• 대한물리의학회지
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• 제9권3호
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• pp.333-338
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• 2014

PURPOSE: The purpose of this study was to investigate any changes in abdominal muscle activity after curl-up and jack-knife exercisse using a sling and swiss-ball. METHODS: Sixteen asymptomatic subjects were randomly assigned into either a sling exercise group (SG) or swiss-ball exercise group (SBG). Subjects performed curl-up and jack-knife exercise using sling and swiss ball. Activity of abdominal muscles (rectus abdominis and external oblique) was assessed using surface electromyography (EMG) and normalized maximal voluntary isometric contraction (MVIC) before and after exercises. The significance of differences between the SG and the SBG was evaluated by analysis of covariance (ANCOVA). RESULTS: There was an increase in activity of all abdominal muscles after the curl-up and jack-knife exercises for 6 weeks. However, there was not a significant difference between the SG and the SBG after curl-up exercise (p>.05). There was also not a significant difference between the SG and the SBG after Jack-knife exercise (p>.05) except for the right external oblique muscle (p<.05). CONCLUSION: Exercises on an unstable surface using a sling and swiss ball are effective ways of abdominal muscle exercise.

• 국제물리치료학회지
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• 제11권3호
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• pp.2102-2106
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• 2020

Background: Static hamstring stretching exercises have been widely used to improve flexibility of the hamstring muscles. However, few studies have examined the influence of standing static hamstring stretching (e.g., jack-knife stretching) on movements of the lumbopelvic-hip complex. Objectives: To examine the short-term effects of jack-knife stretching on movements of the lumbopelvic-hip complex. Design: Case series. Methods: Fourteen participants with hamstring tightness (8 male, 6 female) were recruited. Participants performed jack-knife stretching for 150 s. Before and after stretching, participants performed the finger-to-floor distance (FFD), sit and reach (SRT), active knee extension (AKE), passive straight leg raising (PSLA), and active straight leg raising (ASLR) tests as well as pelvic tilt while standing to identify the effects of stretching. Results: There were significant improvements in the FFD, SRT, AKE, PSLA, and ASLR tests after stretching. However, pelvic tilt angle while standing did not significantly change. Conclusion: Jack-knife stretching can be a useful exercise to improve flexibility of the hamstring muscles, but not pelvic alignment while standing.

• The Journal of Korean Physical Therapy
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• 제25권3호
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• pp.149-154
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• 2013

Purpose: Spinal instability due to weakness of abdominal muscles is one of the major causes that induces low back pain (LBP). The purpose of this study was to investigate any differences in abdominal muscle activity during curl up, roll out, and jack knife exercises using a swiss-ball or sling. Methods: Twenty healthy subjects were randomly assigned into either a swiss-ball exercise group (SBEG) or a sling exercise group (SEG). Subjects performed curl up, roll out and jack knife exercises using the swiss ball or sling. Activity of abdominal muscles (rectus abdominis and external oblique muscle) was assessed using surface EMG and normalized maximal voluntary isometric contraction (MVIC). The significance of differences between the sling exercise group and the swiss-ball exercise group was evaluated by the independent t-test. Results: These Results indicated that activities of rectus abdominis on right and left of the SEG during the curl up exercise were significantly greater than the SBEG. During the roll out exercise, activity of the abdominal muscle was not significantly different between the SEG and SBEG. In addition, during the jack knife exercise, activities of the right rectus abdominis and left external oblique muscle in the SEG were significantly greater than the SBEG. Conclusion: In conclusion, activity of the abdominal muscles was maximized when curl up and jack knife exercise were performed using the sling rather than the swiss-ball. Therefore, if increased activation of the abdominal muscle is the goal of an exercise program, curl up and jack knife exercises may be useful.

