diff --git a/go.mod b/go.mod
index 4f6c760..1185ae3 100644
--- a/go.mod
+++ b/go.mod
@@ -1,8 +1,14 @@
-module github.com/gokch/snum_sort
-
-go 1.19
-
-require (
-	github.com/ericlagergren/decimal v0.0.0-20211103172832-aca2edc11f73
-	github.com/google/go-cmp v0.5.9
-)
+module github.com/gokch/snum_sort
+
+go 1.19
+
+require (
+	github.com/ericlagergren/decimal v0.0.0-20211103172832-aca2edc11f73
+	github.com/stretchr/testify v1.8.1
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/go.sum b/go.sum
index 8e668b9..9c00c8b 100644
--- a/go.sum
+++ b/go.sum
@@ -1,10 +1,25 @@
 github.com/apmckinlay/gsuneido v0.0.0-20190404155041-0b6cd442a18f/go.mod h1:JU2DOj5Fc6rol0yaT79Csr47QR0vONGwJtBNGRD7jmc=
 github.com/cockroachdb/apd v1.1.0/go.mod h1:8Sl8LxpKi29FqWXR16WEFZRNSz3SoPzUzeMeY4+DwBQ=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/ericlagergren/decimal v0.0.0-20211103172832-aca2edc11f73 h1:odNUt+pGupjtZyfaNIGLT/PUxT7r3fZ0Kf+QH9reIoM=
 github.com/ericlagergren/decimal v0.0.0-20211103172832-aca2edc11f73/go.mod h1:5sruVSMrZCk0U4hwRaGD0D8wIMFVsBWQqG74jQDFg4k=
-github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
-github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/lib/pq v1.0.0/go.mod h1:5WUZQaWbwv1U+lTReE5YruASi9Al49XbQIvNi/34Woo=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/shopspring/decimal v0.0.0-20180709203117-cd690d0c9e24/go.mod h1:M+9NzErvs504Cn4c5DxATwIqPbtswREoFCre64PpcG4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/inf.v0 v0.9.1/go.mod h1:cWUDdTG/fYaXco+Dcufb5Vnc6Gp2YChqWtbxRZE0mXw=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/sort/define.go b/sort/define.go
index f718451..6050842 100644
--- a/sort/define.go
+++ b/sort/define.go
@@ -10,5 +10,4 @@ const (
 
 	DEF_headerBitMaskSign        byte = 128 // 1000 0000
 	DEF_headerBitMaskStandardLen byte = 127 // 0111 1111
-	DEF_headerValueSignPlus      byte = DEF_headerBitMaskSign
 )
diff --git a/sort/sort.go b/sort/sort.go
index 6eb37db..8bc3315 100644
--- a/sort/sort.go
+++ b/sort/sort.go
@@ -18,21 +18,20 @@ type SnumSort struct {
 }
 
 func (t *SnumSort) Encode() (enc []byte, err error) {
-	// 문자열 추출
-	var bigRaw *big.Int
+	// get raw
 	bigRaw, lenDecimal, isMinus := t.Snum.GetRaw()
 	raw := bigRaw.String()
-	if raw == "0" { // s_num 이 0일 경우 후처리
+	if raw == "0" { // 0 일 경우 전처리
 		lenDecimal = DEF_digitDecimalMax
 	}
 	lenTotal := len(raw)
 
-	// 헤더 제작
+	// make header
 	posStartDot := t.makePosStartDot(lenTotal, lenDecimal)
-	header := t.encodeHeader(posStartDot, isMinus)
+	header := t.encodeHeader(posStartDot)
 
