• 제목/요약/키워드: Li-Hak

검색결과 184건 처리시간 0.022초

도로 거칠기와 차량의 승객 상태를 활용한 DSJS(Driving Situation Judgment System) 설계 (The Driving Situation Judgment System(DSJS) using road roughness and vehicle passenger conditions)

  • 손수락;정이나;안희학
    • 한국정보전자통신기술학회논문지
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    • 제14권3호
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    • pp.223-230
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    • 2021
  • 현재 자율주행차량은 테스트 이후 상용화를 눈앞에 두고 있다. 그러나 아직 자율주행차량이 완벽히 상용화되지 않았음에도 81건의 사고가 발생했으며, 사고를 피하기 위한 차량의 주행 방식은 LiDAR에 많이 의존하고 있다. 현재 상용화된 3레벨 자율주행차량이 4레벨 자율주행차량으로 발전하기 위해서는 기존에 수집되는 정보보다 더 많은 정보를 수집해야만 한다. 따라서 본 논문에서는 기존의 자율주행차량에서 수집하는 정보인 도로 정보, 기상정보를 포함하여 차량이 주행 중인 도로의 거칠기와 자기 자신 및 주변 차량의 탑승객 상태를 정확하게 인식하여 차량이 처한 위기 상황을 정확하게 계산하는 Driving Situation Judgment System (DSJS)을 제안한다. DSJS의 PDM에 대한 실험 결과, PDM은 기존 차량의 탑승객 인식 시스템보다 평균적으로 15.52% 더 정확하게 탑승객을 분류할 수 있었다. 본 연구는 기존 3단계 자율주행차량이 수집하는 데이터보다 더 다양한 종류를 수집하여 4단계 자율주행차량을 달성하는 기초연구가 될 수 있다.

초음파센서를 활용한 토양침식모니터링 방법 개발 (I) (Development of a Monitoring Method for Soil Erosion using an Ultrasonic Sensor (I))

  • 남경훈;이재형;이학윤;정교철
    • 지질공학
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    • 제25권1호
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    • pp.83-91
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    • 2015
  • 기후변화에 따른 대규모 토양유실에 대한 토양관리 및 적절한 대책이 수립되어야 하나 현재까지 토양침식 실측자료 및 정책을 뒷받침할 연구가 전무한 실정이다. 이에 본 연구는 유역규모에서 토양침식의 정량적 분석을 위하여 실시간 측정 장치인 스마트센서를 개발하였고 실제 지형을 정밀하게 표현하는 지상라이다를 활용하여 비교 및 검증하였다. 스마트 센서는 초음파센서, 강우계, 태양열전지, RTU 및 CDMA 무선통신망 등으로 구성하였고 30분 간격으로 토양침식변위를 정량적으로 파악할 수 있게 하였다. 연구결과 2013년 8월 22일부터 10월 11까지 측정된 라이다와 초음파센서의 토양침식깊이의 상관관계는 0.9182이었다. 또한 라이다의 토양침식깊이(mm)와 토양침식량(m3)의 상관관계는 하부 영역에서 0.9063, 상부영역에서 0.9868이었다. 향후 스마트센서의 추가자료 확보, 설치 위치 최적화 및 자료 보정이 수행되어 유역규모에 설치된다면 토양보전 및 관리 체계의 기초자료로 양질의 자료를 제공하리라 판단된다.

Mobile Mapping System Point Cloud를 활용한 도로주변 시설물 DB 구축 및 위치 정확도 평가 (Evaluating a Positioning Accuracy of Roadside Facilities DB Constructed from Mobile Mapping System Point Cloud)

