• Electrical & Electronic Materials
• /
• v.9 no.3
• /
• pp.240-245
• /
• 1996

Non-ozone layer destructive Chlorofluorocarbon(CFC) altematives(CHCIF$_{2}$ and $C_{2}$H$_{2}$F$_{4}$) have been initially used for laser-induced thenrmochemical etching of GaAs. High etching rate up to 188.mu.m/sec and an aspect ratio of 2.7 have been achieved by a single scan of laser beam, respectively. The etching rate at constant ambient gas pressure was found to saturate for beam power. The chemical compositions of the reaction products deposited on the etched groove were measured by Auger electron microscopy(AES). Etched profile, depth and width were observed by scanning electron microscope(SEM).

• BMB Reports
• /
• v.30 no.5
• /
• pp.315-319
• /
• 1997

It was discovered that monoclonal anti-erythropoietin (EPO) antibody CFC-6 can neutralize EPO-induced cell activation. To know the binding site of CFC-6, recombinant human erythropoietin (rhEPO) was digested with Glu-C, followed by a separation using high performance liquid chromato graphy (HPLC). Each HPLC fraction was blotted on the nitrocellulose membrane and the membrane was treated with anti-EPO antibody CFC-6 and anti-mouse antibody which is modified with peroxidase. Only one spot showed the color and the fraction was sequenced by Edman degradation. The results suggest that CFC-6 recognizes amino acid sequence V63-W-Q-G-L-A-L-L-S-E72 which is a part of helix II of the EPO molecule. Binding of CFC-6 to EPO may inhibit EPO binding to its receptor, which implies that the antibody binding site and the receptor binding site are close or overlapping.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.9
• /
• pp.2316-2327
• /
• 1995

Experimental results from nucleate pool boiling heat transfer with various finned tubes in CFC11, HCF123 and HCFC141b are reported. One plain tube and four low fin tubes of various fin densities were tested in an attempt to find out the optimum fin density in the heat flux range of 10-60 kW/m$^{[-992]}$ at near atmospheric pressure. The results indicated that CFC11 showed the highest heat transfer coefficients. Its alternatives, HCFC123 and HCFC141b, showed 3-5% lower heat transfer coefficients than those of CFC11 at the same heat flux. As the fin density increases, so does the heat transfer surface area. Measured heat transfer coefficients, however, do not necessarily always increase as the fin density increases. This unique phenomenon seems to be caused by the coalescence of the bubblers that prevent the cool liquid from entering into the fin valleys. For all the refrigerants tested, the optimum fin density yielding the highest performance was 28 fins per inch confirming the previous results by other researchers.

• Journal of Power Electronics
• /
• v.16 no.5
• /
• pp.1743-1751
• /
• 2016

The increasing demand for high voltage DC grids resulting from the continuous installation of offshore wind farms in the North Sea has led to the concept of multi-terminal direct current (MTDC) grids, which face some challenges. Power (current) flow control is a challenge that must be addressed to realize a reliable operation of MTDC grids. This paper presents a reduced switch count topology of a current flow controller (CFC) for power flow and current limiting applications in MTDC grids. A simple control system based on hysteresis band current control is proposed for the CFC. The theory of operation and control of the CFC are demonstrated. The key features of the proposed controller, including cable current balancing, cable current limiting, and current nulling, are illustrated. An MTDC grid is simulated using MATLAB/SIMULINK software to evaluate the steady state and dynamic performance of the proposed CFC topology. Furthermore, a low power prototype is built for a CFC to experimentally validate its performance using rapid control prototyping. Simulation and experimental studies indicate the fast dynamic response and precise results of the proposed topology. Furthermore, the proposed controller offers a real solution for power flow challenges in MTDC grids.

• Applied Chemistry for Engineering
• /
• v.10 no.2
• /
• pp.237-241
• /
• 1999

Nickel was impregnated on the $SiO_2$ and $Al_2O_3$ supports and applied to the reduction reaction of CFC-113 ($CF_2Cl$-$CFCl_2$) with hydrogen to 3FCl ($CF_2$=CFCl, CFC-1113). The conversion was rapidly declined on the Ni/$SiO_2$(or $Al_2O_3$) and the deactivation accelerated as the increase of Ni content. However, the selectivity of 3FCl was maintained at around 80% level. The simultaneous coprecipitation of copper and lithium on Ni/$Al_2O_3$ improved both the conversion and selectivity to 3FCl, but an excessive amount of lithium reduced the conversion as well as the selectivity of 3FCl. However, in the case of Ni/$SiO_2$, the conversion was greatly reduced possibly due to a loss of silica support with high surface area by the reaction of $SiO_2$ with HF. Such a reduction in conversion also can be ascribed to the decrease in active sites, caused by the addition of alkali metal compound, LiOH.

• Applied Chemistry for Engineering
• /
• v.4 no.2
• /
• pp.318-323
• /
• 1993

Pentachloroethane($CHCl_2CCl_3$) was synthesized and reacted with hydrogen fluoride using antimony pentahalide catalyst($SbCl_xF_y$) in order to manufacture HCFC-123$(CF_3CHCl_2)$, a potential CFC-11$(CFCl_3$) substitute candidate. Products analyses showed the fluorination proceeds through fluorine-chlorine exchanges between $HF/SbCl_xF_y$ and $SbCl_xF_y/CCl_3CHCl_2$ respectively. The degree of fluorination of $CCl_3$ group in pentachloroethane was greatly affected on the reaction temperature, but the effect of catalyst concentration was relatively small. Mechanistic study was also performed to elucidate the pathway to the formation of side-products such as $CCl_3CFCl_2$, $CFCl_2CFCl_2$ and $CF_2ClCFCl_2$.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.25 no.1
• /
• pp.53-66
• /
• 1996

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 1992.10a
• /
• pp.96-100
• /
• 1992

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.20 no.3
• /
• pp.179-189
• /
• 1991

• The Monthly Technology and Standards
• /
• s.1
• /
• pp.64-68
• /
• 2002