diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9db9ebf..65d1144 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
-project(UECS VERSION 0.9.7)
+project(UECS VERSION 0.9.8)
 message(STATUS "[Project] ${PROJECT_NAME}")
 
 include(cmake/InitUCMake.cmake)
diff --git a/include/UECS/CmptPtr.h b/include/UECS/CmptPtr.h
index 9ac908d..13598ea 100644
--- a/include/UECS/CmptPtr.h
+++ b/include/UECS/CmptPtr.h
@@ -4,7 +4,7 @@
 
 #include <cassert>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// CmptType + void*
 	class CmptPtr {
 	public:
diff --git a/include/UECS/CmptTag.h b/include/UECS/CmptTag.h
index 06a4f59..c5c8545 100644
--- a/include/UECS/CmptTag.h
+++ b/include/UECS/CmptTag.h
@@ -2,7 +2,7 @@
 
 #include <UTemplate/Typelist.h>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	namespace CmptTag {
 		// LastFrame -> Write -> Latest
 
diff --git a/include/UECS/CmptType.h b/include/UECS/CmptType.h
index fa00a21..aac069e 100644
--- a/include/UECS/CmptType.h
+++ b/include/UECS/CmptType.h
@@ -2,7 +2,7 @@
 
 #include <UTemplate/TypeID.h>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// Component Type
 	// use a hashcode to distinguish different type
 	class CmptType {
diff --git a/include/UECS/Entity.h b/include/UECS/Entity.h
index f4696e7..fc94a24 100644
--- a/include/UECS/Entity.h
+++ b/include/UECS/Entity.h
@@ -2,7 +2,7 @@
 
 #include "detail/Util.h"
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// index + version
 	class Entity {
 	public:
diff --git a/include/UECS/EntityFilter.h b/include/UECS/EntityFilter.h
index 7c5776a..1b0db51 100644
--- a/include/UECS/EntityFilter.h
+++ b/include/UECS/EntityFilter.h
@@ -6,7 +6,7 @@
 
 #include <set>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// filter Archetype with All, Any and None
 	class EntityFilter {
 	public:
diff --git a/include/UECS/EntityLocator.h b/include/UECS/EntityLocator.h
index cb50a2e..3ae4237 100644
--- a/include/UECS/EntityLocator.h
+++ b/include/UECS/EntityLocator.h
@@ -6,7 +6,7 @@
 
 #include <set>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// locate components in function's argument list for Archetype
 	class EntityLocator {
 	public:
diff --git a/include/UECS/EntityMngr.h b/include/UECS/EntityMngr.h
index f524317..cff230d 100644
--- a/include/UECS/EntityMngr.h
+++ b/include/UECS/EntityMngr.h
@@ -9,7 +9,7 @@
 
 #include <mutex>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class World;
 
 	class IListener;
diff --git a/include/UECS/EntityQuery.h b/include/UECS/EntityQuery.h
index 574e7f1..dc91465 100644
--- a/include/UECS/EntityQuery.h
+++ b/include/UECS/EntityQuery.h
@@ -3,7 +3,7 @@
 #include "EntityFilter.h"
 #include "EntityLocator.h"
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// EntityFilter + EntityLocator
 	class EntityQuery {
 	public:
diff --git a/include/UECS/IListener.h b/include/UECS/IListener.h
index 3c9598c..25edca1 100644
--- a/include/UECS/IListener.h
+++ b/include/UECS/IListener.h
@@ -2,7 +2,7 @@
 
 #include <string_view>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class World;
 	class SystemMngr;
 	class EntityMngr;
diff --git a/include/UECS/RTDCmptTraits.h b/include/UECS/RTDCmptTraits.h
index d925d3f..b38bf2a 100644
--- a/include/UECS/RTDCmptTraits.h
+++ b/include/UECS/RTDCmptTraits.h
@@ -5,7 +5,7 @@
 #include <unordered_map>
 #include <functional>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// run-time dynamic component traits, singleton
 	// size (> 0) is neccessary
 	// optional
diff --git a/include/UECS/RTDCmptsView.h b/include/UECS/RTDCmptsView.h
index 7c17f4b..9ad2aec 100644
--- a/include/UECS/RTDCmptsView.h
+++ b/include/UECS/RTDCmptsView.h
@@ -6,7 +6,7 @@
 
