• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.171-178
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• 1998

Silicon piezoresistive absolute pressure sensor for gas leakage alarm system was developed. This sensor must operate normally in the range of $0{\sim}600\;mmH_{2}O$ pressure, and $0{\sim}100^{\circ}C$ temperature. To make the most of this sensor for gas leakage alarm system, gas must not leak from the sensor itself when the diaphragm of the sensor fractures. Thus, the sealed diaphragm cavity was anodically bonded to pyrex 7740 glass under the condition of $10^{-4}$ torr, at $400^{\circ}C$. The sensitivity of developed sensor was $4.06{\mu}V/VmmH_{2}O$ for $600\;mmH_{2}O$ full-scale pressure range. And temperature compensation method of this sensor is to change bridge-in put-voltage linearly in proportion to the temperature variation by using diode(PXIN4001) or Al thin film resistor. By these methods the temperature effect in the range of $0{\sim}100^{\circ}C$ was compensated over 80 % for offset drift, 95 % for sensitivity.

• Korean Journal of Head & Neck Oncology
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• v.19 no.2
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• pp.164-169
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• 2003

Background and Objectives: The reconstruction is very important in Head and neck cancer surgery to repair the defect created by resection of tumors, to enable successful wound healing, to restore function and to provide acceptable cosmesis. The radial forearm free flap has been the most useful reconstructive flap because it provides a moderate amount of thin, pliable, relatively hairless skin and comparatively simple to do with minimal morbidity. The aims of this study is to estimate the outcome of the reconstruction with radial forearm free flap with the several factors in 140 head and neck cancer cases in our hospital for last 10 years. Materials and Methods: Retrospective review of the records of 140 patients underwent resection of the head and neck tumors and reconstruction with a radial forearm free flap from 1993 to 2003. The age, sex of the patients, Primary site, the complication of donor and recipient site, flap survival rate, median time to start diet, patient subjective symtoms about swallowing and articulating and the fact of revision reconstructive surgery were analyzed. Results: In primary pathologic site, 56 cases were oral cavity cancers, 44 cases, oropharyngeal cancers and 22 cases, hypopharyngeal cancers. Flap survival rate was 93.6% (13 leases). On donor site, wound dehiscence, hematoma, sensory change and infection were noted and on recipient site, most common complication were fistula and wound dehiscence. The complication rate of recipient's site was 19.1 % and donor site, 3.5%. In 118 cases (84.3%), the patients could take all kinds of food. Swallowing difficulty were noted in 22 cases 05.7%). In 5 cases, there was articulation difficulty but most of patients except patients having total laryngectomy (18 cases) couldn't have any difficulty in articulation and speaking. Conclusion: We conclude that the radial forearm free flap is the most appropriate reconstructive material for treating the defect in head and neck reconstruction.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.11-22
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• 2003

This study compared the dentin adhesion to composite resin according to air-dry, blot dry, application of rewetting agent on air-dry or blot dry dentin surface by microleakag test and SEM observation. For microleakage test, class V cavity preparations with dentinal margins were prepared on both buccal and lingual surfaces of 40 extracted human molars. For SEM observation, occlusal dentin of 20 extracted human molars were exposed. After etched the dentin, prepared teeth were randomly divided into four groups; D group: air dry for 10-15 sec., B group: blot dry with moist cotton pellet, D-R group: air dry and rewet with Aqua-Prep F for 20 sec., B-R group: blot dry and rewet with Aqua-Prep F for 20 sec. Treated cavities and surfaces were filled or constructed using One-Step adhesives and Aelitefil composite resins. Specimens were stored in distilled water for 24 hours. For microleakage test, the specimens were thermocycled and soaked into 2% methylene blue. The specimens were sectioned longitudinally and evaluated for microleakage under steromicroscope. The data were statistically analysed by Kuskal-Wallis Test, Mann-Whitney and Wilcoxon signed ranked tests. For SEM observation, the specimens were bisectioned mesiodiatally. After decalcified and deproteinized, specimens were observed under SEM. The results of this study were as follows; 1. The microleakges on dentinal margin were the highest in D group compared with B group, D-R group, and B-R group(p<0.05). But there was no significant difference between B group, D-R group and B-R group. 2. D group showed gap and a few resin tags between dentin and composite resin. 3 B group, D-R group, and B-R groups showed close adaptation between dentin and composite resin. It showed that resin rags in B group were numerous and long, in D-R group were few and short, in B-R group were numerous and short or long. 4. Adhesive layer showed in D-R group ($10{\;}\mu\textrm{m}$) and B-R group ($3{\;}\mu\textrm{m}$) In conclusion, use of rewetting agent to dry dentin was efficient to dentin adhesion, also it did not provide reverse effect on blot dry dentin.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.23-33
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• 2003

