Microsoft MVP성태의 닷넷 이야기
글쓴 사람
정성태 (techsharer at outlook.com)
홈페이지
첨부 파일
 
(연관된 글이 1개 있습니다.)

C# - 닷넷 응용 프로그램에서 DB2 Express-C 데이터베이스 사용 (3) - ibmcom/db2express-c 컨테이너 사용

지난 글에서는,

C# - 닷넷 응용 프로그램에서 DB2 Express-C 데이터베이스 사용 (2)
; https://www.sysnet.pe.kr/2/0/1408

윈도우에 생성한 DB2 환경을 예로 들었는데 이번에는 docker에 이미 설치된 ("ibmcom/db2express-c"에서 이름이 바뀐) "ibmcom/db2" 컨테이너로 예를 들겠습니다. 이를 위해 db2 환경이 실행 중인 컨테이너 내에 bash를 실행시켜 들어갑니다.

# docker ps  | grep db2
a3cf35df65ba db2_db "/entrypoint.sh db2s…"   5 months ago  Up 13 days  22/tcp, 0.0.0.0:50000->50000/tcp  db2_db_1

// ibmcom/db2express-c 이미지가 실행 중인 컨테이너 ID: a3cf35df65ba

# docker exec -it a3cf35df65ba /bin/bash

그래도 혹시 모르니 db2가 적절하게 설치되었는지 db2val을 찾아,

# find / -name db2val
/home/db2inst1/sqllib/bin/db2val

확인해 보고,

# /home/db2inst1/sqllib/bin/db2val
DBI1379I  The db2val command is running. This can take several minutes.

DBI1335I  Installation file validation for the DB2 copy installed at
      /home/db2inst1/sqllib was successful.

DBI1343I  The db2val command completed successfully. For details, see
      the log file /tmp/db2val-200305_062706.log.

이후 db2 실행 파일을 찾아 DB 제어를 위한 명령행 환경으로 진입합니다.

# find / -name db2
/home/db2inst1/sqllib/bin/db2
...[생략]...

# /home/db2inst1/sqllib/bin/db2
...[생략]...

db2 =>

db2 명령행까지 들어왔다면 이제 게임 끝이군요, (아래의 예는 생성된 DB 목록을 조회하는 것으로) 여타 DB 관리처럼 이후 진행을 하면 됩니다.

db2 => list db directory

 System Database Directory

 Number of entries in the directory = 1

Database 1 entry:

 Database alias                       = MYTESTDB
 Database name                        = MYTESTDB
 Local database directory             = /home/db2inst1
 Database release level               = 10.00
 Comment                              =
 Directory entry type                 = Indirect
 Catalog database partition number    = 0
 Alternate server hostname            =
 Alternate server port number         =

여기까지 해서 컨테이너의 TCP 매핑, Database 이름을 구했으면 IBM.Data.DB2.dll의 DB2Connection 객체에 사용할 연결 문자열이 다음과 같이 구해집니다.

Server=testdbsrv:50000;Database=MYTESTDB;UID=...;PWD=...

이후의 제어는 그냥 편안하게 "IBM Data Studio"를 이용해 원격에서 제어하시는 것도 ^^ 좋겠습니다.




이제 환경 구성하면서 오류가 발생한 상황을 정리해 보겠습니다. 우선, DB2Connection.Open에서 다음과 같은 오류가 발생한다면?

Server Error in '/' Application.
SQL1159  Initialization error with DB2 .NET Data Provider, reason code 2, tokens C:\Test\WebApp\bin\db2app64.dll, , Process Owner: TESTAD\TESTUSR
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: SQL1159  Initialization error with DB2 .NET Data Provider, reason code 2, tokens C:\Test\WebApp\bin\db2app64.dll, , Process Owner: TESTAD\TESTUSR

Source Error:

Line 48:             {
Line 49:                 connection.ConnectionString = connectionString;
Line 50:                 connection.Open();
Line 51: 

Source File: C:\Test\WebApp\DB2Default.aspx.cs    Line: 50

Stack Trace:

[InvalidOperationException: SQL1159  Initialization error with DB2 .NET Data Provider, reason code 2, tokens C:\Test\WebApp\bin\db2app64.dll, , Process Owner: TESTAD\TESTUSR]
   IBM.Data.DB2.DB2ConnPool.Open(DB2Connection connection, String& szConnectionString, DB2ConnSettings& ppSettings, Object& ppConn) +7637
   IBM.Data.DB2.DB2Connection.Open() +577
   WebApp.DB2Default.Page_Load(Object sender, EventArgs e) in C:\Test\WebApp\DB2Default.aspx.cs:50
   System.Web.UI.Control.OnLoad(EventArgs e) +108
   System.Web.UI.Control.LoadRecursive() +90
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1607

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4075.0}

해당 프로젝트가 빌드된 /bin 폴더에 db2app64.dll 파일이 없기 때문입니다.