 #include <set>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class EntityLocator;
 
 	// use RTDCmptsView::Iterator to read CmptPtr
diff --git a/include/UECS/Schedule.h b/include/UECS/Schedule.h
index 342cbaa..c0ba265 100644
--- a/include/UECS/Schedule.h
+++ b/include/UECS/Schedule.h
@@ -8,11 +8,11 @@
 
 #include <map>
 
-namespace Ubpa::detail::Schedule_ {
+namespace Ubpa::UECS::detail::Schedule_ {
 	struct Compiler;
 }
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class EntityMngr;
 	class SystemMngr;
 
diff --git a/include/UECS/SystemFunc.h b/include/UECS/SystemFunc.h
index de061d7..c2806ce 100644
--- a/include/UECS/SystemFunc.h
+++ b/include/UECS/SystemFunc.h
@@ -6,7 +6,7 @@
 
 #include <functional>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// [description]
 	// system function registered by Schedule in <System>::OnUpdate(Schedule&)
 	// name + query + function<...>
diff --git a/include/UECS/SystemMngr.h b/include/UECS/SystemMngr.h
index 4d2b2ce..43dd9ef 100644
--- a/include/UECS/SystemMngr.h
+++ b/include/UECS/SystemMngr.h
@@ -4,7 +4,7 @@
 
 #include <UContainer/xSTL/xMap.h>
 
-namespace Ubpa{
+namespace Ubpa::UECS{
 	class IListener;
 
 	// System Manager
diff --git a/include/UECS/World.h b/include/UECS/World.h
index dc6c1a2..7de9be4 100644
--- a/include/UECS/World.h
+++ b/include/UECS/World.h
@@ -6,7 +6,7 @@
 
 #include <UGraphviz/UGraphviz.h>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class IListener;
 
 	// SystemMngr + EntityMngr
diff --git a/include/UECS/detail/Archetype.h b/include/UECS/detail/Archetype.h
index b5ead3d..b5f3e6d 100644
--- a/include/UECS/detail/Archetype.h
+++ b/include/UECS/detail/Archetype.h
@@ -14,7 +14,7 @@
 
 #include <map>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class EntityMngr;
 
 	// Entity is a special Component
diff --git a/include/UECS/detail/Archetype.inl b/include/UECS/detail/Archetype.inl
index b44225e..64b8740 100644
--- a/include/UECS/detail/Archetype.inl
+++ b/include/UECS/detail/Archetype.inl
@@ -2,7 +2,7 @@
 
 #include <cassert>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename... Cmpts>
 	Archetype::Archetype(TypeList<Cmpts...>)
 		: types(TypeList<Entity, Cmpts...>{})
diff --git a/include/UECS/detail/Chunk.h b/include/UECS/detail/Chunk.h
index 8f791df..697a1f8 100644
--- a/include/UECS/detail/Chunk.h
+++ b/include/UECS/detail/Chunk.h
@@ -5,7 +5,7 @@
 #include <tuple>
 #include <vector>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	using byte = uint8_t;
 	static_assert(sizeof(byte) == 1);
 	struct alignas(128) Chunk {
diff --git a/include/UECS/detail/CmptTag.inl b/include/UECS/detail/CmptTag.inl
index 810a7fd..6e65293 100644
--- a/include/UECS/detail/CmptTag.inl
+++ b/include/UECS/detail/CmptTag.inl
@@ -2,12 +2,12 @@
 
 #include <type_traits>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class Entity;
 	class EntityLocator;
 }
 
-namespace Ubpa::CmptTag {
+namespace Ubpa::UECS::CmptTag {
 	template<typename Cmpt> struct RemoveTag<const Cmpt*> : IType<Cmpt> {};
 	template<typename Cmpt> struct RemoveTag<Cmpt*> : IType<Cmpt> {};
 	template<typename Cmpt> struct RemoveTag<LastFrame<Cmpt>> : IType<Cmpt> {};
diff --git a/include/UECS/detail/CmptType.inl b/include/UECS/detail/CmptType.inl
index 2a270cb..89d542b 100644
--- a/include/UECS/detail/CmptType.inl
+++ b/include/UECS/detail/CmptType.inl
@@ -5,8 +5,8 @@ namespace std {
 	struct hash;
 
