• Imaging Science in Dentistry
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• v.38 no.1
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• pp.17-22
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• 2008

Purpose: It is important to determine the bucco-lingual inclination of implants on radiographs before the implant surgery. The purpose of this study was to compare the buccolingual inclination in alveolar bone and the tooth with dental cone beam CT and to prepare the standard for the buccolingual inclination of implant. Materials and Methods: Axial, panoramic, and buccolingually sectioned images of 80 implant cases with stent including straight marker using CB $Mercuray^{TM}$ (Hitachi, Japan) were evaluated. The comparison of the buccolingual inclination of remained alveolar bone with the tooth and the marker on butcolingually sectioned views was performed statistically. Results: The average buccolingual inclination of remained alveolar bone and tooth was $82.8{\pm}4.6^{\circ}\;and\;85.8{\pm}4.7^{\circ}$ (p<0.05, r=0.96) at the 1st molar area and $76.4{\pm}1.7^{\circ}\;and\;82.7{\pm}1.7^{\circ}$ respectively (p>0.05, r=0.12) at the 2nd premolar area in upper jaw. The average buccolingua1 inclination of remained alveolar bone and tooth was $81.3{\pm}8.3^{\circ}\;and\;87.5{\pm}6.3^{\circ}$ (p>0.05, r=0.85) at the lower 2nd premolar area and $94.3{\pm}6.6^{\circ}\;and\;93.3{\pm}7.2^{\circ}$ respectively (p>0.05, r=0.91) at the 1st molar area in lower jaw. The inclinations of markers were very different from those of remained bone at the most of areas except the upper 2nd premolar area (r=0.79). Conclusion: We recommend dental CBCT analysis for determining the buccolingual inclination of dental implant, because of significant difference, in average, between the bucco1ingual inclination of remained alveolar bone and tooth.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.11 no.1
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• pp.65-73
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• 2005

Osteoarthritis has been considered a disease of the elderly because it is uncommon before the age of 40 years and is seen in approximately 80% of United States citizens older than 65 years. general population on kuri city in korea revealed that prevalence of knee osteoarthritis is 10.2%, increasing with age. High level of physical activity in men and age, post-menopause and obesity in women can be risk factor. Osteoarthritis is no evidence that a acquired process initiated much earlier in life through mechanical, metabolic, genetic, or other origins. A high tibial osteotomy alters static lower extremity alignment thereby decreasing medial compartment loading. As well, conservative treatment strategies, such as knee braces and valgus heel wedges, affect lover limb mechanics and attempt to reduce medial compartment loading. It was hypothesized that valgus heel wedges and modified orthoses would shift the center of pressure laterally on the foot during level walking, reducing the moment arm of the adduction moment in the frontal plane, thereby resulting in a decrease in the knee adduction moment. In the 1980s, the effect of wearing a laterally wedged insole on osteoarthritic patients with a varus deformity of the knee was firsted, and since then, kinematic and kinetic analyses concerning this condition have mainly focused on a static standing position. Since the early 1990s, the beneficial effect of wearing a laterally wedged insole to treat osteoarthritis of the knee has also been reported in dynamic conditions, but these studies did not answer the question of the kinematic and kinetic mechanisms that resulted in the reduced symptoms in patents with knee osteoarthritis. therefore, the effect of wearing laterally wedged insole has not been sufficiently studied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.995-1003
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• 2005

Since the sensor network nodes have a small size and limited battery power, there have been many studies for reducing their energy consumption. Each sensor node can show different energy usage according to the frequency of event sensing and data transmission, and thus they have different lifetime. So, some nodes may run out of energy that causes disconnection of paths and reduction of network lifetime. In this paper, we propose a new energy-efficient routing algorithm for sensor networks that selects a least energy-consuming path among the paths formed by node with highest remaining energy and provides long network lifetime and somewhat uniform energy consumption by nodes. Simulation results show that our algorithm extends the network lifetime and enhances the network reliability by maintaining relatively uniform remaining energy distribution among sensor nodes.

