• Journal of Powder Materials
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• v.17 no.3
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• pp.197-202
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• 2010

Low temperature degradation behavior in yttria stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics was microscopically observed from the phase contrast between monoclinic surface and tetragonal matrix. The degradation behavior was dependent on the surface treatment of sintered Y-TZP, even if the sintering history is same. In the mirror polished specimen, the monoclinic layer appeared in a uniform thickness from the surface. On the contrary, for the specimen with coarse scratch, the thickness of degraded surface was more than double especially from the coarse scratch. Since the scratch results in local deformation, the residual stress should be induced around the scratch. With the transformation from tetragonal to monoclinic, the volume expansion exerts a stress on a neighboring grains and promotes a successive phase transformation. Such a autocatalytic effect can be triggered from the part of coarse scratch.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.1
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• pp.40-47
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• 2010

This paper presents a simultaneous localization and mapping (SLAM) of an indoor hallway environment using Rao-Blackwellized particle filter (RBPF) along with a line segment as a landmark. Based on the fact that fluent line features can be extracted around the ceiling and side walls of hallway using vision sensor, a horizontal line segment is extracted from an edge image using Hough transform and is also tracked continuously by an optical flow method. A successive observation of a line segment gives initial state of the line in 3D space. For data association, registered feature and observed feature are matched in image space through a degree of overlap, an orientation of line, and a distance between two lines. Experiments show that a compact environmental map can be constructed with small number of horizontal line features in real-time.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.36-40
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• 2010

In this paper, the well-known LOB-based emitter localization using linear LSE algorithm is numerically implemented and the heuristic guidelines for the parameter values to achieve 1% RMS error are presented. In the simulation, we changed the total observation durations for LOB measurements, time interval between successive LOB measurements and sensor trajectories. The effects of the time interval of LOB measurements, the time duration of the LOB measurements and the angle of flight path arc on the performance are illustrated. The dependence of the performance on the various parameters is investigated and rule-of-thumbs for the parameter values corresponding to 1% RMS error are presented for each simulation condition.

• International Journal of Railway
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• v.3 no.1
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• pp.1-6
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• 2010

The steel plate-girder bridges with concrete gravity piers have possibilities of overturning by lateral inertial force which can be reproduced by sudden earthquake attack. This paper explores an overturning mechanism of existing concrete gravity pier onto the sandy soil in the event of lateral push-over load by in-situ experimental observation. The in-situ push-over experiment for pier with earth anchors between spread footing and rock beds exhibits a reasonable enhancement of ductility against overturning. In unanchored system, a flexural crack at cold joint of concrete pier is not developed because of the over-turning of the pier. This leads a global instability (rotation) of pier-footing system with relatively low stresses in pier itself. While a lateral load is persistently increased in anchored system, the successive flexural cracking failure at cold joint is observed even after the local shear failure of soil due to redistribution of stress equilibrium between soil and pier structure as long as a tensile action of anchor cable is active.

• Journal of Power Electronics
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• v.17 no.2
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• pp.476-489
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• 2017

Under partial shading conditions (PSCs), multiple maximums may be exhibited on the P-U curve of string inverter photovoltaic (PV) systems. Under such conditions, heuristic methods are invalid for extracting a global maximum power point (GMPP); intelligent algorithms are time-consuming; and model-based methods are complex and costly. To overcome these shortcomings, a novel hybrid MPPT (MPF-IP&O) based on a model-based peak forecasting (MPF) method and an improved perturbation and observation (IP&O) method is proposed. The MPF considers the influence of temperature and does not require solar radiation measurements. In addition, it can forecast all of the peak values of the PV string without complex computation under PSCs, and it can determine the candidate GMPP after a comparison. Hence, the MPF narrows the searching range tremendously and accelerates the convergence to the GMPP. Additionally, the IP&O with a successive approximation strategy searches for the real GMPP in the neighborhood of the candidate one, which can significantly enhance the tracking efficiency. Finally, simulation and experiment results show that the proposed method has a higher tracking speed and accuracy than the perturbation and observation (P&O) and particle swarm optimization (PSO) methods under PSCs.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.513-521
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• 2015

