• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.40.1-40.1
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• 2015

Off-axis reflective optical systems have attractive advantages relative to their on-axis or refractive counterparts, for example, zero chromatic aberration, no obstruction, and a wide field of view. For the efficient operation of off-axis reflective system, the surface accuracy of freeform mirrors should be higher than the order of wavelengths at which the reflective optical systems operate. Especially for applications in shorter wavelength regions, such as visible and ultraviolet, higher surface accuracy of freeform mirrors is required to minimize the light scattering. In this work, we propose the error compensation algorithm (ECA) for the correction of wavefront errors on freeform mirrors. The ECA converts a form error pattern into polynomial expression by fitting a least square method. The error pattern is measured by using an ultra-high accurate 3-D profilometer (UA3P, Panasonic Corp.). The measured data are fitted by two fitting models: Sag (Delta Z) data model and form (Z) data model. To evaluate fitting accuracy of these models, we compared the fitted error patterns with the measured error pattern.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.1119-1120
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• 2017

본 논문은 전기 누진요금제의 문제점과 이를 해결하기 위한 해결책으로 드론을 이용한 전력량계 자동 검침 시스템을 제안한다. 전력 사용량을 줄이기 위해 도입된 누진요금제가 도입 의도와는 달리 검침인력부족으로 인한 가구별 검침 시간 차이로 인해 같은 전기량을 사용하더라도 더 많은 요금을 부과 받게 되는 가정이 발생함에 따라 형평성에 대한 논란을 낳았다. 따라서 인건비 상승을 피하고 이를 해결하기 위한 방안으로 검침원을 대신해 드론이 공중에서 비행하며 여러 가구를 대상으로 사용량 정보를 수집하는 시스템을 제안한다. 이를 통해 검침 시간의 차이를 줄여 형평성을 보장하고 측정 데이터를 수기로 기록할 필요 없이 즉각적으로 데이터화 할 수 있다. 또한 사람이 닿기 힘든 오지에서 활용한다면 인력을 사용하는 것 보다 효과적이고 더 나은 편의성을 제공해 줄 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.259-263
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• 2015

The vulnerabilities related to Flash player which is widely used in internet browsers and office programs are gradually increased. To detect Flash malwares, previous work focuses on predefined features of ActionScript. However above work cannot detect new/mutated Flash malwares, since predefined features could not cover the new patterns of new/mutated Flash mawares. To solve this problem, we propose a Flash malware detection method that uses machine learning to learn Flash Tag patterns and classify Flash by using machine learning.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.297-298
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• 2014

최근 사회 전반적으로 빅데이터가 주목 받고 있다. 기존 대중교통 안내 어플리케이션의 경우 현재 교통정보를 기준으로 추천하기 때문에 실제로는 최적의 경로가 아닌 경로가 추천될 수 있다. 본 논문에서는 빅데이터 분석을 통한 실시간 최적 교통 경로 안내 시스템을 설계하고 구현한다. 설계한 시스템은 과거 교통 정보를 분석하여 각 경로들의 교통상황을 예측하여 경로 이동 계획을 설정해준다. 또한 중간에 교통상황이 급변하여 경로를 수정해야할 필요가 있을 때 사용자에게 알림을 주고 그에 대한 조치를 취할 수 있도록 지원한다.

• Atmosphere
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• v.26 no.1
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• pp.47-58
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• 2016

On 10 July 2014, tornado outbreak occurred over Goyang province in Korea. This was the first supercell tornado ever reported or documented in Korea. The characteristics of the supercell tornado were investigated using an X-band polarimetric radar, surface meteorological observation, wind profiler, and operational numerical weather prediction (Regional Data Assimilation and Prediction System, RDAPS). The supercell tornado developed along a preexisting dryline that was contributed to surface wind shear. The radar analyses examined here show that the supercell tornado indicated a hook echo with mesocyclone. The decending reflectivity core as well was detected before tornadogenesis and prior to intensification of supercell. The supercell tornado exhibited characteristics similar to typical supercell tornado over the Great Plains of the United States, such as hook echo, bounded weak echo region, and slower movement speed relative to the mean wind. Compared to the typical supercell tornado over U.S., this tornado showed horizontal scale of the mesocyclone was relatively smaller and left-mover.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.1
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• pp.9-15
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• 2020

