• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.83-90
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• 2017

In this paper, we evaluated the solderability of thin electroless nickel-electroless palladium-immersion gold (ENEPIG) plating layer for fine-pitch package applications. Firstly, the wetting behavior, interfacial reactions, and mechanical reliability of a Sn-3.0Ag-0.5Cu (SAC305) solder alloy on a thin ENEPIG coated substrate were evaluated. In the wetting test, maximum wetting force increased with increasing immersion time, and the wetting force remained a constant value after 5 s immersion time. In the initial soldering reaction, $(Cu,Ni)_6Sn_5$ intermetallic compound (IMC) and P-rich Ni layer formed at the SAC305/ENEPIG interface. After a prolonged reaction, the P-rich Ni layer was destroyed, and $(Cu,Ni)_3Sn$ IMC formed underneath the destroyed P-rich Ni layer. In the high-speed shear test, the percentage of brittle fracture increased with increasing shear speed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.217-226
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• 2018

Since the sides of a vehicle are designed asymmetrically unlike its front or rear, the degree of deformation of the car body greatly differs depending on the site of collision if a broadside collision takes place. When elastic deformation and plastic deformation occur in the car body occur due to a collision, the kinetic energy is absorbed into the body, and the momentum decreases. Generally, an analysis of traffic accidents analyzes the vehicle's behavior after a collision by the law of momentum conservation and corrects the error of the amount of energy absorption due to the deformation of the car body, applying a restitution coefficient. This study interpreted a finite element vehicle model applying the structure of the car body and the material properties of each part with LS-DYNA, analyzed the result and drew the restitution coefficient and the depth of penetration according to the contact area of the vehicle in a broadside collision between an SUV and a passenger car. When the finally calculated restitution coefficient and depth of penetration were applied to the examples of the actual traffic accidents, there was an effect on the improvement of the error in the result. It was found that when the initial input value, drawn using the finite element analysis model, it had a higher reliability of the interpretation than that of the existing analysis techniques.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.1 s.307
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• pp.1-8
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• 2006

This thesis proposes Arithmetic Shift Register(ASR) which can be used as pseudo random number generator. Arithmetic Shift. Register is defined as progression that multiplies random number D , not 0 or 1 at initial value which is not 0, and it is represented as ASR-D in this thesis. Irreducible polynomial that t which makes $'D^k=1'$ satisfies uniquely as $'t=2^n-1'$ over. $GF(2^n)$ is the characteristic polynomial of ASR-D , and the cycle of Arithmetic Shift Register has maximum cycle as $'2^n-1'$. Galois Linear Feedback Shift Register corresponds to ASR-2-1. Therefore, Arithmetic Shift Register proposed in this thesis generalizes Galois Linear Feedback Shift Register. Linear complexity of ASR-D over$GF(2^n)$ is $'n{\leq}LC{\leq}\frac{n^2+n}{2}'$ and in comparison with existing Linear Feedback Shift Register stability is high. The Software embodiment of arithmetic shift register proposed in this thesis is efficient than that of existing Linear Shift Register and hardware complexity is equal. Arithmetic shift register proposed in this thesis can be used widely in various fields such as cipher, error correcting codes, Monte Carlo integral, and data communication etc along with existing linear shift register.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.245-253
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• 2020

This study is a longitudinal analysis of the life satisfaction of Generation X and Generation Y, with different historical backgrounds, growth backgrounds, values, and lifestyles, using data from the Korean Welfare Panel(KOWEPS). The research data is from the KOWEPS 1st year(2006) to 14th year(2019), out of 27,301 people, who conducted life satisfaction from the latest 12th to 14th year, and the responses were properly answered data from 3 years of 2,492 were used. As a result of the study, the higher the life satisfaction of both Generation X and Generation Y, the more the life satisfaction slowly increases at a slower rate as time passes. In addition, in terms of life satisfaction and rate of change, the initial value of life satisfaction was higher as the living satisfaction increased in both Generation X and Generation Y, but in the case of Generation X, the higher living satisfaction, the lower the rate of change in life satisfaction for 3 years by .327, in the case of Generation Y, the rate of change in life satisfaction was not affected. Finally, in the model of this study, a partial mediation of health condition was established between living satisfaction and life satisfaction tendency. Living satisfaction was analyzed to have a direct effect on life satisfaction and at the same time indirectly with a health condition as a parameter.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.785-790
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• 2015

