• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.262-269
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• 2002

The purpose of this study was to compare the effect of distance of light tip to resin surfaces and exposure time on the polymerization of surface and 2 mm subsurface of composite resins cured with two light sources; conventional halogen light (XL 3000, 3M, U.S.A.) and plasma arc light (Flipo, LOKKI, France) and compare the uniformity of polymerization from the center to the periphery of resin surfaces according to polymerization diameter cure with two light sources. From the experiment, the following results were obtained. 1. Difference of relative light intensity decrease in plasma arc light smaller than that of conventional halogen light(p<0.05). 2. In all groups, microhardness of top surfaces was decreased when distance of the light tip to resin surfaces is more than 2mm and increased according to increase of exposure time(p<0.05). 3. Difference of microhardness of the 2mm subsurface was rapidly decreased when distance of light tip to resin surfaces is more than 4mm(except, plasma arc light exposure time of 3 seconds). and the distance of light tip to resin surfaces and exposure time more affected 2mm subsurface rather than top surface(p<0.05). 4. Although exposure time was increased, difference of microhardness of the 2mm subsurface with the distance of light tip to resin surfaces was relatively high in groups between below 4mm and 6 mm(p<0.05). 5. Plasma arc light exposure time of 6 to 9 seconds produced microhardness values and microhardness change according to various distance similar to those produced with 40 to 80 second exposure to a conventional halogen light(p>0.05). 6. In all groups, microhardness was decreased gradually from the center to the periphery of resin surfaces(p<0.05).

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.434-440
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• 2022

The ICAO (International civil aviation organization)recommended the implementation of the GANP (global air navigation plan) for strategic decision-making and air traffic management evaluation. In this study, we proposed a new method for finding the route distance from KPI (key performance indicator) 05 actual route extension presented for air traffic management evaluation. For this purpose, we collected trajectory data for one month and calculated the en-route distances using the methods presented in ICAO and the methods presented by this author. In the ICAO method, the intersection point must be estimated through the equation of a circle for radius 40 NM and the equation of a straight line for an inner and outer point close to a circle in the track data, and four flight distances are calculated to calculate the en-route distance. In the method presented in this study, two flight distances are calculated without estimating the intersection point to calculate the en-route distance. To determine the error between the two methods, we used the performance evaluation index RMSE (root mean square error) and the determination factor R² of the regression model.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.1-8
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• 2005

Plasma researches using parallel-plate electrodes are widely used in semiconductor application such as etching and thin film deposition. Therefore, a quantitative understanding and control of plasma behavior are becoming increasingly necessary because their important applications and simulation techniques have been actively carried out in order to solve such problems above. In this paper, we developed a two-dimensional(2D) self-consistent fluid model, because 2D models can deal with real reactor geometries. The fluid model is based on particle continuity equations for taking account of an electrode system in a cylindrical geometry. An pure Ar gas was used at 500[mTorr] and radio-frequency (13.56(MHz)). Four models were simulated under the different electrode geometries which have chamber widths of 5.25, 6.0, 8.0, and 10.0[cm] and we compared their results with each other. Plasma uniformity and a do self-bias voltage were also discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1183-1189
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• 2015

This study focuses on the design of the tapered joints of a wind power turbine. The main variables of the tapered joint are the transmitted torque, shaft diameter, contact area of the tapered ring, and tightening torque of the bolts, which applies a compressive pressure from the hub to the shaft. The stress distribution of the taper fit was calculated under axisymmetric plane strain conditions because of the small taper angle. The axial displacement of the clamp can be calculated from the radial elastic deformation and the taper angle. The stress field of each ring is obtained from the cylinder stress equation. To verify the accuracy of the calculation, finite element (FE) analysis was performed, and the results of the calculation and FE analysis were compared. The hoop stress of the tapered surface showed a discrepancy of approximately 10, but the trends of the stress distributions of each component and the relative movement obtained by FE analysis were in good agreement with the analytical calculation results.

• Water for future
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• v.27 no.3
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• pp.115-121
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• 1994

Cohesie sediment movement in estuarine systems is strongly affected by the phenomena of aggregation and flocculation. Aggregation is the process where primary particles are clustered together in tightly-packed formations; flocculation is the process where aggregates and single particles are bonded together to form large particle groups of very low specific density. The size, shape and strength of the flocculants control the rate of deposition and the processes of pollutant exchange between suspended sediments and ambient water. In estuarine waters, suspended sediments above the lutocline form the mobile suspension zone while below the lutocline they form the stationary suspension zone. Suspended particles in the mobile zone are generally in a dispersed state and the controlling forces are the Brownian motion and the turbulent flow fluctuations. In the stationary suspension zone, the driving force is the gravity. This paper discusses the settling and particle flocculation characteristics under quiescient flow conditions. Particles are entering the study domain randomly. Particles in the mobile suspension zone are simulated by using the Smoluchowski's model. Flocs created in the mobil suspension zone are moving into the stationary suspension zone where viscosity and drag effects are important. Utilizing the concepts of the maximum Feret's diameter and the Minkowski's sausage logic, the fractal dimension of the flocs within the stationary suspension is estimated and then compared with results obtained by other studies.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.352-360
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• 2019

