diff --git a/.gitignore b/.gitignore
index 952936c..d95d7c7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 /pico-sdk
-/pico-examples
\ No newline at end of file
+/pico-examples
+/**/build/
diff --git a/01_blink/.gitignore b/01_blink/.gitignore
new file mode 100644
index 0000000..42afabf
--- /dev/null
+++ b/01_blink/.gitignore
@@ -0,0 +1 @@
+/build
\ No newline at end of file
diff --git a/01_blink/.vscode/c_cpp_properties.json b/01_blink/.vscode/c_cpp_properties.json
new file mode 100644
index 0000000..d8747d6
--- /dev/null
+++ b/01_blink/.vscode/c_cpp_properties.json
@@ -0,0 +1,17 @@
+{
+    "configurations": [
+        {
+            "name": "Linux GCC ARM",
+            "includePath": [
+                "${workspaceFolder}/**"
+            ],
+            "defines": [],
+            "compilerPath": "/usr/bin/gcc",
+            "cStandard": "c11",
+            "cppStandard": "c++17",
+            "intelliSenseMode":"linux-gcc-arm",
+            "configurationProvider": "ms-vscode.cmake-tools"
+        }
+    ],
+    "version": 4
+}
\ No newline at end of file
diff --git a/01_blink/CMakeLists.txt b/01_blink/CMakeLists.txt
new file mode 100644
index 0000000..1a005fb
--- /dev/null
+++ b/01_blink/CMakeLists.txt
@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.13)
+
+include(pico_sdk_import.cmake)
+
+project(blink C CXX ASM)
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
+pico_sdk_init()
+
+add_executable(blink
+    src/blink.c
+)
+pico_set_program_name(ProjectName "Blink")
+pico_set_program_version(ProjectName "0.1.0")
+
+pico_enable_stdio_usb(blink 1)
+pico_enable_stdio_uart(blink 0)
+
+pico_add_extra_outputs(blink)
+
+target_link_libraries(blink pico_stdlib)
\ No newline at end of file
diff --git a/01_hello_pico/pico_sdk_import.cmake b/01_blink/pico_sdk_import.cmake
similarity index 100%
rename from 01_hello_pico/pico_sdk_import.cmake
rename to 01_blink/pico_sdk_import.cmake
diff --git a/01_blink/run b/01_blink/run
new file mode 100755
index 0000000..09b6b01
--- /dev/null
+++ b/01_blink/run
@@ -0,0 +1,43 @@
+#!/usr/bin/bash
+export PICO_SDK_PATH="/media/elex/UltraFit/pico-sdk"
+ 
+function fn_clean {
+    if [ -d ./build ]
+    then
+        rm -r ./build    
+    fi
+    mkdir build
+}
+
+function fn_cmake {
+    cd build
+    cmake ..
+    cd ..
+}
+
+function fn_make {
+    cd build
+    make
+    cd ..
+}
+
+if [ -z $1 ]
+then
+    fn_clean
+    fn_cmake
+    fn_make
+elif [ $1 == 'clean' ]
+then
+    echo 'Cleaning build dir.'
+    fn_clean
+elif [ $1 == 'cmake' ]
+then
+    echo 'Exec cmake'
+    fn_cmake
+elif [ $1 == 'make' ]
+then
+    echo 'Exec make'
+    fn_make
+else
+    echo 'What do you want???'
+fi
diff --git a/01_blink/src/blink.c b/01_blink/src/blink.c
new file mode 100644
index 0000000..b7d1563
--- /dev/null
+++ b/01_blink/src/blink.c
@@ -0,0 +1,25 @@
+#include <stdlib.h>
+#include "pico/stdlib.h"
+#include "pico/binary_info.h"
+
+const uint LED_PIN = PICO_DEFAULT_LED_PIN;
+
+int main()
+{
+    bi_decl(bi_program_description("Blink"));
+    bi_decl(bi_1pin_with_name(LED_PIN, "On-board LED"));
+
+    gpio_init(LED_PIN);
+    gpio_set_dir(LED_PIN, GPIO_OUT);
+    while (true)
+    {
+        gpio_put(LED_PIN, true);
+        sleep_ms(750);
+        gpio_put(LED_PIN, false);
+        sleep_ms(250);
+        gpio_put(LED_PIN, true);
+        sleep_ms(250);
+        gpio_put(LED_PIN, false);
+        sleep_ms(250);
+    }
+}
\ No newline at end of file
diff --git a/01_hello_pico/.gitignore b/01_hello_pico/.gitignore
deleted file mode 100644
index 7f7adc5..0000000
--- a/01_hello_pico/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-/build
-/.vscode
\ No newline at end of file
diff --git a/02_hello_serial/.gitignore b/02_hello_serial/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/02_hello_serial/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/02_hello_serial/.vscode/c_cpp_properties.json b/02_hello_serial/.vscode/c_cpp_properties.json
new file mode 100644
index 0000000..bc589aa
--- /dev/null
+++ b/02_hello_serial/.vscode/c_cpp_properties.json
@@ -0,0 +1,17 @@
+{
+    "configurations": [
+        {
+            "name": "Linux GCC ARM",
+            "includePath": [
+                "${workspaceFolder}/**"
+            ],
+            "defines": [],
+            "compilerPath": "/usr/bin/gcc",
+            "cStandard": "c11",
+            "cppStandard": "c++17",
+            "intelliSenseMode": "linux-gcc-arm",
+            "configurationProvider": "ms-vscode.cmake-tools"
+        }
+    ],
+    "version": 4
+}
\ No newline at end of file
diff --git a/01_hello_pico/CMakeLists.txt b/02_hello_serial/CMakeLists.txt
similarity index 55%
rename from 01_hello_pico/CMakeLists.txt
rename to 02_hello_serial/CMakeLists.txt
index 26e7844..0511dfa 100644
--- a/01_hello_pico/CMakeLists.txt
+++ b/02_hello_serial/CMakeLists.txt
@@ -11,8 +11,11 @@ add_executable(hello
     src/hello.c
 )
 
