• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.479-484
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• 2000

The reliable estimation of the system parameters and the accurate prediction of the system behavior are important to design tunnel safely and economically. Therefore, the back analysis using the field measurements data is useful to evaluate the geotechnical parameter for tunnel. In the back analysis method, the selection of initial value and uncertainty of field measurements influence significantly on the analysis result. In this paper, to overcome uncertainty of field measurements, we performed the back analysis using the displacement data gained at each step of excavation and support.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.43.1-43.1
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• 2010

In the crystalline silicon solar cells, the full area aluminum_back surface field(BSF) is routinely achieved through the screen-printing of aluminum paste and rapid firing. It is widely used in the industrial solar cell because of the simple and cost-effective process to suppress the overall recombination at the back surface. However, it still has limitations such as the relatively higher recombination rate and the low-to-moderate reflectance. In addition, it is difficult to apply it to thinner substrate due to wafer bowing. In the recent years, the dielectric back-passivated cell with local back contacts has been developed and implemented to overcome its disadvantages. Although it is successful to gain a lower value of surface recombination velocity(SRV), the series resistance($R_{series}$) becomes even more important than the conventional solar cell. That is, it is a trade off relationship between the SRV and the $R_{series}$ as a function of the contact size, the contact spacing and the geometry of the opening. Therefore it is essential to find the best compromise between them for the high efficiency solar cell. We have investigated the optimal design for the local back contact by using PC1D simulation.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.196-201
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• 2019

The purpose of this study is to identify the effects of the apply of lumbar stabilization exercises and lumbar strengthening exercises using Medx machine on back functions such as static balance, lumbar reposition sense, and back pain(VAS) in chronic low back pain. This study divided 30 chronic low back pain patients who experienced only lumbar back pain(male: 5, female: 10) into a lumbar stabilization exercise group and a complex exercise group, and then performed their respective exercise programs for three times a week over a 8-week period. The lumbar static balance, lumbar reposition sense, and lumbar back pain were measured using a pair t-test within each group, and were also compared between two groups using an independent t-test. The results of the present study were as follows: Both groups exhibited statisti cally significant increases after performing their own exercise program in the static balance, lumbar reposition sense, and lumbar back pain(p<.05). However, the comparison of two groups confirmed that the complex exercise group resulted in greater effects than the lumbar stabilization exercise group(p<.05). In conclusion, muscle strengthening and stabilization exercises in chronic low back pain patients are considered to not only relieve back pain, but also improve various back functions.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.2
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• pp.83-91
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• 2020

PURPOSE: Postural and structural asymmetry due to muscle imbalances around the lower back and pelvis are the causes of back pain. Muscle imbalances in patients with chronic low back pain affect the pelvic tilt and movement, and it is necessary to assess the pelvic movement ability using the appropriate tools to determine the mediating effects of lower back pain. This paper reports the reliability and validity of the Sensbalance Therapy Cushion (STC) for pelvic movement and proprioception. METHODS: In this study, the Wii balance board (WBB) was used as a golden standard for pelvic movement measurements. FABQ, KODI, Myovision, and Pelvic movement were measured in 50 patients with chronic low back pain. The correlation between the lower-back muscle activity and pelvic movement was checked. The pelvic movement parameter was measured twice to determine the intra-rater reliability. RESULTS: The STC showed high test-retest reliability in the pelvic tilt measurements (ICC = .672 - .809). The test-retest reliability of proprioception measurements (ICC = .588 - .859) and reaction time measurements (ICC = .542 - .836) were also high. The relationship between the WBB and STC showed a significant positive correlation with the pelvic tilt test (p < .01). The posterior pelvic tilt and lower-back muscle activity showed a significant negative correlation (p < .01). The pelvic left tilt and lower-back muscle activity showed a significant negative correlation (p < .05). CONCLUSION: The results revealed the high reliability and validity of the STC. Therefore, the STC can be used as an objective measuring device for evaluating pelvic tilt, proprioception, and reaction time in low back pain patients.

• Korean Journal of Occupational Health Nursing
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• v.14 no.1
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• pp.44-55
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• 2005

Purpose: The purpose of this study was to describe the current status of work-related back pain among nurses in the U.S. Method: Literature review and website searching were conducted. Key words as 'nurse and back pain (or back injury)' were used in searching the Medline, NIOSHTIC-2and reference list of selected studies. Total studies were selected of which subjects were nurses working in the U.S., and published since 1970. Results: Though there was variation in the measurement among studies, the prevalence rate of back pain among nurses in the U.S. could be estimated about 50%. Risk factors were confirmed as the frequency of patient lifting, ward, nursing shortage, overtime, work shift, stress on physical demand, but age and work experiences showed the inconsistent relation. It has been well known that educational approach is not enough to prevent back pain. Intervention studies to apply the ergonomic approach using mechanical devices reported the effects, but the devices were less diverse than European countries or Canada. The study for lifting team was rare. Federal government developed only the guideline for nursing home that had no legal obligation. As a professional nursing organization, ANA has been trying to educate and advocate for "No lift policy" since 2003. Meanwhile, two trade unions of nurses made efforts to establish the law strengthening the responsibility of health care facilities. Conclusion: The research and policy development will be needed to prepare to rapid increase of back pain among Korean nurses.