 	template<>
-	struct hash<Ubpa::CmptType> {
-		constexpr size_t operator()(const Ubpa::CmptType& t) const noexcept {
+	struct hash<Ubpa::UECS::CmptType> {
+		constexpr size_t operator()(const Ubpa::UECS::CmptType& t) const noexcept {
 			return t.HashCode();
 		}
 	};
diff --git a/include/UECS/detail/CmptTypeSet.h b/include/UECS/detail/CmptTypeSet.h
index 02a2d59..d82f2f5 100644
--- a/include/UECS/detail/CmptTypeSet.h
+++ b/include/UECS/detail/CmptTypeSet.h
@@ -8,7 +8,7 @@
 
 #include <set>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class CmptTypeSet : std::set<CmptType> {
 	public:
 		CmptTypeSet() : hashcode{ TypeID<CmptTypeSet> } {}
diff --git a/include/UECS/detail/CmptTypeSet.inl b/include/UECS/detail/CmptTypeSet.inl
index 1e94021..eee9c6d 100644
--- a/include/UECS/detail/CmptTypeSet.inl
+++ b/include/UECS/detail/CmptTypeSet.inl
@@ -1,6 +1,6 @@
 #pragma once
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	inline CmptTypeSet::CmptTypeSet(const CmptType* types, size_t num) {
 		assert(types != nullptr && num != 0);
 		for (size_t i = 0; i < num; i++)
@@ -106,8 +106,8 @@ namespace Ubpa {
 
 namespace std {
 	template<>
-	struct hash<Ubpa::CmptTypeSet> {
-		size_t operator()(const Ubpa::CmptTypeSet& types) const noexcept {
+	struct hash<Ubpa::UECS::CmptTypeSet> {
+		size_t operator()(const Ubpa::UECS::CmptTypeSet& types) const noexcept {
 			return types.HashCode();
 		}
 	};
diff --git a/include/UECS/detail/EntityFilter.inl b/include/UECS/detail/EntityFilter.inl
index 0a362f8..42880d5 100644
--- a/include/UECS/detail/EntityFilter.inl
+++ b/include/UECS/detail/EntityFilter.inl
@@ -2,7 +2,7 @@
 
 #include "Util.h"
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename... AllCmpts, typename... AnyCmpts, typename... NoneCmpts>
 	EntityFilter::EntityFilter(TypeList<AllCmpts...>, TypeList<AnyCmpts...>, TypeList<NoneCmpts...>)
 		: allCmptTypes{ CmptType::Of<AllCmpts>... },
@@ -125,8 +125,8 @@ namespace std {
 	template<typename T>
 	struct hash;
 	template<>
-	struct hash<Ubpa::EntityFilter> {
-		size_t operator()(const Ubpa::EntityFilter& filter) const noexcept {
+	struct hash<Ubpa::UECS::EntityFilter> {
+		size_t operator()(const Ubpa::UECS::EntityFilter& filter) const noexcept {
 			return filter.HashCode();
 		}
 	};
diff --git a/include/UECS/detail/EntityLocator.inl b/include/UECS/detail/EntityLocator.inl
index 7a98a1a..d4a1f7d 100644
--- a/include/UECS/detail/EntityLocator.inl
+++ b/include/UECS/detail/EntityLocator.inl
@@ -6,7 +6,7 @@
 
