• Journal of Communications and Networks
• /
• 제6권1호
• /
• pp.38-45
• /
• 2004

The ABR point-to-multipoint connection is now playing a more important role than before. Many consolidation algorithms have been proposed to solve the consolidation noise problem and the slow transient response problem. But few timeout algorithms are proposed to handle the non-responsive branches for the multicast connections. Chen’s algorithm needs exchanging control messages between switches [9]. Besides, it may mistake a responsive branch as a non-responsive branch because of fast changes in source rates, which causes wrong information in BRM cells and may lead to network congestion and data losses in the responsive branch. We propose a simple timeout algorithm which can handle the non-responsive branches without exchanging message between switches. The timeout value for each switch is computed locally. Simulation results show that the proposed timeout algorithm can efficiently handle the non-responsive branches and utilize the available bandwidth within a small period of time. In addition, our algorithm could handle the situation when the source rates change quickly.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.689-694
• /
• 2004

To increase accurateness and reliability of the evaluation of power tool vibration transmitted to an operator, it is necessary to measure grip and feed forces during the measurement of hand-transmitted vibration. In the study a system was invented to measure the vibration and the grip and/or feed force, which consists of a measurement handle and a PC with data acquisition system and the software. Strain gauges and an accelerometer were mounted on the handle for the simultaneous measurement of the forces and the vibration. The program in the system makes it possible to monitor the grip and feed force during the tool operation so that the operator keeps the applying forces within the pre-determined range. Investigating the vibration total values, frequency-weighted root mean square accelerations at the handle, obtained at various conditions with control of the grip and feed force showed more consistency than those measured without force control. By using the system the experimenter can reduce uncertainty of the measured vibration.

• 대한인간공학회지
• /
• 제28권2호
• /
• pp.27-34
• /
• 2009

The purpose of this study was to evaluate aging (young and old), gender (male and female), and handle shape effects on grip force, finger force, and subjective comfort. Four handle shapes of A, D, I, and V were implemented by a multi-finger force measurement (MFFM) system which was developed to measure every finger force with different grip spans. Forty young (20 males and 20 females) and forty old (20 males and 20 females) subjects participated in twelve gripping tasks and rated their comfort for all handles using a 5-point scale. Grip forces were calculating by summation of all four forces of the index, middle, ring and little fingers. Results showed that young males (283.2N) had larger gripping force than old males (235.6N), while young females (151.4N) had lower force than old females (153.6N). Young subjects exerted the largest gripping force with D-shape due to large contribution of the index and middle fingers and the smallest with A-shape; however, old subjects exerted the largest with I-shape and the smallest with V-shape due to small contribution of the ring and little fingers. As expected, the middle finger had the largest finger force and the little finger had the smallest. The fraction of contribution of index and ring fingers to grip force differed among age groups. Interestingly, young subjects provided larger index finger force than ring finger force, whereas old subjects showed that larger ring finger forces than index finger force in the griping tasks. In the relationship between performance and subjective comfort, I-shape exerting the largest grip force had less comfort than D-shape producing the second largest grip force. The findings of this study can provide guidelines on designing hand tool handle to obtain better performance as well as users' comfort.

• 대한인간공학회지
• /
• 제26권3호
• /
• pp.59-65
• /
• 2007

In this study, six grip spans (45mm-65mm) were tested to evaluate the effects of handle grip span and user's hand size on maximum grip strength, individual finger force, and subjective ratings of comfort using a digital dynamometer with individual force sensors. Forty-six males were assigned into three hand size groups according to their hand lengths. Results showed that overall 55mm and 50mm grip spans were the most comfortable sizes and associated with the highest grip strength in the maximum grip force exertions, whereas 65mm grip span was rated as the least comfortable size as well as the lowest grip strength. In the interaction effect of grip span and hand size, small and middle hand sized participants rated the best preference and the least preference grip spans differently with large hand sized participants. With respect to the analysis of individual finger force, the middle finger force was the strongest and the highest contribution to the total finger force, followed by ring, index and little fingers. In addition, it was noted that each finger had a different optimal grip span for exerting maximum force resulting in a bowed contoured shaped handle for two-handle hand tools. Thus, the grip spans for two-handle hand tools might be designed according to the users' hand and finger anthropometrics to maximize performance and subjective perception of comfort.

