• 문화기술의 융합
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• 제9권5호
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• pp.529-534
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• 2023

고속 및 대면적 인쇄를 위한 라인 프린팅 기술은 늘어난 헤드 길이만큼 헤드 내부로 잉크를 공급하는 유로를 확보해야 하는 구조적 취약점과 제조 과정에서 발생하는 잔류응력에 의한 피드홀 변형으로 인해 노즐층이 파손되거나 잉크가 누출되는 결함이 있다. 따라서 본 논문에서는 견고하고 신뢰할 수 있으며 라인 프린팅 방식에 보다 적합한 열전사 방식의 잉크젯 프린트 헤드 형상을 제안하고자 한다. 먼저 실험을 통해 초기 라인 프린팅 헤드의 변형량을 측정한 후 이를 등가의 하중량으로 변환하였으며 FEA 해석을 통해 하중 추정 방법의 타당성을 검증하였다. 또한 헤드 크기를 증가시키지 않으면서 변형을 최소화할 수 있도록 기둥이나 지지벽으로 단위 노즐을 보강하거나 지지빔이나 건/습식각된 브릿지를 추가하여 내부 강성을 증가시킨 헤드 구조를 설계하였으며, 피드홀 변형이 최대 90% 감소하는 것을 확인하였다. 제안된 형상 중 공정 편의성과 제작비용을 고려하여 건식각된 피드홀 브릿지 형태의 헤드를 선정하였으며 실제 제작을 통해 노즐층 변형이나 잉크 누출 없이 정상 작동하는 것을 확인하였다.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.213-222
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• 1998

Advisor: Prof. The quality of apical seal obtained with 3 different gutta-percha obturation techniques was compared in 49 recently extracted single rooted teeth. The root canals were instrumented using step-back technique and obturated with laterally condensed gutta-percha, Continuous Wave gutta-percha, and hybrid technique. Teeth were suspended in black India ink for 7 days, cleared, and then examined under a stereomicroscope at ${\times}10$ magnification. The results were as follows; 1. All experimental groups produced favorable apical seal. 2. The mean leakage was $0.23{\pm}0.25mm$ for group 1, $0.17{\pm}0.21mm$ for group 2, and $0.19{\pm}0.23mm$ for froup 3, but there was no statistical difference amoung them. Within the limits of the results of this experiment, the Continuous Wave gutta-percha obturation technique demonstrated relatively favorable apical sealing effect and shorter obturation time. Thus, it is thought that this obturation technique is a acceptable method for clinical use but further studies on this metter should be conducted.

• Restorative Dentistry and Endodontics
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• 제23권2호
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• pp.561-574
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• 1998

본 연구는 근관형성시 생성되는 도말층의 존재가 System-B를 이용한 가온 수직가압충전 후의 미세누출에 미치는 영향을 관찰하고자 시행되었다. 최근에 발거된 20개의 상악전치를 이용하여 Ni-Ti 전동화일의 한 종류인 Quantec series 2000$^{TM}$(Tycom, USA) 과 수통 K-화일로 근관형성시 생성되는 도말층의 차이와 EDTA 용액 및 EDTA/차아염소산나트륨 용액의 2종 세척액에 따른 도말층의 제거양상을 주사전자현미경으로 관찰하였다. 44개의 상악전치를 이용하여 System-B를 이용한 가온 수직가압충전후의 미세누출의 정도를 근관형성시 생성되는 도말층의 존재유무에 따라 색소침투법과 치아투명화법을 이용하여 비교한 결과 다음과 같다. ${\cdot}$ 수동 K-화일이나 전동 Ni-Ti 화일로 근관형성한 군 모두에서 EDTA 용액을 사용한 군은 도말층이 완전히 제거되어 상아세관이 깨끗하게 개방되었지만, 차아염소산나트륨 용액만 사용한 군은 근관의 대부분이 도말층으로 덮혀 있었고 개방된 상아세관은 발견할 수 없었다. ${\cdot}$ 수동 K-화일 군과 전동 Ni-Ti 화일 군 사이에는 생성된 도말층의 차이를 관찰할 수 없었다. ${\cdot}$ EDTA 용액을 이용하여 도말층을 제거한 경우와 차아염소산나트륨 용액만을 사용한 경우간의 비교에서는, sealer를 사용했을 때에는 도말층을 제거한 경우가 유의하게 적은 색소 침투를 나타냈으며(p<0.01), sealer를 사용하지 않았을 때에는 EDTA 용액과 차아염소산나트륨 용액으로 세척한 경우가 다소 적은 색소 침투를 나타냈으나 통계적 유의성은 없었다(p>0.05). ${\cdot}$ EDTA 용액를 이용하여 도말층을 제거한 후 sealer사용 유무에 따른 비교에서는 sealer를 사용한 경우에서 통계적으로 유의하게 적은 색소침투를 나타냈다(p<0.01). ${\cdot}$ EDTA 용액을 사용하지 않고 차아염소산나트륨 용액만으로 근관형성한 후 sealer사용 유무에 따른 비교에서는 sealer를 사용한 경우에서 통계적으로 유의하게 적은 색소 침투를 보였다(p<0.01).

