• Journal of Broadcast Engineering
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• v.21 no.1
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• pp.76-86
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• 2016

This study was investigated whether the perceived depth was changed depending on the measurement methods. In the method of direct comparison, virtual object with one of the various binocular disparities was presented in the frontal space with LEDs which were used for depth estimation for a binocular stimulus, while in the method of indirect comparison, visual object was presented in the frontal space but the LEDs were placed rightward at the angle of 45 degree from the mid-sagittal line. In these experimental setup, the depth of binocular stimulus was directly matched that of LED in direct comparison condition. In indirect comparison condition, however, observer estimated the depth of binocular stimulus, turned one's head rightward to the array of LEDs and turned on the LED which was supposed to be the same depth as binocular stimulus. Additionally, it was investigated whether the perceived depth was different depending on observer's stereo acuity. The results showed that perceived depths measured in the direct comparison were more similar to the depth predicted from geometry than those in the indirect comparison, and that the perceived depths from observers with high stereo acuity were similar to the predicted depth from geometry those from observers with low stereo acuity. These results indicated that stereoscopic depths of the binocular stimuli would vivid and compelling when binocular stimuli was simultaneously presented with real objects in the same visual space, like a mixed reality.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.1-11
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• 2003

In order to measure aperture variation dependent on normal stress and to characterize on relationship between aperture variation and hydraulic conductivity this study measured apertures of rock fractures under a high resolution confocal laser scanning microscope (CLSM) with application of five stages of uniaxial normal stresses. From this method the response of aperture can be continuously characterized on one specimen by different loads of normal stress. The results of measurements showed a rough geometry of fracture bearing non-uniform aperture. They also revealed different values of aperture variations according to the load stages on each position along a fracture due to the fracture roughness. Laboratory permeability tests were also conducted to evaluate the changes of permeability coefficients related to the aperture variations by different loads. The results of permeability tests revealed that the hydraulic conductivity was not reduced at a fixed rate with increase of normal load. Moreover, the rates of aperture variations did not match to those of hydraulic conductivity. The hydraulic conductivity calculated in this study did not follow the cubic law, representing that the parallel plate model is not suitable to express the fracture geometry corresponding to the results of aperture measurements under the CLSM.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.522-529
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• 2014

Circulating fluidized bed system consists of SEWGS reactor - lower loop seal - regeneration reactor - riser - cyclone - upper loop seal has been used for solid circulation between the SEWGS reactor and the regeneration reactor in a SEWGS system for pre-combustion $CO_2$ capture. A vertical type lower loop seal has been used in current system but this lower loop seal requires high gas flow rate through the lower loop seal for fluidization and smooth solid circulation, and consequently, causes slugging behavior sometimes. To overcome these disadvantages, inclined type lower loop seal was proposed by this study. Solid circulation characteristics with change of lower loop seal geometry were measured and compared in a bubbling - bubbling - riser type circulating fluidized bed using $CO_2$ absorbent (P-78) as bed material at ambient temperature and pressure. We could conclude that the inclined lower loop seal is better than the vertical type lower loop seal from the viewpoints of minimum flow rate requirement for stable solid circulation and solid height change during solid circulation.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.243-251
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• 2005

The distribution of temperature of flip chipped device with peripheral solder bump array was measured with variables, such as the locations and geometries of heater, the size of device, the size of passivation opening. The highest temperature was measured with the larger device, $3.0(mm)\times3.0(mm)$, which has the smallest heater at the center of device and the circular passivation opening. For 2 (watts) power input, the device shows the highest temperature of about $110(^{\circ}C)$. In contrast, the smaller device, $1.5(mm)\times1.8(mm)$, shows that of $90(^{\circ}C)$. In addition to the size effect, the increase of passivation opening size decreased the maximum temperature by about $10(^{\circ}C)$. From the measurement, the temperature of device could be controlled with the size and geometry of heater, the size of device and the size and geometry of passivation opening.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.619-628
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• 2009

To predict the time-dependent behavior of concrete structures, the models which describe the time-dependent characteristics of concrete, i.e. creep and shrinkage are required. However, there must be significant differences between the displacements that are obtained using the given creep and shrinkage models and the measured displacements, because of the uncertainties of creep and shrinkage model itself and those of environmental condition. There are some efforts to reduce these error or uncertainties by using the model which are obtained from creep test for the concrete in construction site. Nevertheless, the predicted values from this model may be still different from the actual values due to the same reason. This study aimed to propose a method of estimating the creep coefficient from the measured displacements of concrete structure, where creep model uncertainty factor was considered as an error factor of creep model. Numerical validation for double composite steel box and concrete beam showed desirable feasibility of the presented method. Consideration of the time-dependent characteristics of creep as one of the error factors make it possible to predict long-term behaviors of concrete structures more realistically, especially long-span PSC girder bridges and concrete cable-stayed bridges of which major problem is the geometry control under construction and maintenance.

