• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2228-2233
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• 2008

This research paper aims to establish a test process of the AFE SiP chip. It measured the sensitivity, current consumption and power consumption both on the evaluation socket board and Catalyst load board. As a result, the sensitivity became deteriorated with an average of 0.2[dBm] at the channel 62 only, the current consumption increased to an average of 0.57[mA] and the power consumption increased to an average of 1.76[mW], But all characteristics incomes the tolerance of the measurement, it also keeps almost the same level. Therefore this design of the test process improved a valid design.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.339-347
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• 2005

A type IP-2 transport package should prevent a loss or dispersal of the radioactive contents and a more than $20\%$ increase in the maximum radiation level at any external surface of the package when it were subjected to the drop test under the normal conditions of transport. If a shielding thickness of IP-2 transport package is thick, a bolted lid type may prevent a loss or dispersal of the radioactive contents than the door type of ISO containers which are generally used as a type IP-2 transport package. In this paper, to evaluate the effect of drop directions on the bolt tension and the coherence of a bolt, the drop tests of preliminary small model are tested and evaluated for seven directions before the drop test of a type IP-2 transport package with a bolted lid type under the normal conditions of transport. Seven drop directions which are a bottom-vertical drop, a lid-vortical drop. a horizontal drop and four corner drops have been carried out. Using a force sensor, the bolt tension during the drop impact is measured. The coherence of bolt is evaluated by the difference between the fastening torque of bolt before a drop test and the unfastening torque of bolt after a drop impact.

• The Journal of Korean Medicine
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• v.24 no.3
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• pp.118-129
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• 2003

Objective : To learn the distributional characteristics of Sasang constitutions, Methods : We statistically analyzed those 1338 patients who had been treated at Iksan Wonkwang Oriental Medicine during the period of three years from 2000 to 2002. The data were obtained through the electronic chart developed by Kim Jong- Yeol, and analyzed using the statistical Package SPSS. Results : The distributional ratio of Soeumin : Soyangin : Taeumin was 22.8 : 29.2 : 47.8. Thus the hypothesis : 'the distributional ratio of Soeumin : Soyangin : Taeumin is 2 : 3 : 5' was barely rejected by $x^2$ test for goodness-of-fit at the significance level of 5 %. When $x^2$ test for homogeneity was applied, the distributional characteristics between women and men were different and the distributional characteristics among several age groups were different under significance level of 5%. Conclusion : Though the hypothesis: 'the distributional ratio of Soeumin : Soyangin : Taeumin is 2 : 3 : 5' was rejected by $x^2$ test at the significance level of 5%, the observed distributional ratio was not so far away from the hypothesis.

• Communications for Statistical Applications and Methods
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• v.22 no.6
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• pp.665-674
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• 2015

Lack of a general matrix formula hampers implementation of the semi-partial correlation, also known as part correlation, to the higher-order coefficient. This is because the higher-order semi-partial correlation calculation using a recursive formula requires an enormous number of recursive calculations to obtain the correlation coefficients. To resolve this difficulty, we derive a general matrix formula of the semi-partial correlation for fast computation. The semi-partial correlations are then implemented on an R package ppcor along with the partial correlation. Owing to the general matrix formulas, users can readily calculate the coefficients of both partial and semi-partial correlations without computational burden. The package ppcor further provides users with the level of the statistical significance with its test statistic.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.4
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• pp.1-7
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• 2006

A major failure mode for wafer level chip size package (WLCSP) is thermo-mechanical fatigue of solder joints. The mechanical strains and stresses generated by the coefficient of thermal expansion (CTE) mismatch between the die and printed circuit board (PCB) are usually the driving force for fatigue crack initiation and propagation to failure. In a WLCSP process peripheral or central bond pads from the die are redistributed into an area away using an insulating polymer layer and a redistribution metal layer, and the insulating polymer layer affects solder joints reliability by absorption of stresses generated by CTE mismatch. In this study, several insulating polymer materials were applied to WLCSP to investigate the effect of insulating material. It was found that the effect of property of insulating material on WLCSP reliability was altered with a solder ball layout of package.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.825-831
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• 2006

As an increase of chip complexity and level of chip integration, chip input/output (I/O) pad pitches are also drastically reduced. With arrival of high complexity SoC (System on Chip) and SiP (System in Package) products, conventional horizontal type probe card showed its limitation on probing density for wafer level test. To enhance probing density, we proposed new vertical type probe card that has the $70{\mu}m$ probe needle with tungsten wire in $80{\mu}m$ micro-drilled hole in ceramic board. To minimize alignment error, micro-drilling conditions are optimized and epoxy-hardening conditions are also optimized to minimize planarity changes. To apply wafer level test for target devices (T5365 256M SDRAM), designed probe card was characterized by probe needle tension for test, contact resistance measurement, leakage current measurement and the planarity test. Compare to conventional probe card with minimum pitch of $50{\sim}125{\mu}m\;and\;2\;{\Omega}$ of average contact resistance, designed probe card showed only $22{\mu}$ of minimum pitch and $1.5{\Omega}$ of average contact resistance. And also, with the nature of vertical probing style, it showed comparably small contact scratch and it can be applied to bumping type chip test.

