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Material Event Report (Paid-in Capital Increase Decision) Correction Notice Seoul Electronic Communications Co., Ltd. Correction Date: September 17, 2026

1. Original Disclosure Document: Material Event Report (Paid-in Capital Increase Decision)

2. Original Submission Date: August 7, 2026

3. Correction Details

Item | Reason for Correction | Before Correction | After Correction 1. Type and Number of New Shares | Schedule change | Common Stock: 1,874,995 shares | Common Stock: 1,954,394 shares 4. Purpose of Fund Raising (Operating Funds) | | 899,992,000 won | 899,994,790 won 6. Issuance Price of New Shares | | 1,600 won | 1,535 won 7. Reference Stock Price | | 1,779 won | 1,706 won 9. Payment Date | | September 17, 2026 | October 2, 2026 12. Scheduled Listing Date of New Shares | | October 19, 2026 | November 2, 2026

20. Other Matters for Investment Consideration

Before Correction: 1) Subscription Details a. Subscription Date: September 11, 2026 b. Subscription Handler: Seoul Electronic Communications Co., Ltd. c. Subscription Deposit Management: KB Kookmin Bank Noryanggin Branch d. Stock Payment Date: September 17, 2026 e. Stock Payment Handler: KB Kookmin Bank Noryanggin Branch

2) Reference Stock Price Calculation Table (Unit: shares, won) Date | Trading Volume | Trading Value | Remarks September 4, 2026 | 106,485 | 188,910,394 | 5th trading day prior to subscription date September 7, 2026 | 31,292 | 56,372,664 | 4th trading day prior to subscription date September 8, 2026 | 45,781 | 81,198,583 | 3rd trading day prior to subscription date Total | 183,558 | 326,481,641 | - Reference Stock Price (Weighted Arithmetic Average): 1,778.63 won Discount or Premium Rate (%): -10 Issuance Price: 1,600 won

3) Selection process, transaction details, and allocation details by third-party allocation recipient Ha Tae-hyung | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 624,999 | - Park Gil-sang | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 499,999 | - Park Jin-nam | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 124,999 | - Park Jin-seok | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 312,499 | - Lee Hyun-jeong | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 312,499 | -

4) In case the Material Event Report is corrected five or more times as a third-party allocation - Reason for Correction: Change in fund use purpose and subscription date - Future Plan: The company will make every effort to proceed according to schedule through close consultation with allocation recipients.

After Correction: 1) Method of calculating issuance price of new shares 2) Subscription Details a. Subscription Date: September 22, 2026 b. Subscription Handler: Seoul Electronic Communications Co., Ltd. c. Subscription Deposit Management: KB Kookmin Bank Noryanggin Branch d. Stock Payment Date: October 2, 2026 e. Stock Payment Handler: KB Kookmin Bank Noryanggin Branch

3) Selection process, transaction details, and allocation details by third-party allocation recipient

Third-Party Allocation Recipient | Relationship with Company or Major Shareholder | Selection Process | Transaction Details and Plans within 6 Months Before and After Capital Increase Decision | Allocated Shares (shares) | Remarks Ha Tae-hyung | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 651,465 | - Park Gil-sang | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 521,172 | - Park Jin-nam | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 130,293 | - Park Jin-seok | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 325,732 | - Lee Hyun-jeong | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 325,732 | -

4) In case the Material Event Report is corrected five or more times as a third-party allocation - Reason for Correction: Correction at request of subscriber - Future Plan: The company will make every effort to proceed according to schedule through close consultation with allocation recipients.