As an alternative to large-scale clear cutting silviculture, strip clear cutting (SC) is being considered as a system compatible with ecological conservation and forest regeneration. In South Korea, application and effectiveness of SCC in varying forest types were rarely found. In this study, under the subject of strip clear cutting lands of pinus densiflora forest at Samcheok, Gangwon-do Province, the developmental aspect of low vegetation prior to and after deforestation and the correlation between environmental factor and pine regeneration were analyzed. The cover rate of understory vegetation was appeared to be increased after deforestation and rapidly increased two years after deforestation, and it was evaluated to be affected by vigorous tree species and photophilic species. From the perspective of relative importance value, Quercus mongolica, Artemisia keiskeana, and Rubus crataegifolius that influence the cover rate showed the inclination of continuous growth. The diversity of species showed increment inclination as well due to introduction and settlement of early transient species. As a result of analyzing the correlation between vegetation and environmental factor and generation of pine tree size, the soil exposure rate, intensity of light, and canopy openness showed positive relationship, and the understory vegetation cover and woody debris cover rate showed negative relationship.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.139-150
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• 2010

Recently, full-scale research about a passenger tube train system is being progressed as a next-generation transportation system in Korea in light of global green technology. The Korea Railroad Research Institute (KRRI) has commenced official research on the construction of a tube train system. In this paper, we studied various parameters of the tube train system such as the internal tube pressure, blockage ratio, and operating speed through computational analysis with a symmetric and elongated vehicle. This study was about the aerodynamic characteristics of a tube train that operated under standard atmospheric pressure (open field system, viz., ground) and in various internal tube environments (varying internal tube pressure, blockage ratio, and operating speed) with the same shape and operating speed. Under these conditions, the internal tube pressure was calculated when the energy efficiency had the same value as that of the open field train depending on various combinations of the operating speed and blockage ratio (the P-D relation). In addition, the dependence of the relation between the internal tube pressure and the blockage ratio (the P-${\beta}$ relation) was shown. Besides, the dependence of the relation between the total drag and the operating speed depending on various combinations of the blockage ratio and internal tube pressure (the D-V relation) was shown. Also, we compared the total (aerodynamic) drag of a train in the open field with the total drag of a train inside a tube. Then, we calculated the limit speed of the tube train, i.e., the maximum speed, for various internal tube pressures (the V-P relation) and the critical speed that leads to shock waves under various blockage ratios, which is related to the efficiency of the tube train (the critical V-${\beta}$ relation). Those results provide guidelines for the initial design and construction of a tube train system.

• Journal of The Korean Society of Clinical Toxicology
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• v.14 no.1
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• pp.16-25
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• 2016

Purpose: Patients suffering from acute poisoning by different substances often visit the emergency department (ED) and receive various prognoses according to the toxic material and patients' condition. Hyperlactatemia, which is an increased blood lactate level that generally indicates tissue hypoperfusion, is commonly utilized as a prognostic marker in critically ill patients such as those with sepsis. This study was conducted to investigate the relationships between blood lactate and clinical prognosis in acute poisoned patients. Methods: This retrospective study was conducted from January 2013 to June 2014 at a single and regional-tertiary ED. We enrolled study patients who were examined for blood test with lactate among acute intoxicated patients. The toxic materials, patient demographics, laboratory data, and mortalities were also reviewed. Additionally, we analyzed variables including blood lactate to verify the correlation with patient mortality. Results: A total of 531 patients were enrolled, including 24 (4.5%) non-survivors. Patient age, Glasgow coma scale (GCS), serum creatinine (Cr), aspartate transaminase (AST), and serum lactate differed significantly between survivors and non-survivors in the binary logistic regression analysis. Among these variables, GCS, AST, and lactate differed significantly. The median serum lactate levels were 2.0 mmol/L among survivors and 6.9 mmol/L among non-survivors. The AUC with the ROC curve and odds ratio of the initial serum lactate were 0.881 and 3.06 (0.89-8.64), respectively. Conclusion: Serum lactate was correlated with fatalities of acute poisoning patients in the ED; therefore, it may be used as a clinical predictor to anticipate their prognoses.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.493-500
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• 2019

