Free Practice Questions for Engineer Information Communications

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Key Facts: Engineer Information Communications Exam

100 items

Official written paper length (5 subjects × 20)

KCA Engineer qualification criteria; KCA CQ portal 정보통신기사 portal

150 minutes

Written timing at 30 minutes per subject

KCA written examination rules (과목당 30분)

40 / 60

Written per-subject floor and overall average passing score

National Technical Qualifications Act testing rules

KRW 19,400

Written registration fee on KCA CQ portal

KCA CQ portal fee schedule, checked 2026

KRW 22,600

Practical registration fee on KCA CQ portal

KCA CQ portal fee schedule, checked 2026

2 years

Written-pass exemption period from the pass date

National Technical Qualifications Act Enforcement Decree Article 21

정보통신기사 is KCA's Engineer-grade telecommunications qualification. The 2026 written paper is 100 four-option items in five subjects (20 each, 30 minutes each), with a 40-per-subject and 60-average pass rule, followed by a 2.5-hour written-answer practical in 정보통신 실무. Official fees on KCA CQ portal are KRW 19,400 written and KRW 22,600 practical. OpenExamPrep offers independent English MCQ study for the written topics, not an official translation or practical simulation.

Sample Engineer Information Communications Practice Questions

Try these sample questions to review concepts for the Engineer Information Communications exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1According to the Shannon-Hartley theorem, what is the theoretical maximum channel capacity (C) of a communication channel having a bandwidth of 4 kHz and a signal-to-noise power ratio (S/N) of 31?

A.16 kbps

B.20 kbps

C.24 kbps

D.32 kbps

Explanation: The Shannon-Hartley channel capacity formula is C = B * log2(1 + S/N). Substituting the given parameters: C = 4,000 Hz * log2(1 + 31) = 4,000 * log2(32) = 4,000 * 5 = 20,000 bps = 20 kbps. This represents the absolute theoretical upper bound for error-free data transmission over this noisy channel.

2Using Nyquist's formula for a noiseless channel, what is the maximum theoretical data transmission rate for a channel with a bandwidth of 3 kHz using 8-level discrete signaling (M = 8)?

A.9 kbps

B.12 kbps

C.18 kbps

D.24 kbps

Explanation: Nyquist's maximum data rate theorem for a noiseless channel states that C = 2 * B * log2(M). For B = 3,000 Hz and M = 8 discrete levels, log2(8) = 3 bits per symbol, yielding C = 2 * 3,000 * 3 = 18,000 bps = 18 kbps. This represents the maximum symbol transition rate without intersymbol interference.

3In standard Pulse Code Modulation (PCM, 펄스 부호 변조) for voice telecommunications, what is the standard sampling rate and resulting uncompressed digital bit rate for a single voice channel (DS0)?

A.4,000 samples/sec and 32 kbps

B.8,000 samples/sec and 64 kbps

C.8,000 samples/sec and 128 kbps

D.16,000 samples/sec and 64 kbps

Explanation: Standard telephone speech is bandlimited to 300–3,400 Hz (nominal 4 kHz bandwidth). According to the Nyquist sampling theorem, the minimum sampling frequency must be at least twice the maximum frequency (2 * 4,000 Hz = 8,000 samples/sec). With each sample quantized into 8 bits (256 levels), the resulting bit rate is 8,000 samples/sec * 8 bits/sample = 64 kbps, which forms the fundamental DS0 standard.

4In uniform Pulse Code Modulation (PCM), approximately how much does the theoretical Signal-to-Quantization-Noise Ratio (SQNR) improve when the number of quantization bits per sample is increased from 8 bits to 10 bits?

A.3 dB

B.6 dB

C.12 dB

D.20 dB

Explanation: The theoretical SQNR for uniform quantization of a sinusoidal signal is given by SQNR ≈ 6.02 * n + 1.76 dB, where n is the number of bits per sample. Each additional bit doubles the number of quantization levels, halving the quantization step size (Δ) and reducing quantization noise power by a factor of 4 (6.02 dB). Increasing n from 8 to 10 adds 2 bits, yielding an improvement of approximately 2 * 6.02 dB ≈ 12 dB.

5What is the primary operational characteristic of Manchester encoding (맨체스터 부호화) compared to Non-Return-to-Zero (NRZ) encoding?

A.It halves the required transmission bandwidth by suppressing the carrier frequency

B.It guarantees a mid-bit transition in every bit interval, providing built-in clock synchronization and zero DC component

C.It completely eliminates high-frequency spectral components to reduce cable attenuation

D.It encodes 2 bits per signal symbol to double spectral efficiency

Explanation: Manchester encoding enforces a voltage level transition in the exact middle of every bit interval (e.g., low-to-high for '1' and high-to-low for '0' in IEEE 802.3). This mid-bit transition provides robust self-clocking synchronization for receiver circuitry and eliminates any DC baseline wander, at the cost of requiring twice the baud rate and transmission bandwidth of basic NRZ.