  • 김재학;이홍술;노수래;이동하
    • 한국지리정보학회지
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    • 제22권3호
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    • pp.99-106
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    • 2019
  • 최근 자율주행 분야가 4차 산업혁명 시대에 맞이하여 주요한 기술분야로 각광받고 있다. 자율주행 분야는 4차 산업의 핵심 기술의 집합체라고 볼 수 있는데, 이 중 자율주행 지원을 위한 정밀도로 지도 및 도로시설물 구축을 위한 DB 분야가 필수적인 부분이다. 기존 2차원 자료형식으로 제작되고 관리되던 지도 DB가 3차원으로 급격히 변화하고 있으며, 더불어 이러한 정밀도로 지도를 구축을 위한 핵심기술로 Mobile Mapping System(MMS)가 활발히 이용되고 있다. 특히 MSS에서 획득되는 다양한 자료 중에서 LiDAR를 통해 취득되는 정밀 Point Cloud는 정확한 위치 정보를 포함하고 있어, 정밀도로 지도 구축 및 도로시설물 관리 등을 위한 다양한 관련 DB 구축에 활용되고 있다. 하지만 현재는 정밀도로 지도 제작 시 3D 모델링을 위한 기반 데이터로만 활용되는 것으로만 국한되어 그 사용 범위가 넓지 않은 문제가 있다. 본 연구에서는 MMS 취득자료의 활용성을 높이기 위하여 MMS LiDAR Point Cloud를 활용하여 도로 주변 시설물을 추출하고, 그 위치를 현장조사 성과와 중첩하여 비교 분석하여 그 위치 정확도에 기준한 도로시설물 분야 활용성을 확인하고자 하였다. Point Cloud로부터 전신주와 통신지주 DB를 구축하고 도로명주소기본도와 위치 비교를 수행한 결과, Point Cloud에서 추출한 시설물 DB의 위치 정확도는 도로명주소기본도 보다 높은 것으로 확인되었다. 이를 통해 MMS Point Cloud 자료를 도로시설물 관리 분야에 충분히 활용하는 것이 가능하며, 추후 이를 통해 도로시설물 지도 확대 구축하고, 도로대장 관리 등에 적용하는 연구가 필요 할 것으로 판단된다.

영산강 수계 표층 퇴적물의 금속류 분포 및 오염도 평가 (Assessment of Heavy Metal Pollution in Surface Sediments of the Yeongsan River)

  • 양해종;강태우;봉기문;정효진;양원준;한종학;정희정;황순홍;김경현
    • 환경분석과 독성보건
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    • 제21권4호
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    • pp.292-303
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    • 2018
  • The particle sizes and heavy metal concentrations (Pb, Zn, Cu, Cd, Hg, As, Cr, Ni, Li, Al) of surface sediments of the Yeongsan River were analyzed to assess the distribution and pollution level of heavy metals. The distribution of particle sizes was dominated by sand in the upstream sites (MS1-MS7) and by silt loam in the downstream sites (MS8-ML3), but MS3 and MS6, located slightly upstream of the two weirs, were found to be loamy sand and silt loam, respectively. The concentrations of Pb, Zn, Cu, Cd and Hg were higher at the upstream sites, while As, Cr, Ni and Li were higher at the downstream sites. The heavy metals of crustal origin (As, Cr, Ni and Li) were strongly correlated with particle size, while the other heavy metals (Pb, Zn, Cu, Cd and Hg) were weakly correlated with particle size. Considering their concentrations, most of heavy metals were evaluated as having almost no toxic effects on benthic organisms, at all sites. In addition, anthropogenic contamination by the $I_{geo}$, EF and CF were found to have no impact at most sites, with only low levels of pollution at the others. Using the PLI method, the MS2 and MS3 sites, located upstream, were assessed to be affected by anthropogenic contamination. Most importantly, Zn, Cu and Hg were found to be the elements responsible for most pollution, and they were highest at the upstream sites, implying pollution by domestic sewage and urban discharge.

Accuracy of artificial intelligence-assisted landmark identification in serial lateral cephalograms of Class III patients who underwent orthodontic treatment and two-jaw orthognathic surgery