The purpose of this study was to compare in vitro interfacial relationship of restorations bonded with three self-etching primer adhesives and one self-etching adhesive. Class I cavity preparations were prepared on twenty extracted human molars. Prepared teeth were divided into four groups and restored with four adhesives and composites Clearfil SE $Bond/Clearfil^{TM}$ AP-X (SE), UniFil $Bond/UniFil^{\circledR}$ F (UF), FL $Bond/Filtek^{TM}$ Z 250 (FL) and Prompt $L-Pop/Filtek^{TM}$ Z 250 (LP) After storing in distilled water of room temperature for 24 hours, the specimens were vertically sectioned and decalcified. Morphological patterns between the enamel/dentin and adhesives were observed under SEM. The results of this study were as follows : 1. They showed close adaptation between enamel and SE, UF and FL except for LP. 2. The hybrid layer in dentin was $2{\;}\mu\textrm{m}$ thick in SE, $1.5{\;}\mu\textrm{m}$ thick in UF, and $0.4{\;}\mu\textrm{m}$ in both FL and LP. So, the hybrid layers of SE and UF were slightly thicker than that of FL and LP. 3. The lengths and diameters of resin tags in UF and FL were similar, but those of LP were slightly shorter and slenderer than those of SE. 4. The resin tags were long rod shape in SE, and funnel shape in other groups Within the limitations of this study, it was concluded that self-etching primer adhesives showed close adaptation on enamel. In addition, the thickness of hybrid layer ranged from $0.4-1.5{\;}\mu\textrm{m}$ between adhesives and dentin. The resin tags were long rod or funnel shape, and dimension of them was similar or different among adhesives.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.701-709
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• 1998

Many dental composites are Bis-GMA based resin which diluted with the more fluid monomer triethylenglycol dimethacrylate(TEGDMA). TEGDMA is often present in exess so that some quantity remains unreacted following photo-initiated polymerization. TEGDMA is a component of some resin composites which contributes to their cytotoxicity. The presence of dentin between resin composite and pulp space reduce the cytotoxicity in vitro. The root system from extrcted human third molar was removed and then a circular occlusal cavity 4mm in diameter was prepared, leaving a remaining dentinal thickness to the roof of the pulpal chamber within the range 1.0-1.5mm. Dentine was treated with 37% phosphoric acid prior to Z 100 placement without using bonding resin(group 1). In group 2, SMP(Scotchbond Multi Purpose) primer, bonding resin prior to Z 100 placement were applied sequently. In group 3, moulds with internal dimensions 4mm diameter by 2mm depth were used to contain the composite alone with an equvalent mass on tooth model, and then they were immersed directly into water. The purpose of this study is to evaluate the release rate and quantity of TEGDMA with or without the application of bonding resin. Both release rate and total cumulative amount of TEGDMA for the three groups were determined using reversed-phase HPLC at times up to 10 days. The results were as follows: 1. All experimental groups showed the highest rate of release was in the first sample period(0-4.32 min) and the rate of release declined exponentially thereafter. 2. The maximum release rate and total cumulative account of TEGDMA in the tooth model of group 1 and group 2 with the use of SMP bonding resin were reduced however ther were no significant differences between these groups(P>0.05). 3. In the first sample period(0-4.32 min), the rate of release of TEGDMA from composite resin in group 3 immersed directly into water was significantly higher than that in group 1 and group 2 of tooth model(P<0.05). Conclusively, TEGDMA diffusion from Z 100 resin was not effectively prevented by the presence of dentin in spite of using the SMP bonding resin.

• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.8-19
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• 2009

The purpose of this study was to investigate the effects of four restorative materials under various occlusal loading conditions on the stress distribution at the CEJ of buccal. palatal surface and central groove of occlusal surface of endodontically treated maxillary second premolar, using a 3D finte element analysis. A 3D finite element model of human maxillary second premolar was endodontically treated. After endodontic treatment, access cavity was filled with Amalgam, resin, ceramic or gold of different mechanical properties. A static 500N forces were applied at the buccal (Load-1) and palatal cusp (Load-2) and a static 170N forces were applied at the mesial marginal ridge and palatal cusp simultaneously as centric occlusion (Load-3). Under 3-type Loading condition, the value of tensile stress was analyzed after 4-type restoration at the CEJ of buccal and palatal surface and central groove of occlusal surface Excessive high tensile stresses were observed along the palatal CEJ in Load-1 case and buccal CEJ in Load-2 in all of the restorations. There was no difference in magnitude of stress in relation to the type of restorations. Heavy tensile stress concentrations were observed around the loading point and along the central groove of occlusal surface in all of the restorations. There was slight difference in magnitude of stress between different types of restorations. High tensile stress concentrations around the loading points were observed and there was no difference in magnitude of stress between different types of restorations in Load-3.

