Schools have spent huge amounts of money installing surveillance cameras in recent years to prevent violence and other crimes, but many have been deemed ineffective, a recent inspection reveals.

Of the 17,471 CCTV cameras inspected in Seoul, Incheon, Gangwon Province and Jeju last year by the Board of Audit and Inspection, some 18.6 percent were found to be improperly installed or blocked by obstacles. Cameras at 161 sites were without infrared devices, making them ineffective at night, and a whopping 96.8 percent, or 16,922 cameras, had resolutions below 500,000 pixels -- the standard level for recognizing faces or other details.

According to the Ministry of Education, Science and Technology, some 101,177 CCTV cameras were installed in school zones and nearby areas as of September last year, accounting for 97.5 percent of 1,707 schools nationwide.

The government merely provide guidelines for installation without mandatory requirements. "Based on the findings of the board, we're looking at ways to improve, such as by eliminating blind spots," a ministry official said.