• Journal of Information Technology Services
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• v.13 no.3
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• pp.309-321
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• 2014

Recently, due to the advent of ubiquitous computing and the spread of intelligent portable device such as smart phone, iPad and PDA has been amplified, a variety of services and the amount of information has also increased fastly. It is becoming a part of our common life style that the demands for enjoying the wireless internet are increasing anytime or anyplace without any restriction of time and place. And also, the demands for e-commerce and many different items on e-commerce and interesting of associated items are increasing. Existing collaborative filtering (CF), explicit method, can not only reflect exact attributes of item, but also still has the problem of sparsity and scalability, though it has been practically used to improve these defects. In this paper, using a implicit method without onerous question and answer to the users, not used user's profile for rating to reduce customers' searching effort to find out the items with high purchasability, it is necessary for us to analyse the segmentation of customer and item based on customer data and purchase history data, which is able to reflect the attributes of the item in order to improve the accuracy of recommendation. We propose the method of recommendation system using association rule and weighted preference so as to consider many different items on e-commerce and to refect the profit/weight/importance of attributed of a item. To verify improved performance of proposing system, we make experiments with dataset collected in a cosmetic internet shopping mall.

• Journal of Welding and Joining
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• v.29 no.5
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• pp.95-98
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• 2011

Recently, there is a growing tendency that fine-pitch electronic devices are increased due to higher density and very large scale integration. Finer pitch printed circuit board(PCB) is to be decrease insulation resistance between circuit patterns and electrical components, which will induce to electrical short in electronic circuit by electrochemical migration when it exposes to long term in high temperature and high humidity. In this research, the effect of soldering flux acting as an electrical carrier between conductors on electrochemical migration was investigated. The PCB pad was coated with OSP finish. Sn3.0Ag0.5Cu solder paste was printed on the PCB circuit and then the coupon was treated by reflow process. Thereby, specimen for ion migration test was fabricated. Electrochemical migration test was conducted under the condition of DC 48 V, $85^{\circ}C$, and 85 % relative humidity. Their life time could be increased about 22% by means of removal of flux. The fundamentals and mechanism of electrochemical migration was discussed depending on the existence of flux residues after reflow process.

• Journal of Digital Contents Society
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• v.15 no.6
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• pp.711-719
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• 2014

Along with the advent of ubiquitous computing environment, it is becoming a part of our common life style that the demands for enjoying the wireless internet using intelligent portable device such as smart phone and iPad, are increasing anytime or anyplace without any restriction of time and place. The recommending service becomes a very important technology which can find exact information to present users, then is easy for customers to reduce their searching effort to find out the items with high purchasability in e-commerce. Traditional mining association rule ignores the difference among the transactions. In order to do that, it is considered the importance of type of merchandise or service and then, we suggest a new recommending service using mining sequential pattern based on weight to reflect frequently changing trends of purchase pattern as time goes by and as often as customers need different merchandises on e-commerce being extremely diverse. To verify improved better performance of proposing system than the previous systems, we carry out the experiments in the same dataset collected in a cosmetic internet shopping mall.

• Journal of Welding and Joining
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• v.31 no.5
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• pp.54-58
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• 2013

Joint properties of vehicle ECU (Electric Control Unit) module which was manufactured by using Sn-Cu-Cr-Ca alloy were investigated. A new solder which has a middle melting temperature about $231^{\circ}C$ was fabricated as the type of 300um solder ball and paste type. The prototype modules were made by reflow process and measured spreadability, wettability shear strength and estimated interface reaction. The spreadability of the alloy was about 84% from the measurement of contact angle of the solder ball and the wetting force was measured 2mN. The average shear strength of the module which was manufactured by using the solder paste, was 1.9 $kg/mm^2$. Also, the thickness of IMC(intermetallic compound) was evaluated with various aging temperature and time in order to understand Cr effect on Sn-0.7Cu solder. $Cu_6Sn_5$ IMC was formed between Cu pad and the solder alloy and the average thickness of the $Cu_6Sn_5$ IMC was measured about 4um and it was about 50% of thickness of $Cu_6Sn_5$ IMC in Sn-0.7Cu. It is expected to have a positive effect on reliability of the solder joint.