In this study, sensitivity analysis of sediment transport scaling factors in Delft3D-Morphology was performed to examine the effect those parameters on simulation results of cross-shore profile changes. For numerical experiments, one-year wave time series data which were observed in 2018 on the Maengbang coast in Gangwon prefecture were applied as external force. Bathymetric data observed in January and October of the same year were used as initial bathymetric data and annual bathymetric change data, respectively. The simulation performance of the model was evaluated based on the Brier Skill Score index for each part by dividing an arbitrary cross section within the calculation domain into the onshore and offshore parts. As a result, it was found thet the f_BED variable has a slight effect on the simulation results. The f_BEDW and f_SUSW variables show good simulation performance in onshore part when the value less than 0.5 is applied and vice versa. Among the experimental conditions, the optimal combinations of variables are f_BED = 1.0, f_BEDW = 1.0, f_SUSW = 0.1 for the onshore region and f_BED = 1.0, f_BEDW = 1.0, f_SUSW = 0.5 for the offshore region. However, since these combinations were derived based on the observation data on Maengbang beach in 2018, users should be careful when applying those results to other areas.

• Korean Journal of Food Science and Technology
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• v.52 no.4
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• pp.396-402
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• 2020

In order to investigate the changes in the quality attributes during the storage of dry-milled rice flour, two flour samples were obtained from two rice varieties (Hangaru (HG), Samkwang (SK)). These samples were stored at 4℃ and room temperature, respectively, and we analyzed the initial rice flour moisture content and chemical properties. The changes in the rice flour pasting and quality properties during storage were measured for 12 months. Our results showed that HG exhibited better pasting properties than SK, while the fat acidity of HG rapidly increased at room temperature, resulting in short shelf-life. However, the low-temperature (4℃) storage of dry-milled rice flour could reduce the change in the free fatty acid values of both samples. Therefore, low-temperature storage seems to contribute not only to an increased rice flour shelf-life by reducing the fatty acid value changes but also to a reduction in the changes in pasting properties.

• Ecology and Resilient Infrastructure
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• v.5 no.3
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• pp.111-117
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• 2018

Disinfection of ballast water using chlorine dioxide was investigated under various initial microorganism contents, dose concentrations and pH values. Kinetics of microorganism inactivation and byproduct generation of chlorine dioxide treatment were compared with the chlorine treatment. Results of treatments with chlorine dioxide concentrations of 0 to $10mg\;Cl_2/L$ showed that The optimum concentration of chlorine dioxide required for disinfection of ballast water was 1 mg/L. The difference among the second order reaction constants for bacterial disinfection at pH 7.2 to 9.2 for chlorine dioxide was less than 5% for both bacteria. This result implied that the bactericidal effects of chlorine dioxide was independent of the pH in the examined range. On the other hand, the inactivation kinetics of chlorine for E. coli and Enterococcus decreased by 17% and 25%, respectively, when pH increased from 7.2 to 9.2. The bactericidal power of chlorine dioxide was superior to sodium hypochlorite above pH 8.2, the average pH value of sea water. Furthermore, treatments of chlorine dioxide generated less harmful byproducts than chlorine and had a long-term disinfection effect on bacteria and phytoplankton from the results of experiment for 30 days. Chlorine dioxide would be a promising alternative disinfectant for ballast water.