• Journal of Technologic Dentistry
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• v.40 no.1
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• pp.41-47
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• 2018

Purpose: The purpose of this study was to analyze the biomechanical properties of the dental implants on the supporting bone using three-dimensional finite element method when three different abutment materials were applied to the implant system. Methods: Three different dental implant models were fabricated by applying Ti, PEEK, and CRE-PEEK (60% carbon-reinforced PEEK) to abutment material. The abutment and connecting screw from the fixture was applied with a tightening torque of 20 Ncm. And then, total loads of 150 N were applied in an $30^{\circ}oblique$ direction (to the vertical). The structural stability of dental implants on the supporting bone was analyzed using Von Mises stress and principal stress values. Results: The maximum tensile stress of the cortical bone was highest at 12.6 MPa in the PEEK abutment (Model-B). Ti abutment (Model-A) and CRE-PEEK abutment (Model-C) showed similar stress distributions (10.6 and 10.3 MPa, respectively). And the maximum compressive principal stress was similar in all models. The Von Mises stress value delivered to the bone around the implant was highest at 16.5 MPa in Model-B. On the other hand, Model-A and C showed similar stress distributions (14.0 and 13.8 MPa, respectively). In addition, the maximum equivalent stress applied to the abutment was highest at 629.8 MPa in Model-A. The stress distribution in Model-C was 573.9 MPa. Whereas, Model-B showed the lowest value at 165.6 MPa. Conclusion : The dental implant supporting bone system using PEEK material seems to have the possibility of supporting bone fracture. It was found that the CRE-PEEK abutment can reduce the elastic deformation and reduce the stress value of the interfacial bone.

• Journal of Technologic Dentistry
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• v.40 no.2
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• pp.63-69
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• 2018

Purpose: The purpose of this study is to investigate the non-precious metal core materials used in the dental laboratory to fabricate the implant superstructure by CAD / CAM method. And to observe and compare the morphology and distribution of the osteoblasts in relation to implant osseointegration. Methods: In this study, the mandibular right first molar tooth model was selected as an international standard to produce a single core. Using this model, the impression was made with the silicone rubber, the tooth model was scanned, and a single core was designed and 5-axis milling was performed. The materials used were Cobalt-Chromium and Nickel-Chromium, and the cores for dental implant top structures were fabricated according to the procedures of the dental labs. After the fabrication, the marginal area of the core was separated and cell culture experiment was performed. The osteoblast cells used MC3T3-E1, which is currently widely used. For morphological analysis of osteoblasts, cells were posttreated and observed using CLSM (Confocal Laser Scanning Microscope) and compared. Results: The cell adhesion behavior of the specimen surface measured by CLSM was uniformly distributed in specimen A (Cobalt-Chromium) than in specimen B (Nickel-Chromium). The distribution and changes of the cells were different in the two specimens. Conclusion : It is possible to confirm that specimen A (Cobalt-Chromium) is suitable for the living body through adhesion and proliferation of osteoblasts related to implant osseointegration in the non-precious metal superstructure used after implantation. It is considered that it is preferable to use Co-Cr when fabricating the superstructure.

• The Korean Journal of Malacology
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• v.31 no.1
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• pp.27-34
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• 2015

The anatomy and ultrastructure of the digestive diverticulum of Tegillarca granosa were described using light and electron microscopy. The digestive diverticulum was situated on the gonad and connected to stomach by a primary duct. Digestive diverticulum is composed of numerous digestive tubules. The epithelial layer of digestive tubule, which is simple, is composed of basophilic cells and digestive cells. Basophilic cells are columnar in shape, and the electron density is higher than that of the digestive cell. The cytoplasm has a well-developed endoplasmic reticulum, tubular mitochondria, Golgi complex and of membrane-bounded granules of high electron density. Digestive cells were classified into three types. According to cell shape, electron density and cell organelles. However, three types of epithelia was same that striated border was observed in free surface and lysosome was observed in cytoplasm. The results of this study suggest that basophilic cells and digestive cells in the digestive tubule are specialized in the extracellular and intracellular digestions, respectively.

• Journal of the Korean institute of surface engineering
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• v.43 no.1
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• pp.25-30
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• 2010

Titanium and titanium alloys are widely used for orthopedic and dental implants for their superior mechanical properties, low modulus, excellent corrosion resistance and good biocompatibility. In this study, corrosion behaviors of nanotube formed on the bone plate of Ti-6Al-4V alloy for dental use have been investigated. $TiO_2$ nanotubes were formed on the dental bone plates by anodization in $H_3PO_4$ containing 0.6 wt % NaF solution at $25^{\circ}C$. Electrochemical experiments were performed using a conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. Anodization was carried out using a scanning potentiostat (EG&G Co, Model 263A USA), and all experiments were conducted at room temperature. The surface morphology was observed using field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy(EDS). The corrosion behavior of the dental bone plates was examined using potentiodynamic test(potential range of -1500~2000 mV) in a 0.9% NaCl solution by potentiostat (EG&G Co, PARSTAT 2273. USA). The inner diameter of nanotube was about 150~180 nm with wall thickness of about 20 nm. The interspace of nanotube to nanotube was 50 nm. The passive region of the nanotube formed bone plates showed the broad range compared to non-nanotube formed bone plates. The corrosion surface of sample was covered with corrosion products.

