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전문가 시스템 _6장_ - 1 서론

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					6. 전문가 시스템

전문가 시스템(Expert Systems)
 특정의 문제를 해결하기 위해 특정의 전문적인 지식을 기
  반으로 실행되는 컴퓨터 시스템
 특정 문제 영역에서 그 영역의 인간 전문가가 의사 결정을
  내리는 것과 유사하게 동작하는 컴퓨터 시스템
 인공지능 분야에서 상업적으로 성공한 대표적 분야

 기능적 측면에서 필요한 요소
       추론 기능
       사용자-시스템 간의 상호작용에 의한 데이터 획득
       결론의 정당성(Justification)
       모듈 구조(Modular architecture)



 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                      Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 전문가 시스템의 배경


    high                                            매우 특화된 프로그램을
                                                     생성하기 위해 좁은
                                                   문제 영역에 대한 고수준의
                                                     정제된 지식을 이용
     PROGRAM POWER




                                        표현 및 탐색 기능을
                                      향상시키는 일반 방법론을
                                       찾고, 특화된 프로그램을
                                          구축하고자 함

                      문제해결을 위한 일반
                     방법론을 찾고, 범용-목적
     low             프로그램을 구축하고자 함


                     1960                   1970               1980

 인공지능: 개념 및 응용         도용태 김일곤 김종완 박창현 공저
                                                   Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




     Breakthrough
          To make a program intelligent, provide it with lots of high-
           quality, specific knowledge about some problem area
     Building    Expert Systems
        Knowledge Engineering: The process of building an expert
         system
        Knowledge Engineer: Expert-system builder
        Need the interaction between the KE and human experts
             – The KE extracts procedures, strategies, and rules of thumb for
               problem solving
             – The KE builds this knowledge into the expert system
          Result: a program that solves problems like the human experts
                    Queries, Problems


           Domain                       Knowledge                                  Expert
           Expert                        Engineer      Strategies,                 System
                                                     Rules-of-thumb,
                                                      Domain rules
                    Answers, Solutions
 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                                    Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 전문가 시스템 구축과정

                             Domain
  Toolbuilder                                                          Extends
                             Expert
                                                                       and tests

         Builds                         Interviews

     Expert
    System                  Knowledge                            Expert
    Building                 Engineer                                                      End-User
                  Uses                           Builds,         System
      Tool                                                                      Uses
                                                 refines,
                                                and tests               Adds
                                                                        data


                                                                 Clerical
                                                                  Staff




 인공지능: 개념 및 응용     도용태 김일곤 김종완 박창현 공저
                                                            Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

Basic Components of Expert System (ES)
 Experts/Knowledge Engineer


 Knowledge Base


 Inference Engine


 User Interface




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                      Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

Basic Concepts of Expert Systems - cont.
 Experts
     Recognizing  and formulating the problem
     Solving the problem quickly and properly
     Explaining the solution
     Learning from experience
     Restructuring knowledge
     Determining relevance

 Expertise is the extensive, task-specific knowledge
   acquired from training, reading and experience
     Theories about the problem area
     Hard-and-fast rules and procedures
     Rules (heuristics)
     Global strategies
     Meta-knowledge (knowledge about knowledge)
     Facts

 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                      Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

Basic Concepts of Expert Systems - cont.
 Transferring Expertise
     Objective    of an expert system
        To transfer expertise from an expert to a computer system and
        Then on to other humans (non-experts)

     Activities
        Knowledge acquisition
        Knowledge representation
        Knowledge inference
        Knowledge transfer to the user

     Knowledge is stored in a knowledge base
     Two knowledge types
          Fact / Procedures(rules)




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                          Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

The Knowledge Engineer
 Helps the expert(s) structure the problem area by
   interpreting and integrating human answers to questions,
   drawing analogies, posing counterexamples, and
   bringing to light conceptual difficulties

 Knowledge Acquisition Subsystem
     Knowledge   acquisition is the accumulation, transfer and
      transformation of problem-solving expertise from experts and/or
      documented knowledge sources to a computer program for
      constructing or expanding the knowledge base

 Usually also the System Builder



 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                          Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

The User
 Possible Classes of Users
    A  non-expert client seeking direct advice - the ES acts as a
      Consultant or Advisor
     A student who wants to learn - an Instructor
     An ES builder improving or increasing the knowledge base -
      a Partner
     An expert - a Colleague or Assistant

 The Expert and the Knowledge Engineer Should
   Anticipate Users' Needs and Limitations When
   Designing ES




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                       Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

Knowledge Base
 The knowledge base contains the knowledge necessary
   for understanding, formulating, and solving problems

 Two Basic Knowledge Base Elements
     Facts
     Special heuristics, or rules that direct the use of knowledge
     Knowledge is the primary raw material of ES
     Incorporated knowledge representation




