• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.45-52
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• 2011

It is known that test methods to evaluate solder joint reliability are die shock test, die shear test, 3points bending test, and thermal shock test. The present study investigated the effects of failure mode on 3 types (as-reflowed, $85^{\circ}C$/85%RH treatment, and $150^{\circ}C$/10hr aging) of solder joints for flip-chip BGA package by using various test methods. The test methods and configurations are reported in detail, i.e. die shock, die shear, 3points bending, and thermal shock test. We focus on the failure mode of solder joints under various tests. The test results indicate that die shock and die shear test method can reveal brittle fracture in flip-chip ball grid array (FCBGA) packages with higher sensitivity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1186-1192
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• 2008

The reliability of gas turbine engine blades was studied. Yield strength, Young’s modulus, engine speed and gas temperature were considered as statistically independent random variables. The failure probability was calculated using five different methods. Advanced Mean Value Method was the most efficient without significant loss in accuracy. When random variables were assumed to have normal, lognormal and Weibull distributions with the same means and standard deviations, the CDF of limit state equation did not change significantly with the distribution functions of random variables. The normalized sensitivity of failure probability with respect to standard deviations of random variables was the largest with gas temperature. The effect of means and standard deviations of random variables was studied. The increase in the mean of gas temperature and the standard deviation of engine speed increased the failure probability the most significantly.

• The Korean Journal of Pain
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• v.30 no.3
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• pp.197-206
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• 2017

Background: Pain with neuropathic characteristics is generally more severe and associated with a lower quality of life compared to nociceptive pain (NcP). Short form of the Douleur Neuropathique en 4 Questions (S-DN4) is one of the most used and reliable screening questionnaires and is reported to have good diagnostic properties. This study was aimed to cross-culturally validate the Hindi version of the S-DN4 in patients with various chronic pain conditions. Methods: The S-DN4 is already translated into the Hindi language by Mapi Research Trust. This study assessed the psychometric properties of the Hindi version of the S-DN4 including internal consistency and test-retest reliability after 3 days' post-baseline assessment. Diagnostic performance was also assessed. Results: One hundred sixty patients with chronic pain, 80 each in the neuropathic pain (NeP) present and NeP absent groups, were recruited. Patients with NeP present reported significantly higher S-DN4 scores in comparison to patients in the NeP absent group (mean (SD), 4.7 (1.7) vs. 1.8 (1.6), P < 0.01). The S-DN4 was found to have an AUC of 0.88 with adequate internal consistency (Cronbach's ${\alpha}=0.80$) and a test-retest reliability (ICC = 0.92) with an optimal cut-off value of 3 (Youden's index = 0.66, sensitivity and specificity of 88.7% and 77.5%). The diagnostic concordance rate between clinician diagnosis and the S-DN4 questionnaire was 83.1% (kappa = 0.66). Conclusions: Overall, the Hindi version of the S-DN4 has good internal consistency and test-retest reliability along with good diagnostic accuracy.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.18 no.2
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• pp.96-101
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• 2007

Laryngopharyngeal reflux (LPR) is the retrograde movement of gastric contents into the larynx, pharynx, and upper aero-digestive tract. LPR differs from gastroesophageal reflux in that it is often not associated with heartburn and regurgitation symptoms. Otolaryngological manifestations of acid reflux include a wide range of pharyngeal and laryngeal symptoms. Belafsky et al. developed a useful self-administered tool, the reflux symptom index (RSI), for assessing the degree of LPR symptoms. Patients are asked to use a 0 to 5 point scale to grade the following symptoms: 1) hoarseness or voice problems; 2) throat clearing; 3) excess throat mucus or postnasal drip ; 4) difficulty swallowing; 5) coughing after eating or lying down; 6) breathing difficulties ; 7) troublesome or annoying cough; 8) sensation of something sticking or a lump in the throat; 9) heartburn, chest pain, indigestion or stomach acid coming up. A RSI score greater than 13 is considered abnormal. As there is no validated instrument to document the physical findings and severity of LPR, Belafsky et al. developed an eight-item clinical severity scale for judging laryngoscopic finding, the reflux finding score (RFS). They rated eight LPR-associated findings on a scale from 0 to 4 : subglottic edema, ventricular obliteration, erythema/hyperemia, vocal-fold edema, diffuse laryngeal edema, posterior commissure hypertrophy, granuloma/granulation tissue, and thick endolaryngeal mucus. A RFS score of greater than 7 was found to suggest LPR-associated laryngitis. Although both indices (RSI and RFS) are widely used, there is some controversy about their validity (sensitivity and specificity) and reliability (intra-rater and inter-rater) in LPR diagnosis and treatment. We discuss the validity and reliability of RSI and RFS with literature review.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.463-474
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• 2002