  • Hong, Mihee;Kim, Inhwan;Cho, Jin-Hyoung;Kang, Kyung-Hwa;Kim, Minji;Kim, Su-Jung;Kim, Yoon-Ji;Sung, Sang-Jin;Kim, Young Ho;Lim, Sung-Hoon;Kim, Namkug;Baek, Seung-Hak
    • 대한치과교정학회지
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    • 제52권4호
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    • pp.287-297
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    • 2022
  • Objective: To investigate the pattern of accuracy change in artificial intelligence-assisted landmark identification (LI) using a convolutional neural network (CNN) algorithm in serial lateral cephalograms (Lat-cephs) of Class III (C-III) patients who underwent two-jaw orthognathic surgery. Methods: A total of 3,188 Lat-cephs of C-III patients were allocated into the training and validation sets (3,004 Lat-cephs of 751 patients) and test set (184 Lat-cephs of 46 patients; subdivided into the genioplasty and non-genioplasty groups, n = 23 per group) for LI. Each C-III patient in the test set had four Lat-cephs: initial (T0), pre-surgery (T1, presence of orthodontic brackets [OBs]), post-surgery (T2, presence of OBs and surgical plates and screws [S-PS]), and debonding (T3, presence of S-PS and fixed retainers [FR]). After mean errors of 20 landmarks between human gold standard and the CNN model were calculated, statistical analysis was performed. Results: The total mean error was 1.17 mm without significant difference among the four time-points (T0, 1.20 mm; T1, 1.14 mm; T2, 1.18 mm; T3, 1.15 mm). In comparison of two time-points ([T0, T1] vs. [T2, T3]), ANS, A point, and B point showed an increase in error (p < 0.01, 0.05, 0.01, respectively), while Mx6D and Md6D showeda decrease in error (all p < 0.01). No difference in errors existed at B point, Pogonion, Menton, Md1C, and Md1R between the genioplasty and non-genioplasty groups. Conclusions: The CNN model can be used for LI in serial Lat-cephs despite the presence of OB, S-PS, FR, genioplasty, and bone remodeling.

Effects of sodium diacetate or microbial inoculants on aerobic stability of wilted rye silage

  • Li, Yan Fen;Wang, Li Li;Jeong, Eun Chan;Kim, Hak Jin;Ahmadi, Farhad;Kim, Jong Geun
    • Animal Bioscience
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    • 제35권12호
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    • pp.1871-1880
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    • 2022
  • Objective: The primary goal was to identify the effectiveness of chemical or biological additives in delaying the deterioration of early-harvested wilted rye silage after exposure to air. Methods: Rye harvested as a whole plant at the early heading stage was wilted for 24 h. The wilted forage was divided into treatments including sodium diacetate (SDA) at 3 (SDA3) and 6 g/kg (SDA6), Lactobacillus plantarum (LP), L. buchneri (LB), or their equal mixture (LP+LB) at 1×106 colony-forming unit/g fresh matter. Results: After 60 d of conservation in 20-L silos, lactic acid was greater in LP and LP+LB silages than other treatments (102 vs 90.2 g/kg dry matter [DM]). Acetic acid was greatest in SDA6 (32.0 g/kg DM) followed by LB (26.1 g/kg DM) and was lowest in LP treatment (4.73 g/kg DM). Silage pH was lower with microbial inoculation and the lowest and highest values were observed in LP and untreated silages, respectively. After 60 d, neutral detergent fiber concentration was lowest in SDA6 silages, resulting in the greatest in vitro DM digestibility (846 g/kg DM). Aerobic stability was longest in SDA6 (176 h) followed by LB treatment (134 h). Instability after aerobiosis was greatest in LP silages (68 h), about 8 h less than untreated silages. After aerobic exposure, yeast and mold numbers were lowest in SDA6 silages, resulting in DM loss minimization. Exhaustion of acetic acid and lactic acid after aerobic exposure was lowest with SDA6 but greatest with untreated and LP silages. Conclusion: Treatment of early-cut wilted rye forage with SDA at 6 g/kg resulted in silages with higher feeding value and fermentation quality, and substantially delayed deterioration after aerobic exposure, potentially qualifying SDA at this load for promotion of silage quality and delaying aerobic spoilage of early-harvested (low DM) rye forage.

Biomass Expansion Factors for Pinus koraiensis Forests in Korea

  • Li, Xiaodong;Yi, Myong-Jong;Jeong, Mi-Jeong;Son, Yo-Whan;Park, Pil-Sun;Lee, Kyeong-Hak;Son, Yeong-Mo;Kim, Rae-Hyun
    • 한국산림과학회지
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    • 제99권5호
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    • pp.693-697
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    • 2010
  • Biomass expansion factors that convert the timber volume (or dry weight) to biomass are used to estimate the forest biomass and account for the carbon budget on a national and regional scale. This study estimated the biomass conversion and expansion factors (BCEF), root to shoot ratio (R), biomass expansion factors (BEF) and ecosystem biomass expansion factor (EBEF) of Korean pine (Pinus koraiensis) forests based on direct field surveys and publications in Korea. The mean BCEF, BEF, and R was 0.6438 Mg $m^{-3}$ (n = 7, SD = 0.1286), 1.6380 (n = 27, SD = 0.1830), and 0.2653 (n = 14, SD = 0.0698), respectively. The mean EBEF, which is a simple method for estimating the understory biomass in Korean pine forest ecosystems, was 1.0218 (n = 6, SD = 0.0090). The values of the biomass expansion factors in this study estimated the Korean pine forest biomass with more precision than the default values given by the IPCC (2003, 2006).

