• 인터넷정보학회논문지
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• 제14권4호
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• pp.91-100
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• 2013

최근 많은 기업들이 도입하는 온라인 브랜드 커뮤니티는 기업 혁신에 도움이 될 고객의 의견을 수집하는 데 유용하게 활용되고 있다. 본 논문은 온라인 브랜드 커뮤니티에 게시되는 다양한 의견들 중 부정적 감정을 담고 있는 고객의견이 기업 혁신에 기여하는데 미치는 영향력을 분석하였다. 이를 위해 먼저 부정적 감정을 Fear, Anger, Shame, Sadness, Frustration의 총 다섯 가지 세분화된 감정으로 분류하고 WordNet과 SentiWordNet을 기반으로 부정적 감정에 대한 감정 어휘군을 구축하였다. 실험을 위해 본 연구에서는 스타벅스의 브랜드 커뮤니티인 MyStarbucksIdea.com에서 81,534건의 고객의견을 수집하였으며 부정적 감정 어휘군을 활용하여 각 고객의견 내 부정적 감정 정보를 추출하였다. 부정적 감정의 유무, 빈도, 강도의 세 가지 측면에 따른 기업 혁신에 대한 영향력을 분석한 결과, 부정적 감정이 담긴 고객의견이 기업 혁신에 유의미한 영향력을 미치는 것으로 나타났으며 부정적 감정 중, Frustration과 Sadness의 감정이 기업 혁신에 긍정적인 영향을 가지고 있음을 확인할 수 있었다.

• ETRI Journal
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• 제38권4호
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• pp.634-644
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• 2016

Channel-based radio-frequency fingerprinting such as a channel impulse response (CIR), channel transfer function (CTF), and frequency coherence function (FCF) have been recently proposed to improve the accuracy at the physical layer; however, their empirical performance, advantages, and limitations have not been well reported. This paper provides a comprehensive empirical performance evaluation of RF location fingerprinting, focusing on a comparison of received-signal strength, CIR-, CTF-, and FCF-based fingerprinting using the weighted k-nearest neighbor pattern recognition technique. Frequency domain channel measurements in the IEEE 802.11 band taken on a university campus were used to evaluate the accuracy of the fingerprinting types and their robustness to human-induced motion perturbations of the channel. The localization performance was analyzed, and the results are described using the spatial and temporal radio propagation characteristics. In particular, we introduce the coherence region to explain the spatial properties and investigate the impact of the Doppler spread in time-varying channels on the time coherence of RF fingerprint structures.

• 대한기계학회논문집A
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• 제33권11호
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• pp.1233-1238
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• 2009

This study analyzed the characterization of high temperature strength of $Si_3N_4$ composite ceramics additive based on variations in the amount of nano colloidal $SiO_2$ added. Semi-elliptical cracks about 100 ${\mu}m$ length were obtained from a Vickers indenter using a load of 24.5 N. The results showed that the heat-treated smooth specimens with $SiO_2$ nano colloidal coating exhibited the highest bending strength at 0.0 wt% $SiO_2$ nano colloidal added, which is amounted to a 187 % increase over that of smooth specimen. Limiting temperature for bending strength of crack-healed zone for bending strength was about 1273 K. However, the bending strength of SSTS-3 and SSTS-4 was considerably increased while that of SSTS-1 and SSTS-2 was decreased at a temperature of 1,573K.

• Nano
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• 제13권12호
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• pp.1850146.1-1850146.9
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• 2018

The rapid development of smart textiles requires the large-scale fabrication of conductive fibers. In this study, we develop a simple, scalable and low-cost capillary-driven self-assembly method to prepare conductive fibers with uniform morphology, high conductivity and good mechanical strength. Fiber-shaped flexible and stretchable conductors are obtained by coating highly conductive and flexible silver nanowires (Ag NWs) on the surfaces of yarn and PDMS fibers through evaporation-induced flow and capillary-driven self-assembly, which is proven by the in situ optical microscopic observation. The density of Ag NWs and linear resistance of the conductive fibers could be regulated by tuning the assembly cycles. A linear resistance of $1.4{\Omega}/cm$ could be achieved for the Ag NWs-coated nylon, which increases only 8% after 200 bending cycle, demonstrating high flexibility and mechanical stability. The flexible and stretchable conductive fibers have great potential for the application in wearable devices.

• Journal of the Korean Wood Science and Technology
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• 제51권3호
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• pp.207-221
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• 2023

The increasing demand for clean energy requires considerable effort to find alternative energy sources, such as briquettes. This research aims to develop a charcoal briquette with added pine resin (API) that has excellent combustion speed and distinctive aroma. Briquettes are composed of charcoal, pine resin (concentration: 0%-30%), and starch (up to 7%). They are produced in several stages, including coconut shell pyrolysis in conventional combustion, to obtain charcoal for the briquette precursor. Briquette compaction is conducted by mixing and densifying the charcoal, pine resin, and starch using a hydraulic press for 3 min. The hydraulic press has a total surface area and diameter of 57.7 cm² and 3.5 cm, respectively. The briquettes are dried at different temperatures, reaching 70℃ for 24 h. The study results show that the briquettes have a thickness and diameter of up to 2 and 3.5 cm, respectively; moisture of 2.18%-2.62%; ash of 11.61%-13.98%; volatile matter of 27.15%-51.74%; and fixed carbon content of 40.24%-59.46%. The compressive strength of the briquettes is 186-540 kg/cm². Their calorific value is 5,338-6,120 kcal/kg, combusting at a high speed of 0.15-0.40 s. The methoxy naphthalene, phenol, benzopyrrole, and lauryl alcohol; ocimene, valencene, and cembrene are found in the API. The API briquette has several chemical compounds, such as musk ambrette, ocimene, sabinene, limonene, 1-(p-cumenyl) adamantane, butane, and propanal, which improve aroma, drug application, and fuel production. Accordingly, API briquettes have considerable potential as an alternative energy source and a health improvement product.