 #include <UTemplate/Func.h>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename TaggedCmptList>
 	EntityLocator::EntityLocator(TaggedCmptList)
 		: EntityLocator{ Filter_t<TaggedCmptList, CmptTag::IsLastFrame>{},
diff --git a/include/UECS/detail/EntityMngr.inl b/include/UECS/detail/EntityMngr.inl
index fa413e9..76d4006 100644
--- a/include/UECS/detail/EntityMngr.inl
+++ b/include/UECS/detail/EntityMngr.inl
@@ -5,7 +5,7 @@
 #include <UTemplate/Typelist.h>
 #include <UTemplate/Func.h>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename... Cmpts>
 	Archetype* EntityMngr::GetOrCreateArchetypeOf() {
 		static_assert(IsSet_v<TypeList<Entity, Cmpts...>>,
diff --git a/include/UECS/detail/EntityQuery.inl b/include/UECS/detail/EntityQuery.inl
index 2df9a05..b78aa0d 100644
--- a/include/UECS/detail/EntityQuery.inl
+++ b/include/UECS/detail/EntityQuery.inl
@@ -1,6 +1,6 @@
 #pragma once
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename... AllCmpts, typename... AnyCmpts, typename... NoneCmpts, typename... Cmpts>
 	EntityQuery::EntityQuery(TypeList<AllCmpts...>, TypeList<AnyCmpts...>, TypeList<NoneCmpts...>, TypeList<Cmpts...>)
 		: filter{ TypeList<AllCmpts...>{}, TypeList<AnyCmpts...>{}, TypeList<NoneCmpts...>{} },
@@ -13,8 +13,8 @@ namespace std {
 	template<typename T>
 	struct hash;
 	template<>
-	struct hash<Ubpa::EntityQuery> {
-		size_t operator()(const Ubpa::EntityQuery& query) const noexcept {
+	struct hash<Ubpa::UECS::EntityQuery> {
+		size_t operator()(const Ubpa::UECS::EntityQuery& query) const noexcept {
 			return query.HashCode();
 		}
 	};
diff --git a/include/UECS/detail/Job.h b/include/UECS/detail/Job.h
index 8a2b19c..2c22773 100644
--- a/include/UECS/detail/Job.h
+++ b/include/UECS/detail/Job.h
@@ -2,7 +2,7 @@
 
 #include "_deps/taskflow/taskflow.hpp"
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	using Job = tf::Taskflow;
 	using JobHandle = tf::Task;
 
diff --git a/include/UECS/detail/RTDCmptTraits.inl b/include/UECS/detail/RTDCmptTraits.inl
index e8b5825..f6dc769 100644
--- a/include/UECS/detail/RTDCmptTraits.inl
+++ b/include/UECS/detail/RTDCmptTraits.inl
@@ -2,7 +2,7 @@
 
 #include "../RTDCmptTraits.h"
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	inline RTDCmptTraits& RTDCmptTraits::Instance() noexcept {
 		static RTDCmptTraits instance;
 		return instance;
diff --git a/include/UECS/detail/RTSCmptTraits.h b/include/UECS/detail/RTSCmptTraits.h
index e11ae29..fde4557 100644
--- a/include/UECS/detail/RTSCmptTraits.h
+++ b/include/UECS/detail/RTSCmptTraits.h
@@ -5,7 +5,7 @@
 #include <unordered_map>
 #include <functional>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	// run-time static component traits
 	class RTSCmptTraits {
 	public:
diff --git a/include/UECS/detail/RTSCmptTraits.inl b/include/UECS/detail/RTSCmptTraits.inl
index 33159a1..8c3a0ae 100644
--- a/include/UECS/detail/RTSCmptTraits.inl
+++ b/include/UECS/detail/RTSCmptTraits.inl
@@ -4,7 +4,7 @@
 
 #include <stdexcept>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	inline size_t RTSCmptTraits::Sizeof(CmptType type) const {
 		assert(sizeofs.find(type) != sizeofs.end());
 		return sizeofs.find(type)->second;
diff --git a/include/UECS/detail/Schedule.inl b/include/UECS/detail/Schedule.inl
index 43ed7b2..ed1f056 100644
--- a/include/UECS/detail/Schedule.inl
+++ b/include/UECS/detail/Schedule.inl
@@ -1,6 +1,6 @@
 #pragma once
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename Func>
 	Schedule& Schedule::Register(Func&& func, std::string name, EntityFilter filter) {
 		Request(std::forward<Func>(func), std::move(name), std::move(filter));
diff --git a/include/UECS/detail/SysFuncGraph.h b/include/UECS/detail/SysFuncGraph.h
index 6e54ab2..ab11297 100644
--- a/include/UECS/detail/SysFuncGraph.h
+++ b/include/UECS/detail/SysFuncGraph.h
@@ -4,7 +4,7 @@
 #include <unordered_set>
 #include <vector>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	class SystemFunc;
 	class SysFuncGraph {
 	public:
diff --git a/include/UECS/detail/SystemFunc.inl b/include/UECS/detail/SystemFunc.inl
index 5055baf..9b30187 100644
--- a/include/UECS/detail/SystemFunc.inl
+++ b/include/UECS/detail/SystemFunc.inl
@@ -2,12 +2,12 @@
 
