diff --git a/ESP32_CAN_Logger.ino b/ESP32_CAN_Logger.ino
index dc39490..ac6740a 100644
--- a/ESP32_CAN_Logger.ino
+++ b/ESP32_CAN_Logger.ino
@@ -10,6 +10,7 @@
 #include <SoftWire.h>
 #include <SD.h>
 #include <WiFi.h>
+#include <esp_wifi.h>
 #include <WebServer.h>
 #include <WebSocketsServer.h>
 #include <freertos/FreeRTOS.h>
@@ -1541,6 +1542,11 @@ void setup() {
     
     // WiFi AP 시작
     WiFi.softAP(wifiSSID, wifiPassword);
+    
+    // WiFi 성능 최적화
+    WiFi.setSleep(false);  // WiFi 절전 모드 비활성화 (신호 강도 개선)
+    esp_wifi_set_max_tx_power(84);  // TX 출력 최대화 (20.5dBm = 84/4)
+    
     Serial.print("✓ AP SSID: ");
     Serial.println(wifiSSID);
     Serial.print("✓ AP IP: ");
diff --git a/index.h b/index.h
index 5b23885..05d27f6 100644
--- a/index.h
+++ b/index.h
@@ -377,6 +377,7 @@ const char index_html[] PROGMEM = R"rawliteral(
         }
         .file-item {
             background: white;
+            border: 1px solid #e0e0e0;
             padding: 12px;
             margin-bottom: 10px;
             border-radius: 8px;
@@ -399,6 +400,15 @@ const char index_html[] PROGMEM = R"rawliteral(
             border: 2px solid #11998e;
             background: linear-gradient(135deg, rgba(17, 153, 142, 0.05) 0%, rgba(56, 239, 125, 0.05) 100%);
         }
+        .file-item.selected {
+            border: 2px solid #667eea;
+            background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
+        }
+        .file-checkbox {
+            width: 20px;
+            height: 20px;
+            cursor: pointer;
+        }
         .file-info {
             flex: 1;
             min-width: 200px;
@@ -724,6 +734,12 @@ const char index_html[] PROGMEM = R"rawliteral(
             </div>
             
             <h2>Log Files</h2>
+            <div class="control-row" style="margin-bottom: 10px;">
+                <button onclick="selectAllFiles()" style="background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);">Select All</button>
+                <button onclick="deselectAllFiles()" style="background: linear-gradient(135deg, #bdc3c7 0%, #95a5a6 100%);">Deselect All</button>
+                <button onclick="downloadSelectedFiles()" style="background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);">Download Selected</button>
+                <button onclick="deleteSelectedFiles()" style="background: linear-gradient(135deg, #eb3349 0%, #f45c43 100%);">Delete Selected</button>
+            </div>
             <div class="file-list" id="file-list">
                 <p style="text-align: center; color: #666; font-size: 0.9em;">Loading...</p>
             </div>
@@ -1068,6 +1084,9 @@ const char index_html[] PROGMEM = R"rawliteral(
                 }
                 
                 fileItem.innerHTML = 
+                    '<input type="checkbox" class="file-checkbox" data-filename="' + file.name + '" ' +
+                    'onchange="toggleFileSelection(this)" ' + 
+                    (isLogging ? 'disabled' : '') + '>' +
                     '<div class="file-info">' +
                         nameHtml +
                         '<div class="file-size">' + formatBytes(file.size) + '</div>' +
@@ -1223,6 +1242,88 @@ const char index_html[] PROGMEM = R"rawliteral(
             }
         }
         
+        // 파일 선택 관리 함수들
+        function toggleFileSelection(checkbox) {
+            const fileItem = checkbox.closest('.file-item');
+            if (checkbox.checked) {
+                fileItem.classList.add('selected');
+            } else {
+                fileItem.classList.remove('selected');
+            }
+        }
+        
+        function selectAllFiles() {
+            const checkboxes = document.querySelectorAll('.file-checkbox:not(:disabled)');
+            checkboxes.forEach(cb => {
+                cb.checked = true;
+                cb.closest('.file-item').classList.add('selected');
+            });
+        }
+        
+        function deselectAllFiles() {
+            const checkboxes = document.querySelectorAll('.file-checkbox');
+            checkboxes.forEach(cb => {
+                cb.checked = false;
+                cb.closest('.file-item').classList.remove('selected');
+            });
+        }
+        
+        function getSelectedFiles() {
+            const selected = [];
+            const checkboxes = document.querySelectorAll('.file-checkbox:checked');
+            checkboxes.forEach(cb => {
+                selected.push(cb.dataset.filename);
+            });
+            return selected;
+        }
+        
+        function downloadSelectedFiles() {
+            const selected = getSelectedFiles();
+            if (selected.length === 0) {
+                alert('Please select files to download.');
+                return;
+            }
+            
+            // 각 파일을 순차적으로 다운로드
+            selected.forEach((filename, index) => {
+                setTimeout(() => {
+                    downloadFile(filename);
+                }, index * 500);  // 500ms 간격으로 다운로드
+            });
+            
+            console.log('Downloading files:', selected);
+        }
+        
+        function deleteSelectedFiles() {
+            const selected = getSelectedFiles();
+            if (selected.length === 0) {
+                alert('Please select files to delete.');
+                return;
+            }
+            
+            const message = 'Are you sure you want to delete ' + selected.length + ' file(s)?\n\n' +
+                          'Files:\n' + selected.join('\n') + '\n\n' +
+                          'This action cannot be undone.';
+            
+            if (!confirm(message)) {
+                return;
+            }
+            
+            // 각 파일 삭제
+            selected.forEach(filename => {
+                if (ws && ws.readyState === WebSocket.OPEN) {
+                    ws.send(JSON.stringify({cmd: 'deleteFile', filename: filename}));
+                }
+            });
+            
+            console.log('Deleting files:', selected);
+            
+            // 선택 해제
+            setTimeout(() => {
+                deselectAllFiles();
+            }, 1000);
+        }
+        
         window.addEventListener('load', function() {
             loadCanSpeed();
             loadMcpMode();