• Environmental Engineering Research
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• 제15권2호
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• pp.57-62
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• 2010

The purpose of this study was to investigate the effect of mixing methods on the biodegradation of sorbed naphthalene and phenanthrene in soils. Biodegradation was initiated by inoculating Pseudomonas sp. KM1 into equilibrated soil slurry vials. Four different mixing methods, including no mixing, orbital shaking, rolling and rotating were utilized to enhance the biodegradation of both naphthalene and phenanthrene. The experimental results showed that the sorbed compounds were more effectively biodegraded with rolling and rotating mixing methods. The sorbed naphthalene concentrations were reduced to 0 mg/kg via the rolling and rotating methods. However, with no mixing and the orbital shaking methods, the sorbed naphthalene concentrations were comparatively high, ranging from 2.59 to 20.45 mg/kg. Similar trends were observed for the biodegradation of phenanthrene, but the concentrations remaining were higher than those of naphthalene, due to the limited bioavailability of the sorbed phenanthrene. The rolling and rotating mixing methods are suggested can distribute bacteria uniformly in the slurry system; improve the mass transfer rate and the probability of physical contact between bacteria and the sorbed contaminants, resulting in higher bioavailability of the contaminants.

• 한국세라믹학회지
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• 제35권5호
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• pp.458-464
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• 1998

Variations of reaction sequence of $Pb(Zn_{0.6}Mg_{0.4})_{1/3}Nb_{2/3}O_3$[PZMN] with precusor mixing methods were ex-amined using X-ray diffraction and dielectric characteristics. In the present study three different types of precursor mixing methods (oxide mixing PbO+$ZnNb_2O_6+MgNb_2O_6$[Zn+MN] and PbO+(Zn,Mg)$Nb_2O_6$[ZMN] precursor mixing) were adopted. When the oxide mixing method was used for the PZMN synthesis a Zn-rich perovskite phase and pyrochlore phase were formed. Compared with PbO+ZN+MN precursor mixing method the PbO-ZMN precursor led to a lowering of the formation temperature for perovskite sin-gle phase. These variation of composition and formation temperature of the perovskite phase were dis-cussed in terms of the difference in the solid-reaction requence between these three different types of pre-cursor mixing.

• 대한치과보철학회지
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• 제40권2호
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• pp.140-155
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• 2002

Void-free impression taking is important for the fabrication of accurate dental restorations. One of the essential properties of an impression material used for indirect fabrication of precision castings is the reproduction of the fine detail. The objective in this study was to determine the influence of mixing methods on the number of voids and surface detail reproduction. The number of voids and surface detail reproduction were evaluated with the steteomicroscope $SZ-PT^{(R)}$ and photographed. The results were as follows ; 1. In comparison of the void formation according to mixing methods of all impression materials, mechanical mixing was better than hand mixing and there was significant difference(p<0.05) 2. In comparison of the void formation according to hand mixing of alginate impression materials($TOKUSO\;A-1{\alpha}^{(R)},\;CAVEX\;IMPRESSIONAL^{(R)},\;AROMA \;FINE\;DF\;III^{(R)}$), there was no significant difference among alginate groups. But the number of void was increased in the order of $Panasil^{(R)}\;contact,\;TOKUSO\;A-1{\alpha}^{(R)},\;Permlastic^{(R)}$ light bodied and there was significant difference (p<0.05). 3. In comparison of the void formation according to mechanical mixing of alginate impression materials($TOKUSO\;A-1{\alpha}^{(R)},\;CAVEX\;IMPRESSIONAL^{(R)},\;AROMA FINE\;DF\;III^{(R)}$), there was no significant different among alginate groups. But the number of void was decreased in order of $TOKUSO\;A-1{\alpha}^{(R)},\;Permlastic^{(R)}light\;bodied,\;Panasil^{(R)}$ contact and there was significant difference (p<0.05). 4. In comparison of the surface detail reproduction according to mixing methods of 3 types of impression materials($TOKUSO\;A-1{\alpha}^{(R)},\;Permlastic^{(R)}\;light\;bodied,\;Panasil^{(R)}\;contact$), there was no significant difference between hand mixing and mechanical mixing method 5. The surface detail reproduction was only influenced by impression materials, and produced better in order of $TOKUSO\;A-1{\alpha}^{(R)},\;Panasil^{(R)}\;contact,\;Permlastic^{(R)}$ light bodied. There was significat difference among 3 type of impression materials(p<0.05). From the above results, void formation is influenced by mixing methods and surface detail reproduction is influenced by impression materials than mixing methods. Therefore, to fabricate accurate restorations, proper impression material and mechanical mixing method are more effective and available clinically.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 봄 학술발표회 논문집
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• pp.7-12
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• 1992

