• 융합보안논문지
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• 제20권5호
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• pp.33-39
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• 2020

이동 노드로만 구성된 MANET은 모든 노드들이 라우터 역할을 수행한다. 하지만 노드들의 빈번한 이동으로 인한 동적인 토폴로지는 라우팅 성능을 떨어뜨리고 많은 보안 취약점의 원인이기도 하다. 따라서 MANET의 성능을 좌우할 수 있는 라우팅 기법에는 보안이 반드시 적용되어야 한다. 본 논문에서는 영역-키 기반 보안 라우팅 기법 적용을 통해 다양한 라우팅 공격에 효율적으로 대응하고, 안전한 데이터 전송을 위한 기법을 제안하였다. 제안한 기법에서는 영역 기반 네트워크 구조를 이용하였으며, 각 영역내 멤버 노드들을 관리하는 관리 노드를 이용하였다. 또한 각 노드들에 키를 발급하여 이를 이용한 라우팅 기법을 적용함으로써 공격 노드로 부터의 피해를 최소화하였다. 영역 관리 노드는 라우팅 정보를 암호화하기 위한 키 발급과 발급 정보를 관리한다. 데이터 전송을 원하는 멤버 노드는 영역 관리 노드로부터 발급받은 키를 이용하여 라우팅 정보를 암호화한 후, 이를 이용하여 경로 발견을 수행하게 된다. 제안한 기법의 향상된 성능은 CBSR, ARNA 기법과 비교 실험을 통하여 확인하였으며, 실험을 통해 우수한 성능을 확인할 수 있었다.

• 해양안보
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• 제8권1호
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• pp.1-39
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• 2024

본 연구는 현재까지 중국의 해양 회색지대 전략에 관한 국내 연구들이 기존 미국 주도의 회색지대 연구의 분석 결과를 답습하고 있으며, 대응책에 관해서도 원론적 입장과 방향만이 제시된 '선언적·개념적' 수준에 머물러 있다는 문제의식에서 시작되었다. 필자는 위 문제점 극복을 위해 중국은 자국 고유의 전략문화를 구성하는 '삼전'을 기반으로 해양 회색지대 전략을 전개한다는 인식 하에 남중국해, 동중국해, 그리고 서해와 이어도 일대에서 전개 중인 해양 회색지대 전략을 삼전의 영역별로 분석하였다. 분석결과 추후 서해와 이어도 일대를 차지하기 위해 중국의 해양 회색지대 전략은 보다 공세성을 띌 것으로 예측되며, 우리해군 대응전략 개념으로 『중국 해양 회색지대 전략의 기반인 '삼전'의 전개 효과를 '무력화'시켜 중국이 유도하는 점진적인 현상 변화를 멈추게 하고, 규범·규칙에 기반한 해양질서로 '환원'을 지속적으로 추구』를 제시하였다. 그리고 대응전략의 개념을 이행할 수 있는 '구체화·체계화'된 대응책을 본 연구에서 제시하였다.

• Current Optics and Photonics
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• 제4권1호
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• pp.9-15
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• 2020

Fresnel zone plates have been widely used in many applications, such as x-ray telescopes, microfluorescence, and microimaging. To obtain an x-ray Fresnel zone plate, many fabrication methods, such as electron-beam etching, ion-beam etching and chemical etching, have been developed. Fresnel zone plates fabricated by these methods will inevitably lead to some nonideal factors, which have an impact on the focusing characteristics of the zone plate. In this paper, the influences of these nonideal factors on the focusing characteristics of the zone plate are studied systematically, by numerical simulations based on scalar diffraction theory. The influence of the thickness of a Fresnel zone plate on the absolute focusing efficiency is calculated for a given incident x-ray's wavelength. The diffraction efficiency and size of the focal spot are calculated for different incline angles of the groove. The simulations of zone plates without struts, with regular struts, and with random struts are carried out, to study the effects of struts on the focusing characteristics of a zone plate. When a Fresnel zone plate is used to focus an ultrashort x-ray pulse, the effect of zone-plate structure on the final pulse duration is also discussed.

