Katakana Analysis final

Two typical examples of kanakana usage

(1)  Onomatopoeia

Dog——ワンワン     Cat――ニヤーニヤー       Frog――ケロケロ

Pig――ブーブー     Bird――ピッピッピッ      Duck――ガーガー

Bee――ブーンブーン

(2) Loan Words

カレーライス、 スポツ、ダンス、レストラン、バス

The following are some special katakana usage examples I find.
1. Though loan words from ancient Chinese are usually written in kanji. For loanwords from modern Chinese, katakana is used.

Japanese	Rōmaji	Meaning	Kanji	Romanization	Source language
マージャン	mājan	mahjong	麻將	májiàng	Mandarin
ウーロン茶	ūroncha	Oolong tea	烏龍茶	wūlóngchá
チャーハン	chāhan	fried rice	炒飯	chǎofàn
チャーシュー	chāshū	barbecued pork	叉焼	cha siu	Cantonese
シューマイ	shūmai	a form of dim sum	焼売	siu maai

I think the reason why this is the case is that the modern Chinese words cannot be well or correctly understood by Japanese people. The kanji Japanese people are using almost keeping their original meaning in ancient Chinese, while we Chinese add a lot of new meanings to Chinese characters. Even though some words are written in the same way, we have different understanding with Japanese. A simple example, "勉强" as kanji in Japanese it means study, however in Chinese it means “force somebody to do something he'/she does not want to do”; Totally different meanings! Given there is no advantage of understanding for use kanji in these loanwords, I think katakana is more convenient for reading. ^^ 

2. Katakana is also used for emphasis, especially on signs, advertisements, and hoardings. For example, it is common to see ココ ("here"), ゴミ ("trash"), or メガネ ("glasses").
Words the writer wishes to emphasize in a sentence are also sometimes written in katakana, mirroring the European usage of italics.

Actually I fail to fully understand when katakana words can be used for emphasis for Japanese people. Like posted メガネ  on glasses to remind people do not run into it. I think a big word written in red or other shining colors is striking enough to attract people's attention.
However, I can understand if it is in a long paragraph, katakana words are special compared with other words. Just like same capital words in Japanese. BTW, there is no similar situation in Chinese, though there are simplified Chinese and traditional Chinese, I do not think transforming from these two kinds of Chinese has such function.

3. ヒフ科("dermatology"). 
Some difficult-to-read kanji are written with katakana. For this example, the kanji is "皮膚科". The second kanji is rather complicated and difficult to read. Thus this word is commonly written as 皮フ科 or ヒフ科, mixing kanji and katakana.

I think the reason why katakana has such function is that katakana is a kind of phonetic symbol. For people who know all the katakana, they can read it, and then get the meaning. However, kanji does not have that characteristic. That’s why Chinese is so difficult even for Chinese people.