 #include <_deps/nameof.hpp>
 
-namespace Ubpa::detail::System_ {
+namespace Ubpa::UECS::detail::System_ {
 	template<typename Func>
 	auto Pack(Func&& func) noexcept;
 }
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename Func>
 	SystemFunc::SystemFunc(Func&& func, std::string name, EntityLocator locator, EntityFilter filter)
 		: isJob{ IsEmpty_v<FuncTraits_ArgList<Func>> },
@@ -40,7 +40,7 @@ namespace Ubpa {
 	}
 }
 
-namespace Ubpa::detail::System_ {
+namespace Ubpa::UECS::detail::System_ {
 	template<typename DecayedArgList, typename SortedCmptList>
 	struct Packer;
 
diff --git a/include/UECS/detail/SystemMngr.inl b/include/UECS/detail/SystemMngr.inl
index 908357f..1efbcbe 100644
--- a/include/UECS/detail/SystemMngr.inl
+++ b/include/UECS/detail/SystemMngr.inl
@@ -1,6 +1,6 @@
 #pragma once
 
-namespace Ubpa {
+namespace Ubpa::UECS {
 	template<typename System>
 	void SystemMngr::RegisterOne() {
 		Register(std::string{ nameof::nameof_type<System>() }, &System::OnUpdate);
diff --git a/include/UECS/detail/Util.h b/include/UECS/detail/Util.h
index 6fc2d81..5d4158c 100644
--- a/include/UECS/detail/Util.h
+++ b/include/UECS/detail/Util.h
@@ -3,7 +3,7 @@
 #include <array>
 #include <string_view>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
     static constexpr size_t size_t_invalid = static_cast<size_t>(-1);
 
     inline constexpr size_t hash_combine(size_t x, size_t y) noexcept;
diff --git a/include/UECS/detail/Util.inl b/include/UECS/detail/Util.inl
index f9cc938..5150b04 100644
--- a/include/UECS/detail/Util.inl
+++ b/include/UECS/detail/Util.inl
@@ -2,7 +2,7 @@
 
 #include <UTemplate/TypeID.h>
 
-namespace Ubpa {
+namespace Ubpa::UECS {
     constexpr size_t hash_combine(size_t x, size_t y) noexcept {
         return x ^ (y + 0x9e3779b9 + (x << 6) + (x >> 2));
     }
diff --git a/src/core/Archetype.cpp b/src/core/Archetype.cpp
index 0446b4b..cc7c647 100644
--- a/src/core/Archetype.cpp
+++ b/src/core/Archetype.cpp
@@ -1,6 +1,6 @@
 #include <UECS/detail/Archetype.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 void Archetype::SetLayout() {
diff --git a/src/core/Chunk.cpp b/src/core/Chunk.cpp
index 38853fe..1d6bb1a 100644
--- a/src/core/Chunk.cpp
+++ b/src/core/Chunk.cpp
@@ -2,7 +2,7 @@
 
 #include <UECS/detail/Chunk.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 Chunk::Layout Chunk::GenLayout(const vector<size_t>& alignments, const vector<size_t>& sizes) noexcept {
diff --git a/src/core/EntityFilter.cpp b/src/core/EntityFilter.cpp
index 766620d..69ff967 100644
--- a/src/core/EntityFilter.cpp
+++ b/src/core/EntityFilter.cpp
@@ -1,6 +1,6 @@
 #include <UECS/EntityFilter.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 
 EntityFilter::EntityFilter()
 	: allHashCode{ TypeID<EntityFilter> },
diff --git a/src/core/EntityLocator.cpp b/src/core/EntityLocator.cpp
index 3a14c65..bcdd4b1 100644
--- a/src/core/EntityLocator.cpp
+++ b/src/core/EntityLocator.cpp
@@ -2,7 +2,7 @@
 
