• The Korean Journal of Ecology
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• v.19 no.2
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• pp.165-178
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• 1996

We investigated the role of competition in adaptation to varying water availability levels for two ecotypically-differentiated populations of Impatiens pallida found naturally in low- vs. high-water environments. In a greenhouse experiment, seedlings were grown in pure cultures at two densities (n=1 and 2 plants per pot) and in mixed cultures (n=2) under low-, medium- and high-water treatments. The two populations were shown to be genetically distinct across the range of environmental conditions in the greenhouse experiment, confirming previous findings. The two populations had similar morphological responses to density and water availability in pure cultures and mixtures, but the population from the high-water environment showed a greater growth response to high water availability than did the population from the low-water environment and the difference in growth between the two populations decreased from the high-water to low-water treatment. Relative competitive ability of two populations were compared under three different water treatments and two densities. Differential response to watering treatment and density were not reflected in a difference in relative competitive ability. Relative yield totals were significantly greater than 1 overall. The niche differentiation suggested by RYTs>1 may be responsible for the lack of differential competitive effects observed for populations in the three vatering treatments.

• Design & Manufacturing
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• v.13 no.4
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• pp.51-56
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• 2019

Due to industrial development, the importance of GD&T tolerance is growing day by day. Roundness measurement means the size deviated from the ideal circle. Roundness evaluation methods include LSCI, MZCI, MCCI, and MICI. Generally, A is used a lot at industrial evaluation. In this experiment, we studied the variations in table velocity, filter values, and detector angles, which can cause errors in roundness measurements. The measurement conditions were table speeds of 10, 30 and 60 mm/s, probe angles of 10, 20 and 30 degrees and frequency filter settings of 15, 150 and 500 upr and The number of experiments was measured 30 and the average value was chosen as a representative value. The hypothesis test showed that the p-value for the frequency filter was greater than 0.05, and the experiment rejected the null hypothesis and adopted the alternative hypothesis.

• Progress in Superconductivity
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• v.8 no.1
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• pp.122-126
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• 2006

This paper presents experimental and numerical investigation on heat generation of a bulk HTS for application to a 100 kWh Superconductor Flywheel Energy Storage System(SFES) bearing. An experimental device is manufactured to reproduce varying magnetic field conditions that a bulk HTS may experience during the operation of the 100 kWh SFES. The bulk HTS is directly cooled by a cryocooler while the heat is generated by the eddy currents created by varying magnetic fields induced by a coil. In order to design the cryocooling system for the 100 kWh SFES project, a preliminary experiment to investigate the actual cooling load variation under AC magnetic field has been carried out. In the experiment, two different copper holders were designed and tested. Several temperature sensors were installed on each component of the assembly and the temperatures were measured for several operating conditions of the 100 kWh SFES. The experimental investigation on the thermal response of the bulk HTS and its holder is considered to be a valuable step fur the successful materialization of a large-scale SFES.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.6
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• pp.135-142
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• 2001

Laboratory experiment was performed to evaluate the influence of mixing conditions to the strength of solidified sandy soils with cement. The major physical factors considered in this experiment were the fine particles content(<$\sharp200%$), cement content(%) and water-cement ratio, and unconfined compressive strength test was performed on the samples at 7 and 28 cured day. The results of tests shows that when the cement content is relatively low (7~10 percents) the fine content in the sandy soils is very important, but when cement content is high the water-cement ratio became more important. It was appeared that in the range of the cement content of 7~10 percents, about 20~30 percents of fine content to the total sample weight is the optimum condition to get the maximum strength. In the case of the cement content of 13 percents, the strength of sample was considerably affected by the water-cement ratio rather than the fine content. In this paper, empirical equations were also developed and evaluated to verify the relationship among three factors by the multi-regression analysis.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.2
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• pp.172-177
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• 1998

The culture filtrate of Streptomyces sp. B25, which was identified in this experiment, was tested for the control of tobacco mosaic virus (TMV) with the susceptible tobacco cultivar, NC 82, under the field conditions following the preliminary examination of its characters for TMV control. Control efficacy of the culture filtrate against TMV infection continued over 50% up to 6 days after treatment, and its systemic effect was about 30% of the direct effect. In field conditions control efficacy of the culture filtrate against TMV infection was 95.3 % at 2 weeks after TMV inoculation, and decreased to 58.3 % at 3 weeks after inoculation. Five fold-dilution of the culture filtrate showed about half of the control efficacy by the stock culture filtrate. Analysis of the antibiotic material responsible for the inhibition of TMV infection through nuclear magnetic resonance experiments revealed that the antibiotic is antimycin $A_1$, which is firstly reported as an anti-phytoviral antibiotic in this experiment.

