• Journal of Digital Convergence
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• v.16 no.12
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• pp.505-510
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• 2018

This study aimed to compare the elimination effect of dental plaque between general toothbrushes and chewing toothbrushes, so as to investigate whether the chewing toothbrushes have the practicality as the alternatives of general toothbrushes and their utilities in the real life. The study subjects were 30 healthy adults in their 20s who maintained the good dental condition over 16 teeth without systemic diseases, and the decline rates of dental plaque index after usages of general and chewing toothbrushes were calculated. Upon the comparisons of dental plaque decline rates before and after the usages of general and chewing toothbrushes, PHI index was declined from 7.02 to 1.91 in case of the general toothbrush demonstrating dental plaque decline by 72.79%, while it was declined from 6.72 to 4.08 in the chewing toothbrush demonstrating decline by 39.29%. Currently, a variety of dental care items are available in the Korean market, hence, various studies are required on the dental care items so as for the people to properly choose the items.

• Journal of the Korean Society of Radiology
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• v.85 no.1
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• pp.184-196
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• 2024

Purpose We investigated potentially promising imaging findings and their combinations in the evaluation of cognitive decline. Materials and Methods This retrospective study included 138 patients with subjective cognitive impairments, who underwent brain MRI. We classified the same group of patients into Alzheimer's disease (AD) and non-AD groups, based on the neuropsychiatric evaluation. We analyzed imaging findings, including white matter hyperintensity (WMH) and cerebral microbleeds (CMBs), using the Kruskal-Wallis test for group comparison, and receiver operating characteristic (ROC) curve analysis for assessing the diagnostic performance of imaging findings. Results CMBs in the lobar or deep locations demonstrated higher prevalence in the patients with AD compared to those in the non-AD group. The presence of lobar CMBs combined with periventricular WMH (area under the ROC curve [AUC] = 0.702 [95% confidence interval: 0.599-0.806], p < 0.001) showed the highest performance in differentiation of AD from non-AD group. Conclusion Combinations of imaging findings can serve as useful additive diagnostic tools in the assessment of cognitive decline.

• Information Systems Review
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• v.24 no.4
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• pp.41-54
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• 2022

Despite the recent rapid advancement of science and technology, we have been experiencing the decline in productivity since the 2000s. This study aims to investigate the decline at both industry and firm levels, by looking at the emergence and growth of large firms such as Amazon, Alphabet, and Apple and M&A trends. Following the results of previous studies, our results show that productivity at industry level has decreased since the 2000s. Particularly, in the period after 2011, the deterioration of allocative efficiency due to the large firms and the decline in the growth rate of surviving firms in the industry with low ratio of large firms contributed to the productivity decline. On the other hand, our analysis at firm level demonstrates that the productivity of firms that acquired IT firms improved over the entire period. While M&As have a positive impact on productivity, M&As with a demand-side motive such as market penetration and expansion of channels have a relatively larger impact than the ones for production or operation efficiency. Our results also suggest that the higher the proportion of large firms in a specific industry, the lower the productivity of individual firms in the same industry. Overall, given that the industry's structural changes for digital transformation tends to strengthen the growth of large firms, our findings have significant implications by empirically identifying the relationships of the emergence of large firms, the acquisition of IT/Non-IT firms, and motivations for M&As to firm/industry productivity.

• 대한예방의학회:학술대회논문집
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• 2005.10a
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• pp.379-379
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• 2005

• 프린팅코리아
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• s.8
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• pp.146-149
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• 2003

정보경제(Information Economy), 이른바 디지털경제는 최상의 수준에 와 있는 걸로 보인다. 가정에서 그리고 일터에서 우리는 수많은 정보환경에 휩싸여 살아간다. 그리고 우리는 이러한 것들을 당연한 것으로 받아들이고 만끽하면서 생활한다. 그러면서 중요한 사실 한가지를 잊고 있는데, 정보경제 역시 라이프사이클을 따른다는 점이다. 모든 경제법칙이 그러하듯 정보경제 역시 탄생(gestation), 성장(growth), 성숙(maturity), 쇠퇴(decline)의 흐름을 따를 수 밖에 없다. 그렇다면, 지금 우리는 어디쯤 가고 있는 걸까?

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.613-618
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• 2004

Is confirming safety of derailment when wish to develop new vehicles or upgrade running speed of vehicles. This means the measure of wheel load and lateral force that act between wheel and rail. So far, problem in continuous measuring method of derailment coefficient was sensitivity decline and noise growth. This research supplemented these problems by composition of new bridge circuit.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.57
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• pp.41-49
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• 2000

This paper investigates the relation between operating performance and initial underpricing of companies that go public. A significant decline in operating performance subsequent to the initial public offering(IPO) is found. Additionally there is a significant positive relation between post-IPO operating performance and the level of initial underpricing.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2005.12a
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• pp.132-133
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• 2005

• The Magazine of the IEIE
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• v.28 no.4
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• pp.89-96
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• 2001

The LCD monitor market enjoyed rapid growth in 1999 but only experienced modest growth in 2000. It is now poised for rapid growth from 2001 to 2005 as prices and costs decline. Price reductions will enable LCD monitors to move beyond limited vertical markets and extend into the broader consumer markets. This article will examine the future outlook for LCD monitors and provide a growth forecast.

• Membrane and Water Treatment
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• v.2 no.3
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• pp.147-158
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• 2011

Membrane distillation process was used for desalination of hot (333 K) geothermal water, which was applied in the plant producing heating water. The investigated water contained 120 g salts/$dm^3$, mainly NaCl. The mineral composition was studied using an ion chromatography method. The obtained rejection of solutes was closed to 100%, but the small amounts of $NH_3$ also diffused through the membrane together with water vapour. However, the composition of obtained distillate allowed to use it as a makeup water in the heating water system. The geothermal water under study was concentrated from 120 to 286 g NaCl/$dm^3$. This increase in the solution concentration caused the permeate flux decline by a 10-20%. The geothermal water contained sulphates, which was subjected to two-fold concentration to achieve the concentration 2.4-2.6 g $SO{_4}{^{2-}}/dm^3$ and the sulphates then crystallized in the form of calcium sulphate. As a results, an intensive membranes scaling and the permeate flux decline was observed. The XRD analysis indicated that beside the gypsum also the NaCl crystallites were deposited on the membrane surfaces. The fresh geothermal water dissolved the mixed $CaSO_4$ and NaCl deposit from the membrane surface. This property can be utilized for self-cleaning of MD modules. Using a batch feeding of MD installation, the concentration of geothermal water was carried out over 800 h, without significant performance losses.