This paper proposes a docking assessment algorithm for an autonomous underwater vehicles (AUVs) with sensor uncertainties. The proposed algorithm consists of two assessments, state assessment and probability assessment. The state assessment verifies the reachability by comparing forward distance to the docking station with expected distance to reach same depth as the docking station and necessity for correcting its route by comparing calculated inaccessible areas based on turning radius of the AUV to position of the docking station. When the AUV and the docking station is close enough and the state assessment is satisfied, the probability assessment is conducted by computing success probability of docking based on the direction angle, relative position to the docking station, and sensor uncertainties of the AUV. The final output of the algorithm is decided by comparing the success probability to threshold whether to try docking or to correct its route. To verify the validation of the suggested algorithm, the scenario that the AUV approaches to the docking station is implemented through Matlab simulation.

• Journal of the Korean Society for Railway
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• v.11 no.5
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• pp.504-512
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• 2008

In general, based on criteria of subway law, radius 500m from subway station is defined as SIA (Subway Station Influence Area). Therefore, in this paper, selection models of SIA are developed to identify appropriate SIA for specific legions in Seoul metropolitan city based on CHAID analysis. As a result, following outputs are obtained; (1) walking distance from subway station is the most influential factor to define SIA (2) SIAs vary with regions (i. e. Gangnam area: 767m, Gangbuk area: 452m), and (3) walking distance from subway station is influential to land price of SIA. In addition, in Gangnam, the structure of land price of the closest section has a polynomial trend curve rather than linear compared in comparison with other sections. Therefore, it is desirable for current definition of SIA (radius 500m from subway station) to be redefined to reflect characteristics of land use and walking distance according to each region respectively.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.304-309
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• 2008

본 논문은 기존 기발된 재실자의 탈출 계획 및 예측 프로그램 개발에 대해 길 찾기를 위한 알고리즘으로는 Dijkstra 알고리즘, Best-First Search 알고리즘, Johnson 알고리즘 등이 있으며 가장 안정적으로 알고리즘 구현이 가능한 A*알고리즘을 적용하였다. 따라서, 본 개발 프로그램은 재실자가 대피 목적지를 향한 최적의 길 찾기를 이용하여 가장 가까운 거리에 있는 탈출구를 효율적으로 찾을 수가 있으며 재실자의 사실감 있는 대피 이동 동선의 구현을 위해 기존의 경직된 경로를 매끄럽게 구현하였다. 탈출구는 흐름율과 정체 반경을 적용하여 재실자가 탈출구에 밀집하였을 경우 병목 현상이 발생하도록 하여 대피현상이 실제 상황과 유사하도록 프로그램을 구축하였다. 본 대피프로그램은 실제 건물의 CAD도면을 import 가능하도록 구축함으로서 대피평가시간을 절약할 수 있도록 하였다.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.353-358
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• 2006

지자체에 보유하고 있는 문화유적에 대한 현황이 표시된 종이도면에 대해 스캐닝을 통한 벡터라이징을 수행하여 자료를 전산화하고 지적도와 중첩 표시 되어있는 현황에 맞게 동일좌표계로 데이터를 구축한다. 이러한 기초데이터에 대해 사용자의 질의 및 이에 의한 검색을 수행하기 위해 개발도구는 Visual C++, Visual Basic과 지도에 대한 질의 및 화면도시를 위한 기초엔진을 Map Object를 통해 최적화 시켰다. 본 연구를 통해 구축된 시스템의 중요기능으로는 문화유적에 대해 지번 및 반경입력을 통해 유적에 영향을 미치는 영향권 분석, 선택지번에서 최단거리에 있는 문화재 검색, 최단경로 분석, 문화재에 대한 다양한 정보 및 관리대장에 대한 관리기능 등의 주요기능이며 부수적으로 다양한 검색 및 출력을 위해 지번 및 소유자검색, 대장검색, 문화재검색, 도면 및 대장출력, 출력물 연동, 화면이미지 저장 등을 수행하도록 시스템을 구축하였다.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.373-375
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• 2003

상반회전 풍력발전 시스템의 경우 전방에 위치한 로터의 후류 효과를 적절히 반영하여 설계에 이용해야 한다. 본 연구에서는 이러한 로터의 후류효과 및 블레이드의 실속후 모델을 고려하여 30kW급 상반회전시스템의 설계형상에 대한 검토연구를 수행하였다 기본공력이론은 모멘텀 이론과 2차원 준정상 공기력 이론을 통합한 형태를 사용하였다. 로터의 후류영향을 고려하기 위해 축소형 풍차 블레이드 모델에 대한 풍동시험 결과를 적절히 이용하며, 이로부터 보조로터를 지난 후류의 축속도 및 각속도 성분을 결정하였다. 최종적으로 상반회전 시스템의 로터 반경 및 상호 이격거리 등을 고려한 성능해석을 수행하고 이로부터 최적 설계형상에 대한 파라미터 연구결과를 제시하였다.