Palgwae

This appears to be a tile of some sort, that was used on the palace grounds, of a palace in Seoul. I immediately recognised it to be a depiction of palgwae (Chinese: Baqua), although a strange depiction at that. Palgwae are the eight trigrams that surround the taegeuk. The taegeuk is known in Chinese as the Taijitu, or better known in the West as the yin-yang symbol. Trigrams are symbols; basically three horizontal bars -- some of the bars are broken and some are unbroken. Each trigram have a special meaning based on the I-Ching, the Chinese "Book of Changes".

On this tile the taegeuk, which should be in the middle and surrounded by the palgwae (eight trigrams) is missing. The image below shows the trigrams with their Chinese names, surrounding the taegeuk in the middle.

In the tile, the taegeuk is replaced with the Gam trigram [ ☵ ] (an unbroken line sandwiched by two broken lines). The Gam [ 감 ] trigram symbolises the water-element and its familial relationship is "middle son". As it symbolises water, it would be the representative trigram for my personal Taekwon-Do group in South Africa, known as the Soo Shim Kwan. "Soo" means water and "Shim" means mind and is therefore the idea of "being like water".

I'm curious as to why this tile does not have the taegeuk in the middle, but instead the Gam trigram, and what symbolic value this serves.