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근단 협착부 직경, 세척액 주입속도, 주사침 말단의 형상이 치근단에 작용하는 압력에 미치는 영향
이창하(Chang-Ha Lee),조설아(Seol-Ah Jo),임범순(Bum-Soon Lim),이인복(In-Bog Lee) 대한치과재료학회 2019 대한치과재료학회지 Vol.46 No.2
The purpose of this study was to evaluate the effects of apical constriction (AC) diameter, irrigant flow rate, and needle tip design on apical pressure (AP) during the root canal irrigation. Five extracted human mandibular premolars were instrumented up to #35 (0.06 taper) using nickel-titanium rotary instruments. AC was determined at 1 mm from the apical foramen. Three needles with different tip designs (notched, side-vented, and flat) were placed 3 mm from AC. APs were measured with varying flow rates of 0.05, 0.1, 0.2, and 0.3 mL/s. The AC diameter of the teeth was enlarged to #40 and #45 (0.06 taper) successively, and the aforementioned measurement procedure was repeated (n=5). When the other conditions were controlled, AP increased with decreasing AC diameter or increasing irrigant flow rate, and the AP of flat needle was the highest, followed by notched, and side-vented needle (p<0.05). The APs with 0.05 mL/s flow rate were lower than central venous pressure (5.88 mmHg) for all conditions. Under the conditions of the present study, flat needle is not recommended in narrow AC (0.35 mm), as the value of the AP with a flow rate of 0.05 mL/s is similar to the central venous pressure. However, in AC diameter of >0.35 mm, open-end (notched or flat) needles can be used to improve irrigant replacement in the apical portion using a flow rate of 0.05 mL/s.
페로니켈슬래그 미분말 및 혼화재의 복합사용이 VR 하수관 강도발현에 미치는 영향분석
남상구(Sang-Koo Nam),정태준(Tae-Jun Chung),조설아(Seol-Ah Jo),유정환(Jeong-Hwan Yoo),박상순(Sang-Soon Park) 한국건설순환자원학회 2018 한국건설순환자원학회 논문집 Vol.6 No.3
본 논문에서는 페로니켈슬래그 미분말 및 혼화재의 복합사용이 VR 하수관 강도발현에 미치는 영향분석에 관한연구를 실시하였다. 치환율을 변수로 시험을 실시하였으며, 휨강도 및 압축강도의 결과분석과 SEM 분석을 통한 강도발현 성능연구를 실시하였다. 휨강도 및 압축강도, SEM을 통한 미시적 분석을 통해, 각 경우 별 상관관계를 도출 할 수 있었다. 치환율은 OPC 질량대비 20%, 30%를 구분하여 페로니켈 슬래그 미분말 및 혼화재를 일정 비율로 치환하여 실시하였다. 치환율 20%일 경우 강도발현성능이 우수한 것으로 나타났으며, 휨 강도와 압축강도는 페로니켈 슬래그 미분말, 생석회, 석고, 염화칼슘을 혼화재로 복합사용 하였을 때 강도발현 성능이 가장 우수하였으며, 조밀한 미세구조 형태를 나타냈고, 재령 28일 이후에도 점진적 강도발현가능성이 보인다. In this paper, the effects of ferronickel slag powder and admixture on the strength of VR sewer pipe were analyzed. the substitution rate was tested as a variable, and the strength development was studied through the flexural strength, compressive strength and using SEM microscopic analysis. bending strength, compressive strength results and micro analysis using SEM showed the correlation in each case. the substitution rates were 20% and 30% relative to the mass of the OPC respectively, and were substituted according to a constant ratio of ferronickel slag fine powder and mixture. when the substitution ratio was 20%, the strength development was excellent. also, bending strength and compressive strength were the best when the ferronickel slag fine powder, quicklime, gypsum and calcium chloride were used as the admixture, dense microstructural patterns appeared. the possibility of progressive strength development is shown after 28 days.