Okay, I need to create a professional Wikipedia-style document about internal combustion engines (내연기관) under the categories of Technology → Automotive → Engine. Let me start by understanding the user's requirements.

First, the structure: H1 for the title, an overview section, several sections with H2 and H3 headings, and possibly references or related documents. The content needs to be accurate, objective, detailed enough, easy to read, and use technical terms with explanations. Also, markdown formatting is required with proper hierarchy, lists, tables, emphasis, and code blocks if needed. The document should be at least 800 characters long.

Starting with the title: "내연기관" as H1. Then an overview section introducing what internal combustion engines are, their importance in automotive technology. Next sections could include types of engines (like Otto, Diesel), working principles, components, efficiency and environmental impact, modern developments, etc. Each of these can be H2 headings with sub-sections (H3).

For the introduction, I should explain that internal combustion engines convert fuel into mechanical energy through combustion inside the engine. Mention their historical significance and current applications.

In the types section, differentiate between Otto (spark-ignition) and Diesel (compression-ignition) engines. Maybe a table comparing them. Then explain how each works, using H3 headings for each type.

Components: List major parts like cylinder, piston, crankshaft, valves, etc., with brief descriptions. Use bullet points or a table here.

Efficiency and environmental impact: Discuss thermal efficiency, emissions (CO2, NOx), and technologies to reduce them like catalytic converters, EGR, etc. Maybe include some data on efficiency percentages.

Modern developments could cover hybrid systems, alternative fuels, and advancements in engine design. Also mention challenges like emission regulations and the shift towards electric vehicles.

Need to ensure technical terms are explained. For example, "compression-ignition" should be clarified as a process where air is compressed to ignite fuel without a spark plug.

Check for accuracy: Make sure the working principles of both Otto and Diesel engines are correctly described. Mention the four-stroke cycle (intake, compression, power, exhaust) for Otto engines. For Diesel, maybe explain the difference in compression ratio and ignition method.

Include references or related documents at the end, like links to external sources or other articles on automotive technology.

Avoid markdown syntax in my thinking process but ensure it's applied correctly in the final document. Use H1, H2, H3 as specified. Maybe use a table for comparing Otto and Diesel engines. Also, check that each section flows logically and covers necessary details without being too verbose.

Wait, the user mentioned "최소 800자 이상" which is about 800 characters. But in Korean, each character counts, so I need to make sure the total length meets that. However, since it's a document with sections, paragraphs, and lists, it should easily exceed 800 characters.

Double-check for any technical inaccuracies. For example, in Diesel engines, the compression ratio is higher than Otto, leading to higher efficiency but more emissions. Also, mention the role of the spark plug in Otto vs. the high compression in Diesel.

Include terms like "thermal efficiency" and explain them briefly. Maybe add a section on how engine efficiency is measured, such as the Carnot cycle or actual thermal efficiency percentages.

In the modern developments part, discuss technologies like direct injection, turbocharging, variable valve timing, etc., which improve performance and reduce emissions.

Make sure to use clear examples and avoid overly complex sentences. Keep paragraphs concise for readability.

Finally, review the structure: Title, overview, sections with H2/H3, references. Ensure all parts are covered and meet the user's specifications.