Posts

English editions of every public post.

깨달음 리스트 Find the Use Before the Technology
What I learned from trying to anchor exploration in technology first: deep tech and technical moats become real value only after meeting problems and users.
Founder Notes 기술보다 쓰임새를 먼저 찾자 (Founder Note)
기술보다 쓰임새와 문제를 먼저 찾아야 실제 가치와 딥테크로 이어진다는 기록.
깨달음 리스트 Find the Use Before the Technology
A reflection on finding real problems and use cases before pursuing deep tech and technical moats.
깨달음 리스트 Say What I Want Instead of Giving the Answer They Want
A reflection on repeating what I want instead of giving the answer someone else is trying to elicit, without treating persuasion as an obligation.
깨달음 리스트 When Someone's Words Make Me Doubt Myself
A reflection on questioning guilt-driven self-doubt and preserving the right to speak, ask, and choose for myself.
깨달음 리스트 The Courage to Say No Without Guilt
What I learned about saying no and making decisions by owning my feelings and judgment instead of being pulled by logic or social framing.
깨달음 리스트 What to Decide Before the Next Project
A reflection on choosing a long-term technological thesis while building products today and compounding durable technical, customer, and ecosystem advantages.
AI & Agents When I Read AI’s Long Answers, My Own Thinking Disappears
AI helps me uncover what I don’t know, but when I follow along with a long answer, average advice can take the place of my own thinking. I need to narrow my questions and make the judgment myself.
Founder Notes Zorba Is a Free Man
While reading 《Zorba the Greek》, I reflect on the meaning of freedom. I felt that simply living as one wishes is not enough; it also requires the courage to bear the consequences of one’s choices and not run away from oneself. Rather than searching for the right answer, I think about a life in which I make what I have chosen into the right answer.
Founder Notes When I Was in Elementary School, I Wanted to Become Tony Stark
I look back on the things I wanted to build as a child and my longing to program. I conclude that what kept me from starting was less a lack of ability than not knowing how to search, ask questions, and learn. After imagining a different life, I arrive at the conclusion that I can make the choices I couldn't make back then now.
Founder Notes How I Set Up My First Content Calendar
My first content calendar and publishing guidelines for running a blog consistently.
Founder Notes A Realistic Way to Look at Blog Advertising Revenue
Realistic criteria to know first when expecting advertising revenue from a new blog.
Founder Notes A Newsletter Is the Smallest System for Creating Fans
Why newsletters, unlike search traffic, create fans of a blog.
Founder Notes How to Do SEO Without Losing Your Voice
Criteria for preparing for search visibility without letting your writing become a mechanical summary.
Build Log Why I Write Build Logs
Why an ongoing build log matters more than a completed retrospective.
Build Log What I Learned While Deploying a Blog with Cloudflare Pages
A summary of the deployment structure I worked out while hosting a blog on Cloudflare Pages instead of a laptop server.
Founder Notes The Structure That Makes People Come Back to a Blog
I’ve organized a structure for creating readers who come back, rather than a blog focused only on views.
Build Log How This Blog Was Built
A structure for building an Astro blog based on a template and deploying it to Cloudflare Pages.
Founder Notes What I Will Document Publicly Over the Next 100 Days
I organized the topics and operating approach for the posts I will publish on my blog over 100 days.
Founder Notes Why Am I Starting to Document Publicly?
The first record in building an audience that follows my journey—not a blog focused solely on attracting search traffic.
Data & ML HalluLens Paper Review
Forget hallucination benchmarks plagued by concerns about existing data leakage!
Programming & CS pyimage1 doesn't exist error
Problem summary: When `AutoComplete.autocomplete()` is executed in `main.py`, the PostgreSQL connection displays a success message, but the actual data retrieval (`User.get_random_meme()`) does not work, or the GUI raises an error (`pyimage1 doesn't
Programming & CS What is daemon?
In computing, a daemon is a program that runs as a background process, rather than being under the direct control of an interactive user.
Programming & CS What is a POMDP?
