Industrial CO2 emissions from energy use in Korea: A structural decomposition analysis

This paper attempts to quantify energy consumption and CO₂ emissions in the industrial sectors of Korea. The sources of the changes in CO₂ emissions for the years 1990–2003 are investigated, in terms of a total of eight factors, through input–output structural decomposition analysis: changes in emission coefficient (caused by shifts in energy intensity and carbon intensity); changes in economic growth; and structural changes (in terms of shifts in domestic final demand, exports, imports of final and intermediate goods, and production technology). The results show that the rate of growth of industrial CO₂ emissions has drastically decreased since the 1998 financial crisis in Korea. The effect on emission reductions due to changes in energy intensity and domestic final demand surged in the second period (1995–2000), while the impact of exports steeply rose in the third period (2000–2003). Of all the individual factors, economic growth accounted for the largest increase in CO₂ emissions. The results of this analysis can be used to infer the potential for emission-reduction in Korea.     

Hydrogenated amorphous silicon thin-film transistor with a thingate insulator

Thinning the gate insulator in an hydrogenated amorphous silicon thin-film transistor (a-Si:H TFT) has been studied in a coplanar structure. The threshold voltage decreases with decreasing gate insulator thickness without changing the field effect mobility significantly. The reduction in the threshold voltage is due to the decrease in the charge traps in the SiN_x and in its film thickness. The coplanar a-Si:H TFT with a gate insulator thickness of 35 nm exhibited a field effect mobility of 0.45 cm²/Vs and a threshold voltage of 1.5 V. The thickness of the gate insulator can be decreased in the coplanar a-Si:H TFTs because of the planarized gate insulator     

A high performance thin-film transistor using a low temperaturepoly-Si by silicide mediated crystallization

Electric field enhanced silicide mediated crystallization (SMC) was introduced for low-temperature polycrystalline silicon thin-film transistors (TFTs) on glass substrates. The amorphous silicon (a-Si) film having an average Ni thickness of 0.15 Å, was completely crystallized at a temperature of 480°C within 30 min in the presence of an electric field of 40 V/cm. The poly-Si is composed of needlelike crystallites with a few μm length and about 50 nm width. The poly-Si TFT using the SMC exhibited a field effect mobility of 86 cm²/Vs, a threshold voltage of -0.6 V, and a subthreshold slope of 0.6 V/dec     

Grafting of poly(vinyl chloride) and polypropylene with styrene in a supercritical CO2 solvent medium: Synthesis and characterization

Graft copolymerization of styrene onto poly(vinyl chloride) (PVC) and polypropylene (PP) was carried out in a supercritical CO₂ medium using AIBN as a free radical initiator. The supercritical CO₂ medium served as a reaction medium in addition to being a solvent for the styrene monomer and the free radical initiator. The reaction temperature and pressure were kept above the critical points of the solvent‐monomer mixture to form a homogeneous single‐phase medium. The resulting graft copolymers were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR) techniques. The weight percent of grafting was determined using IR absorbance ratio technique. TGA results showed that the thermal stabilily of grafted copolymer of PVC was better than that of PVC, while grafted copolymer of PP had poorer thermal stability than PP. DSC results showed that glass transition temperatures (T_g's) of the grafted copolymers were higher than those of the starting polymers PVC and PP. The presence of polystyrene attached to the backbone polymer was confirmed by ¹H NMR and ¹³C NMR analyses.     

Force modeling and machining characteristics of the intermittent grinding wheels

In the surface grinding operations, the grinding fluid cannot be supplied sufficiently in the cutting zone. Temperature generated in the cutting zone increases rapidly and causes thermal damage such as burning on the surface of a workpiece. To reduce thermal damage, the intermittent grinding wheels, which have an excellent cooling effect, have been applied. This paper describes machining characteristics by using intermittent grinding wheels. The grinding force of the intermittent wheels has been simulated by the SIMULAB, which is a program for simulating dynamic systems. Using the intermittent grinding wheels, the characteristics of grinding force, temperature, surface roughness, and geometric error have been evaluated experimently.     

