• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.81-88
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• 2019

In this study, the effects of graphene oxide (GO) addition on electromigration (EM) lifetime of Sn-3.0Ag-0.5Cu Pb-free solder joint between a ball grid array (BGA) package and printed circuit board (PCB) were investigated. After as-bonded, $(Cu,Ni)_6Sn_5$ intermetallic compound (IMC) was formed at the interface of package side finished with electroplated Ni/Au, while $Cu_6Sn_5$ IMC was formed at the interface of OSP-treated PCB side. Mean time to failure of solder joint without GO solder joint under $130^{\circ}C$ with a current density of $1.0{\times}10^3A/cm^2$ was 189.9 hrs and that with GO was 367.1 hrs. EM open failure was occurred at the interface of PCB side with smaller pad diameter than that of package side due to Cu consumption by electrons flow. Meanwhile, we observed that the added GO was distributed at the interface between $Cu_6Sn_5$ IMC and solder. Therefore, we assumed that EM reliability of solder joint with GO was superior to that of without GO by suppressing the Cu diffusion at current crowding regions.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.629-632
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• 1992

This paper deals with Digital Protection System which has been developed at R & D Center of HYUNDAI Electrical Engineering Co.. This system consists of supervisory control part and digital measuring are protection units. RS-485 network connects the units to supervisory control part. This paper go into detail about the specification of each part and the analysis results of digital measuring and protection unit.

• Journal of the Korean Mathematical Society
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• v.53 no.1
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• pp.187-199
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• 2016

The r-ary number sequences given by $$(b^{(r)}_n)_{n{\geq}0}=\Large{\frac{1}{(r-1)n+1}}(^{rn}_n)$$ are analogs of the sequence of the Catalan numbers ${\frac{1}{n+1}}(^{2n}_n)$. Their history goes back at least to Lambert [8] in 1758 and they are of considerable interest in sequential testing. Usually, the sequences are considered separately and the generalizations can go in several directions. Here we link the various r first by introducing a new combinatorial structure related to GR trees and then algebraically as well. This GR transition generalizes to give r-ary analogs of many sequences of combinatorial interest. It also lets us find infinite numbers of combinatorially defined sequences that lie between the Catalan numbers and the Ternary numbers, or more generally, between $b^{(r)}_n$ and $b^{(r+1)}_n$.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2017.11a
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• pp.1373-1373
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• 2017

오늘날 ICT는 타산업과의 융합을 통한 경제성장의 핵심수단 및 사회이슈를 해결할 도구로서 인식되고 있으나, 우리나라의 R&D 성과활용은 기술개발의 성공률에 비해 매우 낮은 수준이다. 이는 R&D의 공급자인 연구자 중심의 기획, 기술개발 추진이 주된 원인으로 지적되고 있다. 이에 따라, 수요자의 요구에 부합되는 시장성 있는 제품 서비스 구현이 R&D 추진의 중요한 요소로 대두되고 있으며, 기획에서부터 실사용자의 요구사항을 도출하고 기술개발과정에서 지속적으로 사용자의 피드백을 통해 수정해 나가는 리빙랩 방식의 적용이 절실히 필요한 상황이다. 그러나, 그동안 리빙랩 R&D는 사회문제해결형 또는 지역환경개선형에 집중해서 추진되어 왔다. 본 논문에서는 중소기업 R&D사업에의 리빙랩 도입 방안에 대해 검토해보고 이를 통해 기술개발 결과물의 사업화 가능성을 향상시키기 위한 효율적인 R&D 추진방안에 대해 제안하고자 한다.

• The Journal of Korean Physical Therapy
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• v.21 no.2
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• pp.39-45
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• 2009

Purpose: The purpose of this study was to determine correlations between the Berg Balance Scale (BBS), Functional Reach Test (FRT), Timed Up & Go (TUG), Motor-Free Visual Perception Reach Test Vertical format (MVPT-V), Functional Independence Measure (FIM). Methods: The subjects used in this study were 35 stroke patients from Cheongju ST. Mary's hospital. Balance was measured by BBS, FRT. Functional mobility was measured by TUG. Visual perception was measured by MVPT-V. FIM was used to evaluate the activities of daily living. Data was analyzed using pearson product correlation. The TUG and MVPT-V index were analyzed by linear regression. Results: There was a statistically significant difference between FRT and BBS (r=0.89, p<0.01), FIM (r=0.74, p<0.05), MVPT-V (r=0.40, p<0.05), and TUG (r=-0.36, p<0.05). There was significant statistical differences between TUG and MVPT-V (r=-0.64, p<.01). However, statistically significant differences were observed between BBS and FIM (r=0.79, p<0.01). The visual close item of the MVPT-V showed the strongest variance in predicting TUG. Conclusion: The use of both quantitative and qualitive scales was shown to be a good measuring instrument for the classification of general clinical performances of stroke patients. In particular, the results suggest that the visual perception test may be able to predict functional locomotion in stroke patients.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.363-367
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• 2015

