• 자원리싸이클링
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• 제32권6호
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• pp.10-17
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• 2023

칼슘실리케이트 시멘트(Calcium silicate cement, CSC)는 친환경 저탄소 시멘트로써 최근에 많은 연구가 진행되고 있다. 하지만 이산화탄소 반응 활성화와 시료 handling을 위하여 사전경화 단계를 진행하여야하는 어려움이 있다. 본 연구에서는 CSC에 칼슘설포아루미네이트(Calcium sulfoaluminate, CSA) 속경시멘트를 혼합하여 초기강도 발현으로 사전경화 없이 사용할 수 있는 CSC의 확대적용 가능성을 살펴보고자 하였다. 이를 위하여 이산화탄소 분위기에서 CSC 와 CSA 속경성 시멘트 혼합비율 변화에 따른 압축강도와 Q-XRD 광물특성 함량 변화를 측정하였다. 압축강도 측정결과, CSC 50% 조건에서 3일과 7일 압축강도가 각 각 14.18MPa과 22.98MPa로 1종시멘트 KS규격을 만족하였다. 광물특성 분석을 통하여 이산화탄소 반응생성물인 calcite 광물이 증가하여 강도발현에 기여했음을 알 수 있었다. 7일 경과 후에도 수화광물인 dicalcium silicate 및 yeelimite광물뿐 아니라, 이산화탄소와 반응하지 않은 rankiniten 및 pseudowollastonite 광물이 다량 관찰되어 7일이후의 강도발현 가능성을 확인하였다.

• 대한치과기공학회지
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• 제37권4호
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• pp.205-212
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• 2015

Purpose: The objective of this study was to compare the surface roughness according to polishing process in conventional laboratory techniques used for polishing three different acrylic denture base resins. Materials and methods: Specimen preparation and surface polishing procedures were conducted to manufacturer's recommendation with three heat-polymerized denture base resins. Surface roughness and gloss were measured by a contact type tester and a LED gloss checker using thickness 2 mm and diameter 10 mm. There were five specimens for each acrylic resin material and polishing procedures. Mean average surface roughness (Ra) values of each specimen group were analyzed using a one-way ANOVA analysis of variance and Scheffe's post hoc test. Surfaces after surface roughness and gloss testing according to each polishing process were evaluated under a stereoscopic microscope. Results: The highest mean average surface roughness was measured($Ra=2.43{\pm}0.47$) for surfaces finished with a denture tungsten carbide bur in Triplex. The lowest surface roughness values ($Ra=0.11{\pm}0.07$) were determined in Vertex polished with a lathe. In addition, all materials revealed that surface roughness determined highly in HP1 and HP2 than other procedures. All correlation between surface roughness and gloss showed highly with three heat-polymerized resins. Specially, topmost correlation revealed than other material in Triplex. Significant differences in mean average surface roughness were found between polishing process used high speed lathe and low speed hand-piece. Conclusion: Laboratory polishing used to high speed was found to produce the smoothest surface of heat-polymerized denture base acrylic resin. Therefore, we recommended that high polishing process need to get smooth surface.

• 대한기계학회논문집A
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• 제20권2호
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• pp.408-413
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• 1996

A self-diagnostic, air-damped, piezoresitive, cantilever-beam microaccelerometer has been designed, fabricated and tested for applications to automotive electronic airbag systems. A skew-symmetric proof-mass has been designed for self-diagnostic capability and zero transverse sensitivity. Two kinds of multi-step anisotropic etching processes are developed for beam thickness control and fillet-rounding formation, UV-curing paste has been used for sillicon-to-glass bounding. The resonant frequency of 2.07kHz has been measured from the fabricated devices. The sensitivity of 195 $\mu{V}$/g is obtained with a nonlinearity of 4% over $\pm$50g ranges. Flat amplitude response and frequency-proportional phase response have been obserbed, It is shown that the design and fabricaiton methods developed in the present study yield a simple, practical and effective mean for improving the performance, reliability as well as the reproducibility of the accelerometers.

• 대한간호학회지
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• 제24권3호
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• pp.327-344
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• 1994

