A. K-pop Ranks the First Everywhere

B. YouTube Helps Korean Cultures Spread

C. Hallyu Makes Waves across the World

D. Korean Soap Operas Are Growing in Popularity

D

The biggest danger facing airlines nowadays may not be a terrorist with a gun, but the man with portable computer in business class. In the last 16 years, pilots have reported well over 100 incidents that could have been caused by electromagnetic interference （电磁干扰）. The source of this interference remains not proved, but increasingly, experts are pointing the blame at portable electronic devices such as portable computers, radio and cassette players and mobile telephones.

RTC.A, an organization which advises the aviation （航空）industry, has suggested that all airlines ban such devices from being used during "critical" stages of flight particularly take-off and landing. Some experts have gone further, calling for a total ban during all flights.Currently, rules on using these devices are left up to individual airlines. And although some airlines prevent passengers from using such equipment during take-off and landing, most are unwilling to carry out a total ban, given that many passengers want to work during flight.

The difficulty is predicting how electromagnetic fields might affect an aircraft's computers. Experts know that portable devices send out radiation which affects those wavelengths which aircraft use for navigation and communication. But, because they have not been able to reproduce these effects in a laboratory. they have no way of knowing whether the interference might be. dangerous or not.