• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.470-473
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• 2007

Wireless Sensor Networks (WSNs) have merged to become one of the most promising applications of wireless ad hoc networks. A defer timer has been used in some of existing network protocols to solve a set of problems in WSNs. We first investigate the use of a defer timer to fully take the advantage of it in WSNs. We demonstrate that by properly setting up the defer timers, many difficult issues in sensor networks, such as power limitation, the broadcast storm problem, and the construction of the virtual backbone, can be easily tackled with only the help of simple localized information at each node. In this paper, we present the power of a defer timer in the design of dominating set construction protocol for broadcasting. The ns 2 computer simulations are carried out for performance study.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.137-140
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• 2002

This paper describes the effect of distributed generations (DG) on the bus protection scheme. When the generating capacity of DG is larger than 3 MVA totally, DG are generally connected to the 22.9 kV bus directly with the dedicated line. Due to the fault current contribution of DG, the overcurrent protective relay that have conventional set value cannot detect the fault occurred in distribution power network with DG. Therefore. the impacts from interconnection of DG on the overcurrent protective relay for bus protection should be accurately assessed and mitigated. Simulation results show that it would be necessary to modify the overcurrent protective relay set value for protecting the bus according to the generating capacity of DG.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.2
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• pp.159-168
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• 2010

This paper presents a mathematical model and simulation method for investigating the performance of set net systems and fish cage systems influenced by currents and waves. Both systems consist of netting, mooring ropes, a floating collar and sinkers. The netting and ropes were considered flexible structures and the floating collar was considered an elastic structure. Both were modeled on a mass-spring model. The structures were divided into finite elements and mass points were placed at the mid-point of each element, and the mass points were connected by mass-less springs. Each mass point was subjected to external and internal forces and the total force was calculated at every integration step. An implicit integration scheme was used to solve the nonlinear dynamic system. The computation method was applied to dynamic simulation of actual systems simultaneously influenced by currents and waves in order to evaluate their practicality. The simulation results improved our understanding of the behavior of the structure and provided valuable information concerning the optimized design of set net and fish cage systems exposed to an open ocean environment.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.411-418
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• 2001

This paper describes the design and implementation of a home network management system through a web browser. All digital devices are connected to a set-top box on which personal java environment is installed through an IEEE1394 serial bus. The embedded web server on the set-top box supports persistent-connection of HTTP1.1 and servlet engine for JSDK2.1. The home network management system is developed as the form of a servlet and uses JNI to access IEEE1394 device driver\`s APIs. When a client selects an icon related with a device the user interface applet of the device is downloaded into a client\`s web browser and communicates with a related servlet through TCP/IP APIs.

• Bulletin of the Korean Mathematical Society
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• v.58 no.5
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• pp.1279-1300
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• 2021

Let P be a finite point set in ℝ² with the set of distance n-chains defined as ∆_n(P) = {(|p₁ - p₂|, |p₂ - p₃|, …, |p_n - p_n+1|) : p_i ∈ P}. We show that for 2 ⩽ n = O_|P|(1) we have ${\mid}{\Delta}_n(P){\mid}{\gtrsim}{\frac{{\mid}P{\mid}^n}{{\log}^{\frac{13}{2}(n-1)}{\mid}P{\mid}}}$. Our argument uses the energy construction of Elekes and a general version of Rudnev's rich-line bound implicit in [28], which allows one to iterate efficiently on intersecting nested subsets of Guth-Katz lines. Let G is a simple connected graph on m = O(1) vertices with m ⩾ 2. Define the graph-distance set ∆_G(P) as ∆_G(P) = {(|p_i - p_j|)_{i,j}∈E(G) : p_i, p_j ∈ P}. Combining with results of Guth and Katz [17] and Rudnev [28] with the above, if G has a Hamiltonian path we have ${\mid}{\Delta}_G(P){\mid}{\gtrsim}{\frac{{\mid}P{\mid}^{m-1}}{\text{polylog}{\mid}P{\mid}}}$.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.1
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• pp.63-70
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• 2018

The foreign concession of Yokohama was the first downtown formed through the open port of Yokohama. It became a stepping stone to the center of the market economy. Yokohama was regarded as the turning point of modernization in Japanese history and it reached the high light of modern city in Japan. In the nineteenth century the term "open port" which occurred in East Asia was directly connected with modernization. Nevertheless, there is not many researches on architectural history about the central space of the open port city. As the method of research, we examine the parcels and spatial changes that are based on the contents of maps and pictures in terms of architectural history. For the foreign concession that was set up in Yokohama and the first open port in Japan, the spatial scope was set for certain and the temporal range was also set from the setting of the concession in 1859 to the abolition in 1899. The purpose of this study is to consider the future research related to the study of the open port city from the perspective of comparative historical research.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.2043-2052
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• 1994

