• The Journal of Engineering Geology
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• v.31 no.4
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• pp.561-577
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• 2021

The ten standard roughness profiles suggested by Barton and Choubey (1977) were extended to make three-dimensional (3D) joint models whose profiles were identical at any cross section. Replicas of joint models were produced using plaster of Paris, and direct shear tests were performed to verify the joint roughness coefficients (JRC) of the standard roughness profiles. Joint shear strengths measured by direct shear tests were compared with those predicted by the shear failure criterion suggested by Barton (1973) based on JRC, joint compressive strength (JCS), and joint basic friction angle (𝜙_b). Shear strengths measured from joints of the first and fourth standard roughness profiles were close to predicted values; however, shear strengths measured from the other joint models were lower than predicted, the differences increasing as the roughness of joints increased. Back calculated values for JRC, JCS, and from the results of the direct shear tests show measured shear strengths were lower than predicted shear strengths because of the JRC values. New JRC were back calculated from the measured shear strength and named JRC_m. Values of JRC_m were lower than the JRC for the standard roughness profiles but show a strong linear relationship to JRC. Corrected JRC_m values for the standard roughness profiles are provided and revised relationships between JRC_m and JRC, and new shear strength criterion are suggested.

• Applied Chemistry for Engineering
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• v.35 no.5
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• pp.423-428
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• 2024

Microneedles with micron-sized needle arrays are an emerging technology for the transdermal administration of active pharmaceutical ingredients with minimally invasive pain. Over the past decade, although various additive manufacturing technologies have been employed for precise fabrication of microneedles, these methods are often limited by material compatibility and bioavailability, in addition to being time-consuming and costly. In here, we compare the resolution of Polyjet and DLP-SLA 3D printing methods for the precise fabrication of biodegradable PCLDA/PEGDA microneedles. To enhance the structural accuracy of the microneedles from both printing methods, we evaluate the 3D printing conditions, including 3D printing angle and needle height and diameter. Molds for microneedles are fabricated using optimized 3D printing methods, and subsequent replica molding processes are employed to fabricate the polymeric microneedles with sharp need tips. Finally, we use photocurable PCLDA and PEGDA for biodegradable and biocompatible microneedles, and their mechanical properties as PCLDA concentrations are analyzed to assess the strength required for skin insertion. This study has demonstrated the efficient and low-cost fabrication of high-resolution microneedles for transdermal drug delivery.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.133-142
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• 2006

Many methods have been tried to more correctly measure rock joint roughness. However, true roughness may be distorted and underestimated due to the sampling interval and measurement method. Thus, currently used measurement methods produce a dead zone and distort roughness profiles. The purpose of this study is to suggest new roughness measurement method by a camera-type 3D scanner as an alternative of currently used methods. First, the underestimation of artificial roughness is analyzed by using the current measurement method such as laser profilometry. Second, we replicate eight specimens from two rock joint surfaces, and digitize by a 3D scanner. Then, the roughness coefficient values obtained from eight numbers of 3D surface data and from three hundred twenty numbers of 2D profiles data are analyzed by using current and new measurement methods. The artificial simulation confirms that the sampling interval is one of main factors for the distortion of roughness and shows that inclination of waviness may not be considered any current methods. The experimental results show that the camera-type 3D scanner produces 10% larger roughness values than current methods. As the proposed new method is a fast, high precision and more accurate method for the roughness measurement, it should be a promising technique in this area.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1299-1302
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• 2004

A real object duplication system (RODS), including three dimensional (3D) scanner and solid freeform fabrication system (SFFS), is a device to make three-dimensional objects directly from the drawing or photo data. A Selective Multi-Laser Sintering (SMLS) process designed in this paper is by which computer images received using 3D scanner are built up from polymer powder on building room of large size using dual laser at industrial type SFF system. Using the process can rapidly produce real object duplication components of industrial type such as cylinder, engine block, chassis of automobile, etc. In this paper, the industrial type SFF system using SMLS process is manufactured and the system is satisfied with high precision and high speed processing technique. To research characteristics of each part for theindustrial type SFF system, a structure and thermal analysis and test of each part is carried out. Also, to achievement of high performance for industrial type SFF system, design and fabrication for the structure, heater, nitrogen supply, laser and control part are carried out.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.15-19
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• 2001