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                           Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

Inference Engine
 The brain of the ES
 The control structure or the rule interpreter
 Provides a methodology for reasoning
 The computer is programmed so that it can make
  inferences

 Major Element
     Interpreter
     Scheduler
     Consistency    Enforcer




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                      Artificial Intelligence: Concepts and Applications
6. 전문가 시스템

User Interface
 Language processor for friendly, problem-oriented
  communication
 NLP, or menus and graphics


 Explanation subsystem
     Traces  responsibility and explains the ES behavior by
      interactively answering questions
       Why?
       How?
       What?
       (Where? When? Who?)
     Knowledge     Refining System
          Learning for improving performance


 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                                Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 Expert System Building Tool(not the expert system)
             Expert System
             Building Tool

            Expert System
          Building Language
                                      Expert
                                      System
               Support
             Environment




                                                        User


 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                       Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 What Good Are Expert Systems
     Whynot use real Experts?
      → Why do we develop expert systems

          Comparing human and artificial expertise: the good news

                      The Good News
       Human Expertise           Artificial Expertise
       Perishable                Permanent
       Difficult to transfer     Easy to transfer
       Difficult to document     Easy to document
       Unpredictable             Consistent
       Expensive                 Affordable



 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                            Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




     Why    keep a human in the loop?

        Why not eliminate human expert replacing them with expert
         systems?
        Comparing human and artificial expertise: the bad news


                                The Bad News
       Human Expertise                         Artificial Expertise
       Creative                                Uninspired
       Adaptive                                Needs to be told
       Sensory experience                      Symbolic input
       Broad focus                             Narrow focus
       Commonsense knowledge                   Technical knowledge




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                                Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 How Are Expert Systems Organized?
     Organizing     Knowledge
        Knowledge: The information a computer program needs with
         which it can behave intelligently
           
        take the form of facts and rules
        sometimes considers uncertainty



     Many   of rules in expert systems are heuristics
          Comparing Algorithmic with Heuristic methods




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                           Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 The structure of an Expert System
                          Expert System

                        Knowledge Base                         Knowledge
                      (Domain Knowledge)                     Representations

                               Facts
                               Rules



                            Interpreter
                            Scheduler
                       Inference Engine
                   (General Problem-Solving
                          Knowledge)


 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                              Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 Knowledge-Based Systems


               Artificial                         Exhibit intelligent
             Intelligence                        behavior by skillful
              Programs                         application of heuristics


                                              Make domain knowledge
          Knowledge-based                     explicit and separate from
             Systems                            the rest of the system


                  Expert                       Apply expert knowledge
                 Systems                        to difficult, real world
                                                       problems




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                      Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 How Do Expert Systems Differ from Conventional
   Programs

     Comparison       of data processing and knowledge engineering
       Date Processing                   Knowledge Engineering
       Representations and use           Representation and use of
         of data                            knowledge
       Algorithmic                       Heuristic
       Repetitive Process                Inferential process
       Effective manipulation            Effective manipulation of large
         of large data bases                knowledge bases




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                           Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 Basic Characteristics of an Expert Systems
     Characteristicsof an expert system that distinguish it from
      a conventional program

     Expert System

                                       Exhibit expert performance
                  Expertise            Have high level of skill
                                       Have adequate robustness
                                       Represent knowledge symbolically
                  Symbolic reasoning
                                       Reformulate symbolic knowledge
                                       Handle difficult problem domains
                  Depth
                                       Use complex rules
                                       Examine its own reasoning
                  Self-Knowledge
                                       Explain its operation
          Expert Systems sometimes make mistakes
 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                         Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




 What Have Expert Systems Been Used For?
     Basic   Activities of Expert Systems

       Generic Categories
       Category              Problem Addressed
       Interpretation        Inferring situation descriptions from sensor data
       Prediction            Inferring likely consequences of given situations
       Diagnosis             Inferring system malfunctions from observables
       Design                Configuring objects under constraints
       Planning              Designing actions
       Monitoring            Comparing observations to expected outcomes
       Debugging             Prescribing remedies for malfunctions
       Repair                Executing plans to administer prescribed remedies
       Instruction           Diagnosing, debugging, and repairing user
                             behavior
       Control               Governing overall system behavior

 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                                 Artificial Intelligence: Concepts and Applications
6. 전문가 시스템




     Application     Areas for Expert systems
          Chemistry
             – DENDRAL, MOLGEN
          Computer Systems
             – XCON
          Electronics
             – ACE, EURISKO, SOPHIE
          Geology
             – PROSPECTOR
          Medicine
             – MYCIN, ONCOCIN, GUIDON
        Military
        Engineering




 인공지능: 개념 및 응용   도용태 김일곤 김종완 박창현 공저
                                          Artificial Intelligence: Concepts and Applications

				
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posted:5/27/2010
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