• ETRI Journal
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• v.39 no.6
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• pp.866-873
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• 2017

We propose a multilayered-substrate-based power semiconductor discrete device package for a low switching loss and high heat dissipation. To verify the proposed package, cost-effective, low-temperature co-fired ceramic, multilayered substrates are used. A bare die is attached to an embedded cavity of the multilayered substrate. Because the height of the pad on the top plane of the die and the signal line on the substrate are the same, the length of the bond wires can be shortened. A large number of thermal vias with a high thermal conductivity are embedded in the multilayered substrate to increase the heat dissipation rate of the package. The packaged silicon carbide Schottky barrier diode satisfies the reliability testing of a high-temperature storage life and temperature humidity bias. At $175^{\circ}C$, the forward current is 7 A at a forward voltage of 1.13 V, and the reverse leakage current is below 100 lA up to a reverse voltage of 980 V. The measured maximum reverse current ($I_{RM}$), reverse recovery time ($T_{rr}$), and reverse recovery charge ($Q_{rr}$) are 2.4 A, 16.6 ns, and 19.92 nC, respectively, at a reverse voltage of 300 V and di/dt equal to $300A/{\mu}s$.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.11-17
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• 2009

The drop impact reliability comes to be important for evaluation of the life time of mobile electronic products such as cellular phone. The drop impact reliability of solder joint is generally affected by the kinds of pad and reflow number, therefore, the reliability evaluation is needed. Drop impact test proposed by JEDEC has been used as a standard method, however, which requires high cost and long time. The drop impact reliability can be indirectly evaluated by using high speed shear test of solder joints. Solder joints formed on 3 kinds of surface finishes OSP (Organic Solderability Preservation), ENIG (Electroless Nickel Immersion Gold) and ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) was investigated. The shear strength was analysed with the morphology change of intermetallic compound (IMC) layer according to reflow number. The layer thickness of IMC was increased with the increase of reflow number, which resulted in the decrease of the high speed shear strength and impact energy. The order of the high speed shear strength and impact energy was ENEPIG > ENIG > OSP after the 1st reflow, and ENEPIG > OSP > ENIG after 8th reflow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.640-649
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• 2018

This study analyzed the consumer awareness of cycling wear using web mining, one of the big data analysis methods. For this, the texts of postings and comments related to cycling wear from 2006 to 2017 at Naver cafe, 'people who commute by bicycle' were collected and analyzed using R packages. A total of 15,321 documents were used for data analysis. The keywords of cycling wear were extracted using a Korean morphological analyzer (KoNLP) and converted to TDM (Term Document Matrix) and co-occurrence matrix to calculate the frequency of the keywords. The most frequent keyword in cycling wear was 'tights', including the opinion that they feel embarrassed because they are too tight. When they purchase cycling wear, they appeared to consider 'price', 'size', and 'brand'. Recently 'low price' and 'cost effectiveness' have become more frequent since 2016 than before, which indicates that consumers tend to prefer practical products. Moreover, the findings showed that it is necessary to improve not only the design and wearability, but also the material functionality, such as sweat-absorbance and quick drying, and the function of pad. These showed similar results to previous studies using a questionnaire. Therefore, it is expected to be used as an objective indicator that can be reflected in product development by real-time analysis of the opinions and requirements of consumers using web mining.

• Korean Journal of Food Science and Technology
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• v.47 no.4
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• pp.492-498
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• 2015

Testosterone deficiency syndrome (TDS) is normally observed in elderly men and is a clinical and biochemical syndrome, characterized by a decline in plasmic testosterone levels resulting in a significant decrease in quality of life. The aim of this study was to evaluate the effect of a mixed extract of fenugreek seeds and Lespedeza cuneata (YHM) on TDS. Rats were divided into three groups: the negative control, YHM-40 (40 mg/kg), and YHM-80 (80 mg/kg) groups. After 4 weeks of YMH administration, an increase was observed in the plasmic testosterone levels, vastus lateralis muscular strength, forced swimming time, total sperm counts, and motile sperm counts in YHM-40 and YHM-80 groups compared to the negative control group. Moreover, sex hormone binding globulin, the epididymal fat pad, total plasmic cholesterol, and triglyceride levels were significantly decreased in the YHM-fed groups. However, prostate specific antigen, aspartate aminotransferase, and alanine aminotransferase levels did not differ among the groups. These results suggest that YHM may enhance testosterone levels in elderly men and alleviate TDS without common side effects.