-	// 데이터 제작
-	dataCompress := make([]byte, 0, lenTotal) // n_len / 2 + (n_len%2!=0)?1:0
+	// make body
+	dataCompress := make([]byte, 0, lenTotal) // len / 2 + (len%2!=0)?1:0
 	numOri := []byte(raw)
 	for i := 0; i < lenTotal; i++ {
 		b4 := numOri[i] - byte('0')
@@ -42,18 +41,18 @@ func (t *SnumSort) Encode() (enc []byte, err error) {
 			dataCompress[i/2] += b4
 		}
 	}
-	// 부호가 음수(-) 일 경우 데이터 비트 반전
+	// if minus, reverse bit
 	if isMinus == true {
+		header = ^header
 		lenData := len(dataCompress)
 		for i := 0; i < lenData; i++ {
-			dataCompress[i] = ^dataCompress[i] // 비트 반전
+			dataCompress[i] = ^dataCompress[i]
 		}
 
-		// 음수의 경우 무조건 끝에 역정렬 알고리즘을 위한 비교마감(cut) 수치 0xFF 를 넣는다.
-		dataCompress = append(dataCompress, 0xFF)
+		dataCompress = append(dataCompress, 0xFF) // append last 0xFF
 	}
 
-	// 헤더와 데이터를 합쳐 bt_ret 제작
+	// make enc
 	enc = make([]byte, 0, DEF_lenHeader+(lenTotal/2))
 	enc = append(enc, header)
 	enc = append(enc, dataCompress...)
@@ -65,26 +64,22 @@ func (t *SnumSort) Decode(enc []byte) (err error) {
 		return errors.New("too short")
 	}
 
-	// 헤더 정보 추출 - 부호 / 길이
+	// Decode header info
 	isMinus, lenHeader := t.decodeHeader(enc[0])
-	if len(enc) == 2 && enc[1] == 0 { // _bt_num 이 0 일 경우 후처리
+	if len(enc) == 2 && enc[1] == 0 { // 0 일 경우 후처리
 		lenHeader = byte(DEF_digitDecimalMax)
 	}
 
-	// 데이터 추출 및 big int 설정
-	var sRaw string
 	data := enc[1:]
-	// 전처리 - 헤더에 따른 정보가 음수 일 경우
 	if isMinus == true {
-		// 마지막 0xFF 분리
-		data = data[:len(data)-1]
-		// 비트 반전(데이터)
-		for i := 0; i < len(data); i++ {
+		data = data[:len(data)-1]        // separate last 0xFF
+		for i := 0; i < len(data); i++ { // reverse bit
 			data[i] = ^data[i]
 		}
 	}
 
-	// string 제작
+	// make string
+	var sRaw string
 	for i := 0; i < len(data); i++ {
 		high4bit := data[i] >> 4
 		low4bit := data[i] - (high4bit << 4)
@@ -92,11 +87,11 @@ func (t *SnumSort) Decode(enc []byte) (err error) {
 		sRaw += string('0' + low4bit)
 	}
 
-	// total, decimal len 추출
+	// set total, decimal len
 	lenTotal := len(sRaw)
 	lenDecimal := t.makeLenDecimal(lenTotal, lenHeader)
 
-	// snum 세팅
+	// set snum
 	big, _ := big.NewInt(0).SetString(sRaw, 10)
 	t.Snum.SetRaw(big, lenDecimal, isMinus)
 	return nil
@@ -109,7 +104,6 @@ func (t *SnumSort) decodeHeader(header byte) (isMinus bool, lenStandard byte) {
 	if header&DEF_headerBitMaskSign == 0 {
 		// 부호(+-) 추출
 		isMinus = true
-		// 음수일 경우 헤더 보수처리
 		header = ^header
 	}
 
@@ -131,13 +125,7 @@ func (t *SnumSort) makePosStartDot(lenTotal int, lenDecimal int) (posStartDot in
 	return posStartDot
 }
 
