• The Korean Journal of Archival Studies
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• no.35
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• pp.133-160
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• 2013

As the network and electronic devices have been developed rapidly, the influences the web exerts on our daily lives have been increasing. Information created on the web has been playing more and more essential role as the important records which reflect each era. So there is a strong demand to archive information on the web by a standardized method. One of the methods is the snapshot strategy, which is crawling the web contents periodically using automatic software. But there are two problems in this strategy. First, it can harvest the same and duplicate contents and it is also possible that meaningless and useless contents can be crawled due to complex IT skills implemented on the web. In this paper, we will categorize the problems which can emerge when crawling web contents using snapshot strategy and present the possible solutions to settle the problems through the technical aspects by crawling the web contents in the public institutions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.247-252
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• 2019

The diffraction properties of optical signals by multi-layered periodic structures is formulated in two-dimensional space by using Fourier expansions associated with basic grating profile. The fields in each layer are then expressed in terms of characteristic modes, and the complete solution is found rigorously by using a modal transmission-line theory(MTLT) to address the pertinent boundary-value problems. Such an approach can treat periodic arbitrary gratings containing arbitrarily shaped dielectric components, which may generally have optical properties along directions that are parallel or perpendicular to the multi-layers. This paper illustrates the present approach by comparing our numerical results with data reported in the past for simple periodic circular 2D structures. In addition, this proposed theory can apply easily for more complex configurations, which include multiple periodic regions with several possible canonic shapes and high dielectric constants.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.2
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• pp.439-446
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• 2019

In this paper, we propose a encryption method using C-MLCA and 1D CAT to secure medical image for efficiently. First, we generate a state transition matrix using a Wolfram rule and create a sequence of maximum length. By operating the complemented vector, it converts an existing sequence to a more complex sequence. Then, we multiply the two sequences by rows and columns to generate C-MLCA basis images of the original image size and go through a XOR operation. Finally, we will get the encrypted image to operate the 1D CAT basis function created by setting the gateway values and the image which is calculated by transform coefficients. By comparing the encrypted image with the original image, we evaluate to analyze the histogram and PSNR. Also, by analyzing NPCR and key space, we confirmed that the proposed encryption method has a high level of stability and security.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.2
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• pp.142-149
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• 2019

The coils to transmit the electric energy are necessary to charge an electric vehicle wirelessly. There are several types of coils, from basic circular coils to DD-type coils for enhancing the coupling effect between two coils. However, DD-type coils with a good coupling effect between coils have a disadvantage in use because of the structure complexity of the power conversion device of transmitting and receiving side. In this paper, we propose a method to calculate the inductance value and to design the size of the spiral inductor which is convenient to fabricate when the power is transmitted wirelessly by using two coils in free space. Since the bifurcation phenomenon occurs when the XLm value is similar to the load resistance value in the resonator the XLm value was selected to be equal to the minimum load resistance value to minimize this phenomenon, and the inductance value required for the resonator was calculated. In order to realize the calculated inductance value by the spiral inductor, the relationship between the inductance value and the size, the number of turns, the total coil length of a spiral inductor was investigated. In addition, the change of coupling coefficient k according to the horizontal separation of two coils was examined and an appropriate inductor was selected.

• Convergence Security Journal
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• v.21 no.2
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• pp.47-56
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• 2021

Network topology visualization has been studied a lot since the past and developed with many tools. The network topology has strength in understanding the overall structure of a network physically and is useful for understanding data flow between nodes logically. Although there are existing tools, not many can be utilized efficiently while using the general network node data structure and express the topology similar to the actual network structure. In this paper, we propose an efficient method to visualize topology using only connection information of network nodes. The method finds the central node by using the centrality, the influence of nodes in the network, and visualizes the topology by dynamically segmenting all nodes and placing network nodes in 3D space using the weight of the child node. It is a straightforward method, yet it effectively visualizes in the form of an actual network structure.

• Smart Media Journal
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• v.10 no.2
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• pp.110-118
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• 2021

The Internet of Things (IoT) technology, a key growth engine of the 4th industrial revolution, has grown to a stage where it can autonomously communicate with each other and process data according to space and circumstances. Accordingly, the IT infrastructure becomes increasingly complex and the importance of the monitoring field for maintaining the system stably is increasing. Monitoring technology has been used in the past, but there is a need to find a flexible monitoring system that can respond to the rapidly changing ICT technology. This paper conducts research on designing and testing an open source-based Prometheus monitoring system. We builds a simple infrastructure based on IoT devices and collects data about devices through the Exporter. Prometheus collects data based on pull and then integrates into one dashboard using Grafana and visualizes data to monitor device information.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.264-264
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• 2015