• The Research Journal of the Costume Culture
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• v.6 no.3
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• pp.56-72
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• 1998

Vest is a general term for a sleeveless upper garment and it derives from a kolobus of a sleeveless tunic style that was started to be worn as a substitution of a chiton by the peasantry in Greek period. The kolobus started to be called a colobium or a tunica from Roman period and the former was named for a vest style tunica which was worn by the people of the lower classes in early Roman period. Similarly, a German colobium of North Europe which was worn during the same period was the same kind of clothe as the Roman colobium. The colobium came to be worn over a dalmatica as an outer garment by early Christians when it was the Middle Ages, who succeeded the tradition of colobium as they went through ancient Rome, Creek and Byzantine days. North Germans also succeeded the colobium tradition of ancient Germans as it was and so continued to wear it in tight style. The simple vest style of colobium was getting vanished from the mid of the Middle Agnes and a new style of vest named jupon was started to be worn by soldiers. The jupon was to protect soldiers' bodies from either were cold weather or enemies wearing under armors as it was made with double cotton pad by quilt. From 14th century, the jupon began to be worn by not only soldiers but also the humble of lower classes. All the jupon which were made in quilting and padding of that time began to be named a pourpoint by the humble. When Renaissance in 16th century came, the pourpoint began to be developed to an exaggerating body-line style. The neckline of pourpoint was getting highly influenced by Spain and a peacecod-belly of it emphasized the exaggerated masculine beauty of Renaissance by padding in round. The sleeves were puffed out and the whole purpoint was made to expose an inner chemise by slashing vertically or obliquely. But in 17th century, the pourpoint has been changed into more simple style without padding, puffing out and slashing influenced by the citizens' clothes of Netherlands. The pourpoint came to be more comfortable bulky style with short sleeves or sleeveless and straight side lines. The pourpoint in mid 17th century turned to be a bolero jacket style by gradually being tightened. It had been then changed into a vest style with sleeves and worn under an overcoat with the name of vest in the end of 17th century. The early vest was 2∼3 inches les in length than the overcoat and had long sleeves and many ornamental buttons on front. It was also made as a home wear to be worn it alone at home. In 18th century, the length of the vest became shorter compared with that of 17th century and the most important decorative item in clothes. It again came to have complete sleeveless vest style and had very short length reaching waist in the end of 18th century. When it was in 19th century, the vest had developed into more various style and colors and style had been applied to be worn by individuals with their tastes. Around the end of 19th century, the increasing tendency to be casual by industrialization influenced on clothes in all aspects of life and so the male vest has been gradually changed into more casual style. Nowadays, it has been developing into various uses in modern male clothes to show their characters.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.61-66
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• 2012

Chemical Mechanical Planarization (CMP) is a polishing process used in the microelectronic fabrication industries to achieve a globally planar wafer surface for the manufacturing of integrated circuits. Pad conditioning plays an important role in the CMP process to maintain a material removal rate (MRR) and its uniformity. For metal CMP process, highly acidic slurry containing strong oxidizer is being used. It would affect the conditioner surface which normally made of metal such as Nickel and its alloy. If conditioner surface is corroded, diamonds on the conditioner surface would be fallen out from the surface. Because of this phenomenon, not only life time of conditioners is decreased, but also more scratches are generated. To protect the conditioners from corrosion, thin organic film deposition on the metal surface is suggested without requiring current conditioner manufacturing process. To prepare the anti-corrosion film on metal conditioner surface, vapor SAM (self-assembled monolayer) and FC (Fluorocarbon) -CVD (SRN-504, Sorona, Korea) films were prepared on both nickel and nickel alloy surfaces. Vapor SAM method was used for SAM deposition using both Dodecanethiol (DT) and Perfluoroctyltrichloro silane (FOTS). FC films were prepared in different thickness of 10 nm, 50 nm and 100 nm on conditioner surfaces. Electrochemical analysis such as potentiodynamic polarization and impedance, and contact angle measurements were carried out to evaluate the coating characteristics. Impedance data was analyzed by an electrical equivalent circuit model. The observed contact angle is higher than 90o after thin film deposition, which confirms that the coatings deposited on the surfaces are densely packed. The results of potentiodynamic polarization and the impedance show that modified surfaces have better performance than bare metal surfaces which could be applied to increase the life time and reliability of conditioner during W CMP.