• 항공우주시스템공학회지
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• 제11권6호
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• pp.26-33
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• 2017

본 연구에서는 외골격 크기를 변화하여 효과적으로 구동력을 조절하고 우수한 장애물 통과능력을 가진 구형로봇을 구현하였다. 호버만구를 외골격으로 채택하고 슬라이더-크랭크 구조의 확대 수축 메커니즘을 설계하여 무선으로 로봇의 크기변화와 이동제어가 가능하도록 제어시스템을 구축하였다. 로봇의 효율적인 구동에 필요한 주요 변수를 확인하기 위하여 오일러-라그랑주 운동방정식을 세워 해석하였고, 이를 바탕으로 DC 모터를 선정하였다. 로봇의 성능을 평가하기 위해 Prototype 의 기초 구동실험을 진행함과 동시에 유한요소 해석을 통해 구조적 안정성을 보완한 최종 모델을 제작하였다. 결과적으로, 외경 기준 최대 650 mm 에서 최소 520 mm 까지 수축/팽창이 가능한 로봇이 0.85 m/s로 주행이 가능한 것을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제41권1호
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• pp.62-69
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• 2017

본 논문은 외벽에 부착하여 이동이 가능한 등반로봇의 성능평가 방법을 다룬다. 등반로봇에 관한 기존의 문헌을 토대로 볼 때, 등반로봇의 성능평가에 관해 일관되고 명쾌한 성능지표 및 방법이 제시되고 있지는 않다. 등반로봇은 부착방식 및 이동방식에 따라 다양하게 구현될 수 있으므로, 형태와 상관없이 보다 일반화된 성능평가 방법이 요구된다. 이에 본 논문은 등반로봇의 성능평가를 위한 2가지 평가지표(수직부착하중, 수직등반속도)와 평가방법을 제안한다. 제안된 방법의 효용성을 검증하기 위하여, 본 논문은 자체 개발된 선체외벽 등반로봇을 대상으로 제안된 성능평가 방법을 적용한다. 보다 구체적으로, 수직부착하중은 등반로봇의 슬립측정을 통해 18.5kg으로 평가되었고, 수직등반속도는 등반로봇의 위치제어시스템을 통해 41cm/s으로 평가되었다.

• 제어로봇시스템학회논문지
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• 제8권4호
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• pp.345-350
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• 2002

In recent years, as changing the habit of eating, the pathology in the colon grows up annually. The colonoscopy is generalized, but if requires much time to acquire a dexterous skill to perform an operation and the procedure is painful to the patient. biomedical and robotic researchers are developing a locomotive colonoscope that can travel safe1y in colon. In this paper, we propose a new actuator and concept of semi-autonomous colonoscope. The micro robot comprises camera and LED for diagnosis, steer- ing system to pass through the loop, pneumatic actuator and bow-shaped flexible supporters to control a contact force and to pass over haustral folds in colon. For locomotion of semi-autonomous colonoscope, we suggest an actuator that is based on impact force between a cylinder and a piston. In order to validate the concept and the performance of the actuator, we carried out the simulation of moving characteristics and the preliminary experiments in rigid pipes and on the colon of pig.

• Asian-Australasian Journal of Animal Sciences
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• 제22권11호
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• pp.1574-1580
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• 2009

To evaluate the effect of different housing systems on sow behavior, 80 gilts were randomly allocated at puberty to four treatments: i) sow stall in gestation followed by farrowing crate (SC), ii) group housing with individual feeding in gestation followed by farrowing crate (GC), iii) ESF (Electronic Sow Feeding) system in gestation followed by farrowing crate (EC), and iv) ESF system followed by group farrowing pen (EG). Behavioral observations were carried out on a total of 16 animals per treatment at the following stages: first day of allocation to housing treatment, day of service, 80 days after service, 109 days after service on entry to farrowing accommodation, 24 h before farrowing, day of farrowing, 14, 27 and 28 days after farrowing, at weaning. On each occasion, individual animals were observed for a 24 period with one minute time sampling. There were significant differences (p<0.001) between stages of the reproductive cycle for all the behavior patterns in all treatments. On the first day in experimental housing treatments, sows spent more time rooting and dog-sitting. Activity and investigatory behavior decreased as pregnancy progressed. An activity peak was apparent just before farrowing, followed by a high level of inactivity on the day of farrowing. Time spent active, eating and drinking increased as lactation progressed, and greatest activity and locomotion was seen immediately following weaning. There were significant differences between housing treatments (p<0.01) for standing, moving, eating, drinking, dog-sitting and lying. During pregnancy SC sows spent more time standing, rooting, drinking and dog sitting, while EC sows spent less time rooting and drinking and more time lying. During lactation, GC sows spent more time standing, moving and eating, less time dog sitting and lateral lying. Nursing frequency was reduced in GC sows (p<0.001). The maternal and piglet behaviors were influenced strongly by environment during lactation. However, it was also shown that previous housing history can influence the maternal behavior in the pre-farrowing stage and during early lactation.

