• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.149-150
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• 2007

ONO(Oxide-Nitride-Oxide)구조는 기억소자의 전하보유 능력을 향상시키기 위해 도입된 게이트 절연막이다. 본 연구에서는 ELA(Excimer Laser Annealing)방법으로 비정질 실리콘을 결정화 시켜서 그 위에 NVM(Nonvolatile Memory)소자를 만들어 전기적 특성을 측정하여 결과를 나타내었다. 실험 결과 같은 크기의 $V_D$에서 $V_G$를 조절함으로써 $I_D$의 크기를 조절할 수 있었다. $V_G-I_D$ Graph에서는 $I_{on}$과 $I_{off}$, 그리고 Threshold Voltage를 알 수 있었다. $I_{on}/I_{off}$ Ratio는 $10^3-10^4$이다. $V_G-I_D$ Graph에서는 게이트에 인가하는 Bias의 양을 통해서 Threshold Voltage의 크기를 조절할 수 있었다. 이는 Trap되는 Charge의 양을 임의로 조절할 수 있다는 것을 의미하며, 이러한 Programming과 Erasing의 특성을 이용하여 기억소자로서의 역할을 수행하게 된다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.154-164
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• 2019

A rotor dynamic analysis is mandatory for stability and design optimization of submerged propellers and turbines. An accurate simulation requires a proper consideration of fluid-induced reaction forces. This paper presents a bi-directional coupling of a bond graph method solver and an unsteady vortex lattice method solver where the former is used to model the rotor dynamics of the power train and the latter is used to predict transient hydrodynamic forces. Due to solver coupling, determination of hydrodynamic coefficients is obsolete and added mass effects are considered automatically. Additionally, power grid and structural faults like grid fluctuations, eccentricity or failure could be investigated using the same model. In this research work a fast, time resolved dynamic simulation of the complete power train is conducted. As an example, the rotor dynamics of a tidal stream turbine is investigated under two inflow conditions: I - shear flow, II - shear flow + water waves.

• 한국자원식물학회지
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• 제28권4호
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• pp.400-410
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• 2015

Juniperus chinensis (Cupressaceae) is a valuable woody plant resource, but this rare plant is only distributed in restricted regions in Korea. In this study, we surveyed the geographic distribution regions, variation of sex ratio and the dynamics of natural populations of J. chinensis. in order to establish conservation strategies for the sustainable conservation of this important resource tree. The 17 natural populations of J. chinensis are restrictively distributed in the shore cliffs of (1) Ulleungdo island, (2) Gyeongju-si to Gangneung-si of the eastern coast, the riverside cliff along (3) Donggang-river of Jungsun-gun and Pyeongchang-gun and (4) branch of Nakdonggang-river in Uiseong-gun. The populations in Ulleungdo island showed continuous population distribution of over 200 individuals, but populations in other regions had discontinuous population distribution of under 200. The population of J. chinensis surveyed in Korea was estimated in ca. 3,200 individuals. The sex ratio (male/female) among populations of J. chinensis was diverse with variation from 0.46~1.67 range, but showed no significance. The sex ratio of the total individuals by species level was 0.74, and the percentage of female tree was significantly higher than the male. The results of dynamics analysis within population among regions showed that seedlings and saplings of J. chinensis in three regions surveyed were continuously regenerating. The distribution of DBH class showed a stable population structure of inverse J shape graph, but fragmentation and decrease in populations because of invading broad-leaved shrubs and trees from the surroundings were concerned. Further studies, and in situ and ex situ conservation strategies for the sustainable conservation on natural populations of this rare resources woody plant, J. chinensis in Korea are recommended.

• 대한수학회지
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• 제48권1호
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• pp.105-115
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• 2011

Let f be a function which assigns a positive integer f(v) to each vertex v $\in$ V (G), let r, s and t be non-negative integers. An f-coloring of G is an edge-coloring of G such that each vertex v $\in$ V (G) has at most f(v) incident edges colored with the same color. The minimum number of colors needed to f-color G is called the f-chromatic index of G and denoted by ${\chi}'_f$(G). An [r, s, t; f]-coloring of a graph G is a mapping c from V(G) $\bigcup$ E(G) to the color set C = {0, 1, $\ldots$; k - 1} such that |c($v_i$) - c($v_j$ )| $\geq$ r for every two adjacent vertices $v_i$ and $v_j$, |c($e_i$ - c($e_j$)| $\geq$ s and ${\alpha}(v_i)$ $\leq$ f($v_i$) for all $v_i$ $\in$ V (G), ${\alpha}$ $\in$ C where ${\alpha}(v_i)$ denotes the number of ${\alpha}$-edges incident with the vertex $v_i$ and $e_i$, $e_j$ are edges which are incident with $v_i$ but colored with different colors, |c($e_i$)-c($v_j$)| $\geq$ t for all pairs of incident vertices and edges. The minimum k such that G has an [r, s, t; f]-coloring with k colors is defined as the [r, s, t; f]-chromatic number and denoted by ${\chi}_{r,s,t;f}$ (G). In this paper, we present some general bounds for [r, s, t; f]-coloring firstly. After that, we obtain some important properties under the restriction min{r, s, t} = 0 or min{r, s, t} = 1. Finally, we present some problems for further research.