• Industrial Engineering and Management Systems
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• v.11 no.2
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• pp.196-201
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• 2012

This study has developed a packaging criterion to minimize the level of discomfort which drivers using their vehicles for daily life purposes may experience due to ill designed vehicle packaging of mid-size sedan based on users' daily-life scenario. To find out optimal range of packaging dimension criterion, discomfort levels the test participants with different physical conditions suffer while performing various activities were analyzed. One hundred two test participants were carefully selected to represent entire Korean mid-size sedan owner-drivers. They were directed to test drive on the course designed to simulate mid-size sedan daily-usage scenario. At pre-designed locations, each of questions was asked to the test participants to be answered in the form of 10 point discomfort level score. By analyzing the test results, the optimal range for packaging dimensions was defined to be used as a packaging criterion.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.282-285
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• 2007

Smaller size and higher integration of electronic systems make narrower interconnect pitch not only in chip-level but also in package-level. Moreover electronic systems are required to operate in harsher conditions, that is, higher current / voltage, elevated temperature / humidity, and complex chemical contaminants. Under these severe circumstances, electronic components respond to applied voltages by electrochemically ionization of metals and conducting filament forms between anode and cathode across a nonmetallic medium. This phenomenon is called as the electrochemical migration. Many kinds of metal (Cu, Ag, SnPb, Sn etc) using in electronic packages are failed by ECM. Eutectic SnPb which is used in various electronic packaging structures, that is, printed circuit boards, plastic-encapsulated packages, organic display panels, and tape chip carriers, chip-on-films etc. And the material for soldering (eutectic SnPb) using in electronic package easily makes insulation failure by ECM. In real PCB system, not only metals but also many chemical species are included. And these chemical species act as resources of contamination. Model test systems were developed to characterize the migration phenomena without contamination effect. The serpentine-shape pattern was developed for analyzing relationship of applied voltage bias and failure lifetime by the temperature / humidity biased(THB) test.

• Journal of Korean Biological Nursing Science
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• v.24 no.4
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• pp.235-242
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• 2022

Purpose: To investigate associations of perceived stress level, serum cortisol level, and telomere length of community-dwelling adults in Korea. Methods: Data of a total of 135 community-dwelling adults aged over 40 years living in D metropolitan city from December 2020 to March 2021 were collected. Perceived stress level over the past month were measured using the Perceived Stress Score. Serum cortisol level was analyzed using a chemiluminescent microparticle immunoassay. Telomere length was determined using quantitative real-time polymerase chain reaction. The statistical package SPSS 23.0 was used to perform Chi-square test, independent t-test, and Pearson's correlation coefficient analysis. Results: There was no association between perceived stress and serum cortisol level (r = .07, p= .402). Serum cortisol level was not significantly associated with telomere length either (r = -.15, p= .081). However, the higher the perceived stress level, the shorter the telomere length (r= -.29, p= .001). Conclusion: These results suggest that perceived stress might induce physiological stress, which might partially affect gene biology. Further longitudinal research is needed to investigate the effect of perceived stress on telomere length. Intervention for relieving stress should be included in stabilizing the genetic environment of adults.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.89-94
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• 2005

The compression strength of corrugated fiberboard container for packaging the agricultural products rapidly decreases because of various environmental conditions during distribution of unitized products. Among various environmental conditions, the main factors affecting the compression strength of corrugated fiberboard are absorption of moisture, long-term accumulative load, and fatigue caused by shock and vibration. An estimated rate of damage for fruit during distribution is about from 30 to 40 percent owing to the shock and vibration. This study was carried out to characterize the durability of corrugated fiberboard container for packaging the fruit and vegetables under simulated transportation environment. The vibration test system was constructed to simulate the land transportation using truck. After the package with corrugated fiberboard container was vibrated by vibration test system at various experimental conditions, the compression test for the package was performed. The compression strength of corrugated fiberboard container decreased with loading weight and vibrating time. The multiple nonlinear regression equation for predicting the decreasing rate of compression strength of corrugated fiberboard containers were developed using four independent variables such as input acceleration level, input frequency, loading weight and vibrating time. The influence of loading weight on the decreasing rate of corrugated fiberboard container was larger than other variables.