• Safety and Health at Work
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• 제3권3호
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• pp.224-234
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• 2012

Objectives: This study was conducted in order to obtain information concerning the health hazards that may result from a 13 week inhalation exposure of n-pentane in Sprague-Dawley rats. Methods: This study was conducted in accordance with the Organization for Economic Co-operation and Development (OECD) guidelines for the testing of chemicals No. 413 'Subchronic inhalation toxicity: 90-day study (as revised in 2009)'. The rats were divided into 4 groups (10 male and 10 female rats in each group), and were exposed to 0, 340, 1,530, and 6,885 ppm n-pentane in each exposure chamber for 6 hour/day, 5 days/week, for 13 weeks. All of the rats were sacrificed at the end of the treatment period. During the test period, clinical signs, mortality, body weights, food consumption, ophthalmoscopy, locomotion activity, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were assessed. Results: During the period of testing, there were no treatment related effects on the clinical findings, body weight, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, relative organ weight, and histopathological findings. Conclusion: The no-observable-adverse-effect level (NOAEL) of n-pentane is evaluated as being more than 6,885 ppm (20.3 mg/L) in both male and female rats. n-pentane was not a classified specific target organ toxicity in the globally harmonized classification system (GHS).

• 대한기계학회논문집A
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• 제38권8호
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• pp.837-848
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• 2014

본 논문에서는 보행이 불편한 노인들의 효과적인 자가 재활을 위한 보행 보조 로봇의 개발에 대해 연구하였다. 개발된 로봇의 주요 특징은 크게 유아보행기 및 전동휠체어 메커니즘을 융합한 안전성 및 운동성향상과 가변저항 및 스테레오 카메라를 이용한 정확한 보행 추종 제어 알고리즘으로 나눌 수 있다. 구체적으로, 유아보행기의 메커니즘을 적용하여 사용자가 보행 중 넘어지는 사고로부터 안전을 확보하는 동시에 다리근육의 부담을 줄여줄 수 있는 골반지지대를 설계하였으며, 전동휠체어와 같이 구동모터를 이용하여 사용자가 적은 힘으로도 로봇을 이동시킬 수 있도록 하였다. 다음으로, 골반지지대에 부착된 가변저항을 이용하여 사용자의 보행 의도 및 방향을 로봇이 자동적으로 판단하고 사용자를 추종할 수 있도록 하였으며, 스테레오 카메라를 이용한 사용자 하체모션분석 알고리즘으로부터 추종 반응속도와 정확성을 한층 높였다. 최종적으로, 단계적인 보행 보조 실험을 통해 개발된 로봇의 사용자 보행 추종 성능을 실험적으로 검증하였다.

• The Korean Journal of Pain
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• 제32권1호
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• pp.12-21
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• 2019

Spinal cord contusion injury is one of the most serious nervous system disorders, characterized by high morbidity and disability. To mimic spinal cord contusion in humans, various animal models of spinal contusion injury have been developed. These models have been developed in rats, mice, and monkeys. However, most of these models are developed using rats. Two types of animal models, i.e. bilateral contusion injury and unilateral contusion injury models, are developed using either a weight drop method or impactor method. In the weight drop method, a specific weight or a rod, having a specific weight and diameter, is dropped from a specific height on to the exposed spinal cord. Low intensity injury is produced by dropping a 5 g weight from a height of 8 cm, moderate injury by dropping 10 g weight from a height of 12.5-25 mm, and high intensity injury by dropping a 25 g weight from a height of 50 mm. In the impactor method, injury is produced through an impactor by delivering a specific force to the exposed spinal cord area. Mild injury is produced by delivering $100{\pm}5kdyn$ of force, moderate injury by delivering $200{\pm}10kdyn$ of force, and severe injury by delivering $300{\pm}10kdyn$ of force. The contusion injury produces a significant development of locomotor dysfunction, which is generally evident from the $0-14^{th}$ day of surgery and is at its peak after the $28-56^{th}$ day. The present review discusses different animal models of spinal contusion injury.

