• Journal of the Korean Society of Industry Convergence
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• v.21 no.3
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• pp.141-147
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• 2018

In a time when product development cycles are getting shorter and shorter, many companies are making efforts to develop products with high reliability in a short period of time, accelerated life test is widely used as a method to quickly evaluate reliability. Accelerated life test reduces the test life or the life of the product from the observed data by shortening the lifetime of the product or abruptly lowering the performance under the worse condition than the actual condition in order to shorten the test cost or the test time. In this paper, BL3640A-06P+RB35, DC12V model, which is used in the support device of an automatic rotation type digital signage, which display various information such as textures and images on a display screen in a public place or a commercial space, BLDC motors were subjected to a constant stress test and at the rotational speed of 1rpm, $180^{\circ}$ rotation and reverse rotation under actual use conditions, the stress was imposed on the rotating speed of 2rpm and the weight of the actual installed product from 22.2kgf to 10kgf were installed. The lifetime of the actual use environment condition is 23,545 hours and the rotation speed is accelerated. The life time of the acceleration condition with the additional weight is 1,380 hours. The acceleration factor is calculated as 17.06, the one year guarantee test day is 235 days to 14 days, of the period from 470 days to 28 days, and the third year from 704 days to 42 days. The test date of the BLDC motor was tested on the shortened test date, and the rotational speed and the current value were measured. It is found that there is no defect even if it operates as the test date corresponding to the specified one year warranty period and the 3 year accelerated life test which is experimented. Using the statistical technique of the regression analysis the expected time for the motor to defect to #4 samples was 20 years.

• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.63-71
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• 2012

This study aimed to evaluate the accuracy of breast cancer diagnosis of digital mammography which is in the highest interest of breast imaging test, and to investigate the characteristics of breast cancer patients. For this purpose, 57 breast cancer patients who underwent breast imaging test were examined between May 2010 and June 2011. The average age of the breast cancer patients was 50.8 years old, and the most frequently occurring location was the upper outer quadrant (UOQ), accounting for 33.3%. By age, the highest occurrence rate of breast cancer was the age group of 40~49, accounting for 42.1%. As for the breast composition of the breast cancer patients, fatty breast accounted for 31.6% (18/57) and dense breast for 68.4% (39/57), indicating that nearly 70% of the breast cancer patients have dense breast. It was found that the detection rate of breast cancer was the highest (45.3%) when both microcalcification and mass are simultaneously present in the radiographic lesion of the breast imaging. In dense breast, the mass without microcalcification was lower in detection rate than fatty breast. Accordingly, the mass is the cause of raising the false negative rate in dense breast. The findings show that the false negative rate of digital mammography was 7.0% and the sensitivity 93.0%. Also, the false negative rate of dense breast was 12.8%, and the sensitivity 87.2%, indicating that the sensitivity to breast cancer in this study was higher than the dense breast of previously reported screen film mammography.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.22 no.4
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• pp.271-286
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• 2011

Objectives : The purposes of this study were to develop a mental health screening questionnaire and the practical intervention programs or guidelines which can be used in middle and high schools by students and teachers. Methods : The Adolescent Mental health & Problem behavior Screening Questionnaire II (AMPQ-II) was developed and was tested for reliability and validity using nationwide data from 2,180 middle and high school students and 2,145 teachers. Results : The AMPQ-II was measured by both students and teachers. The correlation coefficient of the test-retest test was 0.567 and internal consistency was high (Cronbach's alpha=0.878). Five factors such as worry and thought, mood and suicide, academic and Internet-related problems, peer problems, and rule violations were proposed. We also developed a practical guideline and manuals which can be easily used by secondary school teachers to screen for and manage mental health problems at school. Conclusion : The AMPQ-II can be a useful and reliable tool to screen for mental health problems in middle and high schools in South Korea.

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.79-94
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• 2020

The purpose of this study is to analyze the difference in the effect of presence for the activation of virtual reality sports on participation satisfaction, to suggest continuous screen golf exercise participation, and to provide empirical and academic data for the development of the entire virtual reality sports market. To achieve this purpose, the survey period was from March 13 to May 13, 2020, with five researchers and assistants. The purpose of this study and the questionnaire were fully explained to consumers who experienced screen golf directly, and 247 questionnaires were used as the final valid sample by making a questionnaire with self-administration method. The data processing method was the statistical program Windows SPSS 18.0. First, factor analysis and reliability analysis, second, frequency analysis mean(M) and standard deviation(SD), third, Scheffe analysis among t-test and One-way ANOVA analysis, fourth, correlation analysis between variables and multiple regression analysis were conducted. The results of this study through these methods and procedures are as follows. First, there was a significant difference in participation satisfaction of presence in gender, and participation period of general characteristics. Second, there was a high difference in social presence, social self-reliance, and Ego, which are sub-factors of Presence, in social satisfaction, psychological satisfaction, and physical satisfaction. Third, the sub-factors of Presence, Social Presence, Social Self-Reliance, and Ego, were found to have a high effect on the sub-factors of Participation Satisfaction, Social Satisfaction, and Psychological Satisfaction.

