• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.464-469
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• 2001

This work provides the biomechanical evaluations of a manual wheelchair with a bi-directional driving system. The new propulsion strategy can be accomplished by employing a special gear system that converts the oscillatory motion of a handrim into the unidirectional output motion of a wheel. A main feature of the forward. backward propulsion is to supply continuous driving torque without break. Motion. analysis has been performed through 2-dimensional image processing for measuring the kinematic properties of the upper arm and fore arm. Then, the inverse dynamics analysis has been done for obtaining the joint torques, the handrim forces and input/output powers. Results show that the output power by the forward. reverse propulsion is almost twice as much as that by conventional propulsion. Also, the new propulsion is expected to reduce the fatigues and injuries at arm joints by employing more muscle groups for movement. In conclusion, the forward. reverse propulsion can greatly improve the performances of manual wheelchairs by providing better mobility as well as by guaranteeing several advantages from a biomechanical viewpoint. Future development of a manual wheelchair optimized for the bi-directional propulsion will further improve the propulsion performances.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.299-303
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• 2004

In our pervious paper, a new parallel-type spherical 3-degree-of-freedom mechanism consisting of a two-degree-of-freedom parallel module and a serial RRR subchain was proposed[1]. In this paper, its improved version is suggested and implemented. Differently from the previous 3-dof spherical mechanism, gear chains are incorporated into the current version of the mechanism to drive the distal revolute joint of the serial subchain from the base of the mechanism and in fact, the modification significantly improves kinematic characteristics of the mechanism within its workspace. Firstly, after a brief description on its structure, the closed-form solutions of both the forward and the reverse position analysis are derived. Secondly, the first-order kinematic model of the mechanism for the inputs which are assumed to be located at the base is derived. Thirdly, through the simulations of the kinematic analysis via. kinematic isotropic index, it is confirmed that the mechanism has much more improved isotropic properties throughout the workspace of the mechanism than the previous mechanism in [1]. Lastly, the proposed mechanism is implemented to verify the results from this analysis.

• 로봇학회논문지
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• 제17권4호
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• pp.438-446
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• 2022

In this paper, we propose an intelligent three-legged landing system that can maintain stability and level even on rough terrain than conventional four-legged landing systems. Conventional landing gear has the limitation that it requires flat terrain for landing. The 3-leg landing system proposed in this paper extends the usable range of the legs and reduces the weight, allowing the quadcopter to operate in various environments. To do this, kinematics determine the joint angles and coordinates of the legs of the two-link structure. Based on the angle value of the quadcopter detected via the IMU sensor, the leg control method that corrects the posture is determined. A force sensor attached to the end of the leg is used to detect contact with the ground. At the moment of contact with the ground, landing control starts according to the value of the IMU sensor. The proposed system verifies its reliability in various environments through an indoor landing test stand. Finally, in an outdoor environment, the quadcopter lands on a 20 degree incline and 20 cm rough terrain after flight. This demonstrates the stability and effectiveness of the 3-leg landing system even on rough terrain compared to the 4-leg landing system.

• 대한기계학회논문집A
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• 제34권1호
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• pp.85-90
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• 2010

자동차 후진기어용 축재는 단조재로서 그 형상은 복잡하고 열처리 및 가공공정이 어려울 뿐 아니라, 제품수명 저하 등의 문제점으로 인한 경제적 손실이 크다. 따라서 종전의 일체형 단조품을 캠 형상 부분만을 기존의 단조품(SF 45)으로 사용하고, 나머지 축 부분은 일반 기계구조용 탄소강재(SM 45C)로 대체를 위한 이종마찰용접을 적용하였다. 마찰용접 변수인 회전수, 마찰압력, 업셋압력, 가열시간, 업셋시간 등의 상호작용에 의한 용접품질과의 상관관계를 고찰하였으며, 최적조건에서 마찰용접을 한 후 용접재(as-welded)와 고주파 열처리를 시행한 후열처리재(PWHT)의 접합부 특성을 비교 고찰하였다. 이는 종전의 일체형 단조품에 비해 단조비용 절감, 피로수명향상, 기계가공에 따른 공정수 및 재료절감 등의 경제적 파급효과가 클 것으로 기대된다.

