Ob hom kev thwj cim yog dab tsi?
Cov txheej txheem thwj cim tau muab faib ua ob hom: kev sib cais thiab kev tsim cov txheej txheem:
1) txoj kev sib cais yog qhov uas cov khoom seem sib cais tawm ntawm qhov chaw seem ntawm ib txoj kab kev sib txuas lus thaum lub sijhawm thwj cim, thiab qhov zoo ntawm kev sib cais ntawm qhov chaw sib tw yuav tsum tau raws li qee qhov kev txwv.
2) txoj kev ua tus txheej txheem yog ua kom cov ntaub ntawv dawb pauv hauv yas deformation raws li qhov tsis muaj kev sib cais, thiab tig mus rau hauv cov khoom yam khoom, thiab ua tau raws li qhov yuav tsum tau ua kom qhov siab dav thiab ua rau.