POMDP
Data & ML batch vs batch size
A bundle of data samples—the number of samples contained in one batch
Data & ML The Concepts of Embeddings and Tokenization
Dividing a sequence (such as text or f0 audio divided into frames) into tokens, quantifying them, and mapping them through indexing; arranging those tokens based on their semantic associations
Data & ML Tensor Manipulation Tips - What is unsqueeze?
unsqueeze is a function in PyTorch that adds a new dimension (an axis of length 1) to a tensor. For example, if the shape of quantized_f0 is (1703,), quantized_f0.unsq
Data & ML What is nn.Embedding
Motivation\nMy understanding of the concept of embedding is that natural language or entities are numerically placed in an embedding space according to the semantic similarity desired by the user.\n\nBut rather than passing natural-language lyrics directly through nn.Embedding, are the lyrics already v
Data & ML Why do we transpose when using nn.Embedding?
The shape after summing the lyrics encoder and melodyU encoder is (1, 192, 1) - (b, h, time(seq_len)). These undergo FFT operations again in the enhanced condition encoder, but likewise nn
Data & ML Mean pooling - Let's match the embedding dimensions
\nProblem\nFFT encoding Lyrics and the quantized f0 melody produces [batch size, hidden channel, time(seq_len) -> sequence length].\nThe sequence lengths might be different, right??\n\nSolution\nm
Programming & CS Python getter → What Is __getitem__?
`__getitem__` is a method in Python that is called when an object is indexed (`obj[key]`) or sliced (`obj[start:stop]`). Defining this method inside a class allows instances of that class to be used like lists or dictionaries. 📌 Basic Usage 🎯 Key Features When `obj[key]` is called, `obj.__getitem__(key)` is called automatically....
Programming & CS How to Map a Func to Elements of Multiple Nested Data Structures
Create nest_map https://dotiromoook.tistory.com/28
Programming & CS Stack -> Finding the Minimum Value
Two arrays: stack and min_stack. The stack is implemented as is, while min_stack repeatedly assigns the minimum value to each index whenever the stack is updated. The stack is implemented using an Int index called top as a cursor. Odd-numbered indexes are stack, and even-numbered indexes are min_stack.
Programming & CS Interpretation of Bayes' Theorem
This is the author's interpretation, so please point out any mistakes! Probability from a Bayesian perspective: a concept of predicting future 'possibilities,' that is, future uncertainty, based on existing evidence (clues that have already occurred, expressed as probabilities) and a hypothesis(). (Induction)\\-> Existing: regarding specific events
Programming & CS Expected Value vs. Mean: Why Do LLM Papers Use Expected Value?
Expected value: a value calculated based on probabilities to predict the future; a prediction of possible future outcomes (induction—judgment predicting the future based on experience, observation, and evidence) Mean: a value calculated from existing data from a frequentist perspective; a definite value based on data that has already been observed (deduction—based on data that is already known
Build Log How Do You Trust AI Answers?
\bAI Answer Fact-Checker: cluehunter
Programming & CS What It Means for a Model to Learn
I only learned this recently, so please let me know if there are any errors. A series of processes for adjusting a model’s weight values. The model has learned the “method” of converting relationships among words or the meaning of sentences into vectors.
Programming & CS Bayes' Theorem
Bayes' theorem is a law of probability used to infer the cause after an event has occurred. It is used in the process of updating a model's probability when new data is provided.
Programming & CS If a Problem Only Tells You That A and B Are Dependent, Without Giving the Intersection Probability or Conditional Probability
Before the LLM era, I had questions in high school but could not formulate them clearly, so I ended up lost in a maze. What should I do if a problem does not provide the probability of an intersection or a conditional probability, and only tells me that A and B are dependent without directly giving a conditional probability?
Founder Notes 2024 Memoir
With less than 2 hours left until 2024 ends, I want to do this year's review that I've been putting off and putting off.
Data & ML Overfitting with k-fold cross-validation
Hyperparameter tuning and CV overfitting
Programming & CS What is a class method? How do you access methods of a nested class from a nested class?
