<SCRIPT LANGUAGE="JavaScript">    
function enforceHanGul() {  
if(window.event.type == "propertychange" ){  
if ( window.event.propertyName == "value" ) {   
 var pattern = /[^(ㄱ-힣)]/g;   
 if(pattern.test(window.event.srcElement.value)){  
var v = window.event.srcElement.value.replace(pattern, "");  
window.event.srcElement.value = window.event.srcElement.value.replace(pattern, "");  
}  
}  
}  
}   
</SCRIPT>  
<input style="ime-mode:active" onfocus="this.style.imeMode='active'" onkeydown="this.focus()" onpropertychange='enforceHanGul()'>