diff --git a/.circleci/config.yml b/.circleci/config.yml
index 1a9c4c8..0c09c00 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,44 +1,132 @@
-version: 2
-jobs:
-  build:
+alias:
+  default: &default
     working_directory: /go/src/github.com/yahoojapan/gongt
     docker:
-      - image: circleci/golang:1.10.1
+      - image: circleci/golang:1.11.4
         environment:
-          GO15VENDOREXPERIMENT: 1
+          GOPATH: "/go"
+          GO111MODULE: "on"
           LD_LIBRARY_PATH: /usr/local/lib
-    environment:
-      TEST_RESULTS: /tmp/test-results
+          NGT_VERSION: 1.6.1
+          REPO_NAME: "yahoojapan"
+          IMAGE_NAME: "gongt"
+          GITHUB_API: "https://api.github.com/"
+      - image: redis
+
+version: 2
+jobs:
+  test:
+    <<: *default
     steps:
       - checkout
+      - restore_cache:
+          key: gosum-{{ .Branch }}-{{ checksum "go.sum" }}
       - run:
-          name: preparation
+          name: install dependencies
           command: |
-            mkdir -p $TEST_RESULTS
             sudo apt-get update
             sudo apt-get install cmake
-            cd ~
-            git clone https://github.com/yahoojapan/NGT
-            mkdir -p NGT/build
-            cd NGT/build
-            cmake ..
-            make -j
-            sudo make install
-            go get -u github.com/jstemmer/go-junit-report
-            cd /go/src/github.com/yahoojapan/gongt
-            make init
+            sudo apt-get install libhdf5-dev
+            sudo -E make deps
       - run:
-          name: run test
+          name: preparation
           command: |
-            trap "go-junit-report < ${TEST_RESULTS}/go-test.out > ${TEST_RESULTS}/go-test-report.xml" EXIT
-            go test -v -race -coverprofile=coverage.out -covermode=atomic gongt.go gongt_test.go | tee ${TEST_RESULTS}/go-test.out
+            go mod vendor
       - run:
-          name: prepare bench
+          name: run tests
           command: |
-            sudo apt-get install libhdf5-dev
-            make download
-            make index
+            rm -rf example
+            go test -v -race -covermode=atomic -coverprofile=coverage.out ./...
+            go tool cover -html=coverage.out -o coverage.html
+            bash <(curl -s https://codecov.io/bash)
+      - store_artifacts:
+          path: ./coverage.html
+      - save_cache:
+          key: gosum-{{ .Branch }}-{{ checksum "go.sum" }}
+          paths:
+            - ./vendor
+  versioning:
+    <<: *default
+    steps:
+      - checkout
+      - run:
+          name: check
+          command: |
+            mkdir -p $HOME/.ssh/ && echo -e "Host github.com\n\tStrictHostKeyChecking no\n" > ~/.ssh/config
+            LAST_COMMIT=`git log -1 --pretty=%B`
+            VERSION=`git describe --abbrev=0 --tags`
+            touch ./.tag
+            if [ ! -z "`git diff $VERSION`" -o -z "$VERSION" ]; then
+              VERSION=${VERSION:-'0.0.0'}
+              MAJOR="${VERSION%%.*}"; VERSION="${VERSION#*.}"
+              MINOR="${VERSION%%.*}"; VERSION="${VERSION#*.}"
+              PATCH="${VERSION%%.*}"; VERSION="${VERSION#*.}"
+              if echo $LAST_COMMIT | grep "\[\(major\|MAJOR\)\]" > /dev/null; then
+                MAJOR=$((MAJOR+1))
+                echo "$MAJOR.0.0" > ./.tag
+              elif echo $LAST_COMMIT | grep "\[\(minor\|MINOR\)\]" > /dev/null; then
+                MINOR=$((MINOR+1))
+                echo "$MAJOR.$MINOR.0" > ./.tag
+              elif echo $LAST_COMMIT | grep "\[\(patch\|PATCH\)\]" > /dev/null; then
+                PATCH=$((PATCH+1))
+                echo "$MAJOR.$MINOR.$PATCH" > ./.tag
+              fi
+            fi
+      - persist_to_workspace:
+          root: .
+          paths:
+            - .
+  push:
+    <<: *default
+    steps:
+      - attach_workspace:
+          at: .
       - run:
-          name: run bench
+          name: push tag and check PR body
           command: |
-            make bench
+            mkdir -p $HOME/.ssh/ && echo -e "Host github.com\n\tStrictHostKeyChecking no\n" > ~/.ssh/config
+            TAG=`cat ./.tag`
+            if [ ! -z "$TAG" ]; then
+              echo $TAG
+              git tag $TAG
+              git push https://${GITHUB_ACCESS_TOKEN}:x-oauth-basic@github.com/${REPO_NAME}/${IMAGE_NAME} --tags
+              # git push git@github.com:${REPO_NAME}/${IMAGE_NAME} --tags
+            fi
+      - persist_to_workspace:
+          root: .
+          paths:
+            - .
+  gh_release:
+    <<: *default
+    steps:
+      - attach_workspace:
+          at: .
+      - run:
+          name: release
+          command: |
+            mkdir -p $HOME/.ssh/ && echo -e "Host github.com\n\tStrictHostKeyChecking no\n" > ~/.ssh/config
+            TAG=`cat ./.tag`
+            if [ ! -z "$TAG" ]; then
+              echo "Create release: ${TAG}"
+              curl -H "Authorization: token ${GITHUB_ACCESS_TOKEN}" \
+                   -X POST \
+                   -d "{\"tag_name\": \"${TAG}\"}" \
+                   ${GITHUB_API}repos/${REPO_NAME}/${IMAGE_NAME}/releases
+            fi
+
+workflows:
+  version: 2
+  build:
+    jobs:
+      - test
+      - versioning:
+          filters:
+            branches:
+              only:
+                - master
+      - push:
+          requires:
+            - versioning
+      - gh_release:
+          requires:
+            - push
diff --git a/Makefile b/Makefile
index 40f4f35..1558043 100644
--- a/Makefile
+++ b/Makefile
@@ -4,9 +4,12 @@ GO_VERSION := $(shell go version)
 REVISION := $(shell git rev-parse --short HEAD)
 PROJECT_ROOT := $(shell pwd)
 
