Fix figures#67

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pismute merged 3 commits intoprogit:masterfrom

pismute:fix-figures

Dec 22, 2015

Commits on Dec 11, 2015

replace '디렉터리' with '디렉토리'
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Commits on Dec 20, 2015

fix figure2 and chapter 5.
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Commits on Dec 21, 2015

replace `→` with `&8594;`.
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