• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.463-470
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• 2014

Stealth technology of combat aircraft is most significant capability in recent air battlefield. As the detector of IR missiles is being developed, IR stealth capability which is evaluated by IR signature level become more important than it was in previous generation. Among IR signature of aircraft from various sources, aerodynamic heating dominates in long-wavelength IR spectrum of $8{\sim}12{\mu}m$. Skin temperature change by aerodynamic heating which is derived by effects of Mach number and structure. The 4th and 5th generation aircraft are selected for calculation of the skin temperature, and its height and velocity in numerical conditions are 10,000 m and Ma 0.9~1.9 respectively. Aircraft skin temperature is calculated by computing convection of fluid and conduction, convection and radiation of surface. As the aircraft accelerates to higher Mach number, maximum skin temperature increases more rapidly than average temperature and temperature distribution changes in more sharp, interactive ways. The 4th generation aircraft whose shape is more complex than that of the 5th generation aircraft have complicated temperature distribution. On the other hand, the 5th generation aircraft whose shape is relatively simple shows plain temperature distribution and lower skin temperature in terms of both average and maximum value.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.16 no.1
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• pp.9-18
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• 2012

Objectives The aim of this study is to propose an optimized tongue colour interpolation method to achieve accurate tongue image rendering. Methods We selected 60 colour chips in the chips of DIC color guide selector, and then divided randomly the colour chips into two groups. The colour chips of a group (Gr I) were used for finding the optimized colour correction factor of error and those of the other group (Gr II) were used for verifying the correction factor. We measured colour value of the Gr I colour chips with spectrophotometer, and took the colour chips image with a digital tongue image system (DTIS). We adjusted colour correction factor of error to equal the chip colour from each method. Through that process, we obtained the optimized colour correction factor. To verify the correction factor, we measured colour value of the Gr II colour chips with a spectrophotometer, and took the colour chips image with the DTIS in the two types of colour interpolation mode (auto white balance mode and optimized colour correction factor mode). And then we calculated the CIE-$L^*ab$ colour difference (${\Delta}E$) between colour values measured with the spectrophotometer and those from images taken with the DTIS. Results In auto white balance mode, The mean ${\Delta}E$ between colour values measured with the spectrophotometer and those from images taken with the DTIS was 13.95. On the other hand, in optimized colour correction factor mode, The mean ${\Delta}E$ was 9.55. The correction rate was over 30%. Conclusions In case of interpolating colour of images taken with the DTIS, we suggest that procedure to search the optimized colour correction factor of error should be done first.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1102-1108
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• 2014

This study was to compare the protection abilities of an SPF through ground or underwater casting. A mat of 1/10 scale was made and then mortar was placed on the ground and submerged conditions. A limit velocity of each mat was estimated with this experiment. As a result of the test, the mat failed because of the decrease of bearing power in the center of the waterway. On the one hand, the edge of the mat, where the velocity is slow, secures stability. The result of the limit velocity analysis suggests that a velocity of ground placement with 6.51m/s and underwater casting with 9.80m/s is the minimum to ensure stability. When SPF mat with a thickness of 0.50m is replaced with a concrete block, it is calculated to need a maximum thickness of 2.21m.

• Safety and Health at Work
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• v.9 no.3
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• pp.296-307
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• 2018

