초음파 센서를 이용한 이동 로봇

배지훈,김종철,박경용,강민구,김갑일 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

In this paper, design and construction of mobile robot is conducted and the error reduction and obstacle avoidance techniques is introduced. Up to now, in the design of most mobile robots, there are emphasis on the compensation of tracking errors using the additional sensors and guidance method, rather than the reduction of the tracking errors of motor itself and wheel errors. In this purpose, high performance motor and encoder are used for the driving actuator, and the acceleration/deceleration technic is introduced to reduce the driving errors. Also ultrasonic sensor performs obstacle avoidance, which is proved using the driving test.

소아에서의 선천성 상완동맥 동맥류 : Case report and review of the literatures

배진선,설지영,김경헌,이영 大韓脈管外科學會 1995 大韓脈管外科學會誌 Vol.11 No.2

저 전력 이족 로봇의 계단보행에 관한 연구

배지훈,강민구,박경용,김갑일 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

In this paper, stair walking of small power biped robot is implemented by load sharing method of walking gait and adding body. Generally, in one foot standing, load is burdened to especial joint. Further, robot's foot is long steps and is lifted up high to go up stairs. So, especial joint is sometimes overloaded during walking and this makes walking impossible. This problem is solved in this paper using adding body, load sharing method and kick action. By this ways, stair walking of small power biped robot can be implemented without overload to joint.

퍼지제어를 이용한 이족보행 로봇의 보행

배지훈,강민구,김종철,김갑일 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

In this paper, a biped robot is designed and implemented, and walking tests are performed using a stable walking model. In order to embody the human joint structure, designed biped robot has two degree of freedom attached to the pelvic area of each leg. Using two motors for each ankle makes it possible to have the same degree of freedom as human ankle. This paper show that fuzzy control algorithm is suitable for each joint control.

자일리톨 섭취에 따른 Streptococcus mutans의 글루칸 생성관련 유전자 발현 억제효과

김지혜,이영은,안상헌,최연희,남순현,송근배 大韓小兒齒科學會 2009 大韓小兒齒科學會誌 Vol.36 No.4

본 연구에서는 장기적인 자일리톨의 섭취가 Streptococcus mutans의 대표적인 독성인자 중 하나인 글루칸 생성에 미치는 영향을 알아보기 위하여 글루칸 합성효소인 glucosyltansferase의 mRNA 발현을 실시간 역전사 중합효소 연쇄반응을 통해 평가하여 다음과 같은 결과를 얻었다. 1. 24개월 동안 자일리톨껌을 섭취한 군에서 타액 내 Streptococcus mutans의 colony 수는 통계적으로 유의하게 감소하였다(p<0.05). 2. 비수용성 글루칸 합성에 관여하는 유전자인 gtfB, gtfC의 발현은 자일리톨껌을 섭취한 군에서 시간이 지남에 따라 유의 하게 감소하였다(p<0.05). 특히 gtfB의 발현은 12개월과 24개월째 대조군에 비하여 통계적으로 유의하게 낮았고, gtfC의 발현은 24개월째 대조군에 비하여 통계적으로 유의하게 낮았다(p<0.05). 3. 수용성 글루칸 합성에 관여하는 유전자인 gtfD의 발현 역시 자일리톨껌을 섭취한 군에서 시간이 지남에 따라 유의하게 감소하였다(p<0.05). 또한 gtfD의 발현은 12개월과 24개월째 대조군에 비하여 통계적으로 유의하게 낮았다(p<0.05). 이상의 결과들을 종합해 보았을 때, 자일리톨의 섭취는 구강 내 Streptococcus mutans의 글루칸 합성 관련 유전자들의 발현을 억제시킴으로써 Streptococcus mutans의 수적인 감소를 가져오는 것으로 생각된다. Xylitol has the ability to reduce the adherence of Streptococcus mutans(S. mutans), which can make it easier to remove plaque, decrease acid production and inhibit dental caries. There are few reports on the effects of xylitol on the expression of the virulence related genes in S. mutans. This study examined the inhibitory effect of chewing gum containing xylitol on glucan synthesis related gene expression of S. mutans. Participants were voluntarily recruited for a women's oral health prevention program, classified into two groups(a control and a xylitol group), and then followed for 2 years. Twenty salivary samples were randomly selected from each group. Colony count and real-time reverse transcription polymerase chain reaction were used to analyze the characteristics of S. mutans. The following results were obtained: The S. mutans counts decreased steadily in the xylitol group over the study period(p<0.05). The expression of the virulence related genes (gtfB, gtfC and gtfD) was significantly lower in the xylitol group than in the control groups (p<0.05). In conclusion, these results suggest that chewing xylitol gum for a long period of time may reduce the expression of the genes associated with S. mutans virulence, which can result in a decrease growth of S. mutans colonies as a result.