6In T1 carrier digital transmission using Alternate Mark Inversion (AMI), what substitution pattern is inserted by B8ZS (Bipolar with 8-Zero Substitution) when eight consecutive zeros occur?

A.000VB0VB

B.000V10V1

C.B00V00VB

D.00000001

Explanation: B8ZS is a line code designed to maintain pulse density for clock synchronization in North American T1 systems using AMI. When eight consecutive zeros ('00000000') are detected, B8ZS replaces them with '000VB0VB', where 'V' represents a bipolar violation (a pulse having the same polarity as the previous pulse) and 'B' represents a valid bipolar pulse. This intentional violation allows the receiver to detect and reconstruct the eight zeros without losing clock recovery.

7How many bits of information are transmitted per modulation symbol in 16-QAM (Quadrature Amplitude Modulation, 직교 진폭 변조), and how does its theoretical spectral efficiency compare to QPSK (Quadrature Phase Shift Keying)?

A.2 bits/symbol, providing identical spectral efficiency to QPSK

B.4 bits/symbol, providing twice the spectral efficiency of QPSK

C.8 bits/symbol, providing four times the spectral efficiency of QPSK

D.16 bits/symbol, providing sixteen times the spectral efficiency of QPSK

Explanation: The number of bits per symbol in M-ary modulation is given by n = log2(M). For 16-QAM, M = 16, so log2(16) = 4 bits per symbol. Since QPSK has M = 4 and transmits log2(4) = 2 bits per symbol, 16-QAM delivers exactly twice the bits per symbol (4 vs 2), giving it twice the theoretical spectral efficiency (4 bps/Hz vs 2 bps/Hz) for an equivalent symbol rate.

8Why is Gray coding (그레이 부호화) universally employed in constellation point mapping for digital modulation schemes such as QPSK and 16-QAM?

A.It maximizes the Euclidean distance between adjacent signal constellation points

B.It ensures that adjacent signal points differ by only a single binary bit, minimizing the Bit Error Rate (BER) when symbol errors occur

C.It removes the carrier frequency offset in non-coherent detection receivers

D.It compresses the transmitted signal constellation to reduce peak-to-average power ratio (PAPR)

Explanation: In noisy transmission channels, the most probable demodulation error occurs when additive Gaussian noise causes a received symbol to be mistaken for an immediately adjacent constellation point. By assigning bit patterns such that adjacent points differ by only one single bit (Gray coding), a single symbol decision error produces only a single bit error, minimizing the overall Bit Error Rate (BER).

9In Orthogonal Frequency Division Multiplexing (OFDM, 직교 주파수 분할 다중화), what mathematical property allows subcarriers to overlap spectrally without causing Inter-Carrier Interference (ICI)?

A.Subcarriers are separated by guard bands equal to twice the modulation frequency

B.Subcarriers are spaced at frequency intervals of Δf = 1/T (where T is the useful symbol duration), making the integral of their cross-product over time T equal to zero

C.Subcarrier frequencies are selected as prime number multiples of the RF local oscillator

D.Subcarriers are modulated using distinct pseudo-noise spreading codes as in CDMA

Explanation: OFDM achieves high spectral efficiency by placing subcarriers at integer multiples of Δf = 1/T, where T is the symbol duration. Over the observation period T, the mathematical cross-correlation (integral of the product) between any two different subcarriers evaluates to zero. This orthogonality allows the spectra of subcarriers to overlap tightly without causing Inter-Carrier Interference (ICI).

10What is the primary cause of group delay distortion (지연 왜곡) in bandlimited transmission lines, and how is it mitigated?

A.Thermal agitation of electrons; mitigated by cryogenic low-noise amplifiers

B.Variation of signal propagation velocity with frequency across the channel bandwidth; mitigated by transversal equalizers (등화기)

C.Impedance mismatch at terminal connectors; mitigated by directional couplers

D.Non-linear transfer characteristics of power amplifiers; mitigated by baseband clipping

Explanation: Group delay distortion occurs because different frequency components of a composite signal travel through physical transmission media at slightly different phase velocities (dispersion). Consequently, different spectral components arrive at the receiver at different times, spreading pulses and causing Intersymbol Interference (ISI). This is compensated using equalizers (such as transversal filters) that introduce complementary delay characteristics.

About the Engineer Information Communications Exam

Engineer Information Communications (정보통신기사) is South Korea's premier Engineer-grade national technical qualification in telecommunications engineering, administered by the Korea Communications Agency (KCA) under the Ministry of Science and ICT on KCA CQ portal. The written paper uses four-option multiple-choice items across information transmission theory, equipment, networks, systems operation, and computer basics and regulations. After a written pass, candidates sit a 2.5-hour written-answer practical examination in 정보통신 실무. KCA CQ portal publishes the specifications reviewed here in Korean. The questions on this page are independent English-language MCQ study practice for those written topics; they are not an official translation, not a format simulation, and not a substitute for the practical stage.