• Journal of Embryo Transfer
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• v.14 no.2
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• pp.107-111
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• 1999

The present study was performed to evaluate the best electric fusion condition in nuclear transfer, Korean Native Cattle fibroblasts were used as nucleic donors. Oocytes from slaughterhouse were matured in vitro for 22 h and enucleated. Each individual cells were transferred into enucleated ocytes and reconstructed embryo were placed into the fusion chamber. In experiment 1, pulse were performed by altering pulse duration at 1. 75kv/cm, 1 time. When pulse duration is 30$mutextrm{s}$, fusion and development rates is higher than other conditions. In experiment 2, the effect of different pulse number were studied at the pulse duration 30$mutextrm{s}$ and the same pulse intensity. When pulse number was one, fusion rates were higher than other conditions. The fused embryos were moved to culture medium and assessed their development to blastocyst. These results showed that best fusion condition was 30$mutextrm{s}$ and one time. And the fibroblasts derived from Han Woo can be reprogrammed by nuclear transplantation and develop subsequently in vitro.

• Structural Engineering and Mechanics
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• v.37 no.3
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• pp.331-349
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• 2011

This study investigates the use of a vibration correlation technique (VCT) to identify the buckling load of a rectangular thin plate. It is proposed that the buckling load can be determined experimentally using the natural frequencies of plates under tensile loading. A set of rectangular plates was tested for natural frequencies using an impact test method. Aluminum and stainless steel specimens with CCCC, CCCF and CFCF boundary conditions were included in the experiment. The measured buckling load was determined from the plot of the square of a measured natural frequency versus an in-plane load. The buckling loads from the measured vibration data match the numerical solutions very well. For specimens with well-defined boundary conditions, the average percentage difference between buckling loads from VCT and numerical solutions is -0.18% with a standard deviation of 5.05%. The proposed technique using vibration data in the tensile loading region has proven to be an accurate and reliable method which might be used to identify the buckling load of plates. Unlike other static methods, this correlation approach does not require drawing lines in the pre-buckling and post-buckling regions; thus, bias in data interpretation is avoided.

• Nuclear Engineering and Technology
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• v.33 no.6
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• pp.638-651
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• 2001

The present study is to assess the applicability of the best-estimate thermal-hydraulic code, MARS 1.4, for the analysis of thermal-hydraulic behavior in PWRs during natural circulation conditions. The code simulates a natural circulation test, BETHSY test 4. la, which was conducted on the integral test facility of BETHSY. The test represented the cooling states of the primary cooling system under single-phase natural circulation, two-phase natural circulation and the reflux condensation mode with conditions corresponding to the residual power, 2% of the rated core power value and 6.8 MPa at the secondary system. Based on MARS 1.4 calculations, the major thermal-hydraulic behaviors during natural circulation are evaluated and the differences between the experimental data and calculated results are identified. The calculated results show generally good behavior with regard to the experimental results; the region of single-phase natural circulation is 100-92% of the initial mass inventory, two-phase natural circulation is 84-63 %, and the reflux condensation mode occurred below 58 %. U-tubes empty and the core uncovery are obtained at 39 % and 34 % of the initial mass inventory, respectively.

• Journal of the Ergonomics Society of Korea
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• v.21 no.1
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• pp.95-112
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• 2002

Two experiments were carried out to compare the suitability in visual tasks between cathode-ray tube (CRT) and thin film transistor-liquid crystal display (TFT-LCD). In the first experiment, the subjects were requested to detect pre-assigned target words or icons among distracters presented under time-invariant (static) image mode. The subjects' visual performance and fatigue were assessed while carrying out search tasks with dim and bright ambient light conditions. Significant interaction effects were found among displays, task types, and ambient light conditions. Due to visual fatigue, the subjects' accommodative power decreased in the end of task and the degradation was more significant for the CRT users and under bright ambient light. IN the second experiment, the subjects performed information processing task with time-varying road signs at a driving simulator to assess interaction effects between display types and changing speed of dynamic image. The perception time using TFT-TCD was shorter under slow image change while that of CRT was shorter rapid image change. Findings from this study suggest that, to improve visual task performance, users should carefully select their visual display type depending on the task to be performed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.208-215
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• 2001

An experimental method to investigate the dynamic charasteristics of buoys in extreme environmental condition is established. Because the buoy model requires a resonable size for accurate experiment, the test condition in model basin that satisfies the similarity law is hardly met with capability of test facilities. It is suggested that the linear wave component that is unable to satisy similarity is separated with others. The model experiment can be carried out with mitigated condition for the linear wave components while others including wave drift, current and wind are keeping the similarities. Then the result is extrapolated to give the dynamic behavior of buoys in extreme condition because linear wave component is soley responsible to oscillatory buoy motion and other environmental components are applied as a initial tension. the similarity for current and wind conditions is viewed as equivalence of restoring forces. the validity of proposed method is examined with different types of standard ocean buoys and it indicates that the linearity of measured characteristics is assured with a limitation of resonable distance between test and estimated wave conditions.