• 소성∙가공
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• 제22권8호
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• pp.470-476
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• 2013

The aim of the current study was to predict shape recovery behavior of Ni-Ti shape memory alloy (SMA) wire after loading-unloading and after wire drawing. The superelasticity of SMA was analyzed by a hyper-elastic model for the Mullins effect using ABAQUS. Firstly, tensile tests and loading-unloading tests of the Ni-Ti SMA wire with a diameter 1.0 mm were performed using an MTS servo-hydraulic tester. The parameters for the Mullins effect were computed by ABAQUS based on curve-fitting of the loading-unloading test data. The proposed FE-model predicted the shape recovery of Ni-Ti SMA after wire drawing. Finally, the effectiveness of the model was verified by drawing experiments. The wire drawing experiments using the Ni-Ti SMA were conducted on a drawing machine(1ton, 50mm/s). In order to evaluate the shape recovery of Ni-Ti SMA, the drawn wires are annealed for 30min at $450^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1025-1027
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• 2009

Novel low temperature deposition process for nano-crystalline Si thin film is developed with the hyper-thermal neutral beam (HNB) technology. By our HNB assisted CVD system, the reactive particles can induce crystalline phase in Si thin films and effectively combine with heating effect on substrate. At low deposition temperature under $80^{\circ}C$, the HNB with proper incident energy controlled by the reflector bias can effectively enhance the nano-crystalline formation in Si thin film without any additional process. The electrical properties of Si thin films can be varied from a-Si to nc-Si according to change of HNB energy and substrate temperature. Characterization of these thin films with conductivity reveal that crystalline of Si thin film can increase by assist of HNB with appropriate energy during low temperature deposition. And low temperature prcoessed nc-Si TFT performance has on-off ratio as order 5.

• ETRI Journal
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• 제40권1호
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• pp.72-88
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• 2018

In the fifth generation (5G) era, the radio internet protocol capacity is expected to reach 20 Gb/s per sector, and ultralarge content traffic will travel across a faster wireless/wireline access network and packet core network. Moreover, the massive and mission-critical Internet of Things is the main differentiator of 5G services. These types of real-time and large-bandwidth-consuming services require a radio latency of less than 1 ms and an end-to-end latency of less than a few milliseconds. By distributing 5G core nodes closer to cell sites, the backhaul traffic volume and latency can be significantly reduced by having mobile devices download content immediately from a closer content server. In this paper, we propose a novel solution based on software-defined network and network function virtualization technologies in order to achieve agile management of 5G core network functionalities with a proof-of-concept implementation targeted for the PyeongChang Winter Olympics and describe the results of interoperability testing experiences between two core networks.

• 전기전자학회논문지
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• 제21권3호
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• pp.309-319
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• 2017

The research investigates the inhibition of fatty acid biosynthesis of the human Acetyl-CoA Carboxylase enzyme by the aromatic-structure inhibitors (also known as ligands) containing variables of substituents, contributing an important role in the treatment of fatty-acid metabolic syndrome expressed by the group of cardiovascular risk factors increasing the incidence of coronary heart disease and type-2 diabetes. The effective interoperability between ligand and enzyme is characterized by a 50% concentration of enzyme inhibitor ($IC_{50}$) which was determined by experiment, and the factor of geometry structure of the ligands which are modeled by quantum mechanical methods using HyperChem 8.0.10 and Gaussian 09W softwares, combining with the calculation of quantum chemical and chemico-physical structural parameters using HyperChem 8.0.10 and Padel Descriptor 2.21 softwares. The result data are processed with the combination of classical statistical methods and modern bioinformatics methods using the statistical softwares of Department of Pharmaceutical Technology - Jadavpur University - India and R v3.3.1 software in order to accomplish a model of the quantitative structure - activity relationship between aromatic-structure ligands inhibiting fatty acid biosynthesis of the human Acetyl-CoA Carboxylase.

• 한국전자통신학회논문지
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• 제7권1호
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• pp.91-96
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• 2012

최근 보안 문제와 관련한 연구가 많은 관심을 받고 있으며 비밀 통신과 암호 통신에 적용하기 위한 방법 중 하나로 하이퍼카오스 시스템과 이에 대한 동기화에 대한 연구가 활발하게 진행되고 있다. 본 논문에서는 SC-CNN으로 구성되는 하이퍼카오스 시스템의 동기화를 이루기 위한 방법으로 선형과 비선형 결합계수에 의한 동기화 기법을 제안하였다. 또한 컴퓨터 시뮬레이션을 이용하여 송신부의 서브시스템과 수신부의 서브시스템 사이에 동기화가 이루어지고, 전체 시스템의 송신부와 수신부 사이에 동기화가 이루어졌음을 위상 공간과 시계열데이터의 차를 통하여 확인하고 검증하였다. 검증 결과 거의 완전한 동기화가 이루어졌음을 확인할 수 있다.