It is needed that nursing scholars in Korea should understand the philosophy and perspectives of oriental medicine, and then explore the possiblities of theory building which can be a Korean’s unique nursing theory. With the assumption of this kind of work can be achieved by cooperation of oriental medicine and nursing areas, this study measures the subjectivity -opinions, attitudes, and values-of professional from these two areas. Identifing the schemata(structure of subjectivity) would be a basic step for the strategies and construction of oriental nursing theory. The Q-sorts of 57 professionals were combined into five distinctive factors, namely, Q-types. The five factors were named as follows : Type I, Fundamentalist, consistently insists that the understanding of oriental medicine should be a basic step for the development of oriental nursing model, because ororiental medicine's theories and practices in curing are very unique and different from the western. Type Ⅱ, Pessimist, denies the uniqueness of oriental nursing field and its independency, because of lack of scientific evidences and professionalism. Type Ⅲ, Harmonist, believes the basic concepts in two different medic관 spheres are identical, but, at the same time, accept the uniqueness of the two. They try to propose Korean Nursing Model which accomodates local culture and conventions, and the way of Nurturing Life(Yang-sang), based on the traditional western nursing. Type W. Needy Follower, merely expects the Korean Nursing Model which considers the characteristics of Koreas culture and physical constitution and, thus, is more suitable to them. Some-times, they experience the discontent and conflict when they need more qualitative and culture-oriented nursing interventions. Type V, Alternative Giver, actully clarifies the concept of Oriental Nursing, and provides specific program as a alternative of universal western nursing. Various ways of Nurturing Life (mental, life, and diet Yang-sang) were introduced as a guideline for the specification of the nursing area and its con-tent. Throughout the study, the five different Q-factors were identified, and the concept of Oriental Nursing and aspects of its theory construetion were discussed.

• 한국건축시공학회지
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• 제21권3호
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• pp.249-256
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• 2021

건축공사 재해 중 거푸집공사 비중이 매우 크다. 거푸집 공사 재해 예방을 위해 관련 연구가 장기간 걸쳐 진행되고 있지만 지속적인 노력에도 불구하고 재해가 줄지 않고 있다. 따라서 본 연구에서는 AHP 기법을 활용하여 거푸집 붕괴사고 요인별 중요도 분석을 하고 관리할 우선 요소를 정하고자 한다. 분석 결과 시공요인, 관리요인, 설계요인 순으로 가중치가 높게 나타났다. 따라서 시공요인을 우선적으로 관리하면 거푸집 붕괴 재해를 예방할 수 있을 것으로 사료된다.

• 대한소아치과학회지
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• 제36권3호
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• pp.348-357
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• 2009

본 연구는 유구치 상아질의 각기 다른 부위(표층부, 심층부, 치경부)에서 복합레진 접착제의 접착강도를 비교, 평가하기 위하여 임상에서 흔히 사용하고 있는 서로 다른 4종의 접착방식(3-step total etch: 1군, 2-step total etch: 2군, 2-step self-etch: 3군, all-in-one: 4군)을 적용하고 복합 레진 ($Light-Core^{TM}$ Core Build-Up Composite)을 적층한 후, 미세인장접착강도를 비교하였을 때 다음과 같은 결과를 얻었다. 1. 접착방식간의 비교에서 레진의 접착방식에 따른 상아질 각 부위에서의 미세인장접착강도는 제 1군이 표층부에서 뚜렷이 높았으나(p<0.05) 2, 3, 4군은 부위에 따른 차이가 없었다. 2. 부위별 미세인장접착강도를 비교하여 보았을 때 상아질 표층부에서의 미세인장접착강도는 레진의 접착 방식간에 차이가 없었으나, 심층부에서는 2군, 3군, 4군 및 1군의 순으로 나타났고(p<0.05), 치경부에서는 2군과 3군이 1군과 4군에 비하여 현저히 높았다(p<0.05).

• 구강회복응용과학지
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• 제23권4호
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• pp.283-292
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• 2007

Two-step or one-step bonding systems generally inhibit curing process of dual-cured core build-up resin composite for their adhesive acidity. In addition this dual-cured core build-up resin composite can be applied to dentin of pulp chamber and root at the time that complete the endodontic treatment. The purpose of this investigation was to determine the influence of sodium hypochlorite on rnicrotensile bond strength of dual-cured core build-up resin composite. Extracted human molars were horizontally sectioned with 1mm thickness using low speed diamond saw. After the sectioned specimens were divided into 8 groups, adhesive systems (Clearfil SE-Bond, Prime&Bond NT[2-step, 1-step], Adper Prompt L-Pop) were then applied with or without sodium hypochlorite pretreatment. The treated specimen was filled with dual-cured core build-up resin composite (Luxacore, DMG corp., German). Then light cured for 40 seconds and soaked in $37^{\circ}C$ water bath for 24 hours. After the treated specimen was grinded with 1mm width and measured rnicrotensile bond strength by testing machine. Additionally 8 teeth were prepared for SEM evaluation. The results were as follows. : NaOCl treated groups generally had lower rnicrotensile bond strength but did not show any difference statistically except Adper Prompt L-Pop. When the teeth were treated by NaOCl, though the difference of applied adhesive system, it had no statistically significant difference within the NaOCl treated groups except the relation of between ClearFil SE-Bond adhesive system and Adper Prompt L-Pop adhesive system. In the SEM evaluation, NaOCl treated groups presented relatively long resin tags and incomplete hybrid layer formation generally.

