• Korean Journal of Applied Biomechanics
• /
• v.14 no.3
• /
• pp.67-82
• /
• 2004

The purpose of this study was to evaluate the function and the safety of an additional weight shoe developed for the improvement of aerobic capacity, and to improve some problems found by subject's test for an additional weight shoe. The subjects employed for this study were 10 college students. 4 video cameras, AMTI force platform and Pedar insole pressure distribution measurement device were used to analyze foot motions. The results of the study were as follows: 1 The initial achilles tendon angle and initial rearfoot pronation angle of an additional weight shoe during walking were 183.7 deg and 2.33 deg, respectively, and smaller than a barefoot condition. Maximum achilles tendon angle and the angular displacement of achilles tendon angle were 185.35 deg and 4.21 deg respectively, and smaller than barefoot condition. Thus rearfoot stability variables were within the permission value for safety. 2. Maximal anterior posterior ground reaction force of additional weight shoe was appeared to be 1.01-1.2 B.W., and was bigger than a barefoot condition. The time to MAPGRF of an additional weight shoe was longer than a barefoot condition. Maximal vertical ground reaction force of additional weight shoe was appeared to be 2.3-2.7 B.W., and was bigger than a barefoot condition in propulsive force region. But A barefoot condition was bigger in braking force region. The time to MVGRF of an additional weight shoe was longer than a barefoot condition. 3. Regional peak pressure was bigger in medial region than in lateral region in contrast to conventional running shoes. The instant of regional peak pressure was M1-M2-M7-M4-M6-M5 -M3, and differed form conventional running shoes. Regional Impulse was shown to be abnormal patterns. There were no evidences that an additional weight shoe would have function and safety problems through the analysis of rearfoot control and ground reaction force during walking. However, There appeared to have small problem in pressure distribution. It was considered that it would be possible to redesign the inner geometry. This study could not find out safety on human body and exercise effects because of short term research period. Therefore long term study on subject's test would be necessary in the future study.

• The korean journal of orthodontics
• /
• v.32 no.6 s.95
• /
• pp.425-434
• /
• 2002

The purpose of this investigation was to study the spatial changes of the maxillofacial complex following maxillary protraction transmitted to the center of resistance of a dry juvenile human skull by a modified maxillary protraction appliance. Four dry juvenile human skulls (without mandible) with well aligned upper deciduous dentition and early mixed dentition were used as experimental samples. A modified protraction headgear was fabricated from a Delare's facemask, and following an alginate impression, an orthodontic resin maxillary splint was made for each dry skull. Protraction force level was maintained at approximately 1000gm per side for 6 hours. Cephalometric radiographs were taken pre- and post- protraction, and nine reference markers with 1.5 mm length of $.017\times.025$ TMA wire were placed on the right side of the skull for an accurate superimposition of serial cephalometric radiographs. The present investigation demonstrated that vertical changes associated with an anterior displacement of the maxillary complex was observed, and the most prominent effect of protraction headgear was a counterclockwise rotation of the maxilla, that is, a forward and downward tipping around the palatomaxillary region.

• Radiation Oncology Journal
• /
• v.36 no.1
• /
• pp.54-62
• /
• 2018

Purpose: To investigate set-up errors, suggest the adequate planning target volume (PTV) margin and image-guided radiotherapy frequency in head and neck (H&N) cancer treated with intensity-modulated radiotherapy (IMRT) assessed by kV cone-beam computed tomography (CBCT). Methods: We analyzed 360 CBCTs in 60 patients with H&N cancer treated with IMRT. The target delineation was contoured according to ICRU62. PTVs were generated by adding a 3-5 mm margin in all directions to the respective clinical target volumes. The kV CBCT images were obtained at first three days of irradiation and weekly thereafter. The overall mean displacement, range, systematic (${\Sigma}$) and random (${\sigma}$) errors were calculated. Adequate PTV margins were calculated according to the van Herk formula ($2.5{\Sigma}+0.7r$). Results: The mean of set-up errors was less than 2 mm in any direction. The overall frequency of set-up displacements greater than 3 mm was 3.9% in medial-lateral (ML) direction, 8% in superior-inferior (SI) direction, and 15.5% in anterior-posterior (AP) direction. The range of translations shifts was 0-9 mm in ML direction, 0-5 mm in SI direction and 0-10 mm in AP direction, respectively. After systematic set-up errors correction, the adequate margin to overcome the problem of set-up errors was found to be less than 3 mm. Conclusion: Image-guided kV CBCT was effective for the evaluation of set-up accuracy in H&N cancer. The kV CBCT at first three fractions and followed-by weekly appears adequate for reducing significantly set-up errors in H&N cancer treated with IMRT technique. Finally, 3-5 mm PTV margins appear adequate and safe to overcome the problem of set-up errors.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.22 no.2
• /
• pp.217-232
• /
• 2000

