• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1060-1067
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• 2004

In a CDMA system, the rapacity is variable and mainly depends on multiple access interference. The multiple access interference has a deep relationship with transmitted or received power. The capacity of CDMA2000 1x system is considered to be limited by the forward link capacity. In this paper, we show that the transmitted power can represent the total cell load and we propose a load control scheme for CDMA2000 1x system. CDMA2000 1x system has fast power control scheme and we can measure forward link cell load by using total transmitted power. In the proposed algorithm, by monitoring the total transmit power, we can simply adjust data rate to channel conditions and efficiently use radio resources. The proposed algorithm is practical algorithm to implement in the power controlled CDMA systems and enhances the system throughput and quality of service(QoS)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.11
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• pp.737-742
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• 2015

This paper is designed to find out where power reaches the highest point as the load of solar cells varies. In addition, the current and power were measured when irradiation changes, and the correlation between current and power was investigated. On top of that, experiments were conducted with the light volume kept constant and with the incoming light angle changing in order to figure out the incoming light angle that produces the most power and to conduct analyses. It was ascertained that if the load increases, the current decreases and the voltage increases. Since the power of 0.9828[W] was the highest when measurements were done, it can be said that when a load of 30[%] is applied to the solar cells, they are the most efficient.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1540-1546
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• 2000

Recently, force measurement systems are commonly used in many industrial fields and the precision of the measurement system is getting more important as the industry needs more precise tools and in struments to make high quality products. However, a high precision force measurement system is hard to make unless we know precisely the causes, quality and quantity of measurement errors in advance. In this work, many possible mechanical causes of measurement errors are reviewed including ratio of length to diameter of sensing part, radius of contact area, radius of bearing part, ratio of material properties and change of boundary conditions. Also, the measurement errors are analyzed by nonlinear finite element method and the nonlinear behavior of the errors are investigated. The results can be used to design force measurement systems and expected to be very useful especially for compact type load cells.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.44-49
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• 2011

The crawler crane, which consists of a lattice boom, a driving system, and movable vehicle, is widely used in a construction site. It needs to be installed an overload limiter to prevent the overturning accident and the fracture of structure. This research is undertaken to provide the relation formula for designing the overload limiter as follows: First the relation formulas between the wire-rope tension and the hoisting load or the overturning ratio according to the luffing angle and length of a lattice boom are established. Secondly the derived formulas are corrected by using the compensated angle considering the deflection of boom through the finite element analysis. The stiffness analysis is carried out for 30-kinds of models as a combination of 6-kinds of luffing angle and 5-kinds of length of boom. Finally the shape design of a stick type load cell, which is the device to measure the wire-rope tension, is performed. 5-kinds of notch radius and 5-kinds of center hole radius are adopted as the design parameter for the strength analysis of the load cell.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.577-584
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• 2007

Uroflowmetry is non-invasive and easily performed to diagnose benign prostatic hypertrophy(BPH) frequent in aged men. Weight change during urination is usually measured to estimate the urinary flow rate by a load cell, but sensitive to any impacts against the bottom of the container, leading to unnecessary noise generation. Moreover, load cells are relatively expensive raising the production cost. The present study proposed a new technique, measuring hydraulic pressure on the bottom of the urine container to evaluate the urinary volume. Low cost pressure transducer enabled almost perfectly linear relationship between the urine volume and the hydraulic pressure. During both the simulated and human urination experiments, variance of the pressure signal was more than 50% smaller than the weight signal acquired by a load cell, which demonstrated that the impact noise was decreased to a great degree by pressure compared to weight measurement.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.89-98
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• 2005