Background: Safety culture, acting as the oil necessary in an efficient safety management system, has its own weaknesses in the current conceptualization and utilization in practice. As a new approach, resilience safety culture (RSC) has been proposed to reduce these weaknesses and improve safety culture; however, it requires a valid and reliable instrument to be measured. This study aimed at evaluating the reliability and validity of such an instrument in measuring the RSC in sociotechnical systems. Methods: The researchers designed an instrument based on resilience engineering principles and safety culture as the first instrument to measure the RSC. The RSC instrument was distributed among 354 staff members from 12 units of an anonymous petrochemical plant through hand delivery. Content validity, confirmatory, and exploratory factor analysis were used to examine the construct validity, and Cronbach alpha and test-retest were employed to examine the reliability of the instrument. Results: The results of the content validity index and content validity ratio were calculated as 0.97 and 0.83, respectively. The explanatory factor analysis showed 14 factors with 68.29% total variance and 0.88 Kaiser-Meyer-Olkin index. The results were also confirmed with confirmatory factor analysis (relative Chi-square = 2453.49, Root Mean Square Error of Approximation = 0.04). The reliability of the RSC instrument, as measured by internal consistency, was found to be satisfactory (Cronbach ${\alpha}=0.94$). The results of test-retest reliability was r = 0.85, p < 0.001. Conclusion: The results of the study suggest that the measure shows acceptable validity and reliability.

• Journal of Korea Water Resources Association
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• v.50 no.8
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• pp.579-586
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• 2017

In order to analyze the quantitative water withdrawal amount of intake pipe with functional screen and to evaluate the improvement effect of the suspended solid and turbidity through the filter media, four-step research methods were suggested. In the first step, laboratory scale experiments were constructed to determine the constitution method of the sample device filter media. In the second step, sample device was constructed and the flow rate was observed through intake pipe with functional screen. In the third step, flow rate was observed at different turbidity conditions for each filter material, and the hydraulic conductivity was estimated using MODFLOW. Finally, numerical model was constructed with the MODFLOW for the sample device and the estimated hydraulic conductivities were applied to the third step and the amount of water withdrawal was analyzed. As a result of applying hydraulic conductivity at 0 NTU, 39.96% more withdrawal was calculated than the observed flow rate. On the other hand, when hydraulic conductivity was applied at 100~120 NTU, the difference in flow rates was 9.41%.

• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.230-235
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• 2005

The main purpose of the flocculation process is to make flocs bigger to be removed easily in the following processes. The flow pattern and mixing intensity have a great influence on flocculation. In this study, the flow pattern was examined by a hydraulic tracer-test, where 3 water treatment plants having $800,000m^3/d$, $44,000m^3/d$ and $40,000m^3/d$ were employed. Also, the settling test was conducted to find out the relationship between the mixing intensity and the settling ability of flocs. The hydraulic tracer-test was conducted for the various flocculation processes that have different structures of flocculation basins. In the result, the retention time distribution (RTD) curves for the flocculation processes were quite different. In case of the inappropriate structure of the flocculation basin, the flow is not even so that the floc does not grow enough. To find out the relationship between mixing intensity and settleability of flocs, G-values were calculated and the settling test was conducted for two flocculation basins which have the same conditions except the G-value. For the flocculation basin with uneven G-value, the floc settleability was revealed poor. On the other hand, the flocculation basin with even G-value, the settleability was better than the previous one. From these experimental results, it is confirmed that the flow pattern is closely related to the structure of the flocculation basin and the settleability is affected by mixing intensity. Therefore the flow pattern and the strength of the mixing intensity should be examined sufficiently to design and operate flocculation basin.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.959-967
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• 1988

In this paper, 2-DOF vehicle suspension system with a semiactive on-off damper was studied for improving the ride comfort. It is known that a nonlinear hydraulic damper, which generates force proportional to the square of the relative velocity, can describe the actual fluid resisting type damper more properly than the traditional viscous damping model. On the other hand, hydraulic damper adoption in analysis makes the system nonlinear and causes difficulties to get the system response. In this work, time domain direct integration method was used to calculate system displacement and acceleration. first of all, the response of the suspension system experiencing a given road profile was optimized by Lagrangian multiplier method within the range of given damping coefficients. The appropriate on-loaf damping values were obtained by averaging the already calculated optimum damping coefficients from Lagrangian techniques. The criterion to control the on-off mechanism was determined by examining the suspension efficiency. It was found that the best out of practically applicable criteria is following the sign (positive and negative) of the multiplication of relative displacement and velocity. Judging from the theoretical calculations, it was proved that the semiactive on-off damper can increase suspension efficiency as much as 8-11% in object function.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.3 s.120
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• pp.241-248
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• 2007

