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Key Facts: Engineer Motor Vehicles Maintenance Exam

100 items

Written CBT question count (5 subjects × 20)

Q-Net Engineer qualification standard

150 minutes

Written CBT duration (30 min per subject)

Q-Net examination timetable

40 / 60

Written passing threshold (40 floor per subject, 60 overall average)

HRD Korea grading regulations

KRW 19,400

Written exam registration fee

Q-Net jmCd=1070 fee schedule (2026)

KRW 64,600

Practical exam registration fee

Q-Net jmCd=1070 fee schedule (2026)

2 years

Written pass exemption validity

National Technical Qualifications Act Enforcement Decree Art. 21

자동차정비기사 is HRD Korea's engineer-grade automotive technical qualification. The written CBT comprises 100 four-option questions across 5 subjects (20 items each in 150 minutes total), requiring at least 40 points per subject and a 60 overall average. The practical combines a 90-minute written-answer component (50 points) and approximately 6 hours of work-type tasks (50 points). Official fees are KRW 19,400 written and KRW 64,600 practical.

Sample Engineer Motor Vehicles Maintenance Practice Questions

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

1Within the elastic range of a steel connecting rod, which relation is Hooke's law (훅의 법칙) for uniaxial loading?

A.Shear stress is proportional to the cube of shear strain

B.Strain energy is always equal to the product of Poisson's ratio and volume

C.Stress is independent of strain once yield begins

D.Normal stress is proportional to normal strain (σ = Eε), with E the modulus of elasticity (탄성계수)

Explanation: Hooke's law (훅의 법칙) states that, in the linear elastic range, uniaxial normal stress is proportional to normal strain: σ = Eε. The constant E is Young's modulus (탄성계수). Engineer-level 일반기계 items use this as the starting constitutive relation before yield, not as a plastic or shear-cube rule.

2For a closed thermodynamic system (밀폐계) that contains a fixed mass of working fluid, which statement is the first law (열역학 제1법칙)?

A.Net heat transfer into the system minus net work done by the system equals the change in internal energy (Q − W = ΔU, with the sign convention that W is work out)

B.Entropy of every process is identically zero

C.Heat can flow spontaneously from a colder body to a hotter body without work input

D.Pressure times volume is always a conserved mass

Explanation: The first law for a closed system is energy conservation: heat added minus work done by the system equals the rise in stored internal energy, Q − W = ΔU (many Korean texts use this heat-in/work-out convention). It does not require reversible processes and does not replace the second law's entropy statement.

3Air in an engine intake manifold may be treated as an ideal gas (이상기체). Which equation of state is used?

A.p = constant, independent of temperature

B.u = pv only, with no temperature dependence

C.pV = mRT (or p = ρRT), with T the absolute temperature

D.h = u − pV for every real gas

Explanation: An ideal gas obeys pV = mRT, equivalently p = ρRT, with T in kelvin. Internal energy of a calorically perfect ideal gas depends only on temperature, which is a separate constitutive statement from the equation of state.

4A steel bar is pulled in tension and becomes slightly thinner. What material property (푸아송비) describes this lateral contraction?

A.Bulk modulus as the ratio of hydrostatic pressure to volumetric strain only

B.Coefficient of thermal expansion α = ε / ΔT under uniaxial stress

C.Shear modulus G as the ratio of bending moment to curvature

D.Poisson's ratio ν = −ε_lateral / ε_axial, typically near 0.3 for steels

Explanation: Poisson's ratio (푸아송비) is ν = −ε_lateral / ε_axial in uniaxial tension or compression. Structural steels are typically near ν ≈ 0.27–0.30 in the elastic range, so a tensile rod contracts laterally while elongating axially.

5On a p–V diagram, heat is added first at constant volume and then at constant pressure, followed by isentropic expansion and constant-volume heat rejection. Which air-standard cycle (공기표준 사이클) is this?