IBM Data Studio에서 db2 서버의 주소, 데이터베이스, 계정 명과 비밀번호를 입력 후 "Test Connection"을 했는데 다음과 같은 오류가 발생한다면?

A connection attempt was unsuccessful.

Summary

SQL4499N  A fatal error occurred that resulted in a disconnect from the data source.

Try the following suggestions to help solve the problem:

Ensure that the data server has been started.
Check that the database name used is the actual database name and not an alias name.
Check that the host is a valid name or IP address, and that the port number is valid for communication with the data server.
To further diagnose the problem, return to the Properties section and use the Tracing page to enable tracing. Contact the database administrator and provide the trace and other support information available.
Full message content: [jcc][t4][2057][11264][4.14.113] 응용프로그램 서버(AS)가 연결을 거부했습니다. 
찾을 수 없거나 트랜잭션을 지원하지 않은 TESTDB 데이터베이스에 액세스하려고 시도했습니다.

Explanation

<b>Explanation:</b><br/><br/>An attempt was made to access a database that was not found, has not been started, or does not support transactions.
<br/><b>User response:</b><br/><br/>Ensure that the specified database name exists in the system database directory. If the database name does not exist in the system database directory, either the database does not exist or the database name has not been cataloged. If needed, issue a db2start command and then resubmit the current command.
SQLSSTATE: 08004

Support

Connection Properties

Database : TESTDB
URL :  jdbc:db2://192.168.100.50:50000/TESTDB:retrieveMessagesFromServerOnGetMessage=true;securityMechanism=4;
User name : TESTUSR
Password : (Not Shown)

Environment

Driver class name = com.ibm.db2.jcc.DB2Driver
Driver version = 4.14.113
Driver JAR file path = C:\Program Files\ibm\SDPShared\plugins\com.ibm.datatools.db2_2.1.503.v20121002_1809\driver\db2jcc4.jar;C:\Program Files\ibm\SDPShared\plugins\com.ibm.datatools.db2_2.1.503.v20121002_1809\driver\db2jcc_license_cisuz.jar
Operating system name = Windows Server 8
Operating system architecture = amd64
Operating system version = 6.2
JVM implementation vendor = IBM Corporation
JVM runtime = Java(TM) SE Runtime Environment
Java version = JRE 1.7.0 IBM J9 2.6 Windows Server 8 amd64-64 20120809_118929 (JIT enabled, AOT enabled)
J9VM - R26_Java726_SR2_20120809_0948_B118929
JIT  - r11.b01_20120808_24925
GC   - R26_Java726_SR2_20120809_0948_B118929
J9CL - 20120809_118929
Launcher = C:\Program Files\ibm\DS3.2.0\eclipse.exe

