• Journal of Environmental Science International
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• v.2 no.1
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• pp.61-72
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• 1993

Result of this study indicate that two criteria must be met in order to have effective macrocycle-mediated transport in these emulsionsystem. First, one must effective extraction of the post transition metals, $Cd^{2+}$. $Pb^{2+}$ and $Hg^{2+}$ , into toluene membrane. The effectiveness of this extraction is greatest if log K values for the metal-macrocycle interaction is large. Second, the ratio of the log K values for the metal ion-receiving phase to the metal ion-macrocycle interaction must be large enough to ensure quantitative stripping of the metal ion at the toluene phase interface. Control of the first step can be obtained by appropriate selection of macrocycle donor atom, substituents, and cavity radius. The second step can be controlled by selecting the proper complexing agent for inclusion in the receiving phase. The order of the transport, when using the several $A^-$ species such as $SCN^-$, $1^-$, $Br^-$ and $Cl^-$ is the order of the changing degree of solvation for $A^-$ and the transport of the metals is also affected by the control of concentration for receiving species because of solubility-differences. In this study, we can seperate each single metal ion from the mixture of $Cd^{2+}$, $Pb^{2+}$, and $Hg^{2+}$ ions by using the toluene membranes controlled by optimized conditions. Transport of the single metal is also very good, and alkaline and alkaline earth metals as interferences ions did not affect the seperation of the metals in this macrocycle-liquid membrances but transition metal ions were partially affected as interferences for the post transition metal ions.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.602-618
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• 1996

The purpose of this study was to investigate the effect of acid treatment of fluoride applied dentin surface with various concentrations of phosphoric acid for various periods of time on dentin bonding. Dentin specimens prepared from freshly extracted bovine mandibular anterior teeth were divided into fluoridated and nonfluoridated groups. Specimens of nonfluoridated group were pretreated with 10% phosphoric acid for 15 seconds. Those of fluoridated groups were treated with 2% sodium fluoride or 2% stannous fluoride solution for 5 minutes and stored in $37^{\circ}C$ distilled water for 3 days, followed by phosphoric acid treatment. The concentrations of phosphoric acid were 10%, 32% or 50% and the treatment periods of time were 15, 30 or 60 seconds. All the specimens were bonded with All Bond$^{(R)}$ 2 and Bisfil$^{TM}$ composite resin. After bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, tensile bond strengths of each specimens were measured and the pretreated dentin and the fractured dentin surfaces were examined under the scanning electron microscope. The results were as follows : The tensile bond strengths from the fluoridated groups were significantly lower than those from the nonfluoridated group when the concentrations of phosphoric acid and the treatment periods of time were equal in all the groups (p<0.05). In general, the higher the concentration of phosphoric acid and the longer the treatment period of time for acid etching on the fluoride applied dentin surface, the higher were the bond strength values. Recovery of bond strength of the dentin bonding agent was better in the NaF applied group than in the $SnF_2$ applied one. SEM findings of NaF applied and $SnF_2$ applied dentin surfaces demonstrated reaction product-covered and partially or completely obstructed dentinal tubules. SEM findings of dentin surfaces fluoridated for 5 minutes followed by etching showed wider tubular openings and more clean dentin surfaces when dentin was etched with higher concentration of phosphoric acid for longer period of time. On the SEM observations of the fractured dentin-resin interface, the etched specimens of fluoridated group showed an adhesive failure mode when the concentration of phosphoric acid and the treatment period of time were same as in the nonfluoridated group. As the concentration of phosphoric acid and the treatment period of time increase during acid etching, the cohesive failure area increased. However, excessive acid etching caused adhesive failure.

• Composites Research
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• v.20 no.1
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• pp.23-31
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• 2007

In order to improve the mechanical properties of jute fiber/polypropylene(PP) composites, the property change with the addition of a coupling agent, maleic anhydride polypropylene(MAPP) was examined experimentally. The maleated coupler acts as an intermediate to chemically connect the polar nature of the fiber and non-polar nature of the polyolefin polymer resin. Furthermore, the decrease in viscosity of the resin which results from the melting point reduction by the MAPP, leads to an increase of contact area with the fiber interface. We discussed the improvement of the PP composite blend of the maleated coupler with the 80mm jute long fiber mat in conjunction with the change of physical parameters in the thermoplastic resin. We confirmed the extent of contribution to the mechanical physical enhancement by using the following parameters: melting flow index(MI) and viscosity, contact angle, thickness of the composite, interfacial shear strength and morphology observation etc. Especially it was observed that the MI and viscosity, MAPP mixture had a very strong relationship with the tensile and flexural strength and modulus, and interfacial shear strength(IFSS).

