• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.2
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• pp.194-203
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• 1993

Quality Control programs for industrial hygiene laboratory have successfully been operated since the 1st round was initiated in April 1992. Three rounds have been completed. Overall analytical performance of participants was improved through a subsquent round. The first round had a large variation among analytical results of all participants, 26.34%~504.22% of coefficient of variation. But the variation of analytical performance in the 2nd and 3rd rounds decreased to 40.42%~52.55% and 10.74%~20.98%, respectively. The difference of analytical performance among participants was decreased by operation of subsquent round. By distribution of Running Performance Index (RPI), over 50% of participants belongs to Category 3 in the first round. The average percentage of participants assigned to Category 3 in the 2nd and 3rd round was decreased to 37.2%. A definite analytical performance improvement of participants seems to be obtained. "A" and "B" group have more participants assigned to Category 3 than those of "C" group through the distribution of RPI by group divided to similar participant. By the distribution of RPI all participants, the percent of participant being over 200 RPI in the 1st round was 43%~52%, but decreased to 9%~29% and 9%~27%, in the 2nd and 3rd round, respectively. These results mentioned above indicate that the analytical performance of all participants have been improved by subsquent Quality Control Program although newcomers joined and a few participants droped out. But, there are some participants with poor analytical performance. Industrial Health Research Institute (IHRI) will offer service such as education, communication and visitation to them, and improve quality of their analytical performance in the future.

• Journal of Power Electronics
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• v.16 no.1
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• pp.374-387
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• 2016

This paper derives an improved analytical model to estimate switching loss and analyze the effects of parasitic elements on the switching performance of SiC MOSFETs. The proposed analytical model considers the parasitic inductances, the nonlinearity of the junction capacitances and the nonlinearity of the trans-conductance. The turn-on process and the turn-off process are illustrated in detail, and equivalent circuits are derived and solved for each switching transition. The proposed analytical model is more accurate and matches better with experimental results than other analytical models. Note that switching losses calculated based on experiments are imprecise, because the energy of the junction capacitances is not properly disposed. Finally, the proposed analytical model is utilized to account for the effects of parasitic elements on the switching performance of a SiC MOSFET, and the circuit design rules for high frequency circuits are given.

• Journal of the Korean Society of Safety
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• v.28 no.2
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• pp.55-59
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• 2013

The analytical model was constituted to evaluate the flexural strength of UHPFRC(ultra high performance fiber reinforced concrete) member. The analytical approach was attemped to study the effect of the joint and the result compared with the experimental study to verify the analytical model. The calculated value tends to underestimate about 23%~25% in comparison with the experimental result of the jointed test member because the bond stress between precast UHPFRC and cast-in-place UHPFRC surface is not considered in the analytical model. But in the case of the continuous test member, the analytical model provides reasonable results for the flexural strength of UHPFRC member.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.3
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• pp.539-546
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• 1997

In this paper, we proposed a new mehtod to analyze the performance degradation by timing jitters in the APD (avalanche photodiode) receivers of intensity modulation/direct detection digital optical communication systems where raised cosine pulse-shaping filters are used to reduce the effect of noise while minimizing intersymbol interferences. The proposed analytical method is an extension of an analytical method we have already developed for pin diode receivers, and incorporates the effects of APD's multiplication factor and resulting shot noise. Using the proposed analytical method, we derive an approximated power penalty due to timing jitters based on an assumption of Gaussian distribution for timing jitters, and compare with that of the conventional analytical method. The results obtained from the proposed analytical method show that conventional analytical methods underestimate the influence of timing jitters on the reciver performance. The results also show that APD's multiplication factor which optimizes receiver sensitivity is smaller than that obtained by the conventional analytical method.

• Journal of Magnetics
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• v.19 no.1
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• pp.84-89
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• 2014

This paper presents an analytical prediction and experimental verification of the electromagnetic performance of a parallel magnetized surface-mounted permanent magnet (SPM) motor having a fractional number of slots per pole combination. On the basis of a two-dimensional (2-D) polar coordinate system and a magnetic vector potential, analytical solutions for flux density produced by the permanent magnets (PMs) and stator windings are derived. Then, analytical solutions for back-electromotive force (emf) and electromagnetic torque are derived from these field solutions. The analytical results are thoroughly validated with 2-D nonlinear finite element (FE) analysis results. Finally, the experimental back-emf and electromagnetic torque measurements are presented to test the validity of the analysis.