Blind adaptive multiuser detector for nonlinearly modulated satellite mobile CDMA systems

This paper presents a novel blind adaptive noncoherent decorrelative multiuser detector for nonlinearly modulated satellite mobile Code Division Multiple Access （CDMA） systems. By using the known signature waveforms of the counterpart earth station in the blind adaptive multiuser detector, the system performance has been improved obviously. The computation results about the convergence properties of the new detector and the previous detectors demonstrate that the proposed multiuser detector has better performance than previous multiuser detectors for nonlinearly modulated CDMA systems.     

Microstructural Developments and Tensile Properties of Lean Fe-Mn-Al-C Lightweight Steels

Concepts of Fe-Al-Mn-C-based lightweight steels are fairly simple, but primary metallurgical issues are complicated. In this study, recent studies on lean-composition lightweight steels were reviewed, summarized, and emphasized by their microstructural development and mechanical properties. The lightweight steels containing a low-density element of Al were designed by thermodynamic calculation and were manufactured by conventional industrial processes. Their microstructures consisted of various secondary phases as κ-carbide, martensite, and austenite in the ferrite matrix according to manufacturing and annealing procedures. The solidification microstructure containing segregations of C, Mn, and Al produced a banded structure during the hot rolling. The (ferrite + austenite) duplex microstructure was formed after the annealing, and the austenite was retained at room temperature. It was because the thermal stability of austenite nucleated from fine κ-carbide was quite high due to fine grain size of austenite. Because these lightweight steels have outstanding properties of strength and ductility as well as reduced density, they give a promise for automotive applications requiring excellent properties.     

Experimental Status of the HANBIT Facility

HANBIT is a magnetic mirror confinement device. Recent physics experiments have been mainly focused on identifying discharge characteristics and on getting stable plasma production and operation modes, by using a 500 kW slot antenna system at a fixed RF frequency of 3.5 MHz and varying discharge conditions such as fueling rate, RF power, and B-field intensity in central cell. Two distinct operation modes are found to be very sensitive to the RF power as well as the ratio of the RF frequency to the ion cyclotron frequency. A MHD interchange mode of m- -1 is clearly observed and the stabilizing mechanism can be explained by the sideband coupling theory.     

Optimization of microscale vortex generators in a microchannel using advanced response surface method

Mixing based on mass diffusion and advective flow at low Reynolds number is important on design of microscale vortex generators. We studied on the optimization of micromixer for the improvement of mass transport using an advanced response surface method to be closely approximate the real map of mixing performance. We considered four rib geometries simultaneously; rib angle, rib height, rib width, and rib spacing. The optimized microchannel was occurred at a micromixer configuration where θ, d/h, a/d, and b/d were 35.6°, 0.7, 0.127, and 1.10, respectively. The channel length to obtain the mixing uniformity over 95% was 1344 μm.     

Effect of nanoscale confinement on molecular mobility and drug release properties of cellulose acetate/sulindac nanofibers

Polymers confined in the nanoscale exhibit various unusual properties that are not seen in bulk polymers. Here, the effect of nanoscale confinement on the drug release properties of polymer nanofibers is investigated by analyzing the molecular mobility and drug release kinetics of cellulose acetate/sulindac nanofibers (CNs). It is observed that the activation energy, E_a, for molecular motion of both the main chain and side chain tended to increase as the diameter of the CNs decreased from 850 to 260 nm. The increased E_a indicates that the chains confined in ultrathin CNs are closely packed, resulting in a low molecular mobility. With decreasing diameter from 620 to 260 nm, the diffusion coefficient of drug is significantly decreased from 85.3 to 10.3 nm² min⁻¹. Such correlation between E_a and drug diffusion rate indicates that the confinement-induced suppression of the molecular motion could significantly affect the drug release properties of polymer nanofibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47863.