• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.1
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• pp.72-78
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• 2004

In this paper, mechanical behaviors of developed pedicle screw system, made of bio-mechanical materials(Ti-6Al-4V, Grade 5), ale predicted using FEM analysis. As a first step, morphologic construction of normal Korean spines and surgical operation convenience are considered to design optimum pedicle screw system. In this step, various design variables are considered as design parameters to develop optimized models. As a next step, tension and bending tests are performed to improve the structural performance of the developed system using finite element method. In this step, required Static compression and bending test specifications by ASTM F-04 25 04 01 are applied to understand the bio-mechanical behaviors of the designed spinal implant system under various load types. As the results of this research, it is possible to develop efficient pedicle screw system, having enough rigidity and fixation to stand any spinal damage under allowable stress conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1076-1079
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• 2001

This investigation reports the grinding characteristics of titanium alloy(Ti-6Al-4V). Grinding experiments were performed at various grinding conditions. The grinding forces and grinding force ratio were measured to investigate the grindability of titanium alloy with the Diamond and CBN wheel. To investigate the grinding characteristics of titanium alloy grinding force ratio and grinding ratio were measured. Surface profile of wheel was also measured with tracer and the ground surfaces and chip were observed with SEM. Grinding-ratio of titanium alloy was much lower than that of other materials. Grinding-ratio of titanium alloy with Diamond wheel was almost six times larger than that with CBN wheel.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.425-432
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• 2012

This paper investigates shape design processes of two implant systems for bone fracture treatment ; Bone plate and Interlocking nail system. These systems can directly fix fractured human bones by surgical operations. The bone plates consist of various shaped plates and implant screws for fixation of fractured human bones with various manual instruments allowing to handle them. The material corresponds to titanium alloy Ti6Al4V because it is harmless material for human body as well as significantly rigid. This system has to be suitably rigid as well as manually bended in orthopedic surgery operations. The Interlocking nail system is a kind of nail implanted inside fractured human bones. The shapes of these systems have to be suitably designed in order to endure various loads as well as avoid any damages. If various shaped prototypes would be fabricated and tested to design the optimal shapes, optimal shapes could be obtained but very long time and expensive costs must be required. In this paper finite element method was applied into these systems. Under various boundary conditions a series of structural analysis was conducted by using ANSYS. Finally important shape factors could be determined on the basis of the analysis results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1122-1126
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• 2017

KSLV-II ullage motor is a type of the separation motor of Korea Space Launch Vehicle. Simultaneously operates with the retro Motor to perform the stage separation. The internal ballistics design, application of propellant composition, and the design of the combustion chamber and the canted nozzle were performed in accordance with the target performance of the ullage motor. Ti-6Al-4V alloy was applied to the combustion as material of chamber and nozzle. The heat resistant material of the nozzle was selected to ensure the heat resistance of the propellant containing a large amount of aluminum. And the combustion performance of the ullage motor satisfying the KSLV-II requirements was secured by performing the ground combustion test.

• Transactions of Materials Processing
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• v.33 no.2
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• pp.96-102
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• 2024

This study addresses evaluation of performance of hardening model for a titanium alloy (Ti6Al4V) based on the artificial neural network (ANN) regarding the strain rate and the temperature. Uniaxial compression tests were carried out at different strain rates from 0.001 /s to 10 /s and temperatures from 575 ℃ To 975 ℃. Using the experimental data, ANN models were trained and tested with different hyperparameters, such as size of hidden layer and optimizer. The input features were determined with the equivalent plastic strain, strain rate, and temperature while the output value was set to the equivalent stress. When the number of data is sufficient with a smooth tendency, both the Bayesian regulation (BR) and the Levenberg-Marquardt (LM) show good performance to predict the flow behavior. However, only BR algorithm shows a predictability when the number of data is insufficient. Furthermore, a proper size of the hidden layer must be confirmed to describe the behavior with the limited number of the data.

• Biomedical Engineering Letters
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• v.8 no.4
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• pp.337-344
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• 2018

Additive manufacturing (AM) is an alternative metal fabrication technology. The outstanding advantage of AM (3D-printing, direct manufacturing), is the ability to form shapes that cannot be formed with any other traditional technology. 3D-printing began as a new method of prototyping in plastics. Nowadays, AM in metals allows to realize not only net-shape geometry, but also high fatigue strength and corrosion resistant parts. This success of AM in metals enables new applications of the technology in important fields, such as production of medical implants. The 3D-printing of medical implants is an extremely rapidly developing application. The success of this development lies in the fact that patient-specific implants can promote patient recovery, as often it is the only alternative to amputation. The production of AM implants provides a relatively fast and effective solution for complex surgical cases. However, there are still numerous challenging open issues in medical 3D-printing. The goal of the current research review is to explain the whole technological and design chain of bio-medical bone implant production from the computed tomography that is performed by the surgeon, to conversion to a computer aided drawing file, to production of implants, including the necessary post-processing procedures and certification. The current work presents examples that were produced by joint work of Polygon Medical Engineering, Russia and by TechMed, the AM Center of Israel Institute of Metals. Polygon provided 3D-planning and 3D-modelling specifically for the implants production. TechMed were in charge of the optimization of models and they manufactured the implants by Electron-Beam Melting ($EBM^{(R)}$), using an Arcam $EBM^{(R)}$ A2X machine.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.24-24
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• 2015

