• Journal of the Ergonomics Society of Korea
• /
• v.30 no.3
• /
• pp.395-401
• /
• 2011

Objective: This study examined the effects of working chair that was developed for farmers who work in grapevine's cluster thinning. Background: Agricultural work involves some of the nation's highest occupational risk exposures. Fruit cultivation has been recognized as one of the most hazardous crops in which to work. Grapevine cluster thinning task involve activities related to the main risk factors associated with upper limb work-related musculoskeletal disorders. Method: An experiment was designed to test the working chair. Six healthy male($25.8{\pm}4.9years$) were selected as the subjects for this study. Electromyography(EMG) was used to monitor the muscles activity, and Electro-goniometer was used to measure the ranges of motions of the elbow, trunk and knee. Subjective test was also carried out to examine discomfort body parts and their pain intensity. A grapevine's working space was built for the experiment and working chair was installed on it. In order to examine the muscle activity and range of motion, subjects used to the working chair for 30 minutes for each experimental condition. Another test without working chair was also performed for comparison. %MVC was used to quantify the level of muscle activity. Results: Decreases of muscle activity was found in all leg muscles and significant decrease of muscle activity was found in left Gastrocnemius. The range of motion of the trunk and knee also decreased when working chair used. Discomfort in lower back, thigh and shank region were reduced significantly. However, in upper limbs muscle activity tended to increase in working chair compared with conventional task. Conclusion: Improvement for cushion in seat back and pan required to reduce discomfort in buttocks. Application: Overall findings verified that the working chair might help to prevent upper limb and lower back MSDs based on the current study. These results can be practically used for work improvement for the grapevine growers to prevent MSDs.

• Transactions of Materials Processing
• /
• v.11 no.2
• /
• pp.138-146
• /
• 2002

This paper is concerned with the simulation-based process design method involved non-steady state problem of tension levelling considering the elasto-plastic hardening behavior of a metallic strip by a commercial code ABAQUS/Standard. The tension levelling process is peformed to elongate the strip plastically in combination of tensile and bending strain by a controlled manner so that all longitudinal fibers in the strip have an approximately equal amount of length and undesirable strip shapes are corrected to the flat share. Objectives of this paper are the development of a general method for the design of a tension leveller by a finite element method and parameter studies for the deisgn variables such as the applied tension, the roll intermash includes the determination of the steady state using the simple unit of the tension levelling line and the effect of the finite element mesh size on the amount and distribution of the strain calculated. The analysis provides the information about the intermesh effect on the amount and final shapes of the strip and distribution of the strain in order to determine the amount elongation for correction of the irregular share.

• Journal of Korea Multimedia Society
• /
• v.17 no.6
• /
• pp.671-680
• /
• 2014

Recently, with the remarkable increase of social network services, it is necessary to extract interesting information from lots of data about various individual opinions and preferences on SNS(Social Network Service). The sentiment information can be applied to various fields of society such as politics, public opinions, economics, personal services and entertainments. To extract sentiment information, it is necessary to use processing techniques that store a large amount of SNS data, extract meaningful data from them, and search the sentiment information. This paper proposes an efficient method to extract sentiment information from various unstructured big data on social networks using HDFS(Hadoop Distributed File System) platform and MapReduce functions. In experiments, the proposed method collects and stacks data steadily as the number of data is increased. When the proposed functions are applied to sentiment analysis, the system keeps load balancing and the analysis results are very close to the results of manual work.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.983-984
• /
• 2007

The spindle motor used on the ODD has a characteristic that electromagnetic pulsation and noise change differently by magnetization pattern of rotor. Therefore, design of magnetizer yoke that make to have optimal magnetization pattern is very important. In this paper, we proposed an analysis method that applies magnetizer analysis result to the spindle motor. We measured back-EMF of the real spindle motor. And then, we verified validity of the proposed analysis method by comparing the measurement and analysis result. Also, we designed the magnetizer shape that has optimal magnetization pattern by using proposed method. As a result, we reduced cogging torque of the spindle motor.

