간세포암의 고주파 열치료 후 천자침 경로를 통한 전이 1례

조영완,박석주,진한영,김준영,이재익,강명주,박정하,윤정희,박성재,지삼룡,이연재,이상혁,설상영 인제대학교 2006 仁濟醫學 Vol.27 No.-

Radiofrequency ablation(RFA), as a form of minimally invasive therapy for hepatocellular carcinoma, has become an important treatment modality. Because of limitation of surgery, RFA has become standard therapy for hepatocellular carcinoma in some situations. But there are some complications of RFA such as bleeding, infection, hematoma, adjacent organ thermal damage including intestinal perforation, needle track seeding, and so on. There are few reports in the literature that systematically evaluate the incidence of needle tract seeding and its associated risk factors. And only 2 cases of needle tract seeding of hepatocellular carcinoma after RFA were reported in Korea. We report a case of needle tract seeding of hepatocellular carcinoma after RFA.

Electropulsing Treatment on Enhancement of Electrical Conductivity of Screen-Printed Ag Wire

Ju‑Won Park,Howook Choi,Hwangsun Kim,Simoon Sung,Hye‑Jin Jeong,Il Kim,Jaeseok Gong,Sung‑Tae Hong,Heung Nam Han 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

The effect of high electric current density on the sintering of Ag wires manufactured by screen printing is evaluated throughelectrical resistivity analysis and microstructure observation. Different forms (continuous and pulsed) of electric currentwith different current densities are applied to the specimens. Conventional heat treatment is also performed as a controlgroup to examine the athermal effect of electropulsing treatment. Compared to the conventional heat treatment, the resistivityis reduced more under the electropulsing treatment with continuous current for the same temperature and treatment time.Also, the process time of electropulsing treatment can be reduced by applying a pulse form of high density current insteadof continuous current without losing the benefit of enhanced reduction of resistivity. The microstructural observationsobtained from high angle annular dark field scanning transmission electron microscope and a digital precession instrumentclearly show that necking connecting the crystals is formed more firmly under electric current. In addition, the temperaturechange of Ag wire and substrate is calculated according to the change of the resistivity when the electric current is appliedto confirm the reliability.

Influence of Phase Composition in TiAlSiN Hard Coatings on the Evolution of Structure and Mechanical Properties

Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

The aim of this study is to investigate the structural evolution and mechanical properties of TiAlSiN coatings when processedby the arc ion plating method. To form a hard coating, Ti, Al, and Si powders were mechanically alloyed by planetary ballmilling; the powders were then densely compacted during a rapid sintering process into a ternary system coating, i.e. TiAlSi. The evolution of the structural phase from a powder to a compact material is dominated considerably by phase states suchas a supersaturated solid solution or intermetallic compounds. In the case of coating layers, the factors that determine thestructural evolution are associated with the phase stability of the nano-crystalline structure that in turn is associated withthe Ti/Al composition ratio. Motivated by this, we performed experiments to investigate the distribution of microstructures;the material’s binding energy, quantitative properties, transformation of crystal structure, and distribution of amorphous/crystalline were all recorded. In particular, the relationship between the physical and chemical properties during the coatingprocess is considered to be the dominant factor controlling the orientation and morphology of that zone (1, T, and 2). TheTiAlSiN coating layer was found to have hardness above 45 GPa and an adhesion above 100 N. In other words, understandingthe evolution and structure of TiAlSin helped us to produce a material with excellent properties that can be used as a hardcoating. Specifically, these properties were induced by a grain refinement of the nano-crystalline structure that correspondsto an increase in the silicon nitride contents.

초경합금 소재 LCU_CL 코어의 초정밀 연삭 특성에 관한 연구

정상화,차경래,김현욱,이봉주 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-

As the various manufacturing technology of optical glass is developed, the aspherical lenses are applied to many fields. However, It is still very difficult to manufacture glass lens because of the high cost and the short life of core. In recent years, the demands of the aspherical glass lenses increase since it is difficult to obtain the desirable performance in the plastic lens. In the glass mold lens, it has merits of high productivity and reproductivity since lens is manufactured by the only forming with high precision mold. The fabricating conditions for glass mold lens are glass surface that does not cause fusion, viscosity of 108-1013 poise for the 0.2㎛ accuracy, and viscoelasticity for the roughness less than 100 angstrom. In this thesis, ultra-precision grinding characteristics of tungsten carbide for forming the aspherical glass lens core were studied and the result of it is applied to manufacture the tungsten carbide-base core of the glass lens used to the laser scanning unit and the camera phone.