A two-dimensional water quality management model, Unsteady/Uncertainty Water Quality Model(UUWQM), is developed for a hydrodynamic analysis, an advection-diffusion analysis, and a reliability analysis by using uncertainty technique. The model is applied to the 35 km reach of Sungju to Hyunpoong in the midstream of Nakdong River. 2-D hydrodynamic and water quality analyses are peformed in this reach. Important input variables are decided by sensitivity analysis and verified by Monte Carlo method. Frequency distributions of water quality concentrations are computed from MFOSM method and Monte Carlo method at several locations in this study area. A water quality management system is constructed by calculating the violation probabilities of existing water quality standards.

• Korean Journal of Community Nutrition
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• v.17 no.2
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• pp.156-166
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• 2012

The aim of this study was to develop and evaluate the simple semi-quantitative food frequency questionnaire (FFQ) for assessing folate intake in women of reproductive age. We developed a 30-item FFQ, and tested the reliability and validity in 97 women aged between 20 and 39 yrs using the FFQs and 24-h recalls, which were carried out twice, respectively. Assessing the reliability, the correlation coefficients were 0.53 (Spearman's) and 0.49 (Pearson's) for folate. There was no significant difference of folate intake between FFQ1 and FFQ2. 36.1% subjects were classified into the same quartile and 83.5% into the same or adjacent quartile divided by folate intake. On determining the validity, the mean folate intake obtained from the FFQ (FFQ1) and 24h-recalls (2-d) were $306.6{\pm}167.2{\mu}g/d$ and $326.9{\pm}103.3{\mu}g/d$, respectively. There was no significant difference between folate intakes from the two methods. The correlation coefficients for folate were 0.24 (Spearman's) and 0.26 (Pearson's). 39.2% of the subjects were categorized into the same quartile and 70.1% were into the same or adjacent quartile. In addition, sensitivity (64.3%) and specificity (62.3%) were estimated to evaluate the adequacy of folate intake. These results suggest that this FFQ would be a useful and a valuable instrument to assess the intake of folate among the Korean women of child-bearing age.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.111-120
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• 2021

A tractor is an agricultural machine that performs farm work, such as cultivation, soil preparation, loading, bailing, and transporting, through attached working implements. Farm work must be carried out on time per the growing season of crops. As a result, the reliability of a tractor's transmission is vital. Ideally, the transmission's design should reflect the actual load during agricultural work; however, configuring such a measurement system is time- and cost-intensive. The design and analysis of a transmission are, therefore, mainly performed by empirical methods. In this study, a tractor with a measurement system was used to measure the actual working load in the field. Its hydro-mechanical transmission was then analyzed using the measured load. It was found that the velocity factor, load distribution factor, lubrication factor, roughness factor, relative notch sensitivity factor, and life factor affect the gear strength of the transmission. Also, loading conditions have a significant influence on the reliability of the transmission. It is believed that transmission reliability can be enhanced by analyzing the actual load on the transmission, as performed in this study.

• Nutrition Research and Practice
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• v.16 no.3
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• pp.366-378
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• 2022

BACKGROUND/OBJECTIVES: The purpose of this study was to develop a sodium index, which is a tool for estimating and assessing sodium intake easily and quickly, to assist in the prevention of various diseases induced by excess sodium intake in Korean adults. SUBJECTS/METHODS: The 24-h urine collection and dietary behavior surveys were performed on 640 healthy people in 4 regions of South Korea, and an equation for the estimation of 24-h sodium intake was developed. The validity and reliability of the equation were verified with 200 adults. The sodium index was developed by converting the estimated sodium intake using the equation. Finally, the sodium intake status of 1,600 adults was assessed using the sodium index. RESULTS: The equation included sex, age, body mass index, eating habit and dietary behaviors related to sodium intake. In validity test of the equation, the mean bias between sodium intake using 24-h urine analysis and using the equation from the Bland-Altman plots was -1.5 mg/day. The sensitivity and specificity of the equation for estimation of sodium intake were 80.5% and 64.4%, respectively. In the reliability test of the equation, there was no significant difference between the first and second sodium intakes calculated using the equations, and Spearman's correlation coefficient between the 2 sodium intakes was 0.98. Sodium intake can be assessed as 'very moderate' for 75-100 on the sodium index, 'moderate' for 100-150, 'careful' for less than 75 or 150-200, and 'severe' for 250 or more. When sodium intake was assessed using the sodium index in 1,600 subjects, 54.3% and 24.3% of the subjects were assessed to be in the 'careful' and 'severe' categories, respectively. CONCLUSIONS: Using a simple questionnaire, the sodium index can be used to monitor and assess sodium intake status, assisting in nutrition education and counseling in a large population.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.179-193
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• 1994

