• Journal of Environmental Health Sciences
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• v.44 no.1
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• pp.24-30
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• 2018

Objectives: Based on the amount of amalgam, the duration of exposure, and the water pH, this study aims to investigate the change patterns in the mercury concentrations in water after amalgams have been introduced into sewage water. It is expected that the study results will be useful in improving the system for regulating the amount of mercury that is introduced into the environment. Methods: During the study, a glass test-tube with a cap was washed and disinfected using the glass laboratory device washing method. Then, 1, 2, 3, and 4 tabs were placed into a 10 mL pH 4 solution and 10 mL pH 7 distilled water. Each specimen was prepared in duplicate. The mean of the two mercury concentrations was used as the representative value, and the mercury concentration was measured using a mercury measurement device (DMA-80, Milestone, Italy) a total of eight times at one-week intervals. Results: The results show that the lower was the pH, the higher was the amount of amalgam. Also the longer was the duration, the more significant was the increase of mercury concentration in the water. Conclusions: Dental clinics are collected separately from dental clinics that used them. Given this, dental clinics in Korea must have the necessary facilities to separately collect mercury at their level. In addition, proper disposal systems and social attention to the proper management of dental wastes are required to prevent environmental pollution from mercury.

• Steel and Composite Structures
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• v.29 no.4
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• pp.451-464
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• 2018

This paper presents some quasi-static tests for 4 mixed columns composed of CFST column and RC column. The seismic performance and failure mode were studied under low-cyclic revised loading. The failure mode was observed under different axial compression ratios. The hysteretic curve and skeleton curve were obtained. The effects of axial compression ratio on yield mechanism, displacement ductility, energy dissipation, stiffness and strength attenuation were analyzed. The results indicate that the failure behavior of CFST-RC mixed column with archaized style is mainly caused by bending failure and accompanied by some shear failure. The axial compression ratio performs a control function on the yielding order of the upper and lower columns. The yielding mechanism has a great influence on the ductility and energy dissipation capacity of specimens. Based on the experiment, finite element analysis was made to further research the seismic performance by ABAQUS software. The variable parameters were stiffness ratio of upper and lower columns, axial compression ratio, yielding strength of steel tube, concrete strength and rebar ratio. The simulation results show that with the increase of stiffness ratio of the upper and lower columns, the bearing capacity and ductility of specimens can correspondingly increase. As the axial compression ratio increases, the ductility of the specimen decreases gradually. The other three parameters both have positive effect on the bearing capacity but have negative effect on the ductility. The results can provide reference for the design and engineering application of mixed column consisted of CFST-RC in Chinese archaized buildings.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.169-179
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• 2007

This study was to compare the microshear bond strength $({\mu}SBS)$ of light- and chemically cured composites to enamel coupled with four 2-step self-etch adhesives and also to evaluate the incompatibility between 2-step self-etch adhesives and chemically cured composite resin. Crown segments of extracted human molars were cut mesiodistally, and a 1 mm thickness of specimen was made. They were assigned to four groups by adhesives used: SE group (Clearfil SE Bond) AdheSE group (AdheSE), Tyrian group (Tyrian SPE/One-Step Plus), and Contax group (Contax) Each adhesive was applied to a cut enamel surface as per the manufacturer's instruction. Light-cured (Filtek Z250) or chemically cured composite (Luxacore Smartmix Dual) was bonded to the enamel of each specimen using a Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to ${\mu}SBS$ testing with a crosshead speed of 1 mm/minute. The mean ${\mu}SBS$ (n=20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at 95% level. Also the interface of enamel and composite was evaluated under FE-SEM. The results of this study were as follows ; 1. The ${\mu}SBS$ of the SE Bond group to the enamel was significantly higher than that of the AdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin (p < 0.05). 2. There was not a significant difference among the hdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin. 3. The ${\mu}SBS$ of the light-cured composite resin was significantly higher than that of the chemically cured composite resin when same adhesive was applied to the enamel (p < 0.05). 4. The interface of enamel and all 2-step self-etch adhesives showed close adaptation, and so the incompatibility of the chemically cured composite resin did not show.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.1-8
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• 2007

This study compared the microshear bond strength (${\mu}SBS$) of light-cured and dual-cured composites to enamel bonded with three self-etching adhesives. Crown segments of extracted human molars were cut mesiodistally, and 1 mm thickness of specimen was made. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Adper group (Adper Prompt L-Pop), and AQ group (AQ Bond). Each adhesive was applied to cut enamel surface as per manufacturer's instruction. Light-cured (Filtek Z 250) or dual-cured composite (Luxacore) was bonded to enamel of each specimen using Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to ${\mu}SBS$ testing with a crosshead speed of 1 mm/minute. The mean ${\mu}SBS$ (n = 20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at the 0.05 probability level, The results of this study were as follows ; 1. The ${\mu}SBS$ of light-cured composite was significantly higher than that of dual-cured composite when same adhesive was applied to enamel. 2. For Z 250, the ${\mu}SBS$ of AQ group ($9.95{\pm}2.51 MPa$) to enamel was significantly higher than that of Adper soup ($6.74{\pm}1.80 MPa$), but not significantly different with Xeno group ($7.73{\pm}2.01 MPa$). 3. For Luxacore, the ${\mu}SBS$ of Xeno group ($5.19{\pm}1.32\;MPa$) to enamel was significantly higher than that of Adper group ($3.41{\pm}1.19\;MPa$), but not significantly different with AQ group ($4.50{\pm}0.96\;MPa$).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.73-85
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• 2014

