• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.39-42
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• 2003

Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modern air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras$(1280pixel\times1024pixel)$ were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.6 s.237
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• pp.737-746
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• 2005

The present study investigates heat/mass transfer and flow characteristics in a ribbed rotating passage with turning region. The duct has an aspect ratio (W/H) of 0.5 and a hydraulic diameter ($D_h$) of 26.67 mm. Rib turbulators are attached in the cross arrangement on the leading and trailing surfaces of the passage. The ribs have a rectangular cross section of $2\;mm\;(e){\times}\;mm\;(w)$ and an attack angle of $70^{\circ}$. The pitch-to-rib height ratio (p/e) is 7.5, and the rib height-to-hydraulic diameter ratio ($e/D_h$) is 0.075. The rotation number ranges from 0.0 to 0.20 while the Reynolds number is constant at 10,000. To verify the heat/mass transfer augmentation, internal flow structures are calculated for the same conditions using a commercial code FLUENT 6.1. The heat transfer data of the smooth duct for various Ro numbers agree well with not only the McAdams correlation but also the previous studies. The cross-rib turbulators significantly enhance heat/mass transfer in the passage by disturbing the main flow near the surfaces and generating one asymmetric cell of secondary flow skewing along the ribs. Because the secondary flow is induced in the first-pass and turning region, heat/mass transfer discrepancy is observed in the second-pass even for the stationary case. When the passage rotates, heat/mass transfer and flow phenomena change. Especially, the effect of rotation is more dominant than the effect of the ribs at the higher rotation number in the upstream of the second-pass.

• Korean Journal of Adult Nursing
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• v.19 no.2
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• pp.167-177
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• 2007

Purpose: This cross-sectional survey research was undertaken to identify the factors influencing time from onset to hospital arrival of stroke patients and to provide basic information for the development of intervention programs for stroke patients. Methods: The data were collected using a convenient sampling method from three hospitals in Inchon. The subjects were 78 patients who were diagnosed as stroke by doctor and they voluntarily participated in the study. Results: On the average, subjects arrived at the hospitals by 16.72 hours after the onset of stroke events with the range from 0.17 hours to 72 hours. Thirty-four(43.6%) subjects arrived within 3 hours which can maximize treatment effects. There was significant difference in hospital presentation time according to the level of knowledge(${\chi}^2=18.629$, p=.0003). A negative correlation was found between the hospital presentation time and self-efficacy (r= -.320, p=.004). Stepwise multiple regression analysis revealed that the most powerful predictor was self-efficacy. Self-efficacy, the level of knowledge and physical symptoms were significant factors and accounted for 21.7% of the variance of hospital presentation time in stroke patients. Conclusion: According to the results, self-efficacy is a useful concept for reducing the hospital presentation time from onset of attack in stroke patients. Therefore, nurses should consider educational programs which include not only a knowledge of stroke and recurrence prevention but also the concept of self-efficacy.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.27 no.2
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• pp.109-118
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• 2016

Objectives: The aim of this study was to develop the computerized Comprehensive Learning Test-Reading (CLT-R) to evaluate the cognitive processes and achievements related to their basic reading ability and identify dyslexia in children and adolescents in South Korea. We also obtained the normative data and evaluated the reliability and validity of the test. Methods: We developed the CLT-R, including the word attack/nonword decoding, paragraph reading, sound blending, nonword repetition, rapid automatized naming, letter-sound matching, visual attention, orthography awareness, and digit span tests, for the purpose of diagnosing dyslexia. We investigated the reliability and validity of the tests and gathered the normative data from 399 subjects (male 48.9%), aged 5-14 years, from the last grade in kindergarten to middle school, dwelling in Seoul and Gyeonggi Province, South Korea. Results: No statistical differences were observed between the means of the tests and retests of the CAT. The mean of the correlation coefficient of the test-retest scores was 0.85. According to the construct validity test calculated by principal constant analysis using the oblique rotation method, 4 factors explained 70.0% of the cumulative variances. In addition, the normative data were obtained for all of the CLT-R subtests. Conclusion: The computerized CLT-R can be used as a reliable and valid tool to evaluate the reading achievement and reading related cognitive process in Korean children and adolescents in schools, clinics, and research institutes.