• Computers and Concrete
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• v.23 no.6
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• pp.459-470
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• 2019

Apart from strength properties, durability, toughness and workability are also important criteria in defining the performance of a concrete structure. Hence "High Performance Concrete (HPC)" is introduced. It is different from high strength concrete and can have various applications. In this paper, the properties (Mechanical and Durability) of High Performance Concrete blended with bagasse ash at 5%, 10%, 15% and 20% are studied. However, it is difficult to analyze the performance based on different properties obtained from different experiments. Hence it is necessary to combine all the criteria/properties into a single value to obtain a result by a technique called Analytical Hierarchy Process (AHP).It is an effective tool for dealing with complex decision making, and may aid the decision maker to set priorities and make the best decision. In addition, the AHP incorporates a useful technique for checking the consistency of the decision maker?s evaluations, thus reducing the bias in the decision making process.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.19-26
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• 1999

This paper describes an analytical study on nonlinear hysteretic behavior of hybrid steel beam with reinforced concrete ends. Two types of analytical model, Polygonal Model[PM] and Hybrid Model[HM], were used to represent the nonlinear hysteretic behavior PM used three parameters, HM used an additional parameter to consider the initial stiffness reduction. The parameters calibrated comparing the hysteretic performance obtained from experiments. The purpose of this study is to develop an analytical model which can take into account the initial stiffness reduction of the hybrid members and to represent exactly the hysteretic performance for the hybrid structures with RC and steel. The analytical study showed PM tends to overestimate initial stiffness and strength. However, HM which is capable to consider the initial stiffness reduction gave good prediction on initial stiffness, post-yielding performance, strength, pinching response and so on.

• Computers and Concrete
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• v.15 no.4
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• pp.563-588
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• 2015

Piers are the most vulnerable part of a bridge structure during an earthquake event. During Kobe earthquake in 1995, several bridge piers of the Hanshin Expressway collapsed for more than 600m of the bridge length. In this paper, the most important results of an experimental and analytical investigation of ten reinforced concrete bridge piers specimens with the same cross section subjected to constant axial (or variable) load and reversed (or one direction) cycling loading are presented. The objective was to investigate the main parameters influencing the seismic performance of reinforced concrete bridge piers. It was found that loading history and axial load intensity had a great influence on the performance of piers, especially concerning strength and stiffness degradation as well as the energy dissipation. Controlling these parameters is one of the keys for an ideal seismic performance for a given structure during an eventual seismic event. Numerical models for the tested specimens were developed and analyzed using SeismoStruct software. The analytical results show reasonable agreement with the experimental ones. The analysis not only correctly predicted the stiffness, load, and deformation at the peak, but also captured the post-peak softening as well. The analytical results showed that, in all cases, the ratio, experimental peak strength to the analytical one, was greater than 0.95.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.7
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• pp.569-576
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• 2003

The data link layer of Foundation Fieldbus provides both token-passing and scheduling services for periodic, time-critical and time-available data. This study developed an analytical model that evaluates the delay performance of urgent data when the data link layer of Foundation Fieldbus provides token-passing service. The validity of analytical model is verified using an experimental model that consists of network interface boards of Foundation Fieldbus. Comparison of analytical and experimental models shows that the analytical model can be utilized in the approximate analysis of the delay characteristics of time-critical data in the Foundation Fieldbus. The analytical model can also be used in the basic design stage of Foundation Fieldbus network system.

• Steel and Composite Structures
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• v.8 no.6
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• pp.441-455
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• 2008

This paper presents an effective hysteretic model for the prediction and evaluation of steel reinforced concrete member seismic performance. This model adopts the load-deformation relationship acquired from monotonic load tests and incorporates the double-pivot behavior of composite members subjected to cyclic loads. Deterioration in member stiffness was accounted in the analytical model. The composite member performance assessment control parameters were calibrated from the test results. Comparisons between the cyclic load test results and analytical model validated the proposed method's effectiveness.