The CFT (Concrete Filled steel Tubes) column-footing connection is cast-in-place embedded type which provides simple construction procedure, low cost, and superior structural performance. In this study, CFT column-footing connection of modular pier is proposed and structural performance is evaluated by experimental tests. To evaluate structural performance of the CFT column-footing connection, a series of experimental tests were performed for the 4 specimens with different embedded depth. As a result of the quasi-static test, the specimen with 0.6D (0.6 times the outside diameter of steel tube) embedded depth showed relatively low ductility than other specimens with larger embedded depth due to cone failure of base concrete occurred during the lower loading step. On the contrary, cone failure of the base concrete was not observed in the specimens with larger embedded depth than 0.9D, but typical flexural failure in lower part of CFT column was observed. With the analyses of force-displacement curve, displacement ductility, and energy dissipation capacity, it is concluded that the rational range of embedded depth of the CFT column-footing connection is from 0.9D to 1.2D in view of good seismic performance.

• Journal of Sensor Science and Technology
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• v.9 no.2
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• pp.96-105
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• 2000

Fiber optic TR-EFPI(total reflected extrtinsic Fabry-Perot interferometric) sensor was developed to measure the strain of structures, such as building, bridge, aircraft, etc. It has been difficult to distinguish the increase and decrease of the strain from the conventional fiber optic EFPI sensor because their signals only have a sinusoidal wave pattern related to the change of strain. Also, the absolute strain could not be measured by the simple fiber optic EFPI sensor. In this study, in order to measure the magnitude of strain with the direction of strain, the fiber optic sensor was simply constructed with the total reflected EFPI sensor probe. This probe was manufactured with a single mode fiber and a mirror coated fiber in a silica glass capillary tube. The output signal of this fiber optic TR-EFPT sensor can give the information about the magnitude and the direction of strain. The loading-unloading test was performed by the universal testing machine with alluminum beam specimen to compare the strain from fiber optic TR-EFPI sensor with the value from electrical strain gauge. In the result of this experiment. the strain from fiber optic TR-EFPI sensor had a good agreement with the values from the electrical strain gauge.

• Journal of Chest Surgery
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• v.32 no.2
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• pp.164-170
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• 1999

Background: The diffuse infiltrative lung disease often requires biopsy for its final diagnosis. Unlike the limited exposure that can be achieved through small thoracotomy incisions in open lung biopsy technique, the thoracoscopic approach allows visualization and biopsy of nearly entire surface of the lung without morbidity of large standard thoracotomy. The purpose of this study was to compare the diagnostic efficacy and operative safety of thoracoscopic lung biopsy(TLB) with open lung biopsy(OLB) in the diagnosis of diffuse infiltrative lung disease. Material and Method: From March 1993 to August 1997, 81 patients were referred for diagnostic lung biopsy. 51 of them underwent standard open lung biopsy and the remaining 30 patients underwent thoracoscopic lung biopsy. Result: Mean operative time was 63 minutes for TLB and 79 minutes for OLB (p=0.04). The volume of biopsy specimen was not different between two groups(TLB 7.8 cm3, OLB 6.9 cm3 : p=0.72) and the diagnostic accuracy of each methods was comparable (TLB 100%, OLB 96%). The duration of hospital stay was significantly less in TLB (TLB 13days, OLB 22days : p=0.01). The duration of parenteral narcotics administration was also less for TLB(TLB 2.5days, OLB 5.2days, p=0.05). Meanwhile, the duration of chest tube drainage, the frequency of parenteral narcotic injection were not significantly different between two groups. Complications occurred in 2 among the TLB patients (6.67%) and 4 among the OLB patients (7.84%). There was no operative mortality in both groups. Conclusion: We concluded that TLB is a good alternative procedure to OLB in the diagnosis of diffuse infiltrative lung disease with lower morbidity and comparable diagnostic accuracy.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.481-487
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• 2017

The purpose of this study is to develop the hybrid sound-absorbing materials that is made from organic polyurethane sponge impregnated with inorganic binder solutions. The inorganic slurry which is made from ${\alpha}$-hemihydrate gypsum mixed with 60% water, and various additives including plasticizer are used as binder. The test specimens are prepared and tested for sound absorption performance by the impedance tube methods. From the test results, noise reduction coefficient(NRC) of development materials specimen bound by the inorganic binder slurry is 0.41. They are 2 times or more higher than commercial products specimens bound by organic materials only which have NRC values in the range of 0.14 to 0.28. The polyurethane sponge specimens impregnated with inorganic gypsum slurry binder have a good balance between performance and cost, and have proper properties in density, thermal conductivity, non-combustible, and absence of harmful substances as sound-absorbing internal boards for noise barrier wall. It is apparent that the good sound absorption materials can be produced according to the optimum mix design that is recommended from this study.