This paper reports on thermally adjusted graphene oxide (GO) as the hole transport layer (HTL) for organic light-emitting diodes (OLEDs). GO is generally not suitable for HTL of OLEDs because of intrinsic specific resistance. In this paper, the specific resistance of GO is adjusted by the thermal annealing process. The optimum specific resistance of HTL is found to be $10^2{\Omega}{\cdot}m$, and is defined by the maximum current efficiency of OLEDs, 2 cd/A. In addition, the reasons for specific resistance change are identified by x-ray photoelectron spectroscopy (XPS). First, the XPS results show that several functional groups of GO were detached by thermal energy, and the amount of epoxide changed substantially following the temperature. Second, the full width at half maximum (FWHM) of the C-C bond decreased during the process. That means the crystallinity of the graphene improved, which is the scientific basis for the change in specific resistance.

• Physical Therapy Korea
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• v.11 no.1
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• pp.27-34
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• 2004

This study aims to compare the relationship between the Berg Balance Scale (BBS) scores, Timed Up & Go (TUG), Functional Independent Measure (FIM), and subject characteristics. All of the 18 subjects were women between the ages of 68 and 91 (mean=80.2, SD=5.43), and they all lived at the nursing home in Wonju. Balance was measured using BBS, and functional mobility was measured using TUG. FIM was used to evaluate functional independence. Data were analyzed using Spearman correlation. Statistically significant differences were noted between BBS and TUG (r=-.486, p<.05). There were no significant statistical differences between total FIM and BBS, TUG. The FIM items "locomotion" and "communication" showed significant statistical differences between BBS and TUG. The results suggest that FIM may be able to predict dangerous falls in elderly people.

• Membrane and Water Treatment
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• v.13 no.3
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• pp.121-128
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• 2022

A tremendous amount of energy resources is being wasted in cleaning wastewater to save the environment across the globe. Several different procedures are commercially available to process wastewater. In this work, membrane filtration technique is used to treat the textile wastewater because of its cost effectiveness and low environmental impacts. Mixed Matrix Membrane (MMM) consist of Polyvinyl Alcohol (PVA) in which Graphene Oxide (GO) was added as a filler material. Five different membranes by varying the quantity of GO were prepared. The prepared membrane has been characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD), Fourier Transformed Infrared Spectroscopy (FTIR) and Water Contact Angle (WCA). The prepared membranes have been utilized to treat textile wastewater. The synthesized membranes are used for the elimination of total dissolve solids (TDS), total suspended solids (TSS), Methylene blue (MB) dye and copper metallic ions from textile wastewater. It is concluded that amount of GO has direct correlation with the quality of wastewater treatment. The maximum removal of TDS, TSS, MB and copper ions are found to be 7.42, 23.73, 50.53 and 64.5% respectively and are achieved by 0.02 wt% PVA-GO membrane.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.683-690
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• 2003

This purpose of this research is an attempt to measure and comparatively analyze the efficiencies and RTS(Returns to Scale) using panel data of OECD countries including Korea. In order to achieve this purpose, at first this study used efficient production frontier estimation combined with DEA for obtaining parameter estimates of a efficient production frontier. secondly using estimated results, measured R&D productivity and RTS(Returns to Scale) on all of the OECD countries. thirdly using time-series data related to R&D activity of korea, measured R&D productivity and RTS(Returns to Scale). Finally based on the results of R&D productivity and RTS(Returns to Scale) using efficient production frontier, some policy implications for enhancing the R&D competitiveness and the technological capabilities are discussed.

• The Plant Pathology Journal
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• v.29 no.3
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• pp.249-259
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• 2013

Burkholderia glumae causes rice grain rot and sheath rot by producing toxoflavin, the expression of which is regulated by quorum sensing (QS). The QS systems of B. glumae rely on N-octanoyl homoserine lactone, synthesized by TofI and its cognate receptor TofR, to activate the genes for toxoflavin biosynthesis and an IclR-type transcriptional regulator gene, qsmR. To understand genome-wide transcriptional profiling of QS signaling, we employed RNAseq of the wild-type B. glumae BGR1 with QS-defective mutant, BGS2 (BGR1 tofI::${\Omega}$) and QS-dependent transcriptional regulator mutant, BGS9 (BGR1 qsmR::${\Omega}$). A comparison of gene expression profiling among the wild-type BGR1 and the two mutants before and after QS onset as well as gene ontology (GO) enrichment analysis from differential expressed genes (DEGs) revealed that genes involved in motility were highly enriched in TofI-dependent DEGs, whereas genes for transport and DNA polymerase were highly enriched in QsmR-dependent DEGs. Further, a combination of pathways with these DEGs and phenotype analysis of mutants pointed to a couple of metabolic processes, which are dependent on QS in B. glumae, that were directly or indirectly related with bacterial motility. The consistency of observed bacterial phenotypes with GOs or metabolic pathways in QS-regulated genes implied that integration RNAseq with GO enrichment or pathways would be useful to study bacterial physiology and phenotypes.