• 한국항행학회논문지
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• 제23권3호
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• pp.237-244
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• 2019

SBAS는 실시간으로 사용자에게 GNSS 궤도 및 시계, 전리층 보정정보와 이에 대한 무결성정보를 제공하여 SBAS 사용 시 정밀한 위치추정이 가능하다. 각 국의 SBAS 개발 및 추가 지상관측소 설치로 SBAS 서비스 영역이 확대됨에 따라 2개의 SBAS 서비스 영역이 겹쳐 다중 SBAS 신호가 수신되는 영역이 존재하는데, 이에 대한 신호 선택 방법에 관한 연구는 진행되지 않았다. 이에 본 연구에서는 WAAS와 EGNOS 정보가 동시에 전송되는 영역에서 WAAS 정보 우선 사용 방법, EGNOS 정보 우선 사용 방법, 그리고 보정정보 오차 공분산 비교 선택 방법을 사용하여 저궤도위성에 SBAS 정보를 적용한 후 위치추정 결과를 비교하였다. WAAS 정보를 우선으로 사용할 때 3D 위치오차는 2.57 m로 가장 작았으며, 오차 공분산 비교 방법을 사용했을 경우에는 WAAS와 EGNOS의 관측소와 가장 먼 중첩 영역 중심에서 위치추정 정확도가 가장 높았다. EGNOS 정보를 우선 사용 시 중첩 영역의 EGNOS와 가까운 동쪽 지역에서 WAAS 우선 사용 방법보다 위치오차가 8% 더 작았다.

• 한국안전학회지
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• 제30권5호
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• pp.108-113
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• 2015

Plastic injection moulding machine is widely used for many industrial field. It is classified into mandatory safety certification machinery in Industrial Safety and Health Act because of its high hazard. In order to prevent industrial accidents by plastic injection moulding machine, it is necessary for designer to identify hazardous factors and assess the failure modes to mitigate them. This study tabulates the failure modes of main parts of plastic injection moulding machine and how their failure has affect on the machine being considered. Failure Mode & Effect Analysis(FMEA) method has been used to assess the hazard on plastic injection moulding machine. Risk and risk priority number(RPN) has been calculated in order to estimate the hazard of failures using severity, probability and detection. Accidents caused by plastic injection moulding machine is compared with the RPN which was estimated by main regions such as injection unit, clamping unit, hydraulic and system units to find out the most dangerous region. As the results, the order of RPN is injection unit, clamping unit, hydraulic unit and system units. Barrel is the most dangerous part in the plastic injection moulding machine.

• 한국물환경학회지
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• 제23권4호
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• pp.440-447
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• 2007

This paper is dealing with recent hot issues related with copper toxicity and its criteria, which was caused by a new government policy relocating some industries discharging priority-water quality pollutants from the watershed of Han River to other regions. Author is not interested in arguments between two sides of anti- and pro-policy but would like to go over status of copper pollution and its management and regulatory policy in Korea. From the data of published Research Journals and Reports, it can be concluded that copper is very common metal not only in the effluent from publically owned wastewater treatment plants, but also as a non-point source pollutant in the rainfall runoff. In addition, there have been very few studies personal interests, not by National Fund Basis. In order to enforce a new regulation, national-wide macro and micro-mass balance work of heavy metals should be performed in advance. In particular, background concentration and measurement errors have to be clearly defined before a new standard or criteria is established. The new standard has to be acceptable in terms of the best available technology and cost.

