This is the 3463rd most frequent Korean word.
때에는
"때에는" means "when it is (a certain time or situation)."
In this sentence, '때에는' is used to specify the particular occurrence of waking up when the subsequent action (stretching) happens or is required.
저는 아침에 일어날 때에는 스트레칭을 해요.
When I wake up in the morning, I do stretching.
Here, '때에는' emphasizes the condition or context within which certain behavior (keeping etiquette) is expected or applicable during meals.
식사를 할 때에는 예절을 지켜야 합니다.
When having a meal, one must maintain etiquette.
In this instance, '때에는' is utilized to indicate the conditional occurrence (raining) that prompts or necessitates the action that follows (bringing an umbrella).