Stack Trace

com.ibm.db2.jcc.am.DisconnectNonTransientConnectionException: [jcc][t4][2057][11264][4.14.113] 응용프로그램 서버(AS)가 연결을 거부했습니다. 
찾을 수 없거나 트랜잭션을 지원하지 않은 TESTDB 데이터베이스에 액세스하려고 시도했습니다.  ERRORCODE=-4499, SQLSTATE=08004com.ibm.db2.jcc.am.ed.a(Unknown Source)
com.ibm.db2.jcc.am.ed.a(Unknown Source)
com.ibm.db2.jcc.t4.y.u(Unknown Source)
com.ibm.db2.jcc.t4.y.n(Unknown Source)
com.ibm.db2.jcc.t4.y.a(Unknown Source)
com.ibm.db2.jcc.t4.y.a(Unknown Source)
com.ibm.db2.jcc.t4.b.c(Unknown Source)
com.ibm.db2.jcc.t4.b.b(Unknown Source)
com.ibm.db2.jcc.t4.b.b(Unknown Source)
com.ibm.db2.jcc.t4.b.a(Unknown Source)
com.ibm.db2.jcc.t4.b.a(Unknown Source)
com.ibm.db2.jcc.t4.b.a(Unknown Source)
com.ibm.db2.jcc.t4.b.<init>(Unknown Source)
com.ibm.db2.jcc.DB2SimpleDataSource.getConnection(Unknown Source)
com.ibm.db2.jcc.DB2SimpleDataSource.getConnection(Unknown Source)
com.ibm.db2.jcc.DB2Driver.connect(Unknown Source)
com.ibm.db2.jcc.DB2Driver.connect(Unknown Source)
org.eclipse.datatools.connectivity.drivers.jdbc.JDBCConnection.createConnection(Unknown Source)
org.eclipse.datatools.connectivity.DriverConnectionBase.internalCreateConnection(Unknown Source)
org.eclipse.datatools.connectivity.DriverConnectionBase.open(Unknown Source)
org.eclipse.datatools.enablement.ibm.db2.internal.luw.JDBCLUWConnectionFactory.createConnection(Unknown Source)
org.eclipse.datatools.connectivity.internal.ConnectionFactoryProvider.createConnection(Unknown Source)
org.eclipse.datatools.connectivity.internal.ConnectionProfile.createConnection(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.NewDatabaseConnnectionWizardPage.handleTestConnection(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.NewDatabaseConnnectionWizardPage.access$6(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.NewDatabaseConnnectionWizardPage$10.handleEvent(Unknown Source)
org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
org.eclipse.jface.window.Window.runEventLoop(Unknown Source)
org.eclipse.jface.window.Window.open(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.actions.NewDBConnectionHandler.execute(Unknown Source)
org.eclipse.ui.internal.handlers.HandlerProxy.execute(Unknown Source)
org.eclipse.core.commands.Command.executeWithChecks(Unknown Source)
org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(Unknown Source)
org.eclipse.ui.internal.handlers.HandlerService.executeCommand(Unknown Source)
org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(Unknown Source)
org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(Unknown Source)
org.eclipse.ui.menus.CommandContributionItem.handleWidgetSelection(Unknown Source)
org.eclipse.ui.menus.CommandContributionItem.access$19(Unknown Source)
org.eclipse.ui.menus.CommandContributionItem$5.handleEvent(Unknown Source)
org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
org.eclipse.ui.internal.Workbench.runEventLoop(Unknown Source)
org.eclipse.ui.internal.Workbench.runUI(Unknown Source)
org.eclipse.ui.internal.Workbench.access$4(Unknown Source)
org.eclipse.ui.internal.Workbench$7.run(Unknown Source)
org.eclipse.core.databinding.observable.Realm.runWithDefault(Unknown Source)
org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Unknown Source)
org.eclipse.ui.PlatformUI.createAndRunWorkbench(Unknown Source)
org.eclipse.ui.internal.ide.application.IDEApplication.start(Unknown Source)
org.eclipse.equinox.internal.app.EclipseAppHandle.run(Unknown Source)
org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(Unknown Source)
org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(Unknown Source)
org.eclipse.core.runtime.adaptor.EclipseStarter.run(Unknown Source)
org.eclipse.core.runtime.adaptor.EclipseStarter.run(Unknown Source)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.eclipse.equinox.launcher.Main.invokeFramework(Unknown Source)
org.eclipse.equinox.launcher.Main.basicRun(Unknown Source)
org.eclipse.equinox.launcher.Main.run(Unknown Source)
org.eclipse.equinox.launcher.Main.main(Unknown Source)

데이터베이스 (위의 메시지에서는 TESTDB)가 실제로 있는지 확인할 필요가 있습니다.




또는, 다음과 같이 오류가 발생한다면?

A connection attempt was unsuccessful.

Summary

SQL4214N  A connection authorization failure has occurred.

Try the following suggestions to help solve the problem:

Ensure that the user name and password are correct. These values are defined in the New Connection wizard or, for an existing connection, on the General page in the Driver Properties section.
Ensure that the user name is valid. For example, on UNIX and Linux platforms, user names must be all lowercase. <a href="http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/index.jsp?topic=/com.ibm.db2.luw.admin.dbobj.doc/doc/c0007245.html">Review the DB2 general naming rules</a>.
If you recently changed permissions on critical DB2 files, such as db2ckpw, or moved to a new fix pack, the db2iupdt command that updates the instance might not have been run. Contact your DBA to run db2iupdt with the InstName parameter to update the instance.
Full message content: [jcc][t4][201][11237][4.14.113] 연결 권한 부여에 실패했습니다. 이유: 보안 메커니즘이 지원되지 않습니다.