• 한국항해항만학회지
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• 제41권6호
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• pp.437-444
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• 2017

위험 유해물질(HNS) 유출사고를 대비하기 위하여 본 연구에서는 지역별 산업 집중도를 지수화하여 동향을 파악하기 위해 쓰이는 집중도지수를 활용하여 HNS 사고의 지역별 집중도를 확인하였다. 이는 HNS를 포함한 해양 유출사고 데이터를 바탕으로 HNS 사고 규모 집중도지수와 HNS 사고 빈도 집중도지수를 수치화하여 하나의 값인 HNS 사고 집중도지수를 제시하는 방식이다. 도출된 지역별 HNS 사고집중도 지수값를 바탕으로 울산을 HNS 대비 최우선 지역, 여수, 부산, 태안을 HNS 대비 우선지역, 군산, 목포, 완도, 인천, 통영, 평택, 포항을 HNS 대비 필요지역, 그 밖에 해양유출사고가 발생하지 않은 동해, 보령, 부안, 서귀포, 속초, 제주, 창원을 HNS 대비 지원지역으로 그룹화하여 대비측면의 우선순위를 설정하였다.

• 한국환경복원기술학회지
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• 제26권5호
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• pp.19-32
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• 2023

The fragmentation of habitats resulting from human activities leads to the isolation of wildlife and it also causes wildlife-vehicle collisions (i.e. Road-kill). In that sense, it is important to predict potential habitats of specific wildlife that causes wildlife-vehicle collisions by considering geographic, environmental and transportation variables. Road-kill, especially by large mammals, threatens human safety as well as financial losses. Therefore, we conducted this study on roe deer (Capreolus pygargus tianschanicus), a large mammal that causes frequently Road-kill in Jeju Island. So, to predict potential wildlife habitats by considering geographic, environmental, and transportation variables for a specific species this study was conducted to identify high-priority restoration sites with both characteristics of potential habitats and road-kill hotspot. we identified high-priority restoration sites that is likely to be potential habitats, and also identified the known location of a Road-kill records. For this purpose, first, we defined the environmental variables and collect the occurrence records of roe deer. After that, the potential habitat map was generated by using Random Forest model. Second, to analyze roadkill hotspots, a kernel density estimation was used to generate a hotspot map. Third, to define high-priority restoration sites, each map was normalized and overlaid. As a result, three northern regions roads and two southern regions roads of Jeju Island were defined as high-priority restoration sites. Regarding Random Forest modeling, in the case of environmental variables, The importace was found to be a lot in the order of distance from the Oreum, elevation, distance from forest edge(outside) and distance from waterbody. The AUC(Area under the curve) value, which means discrimination capacity, was found to be 0.973 and support the statistical accuracy of prediction result. As a result of predicting the habitat of C. pygargus, it was found to be mainly distributed in forests, agricultural lands, and grasslands, indicating that it supported the results of previous studies.

• 제어로봇시스템학회논문지
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• 제10권10호
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• pp.855-868
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• 2004

There are several types of singularities in controlling robotic manipulators: kinematic singularity, algorithmic singularity, semi-kinematic singularity, semi-algorithmic singularity, and representation singularity. The kinematic and algorithmic singularities have been investigated intensively because they are not predictable or difficult to avoid. The problem with these singularities is an unnecessary performance reduction in non-singular region and the difficulty in performance tuning. Tn this paper, we propose a method of avoiding kinematic and algorithmic singularities by applying a task reconstruction approach while maximizing the task performance by calculating singularity measures. The proposed method is implemented by removing the component approaching the singularity calculated by using singularity measure in real time. The outstanding feature of the proposed task reconstruction method (TR-method) is that it is based on a local task reconstruction as opposed to the local joint reconstruction of many other approaches. And, this method has dynamic task priority assignment feature which ensures the system stability under singular regions owing to the change of task priority. The TR-method enables us to increase the task controller gain to improve the task performance whereas this increase can destabilize the system for the conventional algorithms in real experiments. In addition, the physical meaning of tuning parameters is very straightforward. Hence, we can maximize task performance even near the singular region while simultaneously obtaining the singularity-free motion. The advantage of the proposed method is experimentally tested by using the 7-dof spatial manipulator, and the result shows that the new method improves the performance several times over the existing algorithms.

