• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4C
• /
• pp.229-238
• /
• 2006

Observed field behaviors are frequently different from the behaviors predicted in the design state due to several uncertainties involved in soil properties, numerical modeling, and error of measuring system even though a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits. In this study, genetic algorithms are applied to back-analyze the soil properties using the observed behavior of soft clay deposit composed of multi layers that shows complex consolidation characteristics. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of multi layered soft deposits. Example analyses for drainage-installed multi-layered soft deposits are performed to examine the applicability of proposed back-analysis method.

• Journal of Korean Neurosurgical Society
• /
• v.67 no.2
• /
• pp.209-216
• /
• 2024

Objective : Some patients with disc herniation who underwent discectomy complain of back pain after surgery and are unsatisfied with the surgical results. This study aimed to evaluate the relationship between preoperative disc height (DH), postoperative DH, and pain score 12 months after surgery in patients who underwent microdiscectomy for herniated lumbar disc. Methods : This study enrolled patients who underwent microdiscectomy at a medical center between January 2012 and December 2020. Patients with X-ray or computed tomography and pain score assessment (visual analog scale score) prior to surgery, immediately post-op, and at 1, 6, and 12 months after surgery were included. The DH index was defined as DH/overlying vertebral width. The DH ratio was defined as the postoperative DH/preoperative DH. Simple linear regression and multivariate linear regression analyses were applied to assess the correlation between DHs and leg pain scores 12 months after surgery. Results : A total of 118 patients who underwent microdiscectomy were included. DH decreased up to 12 months after surgery. The DH ratio at 1, 6, and 12 months after discectomy showed a significant positive correlation with the pain scores at 12 months after discectomy (1 month : p=0.045, B=0.52; 6 months : p=0.008, B=0.78; 12 months : p=0.005, B=0.69). Multivariate linear regression analysis revealed that the level of surgery, sex, age, and body mass index had no significant relationship with back pain scores after 12 months. Conclusion : In patients who underwent microdiscectomy, the DH ratios at 1, 6, and 12 months after surgery were prognostic factors for back pain scores at 12 months after surgery. Aggressive discectomy is recommended for lower postoperative DH ratios and Visual analog scale scores, leading to improved patient satisfaction.

• Steel and Composite Structures
• /
• v.35 no.3
• /
• pp.305-325
• /
• 2020

Beams of steel frame-tube structures (SFTSs) typically have span-to-depth ratios of less than five. This makes a flexural beam unsuitable for such an application because the plastic hinges at the beam-ends cannot be adequately developed. This leads to lower ductility and energy dissipation capacities of SFTSs. To address this, SFTSs with bolted web-connected replaceable shear links (SFTS-BWSLs) are proposed. In this structural system, a web-connected replaceable shear link with a back-to-back double channel section is placed at the mid-length of the deep beam to act as a ductile fuse. This allows energy from earthquakes to be dissipated through link shear deformation. SFTS and SFTS-BWSL buildings were examined in this study. Several sub-structures were selected from each designed building and finite element models were established to study their respective hysteretic performance. The seismic behavior of each designed building was observed through static and dynamic analyses. The results indicate that the SFTS-BWSL and SFTS have similar initial lateral stiffness and shear leg properties. The SFTS-BWSL had lower strength, but higher ductility and energy dissipation capacities. Compared to the SFTS, the SFTS-BWSL had lower interstory drift, base shear force, and story shear force during earthquakes. This design approach could concentrate plasticity on the shear link while maintaining the residual interstory drift at less than 0.5%. The SFTS-BWSL is a reliable resistant system that can be repaired by replacing shear links damaged due to earthquakes.

• Journal of muscle and joint health
• /
• v.16 no.1
• /
• pp.13-25
• /
• 2009

Purpose: The purpose of this study was to investigate the relationships between job stress and work-related musculo-skeletal symptoms among nurses working in general hospitals. Method: A descriptive correlational research design was utilized. The participants were 438 nurses currently working in 4 general hospitals. Data were collected from Jan 2007 to Feb 2007, with Korean Occupational Stress Scale(KOSS)-basic form, KOSHA code H-30 and a questionnaire for general characteristics. Descriptive statistics, t-test, ANOVA, multiple logistic regression analyses were utilized. Result: Most participants(90.4%) complained of work-related musculo-skeletal symptoms. However, symptomatic nurses satisfying NIOSH screening criteria(symptomatic nurses) were 66.9%(293 persons). The most complained body part was back(39.5%). shoulder(37.7%), leg and foot(36.5%), wrist and hand(21.7%), neck(18.7%), and arm(9.8%). The mean of total score of occupational stress was 51.11. In multiple logistic regression analyses, age, working posture and total score of occupational stress showed significant associations with back symptoms. Exercise and total score of occupational stress were significantly related with shoulder symptoms. Hours of daily house keeping and working posture were related with leg and foot symptoms. Marital status and working posture were related with wrist and hand symptoms. Working posture only showed significant relations with neck symptom. Marital status, hours of daily house keeping, shift work, working posture, and total score of occupational stress were related with the symptoms in the arm. In conclusion, job stress of nurses might be related with work-related musculo-skeletal symptoms.