• 대한치과보철학회지
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• 제46권4호
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• pp.372-380
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• 2008

연구목적: 본 연구의 목적은 즉시 상아질 봉쇄 (immediate dentin sealing; IDS)을 시행한 경우와 지연 상아질 봉쇄 (delayed dentin sealing ; DDS)를 시행한 경우를 비교하고, 지연 상아질 봉쇄 시 상아질 접착제를 먼저 중합한 경우와 복합레진과 함께 중합한 경우에 있어서 상아질과 복합레진의 결합강도를 비교하는 것이다. 재료 및 방법: 사람의 건전한 대구치 20개의 치관부를 삭제하여 상아질 표면을 노출시켰다. 상아질 접착 후 바로 복합레진을 축조하는 과정에서 군을 4 가지로 나누었다. 대조군은 주수 하에 model trimmer를 이용하여 치관부 삭제 후 바로 2-step etch-and-rinse dentin bonding agent (ONE-STEP, Bisco, USA)를 이용하여 상아질 접착을 시행하고 복합레진 (RENEW, Bisco, USA)을 수복하였다. 실험군 A는 치아 삭제 후, Fermit을 이용한 임시수복 상태로 5일간 생리식염수에 보관하였다. 임시수복 제거 후 상아질 접착제를 도포하고 별도의 중합없이 레진을 축조하고 함께 중합하였다. 실험군 B는 치아 삭제 후, 상아질 접착제 도포 및 중합하고 임시수복을 시행하여 5일간 생리식염수에 보관하였다. 임시수복 제거 후 상아질 접착제를 도포하고 별도의 중합없이 레진을 축조하고 함께 중합하였다. 실험군 C는 치아 삭제 후, 임시수복 상태로 5일간 생리식염수에 보관하였다. 임시수복 제거 후, 상아질 접착제를 도포 및 중합하고, 레진을 축조 및 중합하였다. 각 치아를 단면적 1 $mm^2$, 길이 10-12 mm의 막대형 시편으로 절단하여, 미세인장 결합강도를 측정하였다. 측정된 결합강도는 one-way ANOVA를 이용하여 비교 분석하였으며, 사후 검증은 Scheffe test를 이용하여 분석하였다. 연구결과: 본 실험의 결과는 다음과 같다. 1. 치아 삭제 후 별도의 상아질 접착 시행 없이 임시수복하고, 레진 축조 전 상아질 접착을 도포 후 별도의 중합과정 없이 레진과 함께 중합할 경우, 상아질과의 미세인장 결합강도는 유의하게 낮은 값을 보였다 (P < .01). 2. 치아 삭제 및 임시 수복 기간 후, 상아질 접착제를 먼저 중합하고 복합 레진을 수복하는 경우와 치아 삭제 후 상아질 접착을 시행하고 수복물 장착 시 상아질 접착을 재시행하는 경우 간의 상아질에 대한 결합강도의 차이는 없었다 (P > .05).

• Geomechanics and Engineering
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• 제12권5호
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• pp.739-752
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• 2017

This study was intended to evaluate the improved strength of the ground by applying the bio grouting method to a loose sandy ground. The injection material was prepared in the form of cement-like powder, with the bio injection material produced by microbial reactions. The grouting test was conducted under the conditions similar to the field where the bio injection material can be applied. In addition, the injection materials (cement and sodium silicate No. 3) used for Labile Waterglass (LW) method and the conventional grouting methodwere prepared through a two-solution one-step process. The injection into the specimens was done at a pressure of 150 kPa and then, with a bender element, their moduliof elasticity were measured on the 7th, 14th, 21st and 28th curingdays to analyze their strengths according to the duration of curing. It was confirmed that in all injection materials the moduli of elasticity increased over time. In particular, when 30% of the bio injection material was added to 100% cement, the modulus of elasticity tended to increase by about 15%. This confirmed that the applicability became higher when the bio injection material was used in place of the conventional sodium silicate.

• Restorative Dentistry and Endodontics
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• 제29권5호
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• pp.423-429
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• 2004

The purpose of this study was to evaluate the effect of multiple application of all-in-one dentin adhesive system on microtensile bond strength using confocal laser scanning microscope and microtensile bond strength test. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. In group I, Scotchbond Multipurpose (SM) was applied by manufacturer's recommendation. In group II, after Adper Prompt L-Pop was applied for 15s and light cured for 10s. the second coat was re-applied and light-cured. In group III, after light-curing the second layer. the third coat was re-applied and light-cured. Specimens bonded with a resin-composite were sectioned into resin-dentin stick for measuring the adhesive layer thickness by confocal laser scanning microscope and evaluating micro-tensile bond strength. The adhesive layers of three-step dentin adhesive system. 3 coats of Adper Prompt L-Pop had significantly thicker than SM. 2 coats of Adper Prompt L-Pop (p < 0.05). However. there was no significant differences in bond strengths between SM and 3 coats of Adper Prompt L-Pop (p > 0.05). And SM. 3 coats of Adper Prompt L-Pop had significantly higher than 2 coats of Adper Prompt L-Pop in bond strengths (p < 0.05).