• International Journal of Highway Engineering
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• v.7 no.2 s.24
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• pp.33-43
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• 2005

This paper describes a new approach to minimize the amount of shrinkage cracking in cement treated base(CTB). CTB is a stiffness base having lots of merits such as higher rutting resistance, minimizing fatigue cracking, and the ability to distribute upper loads. However, It is not applied to asphalt pavement system in Korea because of possible cracks caused by dry shrinkage. The goal of this study is the development of cement treated base with lower shrinkage for preventing reflection cracks and rutting. After identifying factors affecting dry shrinkage and analyzing mechanism of each admixture, the laboratory and field tests were designed and performed. Through the preliminary tests, the mix design containing 25 percent o( fly ash and 7 percent of cement was suggested. This mix design was satisfied with strength for Korea specification standard. According to the results considering strength, shrinkage, and economical efficiency, two mix designs were selected; 1) containing 25 percent of fly ash and 2) containing 25 percent of fly ash with 10 percent of expensive additive. For field test based on the result of laboratory test, the optimized alternative in cement treated base with lower shrinkage was the mix design containing 25 percent of fly ash with 10 percent of expansive additive.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.593-610
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• 1996

The objective of this paper was to evaluate the shear bond strength of luting glass ionomer cement with defferent calcium based solution treatment on dentin surface. 120 extracted human teeth were classified into 12 group based on presence of smear layer on dentin surface and type of treatment solution. Smear layer remove on dentin surface was done using 6% citric acid for 60 seconds. Five different dentin surface treatment solutions(calcium acetate, calcium carbonate, clacium chlorided, calcium hydroxide, and calcium phosphate) were evaluated in this study. After surface modification, metal ring(inner diameter : 3mm, depth : 1mm) was placed to expose the same dentin surface area and inner space was filled with luting glass ionomer cement according to the recommended procedure for stadard clinical procedure. The shear bond strength of glass ionomer cement was determined after 24 hours. SEM was used for the evaluation of the surface morphologic changes and EDAX analysis was done for determination of the change of the calcium contents of treated dentin. Follwing conclusion can be drawn : 1. In the group of the dentin surface with smear layer, the calcium carbonate solution was the most effective for the increase of the clacium content and the shear bond strength of glass ionomer cement to dentin surfaces. 2. In the group of the calcium carbonate treated dentin with msear layer, the shear bond strength was increased twice compared to the control group and cohesive failure mode was observed. 3. The shear bond strength of cement was increased significantly be the removal of smear layer using 6% citric aicd. However, additional calcium solution treatments were not effective for further bond strength increase. 4. The shear bond strength of cement was significantly improved by both of the removal of smear layer and the calcium solution treatment, and the former was more effective for bond strength improvement. 5. The smear layer removed/calcium solution treated groups showed dentinal tubule obstruction and crystal attachment in SEM evaluation. However, the shear bond strengths of these groups were not increased compared to the smear layer removed/no dentin treatment group.

• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.65-73
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• 2013

The purpose of this study is to confirm strength and effectiveness of grouting of the sand treated with bacteria. In order to analyze the cementation of sand treated with bacteria, five types of specimens(Not treated, Cement 2% treatment, Cement 4% treatment, Cement 2% + $CaCO_3$ 2% treatment and $CaCO_3$ 4% treatment) were made. Unconfined compressive strength tests were done on $D\;5cm{\times}H\;10cm$ specimens and biogrouting tests were performed on $D\;6cm{\times}H\;12cm$ specimens to observe the effectiveness of grouting with bacteria. As a result, Cement 2% + $CaCO_3$ 2% treatment was found to be the most effective in terms of the unconfined compressive strength.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.65-72
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• 2006

This study is about the estimation of the mechanical properties of cement grout material using a magnetic field treated water instead of tap water. The water that passed through a magnetic system is called MFTW. Similar research indicates that 5% of cement dosage can be saved by decreasing bleeding of concrete and improving resistance to freezing. The reason why MFTW can improve characteristics of concrete can be explained by molecular structure of water. Magnetic force makes water clusters into single molecule or small ones. Hence, the activity of water is improved by the magnetic force. While hydration of cement particles is on progress, the MFTW can penetrate the core region of cement particles more easily. Therefore, the hydration can be carried out more efficiently and the compression strength of concrete is highly improved. The sample of the sodium silicate cement grout's homogel using the MFTW results in highly compressive strength increases in compressive strength approximately from 20% to 50%.

• Restorative Dentistry and Endodontics
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• v.39 no.4
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• pp.296-302
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• 2014

Objectives: It is difficult to achieve adhesion between resin cement and zirconia ceramics using routine surface preparation methods. The aim of this study was to evaluate the effects of $CO_2$ and Er:YAG laser treatment on the bond strength of resin cement to zirconia ceramics. Materials and Methods: In this in-vitro study 45 zirconia disks (6 mm in diameter and 2 mm in thickness) were assigned to 3 groups (n = 15). In control group (CNT) no laser treatment was used. In groups COL and EYL, $CO_2$ and Er:YAG lasers were used for pretreatment of zirconia surface, respectively. Composite resin disks were cemented on zirconia disk using dual-curing resin cement. Shear bond strength tests were performed at a crosshead speed of 0.5 mm/min after 24 hr distilled water storage. Data were analyzed by one-way ANOVA and post hoc Tukey's HSD tests. Results: The means and standard deviations of shear bond strength values in the EYL, COL and CNT groups were $8.65{\pm}1.75$, $12.12{\pm}3.02$, and $5.97{\pm}1.14MPa$, respectively. Data showed that application of $CO_2$ and Er:YAG lasers resulted in a significant higher shear bond strength of resin cement to zirconia ceramics (p < 0.0001). The highest bond strength was recorded in the COL group (p < 0.0001). In the CNT group all the failures were adhesive. However, in the laser groups, 80% of the failures were of the adhesive type. Conclusions: Pretreatment of zirconia ceramic via $CO_2$ and Er:YAG laser improves the bond strength of resin cement to zirconia ceramic, with higher bond strength values in the $CO_2$ laser treated samples.