• Journal of Broadcast Engineering
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• v.20 no.6
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• pp.901-911
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• 2015

Many studies tried to develop a 3D display based stereo test as a substitute for the conventional stereo test. Although many 3D monitor based stereo tests have various advantages over the conventional stereo tests with printed stimuli, they have a crucial limitation in manipulating disparity. The least value for disparity manipulation is one pixel, which is too big to screen the normal stereo acuity in pc environment with a short viewing distance. In this explorative study, a Gabor image was employed as a test stimulus, because its position can be manipulated by changing its phase information, which allows sub-pixel manipulation for disparity. Instead of employing the methods of the conventional stereo tests where measurement was made only once for each of a wide range of disparity values, 10 replications were administrated for each of 6 disparity levels. The results from the test using Gabor images were compared with those using random dot stimulus because the latter stimulus was exactly the same as that of the conventional stereo test. The correlation coefficient between two tests was found to be moderate. After one month later, the whole test was repeated in the same settings. The correlation coefficient between test and retest results from Gabor images was found to be as high as that from a random dot stimulus, implying high test-retest reliability. These results suggest that a Gabor stimulus could be used as a test stimulus for the valid and reliable stereo test, even in the limited condition, such as 3D environment with a short viewing distance and a condition for evaluating the stereo acuity very precisely.

• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.2
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• pp.135-146
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• 2020

In the strawberry cultivation areas and domestic farms, two-spotted spider mites are the most serious pests. It decreases the product yield due to the direct feeding of chlorophyll by the mites resulting in reduced photosynthetic ability of host plant. In this study, a simplified acaricidal effect evaluation system (SAEES) was employed to choose the effective acaricidal products among 10 items based on leaf-dipping bioassay methods. SAEES had the advantage of being able to screen four commercial products with three replications at the same time in the recommended concentration. The susceptible strains (SL_YS) showed a high mortality rate of about 90-100%, whereas the mortality of local strains was differed by each acaricides. It suggests that the acaricide responses of field populations might differ due to spray frequencies and acaricide product. An efficacy index (0.8-1.0) was determined based on the mortality of susceptible strain, which would allow the most effective commercial products to be selected by the range of this index. In summary, SAEES will enable the selection of effective commercial products and contribute to increasing control against T. urticae in strawberries.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.888-896
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• 2011

A white smoke hand grenade, KM8 is used to make smoke screen in order to provide visual field interceptions or signals. The grenade fails when its time to emit smoke is longer than the specified emission time so that the smoke concentration becomes lighter. This paper considered failure in smoke emission time, and evaluated its storage lifetime. The main objective of this paper is to modify the present specification limits of smoke emission time for the efficient process control in manufacturing, through analyzing effect of its specification change on the storage lifetime, based on the lifetime evaluation results. Accelerated degradation test was performed and then failure in smoke emission time was reproduced from the test. And estimated storage lifetimes from the accelerated test results was compared to evaluated lifetimes of grenades using the ASRP data. Past process testing results of the grenade in manufacturing were analyzed in this paper. Then, each storage lifetime for the specifications, ${\pm}3$ and ${\pm}5$ in seconds, extended from the current specification in manufacturing were estimated using the past testing results, and compared to one another.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.9
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• pp.714-719
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• 2013

A turboprop aircraft for this study is required to operate at icing condition in order that it performs its given mission. So an air intake system of the turboprop aircraft should be designed and verified not only to provide the maximum possible total pressure at engine inlet at normal flight condition, but also to include an inertial separator which protects Foreign Object Debris (FOD) like ice or snow at icing condition from entering into the engine inlet screen which can cause or lead an catastrophic engine failure like engine flame-out or severe damage. So an air intake assembly incorporating a variable geometry inertial separator has been designed and then CFD/structural analysis for the assembly was performed to see its design results. Then 35% scaled model of the air intake assembly was manufactured and wind tunnel test was done. This paper describes the detailed design results for the aerodynamic design, analysis and wind tunnel testing during the development process of the air intake assembly.

• Archives of design research
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• v.18 no.2 s.60
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• pp.255-264
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• 2005

The development of personal computers and the Internet led to changes of instructor-student and student-student relationships in design education. New resources of design education with proper materials and tools have to be offered for teaching and learning. The purpose of this research is to develop Basic Graphic Tools(BGTs) on screen that help students to practice the design principles, and to evaluate the BGTs' usability to enhance the credibility of extra tools for online design learning. The BGTs has to be developed to minimize the gap between the online and traditional classroom settings and to maximize the diverse advantage of lecture content driven from technology. Students were given certain design requirements to explore BGTs and a learning guide/performance test after the lecture to evaluate the tools. The test was performed under the e-learning program serviced by C college. This research has presented some encouraging results and raises questions toward future work: how do BGTs impact the feasibility of an online design lecture.

• Women's Health Nursing
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• v.19 no.1
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• pp.13-22
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• 2013

Purpose: This study was conducted to evaluate Korean version of the beliefs about Papanicolau (Pap) test and cervical cancer [CPC-28] in unmarried university students. Methods: The Korean version of CPC-28 (K-CPC-28) was developed through forward-backward translation techniques. A reliability, confirmatory factor analysis and correlations coefficients were evaluated. Data were collected from 303 unmarried female students attending university using a questionnaire that included28 items of CPC, 5 items of susceptibility of cervicalcancer and 8 items of HPV knowledge. Results: K-CPC-28 had reliable internal consistency with Cronbach's ${\alpha}$=.74 of six subscales ranged from .66 to .80. Factor loadings of the 28 items of subscales ranged from .31 to .86. Six factors in this study explained 55% of the total variance. In convergent validity of the K-CPC-28, the subscales of K-CPC-28 were significantly correlated with susceptibility scale of cervical cancer and HPV knowledge scale. Conclusion: K-CPC-28has satisfactory construct validity and reliability. It seems to be an acceptable tool to assess the attitudes toward cervical cancer prevention and Pap smear in unmarried women. This tool would be also applicable to screen the risk group in cervical cancer prevention and to identify its association with actual Pap test or cervical cancer prevention behaviors.