• Journal of the Korean Society of Physical Medicine
• /
• v.4 no.3
• /
• pp.133-140
• /
• 2009

Purpose：To investigate the effect of the home exercise program on pain, scoliosis, pelvic alignment of low back in chronic back pain patients, and suggest optimal method for home exercise program. Methods：I divided into two groups who has chronic back pain; one is control group who was given a treatment at the hospital only and the other is experimental group who did another exercise after treatment at the hospital, and there were 10 people in each group. The manual therapy were given to all the patients in each group after applying a stupe and an electric treatment, but the experimental group conducted another exercise program at homes. All the exercise programs were applied to patients 12 times for 4 weeks totally. Results：SPSS for win version 12 was used for statistic analysis and independent t-test was used to find changes between two groups. VAS scale was used to show changes in pain between each group. The grade of pain was decreased between pre&post test to -5.60 in control group and -4.80 in experimental group but there wasn't significant difference between each group. Cobb's degree was used to compare the changes of scoliosis in lumbar and it was improved in each group but there wasn't significant difference between each group. The measurement of pelvic misalignment was decreased between pre&post test to -1.00 in control group and -2.00 in experimental group but it wasn't enough to show significant difference between each group. Conclusion：As you read the results above, for a chronic low back pain patient, application of the manual therapy showed that it has effect on decrease of low back pain, improvement of scoliosis in lumbar and pelvic misalignment. However, the effect of home exercise treatment was not sure about improvements for chronic low back pain patient. So I think there should need further study about the effect of home exercise treatment except the treatments at hospital and the thorough education for the exercise of lumbar should be done before the study for the accurate experiment.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.1476-1480
• /
• 2005

본 연구에서는 매개변수를 추정하는 방법 중 하나인 역해석을 이용하여 강변여과 지역의 투수량계수를 추정하였다. 최적화 기법으로 BFGS(Broyden-Fletcher-Goldfarb-Shanno)를, 정해석 프로그램으로 지하수위와 오염물 거동을 2차원적으로 모의할 수 있는 MOC(Method of Characteristics)을 이용하여 포트란으로 구성된 새로운 프로그램을 개발하였으며 프로그램의 적용성을 검증하기 위해 실제 강변여과를 하고 있는 경남 창원시 대산면의 8개월간 관측 지하수위를 이용하여 그 지역의 투수량계수를 추정하였다.

• Proceedings of the KIEE Conference
• /
• 1989.07a
• /
• pp.447-450
• /
• 1989

Single particle orbit in plasma is obtained by drift Hamiltonian formulation in magnetic coordinate. The collisional effect is implied by Monte Carlo Method and the velocity space diffusion, energy transfer to the back ground plasma and the variation of energy distribution of test particles are investigated from many particles analysis.

• 제어로봇시스템학회:학술대회논문집
• /
• 1986.10a
• /
• pp.601-606
• /
• 1986

In this paper, two methods of power circuit simulation is described in order to obtain the back data for design of current source inverter. One is steady-state analysis by differential equations during the various operating modes. Another method uses switching function, which represents the switching pattern of inverter, and direct-guadrature model of induction motor. The results of digital computer simulation by two methods are compared with the results of laboratory test.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.6
• /
• pp.616-622
• /
• 2000

This paper concerns the application of smoke and fire spread to road tunnel fire problems. When a road tunnel is on fire. a fire protection system of road tunnel have to offer an adequate escape space to human. Therefore, this study carried out a simulation for predicting a spreading path of smoke and fire. The evolution of the flow field is simulated with the low Reynolds number k-$\varepsilon$ turbulent model and SIMPLE algorithm based on the finite volume method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.1 s.232
• /
• pp.145-155
• /
• 2005

In this study, a finite element method program code which can be accomodate boundary conditions on the complex surfaces has been developed to simulate polymer extruder processes. The analysis method includes the fractional 4-step method for efficient computation time and compact usage of memory storage to solve the velocities and the pressure values from the Navier-Stokes equation. By using the developed program which was verified with simple Poiseuille flow mixture phenomena in single-and twin-screw extruder are analyzed. It is concluded that the proposed method resulte Poiseuille Poiseuille d in fair agreement with the exact solution of simple flow and the back flow near the entrance happens in single-screw model. It is identified that the location and values of maximum pressure in the twin screw extruder model. It is expected that the Velocity field found can be used to predict the degree of mixture in the extruder barrel.