드래그 피니싱 공정 기반 폴리싱 연마제를 이용한 초경 드릴 및 서멧 리머 공구의 가공 평가

하정호(Jeong-Ho Ha),사민우(Min-Woo Sa) 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.2

After drilling, reaming is required to process a workpiece for obtaining an excellent surface quality. In general, a cermet is defined as a “composite of a ceramic hard phase and metal-bonded phase.” Cermets have excellent abrasion resistance, thermal resistance, and performance in finishing operations that require surface roughness and processing precision. However, although cermets have significant advantages, research on them is insufficient. In this study, workpiece SM45C was machined using drills and cermet reamers. The cermet reamer was processed for drag finishing for 0, 4, and 6 min. The experimental results showed the effects of drag finishing on surface roughness and dimensional accuracy.

자유 형상 제작 기술 기반의 세라믹 제작 시스템을 이용한 3차원 인공지지체 제작에 관한 연구

사민우 ( Min Woo Sa ),김종영 ( Jong Young Kim ) 한국조직공학·재생의학회 2013 조직공학과 재생의학 Vol.10 No.2s

Solid free-form fabrication (SFF) technology has a great advantage in applying to porous scaffolds fabrication with the desired inner/outer architectures for tissue regeneration applications. In this study, a ceramic fabrication system based on deposition/heating devices was developed to fabricate the porous calcium phosphate scaffold. Calcium phosphate ceramics have been used extensively as scaffolding materials to regenerate new tissue or the ingrowth of tissue. 3D porous β-tricalcium phosphate (β-TCP) scaffolds were fabricated to investigate the effect of scaffolds for bone tissue engineering. The phase content, mechanical properties, and porous structure of the ceramic scaffolds were characterized. The results showed that ceramic scaffolds with a deposition width of 600 μm and pore size of 400 μm were fabricated using bio-ceramic fabrication system. The compressive strength and modulus of the α/β-TCP scaffold sintered at 1300oC for 2 h are about 1.91 and 131MPa, respectively. Those results suggest that ceramic scaffolds may the basic requirements for bone tissue engineering.

듀얼헤드 적층 기술을 이용한 나노섬유로 결합된 3D 인공지지체 제작

사민우(Min-Woo Sa),이창희(Chang-Hee Lee),김종영(Jong Young Kim) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.1

In bone tissue engineering, polycaprolactone (PCL) is one of the most widely used biomaterials to manufacture scaffolds as a synthetic polymer with biodegradability and biocompatibility. The polymer deposition system (PDS) with four axis heads, which can dispense bio-polymers, has been used in scaffold fabrication for tissue engineering applications. A dual-head deposition technology of PDS is an effective technique to fabricate 3D scaffolds. The electrospinning technology has been widely used to fabricate porous and highly interconnected polymer fibers. Thus, PDS can fabricate nanofiber-combined hybrid scaffolds using fused deposition modeling (FDM) and electrospinning methods. This study aims to fabricate nanofiber-combined scaffolds with uniform nanofibers using PDS. The PCL nanofibers were fabricated and evaluated according to the fabrication process parameters. PCL nanofibers were successfully fabricated when the applied voltage, tip-to-collector distance, flow rate, and solution concentration were 5 ㎸, 1 ㎝, 0.1 ml/h, and 8 wt%, respectively. The cell proliferation was evaluated according to the electrospinning time. Scanning electron microscopy was used to acquire images of the cross-sectioned hybrid scaffolds. The cell proliferation test of the PCL and nanofiber-combined hybrid scaffolds was performed using a CCK-8 assay according to the electrospinning time. The result of in-vitro cell proliferation using osteosarcoma MG-63 cells shows that the hybrid scaffold has good potential for bone regeneration.