A.Otto cycle (오토 사이클) only — heat addition is entirely at constant volume

B.Diesel cycle (디젤 사이클) only — heat addition is entirely at constant pressure

C.Carnot cycle (카르노 사이클) — two isotherms and two isentropes

D.Sabathé / dual cycle (사바테 사이클, 복합 사이클) — mixed constant-volume and constant-pressure heat addition

Explanation: The Sabathé or dual cycle (사바테 사이클, 복합 사이클) models mixed combustion: part of the heat addition at constant volume (like Otto) and part at constant pressure (like Diesel). It is the usual air-standard idealization of a high-speed diesel with a finite ignition delay followed by a burning period.

6Which statement is a correct form of the second law of thermodynamics (열역학 제2법칙) for engines and heat flow?

A.A cyclic heat engine cannot convert heat from a single reservoir entirely into work with no other effect (Kelvin–Planck); equivalently, heat does not flow unaided from a colder body to a hotter body (Clausius)

B.Q − W = ΔU is itself the second law

C.Entropy of an isolated system must decrease in every real process

D.A real engine may exceed Carnot’s η = 1 − TL/TH between the same two reservoirs

Explanation: The second law sets the direction of processes: not all energy is available as work, and isolated-system entropy does not decrease. Kelvin–Planck and Clausius statements are equivalent. The first law (Q − W = ΔU) is energy accounting and does not forbid a 100% heat-to-work engine; the second law does.

7A cantilever beam of length L = 0.80 m carries a concentrated end load F = 800 N. The rectangular cross-section is b = 30 mm by h = 40 mm (h is the depth in the load plane). Using σ = My/I with I = bh³/12, what is the maximum bending stress at the built-in end?

A.40 MPa

B.60 MPa

C.80 MPa

D.160 MPa

Explanation: The fixing moment is M = FL = 800 × 0.80 = 640 N·m. For the rectangle, I = bh³/12 = 0.030 × (0.040)³ / 12 = 1.60 × 10⁻⁷ m⁴ and y_max = h/2 = 0.020 m. Then σ = My/I = 640 × 0.020 / 1.60 × 10⁻⁷ = 80 × 10⁶ Pa = 80 MPa at the outer fibers of the root.

8A solid circular drive shaft has diameter d = 40 mm and transmits torque T = 200 N·m. Using the torsion formula τ = Tr/J with J = πd⁴/32, what is the maximum shear stress?

A.7.96 MPa

B.63.7 MPa

C.31.8 MPa

D.15.9 MPa

Explanation: J = π(0.040)⁴ / 32 = 2.513 × 10⁻⁷ m⁴ and r = 0.020 m. Then τ_max = Tr/J = 200 × 0.020 / 2.513 × 10⁻⁷ = 15.9 MPa at the outer surface. Equivalently τ_max = 16T / (πd³).

9An engineer wants an air-standard Otto-cycle (오토 사이클) efficiency of 60% with γ = 1.4. Using η = 1 − 1/r^(γ−1), what compression ratio r is required?

A.About 9.9 : 1

B.About 2.5 : 1

C.About 6.3 : 1

D.About 15.6 : 1

Explanation: Rearrange 0.60 = 1 − 1/r^0.4, giving r^0.4 = 1/(1 − 0.60) = 2.5. Therefore r = 2.5^(1/0.4) = 2.5^2.5 ≈ 9.88, or about 9.9 : 1. This is an ideal air-standard result, not a prediction of an actual engine's brake efficiency.

10For an air-standard Diesel cycle (디젤 사이클), compression ratio r and γ are held constant while cutoff ratio ρ is increased above 1. What happens to thermal efficiency?

A.It decreases because more heat is added later in the expansion process

B.It increases without limit as the cutoff ratio grows

C.It remains constant because efficiency depends only on compression ratio

D.It immediately becomes equal to Carnot efficiency

Explanation: At fixed r and γ, increasing the cutoff ratio extends constant-pressure heat addition farther into the expansion stroke. The cutoff factor (ρ^γ − 1)/[γ(ρ − 1)] increases, so the subtracted term in the Diesel-cycle efficiency expression grows and thermal efficiency falls. This comparison holds within the ideal air-standard model.