-pico_enable_stdio_usb(hello 1)
-pico_enable_stdio_uart(hello 1)
+pico_set_program_name(ProjectName "Hello Serial")
+pico_set_program_version(ProjectName "0.1.0")
+
+pico_enable_stdio_usb(hello 1) # 표준 출력을 USB로
+pico_enable_stdio_uart(hello 0) # 표준 출력을 UART로, 안함.
 
 pico_add_extra_outputs(hello)
 
diff --git a/02_hello_serial/pico_sdk_import.cmake b/02_hello_serial/pico_sdk_import.cmake
new file mode 100644
index 0000000..28efe9e
--- /dev/null
+++ b/02_hello_serial/pico_sdk_import.cmake
@@ -0,0 +1,62 @@
+# This is a copy of <PICO_SDK_PATH>/external/pico_sdk_import.cmake
+
+# This can be dropped into an external project to help locate this SDK
+# It should be include()ed prior to project()
+
+if (DEFINED ENV{PICO_SDK_PATH} AND (NOT PICO_SDK_PATH))
+    set(PICO_SDK_PATH $ENV{PICO_SDK_PATH})
+    message("Using PICO_SDK_PATH from environment ('${PICO_SDK_PATH}')")
+endif ()
+
+if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT} AND (NOT PICO_SDK_FETCH_FROM_GIT))
+    set(PICO_SDK_FETCH_FROM_GIT $ENV{PICO_SDK_FETCH_FROM_GIT})
+    message("Using PICO_SDK_FETCH_FROM_GIT from environment ('${PICO_SDK_FETCH_FROM_GIT}')")
+endif ()
+
+if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT_PATH} AND (NOT PICO_SDK_FETCH_FROM_GIT_PATH))
+    set(PICO_SDK_FETCH_FROM_GIT_PATH $ENV{PICO_SDK_FETCH_FROM_GIT_PATH})
+    message("Using PICO_SDK_FETCH_FROM_GIT_PATH from environment ('${PICO_SDK_FETCH_FROM_GIT_PATH}')")
+endif ()
+
+set(PICO_SDK_PATH "${PICO_SDK_PATH}" CACHE PATH "Path to the Raspberry Pi Pico SDK")
+set(PICO_SDK_FETCH_FROM_GIT "${PICO_SDK_FETCH_FROM_GIT}" CACHE BOOL "Set to ON to fetch copy of SDK from git if not otherwise locatable")
+set(PICO_SDK_FETCH_FROM_GIT_PATH "${PICO_SDK_FETCH_FROM_GIT_PATH}" CACHE FILEPATH "location to download SDK")
+
+if (NOT PICO_SDK_PATH)
+    if (PICO_SDK_FETCH_FROM_GIT)
+        include(FetchContent)
+        set(FETCHCONTENT_BASE_DIR_SAVE ${FETCHCONTENT_BASE_DIR})
+        if (PICO_SDK_FETCH_FROM_GIT_PATH)
+            get_filename_component(FETCHCONTENT_BASE_DIR "${PICO_SDK_FETCH_FROM_GIT_PATH}" REALPATH BASE_DIR "${CMAKE_SOURCE_DIR}")
+        endif ()
+        FetchContent_Declare(
+                pico_sdk
+                GIT_REPOSITORY https://github.com/raspberrypi/pico-sdk
+                GIT_TAG master
+        )
+        if (NOT pico_sdk)
