• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.92-98
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• 2001

When analyzing the scatting problem of multi-layered planar structures using closed-form Green's function, one of the main difficulties is that the numerical integrations for the evaluation of diagonal matrix elements converge slowly and are not so stable. Accordingly, even when the integration fur the singularity of type $e^{-jkr}/{\gamma}$, corresponding to the source dipole itself, is performed using such a method, this difficulty persists in the integration corresponding to the finite number of complex images. In order to resolve this difficulty, a new technique based upon the Gaussian quadrature in polar coordinates for the evaluation of the two-dimensional generalized exponential integral is presented. Stability of the algorithm and convergence is discussed. Performance is demonstrated for the example of a microstrip patch antenna.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.5
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• pp.870-878
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• 2008

The level of security of most sensor nodes that comprise the sensor networks is low, but because of the low computing power and small storage capacity, it is even very difficult to apply a security algorithm efficiently to the sensor nodes. Therefore, preventing the join of an illegal node to a sensor network is impossible, and the transmitting information is easily exposed and overheard when the transmitting algorithm of the sensor node is hewn. In this paper, we propose a group key management scheme for the sensor network using polar coordinates, so that the sensor nodes can deliver information securely inside a cluster and any illegal node is prevented from joining to the cluster where a sensor network is composed of many clusters. In the proposed scheme, all of the sensor nodes in a cluster set up the authentication keys based on the pivot value provided by the CH. The intensive simulations show that the proposed scheme outperforms the pair-wise scheme in terms of the secure key management and the prevention of the illegal nodes joining to the network.

• Journal of Convergence for Information Technology
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• v.11 no.10
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• pp.20-26
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• 2021

In this paper, we studied the rotation angle estimation methods required for image alignment in an image recognition environment. In particular, a rotation angle estimation method applicable to a low specification embedded-based environment was proposed and compared with the existing method using complex moment. The proposed method estimates the rotation angle through similarity mathcing of the 1D projection profile along the radial axis after converting an image into polar coordinates. In addition, it is also possible to select a method of using vector sum of the projection profile, which more simplifies the calculation. Through experiments conducted on binary pattern images and gray-scale images, it was shown that the estimation error of the proposed method is not significantly different from that of complex moment-based method and requires less computation and system resources. For future expansion, a study on how to match the rotation center in gray-scale images will be needed.

• Korean Journal of Optics and Photonics
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• v.33 no.6
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• pp.252-259
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• 2022

We have conducted a study to control the light-intensity distribution at the output end of a multimode optical fiber via estimating the transmission matrix. A circularly arranged Hadamard eigenmode phase distribution was implemented using a spatial light modulator, and the transmission matrix of a multimode optical fiber was experimentally obtained using a four-phase method. Based on the derived transmission matrix, the spatial phase distribution of light incident upon the optical fiber was adjusted via the spatial light modulator in advance, to focus the light at a desired position at the optical fiber output. The light could be focused with an intensity up to 359.6 times as high as that of the surrounding background signal at a specific position of the multimode fiber's output end, and the intensity of the focused beam was on average 104.6 times as large as that of the background signal, across the area of the multimode fiber's core.

• Journal of Space Technology and Applications
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• v.1 no.1
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• pp.76-84
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• 2021

Because solar panels of normal satellites are faced to the sun, the power generation by the Earth Albedo is almost neglected in satellite's power analysis. However, many cubesats don't have deployable solar panels and in this case the Earth Albedo is not negligible because solar panels are in six sides facing different directions. In this paper, we calculated satellite's power generation by the Earth Albedo. We divided the Earth's surface into grids based on polar coordinate system. We modeled power generation in each solar cell by reflection on these grids. We simulated 1 U cubesat which flies in sun synchronous orbit and 500 km altitude so that we calculated satellite's power generation by the Earth Albedo.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.7-13
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• 2022

Radio frequency fingerprinting refers to a methodology that extracts hardware-specific characteristics of a transmitter that are unintentionally embedded in a transmitted waveform. In this paper, we put forward a fingerprinting feature and deep learning structure that can identify the same type of Digital Mobile Radio(DMR) by inputting the in-phase(I) and quadrature(Q). We proposes using the magnitude in polar coordinates of I/Q as RF fingerprinting feature and a modified ResNet-1D structure that can identify them. Experimental results show that our proposed modified ResNet-1D structure can achieve recognition accuracy of 99.5% on 20 DMR.

