• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.443-453
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• 2017

In flip chip technology, the conventional solder bump has been replaced with a copper (Cu) pillar bump owing to its higher input/output (I/O) density, finer pitch, and higher reliability. However, Cu pillar bump technology faces several issues, such as interconnect shorting and higher low-k stress due to stiffer Cu pillar structure when the conventional reflow process is used. Therefore, the thermal compression bonding (TCB) process has been adopted in the flip chip attachment process in order to reduce the package warpage and stress. In this study, we investigated the package warpage induced during the TCB process using a numerical analysis. The warpage of the TCB process was compared with that of the reflow process.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1071-1077
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• 2012

Low frequency noises(up to about 200 Hz) such as booming are mainly caused by particular modes, and in general the solutions may be found based on mode controls where conventional methods such as FEM can be used. However, at higher frequencies between 0.3~1 kHz, as the number of modes rapidly increases, radiation characteristics from structures, performances of damping sheets and sound packages may be more crucial rather than particular modes, and consequently the conventional FEM may be less practical in dealing with this kinds of structure-borne problems. In this context, so-called 'mid-frequency simulation model' based on FE-SEA hybrid method is studied and validated to reduce noise in this frequency region. Energy transmission loss(i.e. air borne noise) is also studied. A dash panel component is chosen for this study, which is an important path that transmits both structure-borne and air borne energies into the cavity. Design modifications including structural modifications, attachment of damping sheets and application of different sound packages are taken into account and the corresponding noise characteristics are experimentally identified. It is found that the dash member behaves as a noise path. The damping sheet and sound packages have similar influences on both sound radiation and transmission loss. The comparison between experiments and simulations shows that this model could be used to predict the tendency of noise improvement.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.147-153
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• 2014

The purpose of this paper is to examine the roll damping characteristics by bilge keels on the fishing vessel. Unlike other degree of freedom motions, roll motion is highly nonlinear. However the quantitative evaluation of roll damping combined with waves is very important for the fishing vessel. To reduce roll motion, roll motion stabilizers such as a bilge keel is used due to easy made and cheap cost rather than anti-rolling tank and fin-stabilizer. Authors paid attention to the shape of bilge keel and waves to grasp the roll damping for the fishing vessel and studied about the difference of tendencies of roll angle following the shapes of bilge keel. The model ship was the offshore large purse seiner and four types of bilge keel were used. The data from the experiments were provided and analyzed to investigate the rolling characteristics of the model ship being affected by the wave height, wave period and bilge keel shape. The results of the study showed that three types of the bilge keel have little effective, but only one has an effect on the roll damping. So bilge keel shape and its attachment method need to be a future study for the practical use in fishing vessel.

• Journal of the Korea Society of Computer and Information
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• v.13 no.6
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• pp.173-180
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• 2008

Certified e-Document Authority keep it with protection legal as a system a guarantee and identifies originality of an e-Record, It presume to be authenticity e-Records and contents of an e-Record prove what was not changed. But, e-Records has high medium degree of dependence and loss danger of information has very high problems. In addition, Because correction(attachment and deletion) and a revision of information are easy, a problem for integrity and the originality of an e-Record is caused. Existing system show the following inefficient. For the originality guarantee, an existing e-Documents encryption method accomplishes a encrypted process of a whole document with a symmetric key, if the information revised midway, the whole documents content must accomplish re-scanning and re-encryption process again. To get over such inefficient, this paper maximize efficiency which occurred at the time of partial information revision request by encryption and managing using the link information based on the linkage characteristics of the each page on the registered requested e-Documents, It was able to increase security configuration by minimizing problems on an information exposure through increasing complicated of the key management.

• Imaging Science in Dentistry
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• v.41 no.3
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• pp.115-121
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• 2011

Purpose : This article is to describe a modified device for intraoral radiography which was developed to obtain reproducible radiographic images for assessment of distal osseous defects of the mandibular second molar (2 Mm) after impacted third molar (3 Mm) surgery. Materials and Methods : A commercial available alignment system for posterior region was modified by adding a reference gauge pin (millimetric) and threading a hollow acrylic cylinder at the ring of the radiographic positioner to attach the X-ray collimator. The design included customized resin acrylic stent for the occlusal surface of the 2Mm in maximum intercuspal position, individualizing the biteblock positioner. Periapical radiographs were taken before and after surgical extraction of 3 Mm, employing the radiographic technique of parallelism described by Kugelberg (1986) with this modified film holder and inserting the gauge pin on the deepest bone probing depth point. Results : This technique permitted to obtain standardized periapical radiographs with a moderate to high resolution, repeatability, and accuracy. There was no difference between the measurements on the pre- and post-operative radiographs. This technique allowed better maintenance of the same geometric position compared with conventional one. The insertion of the gauge pin provided the same reference point and localized the deepest osseous defect on the two-dimensional radiographs. Conclusion : This technique allowed better reproducibility in posterior radiographic records (distal surface of 2 Mm) and more accurate measurements of radiographic bone level by the use of a millimetric pin.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.231-234
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• 2011