 #include <UECS/detail/Util.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 EntityLocator::EntityLocator(set<CmptType> lastFrameCmpts,
diff --git a/src/core/EntityMngr.cpp b/src/core/EntityMngr.cpp
index aa2c750..e879796 100644
--- a/src/core/EntityMngr.cpp
+++ b/src/core/EntityMngr.cpp
@@ -2,7 +2,7 @@
 
 #include <UECS/IListener.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 EntityMngr::~EntityMngr() {
diff --git a/src/core/RTDCmptsView.cpp b/src/core/RTDCmptsView.cpp
index c65859b..e294ea2 100644
--- a/src/core/RTDCmptsView.cpp
+++ b/src/core/RTDCmptsView.cpp
@@ -2,7 +2,7 @@
 
 #include <UECS/EntityLocator.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 RTDCmptsView::Iterator RTDCmptsView::begin() const noexcept {
diff --git a/src/core/Schedule.cpp b/src/core/Schedule.cpp
index c2183b6..22c8e4a 100644
--- a/src/core/Schedule.cpp
+++ b/src/core/Schedule.cpp
@@ -4,10 +4,10 @@
 
 #include <UECS/World.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
-namespace Ubpa::detail::Schedule_ {
+namespace Ubpa::UECS::detail::Schedule_ {
 	struct NoneGroup {
 		NoneGroup() = default;
 		NoneGroup(SystemFunc* func)
diff --git a/src/core/SysFuncGraph.cpp b/src/core/SysFuncGraph.cpp
index 92e8b84..9647b3b 100644
--- a/src/core/SysFuncGraph.cpp
+++ b/src/core/SysFuncGraph.cpp
@@ -6,7 +6,7 @@
 
 #include <cassert>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 bool SysFuncGraph::HaveVertex(SystemFunc* x) const {
diff --git a/src/core/SystemMngr.cpp b/src/core/SystemMngr.cpp
index 759ab01..dc0867c 100644
--- a/src/core/SystemMngr.cpp
+++ b/src/core/SystemMngr.cpp
@@ -2,7 +2,7 @@
 
 #include <UECS/IListener.h>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 
 void SystemMngr::Accept(IListener* listener) const {
 	listener->EnterSystemMngr(this);
diff --git a/src/core/World.cpp b/src/core/World.cpp
index cec9f4f..8599576 100644
--- a/src/core/World.cpp
+++ b/src/core/World.cpp
@@ -2,6 +2,7 @@
 
 #include <UECS/IListener.h>
 
+using namespace Ubpa::UECS;
 using namespace Ubpa;
 using namespace std;
 
diff --git a/src/test/00_basic/main.cpp b/src/test/00_basic/main.cpp
index 46e73d5..441e28b 100644
--- a/src/test/00_basic/main.cpp
+++ b/src/test/00_basic/main.cpp
@@ -1,10 +1,12 @@
 #include <UECS/World.h>
 
+using namespace Ubpa::UECS;
+
 struct Position { float val; };
 struct Velocity { float val; };
 
 struct MoverSystem {
-	static void OnUpdate(Ubpa::Schedule& schedule) {
+	static void OnUpdate(Schedule& schedule) {
 		schedule.Register(
 			[](const Velocity* v, Position* p) {
 				p->val += v->val;
@@ -13,7 +15,7 @@ struct MoverSystem {
 };
 
 int main() {
-	Ubpa::World w;
+	World w;
 	w.systemMngr.Register<MoverSystem>();
 	w.entityMngr.Create<Position, Velocity>();
 	w.Update();
diff --git a/src/test/01_tag/main.cpp b/src/test/01_tag/main.cpp
index 80a1af6..d242df8 100644
--- a/src/test/01_tag/main.cpp
+++ b/src/test/01_tag/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct Data {};
diff --git a/src/test/02_order/main.cpp b/src/test/02_order/main.cpp
index 4f93698..2ef5d17 100644
--- a/src/test/02_order/main.cpp
+++ b/src/test/02_order/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct Data1 {};
diff --git a/src/test/03_query_entity/main.cpp b/src/test/03_query_entity/main.cpp
index c7d5694..2675a48 100644
--- a/src/test/03_query_entity/main.cpp
+++ b/src/test/03_query_entity/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct A {};
diff --git a/src/test/04_filter/main.cpp b/src/test/04_filter/main.cpp
index e7da91a..dcd81e1 100644
--- a/src/test/04_filter/main.cpp
+++ b/src/test/04_filter/main.cpp
@@ -2,6 +2,7 @@
 
