diff --git a/src/app/asset-calculator/asset-calculator.component.ts b/src/app/asset-calculator/asset-calculator.component.ts
index e25cab9..b32282e 100644
--- a/src/app/asset-calculator/asset-calculator.component.ts
+++ b/src/app/asset-calculator/asset-calculator.component.ts
@@ -3,7 +3,7 @@ import {ReactiveFormsModule,  FormGroup, Validators, FormControl, FormArray} fro
 import {CurrencyPipe,DecimalPipe,PercentPipe} from '@angular/common';
 
 
-import {Asset, Positions, AssetPlanPosition, TypeDepreciation, YearMonth, AssetLifeChange } from './assets/asset';
+import {Asset, Positions, AssetPlanPosition, TypeDepreciation, YearMonth, AssetLifeChange, YearMonthUtil } from './assets/asset';
 import {AssetService} from './assets/service/asset.service'
 
 
@@ -46,7 +46,7 @@ interface FormValues {
 		const savedAsset = localStorage.getItem('assetForCalculator');
 		if( savedAsset ) {
 			const asset = JSON.parse( savedAsset );
-		   	this.controlsFromAsset( asset );
+		   	this.assetToControls( asset );
 		}
     }
 
@@ -60,9 +60,9 @@ interface FormValues {
 
 	}
 
-	private controlsFromAsset( asset : Asset )  {
+	private assetToControls( asset : Asset )  {
 		if( asset.life.length > 0){
-			const year_month = asset.life[0].when.year +'-'+asset.life[0].when.month;
+			const year_month = YearMonthUtil.toString( asset.life[0].when );
 			this.assetsDepreciationFormGroup.patchValue({
 				year_month        : year_month,
 				initialValueAsset : asset.life[0].initial,
@@ -74,12 +74,10 @@ interface FormValues {
 
 				this.addChangeValue();
 	
-				const row : FormGroup = this.lifeFormArray.controls[ i - 1 ];
+				const row        : FormGroup = this.lifeFormArray.controls[ i - 1 ];
 				const lifeChange : AssetLifeChange = asset.life[i];
 				row.get( 'initialValueAsset' )?.setValue( lifeChange.initial);
-				const ym : YearMonth = lifeChange.when;
-				//const when_txt = ym.toFormValue();
-				row.get( 'year_month' )?.setValue( lifeChange.when.year +'-' +  lifeChange.when.month );
+				row.get( 'year_month' )?.setValue( YearMonthUtil.toString( lifeChange.when ) );
 	
 			
 			}
@@ -98,7 +96,7 @@ interface FormValues {
 		for( let changeControlGroup of this.lifeFormArray.controls ) {
 			const initialValueAsset = changeControlGroup.get('initialValueAsset')?.value;
 			const year_month = changeControlGroup.get('year_month')?.value;
-			asset.addChange(new AssetLifeChange(new YearMonth(year_month), initialValueAsset, 0, 0));
+			asset.addChange(new AssetLifeChange( new YearMonth(year_month), initialValueAsset, 0, 0));
 		}
 		return asset;
 	}
diff --git a/src/app/asset-calculator/assets/asset.ts b/src/app/asset-calculator/assets/asset.ts
index 4167b94..c5b9f28 100644
--- a/src/app/asset-calculator/assets/asset.ts
+++ b/src/app/asset-calculator/assets/asset.ts
@@ -4,27 +4,26 @@ export enum TypeDepreciation{
 }
 
 export class YearMonth{
+
     readonly year  : number ;
     readonly month : number ;
+    constructor( year_month:string  ){
+        const [year, month] = year_month.split('-').map(Number);
+        this.year = year;
+        this.month = month;
 
-    constructor( year_month:string | YearMonth ){
-        if (typeof year_month === 'string') {
-            const [year, month] = year_month.split('-').map(Number);
-            this.year = year;
-            this.month = month;
-        } else {
-            this.year = year_month.year;
-            this.month = year_month.month;
-        }
-        
     }
-    
-    toFormValue() {
-        return `${this.year}-${this.month.toString().padStart(2, '0')}`;
+
+}  
+
+export class YearMonthUtil{
+    static toString( ym : YearMonth ):string{
+        return ym.year + '-' + ym.month ;
     }
 }
 
 
+
 export class AssetLifeChange{
     readonly when           : YearMonth;
     readonly initial        : number;