A study has been conducted to investigate the subjective responses of loudness and annoyance according to the exposed time of urban traffic noise in controlled laboratory environment. To make a closer inspection into psychological response relevant to noise characteristics while varying the time of exposure to noise, the subjects were presented a set of noises with different exposed time and requested to judge spontaneously on a 100-unipolar scale. To be concrete, the subjects were exposed to noises being varied in time from 15 sec up to max. 1,200 sec for the controlled traffic noise sources. So far achieved from laborious tests, it has an importance being on the logarithmic relations of perceived loudness and exposed time, say, it is more increased the perceived loudness in the sorter exposed time than in the longer exposed time. However, the trend is said to be not effective for the case of annoyance. On the other hand, the subjective impressions on relative annoyance of noise is shown to be correlated with the noise characteristics such as loudness (sones), tonality and time with logarithmic scale, the product correlation moment being calculated as $R^{2}=0.99$. The variances to be explained for annoyance assessments through varying the time of exposure were ranged between 30 % and 50% for the exposed time, $27{\sim}37%$ for tonality, and $34{\sim}20%$ for loudness, respectively With these results, hopefully, it can be helpful for those who want to work out an experimental design for evaluating an environmental noise or to quantify any psychological dimensions found in annoyance assessments.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.277-286
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• 2015

This study calculated the NDVI and the NDBI of the land-use change in major cities at North Korea through Landsat imagery, and analyzed the spatiality(LISA) with difference discretization of the UI index. As a result of the research, we could identify that the degree of urbanization has been increased in both Gaesung and Pyeongyang, but showed opposite spatial tendency to each other. The urban index of Pyeongyang, a nucleus district of North Korea, has been progressed quicker than Gaesung since 1994, while the urbanization development was being progressed also in general, as it expanded from the existing downtown area. On the other hand, the urbanization took place intensively at one region in Gaesung by developing the vegetation area that forest transfers into a built-up area, which has been judged from the great dynamic range of NDVI values. In conclusion, it is possible to extract necessary data for understanding the degree of urbanization and spatial characteristics of North Korea through the UI and the LISA analysis that are considered to propose useful methodology in investigating changes in North Korean cities and political levearage.

• Journal of Fashion Business
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• v.17 no.1
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• pp.131-144
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• 2013

The purpose of this study was to analyse the structure and contents of clothing construction field in the middle-school textbook of technology and home economics with curriculum revised in 2007. 10 kinds of textbooks certified by Ministry of Education, Science and Technology in 2010 were selected and home economics field in them was the subject of this study with the external characteristics such as textbook system, instruction area and contents included. This study was content analysis-oriented and descriptive with data calculated by frequency and percentage. The findings are as follows. In 'Reality of Home-Life', food life area showed highest as 34.4% followed by clothing life(28.7%) and dwelling life(28.7%). The portion of present teachers in writing staffs was highest while there was no textbook where professors of each field were included in writing staffs. The contents of costume society, clothes material, clothes management from section 'Choice and Management of Clothes' in the chapter 'Family Life' and clothing construction from the section 'Making and Modifying Clothes' of the chapter 'Reality of Home-Life' were analysed in this study. Clothing construction-related fields were suggested separately by method of measurement, construction theory, drafting theory, drafting an original form, fabric trimming, utilization of the original form, length measure, cloth cutting, hand stitching, how to use a sewing machine, basting and correction, needlework process, completion, and evaluation. The contents of the unit 'Making Shorts' were about clothing construction theory, human body measurement, drafting an original form, process of making shorts and activity/research/experience. The contents of the unit 'Wearing Clothes after Fixing' in clothing construction-related field were about how to fix and recycling.