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MATERIAL EVENT REPORT To: Financial Services Commission Date: September 17, 2026

Company Name: Seoul Electronic Communications Co., Ltd. Representative Director: Lee Jae-hyun Head Office Address: 4 Saebul-ro, Bupyeong-gu, Incheon Telephone: 032-723-4111 Website: http://www.seoulset.co.kr Prepared by: Park Byung-moo, Reporting Affairs Officer, 032-723-4111

PAID-IN CAPITAL INCREASE DECISION

1. Type and Number of New Shares Common Stock: 1,954,394 shares Other Stock: - shares

2. Par Value per Share: 500 won

3. Total Issued Shares Before Capital Increase Common Stock: 13,917,769 shares Other Stock: - shares

4. Purpose of Fund Raising Facility Funds: - won Business Transfer Funds: - won Operating Funds: 899,994,790 won Debt Repayment Funds: 600,000,000 won Securities Acquisition Funds of Other Companies: 1,500,000,000 won Other Funds: - won

5. Method of Capital Increase: Third-Party Allocation

6. Issuance Price of New Shares Common Stock: 1,535 won Other Stock: - won

7. Reference Stock Price Common Stock: 1,706 won Other Stock: - won

7-1. Method of Calculating Reference Stock Price: Weighted arithmetic average stock price for the 3rd to 5th trading days prior to subscription date

7-2. Discount or Premium Rate (%): -10

7-3. Basis for Discount (Premium) Rate: In accordance with Article 5-18 (Determination of Issuance Price for Paid-in Capital Increase) of the Regulations on Issuance and Disclosure of Securities, the issuance price is determined by applying a 10% discount rate to the weighted arithmetic average stock price from the 3rd to 5th trading days prior to the subscription date as the reference stock price. (Amounts less than one won are truncated.)

8. Basis in Articles of Incorporation for Third-Party Allocation: Article 10, Paragraph 2 of the Company's Articles of Incorporation

9. Payment Date: October 2, 2026

10. Dividend Base Date of New Shares: January 1, 2026

11. Scheduled Date of Stock Certificate Delivery: -

12. Scheduled Listing Date of New Shares: November 2, 2026

13. Circumvention of Listing through In-Kind Contribution: No - Whether in-kind contribution exists: No - Whether unlisted company shares exist among in-kind contribution assets: Not applicable - In-kind contribution value of shares to be paid: - won - Ratio to total assets of company's most recent fiscal year: - % - Number of shares to be paid: -

14. Fulfillment of Circumvention of Listing Requirements: Not applicable

15. Board Resolution Date (Decision Date): August 7, 2026 - Independent (Outside) Director Attendance: Present (1), Absent (-) - Auditor (Audit Committee) Attendance: Present

16. Whether Subject to Securities Registration Statement Submission: No

17. Reason for Exemption from Submission: Submission of small-amount public offering disclosure documents

18. Whether Applicable to Short-Selling Transaction Period in Which Subscription is Prohibited: No - Start Date: - - End Date: -

19. Whether Subject to Fair Trade Commission Reporting: Not applicable

20. Other Matters for Investment Consideration

1) This paid-in capital increase is a small-amount public offering method implemented under Article 130 (Recruitment and Sale without Submission of Registration Statement) of the Capital Markets and Financial Investment Business Act, as the public offering amount is less than 3 billion won and no securities registration statement is submitted.

2) Subscription Details a. Subscription Date: September 22, 2026 b. Subscription Handler: Seoul Electronic Communications Co., Ltd. c. Subscription Deposit Management: KB Kookmin Bank Noryanggin Branch d. Stock Payment Date: October 2, 2026 e. Stock Payment Handler: KB Kookmin Bank Noryanggin Branch

3) Other Precautions a. Subscription deposits shall be replaced with stock payment on the payment date, and no interest shall be paid from the subscription date to the payment date. b. If the number of subscribed shares falls short of allocated shares and unexercised shares occur, the remaining shares shall be treated as unissued. c. The above schedule may be changed depending on consultations with relevant authorities and other circumstances. All details regarding the issuance of new shares are delegated to the Representative Director. d. Regarding this third-party allocation paid-in capital increase, the notice of new share issuance plan pursuant to Article 418, Paragraph 4 of the Commercial Act shall be replaced by submitting the Material Event Report to the Financial Services Commission and Korea Exchange one week prior to the stock payment date in accordance with Article 165-9 of the Capital Markets and Financial Investment Business Act.