Numerical investigation on effects of rotor control strategy and wind data on optimal wind turbine blade shape

  • Yi, Jin-Hak;Yoon, Gil-Lim;Li, Ye
    • Wind and Structures
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    • 제18권2호
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    • pp.195-213
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    • 2014
  • Recently, the horizontal axis rotor performance optimizer (HARP_Opt) tool was developed in the National Renewable Energy Laboratory, USA. This innovative tool is becoming more popular in the wind turbine industry and in the field of academic research. HARP_Optwas developed on the basis of two fundamental modules, namely, WT_Perf, a performance evaluator computer code using the blade element momentum theory; and a genetic algorithm module, which is used as an optimizer. A pattern search algorithm was more recently incorporated to enhance the optimization capability, especially the calculation time and consistency of the solutions. The blade optimization is an aspect that is highly dependent on experience and requires significant consideration on rotor control strategies, wind data, and generator type. In this study, the effects of rotor control strategies including fixed speed and fixed pitch, variable speed and fixed pitch, fixed speed and variable pitch, and variable speed and variable pitch algorithms on optimal blade shapes and rotor performance are investigated using optimized blade designs. The effects of environmental wind data and the objective functions used for optimization are also quantitatively evaluated using the HARP_Opt tool. Performance indices such as annual energy production, thrust, torque, and roof-flap moment forces are compared.

The Effect of Hydrogen Peroxide Bleaching on the Properties of Hardwood Kraft Pulp Absorbed with Birchwood Xylan

  • ;이상훈;이학래
    • 한국펄프종이공학회:학술대회논문집
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    • 한국펄프종이공학회 2010년도 춘계학술발표회 논문집
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    • pp.195-206
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    • 2010
  • Xylan can be applied to improve the strength properties of paper; however the optical properties, such as brightness, are decreased significantly. To solve that problem, an applicable bleaching process is therefore desired. The aim of this research was to investigate the impact of hydrogen peroxide bleaching on hardwood kraft pulp pretreated with birchwood xylan by measuring optical properties (whiteness, brightness, opacity) as well as physical properties (tensile index, tearing index, bulk) of handsheets made from the bleached pulp. Hydrogen peroxide bleaching, as a kind of totally chlorine free (TCF) bleaching method, is quite important industrially for chemical pulp. In our work, the process variables of peroxide bleaching including bleaching temperature, time, initial pH and $MgSO_4$ dosage were studied. The results showed that both good mechanical properties and optical properties could be achieved when the operating parameters were controlled properly and therefore hydrogen peroxide bleaching was proved to be a suitable method for bleaching hardwood kraft pulp with adsorption of birchwood xylan.

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인접하는 수치지도 간의 경계영역 불일치 보정 (Correcting Inconsistency on the Boundary of Neighboring Maps)

  • 김원태;김학철;이기준;안병익;김성룡
    • 대한공간정보학회지
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    • 제7권1호
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    • pp.41-52
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    • 1999
  • 인접하는 수치지도 경계상의 불일치 문제를 해결하기 위해서 중간선 방법이 광범위하게 사용되어 왔다. 하지만, 이 방법은 인접하는 경계선 주위의 객체에 대해서 위상정보의 일관성을 상실하거나 정확도의 저하를 초래할 수 있다 본 논문에서는 이러한 중간선 방법의 문제점을 해결하기 위해서 두 가지 에지 메칭 방법을 제시한다 첫 번째 방법은 경계선 주위에 위치하고 있는 객체에 대해서 신축적으로 변환하는 러버쉬팅에 기초한 방법이다. 두 번째 방법은 경계선으로부터의 거리 함수를 이용하여 객체들의 기하적인 정보를 변환한다. 이러한 방법들은 이전의 방법에 비해서 위상정보를 유지하고 정확도를 향상시키는 장점이 있다.

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