Over the past years, many research works have been carried out to investigate the factors which govern the performance of diesel engine. The air pollutant emission from the diesel engine is still a significant environmental concern in many countries. In the present study, new system of smoke reduction of diesel engine is proposed. This new system is using vacuum equipment and STS filter for capture smoke. To confirm new system experiments were performed at engine dynamometer. As a result of this experiment, the smoke reduction ratio of this system was identified high reduction ratio than PDPF. But the power of this system application was measured 10% decrease than base engine performance. There were improvement effects of using STS filter than ceramic filter.

Predation, development, and ovipostion experiments were conducted to evaluate Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) as a potential biological control agent for tomato russet mite, Aculops lycopersici (Massee) (Acari: Eriophyidae) which is a periodic pest of greenhouse tomatoes. Results show that A. swirskii attacked all developmental stages of A. lycopersici, and had a type II functional response on the prey densities given. The predation rates of A. swirskii on A. lycopersici in the presense of alternative food sources such as pollen, thrips first instar, or whitefly eggs were recorded as 74%, 56%, and 76%, respectively of the predation rate on A. lycopersici alone. Amblyseius swirskii successfully completed their life-cycle on either A. lycopersici or cattail pollen. At 25oC, 70% RH, development time of female A. swirskii fed on A. lycopersici or on cattail pollen took 5.0 and 6.2 days, respectively. For the first 10 days after moulting to the adult stage, A. swirskii fed on A. lycopersici had higher daily oviposition rate (2.0 eggs per day) than on pollen (1.5 eggs per day). From this laboratory study, it can be concluded that A. swirskii has promising traits as a predator against A. lycopersici and that their populations can be stably maintained using alternative food such as cattail pollen. We suggest that the effectiveness of A. swirskii against A. lycopersici under field conditions deserves to be investigated.

We present a progress report on HCN(1-0) line observations toward starless cores to probe inward motions. We have made a single pointing survey toward the central regions of 85 starless cores and performed mapping observations of 6 infall candidate starless cores. The distributions of the velocity difference between HCN(1-0) hyperfine lines and the optically thin tracer N2H+(1-0) are significantly skewed to the blue, meaning that HCN(1-0) frequently detects inward motions. Their skewness to the blue is even greater than that of CS(2-1) Lee et al., possibly implying more infall occurrence than CS(1-0). We identify 19 infall candidates by using several characteristics illustrating spectral infall asymmetry seen in HCN(1-0) hyperfine lines, CS(3-2), CS(2-1), DCO+(2-1) and N2H+ observations. The HCN(1-0) F(O-l) with the least optical depth usually shows a similar intensity distribution to that of N2H+ which closely traces the density distribution of the cores, indicating that HCN(1-0) is less chemically affected and so believed to reflect kinematics occurring in rather inner regions of the cores. Detailed radiative transfer model fits of the spectra are underway to analyze central infall kinematics in starless cores.