Extending work without plagiarism I am working in a sub-field of computer science (deep learning), more specifically a particular application of LSTMs to learn simple functions. My work is building on the work of another researcher to an extent that I am using the same model, parameters and problem definition. I am writing a research paper based on my findings.

My work is different in the sense that I am introducing some different concepts from another area and trying to make a generalisation about the very nature of ANNs (using his work as an intermediary). And since his work is the only such publication till now, I am taking some things directly in my work eg. Problem Definition or Model.

So the question is whether it will count as plagiarism? If yes then how can I circumvent it as I have to write many things as it is, there's no other way to get around that as I am using them as it is.
Plagiarism is passing someone else's work off as your own. As long as your paper makes clear exactly what is new and what is borrowed from previous work, and cites the previous work accordingly, there is no danger of plagiarism.