최근 생체재료의 개발이 눈부시게 발전되고 생체적합성이 우수한 표면을 요구함에 따라 생체재료의 표면처리에 대한 연구가 활발히 진행되고 있다. Laser Deposition법은 항공기 부품제조 분야에 주로 사용되고 있으며 최근에 오하이오 주립대 타이타늄합금연구센터를 중심으로 표면처리에 관한 연구가 주로 이루어졌다. 특히 이를 이용하여 치과재료의 표면처리에 응용을 시도하였다. 치과에서 응용될 수 있는 경우는 주로 임플란트는 부분 또는 완전 무치악 환자의 보철수복에 사용되는 보철물의 제작등에 사용될 수 있으며 이중에서도 특히 생체용 임플란트의 표면처리응용으로 임플란트와 조직간의 접합성을 개선하는 표면처리법으로 연구되었다. 임플란트의 성공과 실패는 물성적인 측면에서 임플란트의 형태, 표면거칠기 및 표면처리방법, 초기하중 등에 의하여 좌우되며 임플란트 재료에 작용하는 응력차폐는 생체적합성을 좌우하는 큰 요인이 되고 있다. 이를 위하여 저 탄성계수합금을 설계하지만 하중을 버티는 강도가 낮아지는 단점이 있어 레이저증착법을 이용하여 임플란트재료인 Ti6Al4V합금에 탄성계수가 낮은 Ta, Nb등을 코팅하는 방법을 통하여 이를 해결하고자하는 시도가 이루어지고 있다. 이 방법은 최근의 3D 프린팅의 원리가 되고 있다. 따라서 발표에서는 Laser Deposition방법을 이용하여 치의학분야에서 응용되고 있는 예를 강연하고 응용 가능 분야에 대하여 토론 하고자한다. 또한 펨토레이저를 이용하여 생체합금의 표면처리는 생체활성화를 더욱 증진시키며 이를 위하여 많은 연구 수행되고 있다. 본 발표에서는 매식용 합금 표면에 펨토레이저를 이용하여 텍스춰링하여 세포가 잘 성장 할 수 있는 크기의 조절함으로써 기존의 표면처리와는 다른 효과를 얻을 수 있는 장점을 알아본다. 펨토레이저를 이용하면 여러 가지 형태의 텍스춰링이 가능하며 원형, 사각형등등 자유자제로 형태의 묘사가 가능하고 깊이 또한 쉽게 조절할 수 있는 장점이 있다. 지금까지는 표면 개질에 사용되는 레이저는 주로 Nd:YAG 레이저의 파장을 반으로 줄인 녹색레이저 (${\lambda}=532nm$)를 사용하거나, 자외선파장영역의 레이저를 사용하는 경우가 일반적으로 가장 보편화되었다. 이를 이용하여 제조된 Ti합금에 펨토 초(10-15 second) 펄스폭 대역을 갖는 레이저를 이용하여 나노크기의 미세 요철을 표면에 형성한 후, 나노튜브를 형성하여 그 표면특성의 변화를 알아보고 펨토레이저가 의료분야에 적용되고 있는 예를 살펴보고자 한다.

• Economic and Environmental Geology
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• v.31 no.4
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• pp.297-310
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• 1998

Geochemical characteristics of environmental toxic elements at the Narim mine area were investigated on the basis of major, minor, rare earth element geochemistry and mineralogy. Ratios of $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ in soils and sediments range from 11.57 to 22.21 and from 1.86 to 3.93, and are partly negative and positive correlation against $SiO_2/Al_2O_3$ (3.41 to 4.78), respectively. These suggested that sediment source of host granitic gneiss could be due to rocks of high grade metamorphism originated by sedimentary rocks. Characteristics of some trace and rare earth elements of V/Ni (0.33 to 1.95), Ni/Co (2.00 to 6.50), Zr/Hf (11.27 to 53.10), La/Ce (0.44 to 0.55), Th/Yb (4.07 to 7.14), La/Th (2.35 to 3.93), $La_N/Yb_N$ (6.58 to 13.67), Co/Th (0.63 to 2.68), La/Sc (3.29 to 5.94) and Sc/Th (0.49 to 1.00) are revealed a narrow range and homogeneous compositions may be explained by simple source lithology. Major elements in all samples are enriched $Al_2O_3$, MgO, $TiO_2$ and LOI, especially $Fe_2O_3$ (mean=7.36 wt.%) in sediments than the composition of host granitic gneiss. The average enrichment indices of major and rare earth elements from the mining drainage are 2.05 and 2.91 of the sediments and are 2.02 and 2.60 of the soils, normalizing by composition of host granitic gneiss, respectively. Average composition (ppm) of minor and/or environmental toxic elements in sediments and soils are Ag=14 and 1, As=199 and 14, Cd=22 and 1, Cu=215 and 42, Pb=1770 and 65, Sb=18 and 3, Zn=3333 and 170, respectively, and extremely high concentrations are found in the subsurface sediments near the ore dump. Environmental toxic elements were strongly enriched in all samples, especially As, Cd, Cu, Pb, Sb and Zn. The level of enrichment was very severe in mining drainage sediments, while it was not so great in the soils. Based on the EPA value, enrichment index of toxic elements is 8.63 of mining drainage sediments and 0.54 of soils on the mining drainage. Mineral composition of soils and sediments near the mining area were partly variable being composed of quartz, mica, feldspar, amphibole, chlorite and clay minerals. From the gravity separated mineralogy, soils and sediments are composed of some pyrite, arsenopyrite, chalcopyrite, sphalerite, galena, goethite and various hydroxide minerals.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.117-117
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• 2016

