• 천문학회보
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• 제45권1호
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• pp.64.3-65
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• 2020

It has been studied that galaxies evolve following a typical trajectory on the phase space under the influence of deep gravitational potential of galaxy clusters. Similarly, the large-scale filaments could also affect the evolution of galaxies before falling into the clusters. In this study, using a dark matter-only cosmological simulation, N-Cluster Run, we explore the evolution of galaxies on the phase space drien by large-scale filaments. We find that galaxies around the filaments form a common trajectory on the phase space as well as cluster galaxies do. We also examine how these trajectories change depending on various physical parameters such as galaxy mass, initial distance of galaxies from large-scale filaments, and cluster mass.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 춘계학술대회
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• pp.277-279
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• 2022

Rapid Development and adoption of AIS as a survailance tool has resulted in widespread application of data analysis technology, in addition to AIS ship trajectory clustering. AIS data-based clustering has become an increasingly popular method for marine traffic pattern recognition, ship route prediction and anomaly detection in recent year. In this paper we propose a route waypoint extraction by clustering ships CoG variance trajectory using Density-Based Spatial Clustering of Application with Noise (DBSCAN) algorithm in both port approach channel and coastal waters. The algorithm discovers route waypoint effectively. The result of the study could be used in traffic route extraction, and more-so develop a maritime anomaly detection tool.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2006년도 춘계학술대회 논문집
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• pp.554-555
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• 2006

• 한국입자에어로졸학회지
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• 제7권2호
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• pp.49-57
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• 2011

서울의 대기오염, 특히 고농도 대기오염 사례는 시민 건강에 매우 부정적일뿐만 아니라, 일반 시민들이 서울시에 대해 느끼는 체감오염도에도 중요한 변수이다. 따라서 이러한 고농도 대기오염 사례의 원인을 규명하는 것은 과학적으로 중요할 뿐만 아니라 사회적으로도 중요한 문제이다. 2005년 7월 22일부터 31일 사이에 고농도 대기오염 사례가 관측되었다. 이 대기오염 사례에 대해 측정소 간의 시계열분석, 에어로졸 성분 분석, 궤적 분석 등의 종합적인 해석을 통해, 대기오염 사례가 국지적인 것이었는지, 외부 영향에 의한 것인지 규명 하였다. 측정 결과를 바탕으로 이 사례를 7월 22~27일(기간 1)과 28~31일(기간 2)의 두 기간으로 구분하였다. 우리나라의 도시대기측정소의 PM10 농도 추이를 분석한 결과, 기간 1에는 춘천의 PM10 농도와 3시간 후에 서울의 PM10 농도가 상관관계가 높았으며, 기간 2에는 중부 지방 전체의 PM10 농도 사이에 상관관계가 높았다. 기간 1에는 풍속이 점차 강해져서 오염물질이 희석되는 경향을 보였으며, 기간 2에는 풍속이 점차 약해져 정체성 특성을 보여 고농도가 계속 유지되었다. 관측한 PM2.5 이온 조성은 기간 1보다는 기간 2에 높았으며, 두 기간 모두, 서울의 평균 농도보다는 매우 높았다. 궤적분석 결과 기간 1에는 시계열 분석 결과와 일치하게, 공기덩어리가 중국에서 북한과 강원도를 거쳐 서울로 이동하였고, 기간 2에는 중국에서 직접 서울로 이동하였다. 현재는 북한의 대기오염물질 배출 정도나 대기오염도에 대한 자료가 부족하여 보다 상세한 분석이 힘들다. 그러나 북한의 영향이 상당할 것으로 보이므로 이에 대한 연구가 필요하다 (Kim et al., 2011). 이 연구 결과는 2005년 7월 하순에 서울에서 발생한 대기오염 에피소드는 외부 영향, 특히 중국 영향에 의한 것임을 보여준다. 그러나 같은 외부 영향이라도 공기의 이동 경로와 풍속에 따라 오염 특성이 달라지는 것을 확인하였다.

• 한국항해항만학회지
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• 제42권6호
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• pp.453-458
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• 2018

해상교통 분석은 대상 해역의 환경 특성을 파악하고, 선박의 교통 패턴을 분석하는 일련의 과정을 일컫는다. 이는 최근 해상 교통량이 늘어나고 관제 영역이 확장됨에 따라 그 필요성이 증가하고 있으며, 실제로 해상교통관제(VTS, Vessel Traffic Service)와 항만 시설의 안전성 평가에 적용되기도 한다. 본 논문에서는 공간정보 분석 방법 중 히트맵(heatmap)과 중심점(centroid) 기법을 이용하여 선박의 통항패턴을 분석하는 방법을 제안한다. 이 방법은 시간에 따라 공간적 특성이 변하는 항적 데이터를 분석하기에 적합한 방법이며, 실제 목포항에서 수집된 항적 데이터를 이용한 실험을 수행하였다. 실험에서는 시간대별 교통 밀도와 중심점 분석을 수행하였고, 이를 통해 해상교통의 공간적 변화를 쉽게 식별할 수 있었으며, 제안하는 방법이 해상교통 분석법으로 활용될 수 있음을 확인하였다.