The aim of this study is to develop economical High-Strength and High-Quality Concrete, and to assure quality control of Concrete in the field. For this purpose, Five types of Mixing Methods are examined and the relationship between slump loss and slump recovery by transport is studied. As a result, workability and strength are dependent on the Mixing Method, although the Mixing proportions are same, Also, adding admixture in the field is proposed as an alternative to consider the relationship between slump loss and slump recovery.

• 대한치과기공학회지
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• 제38권4호
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• pp.263-272
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• 2016

Purpose: The purpose of this study is to measure and compare a degree of setting expansion of dental stone by time depending on the mixing methods and mixing ratios of dental stone, to compare the surface state of each specimen with the use of an optical camera with microscope, and thereby to provide a fundamental material for making dental prostheses. Methods: The test on setting expansion of dental stone is based on ISO 6873. With two different mixing ratios and three kinds of stone mixing methods, test groups were created, and a total of six types of specimens (N=30) were made. Based on the specimens, the setting expansion rate of each one was measured in each time slot of 24 hours, and the surface of the set stone was measured. Results: According to the analysis on setting expansion rate of stone, the setting expansion of the specimen that was created in the way of vacuum mixing at normal mixing ratio was 0.1944% at 120 minutes; the setting expansion of the specimen that was created in the way of vacuum mixing at the mixing ratio which was 40% higher than normal mixing ratio was 0.195% at 120 minutes; the setting expansion of the specimen that was created in the way of mixing with hands at normal mixing ratio and then removing bubbles in vacuum mixer was 0.196% at 120 minutes. Conclusion: The setting expansion rate of each dental stone specimen was significantly different with the lapse of time up to 24 hours(p<.001).

• 대한치과보철학회지
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• 제42권6호
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• pp.641-646
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• 2004

Statement of Problem. Temporary soft relining materials are used in a diverse clinical situations such as tissue conditioner, relining material, functional impression by varying its viscoelasticity. However, reproduction of consistent viscoelasticity has been not possible. Materials and methods. Considering setting mechanism of this material, this study has measured the effect of varying amount of void in dynamic viscoelasticity of soft relining material, with three different mixing methods. In each methods 10 specimens were made and subjected to dynamic viscoelastic test which were measured at specific times over period of 72 hours. Results. The analysis of the result shown that there was no statistically significant differences between different mixing methods. Conclusion. Different mixing methods had no effect over control of viscoelasticity of soft lining material. Further research is recommended for under similar oral environmental condition.

• 대한치과보철학회지
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• 제39권5호
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• pp.492-501
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• 2001

The use of alginate impression materials today is prevalent because of its efficiency and simplicity in clinical settings. Unfortunately, the simplicity of the procedure tends to lull the dentist into a sense of well-being, and lead him into using careless or sloppy technique. Alginate impression materials are used to fabricate diagnostic and preliminary casts, and the final cast. Incorrect use of this material is known to affect the accuracy of the final prosthesis. The purpose of this study was to compare the effect of different mixing methods of alginate impression material and tray adhesive on the accuracy of the stone cast produced by each method. A total of 30 stone casts were produced by using 3 different types of mixing methods (10 stone cast for each mixing method, respectively). The first method utilized an automatic-mixing machine to mix alginate while the second method was carried out manually, strictly following manufacturer's instructions. The third method also involved manual mixing, but did not follow the manufacturer's instructions and was done in a random fashion. Also, 20 additional stone casts were produced by using alginate with or without tray adhesives were included in the study to evaluate effects of tray adhesives on the accuracy of alginate impression. 10 stone casts were produced by adding tray adhesives to the interior surface of the impression tray prior to taking the impression. The other 10 excluded this step. A total of 50 stone casts were analyzed by the three-dimensional measuring machine to measure and compare the dimensional changes of the impression material of each group. The results are as follows. 1. No significant difference was found between the automatic mixing group and the manually-mixing group(p>0.05). 2. For the group that followed manufacturer's instructions, less dimensional changes were record ed than the group that didn't in measuring distanced 4(p<0.05). 3. The group that used tray adhesives showed less dimensional changes(p<0.05). The findings revealed that mechanical methods of mixing alginate impression materials had little influence on dimensional changes. However, it is proven that following manufacturers instructions in alginate impression taking is an important step in acquiring accurate impressions and tray adhesives may play an important role in enhancing the results.