• Korean Journal of Occupational Health Nursing
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• v.23 no.1
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• pp.28-38
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• 2014

Purpose: This research is a correlative study to assess the relationships of musculoskeletal subjective symptoms disorders and health promotion behavior of the daily plant construction workers. Methods: The subjects were comprised of 306 daily plant construction workers by self-reported questionnaires on October 19, 2011. The instruments used for this study were musculoskeletal subjective symptoms disorders (NIOSH) and health promotion lifestyle profile II (HPLP-II). The data were analyzed using SPSS/WIN 14.0. Results: The scores of health promotion behavior of daily plant construction workers were 2.13, and the scores of health promotion behavior were significantly different depending on gender (t=-2.51, p=.013), religion (t=3.10, p=.002), owning house (t=2.59, p= .010), exercise (t=6.01, p<.001), time to rest during work (t=2.21, p=.027), and work satisfaction (F=8.97, p<.001). The musculoskeletal subjective symptoms disorders attack rate was 90.5%. The results of the correlative study to assess relationships showed significant negative correlation between musculoskeletal subjective symptoms disorders and health promotion behavior (r=-1.45, p=.011). Conclusion: The results of the study showed that it was lower level of health promotion behavior level. Therefore, to increase the health promotion behavior of the daily plant construction workers, a great deal of efforts are required at the level of the government, employers and workers.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1672-1677
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• 2004

Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modem air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras($1280pixel{\times}1024pixel$) were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

• Journal of Navigation and Port Research
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• v.34 no.5
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• pp.325-330
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• 2010

An open water rudder test was carried out to figure out the flow characteristics around a twin rudder at $Re=1.5{\times}10^4$. In the analysis, the unique characteristics of a twin rudder, which affects rudder forces, were explained. The analysis includes varying angles of attack from 10 to 30 degrees. In this paper, the measured results have been compared with each other to predict the performance characteristics of a twin rudder's 2-dimensional section by 2-frame grey level cross correlation PIV method. The length L=0.75C between upper and lower rudders could be defined as the critical length.

• Journal of Yeungnam Medical Science
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• v.7 no.1
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• pp.61-68
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• 1990

To assess the role of multiple factors in influencing occurrence of ventricular premature complexes after acute myocardial infarction twenty-four hour Holter electrocardiographic tape recording were made in 40 survivors of an acute myocardial infarction 10 to 20 days after attack. Ventricular premature complexes were found in 72.5percent of the patients. The incidence and grade of ventricular premature complexes in the early postinfarction period were not correlated with left ventricular function, age, sex, smoking, dibetes mellitus, previous angina, and previous myocardial infarction. The occurrence of ventricular premature complexes showed a positive correlation with the occurrence of ST-T change. The occurrence of ventricular premature complexes during sleep hours was compared to the awake state. In 22 patients. the incidence of ventricular premature complexes was reduced during sleep. If patients free of ectopic activity during 24-hour monitoring sessions are excluded from analysis, the 22 of patients, or in 76percent, sleep was associated with a lowered occurrence of ventricular extrasystoles.

• Convergence Security Journal
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• v.18 no.3
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• pp.77-85
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• 2018

With the convergence of communications network between control system and public network, such threats like information leakage/falsification could be fully shown in control system through diverse routes. Due to the recent diversification of security issues and violation cases of new attack techniques, the security system based on the information database that simply blocks and identifies, is not good enough to cope with the new types of threat. The current control system operates its security system focusing on the outside threats to the inside, and it is insufficient to detect the security threats by insiders with　the authority of security access. Thus, this study conducted the importance analysis based on the main event log list of "Spotting the Adversary with Windows Event Log Monitoring" announced by NSA. In the results, the matter of importance of event log for the detection of insider threats to control system was understood, and the results of this study could be contributing to researches in this area.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.27-37
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• 2011

dth-order power analysis can safely be defended by dth-order masking method. However, as the degree of applied masking method increases, it can significantly decrease effectiveness of cryptosystem. The existing statistical analysis on high-order power analysis contains only analysis on second power analysis. However, this means absent of safety standards when crypto engineers apply 3rd or more order masking. this absent of standards can lead to insignificant usage of masking method which can significantly decrease effectiveness of cryptosystem. In this dissertation, we have generalize statistical values on high-order power analysis to establish these standards. In other words, we have generalized the value of a correlation coefficient when calculation of high-order power analysis methods are performed. That is to say, it can greatly be used to indicate a degrees that can be applied on further usage of masking method.