골 조직 재생을 위한 복합 공극 패턴을 가진 ZrO₂/BCP/PCL 인공지지체의 실험적 평가

사민우,심해리,김종영,Sa, Min-Woo,Shim, Hae-Ri,Kim, Jong Young 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.11

최근 조직 공학 분야에서는 폴리카프로락톤(PCL), 수산화인회석, 삼인산칼슘, 이상인산칼슘(BCP), 지르코니아(Zirconia, $ZrO_2$) 와 같은 합성 생체폴리머와 생체세라믹 등은 다양한 생체 조직 또는 장기를 재생하는데 필요한 대체재로 사용되고 있다. 따라서, 본 연구의 목적은 골 조직 재생을 위한 혼합된 $ZrO_2$/BCP/PCL(ZBP) 인공지지체의 특성을 관찰하기 위함이다. 단선 패터닝 실험의 결과를 토대로 내부연결성 있는 공극을 가지고 $45^{\circ}+135^{\circ}$ 타입과 격자타입의 새로운 복합 공극 패턴을 가지는 혼합된 ZBP 인공지지체는 폴리머 적층시스템에 의해 성공적으로 제작되었다. 뿐만 아니라 기계적 특성에 대한 ZBP 인공지지체의 효과를 분석하였다. 게다가 MG63 세포에 대한 ZBP 인공지지체의 세포 상호작용은 CCK-8 분석을 이용함으로써 평가되었다. Recently, synthetic biopolymers and bioceramics such as poly (${\varepsilon}$-caprolactone)(PCL), hydroxyapatite, tricalcium phosphate, biphasic calcium phosphate(BCP), and zirconia have been used as substrates to generate various tissues or organs in tissue engineering. Thus, the purpose of this study was the characterization of $ZrO_2$/BCP/PCL(ZBP) scaffold for bone tissue regeneration. Based on the result of single-line test, blended 3D ZBP scaffolds with fully interconnected pores and new complex pore pattern of $45^{\circ}+135^{\circ}$-type and staggered-type were successfully fabricated using a polymer deposition system. Furthermore, the effect of ZBP scaffold on mechanical property was analyzed. In addition, in vitro cell interaction of ZBP scaffold on MG63 cells was evaluated using a cell counting kit-8(CCK-8) assay.

치과 치료용 초음파 스케일러의 성능 및 안정성에 대한 실험 평가

사민우(Min-Woo Sa),고태조(Tae-Jo Ko),전금상(Geum-sang Jeon),이종민(Jong-Min Lee),김종영(Jong Young Kim) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.1

치과 분야에서 초음파를 이용한 수술기 및 스케일러의 사용은 꾸준하게 증가하고 있다. 이때 개발된 기기의 성능 및 안정성은 시술 받는 환자에게 결정적인 요소로 작용하기 때문에 상업화 전에 반드시 시험 평가되어야 한다. 그래서 골 절단 및 치아 스케일링 평가를 수행할 수 있는 핸드피스 이송 시스템을 자체 개발하여 사용하였다. 본 연구의 목표는 초음파 스케일러 팁을 이용하여 치아 손상 정도를 평가하기 위함이다. 추가적으로 초음파 기기의 열 발생 및 소음에 대한 측정을 수행해보았다. 결과적으로 Ultrasonic NX 기기의 높은 출력은 실험을 통한 치아에 심각한 손상을 입힐 수 있지만 열 화상 카메라를 이용한 열 발생 및 소음 측정을 통해 안정적인 범위에 있었다. The use of ultrasonic surgery units and scalers are steadily increasing in the field of dentistry. Such units and scalers should be evaluated before they are commercialized because the mechanical performance and stability of equipment is crucial for patients. Hence, we created a hand-piece moving system that can test bone cutting and teeth scaling. The purpose of this study was to evaluate the teeth scaling performance of ultrasonic scaler unit. Additionally, we measured the temperature distribution and noise during the test. through an experimental test, we found that a high output of an Ultrasonic NX device can cause serious damage to the teeth surface, and it was not within range in heat generation distribution and noise test.