-func (t *SnumSort) encodeHeader(posStartDot int, isMinus bool) (header byte) {
-	// 헤더 제작 - 제작시 양수로 가정하고 제작 후 -> 후 처리에서 음수를 반영
-	header = DEF_headerValueSignPlus | byte(posStartDot)
-
-	// 음수의 경우 비트반전
-	if isMinus == true {
-		header = ^header
-	}
+func (t *SnumSort) encodeHeader(posStartDot int) (header byte) {
+	header = DEF_headerBitMaskSign | byte(posStartDot)
 	return header
 }
diff --git a/sort/sort_test.go b/sort/sort_test.go
index 798196c..2ba3ea4 100644
--- a/sort/sort_test.go
+++ b/sort/sort_test.go
@@ -6,41 +6,28 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/require"
 )
 
-func Test_encode_decode(_t *testing.T) {
+// Byte_encode, Byte_decode
+// string -> bigint -> binary -> bigint -> string
+func TestSort_encode_decode(t *testing.T) {
 	fn := func(input string, expect string) {
 		if expect == "" {
 			expect = input
 		}
-
-		// Byte_encode, Byte_decode
-		// string -> bigint -> binary -> bigint -> string
 		numSort := NewSnumSort(input)
 
 		enc, err := numSort.Encode()
-		if err != nil {
-			_t.Error(err)
-			return
-		}
+		require.NoError(t, err)
 
 		err = numSort.Decode(enc)
-		if err != nil {
-			_t.Error(err)
-			return
-		}
+		require.NoError(t, err)
 
 		recovery, err := numSort.GetStr()
-		if err != nil {
-			_t.Error(err)
-			return
-		}
+		require.NoError(t, err)
 
-		if expect != recovery {
-			_t.Errorf("expect: %s, recovery: %s", expect, recovery)
-			return
-		}
+		require.Equalf(t, expect, recovery, "input - %s", input)
 	}
 
 	// 0
@@ -166,40 +153,36 @@ func Test_encode_decode(_t *testing.T) {
 	}
 }
 
-func Test_sort(_t *testing.T) {
+func Test_sort(t *testing.T) {
 	type Input struct {
-		Sn string
-		Bt []byte
+		snum   string
+		encode []byte
 	}
 
 	oris := make([]*Input, 0, 100)
-	checks := make([]*Input, 0, 100)
+	sorts := make([]*Input, 0, 100)
 
 	input := func(snum string) {
 		sorted := NewSnumSort(snum)
 		bt, err := sorted.Encode()
-		if err != nil {
-			_t.Errorf("input - %s | err - %v", snum, err)
-		}
+		require.NoError(t, err)
 
-		data := &Input{Sn: snum, Bt: bt}
+		data := &Input{snum: snum, encode: bt}
 		oris = append(oris, data)
-		checks = append(checks, data)
+		sorts = append(sorts, data)
 	}
 
-	check := func() {
+	sort := func() {
 		// sort checks
-		sort.SliceStable(checks, func(i, j int) bool {
-			cmp := bytes.Compare(checks[i].Bt, checks[j].Bt)
-			if cmp == 1 {
+		sort.SliceStable(sorts, func(i, j int) bool {
+			cmp := bytes.Compare(sorts[i].encode, sorts[j].encode)
+			if cmp < 0 {
 				return true
 			}
 			return false
 		})
 		// cmp ori and sorts
-		if cmp.Diff(oris, checks) != "" {
-			_t.Errorf("err - oris != sorts\n%s", cmp.Diff(oris, checks))
-		}
+		require.EqualValues(t, oris, sorts)
 	}
 	input("-" + strings.Repeat("9", DEF_digitIntegerMax) + "." + strings.Repeat("9", DEF_digitDecimalMax)) // 음수 최소값
 	input("-" + strings.Repeat("9", DEF_digitIntegerMax))
@@ -243,6 +226,6 @@ func Test_sort(_t *testing.T) {
 	input(strings.Repeat("9", DEF_digitIntegerMax))
 	input(strings.Repeat("9", DEF_digitIntegerMax) + "." + strings.Repeat("9", DEF_digitDecimalMax)) // 양수 최대값
 
-	check()
+	sort()
 	// print()
 }