Pt catalysts supported on Vulcan XC-72 carbon have been prepared with as metal precursor. Measurements of surface area and crystallite size by electrochemical method and by X-ray diffraction showed that the supported platinum crystallites grew when in contact with a electroconducting solution. This study shows that the platinum area loss depends on such factors as an initial crystallite size, platinum concentration, temperature and potential of electrode. A soluble platinum in conducting solution was redeposited on the electrode surface at cathodic potential, but there was no detectable area losses due to heating in nitrogen, argon or hydrogen at . In this study we will present the agglomeration phenomena of platinum particles and the reason of growth of platinum particles.

Microporous polypropylene hollow fiber membrane was prepared by the melt spinning and cold-stretching method. In order to measure the porosity of the hollow fiber membrane, bubble point measurement and microscopy of the both sides of a hollow fiber were done, and the area fraction and the volume fraction of micropores were estimated through image analyzer and mercury porosimeter. The bubble point of the of micropores were estimated through image analyzer and mercury porosimeter. The bubble point of the hollow fiber measured in 30%(v/v) aqueous ethanol solution was . Slit-shaped micropores were evenly spread all over the hollow fiber membrane, and parallel to the fiber axis with a stripe pattern. The micropores of the inside and the outside of the hollow fiber membrane have the similar morphology and their area fractions were 30-40%. Pore size distribution was tend to be normal, and the total volume fraction of the micropores was about 52%.

For the purpose of improving the use of raw materials, zinc acetate-2-water which is cheap and easy to handle was used to synthesize ZnO this films by thermal CVD method, which gave a good C-axis orientation even at atmospheric pressure and at relatively low temperature. The formation of ZnO films starts from and the deposition rate increases with increasing reaction temperature. The rate of deposition was affected by flow rates of and . Without the flow of , the oxygen required in synthesizing ZnO films was partially supplied by zinc acetate-2-water itself.

Effects of major casting variables such as the crucible cooling rate, rotation/translation of the crucible, wall thickness of the crucible, the coating material, and the class of feed silicon on the electro-physical properties of solar-grade polycrystalline silicon wafers were examined. The crystalline structures showed better columnar structures as the cooling rate was gradually reduced around the level of , and as proper rotation(1.5rpm)and translation(3.5cm/hr) of the crucible were performed at the same time. Impurity concentrations of cast wafers were on much lower levels than the limit values allowed for the high efficiency(i.e. above 10%) solar cells, irrespective of the kinds of feed silicons and coating materials. Within the proper ranges of above casting variables, it was feasible technically to manufacture the polycrystalline silicon wafers for the high efficiency solar cells using the impurity segregation effect and growth of the columnar structure due to the directional solidification phenomena of the present casting method.

The existing fault diagnosis methods using artificial neural networks do not deal with time varying symptoms of faults. But in real plants, because the effect of the fault propagates continuously with time, the changing values of various sensors provide valuable information for on-line fault diagnosis. This paper describes a new method in which time varying values of the measurements are used as the symptoms of the faults to train the artificial neural network. A fault diagnosis system for a distillation column based on the proposed method can accurately diagnose both single and multiple faults.

Boehmite AlO(OH) sol was prepared by sol-gel method from aluminum iso-propoxide under an acidic condition and this sol was coated on an alumina support. After it was dried for 2 days at room temperature and calcined at for one hour. The membrane had homogeneous ultra fine pores, about 3.0nm, with a narrow pore size distribution and the thickness was in the range of , depending upon the number of coatings. Gas permeation characteristics of the membrane with thickness were investigated for four gases He, . Knudsen diffusion was the dominant transport mechanism for these gases. But showed much higher permeabilities than the values predicted by Knudsen diffusion due to the effect of surface diffusion. The adsorption energy of obtained from adsorption iso-therms was 22.40kJ/mol and the calculated surface diffusion coefficients of turned out to be and at 290K, respectively. The additional flows by surface diffusion of was about 43% and 22% of the total flows, respectively. The separation factors of mixtures approached the theoretical values predicted by Knudsen diffusion with increasing temperature.

A series of aluminum-deficient mordenites were prepared by treating hydrogen mordenites with hydrochloric acid and hydrofluoric acid, respectively. Isotherms of nitrogen adsorption, XRD analysis, silicon NMR, and characteristics of cyclohexane adsorption were studied. Mordenites treated by hydrochloric acid formed secondary pores at more than of 30 and the crystal lattice contracted by removing frame-work aluminum. Mordenites treated by hydrofluoric acid made also secondary pores by extracting framework silicon simultaneously. For the treatment with hydrochloric acid, initial equilibrium constant, decreased continuouly by removing aluminum but initial heat of adsorption, showed a maximum point and a minimum point. The maximum point would be explained by the improvement of site efficiency due to the enlarged pores. The minimum point could be said by the change of surface property due to the erosed surface of the crystals which revealed new strong adsorption sites.