The reason for using a class method rather than an instance method when using methods in a nested class stems from the relationship between the nested class and the outer class and the differences in how instance methods and class methods work. A nested class (nested class) is an outer
Founder Notes The Importance of Terms
Terms are important. The meaning I attach to a term and the meaning someone else attaches to it can be vastly different. To resolve this, it is necessary to have an understanding of agreed-upon terms when communicating with people in a new field. However, rather than taking an approach like memorizing an English dictionary in order to learn a new field
Programming & CS (NumPy Broadcasting) Why do the values come out strange when scoring in NumPy?
In structured data modeling, there was a very large difference between scoring the entire dataset and scoring by stratification when scoring. Calculation error. One shape is a pandas Series, and the other is a pandas DataFrame. The difference between a 2D array and a 1D
Founder Notes How to Benchmark 2023 Korean CSAT with LLMs
🔧 How to Benchmark 2023 Korean CSAT with LLMs We’ve developed experimental code for benchmarking the 2023 Korean CSAT Language section. Use this to estimate the performance of your desired models be...
Founder Notes o1-preview Achieves 97 Points on the 2025 Korean CSAT Language Section!
csat eng.ver
Build Log How to Benchmark an LLM on the CSAT
How many points can my model score on the CSAT?
Build Log o1-preview Achieves 97 Points on the 2025 CSAT Korean Language Section
The end of the human era has arrived
Data & ML How to Identify Outliers
https://esj205.oopy.io/72782730-23e4-43cf-8799-f3cdcbcb57b9
Data & ML What Is a Quartile? (What Is a Box Plot?)
Whisker plot
Programming & CS Error When Validating GPT Analysis with a JSON Schema
Even when I define the JSON schema I want, GPT sometimes fails to extract it correctly. In this case, you can set the item of a property that is allowed to have a null value to ["string", "null"].
Programming & CS ModuleNotFoundError: No module named 'modAL' Unfair nonsense
Uninstall and reinstall
Programming & CS Explaining OpenAI Async Processing: The GOAT
https://python.useinstructor.com/blog/2023/11/13/learn-async/
Programming & CS Results Don't Come Out in Order in Async
The results of asynchronous processing come out all jumbled!!
Programming & CS How Asynchronous Processing Works
How Asynchronous Processing Works
Programming & CS OSError: [Errno 8] Exec format error: '/Users/naya/.wdm/drivers/chromedriver/mac64/127.0.6533.88/chromedriver-mac-arm64/THIRD_PARTY_NOTICES.chromedriver'\n
Chrome driver getting unfairly blamed
Programming & CS What Is an Environment Variable?
A variable that maintains state in the background behind a running program. Since it is dynamic, it can be changed during execution.
Programming & CS When You Shouldn't Use load_dotenv
When you need to load multiple API keys, they may get mixed up.
Data & ML Multilabel Classification Fine-Tuning
Experimental design evaluation metric macro
Founder Notes Let’s Spend More Time on What the Problem Is
The most important process for finding a solution
Founder Notes How Do You Learn a New Concept? (How to Learn Top-Down)
How do you do top-down learning?
Programming & CS Design Pattern in ML (Asynchronous pattern)
Reference 1\\. Reference for the GOAT ml design pattern summary: https://github.com/mercari/ml-system-design-pattern/blob/master/README_ko.md
Programming & CS Reflections on a Semester of Surviving Linux
Linux Torvalds
Programming & CS linux Survival D-12 (Docker Installation)
Docker, let’s go
Programming & CS Linux Survival Log D-11 (Installing PyCharm)
Let's go, PyCharm
Programming & CS Linux Survival Log D-8 (MongoDB Installation)
When I participated in an open-source RAG project, the database used for RAG was MongoDB. Since connecting to the database was not my task, I did not have the opportunity to do it myself, but after installing and using it directly on Linux during “Living with Linux for a Semester,” I came up with the idea that I would use it right away whenever I had an interesting project idea
Programming & CS Linux Survival Log D-7 (Installing Slack)
Install Slack
Programming & CS Linux Survival Log D-6 (Git Installation)
Version control, let's go
Programming & CS linux Survival Log D-5 (Installing DVC (Data Version Control))
Data version control
Programming & CS Linux Survival Log D-4 (Trying out a local LLM after installing Ollama)
Local LLM, let’s go
Programming & CS Linux Survival Journal D-3 (PostgreSQL Installation)
I want to remotely access and control an unused laptop. Carrying both an unused laptop and the laptop I use is too heavy. To solve this, I’ll look into a real-time device called AnyDesk that allows access to another computer~
Programming & CS Playing Around with unittest
Let’s go, TDD
Programming & CS Linux Survival Log D-1 (Anaconda Installation)
I took another step toward creating a Python AI development environment. Very good.