• 한국정보처리학회논문지
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• 제6권9호
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• pp.2343-2349
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• 1999

최근에 개발되어 성공적으로 적용되고 있는 초기하분포 소프트웨어 신뢰성 성장 모델은 이 모델에서 중요한 역할을 하는 반응계수(sensitivity factor)를 추정 대상인 모수로 가정하고 있다. 본 논문은 먼저 디버깅과정의 무작위성을 반영하기 위해 반응계수를 이항분로를 하는 확률변수로 가정하여 초기하분포 신뢰성 성장 모델을 일반화한다. 이러한 일반화는 초기하분포 소프트웨어 신뢰성 성장 모델의 통계적 특성을 쉽게 파악할 수 있게 한다. 특히 일반화 된 모델의 모수를 최소자승법으로 추정하면 기존 모델에 최소자승법을 적용한 것과 같은 결과를 얻을 수 있음을 보이고, 더불어 최우추정치를 최소자승법으로 구하는 방법과 예측방법도 제시한다.

• 한국주조공학회지
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• 제20권2호
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• pp.89-96
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• 2000

The effects of modification processing on the refinement of primary Si and the wear behavior of hyper-eutectic Al-Si alloys have been mainly investigated. Refining effects of primary Si in Al-17%Si alloy was more efficient than that of B.390 alloy. Optimum condition of getting the finest primary Si microstructure was when AlCuP modifier is added into the melt at $750^{\circ}C$ and held it at $700^{\circ}C$ for 30 minutes. Wear loss in the specimens of as-cast condition decreases as the size of primary Si decreases, in the order of B.390 alloy, B.390 alloy with AlCuP addition, Al-17%Si alloy and Al-17%Si alloy with AlCuP addition. Wear loss in the aged condition of Al-17%Si alloy, B.390 alloy and B.390 alloy with AlCuP addition decreased due to the increase of compressive residual stress in the matrix by the aging treatment. While, wear loss increased in the aged specimens of Al-17%Si alloy with AlCuP addition and Hepworth addition in which compressive residual stress decreases by the aging treatment. Therefore, it is assumed that higher compressive residual stress in the matrix can reduce the wear loss in composite materials such as hyper-eutectic Al-Si alloys.

• 문화기술의 융합
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• 제4권4호
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• pp.343-348
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• 2018

안토시아닌 유도체는 다수의 식물에서 적색, 보라색 및 청색을 나타내는 천연 화합물의 중요한 성분이다. 안토시아닌 분자는 2-페닐 벤조피릴리움 염의 폴리메톡시 유도체이다. 안토시아닌의 유익한 특성에도 불구하고 다양한 질병을 예방하거나 치료하는 효과는 생체 이용률에 달려 있다. 따라서 이 연구에서는 안토시안 유도체의 전기적 특성을 알아보기 위해 HyperChem8.0의 PM3 방법을 이용하여 안토시아닌 유도체의 총 에너지, 밴드갭, 정전포텐셜, 알짜 전하량을 계산하여 유도체의 전기화학적 특성을 조사 하였다.

• 한국산업융합학회 논문집
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• 제25권3호
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• pp.467-476
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• 2022

The Bank of Korea raised the benchmark interest rate by a quarter percentage point to 1.75 percent per year, and analysts predict that South Korea's policy rate will reach 2.00 percent by the end of calendar year 2022. Furthermore, because market volatility has been significantly increased by a variety of factors, including rising rates, inflation, and market volatility, many investors have struggled to meet their financial objectives or deliver returns. Banks and financial institutions are attempting to provide Robo-Advisors to manage client portfolios without human intervention in this situation. In this regard, determining the best hyper-parameter combination is becoming increasingly important. This study compares some activation functions of the Deep Deterministic Policy Gradient(DDPG) and Twin-delayed Deep Deterministic Policy Gradient (TD3) Algorithms to choose a sequence of actions that maximizes long-term reward. The DDPG and TD3 outperformed its benchmark index, according to the results. One reason for this is that we need to understand the action probabilities in order to choose an action and receive a reward, which we then compare to the state value to determine an advantage. As interest in machine learning has grown and research into deep reinforcement learning has become more active, finding an optimal hyper-parameter combination for DDPG and TD3 has become increasingly important.

• 한국안전학회지
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• 제37권6호
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• pp.81-88
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• 2022

It is necessary to better understand the effect of age-related degradation on the performance of reinforced concrete shear walls in nuclear power plants in order to ensure their structural safety in the event of earthquakes. Therefore, this paper studies seismic fragility of the typical shear wall in nuclear power plants under earthquake excitation Reinforced concrete shear wall is composed of wall, horizontal and vertical flanges. Due to characteristics of its geometry, it is difficult to predict the ultimate behavior of shear wall under earthquake excitation. In this study, for more realistic numerical simulation, the Latin Hyper-Cube (LHC) simulation technique was used to generate uncertain variables for the material properties of concrete shear walls. The effects of crack, characteristics of inelastic behavior of concrete, and loss of cross section were considered in the nonlinear finite element analysis. The effects of aging-related deterioration were investigated on the performance of reinforced concrete shear walls through analysis of undegraded concrete shear walls and degraded concrete shear walls. The resulting seismic fragility curves present the change of performance of concrete shear wall due to age-related degradation.