• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1479-1489
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• 2004

The effect of fluctuation of Equivalence Ratio (ER) in a turbulent reactive field has been studied in order to check the global combustion characteristics induced by the local fluctuation. When the flow is premixed on a large scale, closer examination on a small scale reveals that local fluctuations of ER exist in an imperfectly premixed mixture, and that these fluctuations must be considered to correctly estimate the mean reaction rate. The fluctuation effect is analyzed with DNS by considering the joint PDF of reactive scalar and ER, followed by modeling study where an extension of stochastic mixing models accounting for the ER fluctuation is reviewed and tested. It was found that models prediction capability as well as its potential is in favor to this case accounting the local ER fluctuation. However, the effect of local fluctuation did not show any notable changes on the mean global characteristics of combustion when statistical independence between the reactive scalar and ER field is imposed, though it greatly influenced the joint PDF distribution. The importance of taking into account the statistical dependency between ER and combustible at the initial phase is demonstrated by testing the modeled reaction rate.

• Nuclear Engineering and Technology
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• v.21 no.4
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• pp.321-331
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• 1989

A bench scale incineration process for the burnable radwaste has been constructed and operated at KAERI as a self-surpported development of incineration technology. The purposes of operating the process are to get experience in incineration, to analyze the characteristics of combustion and to test the performance of off-gas treatment units. Simulated paper and polyethylene wastes were incinerated. Volume reduction ratio and decontamination factor of the process have been determined to observe the economical efficiency and operational capability of the process. A methodology to estimate the acceptance limit of specific activity to an incineration facility by using a decontamination factor and to calculate the volume reduction ratio of the facility is introduced. The acceptance criteria for different radionuclides in the combustible waste at the bench scale incineration process are suggested using this methodology.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.1
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• pp.12-19
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• 2001

Study of turbulent mixing layers has been a popular subject from the point of view of both practical application and phenomenological importance in engineering field. Turbulent mixing layers can be applied in many fields where rapid transition to turbulence is desirable in order to prevent boundary layer separation or to enhance mixing. The ability to control mixing, structure and growth of the shear flow would obviously have a considerable impact on many engineering applications. In addition to practical applications, free shear flows are one of the simplest flows to understand the fundamental mechanism in the transition process to turbulence. After the discovery of large-scale vortical structure in free shear flows many researchers have investigated the physical mechanism of generation and dissipation processes of the vortical structure. This study investigated the role of the large-scale vortical structures in the turbulent mixing layer using LES(Large-Eddy Simulation). The result shows that the pairing interaction of the vortical structure plays an important role in the growth rate of a mixing layer. It is found that the turbulence quantities depend strongly on the velocity ratio. It is also found that the vorticity in the high-velocity-side can extract energy from the mean flow, while the vorticity in the low-velocity-side lose energy by the viscous dissipation. Finally the results suggest the guideline to obtain the desired flow by control of the velocity ratio.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.2
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• pp.13-24
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• 1996

The purpose of this study is to suggest optimum level of the Ratio of Greenery within the frame of vision in the interior landscape design through the analysis of visual character and preference of the interior landscape. The concept of the RG was defined as the ratio of projected area of plants higher than 1.2M against background wall from eye level. 5 photography of Interior landscape space -- 10,20,30,40 and 50% of the RG-- were constructed by computer graphic techinques. Likert scale and semantic differential scale were used to analyse visual character and preference of the interior landscape space. The analysis results are as follows : 1. Factors that compose of the image of the interior landscape have been found to be the "evaluation ", "complexity". The mean value of semantic differential scale showed a significant difference according to RG. When the RG was 20~30%, "Harmony" and "stability" was strongly recognized than the other factors and the interior landscape made the interior space natural and intimate. But at the RG 40!50%, users felt "stuffy" and "too complex" by many plants, so it was not efficient the Interior Landscape. 2. The visual preference was significantly different according to RG. The mean value of the visual preference was increased as the RG was higher, it was the highest at the RG 30%. But over the RG 30%, the preference level was declined. 3. Based on these results, this study suggests that the optimum level of RG in the Interior Landscape is 30%.at the optimum level of RG in the Interior Landscape is 30%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.244-254
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• 1996

Flow velocity was measured by, use of hot wire anemometer. Turbulence intensity was in proportion to mean flow velocity regardless of swirl velocity. And integral length scale has proportional relation with swirl velocity regardless of measurement position. Turbulent burning speed during flame propagation which was determined by flame photograph and gas pressure of combustion chamber was increased with the lapse of time from spark and was decreased a little at later combustion period. Because of combustion promotion effect, turbulent burning speed was increased according to increase of turbulence intensity. Burning speed ratio i.e. ratio of turbulent burning speed ($S_BT$) to laminar burning speed ($S_BL$) was found out by use of turbulence intensity u' and integral length scale $l_x$ , $\delta_L$ is width of preheat zone in laminar flame.

• Journal of Astronomy and Space Sciences
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• v.34 no.1
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• pp.45-54
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• 2017

