diff --git a/Foundation/org.egovframe.rte.fdl.filehandling/src/main/java/org/egovframe/rte/fdl/filehandling/EgovFileUtil.java b/Foundation/org.egovframe.rte.fdl.filehandling/src/main/java/org/egovframe/rte/fdl/filehandling/EgovFileUtil.java
index 633a3fa7..ad16c1c9 100755
--- a/Foundation/org.egovframe.rte.fdl.filehandling/src/main/java/org/egovframe/rte/fdl/filehandling/EgovFileUtil.java
+++ b/Foundation/org.egovframe.rte.fdl.filehandling/src/main/java/org/egovframe/rte/fdl/filehandling/EgovFileUtil.java
@@ -178,7 +178,7 @@ public static String readFileContent(InputStream in) throws IOException {
      * String 영으로 파일의 내용을 읽는다.
      */
     public static String readFile(File file, String encoding) throws IOException {
-        StringBuffer sb = new StringBuffer();
+        StringBuilder sb = new StringBuilder();
         List<String> lines = readTextLines(file, encoding);
 
         for (Iterator<String> it = lines.iterator(); ; ) {
@@ -441,8 +441,8 @@ public List<?> ls(final String[] cmd) throws FileSystemException {
     /**
      * 지정한 위치의 하위 디렉토리 목록을 가져온다.
      */
-    private StringBuffer listChildren(final FileObject dir, final boolean recursive, final String prefix) throws FileSystemException {
-        StringBuffer line = new StringBuffer();
+    private StringBuilder listChildren(final FileObject dir, final boolean recursive, final String prefix) throws FileSystemException {
+        StringBuilder line = new StringBuilder();
         final FileObject[] children = dir.getChildren();
 
         for (final FileObject child : children) {
diff --git a/Foundation/org.egovframe.rte.fdl.idgnr/src/main/java/org/egovframe/rte/fdl/idgnr/impl/strategy/EgovIdGnrStrategyImpl.java b/Foundation/org.egovframe.rte.fdl.idgnr/src/main/java/org/egovframe/rte/fdl/idgnr/impl/strategy/EgovIdGnrStrategyImpl.java
index 73602e86..46c81005 100755
--- a/Foundation/org.egovframe.rte.fdl.idgnr/src/main/java/org/egovframe/rte/fdl/idgnr/impl/strategy/EgovIdGnrStrategyImpl.java
+++ b/Foundation/org.egovframe.rte.fdl.idgnr/src/main/java/org/egovframe/rte/fdl/idgnr/impl/strategy/EgovIdGnrStrategyImpl.java
@@ -78,7 +78,7 @@ public static String fillString(String originalStr, char ch, int cipers) {
         }
 
         int difference = cipers - originalStrLength;
-        StringBuffer strBuf = new StringBuffer();
+        StringBuilder strBuf = new StringBuilder();
         for (int i = 0; i < difference; i++) {
             strBuf.append(ch);
         }
diff --git a/Foundation/org.egovframe.rte.fdl.string/src/main/java/org/egovframe/rte/fdl/string/EgovStringUtil.java b/Foundation/org.egovframe.rte.fdl.string/src/main/java/org/egovframe/rte/fdl/string/EgovStringUtil.java
index d3db1630..31814ff0 100755
--- a/Foundation/org.egovframe.rte.fdl.string/src/main/java/org/egovframe/rte/fdl/string/EgovStringUtil.java
+++ b/Foundation/org.egovframe.rte.fdl.string/src/main/java/org/egovframe/rte/fdl/string/EgovStringUtil.java
@@ -903,7 +903,7 @@ public static String reverse(String str) {
         if (str == null) {
             return null;
         }
-        return new StringBuffer(str).reverse().toString();
+        return new StringBuilder(str).reverse().toString();
     }
 
     /**