The author studied on the 128 cases of benign odontogenic tumors which had been diagnosed with biopsy during the period of Jan. 1989 to Dec. 1998 at the Kyungpook National University Hospital, Yeungnam University Medical Center, Keimyung University Dongsan Medical Center, and Taegu Catholic Medical Center. This study contained the clinicostatistical analysis of the frequency in relation to sex, age, locations, chief complaints, duration, radiographic findings, recurrence, teeth, and treatment methods. The results were as follow : 1. Of a total of 128 benign odontogenic tumors, ameloblastomas(57 cases; 44.5%) and odontomas (44 cases ; 34.4%) mostly occupied. The other types of lesions were 8 calcifying odontogenic cysts, 7 benign cementoblastomas, 4 myxomas, 3 adenomatoid odontogenic tumors, 2 calcifying epithelial odontogenic tumors, 2 ameloblastic fibro-odontomas, and 1 odontogenic fibroma. 2. In age and sex distribution, benign odontogenic tumors occured slightly more often in males(53.9%) than females(46.1%) and the majority of cases(79.7%) were found during 2nd, 3rd, and 4th decade. 3. There was a predilection for mandibular lesions(mandible-maxilla ratio, 2.6 : 1). 4. The most common chief complaint was swelling(29.7%) and in respect to duration, the cases less than 1 year(50.0%) mainly appeared. 5. There were 7 cases(13.0%) of recurrence on ameloblastoma and there was no recurrence in the others. 6. In Ameloblastoma It commonly occured during 3rd and 4th decade(59.6%) and mean age was 30.2 years. The majority of cases were occurred in mandible(96.5%) , especially mandibular molar and angle area(71.9%). The most common chief complaint was swelling(47.4%) and in respect to duration, the cases less than 1 year(52.6%) mainly appeared. In relation to teeth, there were resorption of root(52.6%), displacement of teeth(31.6%), and in relation to impacted teeth(43.9%). There was higher recurrence rate in the cases by conservative treatment(14.7%) than radical treatment(10.0%). As regards radiographic findings, conservative treatments were prevalent in the cases of unilocular type(85.7%) as compared with multilocular type(48.5%). and there was higherrecurrence rate in the cases of multilocular type(18.2%) than unilocular type(4.8%). As regards the type of treatment in relation to age, conservative treatments were prevalent in patients younger than 20 years of age. 7. In Odontomas It commonly occured during 2nd decade(50.0%) and in maxillary anterior teeth(40.9%). The most common chief complaint was delayed retention and permanent impaction of teeth(72.7%), and most frequently associated with impacted teeth(79.5%).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.18 no.1
• /
• pp.81-136
• /
• 1988

The aim of this study was to determine whether T.M.J. tomographic examination yielded significant differences in condyle positions among asymptomatic, myalgia, derangement, and arthrosis groups of T.M.J. disorders. The author obtained sagittal linear tomograms of right and left T.M.Js. of 36 asymptomatic, 22 myalgia, 54 derangement, and 31 arthrosis patients taken at serial lateral, central, and medial sections in the intercuspal position after submentovertex radiographs analyzed. With the dual linear measurements of the posterior and anterior interarticular space, condyle positions were mathematically expressed as proportion. All data from these analysis was recorded and processed statistically. The results were obtained as follows. 1. In asymptomatic group, radiographically concentric condyle position was found in 50.0% to 65.4% of subjects, with a substantial range of variability. No significant differences existed between men and women and also between right and left T.M.Js. for condyle position. 2. In women, significant difference for mean condyle position of left lateral section of each diagnostic category existed between derangement and myalgia groups (P<.05). Also that of left central section existed between derangement and myalgia groups, and that of left medial section existed between derangement and myalgia groups (P<.05). 3. In main-symptom side, condyle position in myalgia group was more concentric, and condyle position in derangement group was more posterior. This showed significant differences between derangement and myalgia groups in lateral, central, and medial sections of main- symptom sides, and only between derangement and myalgia groups in central section of contra-lateral sides (P<.05). Condyle position in arthrosis group was broadly distributed among all positions. 4. In contra-lateral side, significant difference for mean condyle position of central section of each symptomatic group existed between derangement and myalgia groups (P<.05). Condyle position in derangement group was more posterior. The distribution of the condyle position of contra-lateral side in patients with unilateral symptoms was similar to that of main-symptom side in each symptomatic group. No significant difference existed between main-symptom and contra-lateral sides. 5. For internal derangement subgroups, condyle position in reducible disc displacement group was more posterior than non-reciprocal and locking groups, but there was no significant difference. 6. From 16 to 25 years, significant difference for mean condyle position of medial section of main-symptom side of each symptomatic group existed between myalgia and derangement groups (P<.05).