• Proceedings of the KACD Conference
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• 2008.05a
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• pp.184-197
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• 2008

This study was to investigate the influence of combining composite resins with different elastic modulus, and occlusal loading condition on the stress distribution of restored notch-shaped non-carious cervical lesion using 3D finite element (FE) analysis. The extracted maxillary second premolar was scanned serially with Micro-CT. The 3D images were processed by 3D-DOCTOR. ANSYS was used to mesh and analyze 3D FE model. A notch-shaped cavity was modeled and filled with hybrid, flowable resin or a combination of both. After restoration, a static load of 500N was applied in a point-load condition at buccal cusp and palatal cusp. The stress data were analyzed using analysis of principal stress. Results showed that combining method such that apex was restored by material with high elastic modulus and the occlusal and cervical cavosurface margin by small amount of material with low elastic modulus was the most profitable method in the view of tensile stress that was considered as the dominant factor jeopardizing the restoration durability and promoting the lesion progression.

• Economic and Environmental Geology
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• v.46 no.2
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• pp.153-163
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• 2013

The Ogcheon Au-Ag deposit consists of two quartz veins that fill the NE or NW-trending fissures in the metasedimentary rocks of unknown age. The quartz veins occur mainly in the massive type with partially breccia and cavity. They can be found along the strike for about minimum 50 m and varied in thickness from 0.1 to 0.3 m. The mineralogy of quartz veins from the Ogcheon deposit is mainly composed of hydrothermal alteration minerals such as pyrite, quartz, sericite, chlorite, clay minerals and sulfides including pyrite, pyrrhotite, arsenopyrite, sphalerite, chalcopyrite and galena. Fluid inclusion data from quartz indicate that homogenization temperatures and salinity of mineralization range from 184 to $362^{\circ}C$ and from 0.0 to 6.6 wt.% eq. NaCl, respectively. These suggest that ore forming fluids were progressively cooled and diluted from mixing with meteoric water. Sulfur(${\delta}^{34}S$: 0.4~8.4‰) isotope composition indicates that ore sulfur was derived from mainly magmatic source although there is a partial derivation from the host rocks. The calculated oxygen(${\delta}^{18}O$: 4.9~12.1‰) and hydrogen(${\delta}D$: -92~-74‰) isotope compositions suggest that magmatic and meteoric ore fluids were equally important for the formation of the Ogcheon deposit and then overlapped to some degree with another type of meteoric water during mineralization.

• Applied Microscopy
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• v.32 no.3
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• pp.213-222
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• 2002

Histology and ultrastructure of the mantle epidermis in the ark shell, Scapharca broughtonii are described using light and electron microscopy. The mantle of the ark shell is composed of outer epidermis, connective tissue and inner epidermis. Both epidermis are simple and consists of supporting cells, ciliated cells and secretory cells. Connective tissue is composed of mainly collagen and muscle fibers. The supporting cells in the inner epidermis are usually columnar and covered with microvilli. The ciliated cell have cilia and microvilli on the free surface, and numerous tubular mitochondria are observed in the apical cytoplasm. Secretory cells are mainly observed in the outer epidermis, and it can be divided into four types of A, B, C and D with morphological features of the secretory granules. Type A cells of mucous cell are found in the marginal and central mantle. And these cells contains numerous secretory granules of non-bounded and low electron density. Type B cells contains numerous rough endoplasmic reticula, well-developed Golgi complex and secretory granules of membrane-bounded and high electron density. Secretory granules of type C cells are divided into fibrous core layer and homogeneous peripheral layer. Type D cells are found in the outer epidermis of the central and umbonal mantle. And secretory granules of these cells are divided into homogeneous core layer and granular peripheral layer. This results suggest that the outer and inner epidermis of the mantle are related with shell formation and cleaning of the mantle cavity, respectively.

• Applied Microscopy
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• v.32 no.3
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• pp.231-246
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• 2002

This study was carried out to investigate the effect of squalene (SQ) on the mouse hepatotoxicity induced by cadmium. ICR male mouse weighting about 30 gm were injected $CdCl_2$ (5.0 mg/kg) and SQ (180 mg/kg) into intraperitoneal. At the 1, 2, 3, 4, 5, 6, 7 days, livers were treated with superoxide dismutase (SOD) activity and transmission electron microscopical method and then observed with electron microscope. The results obtained were summarized as follows: SOD activity in the liver, Group A was higher than in normal. Group B was lower than in Group A. In the histological observation, nucleus of Group A showed irregular shape. Inner cavity of mitochondria swellen and development of cristae weakened. Swelling of Lamellae of rough endoplasmic reticulum (RER) showed. Nucleus of group B showed normal shape. Typical lamellae of RER were observed. These results described above treatment of SQ decreased the hepatotoxicity of the $CdCl_2$ and SOD activity in the mouse liver, and then it suggests SQ may be effective for the recovery of hepatic cell.