About the Engineer Motor Vehicles Maintenance Exam

Engineer Motor Vehicles Maintenance (자동차정비기사) is South Korea's engineer-grade national technical qualification in automotive engineering, maintenance, and vehicle safety inspection, administered by HRD Korea under the Ministry of Land, Infrastructure and Transport (MOLIT). The written CBT tests mechanics and thermodynamics, engines, chassis, electrical/electronic systems, and statutory vehicle inspection. Passing candidates advance to the composite practical: 90 minutes of written-answer diagnosis and approximately 6 hours of hands-on maintenance/inspection work. The questions on this page are an independent English-language MCQ study adaptation by OpenExamPrep; they are not an official translation or format simulation.

Exam sponsor: HRD Korea (Q-Net) / Ministry of Land, Infrastructure and Transport (MOLIT). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Written paper: 100 four-option items divided into 5 subjects (일반기계 및 열역학, 자동차엔진, 자동차섀시, 자동차전기, 자동차검사; 20 items and 30 minutes each, 150 minutes total). Practical: 90-minute written-answer diagnostics (50 points) plus approximately 6 hours of hands-on maintenance/inspection work (50 points) in 자동차정비·검사 실무.

Time Limit

150 minutes for written CBT (30 minutes per subject); practical: 90 minutes written-answer plus approximately 6 hours work-type

Passing Score

Written: at least 40 points in each subject (과락 40점) and a 60-point overall average out of 100; Practical: 60 points or more out of 100

Exam / Certification Fees

KRW 19,400 written / KRW 64,600 practical (total KRW 84,000)

Exam sponsor website

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

Official sources

Q-Net Engineer Motor Vehicles Maintenance (자동차정비기사) exam page (jmCd=1070) · Source checked 2026-09-20Official Korean and English qualification titles, MOLIT oversight, HRD Korea administration, written fee KRW 19,400, practical fee KRW 64,600, and 출제기준 coverage.
Q-Net national technical qualification grading method (Engineer grade) · Source checked 2026-09-20Written: 100 four-option CBT MCQs across 5 subjects, passing mark 40+ per subject and 60 average. Practical: 60/100.
Q-Net written-exam timetable (기사·산업기사 과목별 30분) · Source checked 2026-09-20Official timing allocation of 30 minutes per subject, totaling 150 minutes for 5 subjects.
National Technical Qualifications Act Enforcement Decree — 2-year written-pass exemption · Source checked 2026-09-20Article 21 provides a two-year exemption from the written examination following an initial written pass.
Korea Motor Vehicle Management Act (자동차관리법) & Enforcement Rules · Source checked 2026-09-20Current statutory inspection standards in [별표 15] (제73조), including brakes, side-slip, lighting-condition checks, and speedometer indication error of +25% / −10% measured at 40 km/h.

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%

General Mechanics & Thermodynamics (일반기계 및 열역학)

Mechanics of materials (stress-strain, bending stress, beam deflection, shear stress, torsion formula, Mohr's circle), thermodynamic laws (1st and 2nd laws, enthalpy, entropy), ideal gas equations, and air-standard cycles (Otto, Diesel, Sabathé, Carnot, Brayton).

20%

Automobile Engine (자동차엔진)

Real engine cycles, IMEP/BMEP, thermal and mechanical efficiency, heat balance, combustion stoichiometry and lambda, knock dynamics, advanced valvetrain (CVVT, CVVD, Atkinson/Miller cycles), GDI fuel spray dynamics, turbocharging/VGT matching, and diesel aftertreatment (DOC, DPF, SCR, LNT).

20%

Automobile Chassis (자동차섀시)

Vehicle dynamics, tire friction ellipse, slip angle and cornering stiffness, understeer gradient, suspension kinematics, ECS, MDPS/EPS control, dynamic braking axle load transfer, EBD, ESC yaw moment control, planetary gear trains (Simpson, Ravigneaux, Lepelletier), DCT hydraulics, and e-LSD.

20%

Automobile Electrical Systems (자동차전기)

Power semiconductors, ECU microcontrollers, sensor signal processing (Hall effect, inductive, magnetoresistive, piezo, zirconia, wideband A/F), multiplex networks (CAN 2.0B, CAN FD, LIN, FlexRay, Automotive Ethernet), EV/HEV architectures (P0-P4, BEV), IPMSM traction motors, inverters, LDC, and BMS.