골 절삭용 초음파 수술기의 실험적 평가에 관한 연구

사민우(Min-Woo Sa),심해리(Hae-Ri Shim),고태조(Tae-Jo Ko),이종민(Jong-Min Lee),김종영(Jong Young Kim) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.1

In the dentistry field, an ultrasonic surgery unit is widely used in bone cutting and scaling to reduce operation time and minimize hemorrhage. The purpose of this study was to evaluate bone cutting and the effect of a specimen’s temperature on the two-type ultrasonic surgery unit using a handpiece moving system(HMS). A HMS, which can cut the bone, was developed to perform the experimental procedure with precision of motion control. Bone specimens were prepared from a combination of epoxy-hardener and cortical bone of bovine leg. Through the bone-cutting experiment, the cutting depth was evaluated by not only scanning electron microscopy, but also Vernier calipers. Also, the temperature distribution was measured by a thermo-graphic camera. This study may be applied methodically in various experimental evaluations on a performance test by a HMS.

골 재생용 인공지지체 제작 및 평가를 위한 나노-마이크로 적층 시스템의 적용

사민우(Min-Woo Sa),하성우(Seong-Woo Ha),김종영(Jong Young Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11

The purpose of this study was to fabricate and evaluate various scaffolds for bone regeneration using nano-micro deposition system based on the solid free-form fabrication (SFF) technique. Nano-micro deposition system was designed to use electrospinning and fused deposition modeling (FDM). Nano-based PCL and pure β-TCP scaffolds were fabricated by nano-micro deposition system. Structure and morphology of the fabricated scaffolds were analyzed by a scanning electron microscopy (SEM). The compressive strength of the fabricated scaffolds was evaluated by calculating a slop of each stress-strain curves. The in vitro cell experiment was also carried out, in order to evaluate the cell proliferation of the fabricated scaffolds. We showed that nano-based PCL and pure β-TCP scaffolds would be a promising substrate to regenerate defected bone tissues.

Development of a Cemented Carbide-Welded Deburring Tool for Burr Removal in Drill Holes of AL6061 Workpieces

Min-Woo Sa(사민우),Jae-Won Lee(이재원) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.5

In recent years, automated process technology has allowed for the rapid manufacturing of metal parts. Maintaining high product quality is of vital importance during the production of these parts. Surface defects occurring after processing can compromise their assembly precision and performance. In this study, a deburring tool was developed that can remove burrs generated from drilling. Through the evaluation of processing, burrs were completely removed at entrance and exit surfaces. Therefore, this newly developed deburring tool shows better performance than deburring tools currently in use.

A Study on Temperature Changes during Bone Scaling and Cutting of Dental Ultrasonic Scaling/Surgery System

Min-Woo Sa(사민우),Tae-Jo Ko(고태조),Jong Young Kim(김종영) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.2

While dental clinics still use the ultrasonic scaling/surgery tool for teeth scaling and cleaning the tool’s use is expanding steadily to include treatment of damaged teeth and bone tissue. In this study, a handpiece moving system (HMS) was developed to evaluate bone scaling and cutting in the field of dentistry. The HMS, through a scaling test of bone using a scaler tip, it was able to identify surface damage. Additionally, a thermos-graphic camera was used to observe the temperature distribution that occurred during the bone scaling and cutting process. Consequently, we found that increasing the working load increased the amount of surface damage. Changes in temperature distribution occurred slowly and were maintained within safety bounds for 10 minutes. Going forward, we will compare the HMS performance on scaling and cutting with other devices.

Development of a Drill Tool for CFRP Machining and Evaluation of Drilling Processing

Min-Woo Sa(사민우) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.3

Carbon fiber-reinforced plastics (CFRPs) are extremely strong and light fiber-reinforced plastics containing carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and rigidity are required, such as in the aerospace, automotive, and ship superstructure industries. In CFRP drilling, the tool performance greatly varies depending on the tool shapes, cutting conditions, and diamond coating. This study developed a new type of tungsten carbide drill with multi-blade edges to evaluate the surface quality of CFRP materials according to the coating thickness of diamond-coated drills. Experiments on tool wear, surface roughness, and burr formation were conducted. The bore exit quality of a 12 μm-coated drill was better than that of a 6 μm-coated drill. The superior effects of the 12 μm-coated drill and the good surface quality of CFRP were also demonstrated.