• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1007-1012
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• 2007

A novel Michelson interferometer controlled with a feedback circuit(MIFC) has been developed and its performance has been evaluated. This new interferometer can measure the displacement of the sample by directly reading the feedback bias applied to the PZT whose piezoelectric characteristic is known. The experimental result showed that the step height the silicon membrane measured by using MIFC was actually same with the value measured by SEM, which confirms that MICS is an easy and accurate method for the nano-scale displacement measurement.

• Journal of the Korean Society of Visualization
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• v.21 no.2
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• pp.45-54
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• 2023

In the present study, we propose new type of a spinning disk reactor(SDR) with high performance and very convenient structure to make a large scale equipment from lab-scale than the conventional one. A split-disk experimental equipment, based on new type of spinning disk reactor, has been developed to generate an energy to break a bulk of injected gas into smaller gas bubble. Several cases of an experimental observation make it to confirm that a bulk of injecting gas could be continuously break into smaller bubbles. It shows the feasibility to make a scale-up of SDR by using the characteristic of Taylor-Proudman column in rotating flow. A theoretical study on single phase liquid flow is given to predict a liquid induced shear stress, which make the present study to be self-containment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.1-5
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• 2010

This paper deals with a method to measure the thickness of scale-layer, iron oxide formed on the surface of the rolling steel, using a dielectric lens antenna. The dielectric lens antenna has an independent characteristic with the frequency in the X-band and changes the spherical wave radiated from a horn antenna into a plane wave at the focusing point. Using this concept, we regard a scale-layer on the rolling steel as a dielectric-PEC(Perfect Electric Conductor) layer and apply a theoretical analysis of the normal-incident plane wave. To reduce the phase error arising from the use of the dielectric lens antenna, this paper utilizes a regression process algorithm. In comparison with the conventional iteration algorithm, the present algorithm led to a unique solution for the thickness of the scale-layer.

• Anxiety and mood
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• v.10 no.2
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• pp.170-175
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• 2014

Objective : The aims of this study was to evaluate relationship between body dissatisfaction, personality characteristic, and stress in young adults. Methods : One hundred and ninety five young, healthy, and normal participants filled out all 3 types of self-reported questionnaire, the Body Dysmorphic Disorder Examination-Self Report (Korean version of BDDE-SR ; K-BDDE-SR), Neuroticism, Extraversion, Openness-Five Factor Inventory (NEO-FFI) and Stress Scale of Korean version of the Depression Anxiety Stress Scale (K-DASS-21). Results : Out of the 195 participants, 30% (n=59) was male and 70% (n=136) was female. There was no statistical difference between high K-BDDE-SR group (K-BDDE-SR score 75 percentile or higher, n=50) and low K-BDDE-SR group (K-BDDE-SR score below than 75 percentile, n=145) in terms of weight, height, and BMI. In high K-BDDE-SR group, neuroticism was significantly higher than low K-BDDE-SR group, and extraversion, agreeableness, conscientiousness were significantly lower than low K-BDDE-SR group. Also, level of stress in high K-BDDE-SR group was significantly higher than low K-BDDE-SR group. Conclusion : Our study revealed that individual's with more body dissatisfaction were more neurotic and stressful. Thus, body dissatisfaction and diverse psychiatric diseases should be considered in treating neurotic and stressful young adults.

• Journal of the Korean Geographical Society
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• v.37 no.1
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• pp.93-110
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• 2002

The purpose of this study is to analyse the change and characteristic of agricultural land use for the mountainous village which was linked to the development of arable land in the historic process as the case study on Yowon-village, Gyeongbuk province. The findings are summarized as fellows. First, most of arable land development had been developed from the late 16th century to the late 19th century and in the 1960s. A rice field was developed at the valley containing water resource and a dry field at the land close to a village before 1960 and at the gently sloped and wide hill after 1960. Second, the crops cultivated before the introduction of commercial agriculture were potato, foxtail millet, bean. After the 1970s, The vegetable, red pepper, tobacco were commercially cultivated. Third, the main group of land use change(choice of crops) result from effort of the inhabitant The significance of this study are as follows, explaining the change and characteristic of agriculture land use for the mountainous village which was linked to the development of arable land, studying as the case on small-scale village.

