• Journal of Forest and Environmental Science
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• 제38권4호
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• pp.239-248
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• 2022

Forestry crane work in a forest harvester or forwarder is regarded as one of most hard work requiring a very high level of operation skill. The operator must handle two or more multi-axes joysticks simultaneously to control the multiple manipulators for maneuvering the crane-tip to its intended location. This study has been carried out to develop a crane-tip controller which can intuitively maneuver the crane-tip, resulting in improving the productivity by decreasing the technical difficulty of control as well as reducing the workload. The crane-tip controller consists of a single 2-axis joystick and a control algorithm run on microcontroller. Lab-scale forestry crane was constructed using electric cylinders. The crane-tip control algorithm has the crane-tip follow the waypoints generated on the given path considering the dead band region using LBO (Lateral Boundary Offset). A speed control gain to change the speed of relevant cylinders relatively is applied as well. By the P (Proportional) control within the control interval of 20 msec, the average error of crane-tip control on the predefined straight path turned out to be 14.5 mm in all directions. When the joystick is used the waypoints are generated in real time by the direction signal from the joystick. In this case, the average error of path control was 12.4 mm for straight up, straight forward and straight down movements successively at a certain constant speed setting. In the slant movement of crane-tip by controlling two axes of joystick simultaneously, the movement of crane-tip was controlled in the average error of 15.9 mm when the crane-tip is moved up and down while moving toward forward direction. It concluded that the crane-tip control was possible using the control algorithm developed in this study.

• 한국산림과학회지
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• 제111권2호
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• pp.287-301
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• 2022

본 연구는 기계화 목재 생산 작업에 가장 많이 활용되는 크레인 작업의 효율성을 높이기 위하여 엔드이펙터를 직관적으로 수직 또는 수평 제어할 수 있는 크레인 팁 제어방법을 제안하고 제어성능을 확인하기 위해 수행되었다. 실험 변수에 따른 제어성능을 검증하고자 전동실린더를 이용하여 실험실 규모의 크레인을 제작하고, 크레인에 대한 순기구학/역기구학 분석을 통하여 현재 크레인 팁의 위치좌표와 각 목표점에서의 조인트 각도를 출력할 수 있도록 구성하였다. 경로점을 생성하여 제어하는 방법을 이용하였고, LBO(Lateral Boundary Offset)을 이용한 불감대 영역을 설정하도록 하였다. 뱅뱅제어(Bang-bang control)을 이용하여 적정 파라미터를 선정하였고, 경로점의 개수와 LBO 반경은 평균오차와 관계가 있었으며, 실린더의 속도는 소요시간과 관계가 있는 것으로 확인되었다. 경로점의 개수가 증가, LBO 반경이 감소함에 따라 평균오차는 감소하였고, 실린더의 속도가 감소함에 따라 소요시간은 감소하였다. 비례제어를 이용하여 실린더의 속도가 매 제어주기마다 변경될 때에는 소요시간은 큰 폭으로 감소하였지만 실제 제어의 형상은 큰 범위에서 오버슈트와 언더슈트를 반복하며 제어가 이루어졌다. 따라서, 추가적으로 각각의 실린더의 속도를 상대적으로 변경할 수 있는 속도 게인을 적용하여 비례제어를 수행하였고, 10 mm 이내의 범위에서 제어가 이루어짐에 따라 20 ms의 제어주기에서 속도 게인이 적용된 비례제어만을 이용하여 크레인 팁 제어가 가능한 것으로 검증되었다.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제4권2호
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• pp.79-85
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• 2023

The Tibetan Plateau is home to the only alpine crane species, the black-necked crane (Grus nigricollis). Conservation efforts are severely hampered by a lack of knowledge on the spatial distribution and breeding habitats of this species. The ecological niche modeling framework used to predict the spatial distribution of this species, based on the maximum entropy and occurrence record data, allowed us to generate a species-specific spatial distribution map in Ladakh, Trans-Himalaya, India. The model was created by assimilating species occurrence data from 486 geographical sites with 24 topographic and bioclimatic variables. Fourteen variables helped forecast the distribution of black-necked cranes by 96.2%. The area under the curve score for the model training data was high (0.98), indicating the accuracy and predictive performance of the model. Of the total study area, the areas with high and moderate habitat suitability for black-necked cranes were anticipated to be 8,156 km² and 6,759 km², respectively. The area with high habitat suitability within the protected areas was 5,335 km². The spatial distribution predicted using our model showed that the majority of speculated conservation areas bordered the existing protected areas of the Changthang Wildlife Sanctuary. Hence, we believe, that by increasing the current study area, we can account for these gaps in conservation areas, more effectively.

