• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.77-78
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• 2016

본 논문에서는 양방향 전력공급이 가능한 3상 Back to Back 컨버터에 필요한 여러 가지 제어 기술들을 살펴보고 시뮬레이션을 통해 제어 알고리즘의 타당성을 분석하며, 입, 출력 전압, 전류 등 파형을 관찰하고 전력을 가변시킬 때 나타나는 3상 계통연계형 Back to Back 컨버터의 동특성을 개선하는 방법을 알아본다.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.69-76
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• 2020

Since the mechanically stabilized earth walls have a form of retaining wall compatible with a narrow section, the geogrid overlaps according to the separation distance between the walls. There is a problem that the overall behavior may occur in the state of being integrated with the stress change due to the interaction of the geogrid. Therefore, a careful approach is required at the design stage, but there are currently no design criteria or guidelines in Korea. This study investigated the optimal reinforcement length ratio according to the retaining wall width to height ratio (width to height ratio, Wb/H) for these back-to-back mechanically stabilized earth walls. Retaining wall width ratio is 1.1H, 1.4H, 1.7H, 2.0H for Case II of the FHWA design standard, and the height is 3.0 m, 5.0 m, 7.0 m, and 10.0 m, which are most commonly applied. Through numerical analysis, the appropriateness of the FHWA design standard and the optimal reinforcement length ratio according to the height of the retaining wall and the width of the retaining wall were proposed.

• Physical Therapy Korea
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• v.8 no.1
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• pp.59-75
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• 2001

The purposes of this study were to investigate risk factors of low back pain in civil airmen and to use this information as basis for the back rehabilitation. Subjects of this study were randomly selected 276 civil airmen who had been employed at four airports in Seoul. These data were analyzed by $X^2$ test, t-test, ANOVA, and multiple logistic regression using SAS. The results were as follows: 1) The prevalence of low back pain among 276 civil airmen was 64.9%. 2) The most common cause of low back pain was load lifting (stewardess), long sitting (aircrew A), and long sitting plus training (aircrew B). 3) There were no statistically significant associations among age, height, body weight, and low back pain. 4) No statistically significant relationships were found among the average monthly working time, total working time, average monthly rest time, working year and low back pain. 5) There was statistically significant relation ship between abnormal posture and low back pain (p<.01). 6) There was statistically significant relation ship between fatigue and low back pain among stewardess and aircrew B. 7) There was a statistically significant relationship between job satisfaction and job-related stress (p<.05). 8) In stewardess, higher satisfaction score was associated with less likelihood of low back pain (odds ratio = .80). The results of this study indicate that civil airmen developed chronicity of low back pain due to unfit seat, poor habitual posture, fatigue symptom, and stress or other risk factors. Therefore, there is a need to improve the working environment for the prevention of posture-related low back pain.

• The Research Journal of the Costume Culture
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• v.28 no.1
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• pp.1-14
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• 2020

This study is based on a representative body shape drawn from previous studies that classify adult male torso shapes. In this study, a design method is proposed by developing a tight-fit pattern that can be easily developed into various items and designs using the body surface development figure. This is obtained by converting the 3D body shape of the model representing the representative body shape. The specific design method was conducted as follows. Actual measurement values were used for waist back length, waist-to-hip length, shoulder length. The scye depth was determined as C/4-1.7 cm, and the front and back Interscye was set at (1/2 × actual measurements)-0.2 cm. The front-back neck breadth was set to (1/5 × base neck circumference)-1.3 cm and (1/5 × base neck circumference) cm. The front-back neck depth was set to (1/5 × base neck circumference)-1.2 cm and 3.5 cm. Front chest circumference was C/4-1 (front-back difference)cm; (1/4 × back chest circumference) was C/4 + 1 (front-back difference) + 0.3 (dart amount) cm. Front waist circumference was W/4-0.2 (front-back difference) + 2.2 (dart amount) cm; back waist circumference was W/4 + 0.2 (front-back difference) + 2.5 (dartamount) cm; front hip circumference was H/4 + 0.2 (ease) + 0.2 (front-back difference) cm; and back hip circumference was H/4 + 0.2 (ease)-0.2 (front-back difference) cm; Front droop was 1.6 cm. The newly developed tight-fit pattern is expected to be of great use as a basis for garment construction.

• Journal of Korean Physical Therapy Science
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• v.2 no.4
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• pp.817-822
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• 1995

Even though back pain therapy has greatly improved as spinal bio-mechanics is introduced, many patients still have difficulties due to low back pain. At the initial therapeutic stage, the aim of rehabilitation therapy for low back pain is pain control, but, at the later therapeutic stage, the prime aims are to reduce the late complication and to prevent the recurrence of low back pain. Accurate diagnosis should be a first step before any therapy is planned. Thus, accurate physical, neurologic, E.M.G. and radiologic tests are required to give prescription for therapeutic exercise to the patients. In addition to this, the roles of theraphists and therapeutic exercise should be re-evaluated after the therapeutic exercise is performed. Fist of all, the most important things are to educate the patients to understand the low back pain and to let the patients join the therapeutical planning. 1. Bed rest and muscle relaxing exercise for releasing the muscle tention are required for the treatment of acute low back pain. An active exercise is recommended rather than a passive exercise. If the therapeutic exercise depravate the low back pain, the exercise should be immediately terminated and the therapeutical exercise should be replanned. 2. For the treatment of the chronic back pain, stretching exercise and para-spinal muscle strengthening exercise should be performed steadily and actively to prevent the recurrence of low back pain and the low back injury due to minor damage. The patients should be educated to do proper exercise and to maintain good posture in everyday life. 3. As the low back pain is released and the body function is recovered, control of whole body function is necessary. Swiming, bicycling and walking for $30\sim40$ minutes a day and $3\sim4$ days a week are recommended. Other exercise could be recommended depending on the patients condition.