• Korean Journal of Radiology
• /
• v.22 no.2
• /
• pp.225-232
• /
• 2021

Objective: To determine whether changes in the transiting nerve rootlet or its surroundings, as seen on MRI performed after lumbar hemilaminectomy, are associated with persistent postoperative pain (PPP), commonly known as the failed back surgery syndrome. Materials and Methods: Seventy-three patients (mean age, 61 years; 43 males and 30 females) who underwent single-level partial hemilaminectomy of the lumbar spine without postoperative complications or other level spinal abnormalities between January 2010 and December 2018 were enrolled. Two musculoskeletal radiologists evaluated transiting nerve rootlet abnormalities (thickening, signal alteration, distinction, and displacement), epidural fibrosis, and intrathecal arachnoiditis on MRI obtained one year after the operations. A spine surgeon blinded to the radiologic findings evaluated each patient for PPP. Univariable and multivariable analyses were used to evaluate the association between the MRI findings and PPP. Results: The presence of transiting nerve rootlet thickening, signal alteration, and ill-distinction was significantly different between the patients with PPP and those without, for both readers (p ≤ 0.020). Conversely, the presence of transiting nerve rootlet displacement, epidural fibrosis, and intrathecal arachnoiditis was not significantly different between the two groups (p ≥ 0.128). Among the above radiologic findings, transiting nerve rootlet thickening and signal alteration were the most significant findings in the multivariable analyses (p ≤ 0.009). Conclusion: On MRI, PPP was associated with transiting nerve rootlet abnormalities, including thickening, signal alterations, and ill-distinction, but was not associated with epidural fibrosis or intrathecal arachnoiditis. The most relevant findings were the nerve rootlet thickening and signal alteration.

• Korean Journal of Occupational Health Nursing
• /
• v.15 no.1
• /
• pp.14-29
• /
• 2006

Purpose: The purposes of this study were to survey the extent of pain and discomfort in the musculoskeletal system among visiting housekeepers, above all concerning neck, shoulder, back, wrist, knee, and arm pain and to find possible relations between symptoms and various working conditions. Method: A questionnaire was answered by 174 woman visiting housekeepers living in Kyeonggi-do and Seoul from December 1, 2003 to February 30, 2004. The symptoms of musculoskeletal system were coded by the pain index which illustrates the extent of the symptoms, and analyzed in view of NIOSH guideline and Kim, et. al.'s notion. Result: 1. As to the complaint rate of subjective musculoskeletal symptoms by body region, the figure was the highest for shoulder with 78.2%, followed by back with 66.7%, knee 53.6%, neck 56.3%, wrist 40.2%, and arm 29.2%, respectively. The logistic analysis showed shoulder pain and arm pain have no relation with working and health conditions, and back pain was significantly related to current health condition. In same way, knee pain and wrist pain were found to be mainly related to marital status. 2. Following the NIOSH guideline, the positive rate of subjective musculoskeletal symptoms was found out in following order: shoulder 69.5%, back 59.2%, knee 54%, neck 46%, wrist 32.8%, and arm 25.3%. To investigate the main cause of each disease, the symptoms were classified by pain index, where the value of more than 3 comes to the NIOSH case, and analyzed in term of complaint rate using discrete logistical method : shoulder pain was highly related to the housekeeping time after work, back pain was to current health condition and the heavy weight carrying and neck, wrist, arm pain were commonly related to the ordinary health condition. For knee pain, working speed was a main cause. 3. In view of Kim et. al.'s standard, where the pain index is over 7, the positive rate was showed in order slightly different from previous analyses : shoulder 33.3%. knee 29.9%, back 28.2%, neck 17.2%, wrist 17.2%, and 16.7%. From the logistical analysis, insufficient rest was shown as the main cause of shoulder, back, arm and wrist pain. For neck pain, ordinary health condition was mainly related. In case of knee pain, any apparent relation is not found. Conclusion: According to the logistic regression analysis of musculoskeletal system, there was strong suggestion that the less insufficient physical rest, the more significant disorder complaint. This means that the most musculoskeletal symptom among the visiting housekeepers can be prevented and cured by sufficient physical resting.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.11
• /
• pp.4956-4962
• /
• 2012

