How to substitute character value into byte type variable in function?

Hi I'm programming arudino lcd.
I make print custom char program. Here it is.

#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

int cmd = 0;

byte a_1[8] = {
  B00000,
  B00000,
  B00000,
  B00000,
  B00000,
  B00000,
  B00000,
};

byte a_2[8] = {
  B00000,
  B10001,
  B00000,
  B00000,
  B10001,
  B01110,
  B00000,
};

void korean(int i)
{
  if(i==1)
  {
  byte a_1[8] = {
  B10101,
  B11101,
  B10101,
  B11101,
  B00000,
  B01110,
  B01110,
                  };
  cmd = 1;
  }
  else
  {
  byte a_1[8] = {
  B00000,
  B00000,
  B00000,
  B00000,
  B00000,
  B00000,
  B00000,
                  };
  }
}

void setup() {
  Serial.begin(115200);
  korean(1);
      lcd.createChar(0, a_1);
  lcd.begin(16, 2);  
  lcd.write(byte(0));
}

void loop() {
}

I want to substitute byte type Variable in function. But it can't.
How to substitute character value into byte type variable in function?

I want to substitute byte type Variable in function. But it can't.

Let's start with which function? You can change the VALUES in the array. You can't create a whole new array and make it take the place of another array.