• Journal of the Microelectronics and Packaging Society
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• v.25 no.1
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• pp.41-45
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• 2018

As the size of semiconductor chip shrinks, the electronic industry has been paying close attention to fan-out wafer level packaging (FO-WLP) as an emerging solution to accommodate high input and output density. FO-WLP also has several advantages, such as thin thickness and good thermal resistance, compared to conventional packaging technologies. However, one major challenge in current FO-WLP manufacturing process is to control wafer warpage, caused by the difference of coefficient of thermal expansion and Young's modulus among the materials. Wafer warpage induces misalignment of chips and interconnects, which eventually reduces product quality and reliability in high volume manufacturing. In order to control wafer warpage, it is necessary to understand the effect of material properties and design parameters, such as chip size, chip to mold ratio, and carrier thickness, during packaging processes. This paper focuses on the effects of thickness of chip and molding compound on 12" wafer warpage after PMC of EMC using finite element analysis. As a result, the largest warpage was observed at specific thickness ratio of chip and EMC.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.683-690
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• 2004

Garment modeling and simulation is now one of the important elements in broad range of digital contents. Though there have been recent products on garment simulation, general users do not know well enough how to design a virtual costume that meets some requirements about its specific clothing pattern. In particular, Hanbok - the Korean traditional costume - has many different characteristics against western ones in the aspect of its pattern design and of draping. This paper presents a knowledge-driven approach for virtual Hanbok modeling without knowing how to make real Hanbok. First, parameterized knowledge for several fabric types art solicited using visual similarity assessment from simulated and real cloth. Secondly, based on the analysis of designer's knowledge, we defined multi-level adjustment processes of Hanbok measurements with regard to body shape features for different virtual actors. An experimental system is developed as the form of a Maya plug-in and the result shows the applicability of the proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.1-7
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• 2017

The RAR (Reinforced Abutment for Railways) is an economical abutment to reduce the settlement of a transitional zone and horizontal displacement of an abutment by constructing backfill before the abutment. In this paper, the performance of the RAR depending on the pile installation was evaluated using 2D (Dimensional) finite element analysis and compared with the existing abutment (with 5 rows pile). Numerical analysis showed that increasing pile installation is more effective in reducing horizontal displacement and earth pressure than settlement of the transitional zone. The horizontal displacement and earth pressure of the RAR was approximately 26~37% and 59~83% compared to the existing abutment by changing the pile installation. More pile installation led to a greater reduction of the horizontal displacement and earth pressure of the RAR. In addition, the horizontal earth pressure of RAR is influenced considerably by the reinforcement, pile, foundation, and stiffness of the ground.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.208-212
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• 2009

The nano-clay is widely used in polymer-nanocomposites due to the high aspect ratio, heat resistance and nano-scale dimension. In recent researches, the thermal and mechanical properties of polyurethane foam were improved with introducing the nano-clay. In this study, we describe the influence of ultrasonic treatment and content of nano-clay on properties of polyurethane foam. The nano-clay/polyurethane foam were characterized using their recovery time, compressive deflection, cell morphology and tensile test. The ultrasonic treatment was very effective for dispersion of nano-clay. Moreover, we found that introducing over 3 wt% of nano-clay bring the decrease of properties due to the poor dispersion. Expecially, ultrasonically treated 20A/polyurethane foam(1 wt%) showed greatly improved properties, such as homogeneous cell size and good dimension stability. We expect that our results could be applied to insulating materials for construction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.437-441
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• 2014

This paper presents a novel microplatform for high power generation based on reverse electrodialysis. The ideal cation-selective membrane for power generation was realized using geometrically controlled in situ self-assembled nanoparticles. Our proposed membranes can be constructed through a simple and cost-effective process that uses microdroplet control with nanoparticles in a microchannel. Another advantage of our system is that the maximum power and energy conversion efficiency can be improved by changing the geometry of the microchannel and proper selection of the nanoparticle size and material. This proposed platform can be used to supply power sources to other microdevices and contribute to a fundamental understanding of ion transport behavior and the power generation mechanism.

• Journal of the Korean Home Economics Association
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• v.41 no.6
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• pp.1-12
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• 2003