• The Journal of the Korean bone and joint tumor society
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• v.3 no.2
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• pp.89-97
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• 1997

Twenty hundred and five out of 266 patients who were registered in Korea Cancer Center Hospital from Mar. 1985 to Jan. 1994, were analyzed in the aspect of survival and local recurrence. Fifty one patients were excluded due to inadequate data and follow up. Prognostic factors for survival were evaluated statistically. One hundred and four cases were male, 101 female. Average age was 39.7(range 1 to 77) year with a peak incidence around 4th decade. The most frequent diagnosis was malignant fibrous histiocytoma(MFH)(24.1%). Liposarcoma, synovial sarcoma, rhabdomyosarcoma, malignant peripheral nerve sheath tumor and fibrosarcoma were relatively common diagnostic entities, in decreasing order. In location, extremity was 179(87.3%) and trunk 26(12.7%). Average follow up period was 7.5 years(6 months to 10 years). Actuarial 5 years and 10 years survival rate were 64.0% and 40.8% respectively. In univariate analysis with log-lank test, significant differences in survival rate were noted in histopathological diagnosis, size(10 cm), stage and metastasis. Age, sex, tumor location, tumor depth and local recurrence didn't affect the survival rate. Adjuvant chemotherapy and/or radiotherapy did not affect overall survival rate, but lowered the local recurrence rate when compared with surgery only. Surgical margin did not affect the survival rate, but local recurrence rate was different according to each margin; 5.7% in more than wide; 39.5% in marginal; and 60.0% in intralesional excision. In multivariate analysis for results of univariate analysis with Cox's propotional model, metastasis was a meaningful factor for survival of soft tissue sarcoma.

• The Journal of the Korean bone and joint tumor society
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• v.3 no.2
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• pp.112-118
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• 1997

Multicentric chondrosarcoma other than the mesenchymal subtype is rare separate entity. We experienced a case with nonmonomelic synchronous multicentric chondrosarcoma without any preexisting lesions of Oilier's disease or Maffucci's syndrome. To our knowledge, there was no report of synchronous nonmonomelic multicentric chondrosarcoma. A thirty-three year old man had right distal thigh pain of one and half year. Bone scan showed hot lesions on medial condyle of right femur and shaft of left femur. Plain X-ray showed osteolytic lesion on right femur and slight cortical thickening and calcific lesion was observed on left femoral shaft. Curettage and bone cement filling was done on both lesions. The pathology reports were grade I chondrosarcoma on both side of femur. At one month from operation, pathologic fracture of left femur occurred on bone cement-host bone junction. Conservative treatment and radiotherapy of 60Gy was done. At 8 months from operation, nonunion was evident. Segmental resection of left femur with contralateral fibula graft and second look operation on right condyle lesion were done. At 6 months from revision, fracture occurred at host-graft bone junction. We removed previous hardware and applied long DCP and massive autogenous bone graft. Afterwards, the patient looks good and union was progressing. But at 4 years from last operation, hypertrophic nonunion occurred. Another revision was done with condylar plate and bone graft and now he is well without any sign of local recurrence or metastasis.

• The Journal of the Korean bone and joint tumor society
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• v.13 no.2
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• pp.146-151
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• 2007

Hemangiopericytoma is a rare malignant vascular tumor that usually occurs in adults. The occurrence of these tumors in infants, known as congenital or infantile hemangiopericytoma, is even rare and their behavior may be more benign than the adult type. Despite of the generally good prognosis associated with this neoplasm, a complete surgical excision has so far been recommended to avoid recurrence, because no definite criteria for determining whether or not the tumor will regress spontaneously have been established to date. We describe a 1-day-old male neonate with congenital hemangiopericytoma, presenting with a left forearm mass at birth. Wide resection was performed at 65 days of age and hemangiopericytoma was diagnosed by histology. There was no tumor recurrence during 32 months of follow-up.