In the development of engineering designs, decisions are required irrespective of the state of completeness and quality of information, and are formulated under conditions of uncertainty. Furthermore, under conditions of uncertainty the design invokes risks. Thus, in the design of the structures, the currently used deterministic design method does not provide a realistic assessment of the actual safety or the reliability of the structures. It is desirable that decisions required in The process of the design invariably must be made based on the reliability analysis. Properties of soil material are subject to more uncertainty than those of other structural material. In the field of soil mechanics and foundation engineering, it needed to develop reliability-based design methods. In order to simplify the reliability analysis or the reliability-based design process of the structures associated with the active earth pressure, it is necessary to find the variation and the distribution type of the active earth pressure calculated from the basic properties of soils. Monte Carlo simulation is performed to obtain the relationship between the variation of the active earth pressure for cohessionless soils calculated by using Rankine formula and the basic soil properties and the distribution type of the earth pressure. A series of regression equations obtained by utilizing the multi-linear regression analysis is suggested in this paper and the sensitivity of the basic soil properties to the variation of The earth pressure is investigated. The type of distribution of the active earth pressure was found to be the beta distribution in most cases or to be very similar to the beta distribution, if the basic soil variables are normally distributed.

• Journal of Distribution Science
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• v.13 no.7
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• pp.73-83
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• 2015

Purpose - Recently, many large retailers have been frequently purchasing commercial brands. Not only the quality of products purchased but also the brand images are of concern in this process. Based on this rising trend, commercial brands have become an important issue in the retail business world, along with increasing general interest as well. Thus, this study focuses on the factors affecting commercial brand images and clarifies the impact of the resulting factors as well. First, store images and familiarity, price sensitiveness, and knowledge are presented as the effect factors for commercial brands. Second, the study tries to clarify the effect of commercial brand image on the reliability and loyalty of customers. Research design, data, and methodology - To conduct the study methodology, 250 questionnaires were distributed to retailers who have used large discount stores located in Busan to purchase a commercial brand a total of 234 valid questionnaires were used in the final analysis. To verify the hypotheses, a structure equation formula using Amos 20.0 was calculated. First, prior to the verification of hypotheses, the reliability and feasibility of the questions were tested, and as a result, the value of Cronbach's alpha was higher than 0.7, thereby showing reliability. Additionally, for the verification of the feasibility of the questions, a confirmation factor analysis was implemented. Results - First, variances such as store images, familiarity, price sensitivity, and knowledge were presented as the factors of effect on commercial brands. As a result of the hypotheses verification, all the effect factors presented in this study were confirmed as important variables of commercial brand images. The hypotheses were drawn based on the studies relating to existing commercial brands, and thereby, a result similar to previous studies was produced. However, the effect factors of the commercial brand image presented in this study shaped a new study model based on the previous studies. Second, it was found that commercial brand images had positive effects on the reliability and loyalty of customers. This study presented reliability and loyalty as the resulting factors of commercial brand image because they are the most important factors in relation to customer behavior and variables that can suggest marketing points for distribution businesses. Conclusions - This study focused on clarifying the factors that are important effect factors for commercial brand images. As a result, all the hypotheses were confirmed in this study, indicating a meaningful result, and thereby suggesting many points that can be presented to distribution businesses. First, the proper strategies should be developed based on the hypothesis that a store image, the familiarity of customers with brands, and the price sensitiveness and knowledge level of customers have an important effect on the choice of commercial brands. Additionally, the formation of such favorable images will have positive effects not only in terms of customer trust in the commercial brands but also in terms of their loyalty.