Programming & CS Linux Survival Log D-2 (VS Code Installation)
\n🍳 VS Code Installation Tutorial\nFirst, you need to import Microsoft's GPG key and add the repository.\n\nThe package lists need to be updated.\n\nInstall Visual Studio Code~\n\n🍳 Thoughts\nInstalling VS Code itself is not particularly difficult. De
Programming & CS Linux Survival Log D-0 (Installing Ubuntu in WSL)
Cold Linux
Programming & CS Object lifecycle (whether the destructor is called depends on the object's lifetime)
When the destructor is called and when it is not (keyword: object lifecycle)
Founder Notes Selecting the Right OS
Ubuntu is the GOAT for machine learning:
Programming & CS Those Ambiguous Pointers
A collection of ambiguous ones
Founder Notes Design Process (feat. Retrospective on the KPMG Ideathon)
Agile~
Founder Notes Selecting Languages
I ended up writing a portfolio while trying to submit an assignment
Programming & CS When you're frustrated because you still don't understand it after searching for the algorithm, don't fucking use a library
If you don't understand the principles behind an algorithm or are told not to use a library, just copy and paste the library itself! ex) Finding all combinations, matching them, and comparing them
Programming & CS An Algorithm That Returns the Largest Element Among All Elements in a C++ vector
A useful algorithm – an algorithm that returns which element is the largest among all vector elements
Programming & CS Algorithm for deleting C++ vector elements without the algorithm library
A neat piece of code for deleting vector elements without using the algorithm library
Programming & CS Why the Heck Won’t Debugging Work!
I don’t know why this solves the problem, but this is the site I referred to. I think I still need to get more familiar with using VS Code. Ah, since I’m already using PyCharm, should I just use CLion too?
Programming & CS The GOAT Recursive Algorithm: Euclid’s Algorithm
The sheer brilliance that Thanos-snaps away 30 minutes of head-scratching.......
Programming & CS Setting up a Mac VS Code development environment
Development environments are always unfairly brutal.
Programming & CS What is a YAML file?
It's a rule for exchanging files between systems, and YAML files are really tasty.
Programming & CS An error that occurs when concatenating columns with the same names [InvalidIndexError: Reindexing only valid with uniquely valued Index objects]
When an error like this occurs, the problem is that data with the same columns was concatenated. Alternatively, the error may have occurred because data sets with mismatched numbers of items were concatenated. A nice explanation
Programming & CS What is config.py?
What is a configuration file?
Programming & CS What are .env environment variables?
Defining and using environment variables
Programming & CS Selectively Upload Files to GitHub
Create and use a .gitignore file.
Programming & CS A Legendary Explanation of How to Protect a Branch
\bLegendary Explanation
Programming & CS Legendary Explanation of Merge
Types of merge
Programming & CS A new application of list comprehension
A new application
Programming & CS Test code is damn important!
If you don't want to get smacked by Dr. Oh Eun-young, write your test code properly.
Programming & CS Why does null appear even though I used concat?
Use reset_index~
Programming & CS Easily combining pandas dataframes
Until then, I had only used the pd.concate method, but I discovered some mind-blowing code!
Programming & CS Why do I keep getting a key error when using apply?
Set the axis, y'all.
Programming & CS UUID
ㅠㅠID?
Programming & CS Wrong Abstraction
Moderation
Programming & CS What is a decorator (@)?
It literally means decorating a function; you can think of it as the concept of composite functions that we learned in mathematics. Decorators are used to implement additional functionality without modifying existing functions.
Programming & CS What Is Abstraction?
Definition: Grouping common attributes and methods together and giving them a name is called abstraction.