• Journal of Trauma and Injury
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• v.28 no.3
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• pp.202-205
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• 2015

Purpose: Pulmonary cement embolization after vertebroplasty is a well-known complication. The reported incidence of pulmonary cement emboli after vertebroplasty ranges frome 2.1% to 26% with much of this variation resulting from which radiographic technique is used to detect embolization. Onset and severity of symptoms are variable. Case description: We present the case of a 83-year-old women who underwent fourth lumbar vertebroplasty and subsequently had dyspnea several days later. Posteroanterior chest radiography showed multiple linear densities. Computed tomography of thorax revealed also multiple bilateral, linear hyperdensities within the lobar pulmonary artery branches are detected in axial and coronal views. Literature Reviews: Operative management of vertebral compression fractures has included percutaneous vetebroplasty for the past 25 years. Symptoms of pulmonary cement embolism can occur during procedure, but more commonly begin days to weeks, even months, after vertebroplsty. Most cases of pulmonary cement emboli with cardiovascular and pulmonary complications are treated nonoperatively with anticoagulation. Endovascular removal of large cement emboli from the pulmonary arteries is not without risk and sometimes requires open surgery for complete removal of cement pieces. Conclusion: Pulmonary cement embolism is a potentially serious complication of vertebroplasty. If a patient has chest pain or respiratory difficulty after the procedure, chest radiography and possibly advanced chest imaging studies should be performed immediately.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.297-302
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• 2001

SRC pier at KTE 6-1 construction area is a very important structure. Precise control of quality is needed. This pier has 3.50m$\times$3.73m section and 38.20m length. So this structure must be treated as mass concrete and thermal crack caused by hydration heat should be controled. In this project belite cement concrete is used to control the thermal crack. As a result of adapting belite cement concrete perfect control is achieved. Finally, hydration heat FEM analysis of horizontal element is executed for Ordinary Portland Cement concrete and belite cement concrete. In comparison of two results, it is confirmed that using low heat portland cement concrete is necessary.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.73-78
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• 2001

Soundness evaluation of a structure being constructed under the sea is usually difficult. In this study, a cross-hole sonic logging(CSL) which have been used for non-destructive test of concrete piles is adopted for the integrity test and monitoring of DCM(deep cement mixing) treated soils. Chemical and physical characteristics of raw ground materials are analysed to delineate ground environmental effects on the strength of DCM treated soils. In order to convert cross-hole sonic logging data into compressive strength, correlations between compressive strengths and wave velocities of core samples have been obtained. It is found that there is little effect of ground environment on the strength of the DCM treated soils, and the density distribution of core samples and cross-hole logging data show that a defective zone may exist in the DCM treated soils. With the time lapse, however, the defective zone has been cured and consequently, compressive strength of the DCM treated soils increases and satisfies the design parameter. From this study it can be concluded that the cross-hole sonic logging can be used for the integrity test as well as monitoring the curing stage of the structures, successfully.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.249-256
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• 2015

PURPOSE. The aim of this study was to evaluate the effects of atmospheric plasma (APL) versus conventional surface treatments on the adhesion of self-adhesive resin cement to Ti-6Al-4V alloy. MATERIALS AND METHODS. Sixty plates of machined titanium (Ti) discs were divided into five groups (n=12): 1) Untreated (CNT); 2) Sandblasted (SAB); 3) Tribochemically treated (ROC); 4) Tungsten CarbideBur (TCB); 5) APL treated (APL). SEM analysis and surface roughness (Ra) measurements were performed. Self-adhesive resin cement was bonded to the Ti surfaces and shear bond strength (SBS) tests, Ra and failure mode examinations were carried out. Data were analyzed by one-way analysis of variance and chi-squared test. RESULTS. The lowest SBS value was obtained with CNT and was significantly different from all other groups except for APL. The ROC showed the highest SBS and Ra values of all the groups. CONCLUSION. It was concluded that the effect of APL on SBS and Ra was not sufficient and it may not be a potential for promoting adhesion to titanium.

• The Journal of Internal Korean Medicine
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• v.36 no.1
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• pp.49-57
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• 2015

Objectives : The purpose of this report is to investigate the effect of Taeeumin Cheonghyeolgangki-tang on chronic contact dermatitis caused by cement. Methods : A 52-year-old male patient was diagnosed with contact dermatitis with the Questionnaire for Sasang Constitutional Classification-II (QSCC-II) as well as the four methods of diagnosis (四診), and treated with Taeeumin Cheonghyeolgangki-tang (qīngxuèjiàngqí-tāng). We observed redness and scaling on both palms, and recorded photographs of any changes during the inpatient and outpatient treatment period. Results : The symptoms of contact dermatitis on both palms were significantly improved. Scaling and cracked skin disappeared and the redness almost resolved. Conclusions : Therefore, Taeeumin Cheonghyeolgangki-tang ( qīngxuèjiàngqí-tāng ) is effective on chronic contact dermatitis caused by cement.