 #include <iostream>
 
+using namespace Ubpa::UECS;
 using namespace Ubpa;
 using namespace std;
 
diff --git a/src/test/05_alignment/main.cpp b/src/test/05_alignment/main.cpp
index fc5490c..f5938d9 100644
--- a/src/test/05_alignment/main.cpp
+++ b/src/test/05_alignment/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct alignas(1) A {
diff --git a/src/test/06_none_parallel/main.cpp b/src/test/06_none_parallel/main.cpp
index eebd069..95ef1c1 100644
--- a/src/test/06_none_parallel/main.cpp
+++ b/src/test/06_none_parallel/main.cpp
@@ -2,6 +2,7 @@
 
 #include <iostream>
 
+using namespace Ubpa::UECS;
 using namespace Ubpa;
 using namespace std;
 
diff --git a/src/test/07_overload/main.cpp b/src/test/07_overload/main.cpp
index f192e9f..8d337ce 100644
--- a/src/test/07_overload/main.cpp
+++ b/src/test/07_overload/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct P {};
diff --git a/src/test/08_job/main.cpp b/src/test/08_job/main.cpp
index 5a82984..ad83d08 100644
--- a/src/test/08_job/main.cpp
+++ b/src/test/08_job/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct Data { size_t value; };
diff --git a/src/test/09_idx_in_query/main.cpp b/src/test/09_idx_in_query/main.cpp
index 5e1c938..6a4e817 100644
--- a/src/test/09_idx_in_query/main.cpp
+++ b/src/test/09_idx_in_query/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct A {};
diff --git a/src/test/10_instantiate/main.cpp b/src/test/10_instantiate/main.cpp
index 2da65e4..752ccba 100644
--- a/src/test/10_instantiate/main.cpp
+++ b/src/test/10_instantiate/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct A { float val; };
diff --git a/src/test/11_runtime_cmpt/main.cpp b/src/test/11_runtime_cmpt/main.cpp
index ec69bbe..e7bc77a 100644
--- a/src/test/11_runtime_cmpt/main.cpp
+++ b/src/test/11_runtime_cmpt/main.cpp
@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct RTDSystem {
diff --git a/src/test/12_framegraph/main.cpp b/src/test/12_framegraph/main.cpp
index 46b180a..70afb38 100644
--- a/src/test/12_framegraph/main.cpp
+++ b/src/test/12_framegraph/main.cpp
@@ -2,6 +2,7 @@
 
 #include <iostream>
 
+using namespace Ubpa::UECS;
 using namespace Ubpa;
 using namespace std;
 
diff --git a/src/test/13_performance/main.cpp b/src/test/13_performance/main.cpp
index 2aa8107..2591c80 100644
--- a/src/test/13_performance/main.cpp
+++ b/src/test/13_performance/main.cpp
@@ -1,5 +1,7 @@
 #include <UECS/World.h>
 
+using namespace Ubpa::UECS;
+
 #include <chrono>
 #include <iostream>
 
@@ -7,7 +9,7 @@ struct A { float val; };
 struct B { float val; };
 
 struct TestSystem {
-	static void OnUpdate(Ubpa::Schedule& schedule) {
+	static void OnUpdate(Schedule& schedule) {
 		schedule.Register(
 			[](const A* a, B* b) {
 				// 256 floating-point operations
@@ -20,7 +22,7 @@ struct TestSystem {
 int main() {
 	size_t numEntities = 65536;
 	size_t numUpdate = 144 * 10;
-	Ubpa::World w;
+	World w;
 	w.systemMngr.Register<TestSystem>();
 
 	auto t0 = std::chrono::steady_clock::now();
diff --git a/src/test/14_serialize/main.cpp b/src/test/14_serialize/main.cpp
index 8f2ce3f..28b9821 100644
--- a/src/test/14_serialize/main.cpp
+++ b/src/test/14_serialize/main.cpp
@@ -3,7 +3,7 @@
 
 #include <iostream>
 
-using namespace Ubpa;
+using namespace Ubpa::UECS;
 using namespace std;
 
 struct Position { float val; };