• Resources Recycling
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• v.4 no.3
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• pp.26-31
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• 1995

The leaching characteristics of manganese nodules were investigated in dilute hydrochloric acid solution using copper malie as a reductant. Thc capper matte has been found to be an effective reductant for exhacting morc than 96% of Mn, 95% of Ni, 91% of Ca, 88% of Cu and 36% of Fe when leached in 2.5 M HCI at 70$^{\circ}$C for 2hr. The dissolutions of Mu, Co, and Ni depend on thc amaunt of added cappcr matte. 7he ratin of liquid and solid is an important [actor on the extraction of metals during leaching The dissolution af Mn, Co, Ni and Cu incrcascd w~th the increase in temperalure of leachant. The leaching rates of Mn, Co, NI and Cu from manganese nodule m the presznce of copper matte is limited by bath thc surface chemical reaction and pare diffusion processes. Thc activation energies far Mn. Co: Ni and Cu were 17. 61, 12.8, 17.2 and 57.88 KcaUmol, rcspcctively.

• Macromolecular Research
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• v.16 no.2
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• pp.139-148
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• 2008

Biodegradable and elastic poly(L-lactide-co-$\varepsilon$-caprolactone) (PLCL) was electrospun to prepare nanofibers, and N-isopropylacrylamide (NIPAAm) was then grafted onto their surfaces under aqueous conditions using $^{60}Co-{\gamma}$ irradiation. The graft yield increased with increasing irradiation dose from 5 to 10 kGy and the nanofibers showed a greater graft yield compared with the firms. SEM confirmed that the PLCL nanofibers maintained an interconnected pore structure after grafting with NIPAAm. However, overdoses of irradiation led to the excessive formation of homopolymer gels on the surface of thc PLCL nanofibers. The equilibrium swelling and deswelling ratio of the PNIPAAm-g-PLCL nanofibers (prepared with 10 kGy) was the highest among the samples, which was consistent with the graft yield results. The phase-separation characteristics of PNIPAAm in aqueous conditions conferred a unique temperature-responsive swelling behavior of PNIPAAm-g-PLCL nanofibers, showing the ability to absorb a large amount of water at < $32^{\circ}C$, and abrupt collapse when the temperature was increased to $40^{\circ}C$. In accordance with the temperature-dependent changes in swelling behavior, the release rate of indomethacin and FITC-BSA loaded in PNIPAAm-g-PLCL nanofibers by a diffusion-mediated process was regulated by the change in temperature. Both model drugs demonstrated greater release rate at $40^{\circ}C$ relative to that at $25^{\circ}C$. This approach of the temperature-controlled release of drugs from PNIPAAm-g-PLCL nanofibers using gamma-ray irradiation may be used to design drugs and protein delivery carriers in various biomedical applications.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.263-266
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• 2000

This paper is focused on the fabrication of reliable Al/$TiO_2-SiO_2$/Mo antifuse, which could operate at low voltage along with the improvement in on/off state properties. Mo metal as the bottom electrode had smooth surface and high melting point, and was being kept as-deposited $SiO_2$film stable. The breakdown voltage of TiO_2-SiO_2$ stacked antifuse was better than that of same-thickness (100 $\AA$) $SiO_2$antifuse because of Ti diffusion in $SiO_2$. The improving breakdown-voltage and on-resistance can be obtained as well as the influence of hillock in the bottom metal is reduced by using double insulator. Low on-resistance (65 $\Omega$) and low programming voltage (9.0 V) can be obtained in these antifuses with 250 $\AA$ double insulator.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.77.1-77.1
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• 2013

Atomic layer deposition (ALD) is known for its self-limiting reaction, which offers atomic-level controllability of the growth of thin films for a wide range of applications. The self-limiting mechanism leads to very useful properties, such as excellent uniformity over a large area and superior conformality on complex structures. These unique features of ALD provide promising opportunities for future electronics. Although the ALD of Al2O3 film (using trimethyl-aluminum and water as a metal precursor and oxygen source, respectively) can be regarded as a representative example of an ideal ALD based on the completely self-limiting reaction, there are many cases deviating from the ideal ALD reaction in recently developed ALD processes. The nonconventional aspects of the ALD reactions may strongly influence the various properties of the functional materials grown by ALD, and the lack of comprehension of these aspects has made ALD difficult to control. In this respect, several dominant factors that complicate ALD reactions, including the types of metal precursors, non-metal precursors (oxygen sources or reducing agents), and substrates, will be discussed in this presentation. Several functional materials for future electronics, such as higher-k dielectrics (TiO2, SrTiO3) for DRAM application, and resistive switching materials (NiO) for RRAM application, will be addressed in this talk. Unwanted supply of oxygen atoms from the substrate or other component oxide to the incoming precursors during the precursor pulse step, and outward diffusion of substrate atoms to the growing film surface even during the steady-state growth influenced the growth, crystal structure, and properties of the various films.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.99-105
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• 2005

