2026년 3회 전기기사 l 필기 복원 특강 l 김상훈 교수님 LIVE

Main ideas & lessons (what the speaker conveys)

• Purpose of the “restoration” lecture: help students review and reorganize what they’ve studied for the 3rd Electrician (전기기사) written exam, rather than “just look at notes and move on.”
• How to access practice/CBT:
  • The CBT (engineer app site) becomes available at 6:00 PM.
  • If it doesn’t show up right now, wait until 6 PM.
• Exam strategy emphasized throughout:
  • Many questions are repeat/modified versions of past finals.
  • Focus on units, formula familiarity, and careful reading of what has changed:
    • variables swapped
    • constants missing
    • exponents changed
    • small notation/condition changes
  • Even when problems feel “new,” they often come from previous question patterns with minor edits.
  • For the exam: master the finals reviews first, then fill weaknesses with older material (often 3–7 years, depending on the subject).
• Overall outlook:
  • The speaker predicts the exam will be harder due to modifications and newly included items, including reworked old problems and some additions.

---

Methodology / instructions presented (detailed)

CBT / learning logistics

• Use the CBT on the engineer app website after the lecture ends.
• Check at exactly 6 PM (CBT “opens” then).
• Treat other CBTs similarly; the speaker mentions equivalence with the next industrial engineer CBT schedule.

How to solve magnetics/electromagnetics questions (recurring tactics)

• Use unit analysis (“unit battle”)
  • When stuck, verify what the answer should be dimensionally (e.g., conversions involving W/m³, current density, conductivity, etc.).
• Don’t assume the “old problem” applies without checking the change
  • The speaker repeatedly warns that questions may be “the same” but with small modifications, such as:
    • dielectric type differences (e.g., mica vs. glass)
    • factor/exponent changes
    • variable convention changes (uppercase/lowercase)
    • missing symbol (e.g., ε₀)
    • sides/conditions swapped
• Remember key conceptual definitions
  • Examples mentioned: pyroelectricity, Ampère’s law in cylindrical coordinates, Maxwell stress direction, Faraday/Lenz induced EMF, characteristic impedance, etc.
• Boundary-condition / wave / magnetic circuit logic
  • For boundary conditions and waves: determine which side has higher/lower permittivity and how that changes refraction/incidence angle logic.
  • For magnetic circuits with air gaps/voids: handle carefully using geometry lengths and permeability relations.

Study plan guidance near the end

• First review the finals:
  • “Basically review the finals first.”
• Then expand by weakness:
  • If you’re weak in certain subjects, review up to 5–7 years.
  • Suggested starting range for many topics: around 3 years.
• Practical exam preparation:
  • Check the speaker’s “secret tips” for the practical exam and review the finals.

---

Content overview: what topics were walked through

(The lecture is essentially a walkthrough of many multiple-choice “restoration” problems. Numeric details are partly unclear in places, but the topic coverage is consistent.)

Electromagnetics / magnetics (questions ~1–20 region)

• Capacitors with dielectrics
  • Relative permittivity effects
  • Adjusting voltage to match charge
• Power density calculations
  • Includes “optimal power per unit” / W/m³-style questions
• Radiation / electromagnetic constants and formulas
  • Includes relationships involving λ (wavelength-related values)
• Pyroelectricity
  • Heating/cooling crystals (tourmaline)
• Electron motion in uniform magnetic field
  • Circular motion radius dependencies on B and speed
• Boundary conditions and wave propagation
  • Correct/incorrect logic based on permittivity side and refraction/incidence relation
• Maxwell stress direction
  • Effect described as moving “from larger dielectric/material side to smaller side” (as stated)
• Magnetic circuit with air gap (void)
  • Uses μ, gap/iron core lengths; emphasis on tricky choice logic
• Magnetic energy / energy density type computation
  • Emphasizes converting the formula into correct units
• “Fantasy solenoid” style problems
  • Use given current, turns/geometry, and inductance-type reasoning

Continued technical electrical topics (mid section: devices & installations)

• Circular solenoid inductance / wave / grounding / conductors
  • Includes hemispherical grounding grade
  • Includes cylindrical-conductor field/unfolding potential-style problems
• Capacitor energy
  • Highlights common confusion between units/representations (e.g., “joule/calorie”-style misapplication)
• Scaling / exponent sensitivity
  • Demonstrates effects like doubling currents leading to i²-type changes
• Ampère’s law in cylindrical coordinates
  • Notes the non-standard nature of some interpretations; reminds to use the correct cylindrical form
• Faraday–Lenz induced EMF and notation
  • Warns about using the given n correctly and sign/convention placement
• Electric field / charge differentiation
  • Repeated differentiation logic and choosing the correct negative exponent outcome

Power engineering / electrical power installation / control engineering (later region)

Power engineering

• Notes that many written-final questions are identical except for one change (e.g., “condenser loss” mentioned).
• Mentions short-circuit capacity on the supply side / circuit breaker context.

DC systems & losses

• Voltage fluctuation power loss in a two-wire DC system.

Transmission / impedance concepts

• Characteristic impedance
• Wave-impedance-like reasoning logic.

Grounding (multiple grounding)

• Reasons for electrically connecting conductors
  • mentions “high/low compression” (as stated in the subtitles)

Electrical devices and machines

• DC generator
  • Parallel operation conditions
• Transformer connection
  • Y vs. modified Y via inserted winding
  • Phase/rated voltage interpretation
• Induction motor starting slip
  • Full torque condition
  • Slip-ring resistor counting clarified (confusion resolved)
• Regenerative braking
  • Not for emergencies
  • Commercial-mode requirement

Control engineering

• Transfer/feedback block diagram reasoning
  • individual feedback vs indirect feedback distinction
• Laplace / characteristic equation
  • root placement in the s-plane
• Tracking vs regulation
  • tracking described as “target changes over time”
• Controller gain reasoning
  • integrator / first-order support factor logic
  • differentiating gain relationships

Equipment standards (many questions near the end: ~82–100 range)

• The speaker claims these are largely included in the final document and emphasizes checking:
  • Cable rules (e.g., 400V or less → specific coefficient/value)
  • Mechanical protection vs no protection values
  • Support line intervals
  • Rooftop burn cost
  • Regenerative braking rules
  • Minimum height/coverage-type values
  • Grounding and safety factor references (mentions 2.5)
  • Mentions “medical supply” and movement path type items (wording is noisy in subtitles, but they are referenced)

---

Sources / speakers featured

• Kim Sang-hun (김상훈 교수님) — main lecturer and speaker throughout.
• Jongno Academy (종로 아카데미 / 종로) — referenced as the offline class provider.
• Engineer app site / CBT platform — referenced as the CBT delivery source.
• General references to textbooks/finals materials, but no specific book authors are named in the subtitles.

---