+            message("Downloading Raspberry Pi Pico SDK")
+            FetchContent_Populate(pico_sdk)
+            set(PICO_SDK_PATH ${pico_sdk_SOURCE_DIR})
+        endif ()
+        set(FETCHCONTENT_BASE_DIR ${FETCHCONTENT_BASE_DIR_SAVE})
+    else ()
+        message(FATAL_ERROR
+                "SDK location was not specified. Please set PICO_SDK_PATH or set PICO_SDK_FETCH_FROM_GIT to on to fetch from git."
+                )
+    endif ()
+endif ()
+
+get_filename_component(PICO_SDK_PATH "${PICO_SDK_PATH}" REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
+if (NOT EXISTS ${PICO_SDK_PATH})
+    message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' not found")
+endif ()
+
+set(PICO_SDK_INIT_CMAKE_FILE ${PICO_SDK_PATH}/pico_sdk_init.cmake)
+if (NOT EXISTS ${PICO_SDK_INIT_CMAKE_FILE})
+    message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' does not appear to contain the Raspberry Pi Pico SDK")
+endif ()
+
+set(PICO_SDK_PATH ${PICO_SDK_PATH} CACHE PATH "Path to the Raspberry Pi Pico SDK" FORCE)
+
+include(${PICO_SDK_INIT_CMAKE_FILE})
diff --git a/01_hello_pico/run b/02_hello_serial/run
similarity index 90%
rename from 01_hello_pico/run
rename to 02_hello_serial/run
index 7594c11..91417d2 100755
--- a/01_hello_pico/run
+++ b/02_hello_serial/run
@@ -1,4 +1,5 @@
 #!/usr/bin/bash
+export PICO_SDK_PATH="/media/elex/UltraFit/pico-sdk"
 
 function fn_clean {
     if [ -d ./build ]
diff --git a/01_hello_pico/src/hello.c b/02_hello_serial/src/hello.c
similarity index 58%
rename from 01_hello_pico/src/hello.c
rename to 02_hello_serial/src/hello.c
index a015923..5c8e4c4 100644
--- a/01_hello_pico/src/hello.c
+++ b/02_hello_serial/src/hello.c
@@ -7,8 +7,8 @@ const uint LED_PIN = 25;
 
 int main()
 {
-    //bi_decl(bi_program_description("This is a test binary."));
-    //(bi_1pin_with_name(LED_PIN, "On-board LED"));
+    bi_decl(bi_program_description("Hello Serial via USB."));
+    bi_decl(bi_1pin_with_name(LED_PIN, "On-board LED"));
 
     stdio_init_all();
 
@@ -17,10 +17,10 @@ int main()
 
     while (true)
     {
-        gpio_put(LED_PIN, 0);
+        gpio_put(LED_PIN, false);
         sleep_ms(250);
-        gpio_put(LED_PIN, 1);
-        puts("Hello World~~!\n");
+        gpio_put(LED_PIN, true);
+        puts("Hello World~~!");
         sleep_ms(1000);
     }
 }
\ No newline at end of file