• 한국응용곤충학회지
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• 제44권4호
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• pp.271-276
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• 2005

복숭아혹진딧물의 섭식행동을 관찰하기 위해, 고추, 무, 배추, 가지, 참외 등 5종류의 기주식물에서 EPG기술을 이용하였다. 복숭아혹진딧물의 구침이 식물체 표면에 접촉된 후 전기적 연결이 일어나기까지 소요되는 시간과 맨 처음 potential drop이 일어나기까지 소요된 시간, 구침의 세포간극내에서의 활동에 의하여 일어나는 potential drop의 수, 전기적 연결신호가 나타난 시점부터 체관부를 섭식하는 순간까지 소요된 시간 등을 조사한 결과 Potential drop 수에서는 기주들 사이에 유의성 있는 차이를 나타내었다. 그러나 나머지 요인에서는 기주식물들 사이에 큰 차이를 보이지 않았지만, 참외나 배추보다는 고추, 무, 가지에서 즘 더 기주선호성과 관련된 섭식패턴들을 확인할 수 있었다.

• Genomics & Informatics
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• 제7권3호
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• pp.171-174
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• 2009

The characteristics of metabolic pathways make them particularly amenable to layered graph drawing methods. This paper presents a visual Java-based tool for drawing and annotating biological pathways in two- and a-half dimensions (2.5D) as an alternative to three-dimensional (3D) visualizations. Such visualization allows user to display different groups of clustered nodes, in different parallel planes, and to see a detailed view of a group of objects in focus and its place in the context of the whole system. This tool is an extended version of J2dPathway.

• 전자통신동향분석
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• 제36권3호
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• pp.106-118
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• 2021

The field of brain science (or neuroscience in a broader sense) has inspired researchers in artificial intelligence (AI) for a long time. The outcomes of neuroscience such as Hebb's rule had profound effects on the early AI models, and the models have developed to become the current state-of-the-art artificial neural networks. However, the recent progress in AI led by deep learning architectures is mainly due to elaborate mathematical methods and the rapid growth of computing power rather than neuroscientific inspiration. Meanwhile, major limitations such as opacity, lack of common sense, narrowness, and brittleness have not been thoroughly resolved. To address those problems, many AI researchers turn their attention to neuroscience to get insights and inspirations again. Biologically plausible neural networks, spiking neural networks, and connectome-based networks exemplify such neuroscience-inspired approaches. In addition, the more recent field of brain network analysis is unveiling complex brain mechanisms by handling the brain as dynamic graph models. We argue that the progress toward the human-level AI, which is the goal of AI, can be accelerated by leveraging the novel findings of the human brain network.

• 대한화학회지
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• 제39권4호
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• pp.252-256
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• 1995

고순도 구리 금속중에 존재하는 미량의 안티몬을 사전 분리시키지 않고 직접 분석할 수 있는 GFAAS 조건을 조사하였다. 과량 존재하는 구리가 안티몬의 감도를 향상시키는 matrix modifier의 역할을 하고 있음을 알았다. 희화 온도는 $600^{\circ}C(20s){\sim}700^{\circ}C(10s)$를 이용할 때에 $1000^{\circ}C(20s){\sim}1100^{\circ}C(10s)$보다 감도가 향상되며, 원자화 온도는 $2200^{\circ}C$에서 가장 좋은 Sb의 흡광도를 보였다. Ar 기체의 압력은 $2.0\; kg/cm^2$일때에 최적임을 확인하였으며, 20 ppb에서 200 ppb Sb 범위에서 변화율(coefficient of variation)이 5% 미만이며 직선 관계를 보였다.

• 제어로봇시스템학회논문지
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• 제19권5호
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• pp.457-461
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• 2013

This paper proposes an image feature-based real-time RGB-D (Red-Green-Blue Depth) 3D SLAM (Simultaneous Localization and Mapping) system. RGB-D data from Kinect style sensors contain a 2D image and per-pixel depth information. 6-DOF (Degree-of-Freedom) visual odometry is obtained through the 3D-RANSAC (RANdom SAmple Consensus) algorithm with 2D image features and depth data. For speed up extraction of features, parallel computation is performed with GPU acceleration. After a feature manager detects a loop closure, a graph-based SLAM algorithm optimizes trajectory of the sensor and builds a 3D point cloud based map.

• 제어로봇시스템학회논문지
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• 제21권6호
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• pp.565-570
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• 2015

Supervised machine learning has become popular in discovering context descriptions from sensor data. However, collecting a large amount of labeled training data in order to guarantee good performance requires a great deal of expense and time. For this reason, semi-supervised learning has recently been developed due to its superior performance despite using only a small number of labeled data. In the existing semi-supervised learning algorithms, unlabeled data are used to build a graph Laplacian in order to represent an intrinsic data geometry. In this paper, we represent the unlabeled data as the spatial-temporal dataset by considering smoothly moving objects over time and space. The developed algorithm is evaluated for position estimation of a smartphone-based robot. In comparison with other state-of-art semi-supervised learning, our algorithm performs more accurate location estimates.