• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.338-338
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• 2012

유기물을 이용하여 제작한 비휘발성 메모리 소자는 저전력으로 구동하고 공정이 간단할 뿐만아니라 구부림이 가능한 소자를 만들 수 있다는 장점 때문에 많은 연구가 진행되고 있다. 비록 다양한 유기물 나노 클러스터를 포함한 고분자 박막을 사용한 비휘발성 메모리 소자에 대한 연구가 많이 진행되었으나 [6,6]- phenyl-C85 butyric acid methyl ester (PCBM) 나노 클러스터가 고분자 박막에 분산되어 있는 메모리 소자의 휘어짐에 따른 전기적 특성의 변화에 대한 것은 연구되지 않았다. 본 연구에서는 스핀코팅 방법으로 PCBM 나노 클러스터가 polymethyl methacrylate (PMMA) 박막에 분산되어 있는 소자를 제작하여 휘어짐에 따른 전기적 특성의 변화에 대한 관찰을 수행하였다. 소자를 제작하기 위해서 PCBM 나노 클러스터와 PMMA를 클로로벤젠에 용해시킨 후에 초음파 교반기를 사용하여 PCBM 나노 클러스터와 PMMA가 고르게 섞인 용액을 형성하였다. 전극이 되는 Indium Tin Oxide (ITO) 유리기판 위에 PCBM 나노 클러스터와 PMMA가 섞인 용액을 스핀 코팅하고, 열을 가해 용매를 제거하여 PCBM 나노 클러스터가 PMMA에 분산되어 있는 박막을 형성하였다. PCBM 나노 클러스터가 분산된 PMMA 박막 위에 Al을 상부전극으로 열증착하여 메모리 소자를 완성하였다. 제작한 소자의 휘어짐에 따른 전기적 특성을 알아보기 위해서 10 mm 의 반지름을 갖는 휘어진 홀더를 제작 한 후에 소자를 구부리기 전과 후의 전류-전압 (I-V)을 각각 측정하였다. 또한 소자의 휘어짐에 따른 포획된 전하유지능력과 안정성을 알아보기 위해 $1{\times}105$번의 반복적인 읽기 전압을 가한 후 전기적 특성을 측정하였다. 실험 결과들을 토대로 메모리 소자의 휘어짐에 따른 전기적 특성 변화에 대해서 분석하고 그 원인에 대해서 규명하였다.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.63-69
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• 2015

The aim of this study was to investigate the deformation of packaging materials used for ready-to-eat (RTE) foods after the retort process and microwave heating. From the multilayer films consisting of polyethylene terephthalate (PET), polyamide (PA), and cast polypropylene (CPP) in a stand-up pouch form used for RTE foods, some deformation of the CPP layer, which was in direct contact with the food, was observed after the retort process and microwave heating. The damage was more severely caused by microwave heating than by the retort process. This may be attributed to diverse factors including the non-uniform heating in a microwave oven, the sorption of oil into the packaging film, and the different characteristics of food components such as viscosity, salt and water content. The development of heat-resistant packaging materials and systems suitable for microwave heating of RTE foods is required for the safety of consumers.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.741-744
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• 2008

Quality control of early age concrete significantly influences the long term performance. Primary factors for early age concrete quality control should include the relative humidity and temperature variation, and these are more important as structures become massive and huge. Temperature raise due to cement hydration causes stress, which can develop to cracking with internal and/or external restraints. Exposure conditions including ambient temperature, humidity and wind also significantly affect the cracking behavior of early age concrete. Among many of studies on the early age concrete behavior, investigation on the variation of temperature and relative humidity internal of concrete is not common. That is in part because the difficulties in measuring the relative humidity and temperature inside the concrete. This study used a digital sensor with an appropriate logger to measure internal temperature and relative humidity. This direct measuring method is expected to provide more reliable and comprehensive data acquisition on the early age behavior of concrete.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.4
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• pp.245-253
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• 2016

The friction and deformation of a tire causes heat generation, which causes a temperature rise of the tire. This temperature rise can be a source of tire damage. The object of this study is to investigate the cooling effect of the application of a fin to the tire side to suppress the temperature rise. Eight different fin shapes were considered, and the sidewall surface temperature reduction owing to the cooling fin shape was numerically analyzed. In addition, the flow characteristics and heat transfer characteristics of the vortex of the pin rear were compared.

• Fire Science and Engineering
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• v.24 no.3
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• pp.39-44
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• 2010

The cone calorimeter method which is currently used to measure the heat release rate has a fixed rate of radiation. However, in the real fire, when flame combustible material burns, it releases the identical heat flux. We measured the changes of temperature of a fire using FDS in order to analyze flexible heat flux of combustion characteristics. In this study, the rate of radiation of cone calorimeter was adopted by using FDS. Follow those results, it produce between the rate of radiation in the growth period and decline period have a significant impact on heat release rate of PMMA.

