00000nz  a2200000n  4500
001  KSH1998028680
005  19991230133428
008  980429 n azknn|abn          |a a|a    | 
150  ▼a동토[凍土]▲
550  ▼wg▼a토양[土壤]▲
550  ▼wh▼a영구 동토대[永久凍土帶]▲
550  ▼a동결 침투[凍結浸透]▲
550  ▼a동토층[凍土層]▲