Preliminary pile load tests for the design of large diameter drilled shaft were performed on two of reduced scale(D=1370mm) test piles. The maximum loads of 2350 tonf in each direction were applied using bi-directional hydraulic jacks(Osterberg Cell) at toe. Neither of the test piles yielded in terms of skin friction and end bearing. Comparisons of the test results with several methods that estimate pile capacity show that the method of Horvath and Kenney(1979) for skin friction and Zhang and Einstein(1998) for end bearing were most appropriate for the site. The test results were directly applied to pile design in case RQD of skin and toe was larger than that of the test pile. It is desirable, therefore, to consider not only unconfined compression strength but also rock mass properties(i.e. TCR, RQD) for skin friction and end bearing evaluation in the future.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.323-330
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• 2012

The use of lattice girder is increased rapidly as a substitute for H-steel ribs at the tunnel sites in Korea. Ground loads acting on the tunnel are supported by shotcrete and lattice girders. To assess the safety of the tunnel, it is essential to obtain field measurements for the lattice girders; however, lattice girder measurements have rarely been performed at tunnel sites, and the method of measurement is not well established. In the present study we suggest a load cell method for the instrumentation of tunnels with lattice girders. Actual measurements of ground loads acting on lattice girders are presented for a specific tunnel under construction.

• Journal of Sensor Science and Technology
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• v.16 no.3
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• pp.179-186
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• 2007

Uroflowmetry is non-invasive and easily performed to diagnose benign prostate hypertrophy (BPH) frequent in aged men. Weight change during urination is usually measured to estimate the urinary flow rate by a load cell, but sensitive to any impacts against the bottom of the container, leading to unnecessary noise generation. Moreover, load cells are relatively expensive raising the production cost. The present study proposed a new technique, measuring hydraulic pressure on the bottom of the urine container to evaluate the urinary flow rate. Low cost pressure transducer enabled almost perfectly linear relationship between the urine volume and the hydraulic pressure. During both the simulated and human urination experiment, variance of the pressure signal was more than 50 % smaller than the weight signal acquired by a load cell, which demonstrated that the impact noise was decreased to a great degree by pressure compared to weight measurement.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.591-604
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• 2008

In this study, two design examples of drilled shafts on soft ground in Ho-Chi-Minh City, Vietnam are introduced. One is for a 27-story apartment and the other is for a Arch bridge over Saigon river. Unlikely the normal cases in Korea, all of the bored pile foundations are supposed to be placed on soil layers. Therefore, skin friction between pile and ground is the most crucial design parameter. Three methods using SPT N value of sandy soil -Korean Road Bridge Code(1996), Reese and Wright (1977), and O'Neill and Reese (1988)- were adopted to obtain an ultimate axial bearing capacity. In order to verify the calculated bearing capacity, 3 sets of static load test and a Osterberg Cell test were performed at an apartment site and a bridge site respectively. LRFD (Load Resistance Factored Design) method was compared with ASD (Allowable Stress Design) method. On application of ASD method, safety factor for skin friction was adopted as 2 or 3 while safety factor for end bearing was 3. The design bearing capacities from ASD method matched well with those from LRFD method when safety factor for skin friction was adopted as 2.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.608-619
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• 2018

As distributed generation (DG) is connected to grid, there is new node-type occurring in distribution network. An efficient algorithm is proposed in this paper to calculate power flow for weakly meshed distribution network with DGs in different load models. The algorithm respectively establishes mathematical models focusing on the wind power, photovoltaic cell, fuel cell, and gas turbine, wherein the different DGs are respectively equivalent to PQ, PI, PQ (V) and PV node-type. When dealing with PV node, the algorithm adopts reactive power compensation device to correct power, and the reactive power allocation principle is proposed to determine reactive power initial value to improve convergence of the algorithm. In addition, when dealing with the weakly meshed network, the proposed algorithm, which builds path matrix based on loop-analysis and establishes incident matrix of node voltage and injection current, possesses good convergence and strong ability to process the loops. The simulation results in IEEE33 and PG&G69 node distribution networks show that with increase of the number of loops, the algorithm's iteration times will decrease, and its convergence performance is stronger. Clearly, it can be effectively used to solve the problem of power flow calculation for weakly meshed distribution network containing different DGs.