• 사물인터넷융복합논문지
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• 제6권1호
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• pp.97-102
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• 2020

사물인터넷 환경에서 다중 객체의 스위치 제어는 고전압을 구동하기 위해 레벨 시프터가 있는 여러 솔리드 스테이트 구조로써 낮은 ON 저항과 양방향 릴레이 MOS 스위치를 통합했으며 외부 직렬 논리 제어에 의해 독립적으로 제어되어야 한다. 이 장치는 의료용 초음파 이미지 시스템, 잉크젯 프린터 제어 등의 IoT 기기뿐만 아니라, 켈빈 4 단자 측정을 사용한 PCB 개방 / 단락 및 누출 테스트 시스템과 같은 저전압 제어 신호에 의한 고전압 스위칭 제어가 필요한 응용 제품에 사용하도록 설계되었다. 이 논문에서는 FPGA (Field Programmable Gate Array) 테스트 패턴 생성을 사용한 아날로그 스위치 제어 블록의 구현 및 검증에 대하여 고찰하였다. 각 블록은 Verilog 하드웨어 설명 언어를 사용하여 구현된 후 Modelsim에 의해 시뮬레이션 되고 FPGA 보드에서 프로토타입화 되어 적용되었다. 제안된 아키텍처는 IoT 환경에서 여러개의 개체들을 동시에 제어하여야 하는 분야에 적용할 수 있으며 유사 형태의 IC를 테스트하기 위해 제안된 패턴 생성 방법을 적용할 수 있다.

• Archives of Plastic Surgery
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• 제35권5호
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• pp.626-629
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• 2008

Purpose: We investigate the possibility of vessel preservation with glycerol and evaluate the potential of preserved gastroepiploic artery as a tool for the microsurgical practice. Methods: In 5 early gastric cancer patients, IRB(No. C-0603-040-170), we gained gastroepiploic artery specimens(5 segments, about 10 cm) after gastrectomy. Each segment was rinsed in a normal saline and subsequently placed in a bottle, containing 50 mL anhydrous glycerol (87%). The bottles were refrigerated at $4^{\circ}C$, the longest preservation time being 5 months. Results: At first glance, no fragmentation was detected and the surface of vessel seemed mild sclerotic. In histological examination, vascular structures remained intact though preservation with glycerol led to a mild atrophy of the smooth muscle in the tunica media. Especially, we found out the elastic fibers and endothelial lining of the intima were preserved until 5 months. Adequate status for using microsurgical practice was also maintained and leakage test was performed successfully with gentian violet ink. Conclusion: Based on the results obtained in this study, the gastroepiploic artery preservation with glycerol as a training model for microvascular anastomosis is a technically very simple procedure and useful for the novice microsurgeon.