Exam sponsor: Korea Communications Agency (KCA / 한국방송통신전파진흥원) / Ministry of Science and ICT. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Written paper covering 정보전송일반, 정보통신기기, 정보통신네트워크, 정보시스템운용, and 컴퓨터일반 및 정보설비기준 (20 items and 30 minutes each), followed by a 2.5-hour, 100-point written-answer practical examination in 정보통신 실무. OpenExamPrep study weights below match the five equal written subjects.

Time Limit

150 minutes written; 2.5 hours practical

Passing Score

Written: 40+ per subject floor and 60 average; practical: 60/100

Exam / Certification Fees

KRW 19,400 written / KRW 22,600 practical (KCA CQ portal (cq.or.kr), 2026)

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

KCA CQ portal - Engineer Information Communications (정보통신기사) · Source checked 2026-09-21Official qualification portal operated by Korea Communications Agency (KCA) for ICT qualifications, exam schedules, written/practical fees (KRW 19,400 / KRW 22,600), and test criteria.
KCA National Technical Qualification Grading Criteria · Source checked 2026-09-21Written: four-option MCQ, 20 items per subject, 40-point per-subject floor and 60-point average. Practical: 60/100.
National Technical Qualifications Act Enforcement Decree — 2-year written-pass exemption · Source checked 2026-09-21

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

20%

Information Transmission Fundamentals (정보전송일반)

Transmission lines, analog/digital modulation, multiplexing schemes, Shannon channel capacity, and noise theory.

20%

Information Communications Equipment (정보통신기기)

Terminal devices, digital switching systems, optical transmission components, and RF/wireless equipment.

20%

Information Communications Networks (정보통신네트워크)

OSI reference model, TCP/IP protocol stack, IP routing, LAN/WAN switching, and mobile wireless networks.

20%

Information Systems Operation (정보시스템운용)

Network management systems (NMS/SNMP), traffic engineering, QoS policies, SDN/cloud virtualization, and disaster recovery.

20%

Computer Fundamentals and Regulations (컴퓨터일반 및 정보설비기준)

Computer architecture, operating system fundamentals, Telecommunications Business Act, and Information and Communications Construction Business Act.

Preparing for the Engineer Information Communications Exam

What You Need to Know

Passing score: Written: 40+ per subject floor and 60 average; practical: 60/100
Assessment: Written paper covering 정보전송일반, 정보통신기기, 정보통신네트워크, 정보시스템운용, and 컴퓨터일반 및 정보설비기준 (20 items and 30 minutes each), followed by a 2.5-hour, 100-point written-answer practical examination in 정보통신 실무. OpenExamPrep study weights below match the five equal written subjects.
Time limit: 150 minutes written; 2.5 hours practical
Exam / certification fees: KRW 19,400 written / KRW 22,600 practical (KCA CQ portal (cq.or.kr), 2026) Official sources

Using Our Practice Resources

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Engineer Information Communications: Suggested Study Strategy

1Balance preparation across all five subjects to avoid failing the 40-point per-subject floor (과락), especially in transmission theory and telecom construction regulations.

2Master quantitative formulas: practice Shannon-Hartley capacity calculations, Nyquist rate, optical link budgets (dB/dBm), and IPv4 VLSM subnetting by hand.

3Thoroughly review Korean telecom statutory provisions, including the technical standards for in-building telecommunications facilities (접속설비 기술기준) and engineer qualification grades under the Information and Communications Construction Business Act.

4Treat this English question bank as conceptual drill. Note that the official practical exam (2.5-hour 필답형) requires Korean technical terminology, circuit schematics, and short essay/calculation answers.

Frequently Asked Questions

What is Engineer Information Communications (정보통신기사)?

It is an Engineer-grade National Technical Qualification in telecommunications and network engineering administered by the Korea Communications Agency (KCA) under the Ministry of Science and ICT (MSIT). It qualifies engineers for ICT facility design, supervision (감리), construction, and network operations under Korean law.

How is the official exam structured in 2026?

The written exam consists of 100 four-option multiple-choice items divided into five subjects (20 items each) taken over 150 minutes (30 minutes per subject). Scoring requires at least 40 points in every subject and a 60-point overall average. After passing, candidates take a 2.5-hour written-answer practical exam (필답형) in 정보통신 실무 (Information Communications Practice) requiring at least 60 points to pass.

Who administers the exam, and is it on Q-Net or the KCA CQ portal?

Unlike most general engineering certifications administered by HRD Korea on Q-Net, 정보통신기사 is administered by the Korea Communications Agency (KCA / 한국방송통신전파진흥원) on its dedicated portal CQ (www.cq.or.kr).

What are the 2026 fees and written timing?

As listed on KCA CQ portal for 2026, the written examination fee is KRW 19,400 and the practical examination fee is KRW 22,600. The written paper allocates 30 minutes per subject, totaling 150 minutes for all five subjects.

What language is the official exam, and what is this bank?

KCA publishes and administers the official examination in Korean. This practice bank is an independent English-language MCQ study adaptation designed for technical review of the written syllabus topics. It is not an official translation, CBT replica, or practical examination simulation.