Forbush Decreases (FD) are transient, sudden reductions of cosmic ray (CR) intensity lasting a few days, to a week. Such events are observed globally using ground neutron monitors (NMs). Most studies of FD events indicate that an FD event is observed simultaneously at NM stations located all over the Earth. However, using statistical analysis, previous researchers verified that while FD events could occur simultaneously, in some cases, FD events could occur non-simultaneously. Previous studies confirmed the statistical reality of non-simultaneous FD events and the mechanism by which they occur, using data from high-latitude and middle-latitude NM stations. In this study, we used long-term data (1971-2006) from middle-latitude NM stations (Irkutsk, Climax, and Jungfraujoch) to enhance statistical reliability. According to the results from this analysis, the variation of cosmic ray intensity during the main phase, is larger (statistically significant) for simultaneous FD events, than for non-simultaneous ones. Moreover, the distribution of main-phase-onset time shows differences that are statistically significant. While the onset times for the simultaneous FDs are distributed evenly over 24- hour intervals (day and night), those of non-simultaneous FDs are mostly distributed over 12-hour intervals, in daytime. Thus, the existence of the two kinds of FD events, according to differences in their statistical properties, were verified based on data from middle-latitude NM stations.

Recently, two instruments of cosmic ray are operating in South Korea. One is Seoul muon detector after October 1999 and the other is Daejeon neutron monitor (Kang et al. 2012) after October 2011. The former consists of four small plastic scintillators and the latter is the standard 18 NM 64 type. In this report, we introduce the characteristics of both instruments. We also analyze the flux variations of cosmic ray such as diurnal variation and Forbush decrease. As the result, the muon flux shows the typical seasonal and diurnal variations. The neutron flux also shows the diurnal variation. The phase which shows the maximum flux in the diurnal variation is around 13-14 local time. We found a Forbush decrease on 7 March 2012 by both instruments. It is also identified by Nagoya multi-direction muon telescope and Oulu neutron monitor. The observation of cosmic ray at Jangbogo station as well as in Korean peninsula can support the important information on space weather in local area. It can also enhance the status of Korea in the international community of cosmic ray experiments.

In order to better understand the biological systems that are affected in response to cosmic ray, we conducted the weighted gene co-expression network analysis with module detection method. By using the Pearson’s correlation coefficient value, we were evaluated the complex gene-gene functional interactions between 680 CR-response probes from integrated microarray datasets, which included large-scale transcriptional profiling of 918 microarray samples. These probes were divided into 6 distinct modules that contained 20 enriched function such as oxidoreductase activity, response to stimulus and stress, and hydrolase activity. Especially, module 1 and 2 commonly showed the enriched annotation categories such as oxidoreductase activity, including the enriched cis-regulatory elements known as ROS specific regulator. These results suggest in module1 and 2 that ROS-mediated irradiation response pathway are affected by CR. We found the 243 irradiation-dependent probes, which were exhibited the similarities of differentially expressed patterns in various irradiation microarray datasets, and RT-PCR for confirmations of several irradiation-dependent genes were exhibited the similar expressed patterns in rice by CR, gamma ray and Ion beam treatments. Interestingly, these genes were differentially expressed by non-gravity. Moreover, we were identified the co-regulations between several irradiation-dependent genes and functional interacted genes in the CR-responsive network by various GA treatments such as different conditions of dose and treatment time. These results of network-based analysis might provide a clue to understanding the complex biological system of CR.