• Korean Journal of Veterinary Service
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• v.18 no.2
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• pp.133-151
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• 1995

During 2 years from Octorber 1992 to April 1994, prevalence of general respiratory diseases and atrophic rhinitis in the pig herds located in the Western Chungnam was investigated, and isolation of B. bronchiseptica was attempted for the pigs manifested with the clinical signs of atrophic rhinitis(AR). The isolates were characterized and identified in aspects of biochemical properties, antigenicity, drug sensitivity and pathogenicity. The results obtained through the experiments are summarized as follows; 1. During 2 years of investigation, the overall prevalence of the general respiratory diseases in the pi8 herds in Western Chungnam was 35.3%, consisting of 35.1% in the pig farms and 38.8% in a slaughter house. The prevalence by age groups accounts for 9.2% in adults, 44.7% in rearings and 25.3% in sucklings. By farm size, The highest prevalence of 56.5% was observed in the smallest farm with 1 to 200 heads. 2. The prevalence of clinical cases of artrophic rhinitis was recorded by 12.7% in the group that is the sows and piglets vaccinated, 28.9% in the group that is the sows only vaccinated and 39.8% in the group of the non-vaccinated groups. In the slaughter house, 53(24.8%) of 214 pigs examined exhibit the AR lesions. 3. A total of 189 strains of B. bronchiseptica were isolated from the pig herds. Isolation rates were 12.6% in the group that is the sows and piglets vaccinated, 34.1% in the group that is the sows only vaccinated and 45.7% in the group of the non-vaccinated groups. Isolation rate in the specimen from the slaughter house was 93( 43.5% ) of 214 pigs examined. Of the AR-non-vaccinated group, the piglets aged bet- ween 61 to 90 days revealed the highest isolation rate of 58.5%. 4. The titers of antibody against B. bronchiseptica were measured by tube agglutination test. The group that is the sow and piglet-vaccinated showed the highest titer of 640-2, 560 in sow and 640longrightarrow5, 120 in piglet. The group that is the sows only-vaccinated revealed 640-2, 560 in sows and 640-1, 280 in piglets. Both of the vaccinated groups showed 100% positive reaction. The group of the non-vaccinated sho-wed relatively lower titer of 0-1, 280 in both of sows and piglets. The positive rate of the sera obtained from the slaughter house was 53.3% with the antibody titer of 0-1, 280. 5. Biochemical and serological properities of 189 isolates were very similar to those of the reference B. bronchiseptical phase I type, indicating that most of isolates are B. bronchiseptica phase I type. 6. In antimicrobial drug susceptibility, 87.3% of 189 isolates was susceptible to chloramphenicol, 79.9%, to amikacin, 64.6%, to cephalothin and less than 35.4% to others. 7. In agar-gel immunodiffusion and SDS-PAGE analysis, the isolates presented the identical antigenicity and protein profiles to the reference standard strains. 8. The whole cells and bacterial filtrates of the isolates were inoculated to guinea pigs and mice. The isolates showed the hish pathogenicity and dermonecrotoxiciy.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.323-334
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• 2014

In this paper, experimental program and associated numerical study were carried out to evaluate the fire resistance of unprotected concrete-filled rectangular steel tubular (CFT) columns subjected to the standard fire. The key testing parameters included the length effect, the load ratio, and the sectional dimensions of the CFT columns. Temperature distribution and axial deformation of the CFT column specimens were measured and analyzed. Rather early local buckling of steel tubes was observed in all the specimens. This caused subsequent load transfer from steel tube to concrete, and eventually triggered concrete crushing, or complete loss of the load bearing capacity of the column. This implies that the limit state of local buckling as well as overall flexural buckling should be incorporated in fire design procedure. As expected, the fire resistance time of specimen with higher load ratio consistently lessened. The prediction of fire resistance time of unprotected CFT columns based on the limiting steel temperature in current design codes or the formula proposed by previous studies is slightly conservative compared to the fire test results available. To establish the finite element analysis model that can be used to predict the thermal and structural behaviour of unprotected CFT columns in fire, the fully coupled thermal-stress analysis was also tried by using the commercial code ABAQUS. The numerical results showed a reasonable global correlation with the experimental results.