[Information Processing Technician Practical] Key Contents of the 2nd Session in 2021 (1)

※ If there is a source for each content, a link is provided within the related content.

? network

Ad-hoc Network

It has the characteristic of dynamically changing network topology without the need for network devices, and its application areas include emergency rescue, emergency meetings, and military networks in battlefields. It features fast network configuration and low cost.

+ 추가 네트워크 종류

Mesh Network

A new network technology for special purposes such as next-generation mobile communication, home networking, and public safety

USN(Ubiquitous Sensor Network)

A network constructed to wirelessly collect information collected by various sensors, meaning that RFID tags are attached to everything that is needed, and through this, not only object recognition information but also surrounding environmental information is detected and the information is managed by connecting this to the network.

SON(Self Organizing Network)

A network that configures itself according to surrounding conditions

WBAN(Wireless Body Area Network)

Personal area network technology that wirelessly connects wearable or body-implanted sensors or devices

? UX, UI

UX

User Experience, user's emotions or experience

UI

User Interface, user interface, CLI

? 트랜잭션의 특징

The characteristics of transactions include atomicity, consistency, independence, and persistence.

Atomicity - This means that all transactions are reflected in the DB or not.

Consistency - Transaction processing results must always be consistent.

Independence Isolation - When two or more transactions are executing simultaneously, no one transaction can intervene in the operation of another transaction.

Durability - When a transaction is successfully completed, the results must be permanently reflected.

? 정규화

First normalization - Make properties become atomic values!

Second normalization - removes partial function dependencies, i.e. makes it a complete function.

Here, partial functional dependency means preventing a subset of the primary key from being the determinant. For example, if student number and course name are the primary keys, there should be no other columns that can be determined using only the course name.

Third normalization – eliminating transitive dependence.

For example, if a transition relationship is established such as student number ➡ course name ➡ tuition fee, the table is decomposed.

BCNF normalization - ensures that all determinants are candidate keys.

For example, in the relationship between student number, special lecture name, and professor, the primary keys are the student number and special lecture name. Here, it refers to creating two tables so that the student number and special lecture name, which can be the decider, become candidate keys and can be linked to the professor.

? SQL

To modify a tuple, write as follows.

UPDATE 테이블명 SET 컬럼 = 값 WHERE 점수>=90;

? SQL

INNER JOIN

SELECT ... FROM 학생정보 a JOIN 학과정보 b ON a.학과 = b.학과

? Python output

a = 100
result = 0
for i in range(1,3);
result = a >> i
result = result + 1
print(result)

Here, the >> operation is called a shift operator, which is a bitwise operator. The shift operator is an operator that moves bits in binary numbers. > moves the bit to the right.

• Since range(1,3), only 1 and 2 are performed.
• If 100 is expressed in binary, it is 1100100.
• 100>>1 becomes 110010. That is, 50. Then add 1 to get 51.
• Then again, what happens to 100>>2? Move 1100100 2 spaces to the right. 11001 is 25.
• Therefore, 25 plus 1, which is 26, is the correct answer.

The point to note here is that during the shift operation, the value of a does not change to 100.

? AES (Advanced Encryption Standard)

It is an encryption algorithm created by the U.S. National Institute of Standards and Technology (NIST) to replace DES.

The symmetric key encryption method with a 128-bit block size and 128,192,256-bit key size is AES.

? 화이트박스 테스트

Statement Verification Standard Statement Coverage

Design items so that every statement in the source code is performed at least once

Branch verification standards Branch Coverage, Decision coverage

Design items so that every conditional statement in the source code is performed at least once

다중 조건 커버리지 Multiple Condition Coverage

Guarantees 100% coverage by considering all possible logical combinations of all individual conditional expressions within the decision point

Condition Coverage

Items are designed so that each conditional statement in the source code is evaluated as true or false at least once, regardless of the result of the entire conditional expression.

Verification technique more powerful than decision coverage

Brache/Condition Coverage based on quarter/condition

Items are designed to be executed at least once when the results of all conditional statements in the source code and individual conditional expressions included in each conditional statement are true or false.

변형 조건 / 결정 커버리지 Modified Condition/Decision Coverage; MC/DC

Condition/decision coverage is improved by allowing each individual conditional expression to independently affect the result of the overall conditional expression regardless of other individual conditional expressions. Decision coverage is more powerful than condition/decision coverage.

? 블랙박스 테스트

Equivalence Partitioning Testing (=equivalence class decomposition, equal partitioning)

A technique to determine a test case by equalizing the number of normal and abnormal input data and check whether the results matching the input data are output ex) Taking the expected result value when a certain value is input as a test case and checking whether the expected result value is produced when actually tested

Boundary Value Analysis

A technique to select and inspect boundary values ​​as test cases because the probability of errors occurring at boundary values ​​is higher than at the median value of the input conditions.

Cause-Effect Graphing Testing

A technique to systematically analyze influencing situations by analyzing multiple input/output data and then select highly efficient test cases.

Error prediction inspection Error Guessing

Tested by past experience or the sense of a confirmer

Comparison Testing

A testing technique that applies the same test case to multiple versions of a program and compares whether the same results are output.

? SQL

sort output

SELECT ... FROM ... WHERE 이름 LIKE '이%' ORDER BY DESC;

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Source: https://q.fran.kr/%EC%8B%9C%ED%97%98/%EC%A0%95%EB%B3%B4%EC%B2%98%EB%A6%AC%EA%B8%B0%EC%82%AC%20%EC%8B%A4%EA%B8%B0/2021%EB%85%84%202%ED%9A%8C