• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.195-198
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• 2006

Zinc phosphate coating is required in nearly all steel cold forging operations. However, the chemical byproducts of this lubricant system are difficult to dispose of and have a negative environmental impact. In order to replace zinc phosphate based lubricants partially or completely, candidate lubricant has been developed in this study. The performance evaluation of these lubricants was conducted using the double cup extrusion test and spike forging test. With the use of the commercial FEM code DEFORM, friction factor calibration curves, i.e. cup height ratio vs. punch stroke and spike height vs. punch stroke, were established for different friction factor values. By matching the cup height ratio and the punch stroke and spike height vs. punch stroke from experiment to that obtained from FE simulations, the friction factor of the lubricants was determined. Three water-soluble lubricants; namely, Mec Homat, Royalcoat, and the developed lubricant were found to perform comparable to or better than zinc phosphate.

• Physical Therapy Korea
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• v.22 no.2
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• pp.30-40
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• 2015

Robot-assisted rehabilitation therapy has been used to increase physical function in post-stroke patients. The aim of this meta-analysis was to identify whether robot-assisted gait training can improve patients' functional abilities. A comprehensive search was performed of PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Physiotherapy Evidence Database (PEDro), Academic Search Premier (ASP), ScienceDirect, Korean Studies Information Service System (KISS), Research Information Sharing Service (RISS), Korea National Library, and the Korean Medical Database up to April, 2014. Fifteen eligible studies researched the effects of robot-assisted gait training to a control group. All outcome measures were classified by International Classification of Functioning, Disability, and Health (ICF) domains (body function and structures, activity, and participation) and were pooled for calculating the effect size. The overall effect size of the robot-assisted gait training was .356 [95% confidence interval (CI): .186~.526]. When the effect was compared by the type of electromechanical robot, Gait Trainer (GT) (.471, 95% CI: .320~.621) showed more effective than Lokomat (.169, 95% CI: .063~.275). In addition, acute stroke patients showed more improvement than others. Although robot-assisted gait training may improve function, but there is no scientific evidence about the appropriate treatment time for one session or the appropriate duration of treatment. Additional researchers are needed to include more well-designed trials in order to resolve these uncertainties.

• Therapeutic Science for Rehabilitation
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• v.4 no.2
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• pp.63-71
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• 2015

Objective : The purpose of this study was to investigate the effects of vibratory stimulation applied to the left forearm on unilateral neglect in patients with stroke. Methods : The subjects were 11 unilateral neglect patients with stroke. They were divided into 2 groups; 6 experimental subjects and 5 control subjects. Both groups received standardized rehabilitation program and occupational therapy for the intervention of unilateral neglect in a day. In random order, line bisection test (LBT), Albert test, and star cancellation test (SCT) were conducted at baseline, the next day. During the process of all assessments of the next day, vibration stimulation was provided for the 6 subjects in the experimental group (EG), while the 5 subjects in CG carried out all assessments without vibration stimulation. Result : No significant differences were found between groups on any demographic variable or baseline assessments scores. In the next day, there was significant improvement in the EG for the LBT(p<0.05), Albert's test(p<0.05), and SCT(p<0.05). However, there was no significant improvement in the CG for the LBT(p<0.05), Albert's test(p<0.05), and SCT(p<0.05). Conclusion : These result indicate that vibratory stimulation has a positive effect on the unilateral neglect, and may be considered as alternative choice in clinical occupational therapy for reducing unilateral neglect.

• Physical Therapy Korea
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• v.17 no.2
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• pp.51-59
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• 2010

The Functional Independence Measure (FIM) is widely used to determine the dependency of activity of daily living in rehabilitation patients. The purposes of this study were to evaluate the unidimentionality of the FIM physical items and to analyze the validity of cross-functional levels in stroke survivors in Korea. Thirteen physical items of FIM were rated according to an ordinal scale of a 7-level classification. Two hundred and seventy-nine patients participated in the study (age range 18~92 years and 57% male). Six items-eating, bladder control, bowel control, transfer to and from the bed/wheelchair, transfer to and from the toilet, and bathing-showed misfits with the Rasch model. The most difficult item was 'bathing', the easiest item was 'bowel control'. Although there were several differences within functional levels, the hierarchical order of item measures was rather similar. 'Bathing' was the most difficult in high level patients (above 60), however 'stairs' was most difficult in the middle level (41~60) group. In the low level group (below 40), 'toileting' was the most difficult. In conclusion, the present study has shown several differences of item difficulty among functional levels. This result will be useful in planning interventions, and developing rehabilitation programs for stroke survivors.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.2
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• pp.159-169
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• 1985

The calculation of torsional vibration for marine diesel engine propulsion shafting is normally carried out by equalizing exciting energy to damping energy, or using the dynamic magnifier. But, with these methods, the vibration amplitudes are calculated only for resonance points and vibration amplitudes of other running speeds of engine are determined by the estimation. Recently, many energy-saving ships have been built and on these ships, two-stroke, supercharged, super-long stroke diesel engines which have a small number of cylinders are usually installed. In these cases, the first order critical-torsional vibrations of these engine shaftings appear ordinarily near the MCR speed and the stress amplitudes of their vibration skirts exceed the limit stress defined by the rules of classification society. To predict the above condition in the design stage, the synthesized vibration amplitudes of all orders which are summed up according to their phase angles must be calculated from the drawings of propulsion shaft systems. In this study, a theoretical method to fulfill the above calculation is derived and a computer program is developed according to the derived method. And a shafting system of two-stroke, super-long stroke diesel engine which was installed in a bulk carrier is analyzed with this method. The measured values of this engine shafting are compared with those of calculated results and they show a fairly good agreement.