• Journal of Mechanical Science and Technology
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• v.14 no.1
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• pp.84-92
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• 2000

A new bounce back boundary method of the second order in error is proposed for the lattice Boltzmann fluid simulation. This new method can be used for the arbitrarily irregular lattice geometry of a non-slip boundary. The traditional bounce back boundary condition for the lattice Boltzmann simulation is of the first order in error. Since the lattice Boltzmann method is the second order scheme by itself, a boundary technique of the second order has been desired to replace the first order bounce back method. This study shows that, contrary to the common belief that the bounce back boundary condition is unilaterally of the first order, the second order bounce back boundary condition can be realized. This study also shows that there exists a generalized bounce back technique that can be characterized by a single interpolation parameter. The second order bounce back method can be obtained by proper selection of this parameter in accordance with the detailed lattice geometry of the boundary. For an illustrative purpose, the transient Couette and the plane Poiseuille flows are solved by the lattice Boltzmann simulation with various boundary conditions. The results show that the generalized bounce back method yields the second order behavior in the error of the solution, provided that the interpolation parameter is properly selected. Coupled with its intuitive nature and the ease of implementation, the bounce back method can be as good as any second order boundary method.

• Journal of Korean Public Health Nursing
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• v.26 no.3
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• pp.504-517
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• 2012

Purpose: The aim of this study was to investigate gender differences in risk factors and sleep, depression, and mobility of Korean elderly with and without low back pain and sciatica. Methods: Data were derived from the 2011 Korean National Survey on Older Adults. Participants included 10,674 community-dwelling elderly. The group of elderly subjects with low back pain and sciatica and the group of elderly subjects without low back pain and sciatica were compared according to gender. Result: Age, monthly income, exercise, arthritis, osteoporosis, and providing caring support were significant risk factors for low back pain and sciatica in elderly male subjects. On the other hand, monthly income, living arrangement, arthritis, osteoporosis, providing caring support, and television watching time were significant risk factors in elderly female subjects. Significant differences in depression and mobility according to low back pain and sciatica were observed in both genders. Conclusion: Risk factors for low back pain and sciatica in elderly differed according to gender. Low back pain and sciatica showed an association with depression and mobility. These findings should be considered in planning for nursing intervention for low back pain and sciatica.

• Journal of Korean Neurosurgical Society
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• v.46 no.5
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• pp.443-450
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• 2009

Objective : We estimated the number of Korean adults with back pain and evaluated population-based associated factors of back pain from a representative sample data from the Fourth Korea National Health and Nutrition Examination Survey. Methods : The number of Korean adults who experienced back pain (experienced patients), those who experienced back pain lasting for three or more months during the past year (chronic patients), and those who were currently suffering from back pain (current patients) were estimated by analyzing the data from the fourth Korea National Health and Nutrition Examination Survey conducted in 2007 using surveyfreq procedure of the SAS statistical package. Population-based odds ratios for being experienced, chronic, and current patient according to demographic (age and gender), socioeconomic (education and occupation), and lifestyle factors (smoking, drinking, and exercise) were estimated using surveylogistic procedure. Results : It was estimated that there were 5,554,256 (proportion, 15.4%; 95% CI, 4,809,466 - 6,299,046) experienced patients, 2,060,829 (5.7%; 1,557,413-2,564,246) chronic patients, and 3,084,188 (8.5%; 2,600,197 - 3,568,179) current patients among 36,107,225 Korean adults aged 20-89 years in 2007. Each of explanatory variables was significantly associated with at least one of the response variables for back pain. Conclusion : Based on our study results, further efforts to investigate epidemiology of back pain, to evaluate associated factors, and to improve treatment outcomes are needed.

• Journal of Korean Library and Information Science Society
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• v.38 no.4
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• pp.257-276
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• 2007

Back-of-book-style indexes have a similar function as back-of-book indexes. The best advantage o4 back-of-book-style indexes for Information access on the web is to give direct access to specific subjects of interest. Though back-of-book-style indexes are alphabetically arranged as back-of-book indexes, they have linked index entries to contents on the site by using a anchor tag of HTML. In this research, I have created back-of-book-style indexes in two separated ways, by hand-crafted and semi-automatic Indexing. We have utilized back-of-book-style indexes, that is similar to back-of-book index of traditional information organization method of library and information science, in library circumstances.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.410-415
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• 2007

The optimization of back pressure chamber is one of the most important factors in designing scroll compressors, because it has a great influence on the efficiencies and other design parameters. The design process can be divided into 2 parts. One is obtaining the optimum pressure of the chamber and keeping it in constant value. And the other is finding out the minimum inflow rate of medium with which back pressure chamber is filled. In this study we are focused on the first step. At first we added a simple structure that could change back pressure without reassembling compressor. It makes the optimum back pressure be obtained. And then we devised an equipment that the back pressure control valve assembly could be independently tested with. A spring was redesigned to decrease stiffness variation. And sealing mechanism of back pressure control valve was improved to more effective way. As a result it was verified in a real mode test that back pressure variation could be stabilized within 2.3% when discharge pressure and operating frequency varied. And the integrated structure of back pressure control valve is expected to contribute to an effective manufacturing process.