Reference Stock Price Calculation Table (Unit: shares, won)

Date | Trading Volume | Trading Value | Remarks September 15, 2026 | 25,224 | 43,253,587 | 5th trading day prior to subscription date September 16, 2026 | 59,812 | 101,551,518 | 4th trading day prior to subscription date September 17, 2026 | 14,923 | 25,698,873 | 3rd trading day prior to subscription date Total | 99,959 | 170,503,978 | - Reference Stock Price (Weighted Arithmetic Average) | | 1,705.74 | Discount or Premium Rate (%) | | -10 | Issuance Price | | 1,535 |

Basis for Third-Party Allocation, Purpose, etc.

Articles of Incorporation Provision Serving as Basis for Third-Party Allocation: Article 10 (Right to Subscribe for New Shares) ① Shareholders have the right to be allocated new shares in proportion to the number of shares they own. ② Notwithstanding the provision of Paragraph 1, the company may, by board resolution, allocate new shares to persons other than shareholders in any of the following cases: 1. When issuing new shares by general public offering method within a range not exceeding 50% of total issued shares in accordance with Article 165-6 of the Capital Markets and Financial Investment Business Act 2. When issuing new shares due to exercise of stock purchase options under Article 542-3 of the Commercial Act 3. When issuing new shares due to exercise of employee stock purchase options within a range of 20% of total issued shares 4. When issuing new shares due to exercise of employee stock purchase options under Article 39 of the Framework Act on the Welfare of Workers 5. (Deleted March 30, 2026) 6. When issuing new shares to specific persons (including company shareholders) such as domestic and foreign financial institutions and institutional investors, domestic and foreign corporations or individuals, etc., to achieve important business objectives such as important technology introduction, research and development, production, sales, capital alliance, urgent fund raising, improvement of financial structure, and other business purposes ③ When issuing new shares pursuant to any of the provisions in Paragraph 2, the type, number, and issuance price of shares to be issued shall be determined by board resolution. ④ The handling method for shares resulting from waiver or loss of subscription rights for new shares and fractional shares resulting from new share allocation shall be determined by board resolution.

Purpose of Third-Party Allocation Capital Increase: Securing operating funds

Specific Use Purpose of Funds Raised through Third-Party Allocation

Operating Funds (Unit: million won) Fund Use | Details | Planned Use by Year | Total | | 2026 | 2027 | After 2027 | Operating Funds | Personnel expenses, material costs, investment | 899 | - | - | 899

Debt Repayment Funds (Unit: million won, %) Category | Borrowing Source | Borrowed Amount | Borrowing Date | Maturity Date | Interest Rate Short-term Borrowing | S2B Network Co., Ltd. | 600 | March 21, 2026 | - | 4.31

(*) The company plans to repay immediately upon completion of this small-amount public offering paid-in capital increase.

Securities Acquisition Funds of Other Companies / Business Transfer Funds Fund Use | Transaction Counterparty | Securities Issuing Company | Business Description of Securities Issuing Company (Main Content of Business Transfer) | Basis for Acquisition Price Calculation Securities Acquisition Funds of Other Companies | To be determined | To be determined | To be determined | To be determined

Note 1) This is planned to be used as securities acquisition funds of other companies, and a corrective disclosure will be made upon confirmation.

Third-Party Allocation Recipients, Selection Process, Transaction Details, and Allocation Details

Third-Party Allocation Recipient | Relationship with Company or Major Shareholder | Selection Process | Transaction Details and Plans within 6 Months Before and After Capital Increase Decision | Allocated Shares (shares) | Remarks Ha Tae-hyung | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 651,465 | - Park Gil-sang | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 521,172 | - Park Jin-nam | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 130,293 | - Park Jin-seok | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 325,732 | - Lee Hyun-jeong | - | Selected considering achievement of company's business objectives, prompt fund raising, timing, and future business direction | - | 325,732 | -

In Case the Material Event Report is Corrected Five or More Times as a Third-Party Allocation Reason for Correction: Correction at request of subscriber Future Plan: The company will make every effort to proceed according to schedule through close consultation with allocation recipients.