• Journal of Welding and Joining
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• 제26권5호
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• pp.36-42
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• 2008

Carbon nanotube (CNT) aluminum composite coatings were built up through kinetic spraying process. Deposition behavior of CNT aluminum composite on an aluminum 1050 alloy substrate was analyzed based on deposition mechanism of kinetic spraying. The microstructure of CNT aluminum composite coating were observed and analyzed. Also, the electrical resistivity, bond strength and micro-hardness of the CNT aluminum composite coatings were measured and compared to kinetic sprayed aluminum coatings. The CNT aluminum composite coatings have a dense structure with low porosity. Compared to kinetic sprayed aluminum coating, the CNT aluminum composite coatings present lower electrical resistivity and higher micro-hardness due to high electrical conductivity and dispersion hardening effects of CNTs.

• 한국분무공학회지
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• 제13권4호
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• pp.193-199
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• 2008

Spray coating is a versatile surface modification technology in which coating is built-up based on the successive deposition of micron-scaled particles. Depending on the coating materials, the coatings can meet the required mechanical properties, corrosion resistance, and other properties of base materials. Spraying processes are mainly classified into thermal and kinetic spraying according to their bonding mechanism and deposition characteristics. Specifically, thermal spraying process can be further classified into many categories based on the design and mechanism of the process, such as frame spraying, arc spraying, atmospheric plasma spraying (APS), and high velocity oxygen-fuel (HVOF) spraying, etc. Kinetic spraying or cold gas dynamic spraying is a newly emerging coating technique which is low-temperature and high-pressure coating process. In this paper, overall view of thermal and kinetic spray coating technologies is discussed in terms of fundamentals and industrial applications. The technological characteristics and bonding mechanism of each process are introduced. Deposition behavior and properties of technologically remarkable materials are reviewed. Furthermore, industrial applications of spray coating technology and its potentials are prospected.

• 한국분말재료학회지
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• 제23권1호
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• pp.8-14
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• 2016

A bulk-type Ta material is fabricated using the kinetic spray process and its microstructure and physical properties are investigated. Ta powder with an angular size in the range $9-37{\mu}m$ (purity 99.95%) is sprayed on a Cu plate to form a coating layer. As a result, ~7 mm-sized bulk-type high-density material capable of being used as a sputter material is fabricated. In order to assess the physical properties of the thick coating layer at different locations, the coating material is observed at three different locations (surface, center, and interface). Furthermore, a vacuum heat treatment is applied to the coating material to reduce the variation of physical properties at different locations of the coating material and improve the density. OM, Vickers hardness test, SEM, XRD, and EBSD are implemented for analyzing the microstructure and physical properties. The fabricated Ta coating material produces porosity of 0.11~0.12%, hardness of 311~327 Hv, and minor variations at different locations. In addition, a decrease in the porosity and hardness is observed at different locations upon heat treatment.

• BMB Reports
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• 제39권4호
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• pp.426-431
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• 2006

Embryonic stem cells (ESCs), representing a population of undifferentiated pluripotent cells with both self-renewal and multilineage differentiation characteristics, are capable of spontaneous differentiation into cardiomyocytes. The present study sought to define the kinetic characterization of lactate dehydrogenase (LDH) and creatine kinase (CK) of ESC- and neonatal-derived cardiomyocytes. Spontaneously differentiated cardiomyocytes from embryoid bodies (EBs) derived from mouse ESC line (Royan B1) and neonatal cardiomyocytes were dispersed in a buffer solution. Enzymes were extracted by sonication and centrifugation for kinetic evaluation of LDH and CK with spectrophotometric methods. While a comparison between the kinetic properties of the LDH and CK of both groups revealed not only different Michaelis constants and optimum temperatures for LDH but also different Michaelis constants and optimum pH for CK, the pH profile of LDH and optimum temperature of CK were similar. In defining some kinetic properties of cardiac metabolic enzymes of ESC-derived cardiomyocytes, our results are expected to further facilitate the use of ESCs as an experimental model.

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.208-209
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• 1989

• 한국지반공학회논문집
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• 제18권5호
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• pp.159-167
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• 2002

아연의 주물사에 대한 분배계수는 주물사에 포함된 TOC, 점토 함량, 총 철 함량 등에 따라 변하고 특히 용액 PH에 큰 영향을 받는 것을 관찰하였다. Batch 실험으로부터 얻어진 경험식으로부터분배계수와 제거상수를 예측할 수 있었다. Batch kinetic 실험과 batch sorption 실험으로부터 얻어진 분배계수는 용액 pH가 같을 시 거의 같은 값을 보이고 있다.

