Crimes with explosives is one of the mass-destructive crimes that involves the most victims. It is heavily punished under the Korean laws. Mid-eastern area is one of the leading places that are home to improvised explosive device attacks, in the form of religious or political terrorism because of its convenience of use, production and disguise. Improvised bombs are permeating into domestic crimes in Korea as their tools. Use of explosive substances are strictly restricted in this country, but it is not impossible to find its information online and to create private explosives with a bit of interest. And they are being traded in the grey market. For this reason, this thesis offers the method of an efficient safety control of explosive substances, which can be used as raw materials for improvised explosive devices, in order to protect citizens’lives and properties and to promote national security down the road.

As Crosby notes, the most companies spend 15 to 20% of their sales dollars on quality costs. Generally the most effective way to manage quality costs is to avoid having defects in the first place. In this paper we have studied about the repair(service) problem of domestic gas boiler within warranty period. We develop a system, which man could find the cause of the problem at an early stage and could devise a countermove to the problem under supposing that the service(repair) rate follows exponential distribution and the product is manufactured lot-for-lot continually. Using the developed early sensing system. it is expected to improve the reliability of the product, to save expenses of company and to improve customer’s satisfaction. And the system will be expended to incorporate information technology, which can detect the repair rate automatically.