The SV1 service - NAMAS(Navigation Monitoring & Assistance Service) collects ship’s position data in all South Korean waters, and predicts the next positions, calculates the CPAs between ships within a certain distance, evaluates basic collision risk and each vulnerability, then integrates to the navigational collision risk. This paper describes the functions and background chosen in the navigation risk solving system; Data characteristics, framework of navigation risk solving system, and data structures and methods for efficient computation for CPA calculations and detecting accident risk situations.

Abstract
1. Introduction
2. Data Characteristics for the SV1 Services
    2.1 Location Data for the SV1
    2.2 Static Data for the SV1
3. Framework of Navigation Risk Solving System
    3.1 Changes in Module 1
    3.2 Divide-and-Conquer method for CPA calculation
    3.3 Experiments for AIS position prediction
4. New Approach for CPA calculation and detecting accident risk situations
5. Conclusions
References

• Geonung KIM(Dept. of Computer Engineering, Mokpo National Maritime University) Corresponding Author
• Gyei-Kark PARK(Dept. of Logistics and Maritime Studies, Mokpo National Maritime University)
• Gi-Jeong JO(Korea Institute of Aids to Navigation)