• 대한의용생체공학회:의공학회지
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• 제22권5호
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• pp.459-468
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• 2001

Average Coordinate Reference System (ACRS) 방법은 인체 보행 분석 시 발생하는 실험오타를 줄이기 위해서 개발되었다. 실험적으로 측정되어지는 운동학 데이터가 인체 모델링 분석을 수행하기 위해서 사용되어지며. 그 모델의 정확성은 그 측정된 데이터에 직접적인 연관 관계가 있다. 그러나, 인체가 보행하는 동안에 피부의 움직임과 골격구조의 변형이 발생하고 또한 운동 분석 실험장비 자체가 가지고 있는 여러 가지의 한계 때문에. 그 실험 데이터에 정확도는 의문시되어 진다 개발된 ACRS 방법은. 인체 운동분석을 수행하는 여러 종류의 시스템에 적용할 수 있는데. 본 연구에서는 ACRS 방법을 광학적으로 추적이 되는 표적을 인체의 각 세그멘트에 붙인 시스템에 적용하였다 ACRS 방법에서는. 각 세그멘트에 붙어있는 각각의 표적들이 독립적으로 그 세그멘트 안에서 국부좌표계의 원점으로 취급되어질 수 있다. 실험 과정에서 발생하는 본래부터의 오타 때문에. 각 원점에서 계산된 Euler angle은 서로 상이한 값을 갖는다 실험 초기에 측정한 보정 세그멘트 기준 프레임의 지식을 이용하면, 각 표적 위치에서 계산된 Euler angles들의 평균값을 계산할수 있고, 그 평균값은 피부의 확장과 회전의 영향을 최소화한 값이다. 운동분석에 일반적으로 적응되는 Euler angle 방법과 개발된 ACRS 방법을 비교하여 보면. ACRS 방법을 사용하였을 때 오차가 줄어들었다 만약에, 보행 실험 데이터에 오타가 존재하지 않는다면, 절대좌표계를 사용한 무릎 관절의 분리와 관통된 거리는 일회 보행구간 동안에 제로가 될 것으로 생각된다. 일반적으로 적용되는 Euler angle 방법을 적용하였을 때, 분리와 관통된 거리는 약 18 mm 가지 분포가 되었고, 개발된 ACRS 방법을 사용하였을 시에는 약 12 mm 까지 분포가 되었다.

• Molecular & Cellular Toxicology
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• 제3권4호
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• pp.262-266
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• 2007

ENPP2, a 125 kDa secreted lysophopholipase D which originally identified as a tumor-motogen, Autotaxin, enhances cellular locomotion, cell proliferation, angiogenesis and cell survival by generating the signal molecule lysophosphatic acid or sphingosine-1-phosphate. Previous studies have suggested that expression of Autotaxin is associated with invasive phenotype in advanced breast carcinomas. Thus, to determine whether genetic alterations of ENPP2 gene are involved in the development or progression of breast cancer, we analyzed its somatic mutation in 85 breast carcinomas by single-stranded conformational polymorphism and sequencing. Overall, six ENPP2 mutations were found (7.0%), comprising five missense and one nonsense mutation (s). To our knowledge, this is the first report on ENPP2 mutation in breast carcinoma, and the data indicate that ENPP2 is occasionally mutated in breast carcinomas, and suggest that ENPP2 mutation may contribute to the tumor development in some breast carcinomas.

• Biomolecules & Therapeutics
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• 제12권4호
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• pp.242-249
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• 2004

The main aim of this study was to investigate stress related activities of Sun-ginseng extract as a candidate for anti-stress-related functional supplement by comparing its effect to those of red ginseng, which is also known to alleviate stress. Normal group was not exposed to stress while the control group was exposed to stress. Rats were orally administered once a day with 200 mg red ginseng (RG) extract, 100 or 200 mg Sun-ginseng (SG) extract/kg body weight. Mice were given water containing 400 mg red ginseng extract, 200 or 400 mg SG/100 mL potable water. Rats were given supplements for 5 days without stress, and 5 days with restraint and electroshock stress. After final stress, stress-related behavioral changes of experimental animals were recorded and levels of blood corticosterone were measured. Mice were given supplements for 5 days through drinking water, and then fatigue related motor activity were recorded. SG-supplementation partially blocked stress effect on locomotion and elevated plus maze test in rats, and also partially blocked stress-induced behavioral changes such as freezing, burrowing, smelling, facewashing, grooming and rearing behavior in rats. SG-supplementation decreased blood corticosterone level which is increased by stress in rats. Effects of SG may not be modulated by GABAnergic nervous system. SG-supplementation prolonged swimming time and staying time on the wire and rotarod wheel in mice. These results suggest that SG partially protects living organisms from stress attack in some cases and thus has the potential to be used as a functional food to alleviate stress response.