• 한국환경과학회지
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• 제21권7호
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• pp.815-824
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• 2012

The purpose of this study was to analyze the meteorological characteristics of wintertime high PM10 concentration episodes in Busan. $PM_{10}$ concentration has been reduced for the past four years and recorded near or exceeded 100 ${\mu}g/m^3$ (national standard of $PM_{10}$). High concentration episodes in Busan were 6 case, $PM_{2.5}/PM_{10}$ ratio was 0.36~0.39(mean 0.55). High $PM_{10}$ concentration occurred during higher air temperature, more solar radiation and sunshine, lower relative humidity, and smaller cloud amount. Synoptically, it also occurred when Busan was in the center or the edge of anticyclone and when sea breeze intruded. An analysis of upper air sounding showed that high $PM_{10}$ concentration occurred when surface inversion layer and upper subsidence inversion layer existed, and when boundary layer depth and vertical mixing coefficient were low. An analysis of backward trajectory of air mass showed that high $PM_{10}$ concentration was largely affected by long range transport considering that it occurs when air mass is intruded from China.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2000-2003
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• 2003

In recent years, robots have been used widely in industrial field and have been expanded as a result of continuous research and development for high-speed and miniaturization. The goal of this paper is to design the serial manipulator through kinematic analysis and to control the position and orientation of end-effector with respect to time. In general, a structure of industrial robot consists of several links connected in series by various types of joints, typically revolute and prismatic joints. The movement of these joints is determined in inverse kinematic analysis. Compared to the complicated structure of parallel and hybrid robot, open loop system retains the characteristic that each link is independent and is controlled easily. AC servo motor is used to place the robot end-effector toward the accurate point with the desired speed and power while it is operated by position control algorithm. The robot end-effector should trace the given trajectory within the appropriate time. The trajectory of end-effector can be displayed on the monitor of general personal computer through Opengl program.

• 한국대기환경학회지
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• 제13권6호
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• pp.439-450
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• 1997

Atmospheric fine particles $(PM_{2.5})$ were collected at the background sites, Kangwha, Taean, and Kosan and characterized to understand their behaviors at the sites. Daily samples of $PM_{2.5}$ mass were measured and ionic species, carbonaceous species, and gaseous species were analyzed. Four-day backward trajectory analysis was also carried out. The mean concentrations of anthropogenic species were highest at Kangwha among three sites, while contributions from sea salts wree highest at Taean during the measurement period due to higher wind speed at Taean. Major chemical components in fine particles were sulfate, organic carbon, nitrate, and ammoniu. Most of the non-sea-salt (nss) sulfates in $PM_{2.5}$ might be present as ammonium sulfates at these sites. Most air parcels arriving at Kangwha and Taean were from northern China. Therefore, both sites were thought to be affected by the same air parcel. At Kosan, during the measurement period, air parcels were from either northern China or sourthern China. The nss sulfate concentration in the air parcels from southern China was higher, while the nss calcium, nitrate, and ammonium concentrations were higher when the air parcels were from northern China.

• 한국농공학회논문집
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• 제54권2호
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• pp.55-65
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• 2012

In the winter season, when the ventilation system is operating, the fresh cold air from the slot-type openings of broiler house which directly reached the animal zone can cause various problems such as thermal stress, decreasing of feed and water consumption, occurrence of respiratory disease, and etc. Therefore it is very important to control the trajectory of aero-flow from the slot openings to induce an efficient thermal heat change. Jet-drop distance model was proposed to predict and control the jet-trajectory. However their study was restricted due to the small scaled model and difficulties of measuring the Jet-drop distance. In this study, CFD was applied to analyze qualitatively and quantitatively the jet-drop distance in a real broiler house. The various variables were considered such as installed slot-angle, designed ventilation rate, and the outdoor ambient temperature. From the present study, two linear-regression models using the Jet-drop factor and corrected Archimedes number, and their R-squared values 0.744 and 0.736, respectively, were used. From this study, the applicability of CFD on the analysis of Jet-drop distance model was confirmed.

• Journal of Astronomy and Space Sciences
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• 제35권3호
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• pp.119-131
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• 2018

In spite of a short history of only 30 years in space development, Korea has achieved outstanding space development capabilities, and became the $11^{th}$ member of the "Space Club" in 2013 by launching its own satellites with its own launch vehicle from a local space center. With the successful development and operation of more than 10 earth-orbiting satellites since 1999, Korea is now rapidly expanding its own aspirations to outer space exploration. Unlike earth-orbiting missions, planetary missions are more demanding of well-rounded technological capabilities, specifically trajectory design, analysis, and navigation. Because of the importance of relevant technologies, the Korean astronautical society devoted significant efforts to secure these basic technologies from the early 2000s. This paper revisits the numerous efforts conducted to date, specifically regarding flight dynamics and navigation technology, to prepare for future upcoming planetary missions in Korea. However, sustained efforts are still required to realize such challenging planetary missions, and efforts to date will significantly advance the relevant Korean technological capabilities.