20%

Automobile Inspection (자동차검사)

Motor Vehicle Management Act inspection standards, periodic/comprehensive inspections, tuning approval, roller brake tester limits (total >= 50% of 공차중량, parking >= 20%, same-axle left-right difference <= 8%), side-slip tester (<= 5 mm/m), current lighting-condition checks, speedometer indication error within +25% / −10% at 40 km/h, and exhaust emission testing.

Preparing for the Engineer Motor Vehicles Maintenance Exam

What You Need to Know

Passing score: Written: at least 40 points in each subject (과락 40점) and a 60-point overall average out of 100; Practical: 60 points or more out of 100
Assessment: Written paper: 100 four-option items divided into 5 subjects (일반기계 및 열역학, 자동차엔진, 자동차섀시, 자동차전기, 자동차검사; 20 items and 30 minutes each, 150 minutes total). Practical: 90-minute written-answer diagnostics (50 points) plus approximately 6 hours of hands-on maintenance/inspection work (50 points) in 자동차정비·검사 실무.
Time limit: 150 minutes for written CBT (30 minutes per subject); practical: 90 minutes written-answer plus approximately 6 hours work-type
Exam / certification fees: KRW 19,400 written / KRW 64,600 practical (total KRW 84,000) Official sources

Using Our Practice Resources

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Engineer Motor Vehicles Maintenance: Suggested Study Strategy

1Master mechanical and thermodynamic formulas: commit beam bending stress (sigma = M*y/I), torsion formula (tau = T*r/J), and thermal efficiency equations for Otto, Diesel, and Sabathé cycles to memory.

2Practice engine performance calculations: regularly compute indicated and brake mean effective pressures (IMEP/BMEP), brake specific fuel consumption (bsfc), and volumetric efficiency.

3Understand chassis and braking dynamics: derive dynamic axle load transfer during deceleration, calculate planetary gear ratios using tabular methods, and study tire lateral slip angle dynamics.

4Memorize periodic-inspection limits in 자동차관리법 시행규칙 [별표 15] (제73조 관련): total service-brake force at least 50% of 공차중량, same-axle left-right difference within 8% of that axle load, parking brake at least 20% of vehicle weight, side-slip within 5 mm per metre, and speedometer indication error within +25% / −10% measured at 40 km/h.

Frequently Asked Questions

What is Engineer Motor Vehicles Maintenance (자동차정비기사)?

It is South Korea's highest-tier national technical qualification in automotive maintenance and inspection, certified by HRD Korea under MOLIT. It certifies engineering-level competence in automotive mechanical design, thermodynamics, powertrain analysis, advanced chassis dynamics, EV/HEV systems, and vehicle inspection regulations.

How is the official examination structured in 2026?

The written exam is a 150-minute CBT consisting of 100 four-choice questions across five 20-question subjects: 일반기계 및 열역학, 자동차엔진, 자동차섀시, 자동차전기, and 자동차검사. Candidates need at least 40 points in every subject and a 60-point overall average. The practical is composite: a 90-minute written-answer component worth 50 points plus an approximately 6-hour work-type component worth 50 points.

What are the eligibility requirements for the Engineer grade?

Q-Net provides several eligibility routes. Common examples include a relevant 4-year university degree (or expected graduation), Industrial Engineer (산업기사) plus 1 year of relevant experience, Craftsman (기능사) plus 3 years, 4 years of relevant work, or another qualification accepted in the same or a similar field. Relevant 2- and 3-year college routes are also available with the experience Q-Net specifies; candidates should complete the official eligibility self-check.

How long does a passing written exam score remain valid?

A passing written exam result remains valid for 2 years from the date of the pass announcement under Article 21 of the National Technical Qualifications Act Enforcement Decree, allowing candidates to attempt the practical examination during that period without re-taking the written paper.

What are the official fees for the exam in 2026?

According to official Q-Net listings, the written CBT fee is KRW 19,400 and the practical examination fee is KRW 64,600, totaling KRW 84,000.