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.154-167
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• 2014

The results of this study conducted to identify the substance, regional characteristics or landscaping of Namwon Yonghogugok, which is the only valley of Jiri Mountain, based on Kim Samun's 'Yonghokugok-Gyeongseungannae(龍湖九曲景勝案內)', 'Yongseongji(龍城誌)' and position, meaning of letters carved and projection technique by ArcGIS10.0 on the rocks are as below. The feature landscapes of the canyon of Yonghogugok, which is an incised meander and one of the Eight beautiful scenery of Namwon, ponds, cliffs and rocks generated with metamorphic rocks and granites weathered by rapids torrents. As a result of measuring the GPS coordinates of the letters carved on the rocks, excluding the 3 Gok Hakseoam and the distances based on the origin and destination of the letters carved on the rocks using the API(Application Programming Interface) function of Daum map, the total distance of Yonghogugok was 3.5km and the average distance between the each Gok was 436.5m. It is assumed that Yonghogugok was designated by Sarim(士林) of the Kiho School(畿湖學派) related to Wondong Hyangyak(元洞鄕約) which is the main agent of Yonghojeongsa(龍湖精舍), the forerunner of Yonghoseowon(龍湖書院), between the late Joseon Dynasty and the early Japanese colonial era, in 1927. Its grounds are the existence of Yonghoyeongdang mentioned on 'Yonghojeongsilgi'(龍湖亭實記), records of 'Haeunyugo(荷隱遺稿)', 'Yonghopumje(龍湖品題)' of Bulshindang(佛神堂), 'Yonghojeongsadonggu Gapjachun(龍湖精舍洞口 甲子春)' letters carved on the rocks and 'Yonghogugok-Shipyeong(龍湖九曲十詠)' posted on Mokgandang of Yonghoseowon. Comprehensively considering the numerous poetry society lists carved on the stone wall of Punghodae(風乎臺), the Sixth Gok Yuseondae, its stone mortar, 'Bangjangjeildongcheon(方丈第一洞天)' of Bulshindang and Gyoryongdam(交龍潭), the Yonghoseokmun(龍湖石門) letters carved on the rocks, Yeogungseok adjacent to the First Gok and Fengshui facilities, centered on Yonghoseowon and Yonghojeong, Yonghogugok can be understood as a unique valley culture formed with the thoughts of Confucianism, Buddhism, Taoism and Fengshui. 'Yonghogugok-Gyeongseungannae' provides very useful information to understand the place name, called by locals and landscaping aspects of Yonghogugok in the late Joseon Dynasty. In addition, the meaning of "Nine dragons" and even though 12 chu(湫: pond) of Yonghogugok Yongchudong including Bulyeongchu, Guryongchu, Isuchu, Goieumchu and Daeyachu are mentioned on Yongseongji, a part of them cannot be confirmed now. Various place names and facilities relevant to Guryong adjacent to Yonghogugok are the core of the place identity. In addition, the accurate location identification and the delivery of the landscaping significance of the 12 ponds is expected to provide landscaping attractiveness of Yonghogugok and become very useful contents for landscaping storytelling and a keyword of storyboard.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.166-179
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• 1999

Apical sealing is essential for the success of surgical endodontic treatment. Root-end cavity is apt to be contaminated with moisture or blood, and is not always easy to be dried completely. The purpose of this study was to evaluate the influence of dry methods of retrocavity on the apical seal in endodontic surgery. Apical seal was investigated through the evaluation of apical leakage and adaptation of filling material over the cavity wall. To investigate the influence of various dry methods on the apical leakage, 125 palatal roots of extracted human maxillary molar teeth were used. The clinical crown of each tooth was removed at 10 mm from the root apex using a slow-speed diamond saw and water spray. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. After removing of the coronal 2 mm of filling material, the access cavities were closed with Cavit$^{(R)}$. Two coats of nail polish were applied to the external surface of each root. Apical three millimeters of each root was resected perpendicular to the long axis of the root with a diamond saw. Class I retrograde cavities were prepared with ultrasonic instruments. Retrocavities were washed with physiologic saline solution and dried with various methods or contaminated with human blood. Retrocavities were filled either with IRM, Super EBA or composite resin. All the specimens were immersed in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using one-way ANOVA and Duncan's Multiple Range Test. To evaluate the influence of various dry methods on the adaptation of filling material over the cavity wall, 12 palatal roots of extracted human maxillary molar teeth were used. After all the roots were prepared and filled, and retrograde cavities were made and filled as above, roots were sectioned longitudinally. Filling-dentin interface of cut surfaces were examined by scanning electron microscope. The results were as follows: 1. Cavities dried with paper point or compressed air showed less leakage than those dried with cotton pellet in Super EBA filled cavity (p<0.05). However, there was no difference between paper point- and compressed air-dried cavities. 2. When cavities were dried with compressed air, dentin-bonded composite resin-filled cavities showed less apical leakage than IRM- or Super EBA-filled ones (p<0.05). 3. Regardless of the filling material, cavities contaminated with human blood showed significantly more apical leakage than those dried with compressed air after saline irrigation (p<0.05). 4. Outer half of the cavity showed larger dentin-filling interface gap than inner half did when cavities were filled with IRM or Super EBA. 5. In all the filling material groups, cavities contaminated with blood or dried with cotton pellets only showed larger defects at the base of the cavity than ones dried with paper points or compressed air.

