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항공 LiDAR 자료를 이용한 산림재적추정 모델 개발 - 봉화군 춘양면 애당리 혼효림을 대상으로 -
조승완,김용구,박주원,CHO, Seung-Wan,KIM, Yong-Ku,PARK, Joo-Won 한국지리정보학회 2017 한국지리정보학회지 Vol.20 No.3
본 연구의 목적은 산림재적 현장자료와 항공 LiDAR 자료 기반의 산림재적 추정을 위한 회귀모델의 개발이다. 추정 모델은 경상북도 봉화군 지역에서 임의추출법에 의해 선정된 30개의 원형 표본지로부터 산출한 표본지별 산림재적을 반응변수로 하고, 항공 LiDAR 원자료로부터 개별 표본지의 고도분포 백분위수(Height Percentiles, HP) 및 층위 단위 점 개체수 백분율(Height Bin, HB)을 추출하여 예측변수로 사용하여 구성하였다. 단순선형회귀분석, 이차 다항회귀분석 및 단계적 회귀분석 방법을 이용한 다중회귀분석을 실시하여 적합모델들의 후보들을 도출하였으며, 검증을 위하여 각 모델별로 교차 타당성 검증을 실시하여 PRESS 통계치를 구하였다. 모델의 $R^2$ 및 PRESS을 비교하여 적합성을 검토한 결과, $HB_{5-10}$, $HB_{15-20}$, $HB_{20-25}$, $HBgt_{25}$의 다중회귀모델의 $R^2$이 0.509로 가장 높고, $HP_{25}$ 단순회귀모델의 PRESS 값이 122.352으로 가장 낮은 것으로 나타났다. 수직구조가 복잡한 우리나라 산림재적을 추정하는 모델로는 다양한 수직적 정보를 포함하고 있는 $HB_{5-10}$, $HB_{15-20}$, $HB_{20-25}$, $HBgt_{25}$이 상대적으로 보다 적합하다고 사료된다. This study aims to develop a regression model for forest volume estimation using field-collected forest inventory information and airborne LiDAR data. The response variable of the model is forest stem volume, was measured by random sampling from each individual plot of the 30 circular sample plots collected in Bonghwa-gun, Gyeong sangbuk-do, while the predictor variables for the model are Height Percentiles(HP) and Height Bin(HB), which are metrics extracted from raw LiDAR data. In order to find the most appropriate model, the candidate models are constructed from simple linear regression, quadratic polynomial regression and multiple regression analysis and the cross-validation tests were conducted for verification purposes. As a result, $R^2$ of the multiple regression models of $HB_{5-10}$, $HB_{15-20}$, $HB_{20-25}$, and $HBgt_{25}$ among the estimated models was the highest at 0.509, and the PRESS statistic of the simple linear regression model of $HP_{25}$ was the lowest at 122.352. $HB_{5-10}$, $HB_{15-20}$, $HB_{20-25}$, and $HBgt_{25}-based$ models, thus, are comparatively considered more appropriate for Korean forests with complicated vertical structures.