The purpose of this study were to analyze the anthropometric data of feet of Korean women with aging, to categorize the women's foot shapes, and to compare the shoe size according to the foot shapes in order to provide the basic information for more comfortable shoes. Subjects of this study were 181 women over age 20. They were measured with the direct measurement method and the indirect measurement method. 26 items were measured from the right foot and 6 items were taken on foot outline. Factor analysis, cluster analysis, analysis of variance, post-hoc test, and cross tabs were peformed for statistical analysis of the data by SPSS program. There were significant differences in height items, breadth items, girth items, and angle items by subjects' age. The older subjects' feet were wide and thick with big deformity on toes. The arch height of the older ones was low. This implicates that the degree of deformity on toes, the foot ratio, the foot girth, the foot breath and the arch height as well as the foot length are needed to be considered in developing comfortable shoes. Nine foot construction factors were extracted by the factor analysis of anthropometric measurements; foot size factor, heel and instep factor, malleolus lateralis factor, malleolus medialis factor, foot shape factor, shape of toes factor, heel height factor, big toe height factor, and internal factor. On the basis of the cluster analysis, three different foot shapes were categorized. Type 1 was large and wide foot with little deformity on little toe. Type 2 was medium foot with deformation of big toe, and with the lowest arch height. Type 3 was small and narrow foot with the highest arch height. Distribution of shoe size according to the foot shape was analyzed. The ball of foot breath was of wide distribution than the ball of foot girth. This implicates that girth items and breath items of the foot should be enclosed for the same foot length in the shoe sizing system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.81-86
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• 2021

The cosmetic industry is technology-intensive in the field of fine chemistry and continues to grow globally. The functional aspects have been mainly emphasized in the past to increase the market share in these cosmetics industries. Recently, however, efforts have been made to attract the attention of consumers to the visual effects as well as the excellent performance of cosmetics at home and abroad. Accordingly, cosmetic manufacturers are trying various technologies that encapsulate the cosmetic emulsion and modify the shape, color, and texture of the emulsion capsule. The basic and easiest method of encapsulating emulsion is dropping the emulsion through the nozzle from emulsion storage. On the other hand, the existing method of encapsulating emulsion has a limit in reducing the size of the capsule. In this study, the limit was shown by theory and numerical analysis method, and the emulsion encapsulation phenomena occurring in the micro-channel were studied to apply microfluidics as an alternative.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.115-123
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• 2010

Because of development of information technology, moving picture can run various platforms. We should consider and apply users' attitude as well as production technique because convergence between mobile and media technology may be increased full-browsing service using mobile device. Previous research related to production technique in various platforms only focus on video quality and adjustment of screen size. However, besides of technical side, production techniques should be changed such as image production as well as image editing by point of view aesthetic. Mise-en-scene such as camera angle, composition, and lighting is changed due to HD image. Also image production should be changed to a suitable full-browsing service using mobile device. Therefore, we would explore a new suitable production techniques and image editing for smart phone. To propose production techniques for smart phone, we used E-learning production system, which are transition, editing technique for suitable converting system. Such as new attempts are leading to new paradigm and establishing their position by applying characteries such as openness, timeliness to mobile. Also it can be extended individual area and established as expression and play tool.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.53-61
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• 2008

Public Key Broadcast Encryption (PKBE) allows a sender to distribute a message to a changing set of users over an insecure channel. PKBE schemes should be able to dynamically exclude (i.e., revoke) a certain subset of users from decrypting a ciphertext, so that only remaining users can decrypt the ciphertext. Another important requirement is for the scheme to be forward-secrecy. A forward-secure PKBE (fs-PKBE) enables each user to update his private key periodically. This updated private key prevents an adversary from obtain the private key for certain past period, which property is particularly needed for pay-TV systems. In this paper, we present a fs-PKBE scheme where both ciphertexts and private keys are of $O(\sqrt{n})$ size. Our PKBE construction is based on Boneh-Boyen-Goh's hierarchical identity-based encryption scheme. To provide the forward-secrecy with our PKBE scheme, we again use the delegation mechanism for lower level identities, introduced in the BBG scheme. We prove chosen ciphertext security of the proposed scheme under the Bilinear Diffie-Hellman Exponent assumption without random oracles.

• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.12-19
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• 2004

Binding mechanisms of polycyclic aromatic hydrocarbons (PAHs) with a purified Aldrich humic acid (PAHA) and its ultrafiltration (UF) size fractions were investigated. Organic carbon normalized binding coefficient ($K_oc$) values were estimated by both a conventional Stern-Volmer fluorescence quenching technique and a modified fluorescence quenching method. Pyrene $K_oc$ values depended on PAHA concentration as well as freely dissolved pyrene concentration. Such nonlinear sorption-type behaviors suggested the existence of specific interactions. Smaller molecular size PAH (naphthalene) exhibited higher $K_oc$ value with medium-size PAHA UF fractions whereas larger size PAH (pyrene) had higher extent of binding with larger PAHA UF fractions. The inconsistent observation for naphthalene versus pyrene was well explained by size exclusion effect, one of the previously suggested specific mechanisms for PAH binding. In general, the extent of pyrene binding increased with lower pH likely due to the neutralization of acidic functional groups in HS and the subsequent increase in hydrophobic HS region. However, pyrene $K_oc$ results with a large UF fraction (>100K Da) corroborated the existence of the size exclusion effect as demonstrated by an increase in $K_oc$ values at a certain higher pH range. The size exclusion effect appears to be effective only for the specific conditions (HS size or pH) that render HS hole st겨ctures to fit a target PAH.