• 한국안전학회지
• /
• 제26권1호
• /
• pp.58-64
• /
• 2011

This study evaluated the effects of the handle width(shoulder width, 1.25${\times}$shoulder width, 1.5${\times}$shoulder width), height(3 levels : knee, medium, knuckle) and horizontal angle($0^{\circ}$, $10^{\circ}$) on the pushing, lifting, and twisting strengths which were required for carrying single or two wheel barrows. Twelve healthy college students(male) participated in the experiment. In each experimental condition($3{\times}3{\times}2$=18), the subjects exerted three forces(pushing, lifting, and twisting clockwise). The experimental conditions and three forces were tested in random order, and a minimum 2 minutes of rest was provided between exertions. Results showed that the mean and maximum pushing forces showed greater values when the horizontal angle was $0^{\circ}$ than $10^{\circ}$(p=0.016). However, the three independent variables had no statistically significant effects on the lifting forces(p>0.1). The mean and maximum twisting forces increased as the handle width became larger(p<0.05). Also, there was a marginal effect of the horizontal angle(p=0.065) on the twisting force. From the results of this study, the horizontal angle of $0^{\circ}$ and the wider handle width were suggested for the design of single-wheel barrows.

• Safety and Health at Work
• /
• 제13권4호
• /
• pp.440-447
• /
• 2022

Background: Agricultural handle equipment is present on all production areas' farms. They are handy and portable; however, excessive use can lead to acute traumas or accidental injuries. Repetitive movements, awkward postures, and hand-arm vibrations predispose them to pain and work-related musculoskeletal disorders. The purpose of this study was to observe the interaction of handle equipment in terms of electromyographic activity and analyze the postural work-related alterations. Materials and methods: Twenty male agricultural operators, mean age 24±1.54 years, underwent the electromyographic analysis testing their muscular activities with a brushcutter, electric saw, and hedge trimmer in four different test conditions. Results: The brushcutter proved to be the agricultural handle equipment with the higher mean frequency (3.37±0.38 Hz) and root mean square (5.25±1.24 ms^-2). Furthermore, the digital postural analysis showed a general asymmetry of the main arm and the respective side of the trunk. The head resulted right inclined in the anterior frontal plane by 5.7°±1.2°; the right scapula lower than the left in the posterior frontal plane (8.5°±1.8°), and a working trunk inclination of 34.15°±5.7°. Conclusions: Vibrations of handle equipment and awkward working postures represent a risk for agricultural operators. Preventive measures are required to avoid young operators from experiencing musculoskeletal disorders all lifelong.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.295-298
• /
• 2004

Automobile door-handle is assembled with three parts that are base, skin and cover. Over-molding processing makes assembly of the base and skin. The skin part that was made by PVC polymer has various thickness. Plastic injection molding simulation of part including significant changed thickness as skin is an inaccuracy comparing with real injection molding. To solve this problem, two commercial flow prediction software that are Moldflow MPI and MAPS 3D were used in this study. Simulations were conducted for three types mesh. Taguchi method was applied for simulation experiments. It will be need to compare with simulation results and real over-molding behavior in the near future.

• 한국의류산업학회지
• /
• 제11권4호
• /
• pp.641-647
• /
• 2009

The purpose of this study was to evaluate the physical properties and handle of knitwears made with silver yarns. The four different knitted fabrics were made and compared: cotton(C), cotton/silver(CS), polyester(P), and polyester/silver(PS). If fabrics knitted with silver combined yarns, their electrical shield properties, UV-cut properties, anti-static properties, and air permeability were improved. As an additional effect this also improves the antibacterial properties of fabrics. It was found that overall physical properties and functional properties were improved by using silver yarn with cotton. The silver knitted fabric was found to be improved its softness and fullness hand for apparel.

• 한국경영과학회지
• /
• 제11권1호
• /
• pp.36-43
• /
• 1986

In this study, the fuzzy programming is extended to handle various types of membership functions by transformation of the complicated fuzzy programming problems into the equivalent crisp linear programming problems with single objective. It is well-known that the fuzzy programming problem with linear membership functions (i.e., ramp type) can be easily transformed into a linear programming problem by introducing one dummy variable to minimize the worst unwanted deviation. However, until recently not many researches have been done to handle various general types of complicated linear membership functions which might be more realistic than ramp-or triangular-type functions. In order to handle these complicated membership functions, the goal dividing concept, which is based on the fuzzy set operation (i. e., intersection and union operations), has been prepared. The linear model obtained using the goal dividing concept is more efficient and single than the previous models [4, 8]. In addition, this result can be easily applied to any nonlinear membership functions by piecewise approximation since the membership function is continuous and monotone increasing or decreasing.

• 한국정보통신학회논문지
• /
• 제16권2호
• /
• pp.266-272
• /
• 2012

본 논문에서는 차량 정보를 이용한 멀티뷰 주차 보조 시스템을 제안한다. 제안한 시스템은 운전자에게 차량 주변의 세 방향의 영상을 제공한다. 평행주차나 주차장에서 주차를 할 때 사각지역을 줄이고, 편안하고 안전한 주행을 위해 핸들 조정에 따라 와이드 앵글의 CCD 카메라 영상을 출력한다. 핸들 조향각과 기어 위치는 차량의 ABS ECU에서 OBD-II 포트를 통해 획득한다. 제안한 시스템은 차량 실험을 통해 성능을 확인하였다.