Recently, the smart RFID tag technology which can measure external changing environment is globally interesting. In this paper, development of the Smart RFID tag using temperature sensor was represented. Smart RFID tag is basically comprised of antenna which has its bandwidth of 13.56Mhz, temperature sensors and data processing controller. Antenna design and smaller PCB production can be used to agri-food wrap. Since the smart RFID tag is distributed as an attachment to agri-food wrap, consumer can check temperature changes in the distribution process. Because temperature change check in real time, food confirm the status of transportation and the freshness. Also, smart RFID tag can be applied to proposed smart refrigerator.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.305-311
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• 2010

iATA (Internet Advanced Technology Attachment) is a block-level protocol developed to transfer ATA commands over TCP/IP network, as an alternative network storage solution to address insufficient storage problem in mobile devices. This paper employs RAID5 distributed storage servers concept into iATA, in which the idea behind is to combine several machines with relatively inexpensive disk drives into a server array that works as a single virtual storage device, thus increasing the reliability and speed of operations. In the case of one machine failed, the server array will not destroy immediately but able to function in a degradation mode. Meanwhile, information can be easily recovered by using boolean exclusive OR (XOR) logical function with the bit information on the remaining machines. We perform I/O measurement and benchmark tool result indicates that additional fault tolerance feature does not delay read/write operations with reasonable file size ranged in 4KB-2MB, yet higher data integrity objective is achieved.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.7
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• pp.1093-1104
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• 2002

In this study, the diffusion phenomenon of casual Hanbok which started in the mid 1990s and has been widely spread ever since with innovative features in design, materials, etc., was reviewed. Through the interviews of 45 People who have worn casual Hanbok the advantages and disadvantages of casual Hanbok related to its innovative characteristics were recorded and analyzed. Through the questionnaires distributed to 482 adults living in Seoul, Busan, and Darjeon, the factors related to the adoption of casual Hanbok were examined. The following are the results from the empirical study. First the adoption of contemporary casual Hanbok is due to the consumers′ positive response to the excellence of casual Hanbok′s various innovative characteristics. What the consumers perceived as innovative characteristics of casual Hanbok in the survey results validated the findings of the depth interview, identifying seven subcategories of the innovative characteristics of casual Hanbok; aesthetics, positive training effect on body and mind, difficulty in we, practicality, psychological attachment for "Our Clothes", economic efficiency, and symbolic compatibility. And consumers who think highly of such spiritual and identity values as national consciousness, nature affiliation, and community consciousness, had high evaluation to casual Hanbok However, consumers′ prejudice against Hanbok that Hanbok is for old people, uncomfortable, and not suitable to modern life, tuned out to have a negative influence on the adoption. From these results, it can be concluded that casual Hanbok of the late 1990s is a fashion with innovative characteristics, different from the one in the l980s worn by the demonstrators of popular movements and democratic movements, and it emerged as a new symbol with the characteristics of cultural movement like community consciousness and nature affiliation.

• Polymer(Korea)
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• v.32 no.5
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• pp.415-420
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• 2008

The porcine small intestinal submucosa (SIS) without immunorejection responses and hyalunonic acid (HA) can be used as biomaterials. In this study, we tried to design and characterize novel sponge. SIS- HA sponge was prepared by freeze-drying after addition 1wt% HA solution into fabricated SIS sponge. Sponge was crosslinked with 1-ethyl-(3-3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) solution with 100mM concentration for 24 hrs and lyophilized. SIS-HA sponge was characterized by scanning electron microscopy and fourier transform infrared spectrometer. And water absorption ability of sponge was evaluated. We seeded NIH/3T3 cells in SIS-HA sponge and cellular attachment was assayed by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltertazolium-bromide (MTT) test. We demonstrated presence of HA in SIS-HA sponge from C-O functional group observed by the FT-IR analysis. Moreover, we confirmed low cytotoxicity and high cell viability of the SIS-HA sponges. Therefore, we could expect that SIS- HA scaffolds are applicable for the tissue regeneration.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.193-198
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• 2019

In smart cities around the world, urban environments have become more convenient due to information and communication technology(ICT). However, extant studies reveal that the level of life satisfaction of citizens has not improved compared to that of the pre-smart city and citizens are skeptical about the role of the smart city. This is largely because local culture and needs were neglected during the planing and development of the smart city. The research was conducted on Cambodia as a pilot site and our findings indicate that middle age group's population is significantly small and the society is at risk of losing its culture. Therefore, this paper opens up various ways of embedding cultural programs using technology in order to pass down cultural heritage to young generation, provide an emotional attachment to the inhabitants and further build up a new phase of cultural legacy. This will engender cultural uniqueness to the city and intrigue tourists around the world resulting in the growth of the tourist industry. This research will contribute locally by providing a sense of community to the public and globally by suggesting applicable methodology to other cities that are under the similar context.