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This paper presents 10 kW grid connected photovoltaic inverter with high frequency transformer. This inverter system consist of DC/DC Converters, 2 high frequency transformers in parallel, diode full bridge rectifiers and 3 phase inverter. Proto Type inverter is manufactured and experimented. High frequency link DC-DC converter increases input DC voltage and supplies power to the inverter, which can energize directly the grid without LF step-up transformer. This system is lighter, more efficient and economical than the inverter with utility frequency transformer.

This paper presents development of 200 kW grid connected PV inverter. 200 kW Grid connected PV inverter has the utility frequency transformer for the galvanic isolation between DC and AC , and its output is 3-phase 3-wire 60 Hz, 380 V. P&O algorithm is used for the maximum power point tracking (MPPT) and the active frequency drift scheme for the anti islanding protection. The inverter is controlled by 32 bit DSP. This paper explain the performance and test result of utility interface, anti-islanding, efficiency and THD of 200 kW grid connected PV inverter.

This paper presents the operation and performance evaluation of PV-wind hybrid systems installed at Gobi desert area of Mongolia in order to identity the key factors that determines system operation at a severe climate conditions. The installed hybrid systems consist of 5 kW PV, 3 kW wind systems, BOS (balance of systems), data acquisition and transmission equipments. The Naran soum of Sukhbaatar aimag, where main systems are installed, is located on the semi desert area of Mongolia, north 45/spl deg/ 3' east 113/spl deg/ 5' and 700 km away from Ulaanbaatar.

This paper briefly introduces silicon based thin film solar cells: amorphous (a-Si:H), microcrystalline (/spl mu/c-Si:H) single junction and a-Si:H//spl mu/c-Si:H tandem solar cells. The major difference of a-Si:H and /spl mu/c-Si:H cells comes from electro-optical properties of intrinsic Si-films (active layer) that absorb incident photon and generate electron-hole pairs. The a-Si:H film has energy band-gap (Eg) of 1.7-1.8 eV and solar cells incorporating this wide Eg a-Si:H material as active layer commonly give high voltage and low current, when illuminated, compared to /spl mu/c-Si:H solar cells that employ low Eg (1.1 eV) material. This Eg difference of two materials make possible tandem configuration in order to effectively use incident photon energy. The a-Si:H//spl mu/c-Si:H tandem solar cells, therefore, have a great potential for low cost photovoltaic device by its various advantages such as low material cost by thin-film structure on low cost substrate instead of expensive c-Si wafer and high conversion efficiency by tandem structure. In this paper, the structure, process and operation properties of Si-based thin-film solar cells will be discussed.

CuGaSe/sub 2/ absorber layers were grown by evaporating elemental Cu, Ga and Se on molybdenum coated soda lime glass substrates using three-stage process with substrate temperature monitoring. The grain size of the films decreased with the increase of Ga composition, but the morphology of the films improved. The optical band gap of the absorbers is around 1.68 eV regardless of Ga concentration. Using these films the solar cells with a structure SLG/Mo/CuGaSe/sub 2//CdS/ZnO/AI were fabricated. Current-voltage characteristics and spectral response measurements were performed to evaluate device parameters and to analyze loss factors. In optimal condition, the absorber film is 1.9 /spl mu/m thick and slightly Ga rich bulk composition [Cu]/[Ga] =0.88 and we obtained V/sub OC/ = 0.81 V, J/sub SC/ = 11.9 mA, ff =0.635 and /spl eta/ = 6.1 %.

AIn this study, we developed a wearable physiological measurement device (bioshirt). The developed bioshirt can record ECG (lead I, lead II, V1), blood oxygen saturation, 2-axis acceleration, and skin temperature in mobile environment. Sensors are embedded into the bioshirt. It showed noticeable performance in terms of usability and monitoring. Respiration signal is acquired by inductive plethysmograph (IP). However, acquired IP signal is by the upper body movement like arm or abdomen movement. To get correct respiratory signal, we use both IP and EDR (ECG-derived respiration). EDR is used to supplement the IP that is contaminated by some artifact. As result, it provide suitable respiration rate (RR) although IP is contaminated by some noise.

For the objective interpretation of cerebral metabolic patterns in epilepsy patients, we developed a computer-aided classifier using artificial neural network. We studied interictal brain FDG PET scans of 257 epilepsy patients which were diagnosed as normal (n=64), left temporal lobe epilepsy (n=112), or right temporal robe epilepsy (n=81) by visual interpretation. Automatically segmented volumes of interest (VOI) were used to reliably extract the features representing patterns of cerebral metabolism. All images were spatially normalized to MNI standard PET template and smoothed with 16 mm FWHM Gaussian kernel using SPM96. Mean count in cerebral region was normalized. The VOI for 34 cerebral regions were previously defined on the standard template and 17 different counts of mirrored regions to hemispheric midline were extracted from spatially normalized images. A three-layer feedforward error backpropagation neural network classifier with 17 input nodes and 3 output nodes was used. The network was trained to interpret metabolic patterns and produce identical diagnoses with those of expert viewers. The performance of the neural network was optimized by testing with 5/spl sim/40 nodes in hidden layer. Randomly selected 40 images from each group were used to train the network and the remainders were used to test the learned network. The optimized neural network gave a maximum agreement rate of 80.3% with expert viewers. It used 20 hidden nodes and was trained for 1508 epochs. Also, neural network gave agreement rates of 75/spl sim/80% with 10 or 30 nodes in hidden layer. We conclude that artificial neural network performed as well as human experts and could be potentially useful tool as clinical decision supporting tool for the localization of epileptogenic zones.

The effects of SiH/sub 4/ flow and H/sub 2/ dilution on the hot wire silicon films have been studied in this paper. The Si films deposited at low SiH/sub 4/ flow (1 to 7 sccm) have distinct Raman TO mode peak near 520 cm/sup -1/ even at no H/sub 2/ dilution. The microcrystalline to amorphous phase transition, however, occurred at increased SiH/sub 4/ flow above than 10 sccm. The added H/sub 2/ gas does not contribute to the crystallinity improvement of the samples deposited at low SiH/sub 4/ flow while the amorphous films are crystallized as the high H/sub 2/ gases are employed. On the contrary, when the deposition time increased, the crystalline properties are greatly improved; crystalline volume fraction reached up to 75% without H/sub 2/ dilution. The electrical properties and hydrogen bonding configuration as functions of SiH/sub 4/ flow and different dilution conditions are also discussed in the paper.