• Lettere Italiane
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• no.57
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• pp.1-38
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• 2019

이탈리아의 전진이탈리아, 북부동맹, 오성운동당의 유럽회의주의는 이탈리아의 국내정치의 내부적 대립과 경쟁의 결과로 이해할 수 있다. 이들 세 정당들이 취한 유럽회의주의적 입장은 이탈리아 정치지형변화의 특수성에 기인하여 제한적으로 표출되었다. 이탈리아의 정부형성은 대단히 포괄적인 거대 연맹(coalision)의 형태로 이루어져 왔고, 각기 다른시대에 정부의 책임을 공유하였다. 이는 정당들의 유럽회의적인 실질적인 표현에 제한성으로 작용하였음은 분명해 보인다. 또한 전후 이탈리아의 정치 체계속에서 등장한 정당들은 극심한 분열과 대립의 구도속에서 반대정치세력에 대한 견제에 집중한 정치전략을 필요로 했다. 이들 정당은 당의 창설 초기부터 유럽회의적 사안을 주요한 정치적 이슈로 부각하지 않았다. 오히려, 초기집권동안 전진이탈리아의 정치기조는 친유럽적인 성향을 띤 것이었다. 정당은 긴축재정과 이민급증의 경제, 사회문제에 직면하여 유럽회의적으로 전환한 공공담론을 인식하면서, 선거지지를 확보하기 위한 포괄적 정치전략으로 반유럽통합 담론을 부각시켰다. 같은 맥락으로 북부동맹의 초반 정치기조는 연방주의 형성을 위한 유럽통합에 동조하는 입장이었지만, 정당의 주변화와 정치지지 하락에 직면하여 정당 회생을 위한 대안으로 유럽회의적 정치 입장으로의 전향을 시도하였다. 오성운동당 역시, 반유럽적 사안은 국내의 정치적 대립속에서 정당의 합리성을 강화하기 위한 전략으로 채택된 것이었다. 한편, 자국의 경제이익과 정체성 보존 및 사회질서를 위해 타인종을 배격하고 반유럽을 주장하는 우파 포퓰리즘 정당과 극우정당이 대중의 공감을 획득하고 이탈리아 의회내의 입지가 강화되는 현상은 이탈리아의 정당체계에서 유럽회의주의의 점증 변수로 작용될 여지로 이해된다. 이에 따라 이탈리아 유럽회의주의 전당의 정치전략적 변화는 향후 유럽통합의 방향성에 따라 매우 유동적으로 전개될 가능성이 엿보이며, 이에 대한 다양한 연구적 질문과 분석이 이루어져야 할 것으로 사료된다.

• Korean journal of communication and information
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• v.48
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• pp.170-190
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• 2009

The aim of this study is to examine the ideological orientation of Minjujungbo which was the first and the largest newspaper in Busan during the U.S. Military Government in Korea. For this purpose this study analyzed the personal history of the editorial staffs and the coverage of the three historical events. The events analyzed were the supporting statement to trusteeship by Korean Communist Party in Jan. 1946, the money counterfeit by Jungpansa in May, 1946 and the general strike in Sep. 1946. The coverages of Minjujungbo on these three events were compared with those of other newspapers which had shown the orientation of the rightist, the neutral, and the leftist respectively. Most of the editorial staffs had been involved the leftist movement but were not socialist to the core at that time. Most of them were the members of Pusanilbo which was published by Japanese in late colonial period. The coverages of Minjujungbo were analyzed to be similar to those of Seoulsinmun which was evaluated as the neutral. But the coverage of the general strike was analyzed as leftist slightly. In conclusion it can be said that the ideological orientation of Minjujungbo was the left-of-center.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.25-34
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• 1993

The long-term behavior, such as in excavation problems of weak medium, can be dealt with by the elasto-viscoplasticity models. In this paper, a combined formulation of elasto-viscoplasticity using boundary elements and finite elements without using internal cells is presented. The domain integral introduced due to the viscoplastic stresses is transformed into a boundary integral applying direct integration in cylindrical coordinates. The results of the developed boundary element analysis are compared with those from the explicit solution and from the finite element analysis. It is observed that the boundary element analysis without internal cells results in some error because of its deficiency in handling the nonlinearity in local stress concentration. Therefore, a coupled analysis of boundary elements and finite elements, in which finite elements are used in the area of stress concentration, is developed. The coupled method is applied to a time dependent inelastic problem with semi-infinite boundaries. It results in reasonable solution compared with other methods where relatively higher degree of freedoms are employed. Thus, it is concluded that the combined analysis may be used for such problems in the effective manner.

• Convergence Security Journal
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• v.18 no.2
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• pp.167-177
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• 2018

Major countries, such as the U.S., UK and Germany have reformed their national intelligence systems in the face of transnational, asymmetric and comprehensive threats since September 11, 2001 and have strengthened the intelligence capacity involved in countering terrorism and WMD proliferation, right/left extremism threats. The Korean Moon Jae-in government is preparing a reform plan to eliminate illegal political intervention and abuse of power by the National Intelligence Service(NIS) and to rebuild it as an efficient national intelligence agency for national security. In discussing the reform direction of the NIS, it is necessary to discuss in detail whether adopting a separate model of intelligence agencies to restrict domestic intelligence activities of the NIS and concentrate on foreign intelligence activities or establish new domestic intelligence agencies. Second, as for the issue of transferring anti-Communism investigation authority of the NIS to the police, it needs to be carefully considered in terms of balancing the efficiency and professionalism of intelligence agency activity in the context of North Korea's continuous military provocation, covert operations and cyber threats. Third, it should strive to strengthen the control and supervision functions of the administration and the National Assembly to ensure the political neutrality of the NIS in accordance with the democratization era, to guarantee citizens' basic rights and to improve the transparency of budget execution.