diff --git a/src/models/ocr_model/utils/to_katex.py b/src/models/ocr_model/utils/to_katex.py
index e7295bf..b6166dc 100644
--- a/src/models/ocr_model/utils/to_katex.py
+++ b/src/models/ocr_model/utils/to_katex.py
@@ -54,16 +54,58 @@ def change(input_str, old_inst, new_inst, old_surr_l, old_surr_r, new_surr_l, ne
             result += input_str[i:start]
             i = start
     
-    if old_inst != new_inst and old_inst in result:
+    if old_inst != new_inst and (old_inst + old_surr_l) in result:
         return change(result, old_inst, new_inst, old_surr_l, old_surr_r, new_surr_l, new_surr_r)
     else:
         return result
 
 
+def find_substring_positions(string, substring):
+    positions = [match.start() for match in re.finditer(re.escape(substring), string)]
+    return positions
+
+
+def rm_dollar_surr(content):
+    pattern = re.compile(r'\\[a-zA-Z]+\$.*?\$|\$.*?\$')
+    matches = pattern.findall(content)
+    
+    for match in matches:
+        if not re.match(r'\\[a-zA-Z]+', match):
+            new_match = match.strip('$')
+            content = content.replace(match, ' ' + new_match + ' ')
+    
+    return content
+
+
+def change_all(input_str, old_inst, new_inst, old_surr_l, old_surr_r, new_surr_l, new_surr_r):
+    pos = find_substring_positions(input_str, old_inst + old_surr_l)
+    res = list(input_str)
+    for p in pos[::-1]:
+        res[p:] = list(change(''.join(res[p:]), old_inst, new_inst, old_surr_l, old_surr_r, new_surr_l, new_surr_r))
+    res = ''.join(res)
+    return res
+
+
 def to_katex(formula: str) -> str:
     res = formula
-    res = change(res, r'\mbox ', r'', r'{', r'}', r'', r'')
-    res = change(res, r'\mbox', r'', r'{', r'}', r'', r'')
+    # remove mbox surrounding
+    res = change_all(res, r'\mbox ', r' ', r'{', r'}', r'', r'')
+    res = change_all(res, r'\mbox', r' ', r'{', r'}', r'', r'')
+    # remove hbox surrounding
+    res = re.sub(r'\\hbox to ?-? ?\d+\.\d+(pt)?\{', r'\\hbox{', res)
+    res = change_all(res, r'\hbox', r' ', r'{', r'}', r'', r' ')
+    # remove raise surrounding
+    res = re.sub(r'\\raise ?-? ?\d+\.\d+(pt)?', r' ', res)
+    # remove makebox
+    res = re.sub(r'\\makebox ?\[\d+\.\d+(pt)?\]\{', r'\\makebox{', res)
+    res = change_all(res, r'\makebox', r' ', r'{', r'}', r'', r' ')
+    # remove vbox surrounding, scalebox surrounding
+    res = re.sub(r'\\raisebox\{-? ?\d+\.\d+(pt)?\}\{', r'\\raisebox{', res)
+    res = re.sub(r'\\scalebox\{-? ?\d+\.\d+(pt)?\}\{', r'\\scalebox{', res)
+    res = change_all(res, r'\scalebox', r' ', r'{', r'}', r'', r' ')
+    res = change_all(res, r'\raisebox', r' ', r'{', r'}', r'', r' ')
+    res = change_all(res, r'\vbox', r' ', r'{', r'}', r'', r' ')
+
 
     origin_instructions = [
         r'\Huge',
@@ -77,10 +119,14 @@ def to_katex(formula: str) -> str:
         r'\tiny'
     ]
     for (old_ins, new_ins) in zip(origin_instructions, origin_instructions):
-        res = change(res, old_ins, new_ins, r'$', r'$', '{', '}')
-    res = change(res, r'\boldmath ', r'\bm', r'$', r'$', r'{', r'}')
-    res = change(res, r'\boldmath', r'\bm', r'$', r'$', r'{', r'}')
-    res = change(res, r'\scriptsize', r'\scriptsize', r'$', r'$', r'{', r'}')
+        res = change_all(res, old_ins, new_ins, r'$', r'$', '{', '}')
+    res = change_all(res, r'\boldmath ', r'\bm', r'{', r'}', r'{', r'}')
+    res = change_all(res, r'\boldmath', r'\bm', r'{', r'}', r'{', r'}')
+    res = change_all(res, r'\boldmath ', r'\bm', r'$', r'$', r'{', r'}')
+    res = change_all(res, r'\boldmath', r'\bm', r'$', r'$', r'{', r'}')
+    res = change_all(res, r'\scriptsize', r'\scriptsize', r'$', r'$', r'{', r'}')
+    res = change_all(res, r'\emph', r'\textit', r'{', r'}', r'{', r'}')
+    res = change_all(res, r'\emph ', r'\textit', r'{', r'}', r'{', r'}')
     
     origin_instructions = [
         r'\left',
@@ -104,10 +150,31 @@ def to_katex(formula: str) -> str:
         r'\Biggr'
     ]
     for origin_ins in origin_instructions:
-        res = change(res, origin_ins, origin_ins, r'{', r'}', r'', r'')
+        res = change_all(res, origin_ins, origin_ins, r'{', r'}', r'', r'')
 
     res = re.sub(r'\\\[(.*?)\\\]', r'\1\\newline', res)
 
     if res.endswith(r'\newline'):
         res = res[:-8]
-    return res
+
+    # remove multiple spaces
+    res = re.sub(r'(\\,){1,}', ' ', res)
+    res = re.sub(r'(\\!){1,}', ' ', res)
+    res = re.sub(r'(\\;){1,}', ' ', res)
+    res = re.sub(r'(\\:){1,}', ' ', res)
+    res = re.sub(r'\\vspace\{.*?}', '', res)
+
+    # merge consecutive text
+    def merge_texts(match):
+        texts = match.group(0)
+        merged_content = ''.join(re.findall(r'\\text\{([^}]*)\}', texts))
+        return f'\\text{{{merged_content}}}'
+    res = re.sub(r'(\\text\{[^}]*\}\s*){2,}', merge_texts, res)
+
+    res = res.replace(r'\bf ', '')
+    res = rm_dollar_surr(res)
+
+    # remove extra spaces (keeping only one)
+    res = re.sub(r' +', ' ', res)
+
+    return res.strip()