빠른 보행을 위한 이족 로봇의 설계

강민구,배지훈,박경용,김갑일 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

In this paper, a biped robot is designed and implemented, and walking tests are performed using a fast walking model. In order to embody the human joint structure, designed biped robot has each two degree of freedom attached to the pelvic, knee, and ankle . Using two motors for each knee makes it possible to have the same walking as human walking and fast walking. Also in joint controller, PID control algorithm may causes variation to the robot, which make the system unstable. Therefore, a PD controller is used to limit the vibrations as much as possible allowing steady state error to a certain extent.

Simulation for Sensorless Dual Arm Coordination with Relative Internal Forces

Ji-Hun Bae(배지훈),Jae-Han Park(박재한),Ga-Ram Jang(장가람),Moon-Hong Baeg(백문홍) 제어로봇시스템학회 2012 제어로봇시스템학회 합동학술대회 논문집 Vol.2012 No.7

In this paper, we propose a simple and feasible control scheme for dual arm coordination without force/torque sensor information, especially, in the task of holding and lifting a box. That is a kind of hybrid force/position control based on virtual work theorem and virtual spring-damper hypothesis. We calculate the minimum force and direction to hold and lift a box considering the friction cone on the box surface, and control directly the desired force as a feedforward term in the open loop control manner. The result of computer simulation shows that sensorless dual arm manipulation can be realized with only relative kinematic information between each robot arm.

Formability of complex composite structures with ribs made of long carbon-fiber-reinforced prepregs

Bae, Ji-Hun,Han, Min-Gu,Chang, Seung-Hwan ELSEVIER (APPLIED SCIENCE) 2017 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.168 No.-

<P><B>Abstract</B></P> <P>A long fiber prepreg sheet (LFPS) composed of long carbon fibers with lengths of 50mm and a fast-curing epoxy resin was used to fabricate complex-shaped structures with ribs using thermal compression molding. The formability of the composite structures was evaluated for various compression pressures (10, 30, and 60MPa) and times (5 and 10min) at a fixed curing temperature (155°C). Using a single layer of LFPS, the highest geometric accuracy of the composite structure with ribs was 99.64%, and the highest average fiber volume fraction of the rib part was 29.82% under 30MPa for 10min. Furthermore, the highest flexural strength and modulus of the ribs were 253MPa and 18GPa, respectively, under the condition of 30MPa and 10min. These values increased to 366MPa and 26GPa, respectively, when two layers (a fiber volume fraction of 38.15%) were applied. Among the various thermoforming conditions, an applied pressure of 30MPa and a pressing time of 10min at 155°C were the most appropriate to achieve relatively excellent net-shape molding with improved mechanical properties.</P>

Characterization of low-velocity impact-induced damages in carbon/epoxy composite laminates using a poly(vinylidene fluoride–trifluoroethylene) film sensor

Bae, Ji-Hun,Lee, Sung-Woo,Chang, Seung-Hwan Elsevier Science Ltd 2018 Composites Part B, Engineering Vol.135 No.-

<P><B>Abstract</B></P> <P>In this work, low-velocity impact-induced damages such as matrix cracking and delamination in composite laminates made of unidirectional carbon fiber/epoxy and woven carbon prepregs with different stacking sequences were investigated by using a poly(vinylidene fluoride–trifluoroethylene) (P(VDF-TrFE)) film sensor. The effect of insertion of film sensor having various areal ratios on the structural integrity of the host composite was investigated by conducting tensile and short beam shear tests. The findings revealed that the degradation rates of the Young's modulus, strength, and inter-laminar shear strength were in the acceptable range; the degradation rate was 7–8% even under unrealistically harsh conditions. Subsequently, low-velocity impact tests were performed by using a drop-weight impact machine (11.77–28.25 J). For damage characterization of the composite laminates, four P(VDF-TrFE) film sensors were inserted at different sites in each composite laminate at the impact point. By considering the relationships between impact energy, voltage output from the sensors, and the corresponding material failure modes, an estimation technique for the potential failure of the composite laminates that experienced low-velocity impacts was suggested.</P>

Shear-deformed fabric sensor made of P(VDF-TrFE) for damage detection of draped composite structures: A feasibility study

Bae, Ji-Hun,Han, Min-Gu,Chang, Seung-Hwan Elsevier 2018 Composites Applied science and manufacturing Vol.113 No.-

<P><B>Abstract</B></P> <P>For the damage detection of complex-shaped composite structures fabricated by vacuum bag degassing molding with a draping process, a fabric sensor made of poly(vinylidene fluoride-trifluoroethylene), was constructed. Characterization of the fabric sensor by picture frame tests and an electromechanical test was carried out. The locking angle of the fabric sensor was around 30°, and the static sensitivity of the sensor increased with the shear angles owing to an overlapping effect. Subsequently, low-velocity impact tests were performed by using a drop-weight impact machine (2.35–7.06 J) to confirm the feasibility of the P(VDF-TrFE) fabric sensor for the damage characterization of the composite dome structures. As the first step of health monitoring method with a new type of sensor an estimation technique for the potential failure of the composite structures was suggested by considering the relationships between the impact energy and voltage signals from the fabric sensors.</P>