Explanation

<b>Explanation:</b><br/><br/>An error occurred during security processing. Either the user name specified or the password specified, or both, are invalid.
<br/><b>User response:</b><br/><br/>Ensure that the specified user name and password are correct.
SQLSSTATE: 28000

Support

Connection Properties

Database : MYTESTDB
URL :  jdbc:db2://192.168.100.50:50000/MYTESTDB:retrieveMessagesFromServerOnGetMessage=true;securityMechanism=4;
User name : TESTUSR
Password : (Not Shown)

Environment

Driver class name = com.ibm.db2.jcc.DB2Driver
Driver version = 4.14.113
Driver JAR file path = C:\Program Files\ibm\SDPShared\plugins\com.ibm.datatools.db2_2.1.503.v20121002_1809\driver\db2jcc4.jar;C:\Program Files\ibm\SDPShared\plugins\com.ibm.datatools.db2_2.1.503.v20121002_1809\driver\db2jcc_license_cisuz.jar
Operating system name = Windows Server 8
Operating system architecture = amd64
Operating system version = 6.2
JVM implementation vendor = IBM Corporation
JVM runtime = Java(TM) SE Runtime Environment
Java version = JRE 1.7.0 IBM J9 2.6 Windows Server 8 amd64-64 20120809_118929 (JIT enabled, AOT enabled)
J9VM - R26_Java726_SR2_20120809_0948_B118929
JIT  - r11.b01_20120808_24925
GC   - R26_Java726_SR2_20120809_0948_B118929
J9CL - 20120809_118929
Launcher = C:\Program Files\ibm\DS3.2.0\eclipse.exe

Stack Trace

com.ibm.db2.jcc.am.SqlInvalidAuthorizationSpecException: [jcc][t4][201][11237][4.14.113] 연결 권한 부여에 실패했습니다. 이유: 보안 메커니즘이 지원되지 않습니다. ERRORCODE=-4214, SQLSTATE=28000com.ibm.db2.jcc.am.ed.a(Unknown Source)
com.ibm.db2.jcc.am.ed.a(Unknown Source)
com.ibm.db2.jcc.am.ed.a(Unknown Source)
com.ibm.db2.jcc.t4.b.f(Unknown Source)
com.ibm.db2.jcc.t4.b.a(Unknown Source)
com.ibm.db2.jcc.t4.y.b(Unknown Source)
com.ibm.db2.jcc.t4.y.a(Unknown Source)
com.ibm.db2.jcc.t4.y.a(Unknown Source)
com.ibm.db2.jcc.t4.b.c(Unknown Source)
com.ibm.db2.jcc.t4.b.b(Unknown Source)
com.ibm.db2.jcc.t4.b.b(Unknown Source)
com.ibm.db2.jcc.t4.b.a(Unknown Source)
com.ibm.db2.jcc.t4.b.a(Unknown Source)
com.ibm.db2.jcc.t4.b.a(Unknown Source)
com.ibm.db2.jcc.t4.b.<init>(Unknown Source)
com.ibm.db2.jcc.DB2SimpleDataSource.getConnection(Unknown Source)
com.ibm.db2.jcc.DB2SimpleDataSource.getConnection(Unknown Source)
com.ibm.db2.jcc.DB2Driver.connect(Unknown Source)
com.ibm.db2.jcc.DB2Driver.connect(Unknown Source)
org.eclipse.datatools.connectivity.drivers.jdbc.JDBCConnection.createConnection(Unknown Source)
org.eclipse.datatools.connectivity.DriverConnectionBase.internalCreateConnection(Unknown Source)
org.eclipse.datatools.connectivity.DriverConnectionBase.open(Unknown Source)
org.eclipse.datatools.enablement.ibm.db2.internal.luw.JDBCLUWConnectionFactory.createConnection(Unknown Source)
org.eclipse.datatools.connectivity.internal.ConnectionFactoryProvider.createConnection(Unknown Source)
org.eclipse.datatools.connectivity.internal.ConnectionProfile.createConnection(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.NewDatabaseConnnectionWizardPage.handleTestConnection(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.NewDatabaseConnnectionWizardPage.access$6(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.NewDatabaseConnnectionWizardPage$10.handleEvent(Unknown Source)
org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
org.eclipse.jface.window.Window.runEventLoop(Unknown Source)
org.eclipse.jface.window.Window.open(Unknown Source)
com.ibm.datatools.connection.internal.ui.databases.actions.NewDBConnectionHandler.execute(Unknown Source)
org.eclipse.ui.internal.handlers.HandlerProxy.execute(Unknown Source)
org.eclipse.core.commands.Command.executeWithChecks(Unknown Source)
org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(Unknown Source)
org.eclipse.ui.internal.handlers.HandlerService.executeCommand(Unknown Source)
org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(Unknown Source)
org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(Unknown Source)
org.eclipse.ui.menus.CommandContributionItem.handleWidgetSelection(Unknown Source)
org.eclipse.ui.menus.CommandContributionItem.access$19(Unknown Source)
org.eclipse.ui.menus.CommandContributionItem$5.handleEvent(Unknown Source)
org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
org.eclipse.ui.internal.Workbench.runEventLoop(Unknown Source)
org.eclipse.ui.internal.Workbench.runUI(Unknown Source)
org.eclipse.ui.internal.Workbench.access$4(Unknown Source)
org.eclipse.ui.internal.Workbench$7.run(Unknown Source)
org.eclipse.core.databinding.observable.Realm.runWithDefault(Unknown Source)
org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Unknown Source)
org.eclipse.ui.PlatformUI.createAndRunWorkbench(Unknown Source)
org.eclipse.ui.internal.ide.application.IDEApplication.start(Unknown Source)
org.eclipse.equinox.internal.app.EclipseAppHandle.run(Unknown Source)
org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(Unknown Source)
org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(Unknown Source)
org.eclipse.core.runtime.adaptor.EclipseStarter.run(Unknown Source)
org.eclipse.core.runtime.adaptor.EclipseStarter.run(Unknown Source)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.eclipse.equinox.launcher.Main.invokeFramework(Unknown Source)
org.eclipse.equinox.launcher.Main.basicRun(Unknown Source)
org.eclipse.equinox.launcher.Main.run(Unknown Source)
org.eclipse.equinox.launcher.Main.main(Unknown Source)