This study examines the scale unique instruments used for astronomical observation during the Joseon dynasty. The Small Simplified Armillary Sphere (小簡儀, So-ganui) and the Sun-and-Stars Time-Determining Instrument (日星定時儀, Ilseong-jeongsi-ui) are minimized astronomical instruments, which can be characterized, respectively, as an observational instrument and a clock, and were influenced by the Simplified Armilla (簡儀, Jianyi) of the Yuan dynasty. These two instruments were equipped with several rings, and the rings of one were similar both in size and in scale to those of the other. Using the classic method of drawing the scale on the circumference of a ring, we analyze the scales of the Small Simplified Armillary Sphere and the Sun-and-Stars Time-Determining Instrument. Like the scale feature of the Simplified Armilla, we find that these two instruments selected the specific circumference which can be drawn by two kinds of scales. If Joseon's astronomical instruments is applied by the dual scale drawing on one circumference, we suggest that 3.14 was used as the ratio of the circumference of circle, not 3 like China, when the ring's size was calculated in that time. From the size of Hundred-interval disk of the extant Simplified Sundial in Korea, we make a conclusion that the three rings' diameter of the Sun-and-Stars Time-Determining Instrument described in the Sejiong Sillok (世宗實錄, Veritable Records of the King Sejong) refers to that of the middle circle of every ring, not the outer circle. As analyzing the degree of 28 lunar lodges (lunar mansions) in the equator written by Chiljeongsan-naepyeon (七政算內篇, the Inner Volume of Calculation of the Motions of the Seven Celestial Determinants), we also obtain the result that the scale of the Celestial-circumference-degree in the Small Simplified Armillary Sphere was made with a scale error about 0.1 du in root mean square (RMS).

• Journal of Oriental Neuropsychiatry
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• v.29 no.2
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• pp.69-77
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• 2018

Objectives: To determine the relationship between 2D:4D ratio and Minnesota Multiphasic Personality Inventory-2 Questionnaire (MMPI-2 scales). Methods: The 2D:4D ratio in 101 Korean medical students was measured. MMPI-2 test was performed. Results: In the unisex group, there were significantly positive correlations between the 2D:4D ratio and MMPI-2 scales of Hs, D, Pt, Sc, Si, RC1, RC2, RC8, INTR, ANX, OBS, HEA, BIZ, LSE, WRK, TRT, A, R, Mt, PK, and AAS while there were significantly negative correlations between the 2D:4D ratio and MMPI-2 scales of Es and Do. In the male group, there were significantly positive correlations between the 2D:4D ratio and MMPI-2 scales of Hs, RC1, RC8, HEA, and AAS while there were significantly negative correlations between the 2D:4D ratio and MMPI-2 scale of AGGR. In the female group, the 2D:4D ratio showed significantly positive correlations with MMPI-2 scales of Pt, Sc, Si, RC1, RC2, RC6, INTR, DEP, BIZ, LSE, WRK, A, Mt, PK, and Ho while it showed significantly negative correlations with MMPI-2 scale of Do. Conclusions: MMPI-2 scales are correlated with the 2D: 4D ratio. Therefore, 2D: 4D ratio could be used as an indicator to reflect multiphasic personality of individuals.

• Physical Therapy Korea
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• v.24 no.4
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• pp.20-28
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• 2017

Background: Rasch analysis has the advantage of placing both the items and the person along a single ratio scale and calibrates person ability and item difficulty onto an interval scale by logits. Therefore, Rasch analysis has been recommended as a better method for evaluating functional outcome questionnaires than traditional analyses. Objects: The aim of current study was to investigate item fit, item difficulty, rating scale, and separation index of the Korean version of the Fullerton Advanced Balance (KFAB) scale using Rasch analysis. Methods: In total, 93 patients with stroke (male=58, female=35) participated in this study. To investigate the item fit, difficulty, rating scale, and separation index of the KFAB scale, Rasch analysis was completed by the Winsteps software program. Results: In this study, all items of the KFAB scale were included in the Rasch model. The most difficult item was 'standing with feet together and eyes closed', and the easiest item was 'two-footed jump'. The rating scale was a 4-point scale instead of the original 5-point scale. Person and item separation indices showed high values that can identify a person with a wide range of balance ability. Conclusion: The KFAB scale appears to be a reliable and valid tool to assess balance function in patients with stroke. Furthermore, the scale was found to discriminate among stroke patients of varying balance abilities.

• Journal of The Korean Digital Architecture Interior Association
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• v.10 no.1
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• pp.65-74
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• 2010

This study has been given careful consideration to an induction of the mixed-use districts for the efficiency of Land Use, the rational plot planning and the mixture/complex among the functions in order to complement the zoning plan with the primary purpose to purify the usage of landscape. Furthermore, it is aimed to indicate the implementations through the medium of the in-depth analysis about the cardinal factors such as the standards on the regional location, building size and building uses in the case of designating the Mixed-use districts.Abstract This study has been examined by the aspect of scope for securing the adequacy of Site Division Restriction, Floor Area Ratio, Building Coverage Ratio and Outdoor Area Ratio in the "Mixed-Use Districts" and especially, by the medium of the in-depth analysis about the actual condition of building and outdoor space scales. It has been deduced the scale standards by using the simulation and correlation analysis among the factors of those buildings and outdoor spaces. Moreover, it has been applied the analysis method of using the building scale, especially, the latter has analyzed the total 1,656 different types classified by 3 patterns of Plottage and Building Coverage Ratio, 9 patterns of the factor change on Outdoor Area Ratio and 8 different patterns of road width.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.19-28
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• 2019

To minimize the impact of urbanization, accurate performance evaluation of Low Impact Development (LID) facilities is needed. In Korea, the method designed to evaluate large-scale non-point pollution reduction facilities is being applied to LID facilities. However, it has been pointed out that this method is not suitable for evaluating the performance of relatively small-scale installed LID facilities. In this study, a new design formula was proposed based on the ratio of LID facility area and contributing drainage area, for estimating the Stormwater Interception Ratio (SIR) for LID facilities. The SIR was estimated for bio-retentions, infiltration trenches and vegetative swales, which are typical LID facilities, under various conditions through long-term stormwater simulation using the LID module of EPA SWMM. Based on the results of these numerical experiments, the new SIR formula for each LID facility was derived. The sensitivity of the proposed SIR formula to local rainfall properties and design variables is analysed. In addition, the SIR formula was compared with the existing design formula, the Rainfall Interception Ratio (RIR).