Mr. SUPORNCHAI SIRIWOHARN Mr. Supornchai Siriwoharn, the chief executive officer of the International Engineering Public Company Limited (“IEC”), a person responsible for the operation of IEC to

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sales and services to sales ratio for the Group were 71.96% in 2017 compared to 79.17% in 2016. The decrease in the cost of sales ratio is due to the effectiveness of controlling and managing the budget

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