• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.275-276
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• 2002

Active-head sliders with a unimorph piezoelectric actuator for flying height control were experimentally evaluated. It was found that the normalized stroke of the actuator is 5.2 to 6 nm/V/mm without flying over the disk. However, the normalized adjustment range of flying height is about 1.6 nm/V/mm when the active-head slider is flying over the disk. This value is smaller than the measured value when the slider is not flying, because of the air pressure generated at the active pad when the pad approaches the disk surface.

• Journal of the Ergonomics Society of Korea
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• v.17 no.3
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• pp.1-11
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• 1998

Focuses of this study are to investigate the usage status of head-restraint system(H/R) in usual driving and to simulate usage conditions of H/R at rear-end crashes. The usage of H/R was categorized into five classes according to the height and distance from occupant's head ; Large-$90^{\circ}$ H/R for enough height and short distance. Large-$70^{\circ}$ H/R for enough height and long distance. Small-$90^{\circ}$ H/R for low height and short distance. Small-$70^{\circ}$ H/R for low height and long distance. and No H/R. Then. these five conditions were tested to find out the degree of neck injuries by using a car-crash simulation package, DYNAMAN. Results from the investigation of H/R usage show that most of drivers(60%) have Small-$70^{\circ}$ H/R for low height and long distance. Results from the simulation performed at 15mph and 30mph show that: 1) at 15 mph, there is a possibility for neck injury in Small-$90^{\circ}$ H/R and Small-$70^{\circ}$ H/R. 2) at 30 mph. there is a high possibility of death in Small-$70^{\circ}$ H/R and Small-$90^{\circ}$ H/R.

• The Research Journal of the Costume Culture
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• v.12 no.6 s.53
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• pp.933-944
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• 2004

This study was aimed to provide the fundamental and various measurement data of the head and face for male children. Two hundred forty one male children, aged nine to twelve years, participated for this study. The 31 regions on the head and face of the subjects were directly measured by the expert experimenters. Through factor analysis, the six factors were extracted upon factor scores and those factors comprised $67.47\%$ for the total variances. The first factor was described the general height elements for the mouth and the environs of the mouth. The second factor was described the general height around the nose, forehead and eyes. The third factor was described the height of the ear environs. The forth factor contained the length around the sinciput to the occiput, the head thick and the head circumstance. The fifth factor was described the general width of the outer head and the corner of the eyes. The last factor contained the depth of the mouth and nose. Four clusters as their head and face shape were categorized using six factor scores by cluster analysis. Type 1 was characterized by the shortest head and face width, surface length and girth, and the shorter length of head, but the highest position of chin, philtrum, upper lip. Type 2 was characterized by the shortest head and face length and thickness, and the lowest position of the forehead, eye, nose, mouth, ear environs, but that had wider width of head and face. Type 3 was characterized by the longest and the widest head and face type, and the highest position of the mouth. Type 4 was characterized by longer length of head and face, and the widest head girth and largest head thickness, and the highest position of the forehead, eye, nose environs. And this type had the widest width of nose and mouth, and the longest head surface length.

• Asian Spine Journal
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• v.12 no.6
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• pp.1053-1059
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• 2018

Study Design: Retrospective review. Purpose: To detect the effect of cannulated (poly-axial head) and solid (mono-axial head) screws on the local kyphotic angle, vertebral body height, and superior and inferior angles between the screw and the rod in the surgical management of thoracolumbar fractures. Overview of Literature: Biomechanics studies showed that the ultimate load, yield strength, and cycles to failure were significantly lower with cannulated (poly-axial head) pedicle comparing to solid core (mono-axial head). Methods: The medical charts of patients with thoracolumbar fractures who underwent pedicle screw fixation with cannulated or solid pedicle screws were retrospectively reviewed; the subjects were followed up from January 2011 to December 2015. Results: Total 178 patients (average age, $36.1{\pm}12.4years$; men, 142 [84.3%]; women, 28 [15.7%]) with thoracolumbar fractures who underwent surgery and were followed up at Hamad Medical Corporation were classified, based on the screw type as those with cannulated screws and those with solid screws. The most commonly affected level was L1, followed by L2 and D12. Surgical correction of the local kyphotic angle was significantly different in the groups; however, there was no significant difference in the loss of correction of the local kyphotic angle of the groups. Surgical correction of the reduction in the vertebral body height showed statistical significance, while the average loss of correction in the reduction of the vertebral body height was not significantly different. The measurement of the angles made by the screws on the rods was not significantly different between the cannulated (poly-axial head) and solid (mono-axial head) screw groups. Conclusions: Solid screws were superior in terms of providing increased correction of the kyphotic angle and height of the fractured vertebra than the cannulated screws; however, no difference was noted between the screws in the maintenance of the superior and inferior angles of the screw with the rod.