• Nuclear Engineering and Technology
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• 제40권1호
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• pp.37-48
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• 2008

Flow fields inside feeder pipes have been simulated numerically using a CFD (computational fluid dynamics) code to calculate the shear stress distribution, which is the most important factor in predicting the local regions of feeder pipes highly susceptible to FAC (flow-accelerated corrosion)-induced wall thinning. The CFD approach, with schemes used in this study, to simulate the flow situations inside the CANDU feeder pipes has been verified as it showed a good agreement between the investigation results for the failed feedwater pipe at Surry unit 2 plant in the U.S. and the CFD calculation. Sensitivity studies of the three geometrical parameters, such as angle of the first and second bends, length of the first span between the grayloc hub and the first bend, and length of the second span between the first and the second bends have been performed. CFD analysis reveals that the local regions of feeder pipes of Wolsung unit 1 in Korea, on which wall thickness measurements have been performed so far, are not coincident with the worst regions predicted by the present CFD analysis located in the connection region of straight and bend pipe near the inlet part of the bend intrados. Finally, based on the results of the present CFD analysis, a guide to the selection of the weakest local positions where the measurement of wall thickness should be performed with higher priority has been provided.

• International Journal of Computer Science & Network Security
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• 제21권6호
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• pp.61-70
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• 2021

Within the article, forms of innovation structures are systematized, and those that exist in Ukraine are identified, their features, purpose and functions are clarified, activities and current state of their functioning are analyzed. It is proved that in the conditions of digital economy, domestic innovation structures are underdeveloped and do not fulfill their leading role at the present stage of innovative development of the country. To understand the importance of effective operation of innovation infrastructure, the main world models of innovation development are considered, and the directions of using the experience of their functioning for Ukraine are determined. The main indicators of innovation activity of Ukraine in the context of regions are analyzed. There is a significant differentiation of innovation indicators in the regional context. The cartographic analysis of innovative activity of regions is presented. The mechanism of definition and implementation of priority directions of innovative activity in the context of the digital economy development is offered.

• 한국가스학회지
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• 제20권5호
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• pp.82-88
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• 2016

산업의 발전을 위해 자원개발이 필수적인 현시대에 육상자원의 고갈로 인해 극한지에 관심이 몰리고 있다. 그러나 극한지 자원개발을 위해서는 극한지의 환경을 이해하고 이에 맞는 건설기술 확보가 우선되어야 한다. 극한지에서 자주 나타나는 외부환경 중 특히 융해침하는 자원을 이송하는데 필수적인 배관에 치명적인 영향을 준다. 따라서 배관이 융해침하에 의해 어떤 영향을 받는지 예측하고 분석하는 것이 중요하다. 본 연구에서는 융해침하 시 배관의 매설깊이에 따른 영향을 분석하기 위해 3차원 모델을 개발하여 유한요소해석을 진행하였다. 이러한 극한지의 환경과 배관해석을 참고하여 Elasto-plastic이 고려된 배관이 받는 응력 및 변위를 분석하고 경향성을 알아보았다.

• 대한토목학회논문집
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• 제37권5호
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• pp.855-862
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• 2017

대한민국은 지난 반세기간 성장위주의 정책을 통하여서 경제적, 문화적, 사회적으로 급속한 발전을 이루었다. 하지만 거점개발방식으로 인하여서 비대한 도시와 낙후된 지역이 생겼다. 이에 따라서 국가에서는 많은 낙후지역 개발정책들을 펼쳐왔으나 많은 문제점들을 가졌다. 그 이유는 소관 부처가 많고 사업의 종류가 다양함으로 인해 나타난다. 또한 개발 우선순위가 객관적인 지표에 근거하지 않고 각 지자체에 분배 식으로 사업이 수행되는 형태이기 때문이다. 기존의 연구된 지역에 대한 지표연구는 도 또는 시, 군등 대단위에서만 분석되어있고 소단위 지역의 사업의 순서를 선정하는데 어려움을 가진다. 이에 따라서 지역에 대한 지표선정을 통해 소규모 낙후지역의 효율적인 개발을 위한 의사결정 지원 시스템로 사용하고자 한다.