A dedicated reverse engineering(RE) system for rapid manufacturing of human head in a 3D bust has been developed. The first step in the process is to capture the surface details of a human head and shoulder by three scanners based upon the digital moire fringe technique. Then the multiple scans captured from different angles are aligned and merged into a single polygonal mesh, and the aligned data set is refined by smoothing, subdividing or hole filling process. Finally, the refined data set is sent to a 4-axis computer numerically control(NC) machine to manufacture a replica. In this paper, we mainly describe on the algorithms and software for aligning multiple data sets. The method is based on the recently popular Iterative Closest Point(ICP) algorithm that aligns different polygonal meshes into one common coordinate system. The ICP algorithm finds the nearest positions on one scan to a collection of points on the other scan by minimizing the collective distance between different scans. We also integrate some heuristics into the ICP to enhance the aligning process. A typical example is presented to validate the system and further research work is also discussed.

• Cartoon and Animation Studies
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• s.26
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• pp.57-78
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• 2012

This article deals with the change of disney feature-length drawn animation since using digital technology. The spread of digital technology in the territory of traditional animation brought a massive transformation. Analogue production system for disney drawn animation was gradually replaced by digital production system and in the process, the overall quality of disney drawn animation was improved, although drawn animation industry had declined considerably due to the success of 3D computer animation. Currently, disney drawn animations not only just adopt digital technology but also use it for expressing the distinctive sensibility of the drawn animation.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.202-210
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• 2022

Recently with the advance in digital dentistry, the fabrication of dentures using computer-aided design and computer-aided manufacturing (CAD-CAM) is on the rise. The denture designed through a CAD software can be produced in a 3-dimensional manufacturing process. This process includes a subtractive processing method such as milling and an additive processing method such as 3D printing and in which it can be applied efficiently in more complex structures. In this case, complete dentures were fabricated using Stereolithography (SLA)-based 3D printing to shorten the production time and interval of visits in patient with physical disabilities due to cerebral infarction. For definitive impression, the existing interim denture was digitally replicated and used as an individual tray. The definitive impression obtained with polyvinyl siloxane impression material was including information about the inclination and length of the maxillary anterior teeth, vertical dimension, and centric relation. In addition, facial scan data with interim denture was obtained so that it can be used as a reference in determination of the occlusal plane and in arrangement of artificial teeth during laboratory work. Artificial teeth were arranged through a CAD program, and a gingival festooning was performed. The definitive dentures were printed by SLA-based 3D printer using a FDA-approved liquid photocurable resin. The denture showed adequate retention, support, and stability, and results were satisfied functionally and aesthetically.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.171-178
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• 2003

This study was conducted to investigate the effect of electric fusion methods on cell fusion rate and embryo development by somatic cell nuclear transfer in Korean Native Cattle. The KNC ear cell was cultured in vitro for confluence in serum starvation condition(DMEM＋0.05％ FBS) for cell confluence. The zona pellucida of IVM oocytes were partially dissection using micro pipette. Ear cells were transferred into an enucleated oocyte. The reconstructed embryos were electrically fused with Zimmermann Cell Fusion Medium(ZCFM). Nuclear transfer embryos were activated with a combination of 10${\mu}{\textrm}{m}$ calcium ionophore(5 min) and 2.0mM 6-DMAP(3 hr). The activated embryos were cultured in CR1 -aa medium contains 0.3％ BSA or 10％ FBS at 37$^{\circ}C$, 90％ $N_2$, and 5％ $CO_2$in incubator for 6 days. The fusion rates were 51.6％(chamber) and 68.9％(needle), respectively and there were significantly difference between the fusion method(P<0.05). But, lysis rates were not significantly different(10.7％, 11.5％), respectively. The cleavage rates were significantly different between the chamber method(73.2％) and needle method(80.3％), respectively(P<0.05). The rates of early embryos(2∼4cells) and blastocysts of chamber and needle methods were 54.1％, 61.1％ and 18.4％, 26.3％ respectively, and needle method was significantly higher than chamber method(P<0.05). But, morulae formation rate were not significantly differences between the chamber(6.7％) and needle(6.2) method(P <0.05). These result suggest that electric fusion of needle method was to be profitable for nuclear transfer embryo fusion rate, blastocyst formation rate and reduce of oocyte lysis.

