David (Joonseok) Lee

David (Joonseok) Lee

Business Development Manager

Always curious and eager to learn, I enjoy turning ideas into sustainable business opportunities.I'm passionate about building new things, exploring new industries, and connecting people, products, and markets.

About

I am a Business Development Manager based in Cheonan, South Korea. I helped generate over USD 5 million in gross revenue by securing and managing a manufacturing partnership for beauty device production. I am constantly learning new things to expand my understanding of how industries, technologies, and products work — including drone AI, game development, e-commerce, and manufacturing.

Currently, I'm a Business Development Manager at ID SYSTEM, where I build relationships with manufacturing partners and develop new business opportunities. I'm passionate about creating new value within the company and being part of something bigger than just myself. I manage sales channels with COWAY and ECODMLAB, oversee manufacturing-related projects, and help create new revenue streams. My current focus is on expanding beyond existing business channels and identifying new opportunities for long-term growth.

In the past, I've had the opportunity to work across a variety of settings — from hummingavis and the Republic of Korea Army to Akshon Esports and Venture Port. I also have extensive esports experience with organizations like Red Flag Esports, Crew Esports, Team Turquality, and GosuGamers.

When I'm not working, I'm usually coding in C#, playing basketball, making music with FL Studio, cleaning, doing volunteer work, or learning new skills.

My Journey

The experiences and moments that shaped who I am today. Every chapter has contributed to my perspective and passion for what I do.

David performing in a school musical in Hungary
1995 - 2008Turkey & Hungary

Early Childhood — Where It All Began

I was born in Istanbul into a family of five children. Growing up, I spoke Turkish in daily life, learned in English at school, and communicated in Korean at home. From 2006 to 2008, I lived in Budapest, Hungary, which remains one of the most meaningful periods of my life.

Played lead roles in two musicals as a middle school student in HungaryLearned to love and play basketball while living in Turkey and HungaryParticipated in various volunteer activities, including gypsy ministry work in Hungary
David coaching at the Turkish League of Legends Championship
2014 - 2016South Korea & Turkey

Esports Journey — League of Legends Phase

I began my professional esports journey as a journalist. My love for League of Legends grew as I organized collegiate events across Korea, interviewed international players, and became more involved in the competitive scene. I later became the head coach of three professional teams in Turkey, becoming the first Korean coach in the Turkish League of Legends scene.

Organized collegiate esports events at Incheon Global Campus and in PohangBecame the first Korean coach in the Turkish League of Legends sceneHelped bring Korean players into the Turkish scene, including serving as Griffin Sword's first coach
David and teammates at the International Humanitarian Law Moot Court Competition
2017 - 2021Handong Global University, Pohang

College Grind

After working in esports, I enrolled in a U.S. & International Law program while double majoring in Counseling Psychology. During university, I worked through internships, teaching assistant roles, and a remote role at Akshon Esports, where I helped John Kim develop his esports identity in the Overwatch scene. I gained exposure to startups, the legal industry, and professional communication.

Graduated with a 3.58/4.5 GPA in U.S. & International Law and Counseling PsychologyInterned at Venture Port, working with various startup CEOsWon "Best Mooter" and "Best Defendant" at the International Humanitarian Law Moot Court Competition hosted by the Korean Red Cross
A touching moment during volunteer work with Global Overseas Adoptees' Link
120+ HoursVarious Organizations

Giving Back — Volunteer Work

When I was younger, I was often inspired by stories of capable people helping those in need. That inspiration led me to seek out community service opportunities. Over time, my perspective matured. I no longer see volunteering as one person helping another from a position of superiority. Instead, I believe all people, regardless of background, share the same dignity and needs. Helping our neighbors is part of building a healthier and more connected community.

Helped Tammy reconnect with her rescuer before she was adopted (Global Overseas Adoptees' Link)Assisted children with learning disabilities at Doongji Community Disabled Child CenterShared music with children at an orphanage in Paju

Experience

2024 — Present

Business Development Manager · ID SYSTEM

  • Joined the Sales and Business Development Team in May 2024 as an Assistant Manager.
  • Discovered ECODMLAB in July 2024 and initiated the first meeting for beauty device OEM production.
  • Drafted the production contract in September 2024 and contributed approximately KRW 1.5 billion / USD 1 million in revenue for 2024.
  • Took charge of new products from the PP stage to mass production, including production management and customer management.
  • Managed production projects: V1 (Quadthera Original), M1 (Minitune), T1 (Titan), PS1 (Pearl Shot), F1 (Pre-launch).
  • Promoted to Manager in November 2025 after being recognized as an outstanding employee.
  • Supported overall revenue growth from KRW 6.8B (2023) to projected KRW 20B (2026).
Business DevelopmentNegotiationNetworkingManufacturingProject ManagementClient ManagementProduction Management
2023 — 2024

Business Development Junior Manager · hummingavis

  • Developed the company's Amazon Seller Account for B2C K-beauty products.
  • Finalized a marketing contract with Therabox and led a campaign through its U.S. subscription program.
  • Finalized B2B sales contracts with Ecoren International (Taiwan), YesAsia, and White Edge (Malaysia/Guardian).
  • Improved the Amazon Seller Account to 3.0+ ROAS, with performance reaching an average ROAS of 6.5 at its peak.
  • Led PPC advertising campaigns for K-beauty hair care products.
  • Helped lead the hero product into the top 20 best-selling products in its Amazon U.S. hair care category.
Business DevelopmentE-commerceAmazon Seller CentralPPC MarketingExcelB2B SalesMarketingK-beauty

Contact

Get In Touch

I'm open to new opportunities, collaborations, and conversations.I'm especially interested in roles and projects that combine business development, technology, and games. Feel free to reach out!

Say Hello