• Restorative Dentistry and Endodontics
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• 제24권3호
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• pp.482-489
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• 1999

The purpose of this study was to compare sealing ability between lateral condensation and continuous wave of condensation in depend of root canal curvature. In this study, we divided fifty-six human molar teeth into two group in depend of Schneider method, and then subdivided them into four experimental group (each group is composed of twelve teeth) by canal curvature and obturation method, and eight teeth were served as positive and negative controls. Specimens were prepared by Quantac 2000 series file and obturated by lateral condensation or System B. Specimens were immersed in india ink for 7 days, decalcified by 10% nitric acid, dehydrated by 75, 95 and 100% alcohol in order, cleared by methyl salicylate and then measured of dye penetration with stereomicroscope(${\times}6.5$ magnification) and Image Pro plus. The data were analyzed stastically by one-way ANOVA and Scheffe test. The data were as follows: 1. The mean leakage was $0.725{\pm}1.167$ for group A, $0.813{\pm}0.921$ for group B, $0.809{\pm}0.997$ for group C, $1.111{\pm}1.147$ for group D, but no significant difference among them(p>0.05). 2. Lateral condensation had better sealing ability than continuous wave of condensation, but no significant difference among them(p>0.05). 3. There was no significant difference between root canal curvature degree and microleakage(p>0.05).

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.236-246
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• 1998

The purpose of this study was to compare the degree of micro- leakage of new glass ionomer root canal sealer, Ketac-Endo(ESPE Co., Seefeld, Germany) with that of AH-26(De Trey Co., Ltd., U.S.A.). Root canal treatment using K -file, H -file, Gate Glidden drill was conducted on 49 extracted single-rooted teeth. 45 teeth were randomly divided into 3 experimental groups(15 teeth per group) and 4 teeth were used as the control group. Group 1 was used AH -26 sealer with the lateral condensation method for canal filling, group 2 was used Ketac-Endo with the single cone method and group 3 was used Ketac-Endo with the lateral condensation method. The control group was obturated with the single cone method without sealer. The teeth were covered with two coats of nail varnish after 48 hours of obturation. The teeth were immersed in India ink for 1 week and cleaned with methyl salicylate and then the degree of dye penetration were measured with stereomicroscope. The data were analyzed statistically by one-way ANOVA. The results were as follows: 1. 7 teeth in group 1, 5 in group 2, and 3 in group 3, were showed evidence of microleakage implying appropriate canal filling. 2, The mean average of microleakage was $0.17{\pm}0.32mm$ in group 1, $0.30{\pm}0.37mm$ in group 2. $0.10{\pm}0.21mm$ in group 3, showing that canal filling using the lateral condensation canal filling method with Ketac-Endo showed the least microleakage and using the single cone method with Ketac-Endo showed the largest amount of microleakage, 3. There were no statistically significant difference in the variation of microleakage among groups. From the results above, Ketac-Endo which has the advantage of glass ionomer, whether using the single cone method or the lateral condensation method, showed similar results as AH-26, but for clinical application it is thought that were studies on the properties of Ketac-Endo should be followed.

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.628-634
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• 1996

The purpose of this study was to investigate the effect of moisture on apical sealing properties of root canal. Fifty five single rooted human teeth were selected from maxillary and mandibular teeth. After removing crown portion at the cemento-enamel junction, all teeth were routinely prepared with step-back method. And then, the canals were dried with paper point and the teeth were randomly divided into 3 groups of 15 teeth each, and remaining 10 teeth were used as positive and negative control teeth : Group 1 were irrigated with 1ml of 95% alcohol and dried with air and paper point. Group 2 and 3 were intentionally contaminated with 0.05ml of 3.5% NaOCl or saliva, respectively. All the teeth were obturated with sealapex and gutta percha cone by lateral condensation technique, and covered with two coat of nail varnish after 48 hours of obturation. The teeth were immersed in india ink for 1 week and cleaned with methyl salicylate and then the degree of dye penetration were measured with stereomicroscope. The data were analyzed statistically by one-way ANOVA. The results were as follows : 1. All experimental groups showed varying degrees of dye penetration, and the mean degree of dye penetration was 0.1mm to 0.7mm. 2. Saliva contamination group(group 3) showed the highest amount of dye penetration, followed by NaOCl contamination group, then alcohol dried group, but there was no significant difference among three experimental groups. * This results suggest that there was no significant differences of apical leakage after canal obturation between alcohol dried canal and moisture present canals and the use of alcohol instead of paper point is unnecessary to dry the canals prior to canal filling. But other factors such as bacterial contamination and sealer discoloration by moisture must be considered in application of this results to clinical practice.