Among the various parts of automobile, automotive seat is the most fundamental item that ride comfort can be evaluated as the direct contact part with human body. Automotive seat must have the sufficient rigidity and strength at the same time with ride comfort. In this study, cushion frame and back frame at car seat are modelled with 3D. There are structural simulation analyses about 3 kinds of tests on torsion strength, vertical load strength and back frame strength. In the analysis result, the initial total deformation and the permanent total deformation has the maximum values of 5.4821 mm and 0.02539mm respectively at the torsion strength test of cushion frame. Total deformations at front and rear end parts of cushion frame become the values of 2.1159mm and 0.0606mm respectively at the test of vertical load strength of cushion frame. In case of more than this load, the maximum value of total deformation also becomes 3.1739mm. The maximum value of total deformation becomes 0.18634mm at 3 kinds of the strength tests on back frame. By the study result of no excessive deformation and no fracture cushion frame and back frame at automotive seat, the sufficient rigidity and strength to guarantee the safety of passenger can be verified.

• Journal of the Korean Society of Costume
• /
• v.51 no.4
• /
• pp.31-42
• /
• 2001

The purpose of this study was to develop a large representative data base for character goods marketing strategy. The study was to determine character name awareness in relation to segmented distribution regions and such demographic variables as sex and age. The author also analyzed preferred design. A total of 360 questionnaires were distributed and 359 reliable ones were used for statistical analysis. A SAS statistical package including frequency tables and Chi square test and factor analysis and Kendall′s relation analyses was used. The results are as follow : character name awareness involves "character name decognition" based on asking subjects to identify character names from 50 given names. "Tele-tubbies" was found to be a dominant commercial character name as a result of the recognition test, and "Sailer-moon" was found to be a dominant animation character goods as a result of the recognition test. Character recognition was significantly different in the segmented distribution legions, three age groups and different sex groups. People considered design first in purchasing any character goods, and they considered color second in purchasing them. The most favored part of garment far character to be stitch to was the center front in the T-shirt/dress shirt, the center back in the Jumper/jacket, back pocket in the trousers/skirt. The results of a Chi-square test showed that preferred part in the trousers/skirt of character was related with age variables.

• International Journal of Fluid Machinery and Systems
• /
• v.3 no.3
• /
• pp.235-244
• /
• 2010

Recent studies on the moment whirl due to leakage flow in the back shroud clearance of hydro-turbine runners or centrifugal pump impellers are summarized. First, destabilizing effect of leakage flow is discussed for lateral vibrations using simplified models. Then it is extended to the case of whirling motion of an overhung rotor and the criterion for the instability is obtained. The fluid moment caused by a leakage clearance flow between a rotating disk and a stationary casing was obtained by model tests under whirling and precession motion of the disk. It is shown that the whirl moment always destabilizes the whirl motion of the overhung rotor while the precession moment destabilizes the precession only when the precession speed is less than half the rotor speed. Then vibration analyses considering both whirl and precession are made by using the hydrodynamic moments determined by the model tests. For larger overhung rotors, the whirl moment is more important and cause whirl instability at all rotor speed. On the other hand, for smaller overhung rotors, the precession moment is more important and cancels the destabilizing effect of the whirl moment.

• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.1
• /
• pp.100-110
• /
• 1999

The objectives of this study are twofold: (1) to evaluate the cockpit of three Korean air force fighters such as F-4, F-5, and F-16 in an ergonomic perspective and (2) to measure the musculoskeletal discomfort of the fighter pilots. For the study, 369 air force pilots from 7 squadrons were surveyed. The study shows that the cockpit design of F-16 is superior to the others. However, F-4 is the worst among them. Statistical analyses reveal that the seat in the cockpit raised the most complaints, regardless of types of fighter planes. The main problems with the seat included inappropriate designs of the backrest angle, seat cushioning, and parachute harness. Also frequently cited are various control switches, control stick, rudder pedal, and the throttle. That these items lack human integration is found in remote positions and improper dimensions. The implications of these findings are discussed. The self-reported musculoskeletal complaints show that the main discomfort is on the back and neck. Also, the buttocks, shoulders, and the legs/knees are common sites of discomfort. A stepwise regression analysis shows that the back discomfort, is mainly caused by the use of the seat, rudder pedal, control stick, and switches. A Spearman rank correlation coefficient test also reveals that job dissatisfaction of the pilots is related to the complaints with the cockpit and musculoskeletal discomfort. These findings suggest that more comprehensive studies for cockpit design in the aspects of functional anthropometry of Korean pilots are needed to reduce the musculoskeletal discomfort.