diff --git a/src/TensorFlowNET.Core/Operations/Operation.Implicit.cs b/src/TensorFlowNET.Core/Operations/Operation.Implicit.cs
index 9cadac0c..289c69ad 100644
--- a/src/TensorFlowNET.Core/Operations/Operation.Implicit.cs
+++ b/src/TensorFlowNET.Core/Operations/Operation.Implicit.cs
@@ -27,8 +27,12 @@ namespace Tensorflow
         public static implicit operator Operation(IntPtr handle) 
             => new Operation(handle);
 
-        public static implicit operator IntPtr(Operation op) => op._handle;
-        public static implicit operator Tensor(Operation op) => op.output;
+        public static implicit operator IntPtr(Operation op) 
+            => op._handle;
+        public static implicit operator Tensor(Operation op) 
+            => op.output;
+        public static implicit operator RefVariable(Operation op) 
+            => new RefVariable(op);
 
         public override string ToString()
         {
diff --git a/src/TensorFlowNET.Core/Operations/Operation.cs b/src/TensorFlowNET.Core/Operations/Operation.cs
index 029f8d69..65097d5b 100644
--- a/src/TensorFlowNET.Core/Operations/Operation.cs
+++ b/src/TensorFlowNET.Core/Operations/Operation.cs
@@ -106,7 +106,7 @@ namespace Tensorflow
             _outputs = new Tensor[NumOutputs];
             for (int i = 0; i < NumOutputs; i++)
                 _outputs[i] = new Tensor(this, i, OutputType(i));
-
+            
             // Dict mapping op name to file and line information for op colocation
             // context managers.
             _control_flow_context = _graph._get_control_flow_context();
diff --git a/src/TensorFlowNET.Core/TensorFlow.Binding.csproj b/src/TensorFlowNET.Core/TensorFlow.Binding.csproj
index 369c6c81..0e1c7622 100644
--- a/src/TensorFlowNET.Core/TensorFlow.Binding.csproj
+++ b/src/TensorFlowNET.Core/TensorFlow.Binding.csproj
@@ -5,7 +5,7 @@
     <AssemblyName>TensorFlow.NET</AssemblyName>
     <RootNamespace>Tensorflow</RootNamespace>
     <TargetTensorFlow>1.14.1</TargetTensorFlow>
-    <Version>0.14.2.0</Version>
+    <Version>0.15.0</Version>
     <Authors>Haiping Chen, Meinrad Recheis, Eli Belash</Authors>
     <Company>SciSharp STACK</Company>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
@@ -18,13 +18,15 @@
     <Description>Google's TensorFlow full binding in .NET Standard.
 Building, training and infering deep learning models.
 https://tensorflownet.readthedocs.io</Description>
-    <AssemblyVersion>0.14.2.0</AssemblyVersion>
+    <AssemblyVersion>0.15.0.0</AssemblyVersion>
     <PackageReleaseNotes>Changes since v0.14.0:
 1: Add TransformGraphWithStringInputs.
 2: tf.trainer.load_graph, tf.trainer.freeze_graph
-3: Import Protobuf.Text</PackageReleaseNotes>
+3: Import Protobuf.Text
+4: Support YOLOv3 object detection
+5: Add implicitation for Operation to RefVariable</PackageReleaseNotes>
     <LangVersion>7.3</LangVersion>
-    <FileVersion>0.14.2.0</FileVersion>
+    <FileVersion>0.15.0.0</FileVersion>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
     <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
     <SignAssembly>true</SignAssembly>
@@ -33,7 +35,7 @@ https://tensorflownet.readthedocs.io</Description>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <DefineConstants>TRACE;DEBUG;SERIALIZABLE</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;SERIALIZABLE_</DefineConstants>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
@@ -62,7 +64,6 @@ https://tensorflownet.readthedocs.io</Description>
 
   <ItemGroup>
     <PackageReference Include="Google.Protobuf" Version="3.11.3" />
-    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
     <PackageReference Include="NumSharp.Lite" Version="0.1.0" />
     <PackageReference Include="Protobuf.Text" Version="0.4.0" />
   </ItemGroup>
diff --git a/src/TensorFlowNET.Core/Variables/RefVariable.cs b/src/TensorFlowNET.Core/Variables/RefVariable.cs
index c79c5b7f..cff14ec1 100644
--- a/src/TensorFlowNET.Core/Variables/RefVariable.cs
+++ b/src/TensorFlowNET.Core/Variables/RefVariable.cs
@@ -61,7 +61,11 @@ namespace Tensorflow
         {
             _in_graph_mode = true;
 
-            if (variable_def != null)
+            if(initial_value is Operation op)
+            {
+                _init_from_op(op);
+            }
+            else if (variable_def != null)
             {
                 if (initial_value != null)
                     throw new ValueError("variable_def and initial_value are mutually exclusive.");
@@ -73,6 +77,13 @@ namespace Tensorflow
             }
         }
 
+        private void _init_from_op(Operation op)
+        {
+            var g = ops.get_default_graph();
+            _initializer_op = op;
+            _variable = op.output;
+        }
+
         private void _init_from_proto(VariableDef variable_def, string import_scope = "")
         {
             var g = ops.get_default_graph();