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.517-529
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• 1996

The purpose of this study was to evaluate the apical sealing ability of the Thermafil endodontic obturation technique and to compare it with lateral condensation technique. 42 straight canals from extracted human anterior teeth and 42 curved canals(> $25^{\circ}$) from maxillary and mandibular molar teeth were selected. And 80 of them were divided into four groups, 20 canals respectively. The teeth in prior two groups had straight canals and the other two groups had curved canals. The rest of four canals served as positive and negative controls. After resecting anatomical crowns, all canals were prepared using a standard step-back technique. Lateral condensation was used to obturate two groups, one group of straight ones the other curved. And Thermafil obturators were also used in the same two groups. Obturated teeth were infiltrated by India ink for a week, decalcified and cleared with 5% nitric acid and methyl salicylate. The apical leakage and the frequency of filled lateral and accessory canals were measured with stereomicroscope and also apical extrusion of sealer and gutta-percha and obturation time were checked and the data were analyzed statistically(one-way ANOVA, t-test, Chi-square test). The results were as follows : 1. There was no significant difference in the degree of dye penetration between Thermafil and lateral condensation groups(p>0.05). 2. Apical extrusion of sealer and gutta-percha occurred significantly more often with Thermafil obturators in straight canals(p<0.05), but not significantly different in curved canals(p>0.05). 3. Canal obturation time with Thermafil obturators was significantly faster than lateral condensation (p<0.05). 4. The Thermafil groups showed a higher frequency of filled lateral and accessory canals than in the lateral condensation groups. But the difference was not statistically significant (p>0.05).

• Restorative Dentistry and Endodontics
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• 제33권1호
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• pp.66-75
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• 2008

본 연구에서는 근관형성의 치근단 크기가 근관 충전의 치근단 폐쇄에 미치는 영향에 대해 알아보고자 하였다. 36개의 단근관, 단근치를 대상으로 3가지 치근단 크기 (Master apical file : #25, #40, #60)에 따라 3가지 실험군으로 나누어 $Profile^{(R)}$과 $LightSpeed^{(R)}$를 이용하여 근관을 확대하고, Modified continuous wave technique으로 근관충전을 시행하였다. 미세누출의 측정을 위해 실험군당 10개의 치아를 1주일간 India ink에 넣어 색소 침투를 일으키고 치아를 투명화시켜 미세누출의 정도를 측정하였다. 미세누출에 치근단 크기가 미치는 영향을 분석하기 위하여 Kruskal-Wallis one-way ANOVA를 시행하였고, 사후 검정을 위하여 Student-Newman-Keuls method를 시행하였다. 또한, 치아 단면의 형태를 관찰하기 위하여 색소 침투까지 실행된 각 실험군당 2개의 치아를 근첨 1 mm에서 4 mm까지 1 mm간격으로 수평 절단하고 사진 촬영하였다. 각 실험군에서 측정된 미세누출양을 Krustal-Wallis one-way ANOVA에서 분석한 결과 치근단 크기는 유의성 있게 (P < 0.05) 미세누출에 영향을 미쳤으며 치근단 크기가 클수록 미세누출의 평균간과 표준편차 값은 감소하는 경향을 보였다. Student-Newman-Keuls method를 통한 사후 검정에서 치근단 크기가 #25 - #40, #25 - #60에서 유의 한 차이를 보였으며 #40 - #60간에는 통계적인 유의차는 없었다. 단면형태에서는 대부분의 치아에서 난원형의 근관 형태를 관찰 할 수 있었고, 치근단의 크기가 작을수록 성형된 근관에 불규칙한 내면이 존재하였고 gutta-percha나 sealer로 충전되지 않는 recess의 면적이 증가함을 알 수 있었으며 이러한 recess는 미세누출의 통로가 됨을 확인 할 수 있었다. 본 연구 결과, Modified continuous wave technique으로 근관충전시 근관 형성된 치근단 크기가 커질수록 보다 일관되고 성공적 인 결과를 예상할 수 있는 근관충전을 시행할 수 있음을 알 수 있었다.