This paper discusses two main methodologies of sizing photovoltaic installations and provides a comparative analysis in terms of the accuracy and feasibility of these two methodlogies. One of these two methodoligies is a simplified approach requiring very little data and information an dis based on some assumptions. The other, the loss-of-load probability method is statistically based ; it ismuch more elaborate and requires complex set of data. Our study shows that for a moderate PV installation to provide basic electrical needs of a small to medium-size detached family house, the simplified method is well suited for such conditions.

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In order to study cognitive function rhythms related to auditory frequency systems for people who prefer to be active at night, we conducted experiments during early evening (17:00) and after midnight (01:00) sessions. On the basis of a morningness/eveningness questionnaire, seven moderately evening-type subjects (E-types) were selected. Diurnal changes of human cognitive function under 250/500 Hz and 1000/2000 Hz conditions were assessed by auditory event-related brain potential using an oddball task. The subjects were asked to press a button when the target stimulus was detected, but to do nothing when the standard stimulus was detected. Significant diurnal changes of P300 latency and P300 amplitude were observed. The P300 latency at 17:00 was significantly shorter than at 01:00 at the Fz electrode site under the high-frequency condition [F(1,6)=6.335, P<0.05]. The P300 amplitude at 17:00 was significantly greater than at 01:00 [F(1,6)=159.964, P<0.0001]. The P300 amplitude obtained after the high-frequency stimulus was significantly smaller than that after the low-frequency stimulus at 01:00 [F(1,6)=6.258, P<0.05], but not at 17:00. These results revealed that stimulus frequency had effects on human cognitive function, and E-types' cognitive function decreased at midnight compared to that in the early evening. This study had extended previous findings of auditory P300 studies on diurnal variations in terms of time of day and stimulus parameter.

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The effects of swimming exercise on immune function of growing rats fed a high-fat diet were studied. Thirty-four male rats were randomly divided into 4 groups: CS (control diet sedentary group, n=8), CE (control diet exercised group, n=9), HS (high-fat diet sedentary group, n=8) and HE (high-fat diet exercised group, n=9). The high-fat diet was included 35% carbohydrate, 20% protein and 35% fat. AIN-76 was used as the control diet. In the exercised groups, the rats swam for 60 min day⁻¹, 5 days/week for 4 weeks. Mean blood glucose, total cholesterol, and triglyceride levels were not significantly different between groups, and neither were mean soleus muscle mitochondrial citrate synthase activities. However, the CD4+/CD8+ ratio (p<0.05) and the glycogen content of the plantarius muscle were significantly lower in the HS group than in the CS group. The CD4+ T cell population of the spleen and the glycogen content of the plantarius muscle were significantly higher in the HE group than in the HS group (p<0.01 and p<0.05 respectively). Interleukin-2 production following 5 µg/ml of conconavalin A (Con. A) stimulation tended to be higher in the HE group than in the other groups but the difference was not statistically significant. It is suggested that regular endurance exercise in growing rats fed a high-fat diet increases the CD4+ T cell subpopulation by stimulating interleukin-2 production.

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This study was performed to investigate the effect of regular aerobic exercise on the representative markers of cardiovascular inflammatory diseases. Biomarkers of cardiovascular disease were measured in 89 healthy elderly males (age range; 47–88) living in Seoul, Korea. Questionnaires were used to assess the status of the regular exercise participants. Various factors associated with chronic cardiovascular diseases, including total cholesterol, triglyceride, phospholipid, platelet, and C-reactive protein were lowered in regular exercise participants (p<0.05). In contrast, serum albumin concentration was higher in the exercised group compared with a non-exercised group (p<0.05). Therefore it was concluded that participation in regular exercise reduces cardiovascular inflammation and offers protection against chronic cardiovascular disease in elderly Korean men.

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Tail suspension is a ground-based model for the microgravity and cephalic fluid-shift aspects of spaceflight. To evaluate osteopenia and bone metabolism induced by microgravity, 18 8-week-old female Spraque-Dawley (SD) rats completed tail suspension for 2-weeks (n=6, TS), and were compared with baseline controls (n=6, BC) and 2-week vivarium control rats (n=6, VC). The BC, VC, and TS groups were fed standard lab chow (CRF-1, Charles River, Japan) and water ad libitum while control animals (BC and VC) were pair fed with the appropriate TS group to control for caloric intake. After 2-week suspension, the rats were sacrificed and femurs were removed for analysis of bone mineral density (BMD) by dual energy X-ray absorptionmetry (DEXA, Lunar DPXL, USA) and peripheral quantitative computed tomography (pQCT, XC-960, Germany). The femoral fresh weight of the TS group was approximately 8% lower when compared with the VC group (p<0.05), but the femoral length showed no change between the VC and the TS group. On the other hand, BMD and cortical BMD of femur in the VC group were increased by approximately 16% and 4% when compared with those of the BC group (p<0.001), but those of the TS group did not increase, and were approximately 11% and 4% lower than those of the VC (p<0.01). Similarly, the cortical cross-sectional area, bone thickness, and stress-strain index (SSI), which reflect the mechanical strength of cortical bone in the VC group increased significantly (p<0.01, respectively), but those of the TS group were significantly lower than those of the VC group (p<0.01 or p<0.001). However, trabecular BMD did not show a significant difference between any groups. The serum calcium (Ca) concentration, urinary Ca, and urinary deoxypyridinoline (Dpd) excretions of the VC and the TS groups showed similar levels. However, urinary phosphate (P) excretion of the TS group dynamically decreased, being approximately 50% lower than that of the VC group (p<0.05), while serum P concentration increased (p<0.001). These results suggest that exposure to a microgravity environment induces spontaneous osteopenia in mainly cortical bone, and this osteopenia might be caused by disturbed P homeostasis.

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