• The Journal of Korean Academy of Prosthodontics
• /
• v.28 no.1
• /
• pp.63-94
• /
• 1990

The purpose of this study was to analyze the displacement and the magnitude and the mode of distribution of the stresses in the lower overdenture, the mucous membrane, the abutment tooth and the mandibular supporting bone when various denture base materials, such as acrylic resin and 0.5mm metal base, and various denture base designs were subjected to different loading schemes. For this study, the two-dimensional finite element method was used. Mandibular arch models, with only canine remaining, were fabricated. In the first denture base design, a space, approximately 1mm thick, was prepared between the denture and the dome abutment. In the second denture base design, contact between the denture and the dome abutment was eliminated except the contact of the occlusal third of the abutment. In order to represent the same physiological condition as the fixed areas of the mandible under loading schemes, the eight nodes which lie at the mandibular angle region, the coronoid process and the mandibular condyle were assumed to be fixed. Each model was loaded with a magnitude of 10 kgs on the first molar region(P1) and 7 kgs on the central incisal region (P2) in a vertical direction. Then the force of 10 kgs was applied distributively from the first premolar to the second molar of each model in a vertical direction(P3). The results were as follows. : 1. When the testing vertical loads were given to the selected points of the overdenture, the overdenture showed the rotatory phenomenon, as well as sinking and the displacements of alveolar ridge, abutment and lower border of mandible under the metal base overdenture were less than those under the acrylic resin overdenture. 2. The maximum principal stresses(the maximum tensile stresses) being considered, high tensile stresses occured at the buccal shelf area, the posterior region of the ridge crest and the anterior border region of the mandibular ramus. 3. The minimum principal stresses(the maximum compressive stresses) being considered, high compressive stresses occured at the inferior and posterior border region of the mandible, the mandibular angle and the posterior border region of the mandibular ramus. 4. The vertical load on the central incisal region(P2) produced higher equivalent stress in the mandible than that on any other region(P1, P3) because of the long lever arm distance from the fixed points to the loading point. 5. Higher equivalent stresses were distributed throughout the metal base overdenture than the resin base overdenture under the same loading condition. 6. The case of occlusal third contact of the abutment to the denture produced higher equivalent stresses in the abutment, the mandibular area around the abutment and the overdenture than the case of a 1mm space between the denture and the abutment. 7. Without regard to overdenture base materials and designs, the amounts and distribution patterns of equivalent stresses under the same loading condition were similar in the mucous membrane.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.4
• /
• pp.201-208
• /
• 2007

The purpose of this study is to compare 4 different body punch types(type 1: a punch using a shoulder, type 2: a punch using a waist, type 3: a punch using lower extremities, and type 4: a punch with elbows by your side at chest level) in horseback-riding stance and establish suitable teaching theory and method, which would be a useful reference to Taekwondo instructors on the spot(in Taekwondo dojangs all around Korea). Five exhibition players from Korean national Taekwondo exhibition team participated in this study. Each participant was asked to perform the four different types of punches and their kinematic and kinetic data were recorded with 7 vicon cameras(125Hz) and two force plates(AMTI, 1200Hz). We analyzed displacement, time, resultant center of body mass trajectory, velocity, trunk angular velocity, and ground reaction force(GRF) from each body segment in body punch and the result. I performed 1-way ANOVA(RM) for average values of each player after standardization and statistical significance was set as p<.05. was as the following ; First, they showed a tendency to take the body punch posture with the biggest motion at a shoulder and on descending order a waist and a knee. Second, a mean time for each body punch on ascending order 0.46sec. for type 2, 0.49sec for type 3, 0.50sec. for type 4, and 0.56sec. for type 1. Third, a mean resultant center of body mass trajectory for each body punch the longest 4.07cm for type 3 and the shortest 2.458cm for type 1. Fourth, a mean of maximal velocity of a fist strike was the fastest 5.99m/s for type 3, 5.93m/s for type 4, 5.67m/s for type 2, and 5.01m/s for type 1 on the descending order. Fifth, a mean of maximal trunk angular velocity of the fastest 495.6deg./sec. for type 4 and 337.7deg./sec. for type 1 on the descending order. Sixth, strongest value was type 3, 2 for anterior-posterior ground reaction force(left -54.89N, right 60.58N), type 4 for medial-lateral GRF(left 83.59N, right -80.12N), and type 3 for vertical GRF(left 341.79N, right 426.11N).