• Journal of Trauma and Injury
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• v.23 no.2
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• pp.96-101
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• 2010

Purpose: This study was conducted in order to evaluate the epidemiological characteristics of?children with fall-down injuries according to age groups and to analyze the major trauma groups that were treated at the emergency room (ER). Methods: Among 1,222 children under age 6 who were treated at the ER from January 2008 to December 2009, a retrospective study was conducted through examination of medical records. The children were classified by age into 3 groups: infant, toddler, and pre-schooler. In each group, the differences between the causative factors that led to the fall-down injuries were analyzed. Also, ISS (Injury Severity Score) score above 4 was classified as major trauma, and an ISS score 0-1 was classified as a minor trauma. The relationship between major trauma and age group was also analyzed. Results: Through an analysis of child fall-down injuries, men (56.6%), toddler (47.3%), head-related symptoms (72.9%), furniture-related traumas (80.2%), and falls from less than a 1-m height (69.9%) were found to be common factors. Furthermore, in radiological studies, fractures and brain hemorrhages accounted for 16.9% of major traumas, and simple skull fractures were the most common (21.4%). Distributed according to age group, the factors relevant to fall injuries were fall height and head-related symptoms for infants, accident site, fall height and head-related symptoms for toddlers, and accident site for pre-schoolers (p<0.05). Also, headrelated symptoms and fall height were independent factors of major trauma in all age groups. However, major traumas (17.3%) were related to dumped trauma, fall height and accident site (p<0.05). Conclusion: This study was mainly about head-related injuries, and toddler were most common victims. The relevant factors for the major trauma were falling height for infants, accident site and falling height for toddlers, and accident site, falling height for pre-schoolers.

• Journal of radiological science and technology
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• v.46 no.4
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• pp.295-301
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• 2023

In addition to protocol adjustments during CT examinations, the height of the CT table can also affect image quality. Therefore, this study aimed to investigate the change in image quality depending on the height of the table in brain CT, which accounts for a large proportion of CT examinations, by measuring signal to contrast to noise ratio (CNR) and noise power spectrum (NPS) using the head phantom and evaluating them. The head phantom images were acquired using Philips Brilliance iCT 256. When the image was acquired, the table height was adjusted to 815, 865, 915, 965, 1015, and 1030 mm, respectively, and each scan was performed 3 times for each height. The CNR result showed the highest value at 965 mm, which is the height adjacent to the center of the head phantom. NPS showed the lowest NPS at 915 mm, the center of the head phantom in the low frequency region. From these results, it can be seen that the height of the table in CT examination is closely related to the image quality, and it can be seen the characteristics of image quality according to CT table through quantitative evaluation methods such as CNR and NPS.

• The Research Journal of the Costume Culture
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• v.12 no.6 s.53
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• pp.1021-1030
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• 2004

The purpose of this study was to develop and make the head form by setting the region of the head for detailed measurement of the head to make the type of closely fit hat and typifying the head form of Korean women's with each region of the head based on the measurements of each region of the head according characteristics. A total of 285 Korean women's in the age group of 18 to 35 years old. It were measured through the direct measurement method by selecting 67 measurement items. As a result of the findings obtained from cluster analysis could be classified into 3 type. Type 1($46\%$) is U-shaped form, that is high in head height on sides and circumference is smallest, whose facial region and occiput is flattest of three types. Type 2($22.4\%$) is inverted triangle form, that is flat in head ridge, low in head height on sides and wide in the frontal width. Type 3($31.6\%$) is oval form, that is largest in size, has the projected occiput and is of three-dimensional form.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.45-50
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• 1997

In recent years the recording density of hard disk has been increasing largely due to the decreasing flying height of head. However, as the flying height is decreased the reliability issue becomes ever more critical. This is because the reliability and durability of hard disk is related to the head/disk interaction as the two components come into partial or full contact. In this work characteristics of friction and stiction in head/disk interface was investigated using constant speed drag test and CSS(contact-start-stop) test. The purpose of this research is to identify the frictional properties of head/disk interface

• The Journal of Korea CHUNA Manual Medicine
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• v.5 no.1
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• pp.213-222
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• 2004

Objectives : To investigate contributing degree of other factors except pelvic tilting to F.L.L.D by analizing with Gonstead technique on the correlation between femur head height discrepancy on the standing pelvic AP view and F.L.L.D caused by pelvic tilting. Method : We analysed standing pelvis AP X-ray of 70 patients who had visited at the department acupunture and moxibustion in Conmaul oriental medical hospital, during May, 1st, 2004 - July, 30th, 2004, with low back pain or lower extremity pain. We excluded the person with any past history of polio, genetic defect, malunited fracture, growth plate injury, infection and overgrowth attributable to hemangioma, or arteriovenous fistula. Results & Conclusion : The functional leg length discrepancy caused by pelvic tilting and femur head height difference had no statistical difference(p=0.132) but poorly correlated(Pearson ${\nu}=0.05$). In the 94.28% of subjects, the femur head height difference wasn't in accord with F.L.L.D. caused by pelvic tilting. In 47.14% of subjects were expected to have over $3^{mm}$ of leg length discrepancy after pelvic adjustment. The mean of measurement difference between two methods was $3.76{\pm}3.12^{mm}$ and the range was $0{\sim}11.4^{mm}$. Consequently, we must consider not only functional leg length discrepancy caused by pelvic tilting but also anatomical leg length discrepancy, misalignment of ankle, knee or hip joint etc.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.132-139
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• 2005

The driving position of head restraints and the relative risk of neck injury were studied in the computer simulation. MADYMO human model with the detail neck model was used to define the magnitude and direction of internal forces acting on the cervical spine during rear-end impact and to determine the effect of the initial position of the occupant's head with respect to the head restraints. Maximum reaction forces were generated during the head contact to the restraint and relatively large forces were generated at each spinal components in lower cervical spine in proportion to backset and height distance increasement.