• The Korean Journal of Pain
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• 제23권3호
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• pp.190-197
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• 2010

Background: Conventional spinal saddle block is performed with the patient in a sitting position, keeping the patient sitting for between 3 to 10 min after injection of a drug. This amount of time, however, is long enough to cause prolonged postoperative urinary retention. The trend in this block is to lower the dose of local anesthetics, providing a selective segmental block; however, an optimal dose and method are needed for adequate anesthesia in variable situations. Therefore, in this study, we evaluated the question of whether only 1 min of sitting after drug injection would be sufficient and safe for minor anorectal surgery. Methods: Two hundred and sixteen patients undergoing minor anorectal surgery under spinal anesthesia remained sitting for 1 min after completion of subarachnoid administration of 1 ml of a 0.5% hyperbaric bupivacaine solution (5 mg). They were then placed in the jack-knife position. After surgery, analgesia levels were assessed using loss of cold sensation in the supine position. The next day, urination and 11-point numeric rating scale (NRS) for postoperative pain were assessed. Results: None of the patients required additional analgesics during surgical manipulation. Postoperative sensory levels were T10 [T8-T12] in patients, and no significant differences were observed between sex (P = 0.857), height (P = 0.065), obesity (P = 0.873), or age (P = 0.138). Urinary retention developed in only 7 patients (3.2%). In this group, NRS was $5.0{\pm}2.4$ (P = 0.014). Conclusions: The one-minute sitting position for spinal saddle block before the jack-knife position is a safe method for use with minor anorectal surgery and can reduce development of postoperative urinary retention.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 1997년도 수산관련공동학술대회발표요지집
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• pp.171-172
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• 1997

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 1998년도 수산관련공동학술대회발표요지집
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• pp.141.1-142
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• 1998

• 동력기계공학회지
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• 제11권2호
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• pp.58-63
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• 2007

Vehicular safety and occupant injury have been of considerable interest to the public. The dynamic response of an articulated vehicle is different from that of single body vehicle due to its geometric and inertia properties. Articulated vehicles have the tendency to jackknife if they lose driving safety. Influence of factors for driving safety of an articulated vehicle(Tractor-Semitrailers) has been analysed by the EDVTS, a kinetic analysis program for an articulated vehicle. EDVTS permits an analyst to investigate the effect of many variables in a short period of time, and enables to obtain an accurate explanation of driving safety. The factors used in the analysis include the load, friction coefficient, tire flat, increase of braking force, and trailer geometry. Based on the results, the articulation angle and driving safety were influenced remarkably by the load, coefficient of friction, increase of braking force. However, trailer geometry, such as length and width, did not affect articulation angle and driving safety

• Management Science and Financial Engineering
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• 제9권1호
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• pp.4-10
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• 2003

We introduce a new estimator of the uncertainty of a jackknife estimate of standard error: the jack-knife-after-jackknife (JAJ). Using Monte Carlo simulation, we assess the accuracy of the JAJ in a variety of settings defined by statistic of interest, data distribution, and sample size. For comparison, we also assess the accuracy of the jackknife-after-bootstrap (JAB) estimate of the uncertainty of a bootstrap standard error. We conclude that the JAJ provides a useful new supplement to Tukey's jackknife, and the combination of jackknife and JAJ provides a useful alternative to the combination of bootstrap and JAB.

• Management Science and Financial Engineering
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• 제9권1호
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• pp.1-10
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• 2003

We introduce a new estimator of the uncertainty of a jackknife estimate of standard error: the jack-knife-after-jackknife (JAJ). Using Monte Carlo simulation, we assess the accuracy of the JAJ in a variety of settings defined by statistic of interest, data distribution, and sample size. For comparison, we also assess the accuracy of the jackknife-after-bootstrap (JAB) estimate of the uncertainty of a bootstrap standard error. We conclude that the JAJ provides a useful new supplement to Tukey's jackknife, and the combination of jackknife and JAJ provides a useful alternative to the combination of bootstrap and JAB.

• Journal of the Korean Data and Information Science Society
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• 제24권4호
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• pp.885-893
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• 2013

This paper considers Bayes estimations of the small area means under Fay-Herriot model with measurement errors. We provide empirical Bayes predictors of small area means with the corresponding jackknifed mean squared prediction errors. Also we obtain hierarchical Bayes predictors and the corresponding posterior standard deviations using Gibbs sampling. Numerical studies are provided to illustrate our methods and compare their eciencies.