• Fire Science and Engineering
• /
• v.27 no.5
• /
• pp.75-79
• /
• 2013

Application of the left lateral tilt position has been recommended during cardiopulmonary resuscitation (CPR) of pregnant patients. However, the left lateral tilt could displace the left ventricle (LV) besides the gravid uterus and may compromise the cardiac pump mechanism of CPR. Thus, we investigated the effect of left lateral tilt on the spatial relationship between the anterior-posterior axis (AP axis), which represents the direction of sternal displacement during CPR, and the LV. We retrospectively reviewed the medical records and multidetector computed tomography (MDCT) scans of 90 patients who underwent virtual gastroscopy using MDCT. Virtual gastroscopy was performed with the patient both in the left lateral tilt position and in the supine position. On an axial image showing the maximal area of the LV, the angle between the AP axis and the LV axis ($Angle_{AP-LV}$), the shortest distance between the AP axis and the mid-point of LV cavity ($D_{AP-MidLV}$) and the shortest distance between the AP axis and the LV apex ($D_{AP-Apex}$) were measured. In the supine scans, the LV was situated on the left side of the AP axis in 87 patients (96.7%). On the left lateral tilt scans, the mean tilt angle was $43.4{\pm}11.0^{\circ}$. $D_{AP-MidLV}$ and $D_{AP-Apex}$ were significantly longer in the left lateral tilt position (p<0.001), but $Angle_{AP-LV}$ was comparable between the positions. This study indicates that the left lateral tilt position may compromise the cardiac pump mechanism of chest compression in pregnant cardiac arrest patients.

• Clinics in Shoulder and Elbow
• /
• v.2 no.2
• /
• pp.178-186
• /
• 1999

Twenty-three patients with chronic shoulder pain beyond 6 months after the fracture of the greater tuberosity underwent arthroscopic treatment and were retrospectively assessed after an average of 29 months(range, 22 to 40 months). There were 18 men and 5 women with the average age of 39 years(range, 24 to 61 years). Fourteen were isolated fractures and nine were related to acute anterior instability episode. The average displacement of the fracture was 2.3mm(range, 0 to 4mm) on the anteroposterior view of the plane radiographs. At the time of arthroscopy, all patients had partial thickness rotator cuff tears in the articular surface. The cuff tears were located on the tuberosity fracture area and were an Ellman's grade I to n in depth. With the arthroscopic debridement or repair of the tear depending on the condition of the tear itself, as well as the subacromial decompression, the UCLA score revealed good to excellent results in 20 and fair in 3 patients. Nineteen of the patients had returned to the previous level of activities. The patient with a higher activity demand revealed a lower level of activity return(p=0.034). The partial thickness rotator cuff tear should be considered in patients with chronic shoulder pain after the minimally displaced fracture of the greater tuberosity, and arthroscopic debridement or repair is an appropriate procedure.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.29 no.3
• /
• pp.249-258
• /
• 2013

The purpose of this study was to investigate how image magnification in dental panoramic radiography is influenced by object position. Five metal balls (4 mm in diameter, 2 for the anterior and 3 for the posterior region on the right side) were placed above alveolar crest of dry skull considering extraction socket and dental arch. Dry skull was radiographed using OP-100D (Instrumentarium Imaging Co., Tuusula, Finland) at proper and displaced position along the sagittal and transverse plane at 3 mm, 6 mm, 9 mm, 12 mm and 15 mm using special mount which can control precise movement. Images were stored in DICOM files and were measured by ruler equipped within INFINITT PACS software (Infinitt Co., Ltd., Seoul, Korea). The mean horizontal magnification was 1.224-1.439 and mean vertical magnification was 1.286 - 1.345 at proper position. Vertical magnification resulted in less variation (1.245-1.418) than horizontal magnification (0.798-6.297) according to the sagittal and transverse displacements. Head positioning is important for linear measurement on panoramic radiography and inclusion of standard object (for instance, metal ball) is helpful to anticipate exact magnification of panoramic radiographs at various location.