In this paper, an algorithmic-evolutionary synthesis procedure for retrofitting heat exchanger networks is proposed. It consists of two stages. First, after the amount of maximum energy recovery(MER) is computed, a grass-root network featuring minimum number of units(MNU) is synthesized. In this stage, a systematic procedure of synthesizing MNU networks is presented. It is based upon the concept of pinch, from which networks are synthesized in a logical way by the heuristics verified by the pinch technology. In the second stage, since an initial feasible network is synthesized based on the pre-analysis result of MER and must-matches, an assignment problem between new and existing units is first solved to minimize total required additional areas. After the existing units are assigned, the network can be improved by switching some units and splitting streams. For this purpose, improvement problems are formulated and solved to utilize the areas of existing units as much as possible. A couple of examples are used to demonstrate the effectiveness of the proposed method.

Lanthanum fluoride thin films were prepared by rf-magnetron sputtering method in argon gas and their crystal structures and oxygen sensing properties were investigated. The thin film of was used as a ion conducting solid electrolyte and the sensing electrode was made of platinum black. The film co-sputtered by rf-magnetron sputtering in argon was used as a reference electrode. The structure of was found to be microcrystalline according to the electron diffraction analysis. The potential of sensing electrode relative to that of reference electrode was changed logarithmically by dissolved oxygen concentration in distilled water and its sensing mechanism was based on the electrode reaction of one electron transfer.

NO decomposition and NO reduction by CO on perovskite catalyst have been studied using the technique of thermal desorption spectrometry(TDS) under ultrahigh vacuum(UHV) condition at the adsorption temperature of 300K. About 70% of NO adsorbed molecularly on ion, and the others adsorbed dissociatively on oxygen vacancy and formed various surface complexes. A part of NO adsorbed on showed maximum desorption rate at 450K, and the others decomposed to form . Pre-adsorbed CO gave little effect on NO dissociation, but in the case of pre-adsorption of NO, the post-dosed CO promoted both the dissociation of NO and the formation of . The post-dosed reacted with NO adsorbed on and desorbed as resulting in the enhancement of NO dissociation. And the post-dosed , which adsorbed on the oxygen of the complex, also promoted the formation of by desorbing as .

Hydrogen mordenite and the modified mordenites of different silica/alumina ratio were impregnated by cupric and/or chromic salts, and redox-treated with hydrogen/oxygen at and , respectively and used for catalytic decomposition of NO. Activity of NO decomposition increases with contents of copper and shows maximum at 10wt%. Catalytic activities for the samples treated in are lower than that in . But the increase of silica/alumina by aluminum extraction and chromic addition to cupric salt for the impregnation improved the thermal crystal stability of mordenite which results in stabilized catalytic activity even for the samples pretreated at .

A few basic models have been suggested to simulate the film growth contour in narrow deep trench by low pressure chemical vapor deposition(LPCVD). Among them, the arrival-angle model assumes that the film growth rate depends on the collision frequency of reactant molecules with the substrate surface, and Knudsen-diffusion model assumes that the reactant diffuse into the trench volume by the Knudsen-diffusion mechanism. A third model combines the algorithm of the above two models in the computation process. For demonstration, these models have been applied for simulation of tungsten film deposition and the follow-ing results are obtained. The step coverage is poor when the aspect ratio of trench increases, but is improved when the ratio decreases and the process temperature and pressure increase. The step coverage by tungsten film is improved when the trench is slightly tapered on both sides.

When an initially quiescent, horizontal porous layer saturated with fluid experiences uniform heating from below, the time of the onset of natural convection in time-dependent, nonlinear temperature fields is predicted theoretically. The stability analysis is conducted on the basis of the propagation theory in which the thermal penetration depth is used as a length scaling factor under linear theory with the principle of exchange of stabilities. The solution for disturbance equations of similar transform considering time-de-pendent variations of disturbances is obtained numerically. The resulting correlations of the critical time to mark the onset of regular cells are derived as a function of the Rayleigh number, Prandtl number, and Darcy number. It is seen that natural convection sets in later as the Prandtl number and the Darcy number become smaller.

Activity coefficient of NaCl in NaCl-KCl-Methanol-Water System was measured at up to the total electrolyte concentration of 1mol/kg using ion selective electrodes. The maximum error expected was 5% and the experimental results showed close agreements with published data at low concentrations. Also calculated results by Kim and Lee's thermodynamic mode[1] agreed with the experimental data within 2% error.

The properties of carbon solid prepared from semi-coke powder without using a binder were examined on both the moulding pressures and the calcining temperatures. Up to , the pressure effect on the carbon solid changed characteristically high. The highest compressive strength was obtained on carbon solid calcined at , and its density was .