• Smart Structures and Systems
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• v.20 no.6
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• pp.683-696
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• 2017

In this study, the reliability of nonlinear ultrasonic modulation based fatigue crack detection is improved using a feature-level data fusion approach. When two ultrasonic inputs at two distinct frequencies are applied to a specimen with a fatigue crack, modulation components at the summation and difference of these two input frequencies appear. First, the spectral amplitudes of the modulation components and their spectral correlations are defined as individual features. Then, a 2D feature space is constructed by combining these two features, and the presence of a fatigue crack is identified in the feature space. The effectiveness of the proposed fatigue crack detection technique is experimentally validated through cyclic loading tests of aluminum plates, full-scale steel girders and a rotating shaft component. Subsequently, the improved reliability of the proposed technique is quantitatively investigated using receiver operating characteristic analysis. The uniqueness of this study lies in (1) improvement of nonlinear ultrasonic modulation based fatigue crack detection reliability using feature-level data fusion, (2) reference-free fatigue crack diagnosis without using the baseline data obtained from the intact condition of the structure, (3) application to full-scale steel girders and shaft component, and (4) quantitative investigation of the improved reliability using receiver operating characteristic analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.1-11
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• 2020

In this study, a hot-firing test of a lab-scale gel rocket motor using liquid kerosene and gelled kerosene as fuel was performed in order to analyze the discrepancy of the static and dynamic pressure between the two fuels. The static pressure, characteristic velocity, and characteristic velocity efficiency of the liquid kerosene and gelled kerosene did not show any significant difference. However, in the case of dynamic pressure characteristics, the pressure oscillation amplitude in a specific high frequency region of the gelled kerosene demonstrated a significantly higher amplitude than liquid kerosene case. This is considered to be the effect of an intrinsic combustion mechanism of the gel propellant, and it can be postulated that this may act as a dominant factor influencing the high frequency combustion instability of the gel rocket motor.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.53.1-53.1
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• 2018

During a major solar eruption, the erupting plasma is possibly out of the equilibrium ionization state because of its rapid heating or cooling. The non-equilibrium ionization process is important in a rapidly evolving system where the thermodynamical time scale is shorter than the ionization or recombination time scales. We investigate the effects of non-equilibrium ionization on EUV and X-ray observations by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory and X-ray Telescope (XRT) on board Hinode. For the investigation, first, we find the emissivities for all the lines of ions of elements using CHIANTI 8.07, and then we find the temperature responses multiplying the emissivities by the effective area for each AIA and XRT passband. Second, we obtain the ion fractions using a time-dependent ionization model (Shen et al. 2015), which uses an eigenvalue method, for all the lines of ion, as a function of temperature, and a characteristic time scale, $n_et$, where $n_e$ and t are density and time, respectively. Lastly, the ion fractions are multiplied to the temperature response for each passband, which results in a 2D grid for each combination of temperature and the characteristic time scale. This is the set of passband responses for plasma that is rapidly ionized in a current sheet or a shock. We investigate an observed event which has a relatively large uncertainty in an analysis using a differential emission measure method assuming equilibrium ionization state. We verify whether the observed coronal plasmas are in non-equilibrium or equilibrium ionization state using the passband responses.

• Journal of architectural history
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• v.16 no.6
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• pp.7-26
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• 2007

This article is about restoring the wooden pagoda which located in Silsangsa Temple after historical research. The process of this study, first of all, the theoretical study was considered about similar examples of wooden pagoda and gilt-bronze pagoda in Gorye period and wooden pagoda in contemporary period. After that, the study was established by the present condition of Silsangsa wooden pagoda site, the characteristic of Silsangsa wooden pagoda, the form of arrangement, the scale and height. Finally, considering those studies, the wooden pagoda designed in detail. This restoring design tried to follow the inference in that time. Moreover, the design tried to involve the elements of characteristic of region and Silsangsa wooden pagoda. Therefore, the research establish period of Silsangsa wooden pagoda in Gorye period. Locally, it considered both elements of Silla and Baeckje. The arrange form of restoring wooden pagoda was freestyle arrangement that had two main building of a temple and one middle pagoda. The idea of structure was to establish of double Core system. This system inferred from the system of building structure in ancient wooden pagoda and middle and modern age of multistory wooden construction. According to measurement of foundation stone, the scale of restoring wooden pagoda followed the skill of Tang-scale. The connection structure of each floor followed laminated structure which was the general form of log frame in that time. After study of foundation's condition, the present writer deseeded to have restoring the wooden pagoda 9 stories tall. The final aim was to depend on the structural intuition of the present writer, the writer tried to restore beautiful wooden pagoda according to in those days which is solution for contradiction of unclear point. So, it could be make out a plane of restoring wooden pagoda.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.267-274
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• 2016

Sewerage supply in rural community is the important for water quality protection of water system such as river, lake and wetland. And characteristic of small scale wastewater system that have wide range of inflow and concentration in sewage should be considered for stable operation of small scale wastewater treatment plant. In this research, characteristics of flow ratio (flow / designed flow), effect on treatment efficiency of small scale wastewater treatment plant and assessment of optimal flow ratio were conducted through analysis on operation result of 18 small scale wastewater treatment plant in Bong-hwa gun. As a result, flow ratio shows the higher value during summer. However pollutants concentration in sewage was shown the higher concentration during autumn and winter. Treatment of small scale wastewater treatment plant is increased when flow ratio increased, and nutrient treatment efficiency is more sensitive to change of flow ratio than organic compound and suspended solids. According to this research result, it need to be maintained flow ratio 0.8 over value for stable treatment efficiency of small scale wastewater treatment plant.