접속 계정의 ID나 비밀번호를 다시 체크해 볼 필요가 있습니다.




[이 글에 대해서 여러분들과 의견을 공유하고 싶습니다. 틀리거나 미흡한 부분 또는 의문 사항이 있으시면 언제든 댓글 남겨주십시오.]

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by SeongTae Jeong, mailto:techsharer at outlook.com

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11669정성태8/24/201813644개발 환경 구성: 394. 윈도우 환경에서 elasticsearch의 한글 블로그 검색 인덱스 구성
11668정성태8/24/201824415오류 유형: 478. 윈도우 업데이트(KB4458842) 이후 SQL Server 서비스 시작 오류
11667정성태8/24/201812620오류 유형: 477. "Use Unicode UTF-8 for worldwide language support" 옵션 설정 시 SQL Server 2016 설치 오류 [1]
11666정성태8/22/201812364사물인터넷: 37. 아두이노 - 코딩으로 대신하는 오실레이터 회로의 소리 출력파일 다운로드1
11665정성태8/22/201813996사물인터넷: 36. 오실레이터 회로 동작을 아두이노의 코딩으로 구현하는 방법파일 다운로드1
11664정성태8/22/201813771개발 환경 구성: 393. 윈도우 환경에서 elasticsearch의 한글 형태소 분석기 설치 [1]
11663정성태8/22/201816224개발 환경 구성: 392. 윈도우 환경에서 curl.exe를 이용한 elasticsearch 6.x 기본 사용법
11662정성태8/21/201811404사물인터넷: 35. 병렬 회로에서의 커패시터파일 다운로드1
11661정성태8/21/201813058사물인터넷: 34. 트랜지스터 동작 - 컬렉터-이미터 간의 저항 측정파일 다운로드1
11660정성태8/19/201812001사물인터넷: 33. 세라믹 커패시터의 동작 방식파일 다운로드1
11659정성태8/19/201811574사물인터넷: 32. 9V 전압에서 테스트하는 PN2222A 트랜지스터파일 다운로드1
11658정성태8/18/201814698사물인터넷: 31. 커패시터와 RC 회로파일 다운로드3
11657정성태8/18/201812785사물인터넷: 30. 릴레이(Relay) 제어파일 다운로드3
11656정성태8/16/20189882사물인터넷: 29. 트랜지스터와 병렬로 연결한 LED파일 다운로드1
11655정성태8/16/201811497사물인터넷: 28. 저항과 병렬로 연결한 LED파일 다운로드1
11654정성태8/15/201812047사물인터넷: 27. 병렬 회로의 저항, 전압 및 전류파일 다운로드1
11653정성태8/14/201812969사물인터넷: 26. 입력 전압에 따른 LED의 전압/저항 변화 [1]파일 다운로드1
11652정성태8/14/201811090사물인터넷: 25. 컬렉터 9V, 베이스에 5V와 3.3V 전압으로 테스트하는 C1815 트랜지스터파일 다운로드1
11651정성태8/14/201815566사물인터넷: 24. 9V 전압에서 테스트하는 C1815 트랜지스터 [1]파일 다운로드3
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