• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.23-32
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• 2002

The torsional forward extrusion is the process that is executed by punch travel and die rotation. The advantages of having the die rotation on this process are that forming load can be reduced and optimal die angle can be increased. This provides a possibility to extrude cold-worded material where a large extrusion force and die angle are required. Also, this process can improve the material properties owing to the high deformation and uniform strain distribution. The forming load and optimal die angle of this process are determined by the upper bound analysis using stream function and the optimization technique. To verify the theoretical result, we have carried out experiments and FE simulations using DEFORM3D.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.2
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• pp.117-124
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• 2009

Purpose：The purpose of this study was to investigate of the change of the forward head posture(FHP) according to computer using time. Methods：Subjects were 30 male and 30 female. The factors of FHP were measured cranial vertical angle, cranial rotation angle, and head, upper back, neck flexion/extension angle according to computer using time. Change of FHP used to Digital Inclinometry(JTech, Dualer IQTM Dual Inclinometer). The data were collected by data logger(Logger Teknologi HB, Akarp, Sweden). Results：Cranial vertical angle, cranial rotation angle, and head, upper back, neck flexion/extension were increased according to computer using time(p<.05). But cranial vertical angle and cranial rotation angle, and head, upper back, neck flexion/extension were not significant differences between male and female group(p>.05). Conclusion：The effects of cranial vertical angle, cranial rotation angl and head, neck and upper back angle depend on the computer task time. Increased of FHP may result increased tension in posture muscles of cervical spine, resulting in a risk of musculoskeletal disorders.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.4
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• pp.425-432
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• 2014

PURPOSE: The purpose of this study was to investigate that the differences in sternocleidomastoid muscle activity, neck rotation angle, neck lateral bending angle and neck lateral bending onset time between conditions with and without visual biofeedback during neck rotation. METHODS: Ten male and four female adults with condition of forward head posture were recruited in this study. Subjects conducted to left and right maximal neck rotation under the conditions with and without visual biofeedback. During neck rotation, kinematic data of neck rotation, neck lateral bending movement, and electromyography activities of bilateral sternocleidomastold muscles were collected. Differences in dependent variables between conditions with and without visual biofeedback were analyzed using paired t-test. RESULTS: There were significant decreases in lateral bending angle, while lateral bending movement onset time was delayed significantly when applying visual biofeedback (p<.05). However, there were no significant differences in the activation of left and right sternocleidomastoid muscles and neck rotation angle between conditions with and without visual biofeedback (p>.05). CONCLUSION: These findings suggest that visual biofeedback may be effective for axial rotation of cervical spine during neck rotation in adults with forward head posture.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.293-301
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• 2010

The purpose of this study was to investigate the kinematic difference between skilled and less skilled group for the forward walk at dance sports rumba. Six female players(skilled group: 3, less skilled group: 3) were participated as the subjects. To obtain the three-dimensional location coordinates in the joints and segments, it shot with 100Hz/s using 8 video cameras. Step length, shoulder rotation angle, orientation angle and angular velocity of pelvis were analyzed for each trail. The skilled group showed a bigger movement than the less skilled group at the shoulder rotation angle and ROM. The skilled group showed a bigger movement than the less skilled group at the up/down obliquity and internal/external rotation movement for pelvis. And the skilled group showed a bigger movement than the less skilled group at Maximum angle (down obliquity) of P2 and Maximum angle (up obliquity) of P3 to pelvis ROM. The skilled group showed a faster angular velocity than the less skilled group at P2 (+ direction, posterior) of anterior & posterior tilt, P2 & P3 (- direction, up) of up & down obliquity, and P2 (+ direction, external) of internal & external rotation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.163-167
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• 1990

The author has evaluated the panoramic image of the mandibular condyle according to its horizontal condylar angle (0˚, 10˚, 20°, 30°, 40°) and mandibular position (standard, 25㎜ forward and reverse position). The results were as follows: 1. The larger the horizontal condylar angle was, the larger the horizontal magnification was in all positions. 2. In case of small horizontal condylar angle, profile view could be obtained in 25㎜ forward and reverse position. 3. In case of large horizontal condylar angle, profile view could not be obtained in any positions.