-init:
-	go get -u github.com/golang/dep/cmd/dep
-	dep ensure
+deps:
+	curl -LO https://github.com/yahoojapan/NGT/archive/v$(NGT_VERSION).tar.gz
+	tar zxf v$(NGT_VERSION).tar.gz -C /tmp
+	cd /tmp/NGT-$(NGT_VERSION); cmake .
+	make -j -C /tmp/NGT-$(NGT_VERSION)
+	make install -C /tmp/NGT-$(NGT_VERSION)
 
 build:
 	go build gongt.go
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..522be74
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,6 @@
+module github.com/yahoojapan/gongt
+
+require (
+	github.com/kpango/glg v1.2.7
+	gonum.org/v1/hdf5 v0.0.0-20180702054324-c257073619f4
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..50399d6
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,6 @@
+github.com/kpango/fastime v1.0.0 h1:tZeI+eEyHHYKkTkKOiOZ5MeeRJmliuZlGV7aK7S2rkE=
+github.com/kpango/fastime v1.0.0/go.mod h1:Y5XY5bLG5yc7g2XmMUzc22XYV1XaH+KgUOHkDvLp4SA=
+github.com/kpango/glg v1.2.7 h1:aVnv89IIWXSFNOm93SnDQGIKF27Jzz9olieOL2b23Xc=
+github.com/kpango/glg v1.2.7/go.mod h1:sEwy6Va116x0eKdbVsilHPanIrsoE9AR/9vHwdo4ytQ=
+gonum.org/v1/hdf5 v0.0.0-20180702054324-c257073619f4 h1:3GnLlVt6JOlXwffishXEToqGjH7hx/G8UK7RP7HTqX0=
+gonum.org/v1/hdf5 v0.0.0-20180702054324-c257073619f4/go.mod h1:g+PDU5ogjIKcc3Cg4ALAK7X4c8bBQvPzPKWNW5NB7I0=
diff --git a/gongt.go b/gongt.go
index f522e46..28d715a 100644
--- a/gongt.go
+++ b/gongt.go
@@ -118,8 +118,8 @@ const (
 var (
 	once = &sync.Once{}
 	ngt  *NGT
-	
-	// ErrCAPINotImplemented raises using not implemented function in C API 
+
+	// ErrCAPINotImplemented raises using not implemented function in C API
 	ErrCAPINotImplemented = errors.New("Not implemented in C API")
 )
 
@@ -247,7 +247,7 @@ func SetSearchEdgeSize(size int) *NGT {
 //	gongt.Get().SetSearchEdgeSize(10) // SearchEdgeSize Setting
 //	gongt.New("").SetSearchEdgeSize(10) // SearchEdgeSize Setting
 func (n *NGT) SetSearchEdgeSize(size int) *NGT {
-	if size > 0 {
+	if size >= 0 {
 		n.mu.Lock()
 		n.prop.SearchEdgeSize = size
 		n.mu.Unlock()