• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.211-215
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• 1989

This paper presents the thermal analysis of EHV OF cable accessories using FEM. The governing equation about the temperature in the cable accessories is induced by the energy balance equation. Since the temperature distribution is a function of space and time, the weighted residual method is adopted for FEM formulation. The difference approximation is used to treat the time differential term in the element equation. Automatic mesh generation which save time and labor is introduced for the data input process. It will be expected that the following thermal analysis result will be very useful to cable accessories design.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.221-237
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• 2015

An integrated method is proposed for structural nonlinear damage detection based on time series analysis and the higher statistical moments of structural responses in this study. It combines the time series analysis, the higher statistical moments of AR model residual errors and the fuzzy c-means (FCM) clustering techniques. A few comprehensive damage indexes are developed in the arithmetic and geometric mean of the higher statistical moments, and are classified by using the FCM clustering method to achieve nonlinear damage detection. A series of the measured response data, downloaded from the web site of the Los Alamos National Laboratory (LANL) USA, from a three-storey building structure considering the environmental variety as well as different nonlinear damage cases, are analyzed and used to assess the performance of the new nonlinear damage detection method. The effectiveness and robustness of the new proposed method are finally analyzed and concluded.

• Steel and Composite Structures
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• v.16 no.6
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• pp.595-609
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• 2014

The paper is reporting some comparisons between experimental and numerical results in terms of failure mode, failure time and ballistic properties of mild steel sheet. Several projectile shapes have been considered to take into account the stress triaxiality effect on the failure mode during impact, penetration and perforation. The initial and residual velocities as well as the failure time have been measured during the tests to estimate more physical quantities. It has to be noticed that the failure time was defined using a High Speed Camera (HSC). Thanks to it, the impact forces (average and maximum level), were analyzed using numerical simulations together with an analytical description coupled to experimental observations. The key point of the model is the consideration of a shape function to define the pulse loading during perforation.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.99-106
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• 2002

For the development of a ultra-precision CNC polishing system including on-machine measurement system, we study a corrective polishing algorithm. We calculated unit removal profiles for various flat type polishing tools and polishing tool positions. Using these results we simulate the corrective polishing process based on dwell time control. We calculate dwell time distributions and residual error of the polishing simulation method and the FFT calculation method. We test corrective polishing algorithm with an optical glass. The target removal shape is a sine wave that has amplitude 0.3 micro meters. We find this polishing process has a machining resolution of nanometer order and is effective for sub-micrometer order machining. This result will be used for the software development of the CNC polishing system.

• Journal of Preventive Medicine and Public Health
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• v.24 no.1 s.33
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• pp.29-36
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• 1991

A multiple regression analysis using ordinary least square (OLS) is frequently used for the projection of health expenditure as well as for the identification of factors affecting health care costs. Data for the analysis often have mixed characteristics of time series and cross section. Parameters as a result of OLS estimation, in this case, are no longer the best linear unbiased estimators (BLUE) because the data do not satisfy basic assumptions of regression analysis. The study theoretically examined statistical problems induced when OLS estimation was applied with the time series cross section data. Then both the OLS regression and time series cross section regression (TSCS regression) were applied to the same empirical da. Finally, the difference in parameters between the two estimations were explained through residual analysis.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.1
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• pp.100-106
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• 1992

The objective of this study is to develop a real-time runoff forecasting model considering stochastic component. The model is composed of deterministic and stochastic components. Simplified tank model was selected as a deterministic runoff forecasting model. The time series of estimation residual resulting from the tank model simulation was analyzed and was best suited to the second-order autoregressive model. ARTANK model which combined the tank model with the autoregressive process was developed. And it was applied to a BANWEOL basin for validation. The simulation results showed a good agreement with the observed field data.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.144-151
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• 2002

Future wireless communication systems are expected to provide a broad range of multimedia services in which the asymmetry of traffic load between uplink and downlink is a significant feature. The rode division multiple access system with tune division duplex mode (CDMA/TDD) is a good solution to cope with the traffic asymmetry problem. However. the TDD system is subject to inter-cell interference compared to frequency division duplex (FDD) system. Since both uplink and downlink share the same frequency in TDD. uplink and downlink may interfere each other especially when neighboring cells require different rates of asymmetry. Thus, time slot allocation for tells is an important issue in TDD. In this paper. we propose a genetic algorithm based time slot allocation scheme which maximizes the residual system capacity. The proposed scheme allows that each cell employ different level of uplink/downlink asymmetry and satisfies the interference requirement.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.43-50
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• 2005

This test was performed to evaluate the change of the unconfined compressive strength, strength parame¡?ters which resulted from direct shear test and oil residue percents analyzed by GC-MS as time lapse, oil addition. Unconfined compression strength of $10\%$ kerosene added by weight of dry soil recovered as time passed. In the case of $5\%$ kerosene added, the strength recovered as much as clean clayey soil after about 50 days passing. For the case of diesel added, the recovery of unconfined compressive strength was not shown even though about 60 days passed. The strength parameters (c, $\psi$) of kerosene added not changed but for diesel added, the cohesion was very decreased as diesel addition increased. Residual percent of kerosene in the soil was less than that of diesel as time passed.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.561-562
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• 2003

pH varies in the oral environment and on tooth surfaces. The surface of a plaque covered resinous restoration has a low pH. In human dental plaque a number of acids are produced by bacterial metabolism. The predominant acids are acetic, propionic and lactic acids. These acids induced a surface swelling of restorative resin. The swelling cause formation of pores inside the resin matrix from which organic substances can be released, resulting in a mass loss. The purpose of this study was to qualitatively and quantitatively analyse the leached monomers of dental composites after storage in acetate buffer solution as a function of time by means of high performance liquid chromatography(HPLC) / mass spectrometer and further determine whether pH and time has any influence on the degradation behavior of composite restoration.(omitted)

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.37-45
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• 2007

A lot of conventional algorithms has tried to cancel the Residual Frame Synchronization Error (RFSE), which causes the performance degradation of channel estimation when using interpolation in lattice-type pilot-aided Time Division Duplex (TDD) OFDM systems. Among them, a pre- and post-compensation method has been attractive to eliminate the effects of RFSE, providing good performance but requiring high computational complexity. In this paper we propose a new method which lowers computational costs by adjusting the starting point of TDD OFDM systems' FFT window in order to compensate for the RFSE. For the performance verification, we apply the proposed method to IEEE 802.16e standard and also estimate additionally required computational power of it compared to the pre- and post-compensation method. Simulation and implementation results show that the proposed algorithm has performance similar to the conventional method and is very efficient with low power implementation, requiring only 4.9 % of the power which the conventional method needs additionally.