• Journal of Ecology and Environment
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• 제33권4호
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• pp.271-274
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• 2010

The Ministry of Environment of South Korea has launched its plan to establish the National Ecological Institute. An International Symposium and Workshop was held at Ewha Womans University in Seoul on Thursday, 30 September 2010, to strengthen international cooperation, networking and partnerships for the conservation of biodiversity. This symposium was attended by experts of many major institutions for biodiversity conservation from South Korea and overseas. At the symposium and workshop preceded by a keynote speech by the renowned primatologist and conservation biologist Jane Goodall the participants discussed a wide range of topics including "biodiversity conservation: in situ and ex situ approaches", "conservation of species diversity and ecosystem management", and "international cooperation for biodiversity conservation and research". As a basis for future discussions, this article summarizes how the National Ecological Institute might contribute most effectively to public life and environmental management in South Korea and worldwide. It addresses the following issues: governance and funding, synergies within Korea, participation in international networks, external advice, a broad view of ecological issues, research agenda, building on identity, public outreach, and training the next generation of scientists.

• 한국산림과학회지
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• 제83권3호
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• pp.299-310
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• 1994

본 연구는 강원도 춘천군에 위치한 임업진흥촉진지역(林業振興促進地域)을 대상으로 총수확비용(總收穫費用)(임도개설비(林道開設費)+집재비(集材費))을 최소화하는 양방향(兩方向)-단계집재(段階集材) 및 이단계집재(二段階集材)를 위한 적정임도간격(適正林道間隔) 및 임도밀도(林道密度)를 산출하였다. 이때의 임도개설비(林道開設費)는 km당 천만원부터 6천만원까지이다. 그 결과는 다음과 같다. 양방향(兩方向)-단계집재(段階集材)에서는 케이블 크fp인이 적합하며, 적정임도간격(適正林道間隔)은 1,698m~4,192m,평균 3,087m이며, 임도밀도(林道密度)는 3.44m/ha~8.44m/ha, 평균 5.12m/ha로 산출되었다. 양방향(兩方向)-이단계집재(二段階集材)에서 중지형(中地形)은 중형집재기와 로깅부기의 조합기종이 적합하며 임도간격(林道間隔) 1,483m~3,481m, 평균 2,589m로서, 임도밀도(林道密度)는 4.05m/ha~9.46m/ha, 평균 5.90m/ha로 산출되었다. 또한 급지형(急地形)은 중형집재기와 진성윈치의 조합기종이 적합하며, 임도간격(林道間隔) 1,693m~3,982m, 평균 2,960m로서, 임도밀도(林道密度)는 3.68m/ha~8.64m/ha 평균 5.38m/ha로 산출되었다.

• 한국산림과학회지
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• 제98권2호
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• pp.197-202
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• 2009

We studied bird communities among in rice field (46 plots), short grallland (47plot), and tall grass mixed shrub (21 plots) during dry season, January 2007 in Boeung Prek Lapouv (BPL) Important Bird Area, Mekong Delta, Cambodia using the point-count method. Water depth, vegetation height and shrub density were significantly different among the three study areas. We recorded, 60 bird species, of which 13 differed significantly among habitats. Landbirds such as Grey-breasted Prinia (Prinia hodgsonii) and Oliver-black Sunbird (Nectarinia jugularis) were much more abundant (P<0.0001) in the tall grass mixed shrub, whereas the Sarus Crane (Grus antigone), herons and egrets were more abundant in the short grass (P<0.05). Bird species richness and species abundances were not significantly different among habitats. Bird species diversity (H') was higher in grasslands than in rice fields. Mosaic habitat matrix, such as rice field, short grass, and tall grass mixed shrub, should be maintained for the extend and quality of wetlands, and the prevailing human-land use patterns, appear adequate and conductive for waterbirds in the Mekong Delta, Cambodia.

• 한국산림과학회지
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• 제100권2호
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• pp.154-164
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• 2011

본 연구는 우리나라 험준한 급경사 지형의 단목중심의 목재생산시스템 등에 적합하고 사방사업, 임도사업 등의 다양한 산림작업에 유용하게 활용할 수 있는 다목적의 반궤도식 산림작업차 개발을 목적으로 실시하였다. 산림작업차량의 기본 차체는 최소회전반경 설계기준과 작업도 폭을 고려하여 차체프레임부의 총길이는 5,750 mm, 차체의 폭은 1,900 mm, 적재부의 적재용량은 약 $2.5m^{3}$으로 설계 제작하였다. 동력원은 3,400 rpm의 최대 96마력 출력의 엔진을 선정하였으며, 유압펌프는 2개의 주펌프와 2개의 보조펌프로 나누어 선정하고, 주펌프는 전후좌우 4개의 주행용 유압모터에 사용하고, 보조펌프는 각종 작업기에 사용하도록 설계 제작하였다. 동력전달방식은 HST(Hydro-Static Transmission) 시스템을 적용하였고, 주행부는 조향가능한 전방 고무바퀴와 무한 궤도형으로 회전하는 후방 크롤러로 설계 제작하고, 조향방식은 애커만 조향방식을 채택하였다. 주행조작부는 일반 자동차의 운전 및 운전석 형태로 설계 제작하였으며, 보조장치로 윈치와 로그그래플 및 아웃트리거를 장착하였다. 시작기의 공차시 임도의 주행속도는 저속 5.3 km/hr, 고속 7.7 km/hr로 나타났다.