• Advances in concrete construction
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• 제1권3호
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• pp.239-252
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• 2013

Mortar microstructure is considered as a three-phase composite material, which is cement paste, fine aggregate and interfacial transition zone. Interfacial transition zone is the weakest link between the cement paste and fine aggregate, so it has a significant role to determine the properties of cementitious composites. In this study, specimens (w/c = 0.35, 0.45, 0.55) with various volume fractions of fine aggregate ($V_f$ = 0, 0.1, 0.2, 0.3 and 0.4) were cast and tested. To predict the equivalent migration coefficient ($M_e$) and migration coefficient of interfacial transition zone ($M_{itz}$), double-inclusion method and Mori-Tanaka theory were used to estimate. There are two stages to estimate and calculate the thickness of interfacial transition zone (h) and migration coefficient of interfacial transition zone ($M_{itz}$). The first stage, the data of experimental chloride ion migration coefficient ($M_s$) was used to calculate the equivalent migration coefficient of fine aggregate with interfacial transition zone ($M_e$) by Mori-Tanaka theory. The second stage, the thickness of interfacial transition zone (h) and migration coefficient of interfacial transition zone ($M_{itz}$) was calculated by Hori and Nemat-Nasser's double inclusion model. Between the theoretical and experimental data a comparison was conducted to investigate the behavior of interfacial transition zone in mortar and the effect of interfacial transition zone on the chloride migration coefficient, the results indicated that the numerical simulations is derived to the $M_{itz}/M_m$ ratio is 2.11~8.28. Additionally, thickness of interfacial transition zone is predicted from $10{\mu}m$, 60 to $80{\mu}m$, 70 to $100{\mu}m$ and 90 to $130{\mu}m$ for SM30, M35, M45 and M55, respectively.

• 해양안보
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• 제1권1호
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• pp.119-148
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• 2020

본 연구는 그레이존에 대한 주변국의 전략을 살펴보고 한국의 그레이존 전략을 모색하는 것을 목적으로 한다. 그레이존에 대한 개념은 국가마다 분야마다 다양하게 나타나고 있다. 국제관계에서 그레이존은 전쟁과 평화의 사이라는 포괄적인 공간이다. 해양에서의 그레이존은 향후 미중경쟁이 본격화되고 대리전이 가능한 불안정한 공간으로 그레이존의 전략적인 관리가 필요하다. 본 연구는 해양안보 분야에서의 그레이존의 개념을 정리하고, 주요국들의 그레이존 전략을 살펴본 후 한국의 그레이존 대응방안을 제시한다. 특히 그레이존에 대한 복합해양지전략 분석틀에 근거한 문제의 명확화와 해양상황파악(MDA) 추진체계 확립을 위한 해경강화 및 해군과의 정보공유의 강화가 필요하다고 주장한다. 본 연구에서 시도한 복합해양지전략적 이론틀은 한국의 다양한 그레이존 이슈들의 성격을 파악하고 사안별 대응전략을 마련하는 데 도움이 될 것으로 기대한다. 또한 일본과 중국을 비롯한 주변국들의 그레이존 전략을 확인하고 한국에 접목하며 향후 강화되는 미중 경쟁 속 그레이존의 평화화 가능성에 대해 모색한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1031-1033
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• 2005

This paper presents a system of handwritten numerals recognition, which is based on Ant-miner algorithm (data mining based on Ant colony optimization). At the beginning, three distinct fractures (also called attributes) of each numeral are extracted. The attributes are Loop zones, End points, and Feature codes. After these data are extracted, the attributes are in the form of attribute = value (eg. End point10 = true). The extraction is started by dividing the numeral into 12 zones. The numbers 1-12 are referenced for each zone. The possible values of Loop zone attribute in each zone are "true" and "false". The meaning of "true" is that the zone contains the loop of the numeral. The Endpoint attribute being "true" means that this zone contains the end point of the numeral. There are 24 attributes now. The Feature code attribute tells us how many lines of a numeral are passed by the referenced line. There are 7 referenced lines used in this experiment. The total attributes are 31. All attributes are used for construction of the classification rules by the Ant-miner algorithm in order to classify 10 numerals. The Ant-miner algorithm is adapted with a little change in this experiment for a better recognition rate. The results showed the system can recognize all of the training set (a thousand items of data from 50 people). When the unseen data is tested from 10 people, the recognition rate is 98 %.