타타늄의 열처리 조건에 따른 동전위 양극분극특성 및 표면 미세구조 변화

주동현,이용렬,정영화,양홍서,박상원,이도재,송호준,박영준 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.2

The corrosion resistance of metallic implants is essential for successful implant osseointegration. Moreover, the implant surface should have appropriate surface roughness for the attachment of the osteoblast and collagen fibrils. When titanium is exposed to air a thermodynamically very stable oxide film is formed at once. This oxide is very thin and yet it protects the metal from corrosion instantaneously. However, the oxide would not be ideal, and it would be supposed that the state of oxide film would be various by the different conditions when it is formed. The objective of this study was to evaluate the electrochemical properties and surface microstructural changes of titanium after passivation treatment or exposure to high heat (in vacuum or in air). ASTM grade 2 commercially pure titanium (Ti) disks of 10㎜ diameter were wet ground and polished with 240 and 600 grit SiC, and then ultrasonically cleaned with distilled water and ethanol. Cleansed as-received samples (As-R group) were passivated with 30% nitric acid solution at 50℃ for 15 minutes to make the Pas group. The Std-V samples were made by treating the Ti disks in vacuum quartz tube (10^-8 Torr) at 530℃ for 40 min for stress relieving, followed by annealing at 700℃ for 90 min, and then slow cooling to room temperature. The Std-A samples undergo identical procedure as the Std-V group except that it is done in air. For 530℃-V samples, Ti disks were heated at 530℃ for 40 minutes and slow cooled to room temperature. The 1000℃-V samples were produced by heating Std-V specimens again at 1000℃ for 2 hr, followed by cooling to room temperature. 530℃-A and 1000℃-A samples were also prepared. Potentiodynamic anodic polarization measurement, SEM, AFM and XRD analysis were performed to evaluate the effects of the various treatments. The difference in the mean values of E_corr between groups showed statistically significant difference (P<0.05), but that of I_corr did not show significance (P>0.05). When Ti surface was passivated there was a shift of corrosion potential (E_corr) in the noble direction and a lower corrosion current density (I_corr) value. Std-A samples showed most noble E_corr value among the tested groups. 530℃-V samples showed more noble E-corr than other tested groups except Std-A group. 1000℃-V samples showed more noble E-corr than those of Std-V sample. In the case of Std-, 530℃- and 1000℃-groups, -A sub-groups showed better corrosion resistant characteristics than -V sub-groups in regard to E-corr and I_corr values. In the SEM observations, the surfaces of the As-R samples showed only scratch line on smooth surface. In Pas samples, thick oxide layer covered the surface under high magnification observation. 530℃-A samples were covered by oxide granules, and Std-A samples had 25~50 nm-thick acicular oxides. The 1000℃-A samples were covered by coarse oxide crystals with a granule diameter of 0.1~0.6 μm having a gross appearance of milky white color, which was identified by XRD as a rutile. On the other hand, 1000℃-V samples showed an Widmansta¨tten structrue of which the orientation of the lattice is formed along crystallographic planes of the parent crystals. On the AFM observation, 530℃-A samples showed RMS roughness of 79.38 nm which is 5 times rougher than those of the As-R samples. Std-A sample had a roughness of 330.47 nm which is about 20-times rougher than that of the As-R sample. 1000℃-A samples were covered by coarse granular oxides and the roughness were about 0.56 μm. Vacuum sub-group samples showed a more smooth surface than air sub-group samples, and the oxide film was more dense. Due to variability of the surface treatment and heat treatment conditions, the process of the oxide formation seems to be affected thereby making the corrosion properties and surface micro-morphology different. However, more various electrochemical analysis together with surface analysis, and an investigation for the effects of those on the osteoblast cell adhesion and calcium phosphate apposition are needed for the improvement of the osseointegration rates of the titanium implants.