조승완(Seung-Wan Cho),김규보(Guy-Bo Kim),최승환(Seung-Hwan Choi),전충환(Chung-Hwan Jeon),장영준(Young-June Chang) 한국자동차공학회 2002 한국자동차공학회 지부 학술대회 논문집 Vol.2002 No.10
A cylindrical C.V.C.C. was used to investigate the combustion characteristics of methane-air mixture under three initial pressure conditions and four excess air ratios. Combustion pressure development was measured by piezoelectric pressure transducer to investigate the characteristics of combustion in quiescent mixture. Obtained results are as follows. The maximum combustion pressure depended on the effect of the initial pressure of combustion chamber and on the excess air ratio of mixture. The ratio of initial combustion duration to total combustion duration was inverse proportion to initial charge pressure of C.V.C.C.<br/>
대단위 산림경영계획수립을 위한 GIS 기법 적용에 관한 연구; 금강소나무 경영단지의 구역설정사례를 중심으로
조승완 ( Seung Wan Cho ),주성현 ( Sung Hyun Joo ),한상열 ( Sang Yoel Han ),김동근 ( Dong Geun Kim ),김의경 ( Eui Gyeong Kim ),박주원 ( Joo Won Park ) 한국임학회 2014 산림과학 공동학술대회 논문집 Vol.2014 No.-
대면적 산림경영의 경우 임상의 특성에 따라 구역을 합리적으로 설정하고 각 구역별 특성에 맞는 장기경영기본계획을 수립할 필요가 있다. 대면적 산림을 구역 설정함에 있어서 지리정보체계를 활용하는 것이 유용하다고 알려졌으나 우리나라에서 실증적으로 이루어진 사례는 찾기 힘들었다. 따라서 본 연구는 경상북도 울진·봉화지역의 약 15,000 ha 규모의 금강소나무 경영단지에 대한 기본계획을 수립하는데 필요한 구역을 설정하는 지리정보체계를 적용하는 방법에 대한 것으로서 이를 통해 지리정보체계의 적용가능성 및 제한점을 파악하고자 하였다. FGIS의 수치임상도 및 산림입지도를 기반으로 소나무림 적지조건과 기존 소나무림과의 접근성 등의 조건을 이용하여 5개의 구역을 분류하였다. 경영단지구역을 구획한 결과, 금강소나무 핵심보전구역이 32%, 버퍼 내 중점시업구역이 6.1%, 버퍼 내 완충구역이 20.2%, 버퍼 외 중점시업구역이 7.6%, 그 외 완충구역이 34.1%로 나타났다. 본 연구결과 FGIS 자료를 활용한 지리정보체계는 대면적 산림경영의 기본계획 수립에 적용 가능한 것으로 판단된다. Large-scale forest management requires reasonable zoning in consideration of the characteristics of each individual forest stands and, ultimately, the establishment of the long-term master plan based on the distinguished zones. For zoning large-scale forests, Geographic Information Systems(GIS) is known to be useful but any practices have not been reported in S. Korea. Thus, this study aims to contribute to understanding the feasibility and the limitation of the GIS application to large-scale forest management by applying the GIS to zoning the Kumgangsong ( Pinus densiflora for. erecta U) management complex which covers approximately 15,000 ha across two counties in Gyeongsangbuk-do: Bonghwa and Uljin. Based on the FGIS data, the algorithm is developed to classify five major zones according to the suitable-site conditions for the Kumgangsong as well as the proximity to the existing the Kumgangsong stands. As a result of the zoning, the core preservation zone makes up 32% of the total complex area. The main operational zone in and out of the buffer covers 6.1 % and 7.6%, respectively. Finally, the neutral zone in and out of the buffer consists of 20.2% and 34.1%, respectively. In conclusion, the GIS analysis using FGIS is found to be feasible in establishing a master plan for large-scale forest management.
정적연소기에서 메탄-공기 혼합기의 균질연소 및 배기배출물 특성
조승완(Seung-wan Cho),최승환(Seung-hwan Choi),곽철우(Chul-woo Kwark),전충환(Chung-whan Jeon),장영준(Gyoung-juen Chang) 한국자동차공학회 2003 한국자동차공학회 지부 학술대회 논문집 Vol.2003 No.10
A Cylindrical constant volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of a homogeneous charge methane-air mixture under various overall charge pressures, excess air ratios and ignition times. The !low characteristics, including the mean velocity and turbulence intensity, were analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer, a flame propagation image acquired by ICCD camera and exhaust emissions measured by 2-valve gas chromatography were used to investigate the effects of initial pressures, excess air ratios and ignition times on the combustion characteristics.<br/> It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to a near-zero value after 3000 ms, and that the combustion duration, !lame speed and burning velocity had good characteristics under the conditions of an excess air ratio of 1.1, an overall charge pressure of 0.15 MPa and an ignition time of 300 ms in the present study. And the CO₂concentration was proportional to the ignition time and overall charge pressure, the O₂concentration was proportional to the excess air ratio, and the UHC concentration was inversely proportional to the ignition time and overall charge pressure.
