[CS Technical Interview 6] Java and Object-Oriented Programming that gets you talking

A course where you can understand core network concepts and train to explain them verbally for interviews.

A course where you understand core operating system concepts and train to explain them verbally for interviews.

A course that helps you understand core concepts of computer architecture and trains you to explain them verbally in interviews.

A course where you can understand core data structure concepts and train to explain them verbally for interviews.

A course that helps you understand core database concepts and trains you to explain them verbally in interviews.

A course where you understand core JavaScript concepts and train to explain them verbally for interviews.

A course where you understand core JavaScript concepts and train to explain them verbally for interviews.

Learn Java programming language by solving 100 problems. The entire course consists of 5 parts. In this course, Part 5, you will solve problems on topics such as certification (COS Pro Level 2), collections, and generic concepts.

A course where you understand core operating system concepts and train to explain them verbally for interviews.

You will learn Java's concurrency mechanisms and multithreading techniques in depth and acquire the knowledge and skills necessary to solve various parallel processing problems that you may encounter in practice. Starting from basic thread management, you will learn advanced synchronization techniques, how to use thread pools, and Java's concurrency-related classes in depth.

This is a [Backend, Resume Enhancement] class prepared for job seekers and junior developers.

You've probably written SQL using JdbcTemplate before, right? Everyone has likely had that experience of sighing while having to fix both the SQL and the RowMapper every time a single column changes. This course starts from that very pain. Doing a single SELECT with pure JDBC takes 35 lines. You open a Connection, create a PreparedStatement, iterate through the ResultSet, and if you miss a single close(), the server crashes. After typing through this hell yourself, when you finally encounter a single line of JPA's save(), you'll feel "this is why we use JPA" not just in your head, but in your hands.

DevOps Interview Preparation: Master your interview preparation for Git, Docker, CI/CD, Terraform, Ansible, Kubernetes, and Monitoring.

This course was created based on my personal experience passing the very first revised Information Processing Engineer practical exam, which had a pass rate of only 5.34%. The Information Processing Engineer practical exam can no longer be prepared for through simple memorization alone. In particular, the ability to read the execution flow of C, Java, Python, and SQL code to track results, as well as the ability to accurately distinguish short-answer concepts and write them as answers, has become crucial. This course is structured to help even beginners who are new to programming follow along step-by-step, covering everything from creating variable tables to tracking C, Java, Python, and SQL code, core practical terminology, and written exam subjects 1 through 5. Rather than being a video-centered course, this is a text-based course designed for fast reading and repeated review. It makes it easy to look up necessary parts again and focuses on practicing how to derive answers at the testing center by following the code and explanations directly. The 1st update covers the practical programming sections: C, Java, Python, and SQL. The 2nd update will organize core terms and concepts required for the short-answer practical questions and provide a "Stepper Simulator" to practice code tracking directly. The 3rd update will sequentially expand to cover written exam subjects 1 through 5. The Stepper Simulator is designed so that you don't just stop at reading explanations; you can understand how variable values change as the code executes line by line by following along yourself. If you have any questions while taking the course, please leave them in the Q&A. I will respond as quickly as possible to ensure your learning doesn't get stuck.

A course that helps you understand core database concepts and trains you to explain them verbally in interviews.

A course where you can understand core network concepts and train to explain them verbally for interviews.

If you use JS but find it difficult to explain why it works, this course provides the answer. From execution context, closures, and the event loop to Promise concurrency, prototypes, Virtual DOM, memory leaks, and bundle optimization—you won't just read about 18 chapters of advanced JS concepts; you'll learn by seeing them happen right before your eyes with a simulator. Code-based quizzes are provided for every chapter, and you can own it for life for the price of a single chicken dinner.

This course is a process of learning the basic theories of data structures by directly implementing them using JAVA programming. It is designed to go beyond simply learning theory, allowing you to gain a deeper understanding of the principles of data structures by implementing them with actual code. Learners will theoretically study core data structure concepts such as arrays, stacks, queues, lists, trees, and graphs, while simultaneously experiencing the actual operation process by implementing them in JAVA code. Through this, you can develop logical thinking and problem-solving skills rather than simple rote learning, and enjoy the synergistic effect of mastering both programming and data structures together. 👉 Upon completing this course, learners will master the basic concepts and structural characteristics of data structures, as well as the ability to implement and apply them in real-world development environments, building a foundation for designing more efficient and robust programs.

Refactoring is one of the basic skills that a software engineer should have. This course is designed to explain and practice various code smells and refactoring techniques in a more practical way using IntelliJ and Java.

Learn the essential modern Java technologies of Lambda, Stream, and functional programming with Java, from the basics to the practical level, in depth.

"Simply knowing technology well does not make you a good sales engineer." Understanding customers’ problems, connecting technology to business value, and exerting influence between sales and development are the core responsibilities of a sales engineer. In this course, drawing on more than 20 years of B2B software presales experience, I will systematically share practical know-how on customer meetings, requirements analysis, demos, PoCs, proposal strategies, and internal collaboration. Learn the work frameworks and mindset of a sales engineer that you can apply immediately in practice.

You can systematically learn stock trading automation using Python and the Interactive Brokers API, which holds the top spot in global market share.

If you want to understand game engines, building one yourself is the fastest way. This is a project-based course where you will implement the core structure of a console game engine using C++ and complete projects including Sokoban and a flight shooting game. It provides a perspective that allows for a deep understanding of the structures of the Unreal and Unity engines.

After using it for 14 days starting immediately upon release, here are the reasons why I recommend Claude Code (AI Coding) to everyone—from job seekers to industry professionals—as something they can apply right away.

This course allows you to experience a comprehensive list of questions and answer strategies for both technical and behavioral interviews. In particular, the curriculum is designed to help you prepare for interviews by learning—through Q&A—server scaling strategies and large-scale data processing strategies essential for junior-level technical interviews, as well as how to provide the best answers to open-ended questions typically encountered in final interviews.

A course that helps you understand core concepts of computer architecture and trains you to explain them verbally in interviews.