• 수산해양교육연구
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• 제9권2호
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• pp.121-148
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• 1997

The Japanese fishery management system has been established on the basis of various experience accumulated over many years. The fishery management system in Japan, one of the oldest fishery management systems in the world, is aimed at ensuring comprehensive utilization of the water surface and developing fishery productivity, by giving protection of the breeding environment of aquatic animals and plants, enabling the appropriate use of fishery grounds, preventing and solving disputes over fishery grounds and making other fishery adjustments. Japanese Fishery Law has been changed largely into (1) The Feudal Era(to 1900), (2) The Oldest Fishey Law(1901~48), (3) Current Fishery Law(1949 to present). Japanese fishery legislation is designed as a single package combining coastal, offshore and distant-water fisheries. During the period of the old fishery law, numerous conflicts arose over the joint use of fishing grounds and fish stocks. Such conflicts occurred among users of the same gear as well as between users of different gears or of different sizes of fishing craft. Large scale conflict sometime occurred between neighbouring fishing communities due to a lack of fairness in principle and coordination in practice. Therefore, the new fishery law enacted in 1949. This law was designed primarily to realize the most effective and rational use of fishing grounds and fishery resources, the basic philosophy being that, through democratic organization by fishermen themselves, productivity would be stimulated and incomes and living standards eventually improved. Nowadays, Community Based Fisheries Management through democratic organization by fishermen themselves have to enforce at coastal fisheries. This Community Based Fisheries Management manage to fishery resources by fishermen themselves and harvest in collaboration with that resources. Therefore, this paper is intended to briefly to describe the entire system and the historical development of Japanese fishery legislation in order to assist in reform of our country fisheries management regime.

• 반도체디스플레이기술학회지
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• 제21권4호
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• pp.65-70
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• 2022

In manufacturing and semiconductor industries, transfer robots increase productivity through accurate and continuous work. Due to the nature of the semiconductor process, there are environments where humans cannot intervene to maintain internal temperature and humidity in a clean room. So, transport robots take responsibility over humans. In such an environment where the manpower of the process is cutting down, the lack of maintenance and management technology of the machine may adversely affect the production, and that's why it is necessary to develop a technology for the machine failure diagnosis system. Therefore, this paper tries to identify various causes of failure of transport robots that are widely used in semiconductor automation, and the Prognostics and Health Management (PHM) method is considered for determining and predicting the process of failures. The robot mainly fails in the driving unit due to long-term repetitive motion, and the core components of the driving unit are motors and gear reducer. A simulation drive unit was manufactured and tested around this component and then applied to 6-axis vertical multi-joint robots used in actual industrial sites. Vibration data was collected for each cause of failure of the robot, and then the collected data was processed through signal processing and frequency analysis. The processed data can determine the fault of the robot by utilizing machine learning algorithms such as SVM (Support Vector Machine) and KNN (K-Nearest Neighbor). As a result, the PHM environment was built based on machine learning algorithms using SVM and KNN, confirming that failure prediction was partially possible.

• 한국운동역학회지
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• 제26권1호
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• pp.11-20
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• 2016