조승완(Seung Wan Cho),김규보(Guy Bo kim),최승환(Seung Hwan Choi),전충환(Chung Hwan Jeon),장영준(Young June Chang) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
A cylindrical C.V.C.C was used to investigate the combustion characteristics of methane-air mixture under various initial pressure conditions and excess air ratios. Combustion pressure duvelopment was measured by piezoelectric pressure transducer to investigate the characteristics of combustion in quiescent mixture. Obtained results are as follows. The maximum pressure of combustion depended on the effect of the initial pressure of combustion chamber and on the lean level of mixture. The ratio of initial combustion duration to total combustion duration was inverse proportion to initial charge pressure of C.V.C.C.
스로틀 바디가 가솔린 엔진의 출력 및 배기배출물 특성에 미치는 영향에 관한 실험적 연구
조승완(Seung Wan Cho),이상석(Sang Suk Lee),진동규(Dong Kyu Jin),심재준(Jae Joon Shim),김규보(Gyu Bo Kim),전충환(Chung Hwan Jeon),장영준(Young June Chang) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.11
Many researches have been carried out to reduce the emission levels and lower the fuel consumption in SI engines. Recently electronically controlled injection system is widely adapted to a passenger car to achieve these goals. Throttle body is also an important factor which influences on the emissions and engine power. In this study we redesigned a throttle body and conducted an experimental study to see the effects on engine performance and emission characteristics. We could find that idle speed control(ISC) showed stable operation characteristics as the cooling water temperature varied. And CO and HC emissions also satisfied the regulation limit.
금속 재료의 잠닉손상 평가를 위한 비선형 전자기음향공진 기법에 관한 연구
조승완(Seung-Wan Cho),조승현(Seung-Hyun Cho),박춘수(Choon-Su Park),서대철(Dae-Cheol Seo),장경영(Kyung-Young Jhang) 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.4
최근 전통적 초음파기법이 탐상할 수 없는 잠닉손상을 평가할 수 있는 잠재적 기술로서 비선형 초음파기법들에 대한 많은 관심이 있다. 비선형 초음파기법중 하나인 공진주파수 변화를 이용하는 기법은 재료의 탄성영역에서의 이력에 근거한 기술이다. 공진주파수의 변화량이 아주 작기 때문에 정교한 공진주파수 측정장치가 필요하다. 본 연구에서는 비선형 전자기음향공진기법을 적용하였다. 비선형 전자기음향공진기법은 비접촉 EMAT 센서를 사용하기 때문에 재료의 주파수 응답에 영향을 최소화할 수 있다. 3점 굽힘 피로시험을 한 알루미늄판 시편에 횡파 EMAT으로 실험을 실시하였다. 전압을 여러 레벨로 인가하며 공진을 발생시켜 잠닉손상측정에 중요한 요인중 하나인 이력 비선형 파라미터 ?를 공진주파수 변화로부터 산출하였다. 비손상시편과 손상시편에서의 측정된 이력 비선형 인자의 값이 서로 차이가 남을 확인하였다. Recently, much attention has been paid to nonlinear ultrasonic technology as a potential tool to assess hidden damages that cannot be detected by conventional ultrasonic testing. One nonlinear ultrasonic technique is measurement of the resonance frequency shift, which is based on the hysteresis of the material elasticity. Sophisticated measurement of resonance frequency is required, because the change in resonance frequency is usually quite small. In this investigation, the nonlinear electromagnetic acoustic resonance (NEMAR) method was employed. The NEMAR method uses noncontact electromagnetic acoustic transducers (EMATs) in order to minimize the effect of the transducer on the frequency response of the object. Aluminum plate specimens that underwent three point bending fatigue were tested with a shear wave EMAT. The hysteretic nonlinear parameter ?, a key indicator of damage, was calculated from the resonance frequency shift at several levels of input voltage. The hysteretic nonlinear parameter of a damaged sample was compared to that of an intact one, showing a difference in the values.