Total ankle replacement (TAR) is a visible option in the surgical treatment of degenerative or inflammatory diseases of ankle joint. it is attributed to the current TAR which has improvements in surgical technique, uncemented implant fixation and minimally constrained articulation. In the clinical result, they can show promised surgical result when compared to earlier attempts in TAR. However, TAR is still not as successful as total knee replacement (TKR) or total hip replacement (THR), it needs to be note that there are limitations in concerning of long term performance of TAR, the high failure rate still associated with wear of the PE (polyethylene) component that has related with their material property and surface roughness. The aim of this study was to introduce the tribology characteristics of total ankle joint prosthesis with one of TDR model which was fabricated to try multi-axis wear test as a region of motion in ankle joint. The wear specimen of TDR was prepared with Ti-6Al-4V alloy and UHMWPE (ultra-high molecular weight polyethylene) for tibia-talus and bearing component, respectively. A wear test was carried out using a Force 5 (AMTI, Massachusetts, US) wear simulator which can be allowed to move in three axis to flexion-extension ($+3^{\circ}{\sim}-6^{\circ}$), internal-external axial rotation (${\pm}5^{\circ}$), as well as sinusoidal compressive load (1.6 kN, R=10). All tests were performed following standard ISO 14243, wear rate was calculated with weight loss of UHMWPE bearing while the specimen has tested at certain cycles. As based on the preliminary results, wear rate of UHMWPE bearing was $7.9{\times}10^{-6}mg/cycles$ ($R^2=0.86$), calculated loss weight until $10^7cycles$ was 79 mg, respectively.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.675-687
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• 2006

The purpose of this study is to determine the geochemical characteristics of the stream sediments in the Cheongpung area. So that we can understand the natural background and predict the prospects of geochemical disaster, if any. We collected the stream sediments samples by wet sieving along the primary channels and slow dried the collected samples in the laboratory and ground them to pass a 200 mesh using an alumina mortar and pestle for chemical analysis. Miner-alogical characteristics, major, trace and rare earth elements were determined by XRD, XRF, ICP-AES and NAA analysis methods. For geochemical characteristics on the geological group of stream sediments, the studied area was grouped into granitic gneiss area, metatectic gneiss area, Dado tuff area, Yuchi conglomerate area, and Neungju flow area in the Cheongpung area. Contents of major elements for the stream sediments in the Cheongpung area were $SiO_2\;47.31{\sim}72.81\;wt.%,\;A1_2O_3 \;11.26{\sim}21.88\;wt.%,\;Fe_2O_3\;2.83{\sim}8.39\;wt.%,\;CaO\;0.34{\sim}7.54\;wt.%,\;MgO\; 0.55{\sim}3.59\;wt.%,\;K_2O\;1.71{\sim}4.31\;wt.%,\;Na_2O\;0.56{\sim}2.28\;wt.%,\;TiO_2\;0.46{\sim}1.24\;wt.%,\;MnO\;0.04{\sim}0.27\;wt.%,\;P_2O_5\;0.02{\sim}0.45\;wt.%$. The con-tents of trace and rare earth elements for the stream sediments were $Ba\;700ppm{\sim}8990ppm,\;Be\;1.0{\sim}3.50ppm,\;Cu\;6.20{\sim}60ppm,\;Nb\;12{\sim}28ppm,\;Ni\;4.4{\sim}61ppm,\;Pb\;13{\sim}34ppm,\;Sr\;65{\sim}787ppm,\;V\;4{\sim}98ppm,\;Zr\;32{\sim}164ppm,\;Li\;21{\sim}827ppm,\;Co\;3.68{\sim}65ppm,\;Cr\;16.7{\sim}409ppm,\;Cs\;2.72{\sim}37.1ppm,\;Hf\;4.99{\sim}49.2ppm,\;Rb\;71.9{\sim}649ppm,\;Sb\;0.16{\sim}5.03ppm,\;Sc\;4.97{\sim}52ppm,\;Zn\;26.3{\sim}375ppm,\;Ce\;60.6{\sim}373ppm,\;Eu\;0.82{\sim}6ppm,\;Yb\;0.71{\sim}10ppm$.