Nitrogen vacancy center (NV center) in diamond has recently been appeared as a promising candidate for hyperpolarization applications due to its optical pumping property by laser. Optically Detected Magnetic Resonance (ODMR) has been used as a conventional method to obtain the resonance spectrum of NV centers. ODMR, however, has a shortcoming of sensitivity and a limitation of subjects, such that the degree of hyperpolarization can hardly be estimated, and that the spins other than NV centers are invisible. In contrast, Electron Spin Resonance (ESR) spectroscopy is known to proportionally reflect the degree of spin polarization. In this work, we successfully observed the optically-induced hyperpolarization of NV spins in diamond through CW-ESR spectroscopy with an X-band system. All the NV peaks were identified by calculating the eigenvalues of NV spin Hamiltonian. The intensities of NV peaks were enhanced over 240 times after optical pumping. The enhanced peaks corresponding to the transition from |m_s=0> to |m_s=-1> revealed inverted phases, while other peaks remained in-phase. The optically-induced hyperpolarization on NV spins can be a useful polarization source, leading to ¹³C nuclear hyperpolarization in diamond.

• Journal of the Korean Magnetic Resonance Society
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• v.23 no.1
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• pp.12-19
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• 2019

A former study has shown that the spin-lattice relaxation time ($T_1$) in cancerous prostate tissue had enhanced contrast at an ultra-low magnetic field, $132{\mu}T$. To study the field dependence and the origin of the contrast we measured $T_1$ in pairs of ex-vivo prostate tissues at the Earth's magnetic field. A portable and coil-based nuclear magnetic resonance (NMR) system was adopted for $T_1$ measurements at $40{\mu}T$. The $T_1$ contrast, ${\delta}=1-T_1$ (more cancer)/$T_1$(less cancer), was calculated from each pair. Additionally, we performed pathological examinations such as Gleason's score, cell proliferation index, and micro-vessel density (MVD), to quantify correlations between the pathological parameters and $T_1$ of the cancerous prostate tissues.

• International journal of advanced smart convergence
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• v.10 no.3
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• pp.131-142
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• 2021

Recently, there has been an active service that provides customized news to news subscribers. In this study, we intend to design a customized news service system through Deep Learning-based Social Network Service (SNS) activity analysis, applying real news and avoiding fake news. In other words, the core of this study is the study of delivery methods and delivery devices to provide customized news services based on analysis of users, SNS activities. First of all, this research method consists of a total of five steps. In the first stage, social network service site access records are received from user terminals, and in the second stage, SNS sites are searched based on SNS site access records received to obtain user profile information and user SNS activity information. In step 3, the user's propensity is analyzed based on user profile information and SNS activity information, and in step 4, user-tailored news is selected through news search based on user propensity analysis results. Finally, in step 5, custom news is sent to the user terminal. This study will be of great help to news service providers to increase the number of news subscribers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.3
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• pp.429-438
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• 2021

The mandatory installation of the ECDIS (Electronic Chart Display and Information System) became an important navigational equipment for navigation officer. In addition, ECDIS is a key component of the ship's digitalization in conjunction with various navigational equipment. Meanwhile, cyber-attacks emerge as a new threat along with digitalization. Damage caused by cyber-attacks is also reported in the shipping sector, and IMO recommends that cybersecurity guidelines be developed and included in International Security Management (ISM). This study analyzed the cybersecurity hazards of ECDIS, where various navigational equipment are connected. To this end, Importance-Performance Analysis (IPA) was conducted on navigation officer using ECDIS. As a result, the development of technologies for cyber-attack detection and prevention should be priority. In addition, policies related to 'Hardware and Software upgrade', 'network access control', and 'data backup and recovery' were analyzed as contents to be maintained. This paper is significant in deriving risk factors from the perspective of ECDIS users and analyzing their priorities, and it is necessary to analyze various cyber-attacks that may occur on ships in the future.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.57-65
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• 2023

In 2017, the International Maritime Organization (IMO) adopted MSC.428 (98), which recommends establishing a cyber-risk management system in Ship Safety Management Systems (SMSs) from January 2021. The 27th International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) also discussed prioritizing cyber-security (cyber-risk management) in developing systems to support Maritime Autonomous Surface Ship (MASS) operations (IALA guideline on developments in maritime autonomous surface ships). In response to these international discussions, Korea initiated the Korea Autonomous Surface Ship technology development project (KASS project) in 2020. Korea has been carrying out detailed tasks for cybersecurity technology development since 2021. This paper outlines the basic concept of ship network security equipment for supporting MASS ship operation in detailed task of cybersecurity technology development and defines ship network security equipment interface for MASS ship applications.