Alcohol

No one can't can deny the fact that it is very important to drink the importance of drinking since because drinking is a part of doing business or making a business relationship in Korea.

No one can't deny is equivalent to saying, everyone can deny the fact that....

Drinking is also important when you get along fine for bonding with friends, co-workers and relatives.

In the month of December and January, when Koreans throw an end of the year party or a new year party, non-residential district, especially where there a lot of pubs, are usually crowded with many people, like a den infested with an awful lot of vermin.

It shows us not only how important drinking alcohol is in Korea, but also how engrossed alcohol is in this country this country is with alcohol.

If people drinks drink too much alcohol at only one drinking party, they would lose some of their consciousness (=inhibition) and can't decide what is wrong and right when they try to do something.

people, so plural verb. drinks is a singular verb.
Example
people drink to much alcohol.
she/he/<name> drinks too much alcohol.
They drink too much alcohol.

What makes this problem more serious alarming is that heavily heavy drinking is a huge risk not only for drinkers but also non-drinkers, which shouldn't be a victim of drinking heavily.

Heavy drinkers harm themselves, as we know very well, but there's also it's also possible for them to harm other people by causing accidents, because since heavy drinkers don't know how to control themselves, either mentally or physically. (both mentally and physically.)

i think both mentally and physically is a much more appropriate statement but still what you said was right.

They would lead the innocent innocents to a permanent disaster.

I remember the news that about Nickhun, one of the members of Korean idol boyband group 2PM, who was booked for DUI situation a few days ago.

Fortunately, there were no casualty at the scene because the accident was just a form of fender-bender, but nonetheless he have has been bombarded with a bunch of criticism made by netizens infuriated about his reckless behavior.

what is netizens? do you mean citizens?

Look around. Look at the road a road.

How do you feel if the cars on the road can be kind of turn out to be deadly weapons because some of them the drivers were heavily drunk heavily before they grab the wheel of their cars?

You may kiss and bid goodbye with your alive friends alive but regardless of your will, in the blink of an eye..

However, although too much alcohol can lead to terrible accidents, on the contrary it can also be helpful healthy for your body if you drink alcohol in moderation.

Some studies show that alcohol help people relive stresses and maintain their stay in good shape.

You can't avoid drinking because drinking is a culture absorbed in every part of Korea.

Banning alcohol is an impractical idea.

It's totally impossible, and ridiculous idea, and will only draw fierce resistance from people.

No one can deny the fact that drinking is important in Korea, especially because drinking is a part of doing business and forging business relationships.

In other words, it is not an exaggeration to say that most of the relationships between people are revolve around drinking with others.

In the months of December and January, when Koreans throw an end-of-the-year party or a New Year's party, non-residential districts—especially where there are a lot of pubs—are usually crowded with many people, like a den infested with an awful lot of vermin.

You should use hyphens for "end-of-the-year" since you're using it as an adjective. If you say "...when Koreans throw a party at the end of the year", you don't need to use hyphens. ^__^

Since this sentence is quite long, I would use parenthesis or dashes as seen above. This can help separate your extra description about non-residential districts from your main thoughts. Or you could split this sentence in two to make it flow better.

The word "infested" already has a negative connotation and explains that the den is full of vermin. "... an awful lot" is repetitive, so it's not really necessary here.

This shows us not only how important drinking alcohol is in Korea, but also how ingrained the drinking culture is in this country.

"It" is too vague to start the sentence with. "This" is better understood as a reference to the preceding sentence.

Also, "engrossed" sounds a little bit awkward (to me). Are you trying to say that alcohol is very common/popular in Korea? Instead, maybe you want to describe how drinking is deeply rooted in Korean culture and history.

However, drinking alcohol is like the two sides of the same coin.

If people drink too much alcohol at a single drinking party, their consciousness can become impaired, and they won't be able to decide what is wrong or right when they try to do something.

It doesn't make sense to use "would lose" and then "can't decide". The tenses are mixed up.

What makes this problem even more serious is that heavy drinking is a huge risk not only for drinkers but also for non-drinkers, which who shouldn't be victims of drinking heavily.

"Which" can't be used to refer to the non-drinkers; you want to use "who".

They are capable of leading the innocent to a permanent disaster.

"Would" is a little strong, suggesting that heavy drinkers WILL cause harm to innocent people, which is not always true. Instead, heavy drinkers who lose control of themselves are capable of, or are able to, cause great harm. It doesn't mean they always will, though.

I remember the news that Nickhun, one of the members of Korean idol boy band group 2PM, was booked for a DUI a few days ago.

You may want to use a transition word before bringing up the news about Nickhun. "Recently in the news I read that Nickhun..." or "I even recall the news that Nickhun..." so that it connects to your previous sentence.

When he was caught by police officers and tested at the scene by police, he had a blood alcohol concentration of 0.056 percent—over the 0.05 limit in Korea.

Since you already mention that Nickhun is "caught by police officers", there is no need to mention that testing was done "by police". It's redundant.

Also, if you add an extra sentence or phrase about Korea's allowed blood alcohol limit, it will make "0.056" more significant. It will help emphasize that 0.056% is higher than the allowed limit in Korea.

Fortunately, there were no casualties at the scene because the accident was a simple fender-bender, but Nickhun has nonetheless been bombarded with harsh criticism from netizens infuriated by his reckless behavior.

I agree with the other correcter. "Nonetheless" is the perfect word to add!

Look around on any road...

There must be a lot of cars on that road.

How would you feel if the cars on the road suddenly became a kind of deadly weapon, all because their drivers drank heavily before choosing to get behind the steering wheel?

"Get behind the steering wheel" is a more common phrase for "driving" instead of saying they grabbed the wheel.

You may as well kiss your friends goodbye, because regardless of your will, in the blink of an eye...

"Kiss _____ goodbye" is a common phrase that shows hopelessness and loss. If you kiss something goodbye, it means you're probably not going to see it ever again.

After "in the blink of eye" maybe put something to close the sentence. "Boom!" is probably too cliche... Maybe "in the blink of an eye... disaster can strike" or something to show how fast and devastating a crash can be.

Some studies show that alcohol helps people relive stress and maintain their stay in good shape.

Either "maintain their bodies" or "stay in good shape" work, but not both together. ^^

You can't avoid drinking because drinking culture is diffuse throughout Korea.

But even so, it's best not to get yourself into a dead-drunk state.

To eradicate alcohol-related accidents, people need to be educated about the dangers of alcohol use before becoming inebriated.

However, it's best not to get overly drunk.

"dead drunk" is not really used to describe this state, though it is technically correct.

This sentence doesn't really fit the context above or below. Before you are talking about the importance of drinking, and below you talk about banning alcohol. Being overly drunk doesn't relate to either.

Banning alcohol is impractical idea.

Such a ridiculous proposal would draw fierce resistance from people.

To eradicate the accidents relating to alcohol, people need to know the danger of alcohol before being inebriated.

This sentence is also out of place. I recommend putting the "overly drunk" sentence and this sentence into your conclusion as a separate paragraph. Something like, "Alcohol in Korea is never going to go away. However, despite the merits of alcohol in business and friendship, being overly drunk can be dangerous. People should be educated on the dangers of alcohol abuse so that they can drink responsibly. In such a world we can enjoy alcohol and all the advantages that come with it."