diff --git a/.gitignore b/.gitignore
index c18dd8d..c8ab231 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
 __pycache__/
+log/
+.vs/
diff --git a/data_checker.py b/data_checker.py
index 2b353fd..946787e 100644
--- a/data_checker.py
+++ b/data_checker.py
@@ -1,3 +1,4 @@
+import datetime
 import transaction
 
 
@@ -50,10 +51,14 @@ class DataChecker:
 		buy_or_sell = False
 		if self.condition_cnt >= self.condition_limit:
 			buy_or_sell = True
-			self.type = 'ask' if self.type == 'bid' else 'ask'
+			self.type = 'ask' if self.type == 'bid' else 'bid'
 			self.condition_cnt = 0
 			self.condition_limit = Config.INITIAL_LIMIT
 
-		print('{} {:.2f} {:.2f} {:.2f} {} ({}) {}'.format(tr, avg, sd, self.condition_limit, self.condition_cnt, self.type, 'action!' if buy_or_sell else ''))
+			today = datetime.datetime.now().strftime('%Y-%m-%d')
+			with open('log/trade-{}.txt'.format(today), 'a') as the_file:
+				the_file.write('{} {:.2f} {:.2f} {:.2f} {} ({}) {}\n'.format(tr, avg, sd, self.condition_limit, self.condition_cnt, self.type, 'action!' if buy_or_sell else ''))
+
+		print('{} {} {:.2f} {:.2f} {:.2f} {} ({}) {}'.format(tr.key, tr, avg, sd, self.condition_limit, self.condition_cnt, self.type, 'action!' if buy_or_sell else ''))
 
 		
diff --git a/data_manager.py b/data_manager.py
index 9a8020e..ebe99c7 100644
--- a/data_manager.py
+++ b/data_manager.py
@@ -1,19 +1,36 @@
+import datetime
+
 import transaction
 import data_checker
 
 
 class DataMgr:
+
+	TR_MAX_CNT = 500
+	TR_MAINTAIN_CNT = 100
+
 	def __init__(self):
-		self.transactions = {}
+		self.transactions = []
 		self.data_checker = data_checker.DataChecker()
 
+	def contains(self, tr: transaction.Transaction):
+		next_item = next((i for i, x in enumerate(self.transactions) if x.key == tr.key), None)
+		return (next_item is not None)
+
 	def insert(self, item):
-		transactions_new = {}
 		tr = transaction.Transaction(item)
-		if tr.time in self.transactions:
+		if self.contains(tr):
 			return False
 
 		self.data_checker.add(tr)
-		self.transactions[tr.time] = tr
+		self.transactions.append(tr)
+
+		if len(self.transactions) >= DataMgr.TR_MAX_CNT:
+			today = datetime.datetime.now().strftime('%Y-%m-%d')
+			with open('log/log-{}.txt'.format(today), 'a') as log_file:
+				for key in self.transactions[:-DataMgr.TR_MAINTAIN_CNT]:
+					log_file.write('{}\n'.format(self.transactions[key]))
+
+			self.transactions = self.transactions[-DataMgr.TR_MAINTAIN_CNT:]
 
 		return True
diff --git a/main.py b/main.py
index 000bcc4..acd6bdd 100644
--- a/main.py
+++ b/main.py
@@ -1,3 +1,5 @@
+import os
+
 from xcoin_api_client import *
 import sched
 import time
@@ -32,6 +34,9 @@ rgParams = {
 scheduler = sched.scheduler(time.time, time.sleep)
 timer_delay = 0.1
 
+if not os.path.exists('log'):
+    os.makedirs('log')
+
 def printTicker(result):
 	print("["+time.strftime("%H:%M:%S")+"]" + " status: " + result["status"] + " last: " + result["data"]["closing_price"])
 
@@ -40,6 +45,8 @@ def printTransaction(result):
 	for item in result['data']:
 		print('\t[' + item['transaction_date']+']' + item['type'] + ' ' + item['price']);
 
+def printTransactionItem(item):
+	print('{}'.format(item))
 
 datamgr = data_manager.DataMgr()
 def main(arg):
@@ -49,6 +56,10 @@ def main(arg):
 
 	result = api.xcoinApiCall("/public/recent_transactions/" + rgParams["order_currency"], rgParams)
 	if result is not None:
+		#for item in reversed(result['data']):
+		#	printTransactionItem(item)
+		#print('--------------')
+
 		for item in reversed(result['data']):
 			datamgr.insert(item)
 
diff --git a/transaction.py b/transaction.py
index a4c3ffe..4fcd5fa 100644
--- a/transaction.py
+++ b/transaction.py
@@ -2,6 +2,7 @@
 
 class Transaction:
 	def __init__(self):
+		self.key = None
 		self.time = None
 		self.price = None
 		self.unit = 0
@@ -13,5 +14,7 @@ class Transaction:
 		self.unit = float(item['units_traded'])
 		self.type = item['type']
 
+		self.key = self.time + '_' +  str(self.unit)
+
 	def __str__(self, **kwargs):
-		return '[{}] {} {}'.format(self.time, self.type, self.price)
\ No newline at end of file
+		return '[{}] {} {}'.format(self.time, self.type, self.price)