Have there been any attempts to unify North and South Korea after the Korean War? I was reading a post on my front page where someone was saying that kids in SK are often taught to be sympathetic to the people of NK and "dream of unification," and also that political figures will differ in how they believe this could be achieved. Has unification been attempted in the past ~50 years and how have these attempts played out (if any)?
The Korean War was the north's attempt at unification. That's the only real attempt at unification.
From the end of the Korean War until the early 1970's, there was no contact between the north and south. In the late 60's, North Korea waged a series of attacks known as the DMZ conflict, or the Second Korean War. They sent hit squads across the border to lay land mines and ambush patrolling US and Korean soldiers. In one instance, they blew up a US Army barracks; in another, they attacked a supply truck. The violence culminated with the Blue House Raid from January 17 to January 29, 1968, and the capture of the USS Pueblo during that, on January 23, 1968. A year later, North Korea shot down a US EC-121 in the East Sea/Sea of Japan. After that, things quieted down.
The result of this violence was that the UN command under General Bonesteel, USA, tightened control of the DMZ and stepped up their training. Park Chung-hee also built a system of militias and built trust within the country so that when North Korean agents infiltrated the South to indoctrinate a village, local villagers escaped and reported this to the military who responded immediately and killed the infiltrators. The other result, coming from the Blue House raid, was that South Korea began to build their own hit squad to kill Kim Il-sung. It was disbanded when relations began to improve, but check out the "based on a true story movie" Silmido for a good action flick about the situation.
In 1972, the director of the South Korean CIA went to North Korea for secret talks, and his counterpart came to Seoul shortly thereafter. That July, the North-South Joint communique was issued. In it, the two countries agreed to reunification but it said that:
The rest of the communique has concrete steps - the two countries won't defame each other, they won't engage in military provocations, they will cooperate in certain areas, and they'll install a military hotline between the two countries.
Of course, history has shown that both sides have violated this, the North more so than the South. In 1976, North Korean soldiers murdered a couple of US soldiers in the Axe Murder incident. The US soldiers were pruning a tree in the DMZ when the North Koreans attacked. In response, the US sent in three platoons to cut down the tree. At the same time, B-52 bombers from Guam flew over, the USS Midway was off the coast, and South Korean Special Forces escorted them in. The Koreans were supposed to be unarmed, but the Minister of Defense told them, in violation of the armistice agreement, to take automatic weapons and grenades with them. While the weapons remained in the vehicles, they were ready to go at a moments notice. Interestingly sidenote, Moon Jae-in, the current liberal candidate for President in South Korea, was one of the Special Forces soldiers. The son of North Korean refugees, if you ever hear people call him a commie or denigrate him and his support of the South, just know that he was a Special Forces soldier who did his duty during one of the toughest times.
In the 80's, North Korea blew up a South Korean plane and they attempted to assassinate the President (he survived, but members of his cabinet were killed).
South Korea has continued to exercise with the US military, one of the key sticking points for North Korea. Unofficially, South Korea did the same thing that North Korea did, sending hit squads into the North to ambush patrols and to blow up bridges or other buildings, but this was during the 60's in a tit-for-tat exchange and was over by the end of the decade.
Despite all of this, the idea of peaceful reunification was again reiterated during the 2000 summit. Without going into too much detail (20 year rule), check out the First and Second Battle's of Yeonpyeong and you'll see the disconnect between actions and words.