• The Mathematical Education
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• v.57 no.3
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• pp.197-213
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• 2018

Descriptive problems can be used to grow student's ability of thinking logically and creatively, because it shows if the students had a reasonable way of thinking. Rate of descriptive problems is increasing in middle and high school exams. However, students in middle and high schools are generally used to answering multiple-choice or short-answer questions rather than describing the solving process. The purpose of this paper is to gain a theoretic ground to increase the rate of descriptive problems. In this study, students were to solve some multiple-choice problems, and after a few weeks, to solve the problems of same contents in the form of descriptive problems which requires the students to write the solving process. The difference of the scores were measured for each problems to each students, and students were asked what they think the reason for rise or fall of the score is. The result is as follows: First, average scores of 7 of 8 problems used in this study had fallen when it was in descriptive form, and for 5 of them in the rate of 11.2%~16.8%. Second, the main reason of falling is that the students have actual troubles of describing the solving process. Third, in the case of rising, the main reason was that partial scores were given in the descriptive problems. Last, there seems a possibility gender difference in the reason of falling. From these results, followings are suggested to advance the learning, teaching and evaluation in mathematics education: First, it has to be emphasized enough to describe the solving process when solving a problem. Second, increasing the rate of descriptive problems can be supported as a way to advance the evaluation. Third, descriptive problems have to be easier to solve than multiple-choice ones and it is convenient for the students to describe the solving process. Last, multiple-choice problems have to be carefully reviewed that the possibility of students' choosing incorrect answer with a small mistake is minimal.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.363-367
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• 1993

A retrospective analysis was peformed on 42 patients with carcinoma of the uterine cervix who were treated with external beam (EB) radiation therapy alone at the Department of Therapeutic Radiology, Seoul National University Hospital from March 1979 to December 1988. After whole pelvic field irradiation of 50Gy, all the patients received additional booster dose of 12-22Gy to the primary tumor Thirty one received EB radiotherapy alone because of poor geometry for intracavitary application,5 because of medical problems and 6 because of other reasons. Five year locoregional control rate and five year survival rate were $34.5\%\;and\;35.4\%,$ respectively. Five year survivals were $66.7\%,\;36.4%,\;32.8\%\;and\;25.0\%$ for stage IIA, IIB, IIIB and IVA, respectively. The response one month after treatment well correlated with prognosis. The incidence of grade 2 and 3 complication was $12\%\;and\;10\%,$ respectively. There was tendency of increased complication with advanced stage.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.228-233
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• 2013

It has been continuously generated the requirement for the replacement of the main components such as a steam generator due to the deterioration of the nuclear power plant all around the world. Also, a large amount of radioactive metal was generated during the decommissioning in a short period. It is required to make an accurate measurement of the residual radioactivity for recycling the metal waste for releasing from regulatory control. In planning the measurement procedures, the influence of geometry, self-absorption, density and other relevant factors on the representativeness of the measurements should be considered for the decommissioning metal waste. In this study, the method for measurement procedures, the source term evaluation, the ways to secure representative samples, the measurement device for wide area and the self-absorption correction factors for different density were evaluated. The metal samples for measurement were prepared for securing the simple geometry and representative by melting process. The developed correction method for measuring the radioactivity a variety density of metal waste could improve the reliability of the evaluation results for clearance.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.847-859
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• 2021

Recently, as the number of high-resolution satellite SAR images increases, the demand for precise matching of SAR imagesin change detection and image fusion is consistently increasing. RMSE (Root Mean Square Error) values using GCPs (Ground Control Points) selected by analysts have been widely used for quantitative evaluation of image registration results, while it is difficult to find an approach for automatically measuring the registration accuracy. In this study, a feasibility analysis was conducted on using the FSIM (Feature Similarity) index as a measure to evaluate the registration accuracy. TerraSAR-X (TSX) staring spotlight data collected from various incidence angles and orbit directions were used for the analysis. FSIM was almost independent on the spatial resolution of the SAR image. Using a single SAR image, the FSIM with respect to registration errors was analyzed, then use it to compare with the value estimated from TSX data with different imaging geometry. FSIM index slightly decreased due to the differencesin imaging geometry such as different look angles, different orbit tracks. As the result of analyzing the FSIM value by land cover type, the change in the FSIM index according to the co-registration error was most evident in the urban area. Therefore, the FSIM index calculated in the urban was mostsuitable for determining the accuracy of image registration. It islikely that the FSIM index has sufficient potential to be used as an index for the co-registration accuracy of SAR image.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.23-31
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• 2018

In the present work, the thrust and torque of multicopter propellers in hovering are predicted based on BET method. The geometry information of the propellers is obtained using a three dimensional scanner and the airfoil section is extracted using CATIA. EDISON CFD is adopted to calculate the drag and lift of airfoil at a given geometry and flow conditions and then thrust is calculated with respect to a given RPMs based on BET. Two simulations with laminar and turbulent flows are considered. The predicted value is compared with the performance data from the Product Company and results from JavaProp software, which is used in the design and prediction of propellers. In the case of a 9-inch propeller, the thrust from the product company is corresponding to the results between the laminar and turbulent flow conditions. In the 16-inch case, the predicted thrust at turbulent flow conditions conformed well with reference one. The predicted torque shows a big difference with the reference data.