Data & ML RAGchain Benchmark: 3-Line Summary
Brief benchmark summary
Programming & CS Retrying Functions with Tenacity
Using a Dormammu-style loop to retry when an error occurs
Programming & CS Is there a function called by another function? (Callback Function)
Pikachu function, I choose you! Come out!
Programming & CS The Unspoken Rules of Naming
Naming contest
Data & ML What is context length?
It is the number of tokens an LLM can process at once. It is the maximum length of an input sequence for an LLM. A nice explanation. This is important because 1. A model cannot exceed the context length when summarizing articles. 2. Long-term planning ta
Programming & CS What Are Synchronous and Asynchronous?
Synchronous: Executing tasks one after another. → synchronous programming: developing programs so that multiple tasks are executed sequentially. Asynchronous: Executing tasks simultaneously rather than in sequence.
Programming & CS list comprehension in functional style
Another use of list comprehensions
Programming & CS When should you use static methods?
Static methods are mainly used when implementing utility methods.
Programming & CS Calling a static method from a method of the same class or a different class
Use the class name.method name format for a static method.
Programming & CS Hiding Methods or Property Names by Starting Them with _ to Make Them Private
Adding _ to a method or property prevents it from being called from outside (making it private).
Programming & CS How to Redefine an Inherited Method for Each Dataset = Method Override
Method override: adapting an inherited method to suit the characteristics of a child class~
Programming & CS Checking with a Boolean whether a specific value exists in a pandas DataFrame
Let's check whether a specific value exists in a pandas DataFrame using true or false.
Programming & CS Trying out the useful and thaaankful groupby, agg methods
Grouping by a specific column
Programming & CS How to merge row values based on duplicate values in a pandas DataFrame
Pandas is useful. To use useful tools, I guess you need to encounter situations where you have to deploy pandas in various situations. Thaaaank you, groupby method and agg method~
Data & ML What Are Qrels?
Do you know Dr. Query?
Programming & CS What is random_state?
Shuffle using pandas' sample method and fix the results when running it multiple times
Programming & CS How to Index DataFrames (loc, iloc, df[whatever])
Understanding pandas
Programming & CS Let's Learn About Python's sample
I used sample because sampling is more efficient than randomly shuffling the data frame in this situation.
Data & ML RAGchain benchmark Mr.tydi
Do you know Mr. TyDi?
Programming & CS Pandas: How to Drop Rows that Contain a Specific Value without drop() method and for loop?
Thanks a looooot, Pandas, for letting me avoid writing an algorithm—you little punk~ drop() the beat~
Data & ML MRR metric
What is MRR? (mean reciprocal rank)
Programming & CS Raising an Error with pytest.raise()
Answer me, Jarvis!!
Data & ML RAGchain Glossary
I’m organizing this place for my own reference because I keep coming across a barrage of unfamiliar words while reading papers.
Programming & CS When Returning Multiple Values in Functional Programming with the `apply` Function
What happens if the function passed as the `apply` parameter in functional programming returns multiple values? -> Create a zip and unpack it!
Programming & CS Creating multiple dataframes with apply
This is an article organizing the ideas I came to realize while thinking about how to write code that is Pythonic, readable, and efficient. I unpacked it with Zip.
Programming & CS Flattening
Misuse of list comprehension
Programming & CS apply function
You can make it more pandas-like by putting function logic inside the apply function.
Programming & CS Loading a File with the OS
I really don't understand what this code means. I need to put a relative path in file_path—what should I do? Nice explanation
Founder Notes How should I study to become a developer?
I don't know that sort of thing—I really don't know~
Programming & CS Why are some parameters fine with just a variable, while others require you to always include a value with `=`? (Positional argument vs. keyword argument)
Why are there parameters that require a value to be provided and parameters that don't?
Programming & CS Shallow Copy copy(), Deep Copy deepcopy()
Clone technique!
Programming & CS Dictionary.pop(Key)
pop
Programming & CS About the sorted() parameter key and lambda values
Lambor-lambda
Programming & CS What is yield? (feat. generators)
To yield
Programming & CS What is __init__.py?