• 한국분말재료학회지
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• 제22권1호
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• pp.32-38
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• 2015

The effect of heat treatment environment on the microstructure and properties of tantalum coating layer manufactured by kinetic spraying was examined. Heat treatments are conducted for one hour at $800^{\circ}C$, $900^{\circ}C$, and $1000^{\circ}C$ in two different environments of vacuum and Ar gas. Evaluation of microstructure and physical properties are conducted. High density ${\alpha}$-tantalum single phase coating layer with a porosity of 0.04% and hardness of 550 Hv can be obtained. As heat treatment temperature increases, porosity identically decreases regardless of heat treatment environment (vacuum and Ar gas). Hardness of heat treated coating layer especially in Ar gas environment deceases from 550 Hv to 490 Hv with increasing heat treatment temperature. That in vacuum environment deceases from 550 Hv to 530 Hv. The boundary between particles became vague as heat treatment temperature increases. Oxygen distribution of tantalum coating layer is minute after heat treatment in vacuum environment than Ar gas environment.

• 한국분말재료학회지
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• 제23권1호
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• pp.15-20
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• 2016

Niobium is one of the most important and rarest metals, and is used in the electronic and energy industries. However, it's extremely high melting point and oxygen affinity limits the manufacture of Nb coating materials. Here, a Nb coating material is manufactured using a kinetic spray process followed by hot isotactic pressing to improve its properties. OM (optical microscope), XRD (X-ray diffraction), SEM (scanning electron microscopy), and Vickers hardness and EPMA (electron probe micro analyzer) tests are employed to investigate the macroscopic properties of the manufactured Nb materials. The powder used to manufacture the material has angular-shaped particles with an average particle size of $23.8{\mu}m$. The porosity and hardness of the manufactured Nb material are 0.18% and 221 Hv, respectively. Additional HIP is applied to the manufactured Nb material for 4 h under an Ar atmosphere after which the porosity decreases to 0.08% and the hardness increases to 253 Hv. Phase analysis after the HIP shows the presence of only pure Nb. The study also discusses the possibility of using the manufactured Nb material as a sputtering target.

• Archives of Pharmacal Research
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• 제27권9호
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• pp.968-972
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• 2004

A 1, 2-diglyceride-based multi-step colorimetric assay to measure the pancreatic lipase activ-ity was applied for the determination of the kinetic profiles of the lipase inhibition with a slight modification and the validity verification. With this assay method, our study revealed that platy-codin D, one of major constituents of Platycodi Radix, inhibits the pancreatic lipase activity in a competitive type, with the value of $K_1$ being 0.18${\pm}$0.02 mM. In addition, PO has affected the val-ues of $K_{m}$, app/ and $K_{cat}$/$K_{m}$ in a dose-dependent manner. The results shed a meaningful light on how PO mediates lipid metabolism in the intestinal tracts. On the other hand, since the revised assay is sensitive, rapid, and does not affect the accuracy to the kinetic properties, it is applica-ble not only to evaluation of the kinetic properties of the pancreatic lipase, but also to high-throughput screening of pancreatic lipase activity.

• Archives of Pharmacal Research
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• 제27권10호
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• pp.1048-1052
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• 2004

A 1, 2-diglyceride-based multi-step colorimetric assay to measure the pancreatic lipase activity was applied for the determination of the kinetic profiles of the lipase inhibition with a slight modification and the validity verification. With this assay method, our study revealed that platycodin D, one of major constituents of Platycodi Radix, inhibits the pancreatic lipase activity in a competitive type, with the value of $K_I$ being 0.18${\pm}$0.02 mM. In addition, PD has affected the values of $K_{m,app}\;and\;K_{cat}/K_m$ in a dose- dependent manner. The results shed a meaningful light on how PD mediates lipid metabolism in the intestinal tracts. On the other hand, since the revised assay is sensitive, rapid, and does not affect the accuracy to the kinetic properties, it is applicable not only to evaluation of the kinetic properties of the pancreatic lipase, but also to highthroughput screening of pancreatic lipase activity.