• 한국전산유체공학회지
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• 제22권1호
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• pp.1-7
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• 2017

The mixing of water and chemicals is an important process in the water purification plant. In this paper, we compare PDM(pump diffusion mixer) and hydraulic mixer at the basin in the mixing process. The proper flow rates are predicted and compared in both mixers using CFD technique. As a result, the flow rate of purifier chemical liquid should be 5% of that of water for the optimal performance of mixing process. The characteristics of the two mixing methods are compared with each other for strong and weak points on the operation of the purification system, discussed in the view point of CFD simulations.

• 한국건축시공학회지
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• 제15권3호
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• pp.351-357
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• 2015

Fiber reinforced concrete (FRC) has been successfully used to enhance the flexural toughness of concrete. As fibers are randomly oriented in FRC, they sometimes produce clumps that reduce the mechanical performance, and a properly chosen mixing protocol can be a way to minimize this problem. In this research, the effects of mixing method on the mechanical properties of FRC were investigated. The compressive strength, flexural strength, and flexural toughness were measured using three different mixing methods. It was shown from the results that the compressive strength and peak flexural load were not affected by changes in mixing method. However, in terms of flexural toughness, the changes in mixing method clearly affected the flexural toughness of FRC. The truck-mixed FRC outperformed two pan-mixed FRCs.

• 헤리티지:역사와 과학
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• 제53권1호
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• pp.34-51
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• 2020

성남 고등동 회곽묘는 한 지역에서 다른 시기에 제작된 6기의 회곽묘가 발굴되었으며, 회곽묘 조성에 사용된 삼물회의 다양한 제작 기법이 확인되었다. 삼물회의 제작 기법을 규명하기 위하여 고문헌 기록을 바탕으로 석회 원료와 제작 기법 및 배합 방법을 고찰하였다. 조선시대 고문헌에는 석회의 원료 중 저품위 석회석을 사용한 기록과 배합 재료로 황토와 백토, 기와 가루 등과 같은 석회의 강도를 향상시킬 수 있는 포졸란 물질 사용에 대한 기록이 남아있다. 또한 삼물회의 다양한 배합 방법이 기록되어 있어 이에 대한 재현 실험을 바탕으로 석회 원료, 배합 재료, 배합 비율에 따른 삼물회 제작 기법 분석이 요구되었다. 조선시대 전기에는 석회를 다방면으로 사용하였으나 공급이 적고 기술적인 미숙함으로 지속적인 문제가 발생하였으며, 조선시대 후기에 이르러 대량 생산됨과 함께 석회 제작 기술이 발달하였다. 16세기와 18세기 회곽묘 삼물회의 제작 기법 분석을 바탕으로 고문헌에 기록된 배합비와 배합 방법들이 적용된 것을 알 수 있었으며, 회곽묘 삼물회는 시기에 따라 석회의 품질이 변화하였고 배합 재료 또한 변화됨에 따라 배합 비율이 다르게 나타나는 것으로 판단된다. 회곽묘 삼물회의 배합 비율은 시기에 따라서 변화하였으며, 주례와 가례를 기준으로 정해진 배합 방법으로 제작되었기 때문에 회곽묘 삼물회의 제작 기법에 대한 과학적 분석 자료가 지속적으로 구축된다면 회곽묘 편년 연구에 도움이 될 것으로 기대된다.