• The Korean Journal of Rehabilitation Nursing
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• v.11 no.1
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• pp.5-12
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• 2008

Purpose: The purpose of this study was to identify the uses of complementary and alternative therapies(CAT), pain, and quality of life(QOL) in patients with chronic back pain. Method: A descriptive survey was conducted using convenient sample. One hundred sixty two patients with chronic back pain participated in this study. Types and satisfaction of CAT, pattern of back pain, and QOL were investigated. Result: 83.3% of all participants reported in the use of CAT. The most common types of CAT used were acupuncture and half-bath. Yoga were the most high satisfaction among the types. The mean score of back pain was 4.12, QOL was 3.10, that was mostly low score. There was no significant difference back pain and QOL between CAT user and nonuser. Correlation with satisfaction of CAT according the most using types were a negative correlation with back pain and a positive correlation with QOL. Conclusion: These result indicate that the mostly patients with back pain feels the satisfaction of CAT use. It is important that provide the obvious information about CAT which can be helpful to patient.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.246-251
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• 2012

This paper proposes a new position compensation method for misaligned Hall-effect sensors of BLDCM(Brushless DC Motor). If the Hall-effect sensors are installed at wrong position, the exact rotor position cannot be obtained. Therefore, when the BLDCM is controlled with this wrong position, the torque ripple can be increased and the average torque also decreases. The back-EMF of BLDCM can be obtained by using the voltage equation and by multiplying the back-EMF constant and rotor speed. At a constant speed, the estimated back-EMF by using the multiplication of the back-EMF constant and rotor speed is constant, but the estimated back-EMF from the voltage equation decreases at the commutation point because the line-to-line back-EMF of two conducting phases is start to decrease at this point. Therefore, by using the difference between these two estimated back-EMFs, the commutation point of the phase current can be determined and position compensation can be carried out. The proposed position correction method doesn't require additional hardware circuit and can be easily implemented. The validity of the proposed position compensation method is verified through several experiments.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.1
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• pp.24-30
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• 2009

The purpose of this study is to investigate the fatigue strength in accordance with back plate of butt welded specimens. Fatigue life of butt welded specimens was presented for determining the effect of back plates in terms of fatigue strength. As a results, fatigue strength of butt welded specimens with steel back plate show a decrease as compared against the butt welded specimens with ceramic back plate. Compared with the fatigue strength with respect to the existence of steel back plate, the specimens without back plate were much higher than the specimens with back plate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.643-652
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• 1998

This paper presents the characteristics of a relay station antenna with the newly designed back-plate structure which is composed of the U-shaped metal plate for suppression of the back lobe by edge diffraction. The back lobe level of the conventional type was about -20 dB in the -z direction ( 180 ) . In order to improve the characteristics, the U-shaped mesh type metal plate is considered, where the design condition of the model antenna satisfies the wide null point angle range with the back lobe level of -30 dB below in the -z direction. The design parameters with the minimum back lobe level such as the dipole length, the distance between dipole elements and the back plate size have been found by using the released NEC Win Pro code. The calculated and measured back lobe Bevel of model antenna have been obtained 48.48 dB and -45 dB at 325 MHz, respectively.

• Journal of the Korean Society of Physical Medicine
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• v.1 no.1
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• pp.23-36
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• 2006

Purpose : The purpose of this study was to evaluate the effects of back muscle stretching on the flexibility of spinal column. Methods : The subjects were consisted of healthy adults (18 of females, 22 males ; mean aged 21.83) from 18 to 29. All subjects randomly assigned to the control group, back muscle stretching group. back muscle stretching group received back muscles stretching for 20 minutes per day and 3 times a week during 3 week period. Spine motion analyzer (Spinal Mouse) was used to measure the flexibility of spinal column. All measurement of each subjects were measured at pre-experiment, after 10 days, and after 21 days. Results : The results of this study were summarized below 1. The sacral tilt angle of the hip joint of control group, back muscle stretching group was no significantly differences at pre-experiment and after 10 days(p>0.5), but differency of each group occurred at after 21 days(p<0.5). the sacral tilt angle significantly increased at the back muscle stretching group rather than the control group. 2. The thoracic vertebral tilt angle of the control group, back muscle stretching group was no significantly differences at pre-experiment, after 10 days, after 21 days(p>0.5). 3. The lumbar vertebral tilt angle of the control group, back muscle stretching group was no significantly differences at pre-experiment, after 10 days, after 21 days(p>0.5). 4. The spinal tilt angle of control group, back muscle stretching group was no significantly differences at pre-experiment and after 10 days(p>0.5), but differency of each group occurred at after 21 days(p<0.5). the spinal tilt angle significantly increased at the back muscle stretching group rather than the control group(p>0.5). 5. The length of the spinal column of control group, back muscle stretching group was no significantly differences at pre-experiment and after 10 days (p>0.5), but differency of each group occurred at after 21 days(p<0.5). the length of the spinal column significantly increased at the back muscle stretching group rather than the control group(p<0.5). Conclusion : These data suggests that 3-week back muscle stretching improved the flexibility of sacrum, spinal column, and also improved spinal column lengthening. Additional randomized controlled trials to more fully investigate treatment effects and factors that may mediate these effects are needed.