The mixing ratio effect of the GTD-111(base metal) powder and the GNI-3 (Ni-l4Cr-9.5Co-3.5Al-2.5B) powder on TLP(Transient Liquid Phase) bonding phenomena and mechanism was investigated. At the mixing ratio of the base metal powder under $50wt\%$, the base metal powders fully melted at the initial time and a large amount of the base metal near the bonded interlayer was dissolved by liquid inter metal. Liquid insert metal was eliminated by isothermal solidification which was controlled by the diffusion of B into the base metal. The solid phases in the bonded interlayer grew epitaxially from the base metal near the bonded interlayer inward the insert metal during the isothermal solidification. The number of grain boundaries farmed at the bonded interlayer corresponded with those of base metal. At the mixing ratio above $60wt\%$, the base metal powder melted only at the surface of the powder and the amount of the base metal dissolution was also less at the initial time. Nuclear of solids firmed not only from the base metal near the bonded interlayer but also from the remained base metal powder in the bonded interlayer. Finally, the polycrystal in the bonded interlayer was formed when the isothermal solidification finished. When the isothermal solidification was finished, the contents of the elements in the boned interlayer were approximately equal to those of the base metal. Cr-W borides and Cr-W-Ta-Ti borides formed in the base metal near the bonded interlayer. And these borides decreased with the increasing of holding time.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.37-43
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• 2009

Silicon dioxide as gate dielectrics was grown at $400^{\circ}C$ on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of $O_2$ and $N_2O$ to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature $N_2O$ annealing, nitrogen can be supplied to the $Si/SiO_2$ interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/$SiO_2$ interface by plasma oxidation as the $N_2O$ molecule is broken in the plasma and because a dense Si-N bond is formed at the $SiO_2$ surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the $Si/SiO_2$ interface by the plasma oxidation of mixtures of $O_2/N_2O$ gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.85-90
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• 2010

The infrared energy is emitted in the infrared wavelength range that corresponds to the surface temperature of a object which has temperature that is over the absolute the temperature(OK). The infrared thermography (IRT) is a non-destrnctive testing method that provides thermal video for the user in real-time by converting the infrared quantity that is detected by the infrared detector into temperature. The pipes of nuclear power plant(NPP) could be thinned by the corrosion and fatigue and the defect could lead to a big accident. For this reason, the effective non-destructive testing method is necessary. In this study, the relationship between the measured temperature and the defect depth or size of NPP pipes were recognized and that was applied to detect the wall thinning defects of NPP pipes.

• Fire Science and Engineering
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• v.32 no.3
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• pp.14-18
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• 2018

The earlier studies on the fire resistance performance of woods used as building materials have focused on confirming combustion characteristics of fire retardant or flame resistant treated wood. In this paper, to confirm internal temperature changes closely related to pyrolysis of woods exposed to the flame, heating experiments were conducted in a heating furnace according to the standard heating temperature curves after Douglas-fir, which is widely used as structural materials, was treated with a flame resistant solution and flame retardant paint. As a result of the experiment, it was confirmed that the thermal diffusion inside the wood has decreased when the wood was treated with the flame resistant solution. However, in high temperature, the flame resistant effect could not be expected due to the peeling of the coating in the case of the flame resistant paint treated wood. Therefore, it can be considered that it is more effective to use the flame resistant solution which penetrates in to the inside of the wood than flame resistant paint which forms the coating on the surface of the wood in order to enhance the flame resistance effect on the thick wood.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.276-279
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• 2004

Plasma enhanced chemical vapor deposition (PECVD) of silicon nitride (SiN) is a proven technique for obtaining layers that meet the needs of surface passivation and anti-reflection coating. In addition, the deposition process appears to provoke bulk passivation as well due to diffusion of atomic hydrogen. This bulk passivation is an important advantage of PECVD deposition when compared to the conventional CVD techniques. A further advantage of PECVD is that the process takes place at a relatively low temperature of 300t, keeping the total thermal budget of the cell processing to a minimum. In this work SiN deposition was performed using a horizontal PECVD reactor system consisting of a long horizontal quartz tube that was radiantly heated. Special and long rectangular graphite plates served as both the electrodes to establish the plasma and holders of the wafers. The electrode configuration was designed to provide a uniform plasma environment for each wafer and to ensure the film uniformity. These horizontally oriented graphite electrodes were stacked parallel to one another, side by side, with alternating plates serving as power and ground electrodes for the RF power supply. The plasma was formed in the space between each pair of plates. Also this paper deals with the fabrication of multicrystalline silicon solar cells with PECVD SiN layers combined with high-throughput screen printing and RTP firing. Using this sequence we were able to obtain solar cells with an efficiency of 14% for polished multi crystalline Si wafers of size 125 m square.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2384-2393
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• 2018

Porous alginate-based hydrogel beads (porous ABH) have been prepared through a facile and sustainable template-assisted method using nano-calcium carbonate and nano-$CaCO_3$ as pore-directing agent for the efficient capture of methylene blue (MB). The materials were characterized by various techniques. The sorption capacities of ABH towards MB were compared with pure sodium alginate (ABH-1:0) in batch and fixed-bed column adsorption studies. The obtained adsorbent (ABH-1:3) has a higher BET surface area and a smaller average pore diameter. The maximum adsorption capacity of ABH-1:3 obtained from Langmuir model was as high as $1,426.0mg\;g^{-1}$. The kinetics strictly followed pseudo-second order rate equation and the adsorption reaction was effectively facilitated, approximately 50 minutes to achieve adsorption equilibrium, which was significantly shorter than that of ABH-1:0. The thermodynamic parameters revealed that the adsorption was spontaneous and exothermic. Thomas model fitted well with the breakthrough curves and could describe the dynamic behavior of the column. More significantly, the uptake capacity of ABH-1:3 was still higher than 75% of the maximum adsorption capacity even after ten cycles, indicating that this novel adsorbent can be a promising adsorptive material for removal of MB from aqueous solution under batch and continuous systems.