This paper proposes a new parallel ASIC architecture for real-time image processing to reduce inter-processing element (inter-PE) communication overhead, called a Sliding Memory Plane (SliM) Image Processor. The Slim Image Processor consists of $3\times3$ processing elements (PEs) connected by a mesh topology. With easy scalability due to the topology. a set of SliM Image Processors can form a mesh-connected SIMD parallel architecture. called the SliM Array Processor. The idea of sliding means that all pixels are slided into all neighboring PEs without interrupting PEs and without a coprocessor or a DMA controller. Since the inter-PE communication and computation occur simultaneously. the inter-PE communication overhead, significant disadvantage of existing machines greatly diminishes. Two I/O planes provide a buffering capability and reduce the date I/O overhead. In addition, using the by-passing path provides eight-way connectivity even with four links. with these salient features. SliM shows a significant performance improvement. This paper presents architectures of a PE and the SliM Image Processor, and describes the design of an instruction set.

• Journal of Broadcast Engineering
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• v.22 no.2
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• pp.162-172
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• 2017

In this paper, we propose facial expression recognition using CNN (Convolutional Neural Network), one of the deep learning technologies. To overcome the disadvantages of existing facial expression databases, various databases are used. In the proposed technique, we construct six facial expression data sets such as 'expressionless', 'happiness', 'sadness', 'angry', 'surprise', and 'disgust'. Pre-processing and data augmentation techniques are also applied to improve efficient learning and classification performance. In the existing CNN structure, the optimal CNN structure that best expresses the features of six facial expressions is found by adjusting the number of feature maps of the convolutional layer and the number of fully-connected layer nodes. Experimental results show that the proposed scheme achieves the highest classification performance of 96.88% while it takes the least time to pass through the CNN structure compared to other models.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.116-121
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• 2005

To realize the tap coefficient of a finite impulse response(FIR) filter or the twiddle factor of a fast Fourier transform(FFT) using a current-mode analog circuit, a high accurate current-attenuator circuit is needed This paper introduces an accuracy enhancement technique in the current-mode signal processing. First of all, the DC of set-current error in a conventional current-attenuator using a gate-ratioed orient mirror circuit is analyzed and then, the current-attenuator circuit with a negligibly small DC offset-current error is introduced. The circuit consists of N-output current mirrors connected in parallel with me another. The output current of the circuit is attenuated to 1/N of the input current. On the basis of the Kirchhoff current law, the current scale ratio is determined simply by the number of the current mirrors in the N-current mirrors connected in parallel. In the proposed current-attenuator circuit the scale accuracy is limited by the ac gain error of the current mirror. Considering that a current mirror has a negligibly small ac gain error, the attainable maximum scale accuracy is theoretically -80[dB] to the input current.

• Kyungpook Mathematical Journal
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• v.56 no.2
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• pp.349-355
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• 2016

For any integer $n{\geq}2$, each palindrome of n induces a circulant graph of order n. It is known that for each integer $n{\geq}2$, there is a one-to-one correspondence between the set of (resp. aperiodic) palindromes of n and the set of (resp. connected) circulant graphs of order n (cf. [2]). This bijection gives a one-to-one correspondence of the palindromes ${\sigma}$ with $gcd({\sigma})=1$ to the connected circulant graphs. It was also shown that the number of palindromes ${\sigma}$ of n with $gcd({\sigma})=1$ is the same number of aperiodic palindromes of n. Let $a_n$ (resp. $b_n$) be the number of aperiodic palindromes ${\sigma}$ of n with $gcd({\sigma})=1$ (resp. $gcd({\sigma}){\neq}1$). Let $c_n$ (resp. $d_n$) be the number of periodic palindromes ${\sigma}$ of n with $gcd({\sigma})=1$ (resp. $gcd({\sigma}){\neq}1$). In this paper, we calculate the numbers $a_n$, $b_n$, $c_n$, $d_n$ in two ways. In Theorem 2.3, we $n_d$ recurrence relations for $a_n$, $b_n$, $c_n$, $d_n$ in terms of $a_d$ for $d{\mid}n$ and $d{\neq}n$. Afterwards, we nd formulae for $a_n$, $b_n$, $c_n$, $d_n$ explicitly in Theorem 2.5.