is relatively less than DG output. When overvoltage at interconnection point occurs, DG interconnection is not permitted because this overvoltage affect other customers. Interconnection by installation new distribution line is one solution but it costs much money. Without installation new investment, change of NOP(Normal Open Point) position is a possible solution about DG interconnection into network.

• Current Photovoltaic Research
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• 제4권4호
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• pp.131-139
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• 2016

This paper shows the series power device in the massive roof-top PVs and domestic loads. D-UPFC as the series power device controls the distribution voltage during voltage rise (or fall) condition. D-UPFC consists of the bi-directional ac-ac converter and the transformer. In order to verify the D-UPFC voltage control, the distribution model is used in the case study. D-UPFC enables the voltage control in the distribution voltage range. Dynamic voltage control from voltage rise and voltage fall conditions is performed. Scaled-down experimental test of the D-UPFC is verified the voltage control and it is well performed without high voltage spikes in the inductive load.

• 한국생산제조학회지
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• 제22권3_1spc호
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• pp.531-536
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• 2013

An automatic wax-ring manufacturing system for silk coating was developed, which consisted of a container, pallet with a cooling part, injection port, and removing device. The removing device is a system to load, lift, and cut the wax-ring, which is widelyused for various silk-coating industrial purposes. A novel removing device equipped with a water cooling circulation system is proposed in this paper. It has the benefit of easy control, as well as the convenience of loading and unloading without the use of other equipment. Three-dimensional modeling techniques were adopted to develop integrated functions for the automatic wax-ring manufacturing system, which made it possible to confirm the smooth integration/interface of each part and the system's interrelations with other manufacturing systems.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.143-151
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• 2001

In the recent day, fatigue life prediction techniques play a major role in the design of components in the ground vehicle industry. Full scale durability testing in the laboratory is an essential of any fatigue life evaluation of components or structure of the automotive vehicle. Component testing is particularly important in todey's highly competitive industries where the design to reduce weight and production costs must be balanced with the necessity to avoid expensive service failure. Generally, Multi-axis durability testing device is used to carry out the fatigue test. In this paper, The operation software for simultaneously driving Multi-axis vibration testing device is developed and the input and output data are displayed in windows of PC controller with real time. Moteover the characteristics of the displacement and the load of Multi-axis actuators are calibrated separately.