최근 기후변화는 우리 삶에 다양한 영향을 미치고 있으며, 이에 따른 수문순환 변화 역시 자명하게 받아들이고 있다. 이에 따라 수자원 취약성 평가 및 대책에 관한 연구는 다양하게 진행되고 있는 실정이다. 하지만 국내의 경우 전체 유역에 대한 수자원 취약성 평가 연구는 부족한 실정이다. 따라서 본 연구에서는 국내 총 12 수계인 한강, 안성천, 금강, 삽교천, 영산강, 섬진강, 탐진강, 만경강, 동진강, 낙동강, 태화강, 형산강 유역에 대한 수자원 취약성 평가를 실시하였다. 평가 방법으로는 장기간에 걸친 다양한 토양의 특징, 토지이용, 관리상태의 변화에 따른 크고 복잡한 유역의 유출량을 추정하기 위해 개발된 SWAT(Soil and Water Assessment Tool) 모형을 이용하여 수문 모형을 구축하였고, 유출 관련 매개변수 최적화 작업은 SWAT-CUP 모형을 이용하였다. 최적화된 매개변수의 적용을 통해 각 유역별 유출량을 산정하였다. 그 결과 2009년과 2011년은 한강, 낙동강, 금강, 영산강순 이였으며, 2010년은 낙동강, 한강, 금강, 영산강순 이였다. 면적별 유출량인 비유량(specific discharge)을 산정한 결과, 2009년에는 영산강, 낙동강, 금강, 한강순 이며, 2010년에는 영산강, 금강, 낙동강, 한강순 이였으며, 2011년에는 금강, 한강, 영산강, 낙동강 순을 보였다. 또한, 인구당 유출량 산정 결과 2009년에는 영산강, 금강, 낙동강, 한강순 이며, 2010년에는 영산강, 금강, 낙동강, 한강순 이며, 2011년에는 영산강, 금강, 낙동강, 한강순 이었다. 이를 바탕으로 국내 총 12 수계에 대한 수자원 취약성을 산정해보았다. 대응변수는 이수의 수요 및 공급적인 측면에서 구분하였으며, 사회/경제, 물 이용, 환경, SWAT으로 구성하였습니다. 수자원 취약성 평가를 위해 다기준의사결정기법(MCDM, Multi-Criteria Decision Making) 중 하나인 TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution)기법을 사용하였다. 산정 결과 삽교천, 동진강, 형산강, 안성천, 섬진강, 만경강, 낙동강, 영산강, 태화강, 금강, 한강, 탐진강 순 이였다. 본 연구 결과는 향후 다중 공간에 구축한 고해상도 모형을 통해 국내 수문상황 진단 및 고해상도 미래 수문 시나리오 생산을 통한 수자원 관리에도 활용될 전망이며, 기후변화 취약성 평가를 위한 지표 개발에 이용될 예정이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.405-405
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• 2019

최근 기후변화 및 지구온난화의 영향으로 집중호우, 돌발홍수, 가뭄 등 기상 이변이 빈번하게 발생하고 있어 물관리의 불확실성과 복잡성이 매우 높아지고 있다. 대규모 하천의 경우 다목적댐과 다기능보를 이용하여 홍수 및 가뭄에 대응이 비교적 용이하나, 중소하천의 경우 하천길이가 짧고 하천경사가 급해서 홍수파의 이동시간이 짧기 때문에 홍수대비를 위한 시간이 매우 짧다. 또한 중소하천 관리를 담당하는 지자체는 열악한 재정 여건과 전문인력 및 기술력 부족으로 인해 예방보다 사후복구에 집중하는 상황이며, 최근 하천 고수부지를 수변공원, 천변주차장 등으로의 공간적 활용이 증가됨에 따라 홍수발생시 위험성도 증가하고 있어 예방 및 대응 중심의 홍수 모니터링 기준 수립이 시급하다. 이에 K-water는 공익사업의 일환으로 K-water의 홍수 및 하천관리 노하우를 지자체와 공유하고 있다. 해당지자체의 과거 기상 및 수문자료들을 활용하여 홍수분석을 수행하고 지자체 중소하천에 최적화된 우량 및 수위 홍수 모니터링 기준을 수립하여 선제적 홍수대응을 할 수 있는 여건을 조성하였다. 또한 해당지자체의 우량 수위관측소의 분포와 용수전용댐 및 농업용저수지를 반영하여 유역특성을 고려한 홍수분석모형을 구축하였으며, 예상강우에 따른 주요 지점별 예상수위 및 도달시간 분석으로 지자체 담당자의 홍수대응을 지원하고자 한다. 하천 수위국 기준의 우량 알람은 하천 수위 상승 전 예비 알람의 성격으로 수위국의 수위가 상승하기 전 대비할 수 있는 선제적 대응 예방시간 확보에 도움이 될 수 있다. 또한 단계별 수위모니터링 기준에 의거하여 보행자 및 차량 통행제한 등의 조치를 취할 수 있으며, 제방월류 전 사전대응시간을 확보할 수 있어 자자체에서 능동적으며 선제적인 홍수 대응이 가능할 것으로 판단된다. 하지만 하천 수위국의 상황이 홍수에 따라 변화될 수 있으며, 홍수량 재산정 또는 하천기본 계획의 재수립 등 정책적, 현실적인 상황의 변화로 인해 모니터링 기준이 변화되어야 하는 경우에는 지속적인 보완이 필요할 것으로 사료된다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.5
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• pp.93-103
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• 2005

In this paper, we propose a RST resistant robust logo embedding technique for multimedia copyright protection Geometric manipulations are challenging attacks in that they do not introduce the quality degradation very much but make the detection process very complex and difficult. Watermark embedding in the normalized image directly suffers from smoothing effect due to the interpolation during the image normalization. This can be avoided by estimating the transform parameters using an image normalization technique, instead of embedding in the normalized image. Conventional RST resistant schemes that use full frame transform suffer from the absence of effective perceptual masking methods. Thus, we adopt $8\times8$ block DCT and calculate masking using a spatio-frequency localization of the $8\times8$ block DCT coefficients. Simulation results show that the proposed algorithm is robust against various signal processing techniques, compression and geometrical manipulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.187-192
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• 2021

This study proposes a system for take-off in a forest or similar complex environment using an object detector. In the simulator, a raspberry pi is mounted on a quadcopter with a length of 550mm between motors on a diagonal line, and the experiment is conducted based on edge computing. As for the images to be used for learning, about 150 images of 640⁎480 size were obtained by selecting three points inside Kunsan University, and then converting them to black and white, and pre-processing the binarization by placing a boundary value of 127. After that, we trained the SSD_Inception model. In the simulation, as a result of the experiment of taking off the drone through the model trained with the verification image as an input, a trajectory similar to the takeoff was drawn using the label.