• 연구논문집
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• s.28
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• pp.49-58
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• 1998

In order to analyse the scavenging efficiency in a poppet valve type 2-stroke engine. visualization of scavenging flow and quantitative experiments for measuring scavenging efficiency were performed. The effect of shroud angle in RSSV which was developed by KIMM was evaluated under steady flow rig applying single-cycle method. Also dynamic simulator was used by using gas sampling with $CO_2$ and $O_2$gas. The $90^circ$ shroud RSSV was found to be the highest efficient system, and single-cycle and dynamic simulator test are very effective to save time and cost for the development of a 2-stroke engine.

• PNF and Movement
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• v.8 no.2
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• pp.37-46
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• 2010

Purpose : The purpose of this study was to investigate the performance level of functional independence of the stroke patient. Methods : In order to find out the functional independence of stroke patient, 160 peoples, 80 peoples in a large city and 80 peoples in small-to-medium sized city, were questioned. Result : The results of this study were as follows: 1. Functional independence level due to social factor; The comparison of functional independence level between two groups showed significant difference in educational level, religion, family member, vocation, and medical fees(P<.05). However, the two groups did not show significant difference in spouse. 2. Functional independence level due to environment factor; The comparison of functional independence level between two groups showed significant difference in place of residence and residental environment(P<.05). However, each group did not show significant difference. Conclusion : These results suggest that realization of stable housing, educational level, various physical activities, and diversified family members is essential. Also, stable environment and social satisfaction are needed to maintain and improve the health of patient.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.106-113
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• 2011

The conventional grounding impedance of a counterpoise is calculated as a function of the length of the counterpoise by use of the distributed parameter circuit model with an application of the EMTP(Electromagnetic Transient Program). The adequacy of the distributed parameter circuit model is examined and verified by comparison of the simulated and the measured results. The conventional grounding impedance of the counterpoise is analyzed for the first short stroke and subsequent short stroke currents. As a result, the simulated results show that the minimum conventional grounding impedance gives at a specified length of the counterpoise. The shorter the time taken to reach the peak of injected currents, the shorter the length of the counterpoise having the minimum conventional grounding impedance. We also present the critical lengths of the counterpoise for short stroke currents as a function of soil resistivity. Based on these results, it is necessary to compute the length of the counterpoise in a specified soil resistivity which satisfies both the low conventional grounding impedance requirement whilst also providing a suitable ground resistance in order to obtain an economical design and installation of the counterpoise.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.50-58
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• 2021

Objective: This study aimed to determine the effect of wrist and trunk weight loading using sandbags in stroke patients in order to provide the quantitative data for enhancement of gait movement. Method: Twelve stroke patients, who have been diagnosed with hemiplegia over a year ago, were participated in this study. All subjects were asked to perform normal walking [N], wrist sandbag walking [W], wrist & trunk sandbag walking [WT], and both wrist sandbag walking [B] and both wrist & trunk sandbag walking [BT], respectively. Eight infrared cameras were used to collect the raw data. Gait parameters, arm swing, shoulder-pelvic kinematics, and lower extremity joint angle were calculated to examine the differences during walking. Results: As a result, there were no significant differences in the gait parameters, shoulder-pelvis, and lower extremities joint angles, but significant differences were found in the range of motion and the anteversion in arm swing. Conclusion: Wrist and trunk weight loading using sandbags affected the movement of the upper extremities only while it did not affect the movement of the lower extremities. It implies that it can reduce the risk of falling caused by a sudden movement change in lower extremities. In addition, the wrist and trunk weight loading using sandbags can induce changes in movement of the upper extremities independently and contribute to functional rehabilitation through resistance training.

• PNF and Movement
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• v.13 no.1
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• pp.9-16
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• 2015

Purpose: This study aimed to examined the effects of upper and lower limb coordinated exercise of proprioceptive neuromuscular facilitation (PNF) on static and dynamic balance ability. Methods: The subjects of this study were 18 patients who had been diagnosed with a stroke and hospitalized and who had received rehabilitation treatment at D rehabilitation hospital located in J city. They were randomly and equally assigned to a PNF upper and lower limb coordinated exercise group and an ordinary central nervous system development and treatment group, and they conducted exercises for eight weeks. They carried out exercise three times per week, for 30 minutes per each time. After each four minutes of exercise, each participant was given a and rest for one minute after exercise for four minutes was given. In order to test the subjects' static and dynamic balance ability and their dynamic balance ability, frailty and injuries,: a cooperative studyies of intervention techniques (FICSIT-4) test, a four- step square test (FSST), a timed up and go test (TUG), and a TWT3M tests wasere conducted before and after the exercise. Descriptive statistics were taken for the general characteristics of the subjects, and an independent t-test was conducted both before and after the exercise in order to examine differences between the two groups before and after the exercise were conducted. The A statistical significance level was set at p= 0.05. Results: In all the tests (of FICSIT-4, FSST, TUG, and TWT3M), both the experimental group and the control group saw more improved results, but the experimental group's results were significantly higher than those of the control group, and the size of the effects was larger in the experimental group than in the control group, with statistically significant results. Conclusion: PNF upper and lower limb coordinated exercise applied to chronic stroke patients produced brought significant results in static and dynamic balance ability. PNF and is considered as an important intervention program to improve stroke patients' balance ability.