There were 15 minutes between the first air raid alert and the sounding of the all-clear signal.

从第一个空袭警报到警报解除号音其间有15分钟。

The alert level "is now at a higher class" than in 2002, says Air Force Brig. Gen. Jung Jae-bu, commander of the 20th Fighter Wing.

“目前的警戒水平”高于2002年，第20战斗机飞行中队指挥官，空军准将郑在卜(音)表示。

If an alert is not issued when it should be, however, the result can be a mid-air collision.

而如果在必要时未能发出预警，其结果就可能是空中撞机。

Passengers traveling by air face a new security alert. Airport screeners are extra-focused on thermos-type insulated beverage containers.

乘坐飞机旅行的乘客面临新的安全警告。机场扫描仪现在更加注意热水瓶性的保温饮料罐。

It also initiated its first-ever air pollution red alert mechanism.

它还启动了首个空气污染红色预警机制。