• 대기
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• 제23권3호
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• pp.331-346
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• 2013

A case study of mesoscale snowfall with polar low signature during 25~26 December 2010 in South Korea is presented. The data used for analysis include surface and upper level weather charts, rain gauge, sea surface temperature, satellite imagery, sounding, and global $1^{\circ}{\times}1^{\circ}$ reanalysis data. The system initiated with a surface trough near the bay of Bohai but quickly intensified to become a polar low within 12 hours. The polar low moved southeastward bringing snowfall to southwestern Korea. There was strong instability layer beneath 800 hPa but baroclinicty was weak and disappeared as the low progressed onto land. Shortwave at 500 hPa and the surface trough became in-phase which hindered the development of the polar low while it approached Korea. However, there were strong tropopause folding (~500 hPa) and high potential vorticity (PV), which allowed the system to maintain its structure and dump 20.3 cm of snow in Jeonju. Synoptic, thermodynamic, dynamic, and moisture analyses reveal that polar low developed in an area of baroclinicity with strong conditional instability and warm air advection at the lower levels. Further, the development of a surface trough to polar low was aided by tropopause folding with PV advection in the upper level, shortwave trough at 500 hPa, and moisture advection with low-level jet (LLJ) of 15 m $s^{-1}$ or more at 850 hPa. Maximum snowfall was concentrated in this region with convection being sustained by latent heat release.

• Journal of Advanced Marine Engineering and Technology
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• 제36권7호
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• pp.876-884
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• 2012

The worldwide CPV(Concentrated Photo Voltaic) market has been increased rapidly due to the increase in large-scale PV(Photo Voltaic) plants which are situated in sun-rich areas with either a Mediterranean or equatorial-type climate. CPV systems are arguably some of the most important devices in the production of electricity within regions with a sun-rich climate, particularly those which benefit from abundant direct solar irradiation. We have developed a 500X CPV module with rated power of 170Wp. The CPV module must satisfy the constraint of having a sensitive tracking accuracy due to the limited tolerance of the acceptance angle in intrinsic optical design. In this study, the module's acceptance angle used was designed with a tolerance angle of ${\pm}1^{\circ}$ in the secondary optics design. In general, non-concentrated module type 2-axis trackers have a tolerance angle larger than ${\pm}1^{\circ}$ due to standard silicon-type modules which are insensitive to the tracking accuracy of the sun. They have a tolerance angle of ${\pm}2{\sim}4^{\circ}$, which fails to exert a significant influence on the performance of the module. This paper provides a study of an experimental variation of the efficiency of the CPV module in terms of its tracking accuracy. Also, the performance of the module is studied from the perspective of temperature and direct irradiation.