• The Journal of the Acoustical Society of Korea
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• v.25 no.3E
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• pp.115-122
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• 2006

The bistatic scattering of an incident wave by a hemi-spherically capped cylinder is of particular interest because it has rarely been studied until the present day. The configuration of a hemi-spherically capped cylinder is similar to naval underwater weapons (submarines, mines, torpedos, etc.), but which is not exactly the same. This paper describes a novel laboratory experiment aimed at direct measurement of bistatic scattering by a hemi-spherically capped cylinder. Bistatic scattering by a hemi-spherically capped cylinder was measured in an acoustic water tank (5m long, 5m wide, 5m deep) using a high frequency projector (120kHz) and hydrophone. Measurements of monostatic scattering were also made under the same conditions. The bistatic scattering pattern by a hemi-spherically capped cylinder was measured against the incident angles $(0^{\circ},\;15^{\circ},\;20^{\circ},\;30^{\circ},\;45^{\circ},\;60^{\circ},\;90^{\circ})$ in order to verify various scattering pattern characteristics by the change of incident angle. The results indicate that the bistatic scattering TS at a wide scattering angle is much stronger than the mono static scattering TS. In bistatic scattering, the forward scattering TS is significantly stronger than the backward scattering TS, and the forward scattering pattern is also broader. In case of seven incident angles, the maximum value of forward scattering TS is about 14dB stronger than that of backward scattering TS. It is also found that forward scattering varies with the incident angle of sound to a much less extent than backscattering, and it is not seriously affected by the incident angle. These features could be the advantages of using forward scattering for detecting underwater targets at long range and increasing detection area and probability.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.23 no.1
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• pp.63-72
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• 2017

Background: The purpose of this case study was to investigate into the effect of complex exercise program on the postural change, gait and balance ability in elementary school students with forward head posture. Methods: Four patients with forward head posture were recruited. They were evaluated pre-treatment, and after 6weeks, using neck disability index (NDI), numeric pain rating scale (NPRS), balance ability, foot pressure (fore foot/rear foot peak pressure ratio, F/R ratio), gait ability (cadence, toe out angle, stance phase). Results: First, the angle of forward head posture (craniovertebral angle; CVA and cranialrotation angle; CRA) was decreased in all subjects. The NPRS and NDI were decreased in all subjects. Also, The cadence, toe out angle and F/R ratio were increased in all subjects. The stance phase of gait cycle was positively change in all subjects. Lastly, the static balance ability improved in all subjects. Conclusion: According to the results above, the complex exercise program for students with forward head posture can help improve the postural change, gait and balance ability. Also, the complex exercise program was able to select interventions depending on the patient's condition and the desired goal.

• The Journal of Korean Physical Therapy
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• v.30 no.4
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• pp.108-111
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• 2018

Purpose: This study examined the effects of the forward head posture and tension type headache on neck movement among office workers. Methods: The subjects were 6 male and 21 female patients composed of a forward head posture group, forward head posture group with a tension type headache and a normal group. Each group consisted of 2 males and 7 females. The cranio-vertebral angle of the head and the angle of motion of the neck were measured. SPSS 23.0 was used for data analysis and one-way ANOVA was performed for the mean comparison of the neck movements in the three groups. Results: The participants had a limitation in the movement of all necks between the forward head posture group and forward head posture with tension type headache group compared to the normal subjects. The forward head posture with tension headache group had limited neck extension and lateral bending compared to the forward head posture group. Conclusion: Office workers have limitations in the movement of the neck when they are accompanied by forward head posture and tension headache. In particular, when accompanied with a tension headache, there is a restriction on the neck extension and side bending. This study is expected to provide basic data for the relief of tension headache and the treatment of forward head posture in office workers.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.178-187
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• 1999

The Cross rolling between flat jaws, as a kind of hot forging, is the forming method to make the axisymmetric multi-step shaft by its rotation and pressure between flat jaws which move in opposite direction. The purpose of this study is to propose the optimal geometric data for shape development of the forward forming region. All data described on this paper are quantified by experiment from initial shape design to final shape development. As the result, proper geometric data are proved that lenth of the first forming area in the forward forming region is 1.5 times larger than circumference of work-piece and the progress angle changes 3 times smoothly.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.2
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• pp.1508-1512
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• 2018

This study was conducted to examine the effect of joint mobilization on forward head posture and to propose an effective method to improve correct body posture and balance. A total of eight patients from a Maitland-applied group (n=8) received mobilization therapy to increase the mobility of the cervical joint, with Maitland's movement grade III intensity for 30 seconds of treatment and 30 seconds of rest, for ten intervals, three times a week for four weeks. The craniovertebral angle (CVA) changes before and after the intervention with the Maitland technique were measured as $56.85{\pm}2.31^{\circ}$ before, $63.23{\pm}2.23^{\circ}$ two weeks after, and $64.98{\pm}1.27^{\circ}$ four weeks after joint intervention. There were significant CVA changes before and after the Maitland technique (P <.05). The results of this study suggest that the Maitland technique is useful for improving the head vertebral angle in patients with forward head posture.