Objective: This study aimed to compare biomechanical data between elite and beginner cyclists during cycle pedaling by performing a comparative analysis and to provide quantitative data for both pedaling performance enhancement and injury prevention. Methods: The subjects of this study included 5 elite cyclists (age: $18{\pm}0years$, body mass: $64.8{\pm}9.52kg$, height: $173.0{\pm}4.80cm$) and 5 amateur cyclists (age: $20{\pm}0years$, mass: $66.6{\pm}2.36kg$, height: $175.6{\pm}1.95cm$). The subjects pedaled on a stationary bicycle mounted on rollers of the same gear (front: 50 T and rear: 17 T = 2.94) and cadence of 90. The saddle height was adjusted to fit the body of each subject, and all the subjects wore shoes with cleats. In order to obtain kinematic data, 4 cameras (GR-HD1KR, JVC, Japan) were installed and set at 60 frames/sec. An electromyography (EMG) system (Telemyo 2400T, Noraxon, USA) was used to measure muscle activation. Eight sets of data from both the left and right lower extremities were obtained from 4 muscles (vastus medialis oblique [VMO], vastus lateralis oblique [VLO], and semitendinosus [Semitend], and lateral gastrocnemius [Gastro]) bilaterally by using a sampling frequency of 1,500 Hz. Five sets of events ($0^{\circ}$, $90^{\circ}$, $180^{\circ}$, $270^{\circ}$, and $360^{\circ}$) and 4 phases (P1, P2, P3, and P4) were set up for the data analysis. Imaging data were analyzed for kinematic factors by using the Kwon3D XP computer software (Visol, Korea). MyoResearch XP Master Edition (Noraxon) was used for filtering and processing EMG signals. Results: The angular velocity at $360^{\circ}$ from the feet was higher in the amateur cyclists, but accelerations at $90^{\circ}$ and $180^{\circ}$ were higher in the elite cyclists. The amateur cyclists had greater joint angles at $270^{\circ}$ from the ankle and wider knee joint distance at $0^{\circ}$, $180^{\circ}$, and $360^{\circ}$ than the elite cyclists. The EMG measurements showed significant differences between P2 and P4 from both the right VLO and Semitend. Conclusion: This study showed that lower body movements appeared to be different according to the level of cycle pedaling experience. This finding may be used to improve pedaling performance and prevent injuries among cyclists.

• 시큐리티연구
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• 제36호
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• pp.93-109
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• 2013

본 연구에서는 경호, 경비현장에서 이루어지는 대치상황에서 경호, 경비원의 장비 중 삼단봉을 선택하여 머리치기 동작의 운동학적 분석을 실시하였다. H대학교 경호학과 학생 출신10명을 대상으로 연구를 실시하였다. 숙련자 그룹에서 삼단봉 교육 프로그램 실시하였고, 숙련자그룹과 비숙련자 그룹으로 연구 하였다. 구간별 소요시간은 숙련자 (e2) 0.428sec 비숙련자 0.435 sec, (e3) 에서는 숙련지 0.230 sec 비숙련자 0.232 sec 소요되었으며, 비숙련자 그룹에서 소요시간이 많이 소요된 것으로 나타났다. 신체중심 이동 변위는 좌, 우 숙련자$2.16{\pm}0.95cm$, $3.78{\pm}1.42cm$, 전체적으로 $5.94{\pm}2.03cm$ 변화를 보였다. 비숙련자 $2.97{\pm}1.01cm$, $4.56{\pm}1.57cm$, 전체적으로 $7.53{\pm}2.13cm$ 변화를 보였고, 전, 후 이동에서는 숙련자$32.48{\pm}3.86cm$, $35.21{\pm}4.64cm$, 전체적으로 $69.36{\pm}5.72cm$ 변화를 보였다. 비숙련자 $34.50{\pm}6.12cm$, $37.04{\pm}3.70cm$, 전체적으로 $71.46{\pm}7.17cm$ 변화를 보였다. 그리고 상, 하 이동변위에서는 숙련자 $5.62{\pm}2.49cm$, $4.54{\pm}1.87cm$, 전체적으로 $10.11{\pm}1.57cm$ 변화를 보였다. 비숙련자 $6.33{\pm}1.78cm$, $4.86{\pm}1.85cm$, 전체적으로 $10.68{\pm}1.81cm$ 변화를 보였다. 손목관절의 각도 변화에서 손목각도이며, 숙련자e1, $114.62{\pm}7.13$, e2 $68.27{\pm}6.37$, e3 $131.64{\pm}6.27$, 비숙련자 e1, $112.62{\pm}6.13$, e2 $66.28{\pm}7.38$, e3 $137.42{\pm}4.28$ 팔꿉치 관절의 각도 변화이며, 숙련자 e1, $132.31{\pm}6.55$, e2 $117.92{\pm}8.42$, e3 $144.41{\pm}6.32$, 비숙련자 e1, $133.58{\pm}8.56$, e2 $114.45{\pm}8.21$, e3 $139.89{\pm}4.38$ 어깨관절의 각도 변화이며, 숙련자 e1, $13.55{\pm}3.85$, e2 $131.42{\pm}11.24$, e3 $78.32{\pm}6.28$, 비숙련자 e1, $9.45{\pm}1.23$, e2 $136.74{\pm}13.21$, e3 $79.75{\pm}4.24$, 각 변화를 보였다.