• Computers and Concrete
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• 제13권1호
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• pp.83-96
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• 2014

Accumulated annual reservoir sedimentation in Taiwan was 14.6 million m3 in 2010, seriously endangering reservoir safety and the water supply. In addition, the sintering temperature of reservoir-sediment aggregates (RSAs) is very high, and very energy consuming consequently. Therefore, to explore the effects of admixtures on sintering behavior and performance of the aggregates, two different admixtures are blended, waste-glass and municipal sewage sludge, into reservoir sediment to make artificial aggregates. Experimental results show that the lightweight characteristics of waste-glass/reservoir-sediment aggregates (WGRSAs) are more significant than those of sewage sludge/reservoir-sediment aggregates (SSRSAs). Moreover, as sintering temperature increases, the specific gravity of WGRSAs drops more apparently. The optimum sintering temperature of pure reservoir-sediment aggregates (PRSAs), SSRSAs, and WGRSAs was $1150^{\circ}C$, $1100^{\circ}C$, and $1050^{\circ}C$, respectively. The PRSAs are normal weight with better strength; the WGRSAs are lightweight and energy-saving; and the SSRSAs are lightweight with normal strength.

• 열처리공학회지
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• 제36권3호
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• pp.145-152
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• 2023

β titanium alloys containing β stabilizing elements such as V, Nb, Ta, Mo and Fe are widely used etc, due to their excellent specific strength, corrosion resistance, fatigue strength and easy formability. New metastable β titanium alloys are developed containing low-cost elements (Mo and Fe) in this study. Fe element is a strong β-stabilizer which can affect the mechanical and electrochemical properties of Ti-5Mo-xFe (x = 1, 4 wt%) alloys. These properties were analyzed in connection with microstructure and phase distribution. Ti-5Mo-4Fe alloy showed higher compression yield stress and maximum stress than Ti-5Mo-1Fe alloy due to solid-solution hardening and grain refinement hardening effect. As Fe element increased, Fe oxide formation and reduction of ${\bar{Bo}}$ (bond order) value affect the decrease of corrosion resistance. Ti-5Mo-xFe alloys were more excellent than Ti-6Al-4V ELI alloy.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.371-379
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• 2015

This paper represents the structural design of the light weight axle beam for medium duty commercial vehicle using hot press. To reduce the weight of the axle, axle beam of solid type was replaced by hollow type which was made by hot press. According to the change of axle beam structure and manufacturing method, we have to investigate the structural strength and fatigue performance. To verify the axle beam performance, the structural analysis was carried out by simplified axle beam model and various design parameters that are axle beam height, thickness and width. From the analysis results, the light weight axle beam structure was founded and applied the full model analysis. This study will be used as a guidance in development of the light weight axle for medium duty commercial vehicle.

• 한국정밀공학회지
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• 제31권6호
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• pp.513-519
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• 2014

For depth machining in die and mold, Electrical Discharge Machining (EDM) is used generally. To make deep hole and deep shape efficiently, cemented carbide endmill for depth machining is necessary. For this purpose, cemented carbide endmill was designed using design of experiment (DOE). To improve cutting performance, endmill was coated with multilayer surface treatment, TiAlCrSiN and TiAlCrN, for higher wear resistance. In order to evaluate the endmill, Transverse Rupture Strength (TRS) test was tried for investigating the relationship between surface treatment and strength in endmill body. Scratch test was also used for measuring adhesion force of each surface treatment. To evaluate hardness of surface treatment, Atomic Force Microscope (AFM) analysis was carried out. Wear test was executed for characteristics of each surface treatment in high temperature. Consequently, TiAlCrSiN was superior to the TiAlCrN coating in case of high temperature environment such as cutting.

• 기술혁신연구
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• 제18권1호
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• pp.199-218
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• 2010

정부는 지난 2008년 8월 새로운 국가 발전 패러다임으로 ‘저탄소 녹색성장’을 제안한 바 있다. 이 전략의 골자는 저탄소 사회의 구현과 새로운 성장동력을 동시에 확보한다는 것이다. 하지만 전통적으로 많은 학자들은 두 목적이 서로 상충되는 것으로 인식해 왔다. 다시 말해 녹색전략은 환경규제를 강화하게 되고 이것은 기업의 생산비용을 증대시키게 된다는 것이다. 그러나 포터를 비롯한 일단의 학자들은 이것을 근거가 부족하거나 지나치게 정태적인 분석의 결과로 보았다. 또 이들은 적절한 형태의 환경규제는 기술혁신을 유도함으로써 단기적 비용을 상쇄하는 효과를 나타낼 수 있다고 주장하였다. 이들 논쟁에 관해 많은 선행연구가 있지만 실증연구는 대단히 부족한 것이 사실이다. 본 논문은 환경관리를 위한 정부 정책과 기업의 혁신 활동이 어떤 여건에서 기업의 기술혁신을 유도할 수 있는지를 탐색하고자 하였다. 분석 결과, 기업의 녹색경영전략에 따라 경영성과에 차이가 있는 것으로 나타났다. 특히 외부 규제에 대한 대응정도나 내부 녹색경영 의지가 높을수록 기술성, 수익성, 성장성 등이 커지는 경향을 확인할 수 있었다. 그리고 국제 환경규제나 기후변화협약에 대해 기업이 처한 여건 역시 기술과 경영 두 측면에서 경영성과에 영향을 미치는 것으로 나타남으로써 기술혁신활동과 환경규제 그리고 경영성과 간의 상관성을 확인할 수 있었다.