In the processing of ocean color remote sensing data, spatio-temporal binning is crucial for securing effective observation area. The validity determination for given source data refers to the information in Level-2 flag. For minimizing the stray light contamination, NASA OBPG's standard algorithm suggests the use of large filtering window but it results in the loss of effective observation area. This study is aimed for quality improvement of ocean color remote sensing data by recovering/extending the portion of effective observation area. We analyzed the difference between MODIS/Aqua standard and modified product in terms of chlorophyll-a concentration, spatial and temporal coverage. The recovery fractions in Level-2 swath product, Level-3 daily composite product, 8-day composite product, and monthly composite product were $13.2({\pm}5.2)%$, $30.8({\pm}16.3)%$, $15.8({\pm}9.2)%$, and $6.0({\pm}5.6)%$, respectively. The mean difference between chlorophyll-a concentrations of two products was only 0.012%, which is smaller than the nominal precision of the geophysical parameter estimation. Increase in areal coverage also results in the increase in temporal density of multi-temporal dataset, and this processing gain was most effective in 8-day composite data. The proposed method can contribute for the quality enhancement of ocean color remote sensing data by improving not only the data productivity but also statistical stability from increased number of samples.

• Journal of Ecology and Environment
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• v.31 no.1
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• pp.9-15
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• 2008

Growth and reproduction of Palaemon serrifer were described and analyzed in a population inhabiting tide pools in warm temperate waters in Korea. The water temperature varied greatly in the tide pools, ranging from 8$^{\circ}C$ to 27.8$^{\circ}C$ Population structure and growth were investigated using size frequency distribution data collected from January to December 2003. Sex ratios fluctuated, but were almost equal during the breeding period. Growth was continuous and size increased gradually throughout the year. Adult females were larger and grew faster than males. von Bertalanffy growth parameters for a one-year sample of females and males were estimated as $L_{i\ddot{A}}$ = 11.32, K = 0.311, $t_0$ = -0.4115 and $L_{i\ddot{A}}$ = 8.36, K = 0.228, $t_0$ = -0.9693 respectively. Breeding was seasonal, starting in May, peaking in August, and finishing by the end of August. The species showed continuous production of successive broods. Laboratory observation showed that females with embryos near hatching had ovaries filled with vitellogenic oocytes ready for spawning. The reproductive output (effort) of each female (mean number of eggs: $552{\sim}1355$) was not high. The mean embryo volume, $0.078mm^3$, is relatively small, indicative of low energy allocation to each embryo. Recruitment of juveniles was closely linked to the breeding period, beginning in September.

• Communications for Statistical Applications and Methods
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• v.15 no.4
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• pp.517-530
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• 2008

In this paper we introduce a time series model using the triangle fuzzy numbers in order to construct a statistical relation for the data which is a sequence of observations which are ordered in time. To estimate the proposed fuzzy model we split of a universal set includes all observation into closed intervals and determine a number and length of the closed interval by the frequency of events belong to the interval. Also we forecast the data by using a difference between observations when the fuzzified numbers equal at successive times. To investigate the efficiency of the proposed model we compare the ordinal and the fuzzy time series model using examples.

• Korean Journal Plant Pathology
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• v.10 no.4
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• pp.284-291
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• 1994

In order to establish an appropriate spray schedule to reduce the infection, 11 kinds of chemicals were tested for their properties on the inhibition of spore germination at the surface of apple fruits and the duration of the inhibitory effect after spray of each chemical was examined from late June to early September with basically 10 day intervals. Actual control efficacy of each chemical by the 8 successive spray and the patterns of waterborne spore dispersals during that periods were also examined. Combining those results with the meteorological observation data, actual control efficacy of each chemical in the given periods could be estimated. It was revealed that folpet, Brodeaux mixture, mancozeb, oxine copper and imminoctadine-triacetate could be used at any time during the possible infection periods. Captan and dithianon could also be used except the rainy season due to the short duration of inhibitory efficacy against spore germination under heavy rain. However, the usefulness of propineb, benomyl and chlorothalonil against the apple white rot could not be demonstrated in this experiment. Thiram, even though has not been used for apple white rot, can also be used before or after the rainy season to control not only white rot but also alternaria blotch.

• Geophysics and Geophysical Exploration
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• v.19 no.2
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• pp.91-96
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• 2016

From the Earth's polar motion time series (IERS 08 C04, since 1981), after removal of seasonal variation by band-pass filtering, we acquired Earth's free Eulerian motion (Chandler wobble) time series. By successive least square error fittings on it, we analyzed amplitude and phase variation of Chandler wobble. We attempted to identify any precursory behavior of the pole before large earthquakes but only to fail. Unlike Smylie's conjecture there was no appreciable motion of the Earth's pole detected at around the each times of recent six largest earthquakes of magnitude over 8.5.