• Korean Journal of Cognitive Science
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• v.12 no.3
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• pp.29-46
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• 2001

This study attempted to demonstrate that the integration of the two premises in linear syllogism is mediated by the middle term the term that is repeated in the two premises. In Experiment 1. we examined whether representing the middle term is more important than representing the end terms. We asked a question to each premise. Depending on the order of the questions either the two end terms or the middle term became the answer in both premises. Participants solved the problems better when the middle term became the answer suggesting that it is more important to represent the middle term than the end terms. In Experiment 2 we examined whether additional processing is needed for the integration beyond establishing co-referential link through the middle term. We pronominalized the middle term in the second premise and provided two kinds of information to disambiguate the pronoun. In the direct information condition we provided information about who the pronoun is whereas in the indirect information condition we provided information about the relative location of the pronoun. Participants solved the problems more quickly in the indirect information condition than in the direct information condition indicating that mere co-referential link was not enough and that the relative location of the middle term needs to be computed for the integration of the two premises.

• Restorative Dentistry and Endodontics
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• v.27 no.2
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• pp.150-157
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• 2002

One of the latest concepts in bonding are "total etch", in which both enamel and dentin are etched with an acid to remove the smear layers, and "wet dentin" in which the dentin is not dry but left moist before application of the bonding primer Ideally the application of a bonding agent to tooth structure should be insensitive to minor contamination from oral fluids. Clinically, contaminations such as saliva, gingival fluid, blood and handpiece lubricant are often encountered by dentists during cavity preparation. The aim of this study was to evaluate the effect of contamination by hemostatic agents on shear bond strength of compomer restorations. One hundred and ten extracted human maxillary and mandibular molar teeth were collected. The teeth were removed soft tissue remnant and debris and stored in physiologic solution until they were used. Small flat area on dentin of the buccal surface were wet ground serially with 400, 800 and 1200 abrasive papers on automatic polishing machine. The teeth were randomly divided into 11 groups. Each group was conditioned as follows : Group 1: Dentin surface was not etched and not contaminated by hemostatic agents. Group 2: Dentin surface was not etched but was contaminated by Astringedent$^{\circledR}$(Ultradent product Inc., Utah, U.S.A.) Group 3: Dentin surface was not etched but was contaminated by Bosmin$^{\circledR}$(Jeil Pharm, Korea.). Group 4: Dentin surface was not etched but was contaminated by Epri-dent$^{\circledR}$(Epr Industries, NJ, U.S.A.). Group 5: Dentin surface was etched and not contaminated by hemostatic agents. Group 6: Dentin sorface was etched and contaminated by Astringedent$^{\circledR}$. Group 7 : Dentin surface was etched and contaminated by Bosmin$^{\circledR}$. Group 8: Dentin surface was etched and contaminated by Epri-dent$^{\circledR}$. Group 9: Dentin surface was contaminated by Astringedent$^{\circledR}$. The contaminated surface was rinsed by water and dried by compressed air. Group 10: Dentin surface was contaminated by Bosmin$^{\circledR}$. The contaminated surface was rinsed by water and dried by compressed air. Group 11 : Dentin surface was contaminated by Epri-dent$^{\circledR}$. The contaminated surface was rinsed by water and dried by compressed air. After surface conditioning, F2000$^{\circledR}$ was applicated on the conditoned dentin surface The teeth were thermocycled in distilled water at 5$^{\circ}C$ and 55$^{\circ}C$ for 1,000 cycles. The samples were placed on the binder with the bonded compomer-dentin interface parallel to the knife-edge shearing rod of the Universal Testing Machine(Zwick Z020, Zwick Co., Germany) running at a cross head speed or 1.0 mm/min. Group 2 showed significant decrease in shear bond strength compared with group 1 and group 6 showed significant decrease in shear bond strength compared with group 5. There were no significant differences in shear bond strength between group 5 and group 9, 10 and 11.