• Journal of Technologic Dentistry
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• v.7 no.1
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• pp.27-31
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• 1985

From time to time, it is necessary to reconstruct the crown for the abutment tooth of the partial denture. It has been difficult and lack of accuracy in it's construction. I studied and discovered a new method of reconstructing the crown, that is rather easier and more accurate than being used, in the following points. 1) It is good in function and use of the partial denture ready made. 2) It is good to protect the periodental tissue and avoid the uneasy feeling. 3) It is so easy and accurate in the procedure of reconstruction. 4) And patient's charge would be less, because of not reconstructing the partial denture.

• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.767-782
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• 2006

이 연구의 목적은 DNA microarray 분석법을 이용하여 건강한 사람치주인대섬유모세포, 건강한 사람치은섬유모세포, 복제노화된 사람치은섬유모세포, 염증성 사람치주인대 섬유모 세포의 유전자 발현 형태를 상호비교하고자 하였다. 환자의 동의하에 충치, 치주염이 없이 교정발치된 치아의 치주인대세포를 배양하여 건강한 치주인대섬유모세포로, 만성치주염으로 발거된 치아에서 채취하여 배양한 세포를 염증성 치주인대섬유모세포로 선정하였다. 구강에서 채취한 치은결체조직에서 배양한 사람치은섬유모세포를 일차 배양한 후 계대배양을 통해 복제 노화를 유도하였다. $-198^{\circ}C$의 액화질소에 저장되어 있던 2, 4, 8, 15, 16세대 세포를 실험에 이용하였다. 위의 모든 세포들은 60 mm 배양접시에서 세포들이 80-90%의 밀생이 될 때까지 5% $CO_2$, $37^{\circ}C$, 100% 습도의 배양기에서 2일 간격으로 10% FBS가 함유된 DMEM 세포 배양액을 교체하면서 세포를 배양하였다. Trizol Reagent (Invitrogen, USA)를 이용하여 제조회사의 지시에 따라 total RNA를 추출하였다. 18S RNA와 28S RNA를 확인한 후 DNA microarray 분석을 실시하였다. 4배수 이상의 변화양상을 비교시 상호 유전자 발현의 차이를 나타내었다. 건강한 사람치은섬유모세포(2세대)와 노화된 치은섬유모세포에서 가장 높은 발현변화를 나타낸 반면 DMC1 dosage suppressor of mck1 homolog, meiosis-specific homologous recombination,은 건강한 치은섬유모세포에서 가장 높게 나타났다. 염증성 치은인대섬유모세포와 건강한 치주인대 섬유모세포를 비교시, Regucalcin은 염증성 치주인대섬유모세포에서 가장 높게 나타났고, Vascular cell adhesion molecule 1도 두 번째로 높게 나타났다. 건강한 치주인대섬유모 세포와 건강한 치은섬유모세포를 비교시, IL-11과 periostin이 치주인대섬유모세포에서 높은 발현을 나타낸 반면, Prostaglandin D2 synthase 21kDa과 Thioredoxin interacting protein은 치은섬유모세포에서 높은 발현을 나타내었다. 염증성 치주인대섬유모세포와 노화된 치은섬유모세포(15세대 이상)를 비교시 149개의 유전자가 유사한 발현 수준을 나타내었다. 이 연구는 노화, 염증, 세포 형태에 따라서 유전자 수준에서 가장 높거나 높은 수준 변화를 보이는 유전자가 다를 수 있음을 나타낸다. 향후, 치주염 환자들에서, 노염, 염증, 세포 특이성에 관한 유전자 표시지를 이용하여 진단하거나 치료에 응용하기 위해서는 더 많은 연구가 필요하리라 사료된다.