Why isn't import working? / Why can't I call the class even though I created it? (TypeError: 'class' object is not callable)
Programming & CS What are : and ->?
Let's become a permanent commenter, not a temporary one
Programming & CS How to Use PyCharm with Mac
A MacBook is a Mac drum. This is a document meant to be used like an encyclopedia. Use command + F to find the feature you want~
Programming & CS Mastering Classes
Let's figure out this fucking object-oriented stuff
Programming & CS PyCharm error note (using fetch to pull changes from the GitHub website)
Conflict issue
Programming & CS DOM Concepts
What is the DOM?
Programming & CS Deploying a Goorm IDE Next.js Project to Vercel
A successful deployment forged through countless attempts and prayer over three months
Programming & CS When git add doesn't work even though the file is perfectly fine
Try deleting the .git file and pushing again
Programming & CS How to Merge
Fuuusion~~
Programming & CS About add/push-commit/pull-fetch
Organizing the concepts
Programming & CS goorm IDE GitHub Manual
On ending up back at square one because I didn't know how to use GitHub....
Programming & CS Information Processing Craftsman Wrong-Answer Notes
Muyaho
Programming & CS Error report: The following signatures could not be verified because the public key is not available in Goorm IDE
fucking error
Programming & CS Error report: Goorm IDE "The following signature is invalid" issue
Not an easy one
Programming & CS Git flow
Don't touch the main branch
Programming & CS Error report: Be Careful of Typos
As expected, the awesome folks at Stack Overflow!!
Programming & CS ErrorNote: error - TypeError: Cannot read properties of undefined (reading 'map') — Solution
The conclusion is that I’m a dummy~
Programming & CS Error note: "Could not find database with ID: 4f7c1e96-8935-4cbb-bcbb-d2d8d392145d. Make sure the relevant pages and databases are shared with your integration."
An error when using the Notion API in Postman
Programming & CS Error note: Invalid dom property ---. Did you mean ---?
Why className instead of class?
Programming & CS Error note: Invalid <Link> with <a> child. Please remove <a> or use <Link legacyBehavior\n
Tag <link> error
Programming & CS Error report: Expected corresponding JSX closing tag for <input>
An error that occurred while adding code to the footer file of Tailwind CSS's Tailblock
Programming & CS GitHub Terminology Guide
GitHub
Programming & CS Error report: Issue resolved—Tailwind CSS not being applied to Next.js on goorm IDE
5 days of trial and error
Programming & CS Goorm IDE GitHub Integration
Five days of trial and error
Programming & CS goorm IDE Next.js installation log
Next.js installation
Programming & CS Cloud IDE Expo Installation
Linux errors, go... go away! (Anyone who can't install Expo, come on, come on~)
Programming & CS What is Counter in collections?
Let's count the number of items in a dictionary
Programming & CS What is enumerate()?
Want to extract the indices and elements from a list all at once?
Programming & CS Regular Expressions: re
Let's analyze string patterns
Programming & CS Python Class Terminology Summary
class villain terms
Data & ML Blending
Delicious coffee blending—apparently the No. 1 algorithm in the Netflix prediction competition??
Data & ML Hyperparameter
https://rosypark.tistory.com/236
Data & ML PCA (Principal Component Analysis)
What is PCA?
Programming & CS Understandable IT Knowledge for Non-Majors
I don't know, I really don't know that kind of thing.
Data & ML Overfitting & Underfitting
What is overfitting?
Data & ML Supervised Learning (Classification)
Let's learn about classification
Data & ML Supervised Learning (Regression)
Let's learn about regression.
Data & ML Data preprocessing
Data preprocessing process
Data & ML Forms of Data
Participation in the Military AI/SW Competency Enhancement Program
Programming & CS The Zip Function, Variable Arguments (*/Variadic Arguments), and Keyword Arguments (**), Those Villainous Things
What on earth is *~~~~~
Programming & CS Calculating Time Complexity
Efficiency Issues
Founder Notes Why Is It Wrong?
Why Did It Fail?
Founder Notes Could Algorithms Also Be Considered Studying Mathematics?
A rant
Programming & CS Top-Down vs Bottom-Up
"As Planned"