• Ocean and Polar Research
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• 제25권4호
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• pp.519-528
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• 2003

Species composition and community structure of marine benthic community were studied in the intertidal zone of Jijindo Island, Gwangyang Bay. A total of 85 species of benthic marine plants including the 5 Cyanophyta, 9 Chlorophyta, 13 Phaeophyta, 56 Rhodophyta and 2 Magnoliophyta that were listed. The community structure was represented by Gelidium divaricatum in the upper zone, Celidium divalicatum and Ulva pertusa in the middle, and Ulva pertusa, Chondria crassicaulis, Chondracanthus intermedia and Sargassum thunbergii in the lower intertidal zone. The dominant species in the rnscro-zoobenthic community were Chthamalux challengeri in the upper and middle, Littorina brevicula between the upper and middle, and Mytilus edulis and Crassostrea gigas in the middle and lower intertidal zones. The economic benthic organisms such as Undaria pinnatifida, Mytilus edulis, and Crassostrea gigas found in the lower intertidal zone were frequently disturbed due to their collection by local resident. Therefore, it is necessary to record the correct information pertaining to these cases. The species diversity indices estimated kom different sources were quite different. They were 2.22 derived from frequency, 1.67 based on coverage, 2.17 based on sum of frequency and coverage and 2.04 derived from importance value. Species diversity and number of algal species in Gwangyang Bay have noticeably decreased, compared with their previously reported status. It is estimated that their decreases were caused by changes in the marine environment, especially pertaining to the polychaete community resulting from reclamation and dredging activity undertaken for the industrial development.

• 상하수도학회지
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• 제25권4호
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• pp.535-546
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• 2011

The study area investigated in this research is Hwaseong city, Gyeonggi-Do where small scale development is currently in progress. For the last three years, we carried out the environmental and ecological assessment by using data from The Ministry of Environment and Han River Basin Environmental Office. Most of development works in Hwaseong city, Gyeonggi-Do are small scale developments which are related with factory and distribution complex based on individual laws and regulations. However, environmental and ecological assessment is not being sufficiently reflected beforehand. Especially, because the development takes place mainly in the outskirts of the city, the fine forest is continuously being damaged. We analyzed changes in green zone area caused by the developments. As a result, the percentage of original green zone was decreasing while the percentage of artificial green zone was increasing. We should maintain the percentage of the original green zone in order to conserve natural environment. In the past three years, the damage of the DGN (Degree of Green Naturality) 7 area that has high conservative value was little, but, there was serious damage in the area of DGN 6. In order to conserve natural environment, political and institutional investigation should be seriously carried out for mitigation of environmental and ecological damages.

• 유통과학연구
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• 제20권3호
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• pp.23-31
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• 2022

Purpose: The purpose of this study is to analyze the Safety and Logistical Distribution Management system in Thailand's Highway Work Zone based on data from Logistics drivers. Accidents in highway construction zones have caused enormous casualties in Thailand yearly. Statistical data shows evidence of correlation between numbers of accidents and drivers' recklessness. Research design, data, and methodology: In this study, we conducted an in- depth interview with 414 logistics drivers and highway construction workers in Khon Kaen province, Thailand. The data was collected based on 63 questionnaires aiming at capturing factors contributing to the risk of safety and cause of accidents in logistic infrastructures such as Highway work zone. Results: The result reveals two significant factors affecting safety in highway work zone, which includes construction environment and safety management system. Moreover, the result shows that feeling of afraid and confused while driving within the construction zones significantly affecting driver's risk of having an accident. Conclusions: The findings of this study offer that a strategic planning and evaluation of the logistics drivers' satisfaction and construction workers' participation to mitigate highway accidents at construction zones and that drivers' knowledge and perception toward construction safety management plays a significant role in preventing highway accidents at the construction areas.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.381-382
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• 2023

Frequent accidents occur when workers at construction sites leave the safety zone, and particularly in the past 5 years, 9 fatal accidents occurred at the Korea Railroad Corporation due to train accidents on other tracks during track work. With the Severe Accident Punishment Act taking effect in January 2022, it is a priority to secure a safe work environment for workers at industrial (construction) sites. Therefore, there is a need to manage workers' departure from the safety zone (construction zone) and to facilitate communication within the construction zone. In this study, a mobile edge computing CCTV system is proposed that uses geofencing to determine whether workers are working in the danger zone, which can judge and respond in real-time to the ever-changing field environment. The proposed system is mobile and flexible, rather than server-based fixed CCTV. However, since it is designed mainly based on images, it has limitations in recognition rate depending on the environment such as distance, viewing angle, and illumination. As a way to compensate for this, it is required to develop more reliable equipment by combining technologies such as LiDAR and Radar.