• Journal of the Mineralogical Society of Korea
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• v.7 no.2
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• pp.97-110
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• 1994

고사리광산의 도석에는 다량의 석영과 함께 녹니석/스멕타이트 혼합층광물, 운도/스멕타이트 혼합층광물, 카오리나이트와 같은 점토광물이 산출한다. 이들 점토광물에 대해 주로 X-선회전분석과 화학분석 등을 이용하여 광물학적 특성을 검토하였다. 이 광산의 도석은 녹니석/스멕타이트 혼합층광물을 다량 함유하는 것이 특징으로 나타났다. 이 녹니석/스멕타이트 혼합층광물은 Li을 함유하는 돈바싸이트로 된 녹니석층과 바이델라이트에 가까운 스apr타이트층으로 구성된 혼합층구조를 이룬다. 이 곳에 산출하는 운모/스멕타이트 혼합층광물은 모두 약 15% 이하의 팽윤층을 포함하는 것으로 되어 있다.이 광산의 도석은 백악기의 유문암 및 유문암질 응회암이 열수변질작용을 받아 형성된 것으로 나타났다. 점토광물조합의 분포상태에 의해 대략적인 변질분대가 나누어진다. 중심부인 강변질대에서는 다량의 녹니석/스텍타이트 혼합층광물이 나타나며 카오리나이트가 수받되기도 한다. 그 외곽지역의 약변질대에서는 점토광물로서 운모/스멕타이트 혼합층광물이 주로 나타난다. 카오리나이트는 주로 열극이나 그 주위에 국부적으로 산출되는 경향이 있다. 이와 같은 변질광물의 산출상태로 볼 때 변질작용의 진행에 따라 운모/스멕타이트 혼합층광물이 먼저 형성된 후 이것의 일부가 녹니석/스맥타이트 혼합층광물 및 카오리나이트로 변화된 것으로 생각된다. 도 카오리나이트는 열수의 공급이 많은 열극부에서 녹니석/스멕타이트 혼합층 광물과 거의 동시기에 침전된 것으로 생각된다. 이 광산에서 산출하는 일부 운모/스멕타이트 혼합층광물은 후기의 변질작용에 의해 형성된 것도 포함된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.1-6
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• 2019

The objective of this study was to investigate performance characteristics of thermal management system(TMS) in a fuel cell electric vehicle with 100kW Fuel Cell(FC) system. In order to build up analytic modelling for TMS, each component was installed and tested under various operating conditions, such as water pump, radiator, 3-Way valve, COD heater, and FC stack etc. and as the results of them, correlations reflecting component's characteristics with flow rate, air velocity were developed. Developed analytic modelling was carried out under various operating conditions on the road. To verify modelling's accuracy, after prediction for optimum coolant flow rate was fulfilled under certain operating conditions, such as FC system, water pump speed, opening of 3-way valve, and pipe resistance, analytic and experimental values were compared and good agreement was shown. In order to predict cold-start operating performance for analytic modelling, coolant temperature variation was analyzed with $-20^{\circ}C$ ambient temperature and duration was predicted to rise in optimum temperature for FC. Because there is appropriate temperature difference between inlet and outlet of FC stack to operate FC system properly, related analysis was performed with respect to power consumption for TMS and heat rejection rate and performance map was depicted along with FC operating conditions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.1
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• pp.1-12
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• 2023

It is very time-intensive to obtain data with labels on anomaly detection tasks for multivariate time series. Therefore, several studies have been conducted on unsupervised learning that does not require any labels. However, a well-done integrative survey has not been conducted on in-depth discussion of learning architecture and property for multivariate time series anomaly detection. This study aims to explore the characteristic of well-known architectures in anomaly detection of multivariate time series. Additionally, architecture was categorized by using top-down and bottom-up approaches. In order toconsider real-world anomaly detection situation, we trained models with dataset such as power grids or Cyber Physical Systems that contains realistic anomalies. From experimental results, we compared and analyzed the comprehensive performance of each architecture. Quantitative performance were measured using precision, recall, and F1 scores.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.241-247
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• 2021

This study analyzed the changes in explanatory power of the modified Jones model(1995) for estimating the amount of accruals for Korean Stock Market listed companies from 1990 to 2019. We hypothesized that if the properties of financial variables used in the existing model change over time or change in discretionary ratios, the model's explanatory power will change. As the result of regression models, I found that the explanatory power of the modified Jones model(1995) gradually declined over time. The results may be derived from the increase in accruals itself and the changes in the distribution of variables contained in the model. The results of this research's chronological approach are expected to give important implications to both academic researchers and accounting information users.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.1
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• pp.1-11
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• 2018

In this study, pro-oxidant($d2w^{(R)}$) and rPP/ZnO nanocomposite flexible films for food packaging were prepared, and their mechanical and antimicrobial properties were investigated. As a result, the carbonyl index and hydroxyl index increased with exposured time to heat and UV rays. Surface analysis showed that the addition of zinc oxide improved the dispersibility and compatibility of the polymer, so that the surface of the composite film was smooth and the zinc oxide particles were smaller than the compared film. And it kept the physical properties by heat and UV ray blocking effect, and it worked to reduce decomposition. In the antimicrobial activity test, the microbial reduction rate was 3 logs or more at the use concentration of zinc oxide. The tensile strength was increased and the elongation was decreased. Oxidative degradability of multi-layered film in UV exposured for 72 hours, the molecular weight of the film decreased by 75.6%, 1,294 g/mol Mn and 5,920 g/mol Mw. In the safety analysis of food packaging materials, we obtained that are in standard of polypropylene, a food contact material of domestic law.