민감도 분석을 이용한 필릿용접용 용접변수 선정에 관한 연구

정재원,김일수,김학형,손성우,김인주,전광석 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

Arc welding process is one of the most important technologies to join metal plates. Robotic welding offers the reduced manufacturing cost sought, but its widespread use demands a means of sensing and correcting for inaccuracies in the part, the fixturing, and the robot. A number of problems that need to be addressed in robotic arc welding processes include sensing, joint tracking, and lack of adequate mathematical models for parameter prediction and quality control, Problems with parameter settings and quality control occur frequently in the GMA(Gas Metal Arc) welding process because of the large number of interactive parameters that must be set and accurately controlled. The objectives of this paper are to realize the mapping characteristics of bead width using a sensitivity analysis and develop the neural network and multiple regression method, and finally select the most accurate model in order to control the weld qua1ity(bead width) for fillet welding. The experimental results show that the proposed neural network estimator can predict bead width with reasonable accuracy, and guarantee the uniform weld quality.

보툴리눔 독소 주사 효과의 정량적 분석을위한 복합근활동전위 측정

서정환,김상수,김남균,이주홍 大韓再活醫學會 1998 Annals of Rehabilitation Medicine Vol.22 No.6

우리 나라 有機農産物 品質認證制度에 관한 硏究

鄭淳宰,吳柱成,朴興植 東亞大學校 1998 東亞論叢 Vol.35 No.-

It shows a marked trend increasing the products of organic agriculture with growing interest in peoples health and safe foodstuffs. This is in the cause of the consuming public using habitually of safety and tasty organic agricultural products for reasons of environment pollution, environment hormone and etc. Now in Korea, organic agricultural products must be approved by our government of its quality, there fore organic agricultural products, that of transition period, non- chemicals agricultural products and less chemicals agricultural products are in cultivation separately. With the increase in number of consumers in future, we have to extend the products of the organic agriculture and have to control more strictly the quality guaranteed. Also, we must grope for developing of our organic agricultural products so that our producer can work with a strong will to attain self-sufficiency of our foodstuffs, paying our influence of environment.

구간분할 제어를 이용한 형상기억합금 와이어의 히스테리시스 특성에 관한 연구

정상화,김주환 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

Shape memory alloy(SMA) is one of artificial actuators used in the anthropomorphic robot hand. It generates displacement by input of heat or electric current on the entire SMA wire. SMA has a prominent strain hysteresis and its phase transition is dependent on temperature, stress and the direction of motion. Conventional control methods of SMA wire use the analogue, approach such as Galerkin method, Preishach method, slide mode, neural fuzzy, etc. The position control of SMA which uses the analogue approach is difficult. In this paper, the hysteresis characteristics of SMA wire using segment control is studied. SMA wire is controled by the digital approach. Thermo-electric module(TEM) which can heat and cold the same surface using the h-bridge circuit is used for segmenting a SMA wire and hysteresis of segmented SMA wire is measured.

구간 분할 제어를 이용한 형상기억합금 와이어의 온도제어에 관한 연구

정상화,김주환,김태호,서호진,박진완 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1

The key technology of robot is the design of the actuator. Particularly breakthroughs of power-to-weight ratio or energy-density III actuator technology have significant impacts upon the design and the control of robotic systems. To realize the anthropomorphic motion, artificial muscles such as shape memory alloy(SMA) and electro active polymer(EAP) are used. These actuators have the higher energy density than the electromechanical actuators such as the electric motor. The EAP has the property of good elasticity, but it is difficult to get the required power. The SMA has the good power density and simple structure, but the control scheme of the actuator is difficult. In this paper, temperature control of SMA wire using segment control is studied. The SMA wire is segmented by thermo-electric module(TEM). To supply constant currents in TEMs, MOSFET is used. Hysteresis in one segment of SMA wire is evaluated. The force and displacement of SMA wire are measured according to the number of segment. The program to control the temperature of TEM is developed by using LabVIEW software.