간단한 로직이지만 꼭 필요한 분들이 계실것 같아서
어느님 질답란에 올러온 답변을 여기에 올립니다.


<script type="text/javascript">
function onoff(obj){ //셀렉트 조건에따라 input문 on off함수
tg1 = document.getElementById('mb_9');
if(obj=='일반'){
tg1.value='';
tg1.disabled=true;
tg1.style.background="#eeeeee";
}else{
tg1.disabled=false;
tg1.style.background="#ffffff";
tg1.focus();
}
}

function NumOn(){
if (event.keyCode >= 48 && event.keyCode <= 57) { //숫자키만 입력 받는 함수
return true;
} else {
alert("숫자만 입력할 수 있다.");
event.returnValue = false;
}
}
</script>




<tr>
<td height="30"><img src="<?=$member_skin_path?>/img/분류.gif" /></td>
<td>
<select id=mb_8 name=mb_8 itemname='분류' required onchange="onoff(this.options[this.selectedIndex].value);">
<option value='해사' <? if($mb_8=='해사') echo 'selected'; ?>>해사</option>
<option value='해간' <? if($mb_8=='해간') echo 'selected'; ?>>해간</option>
<option value='ROTC' <? if($mb_8=='ROTC') echo 'selected'; ?>>ROTC</option>
<option value='부사관' <? if($mb_8=='부사관') echo 'selected'; ?>>부사관</option>
<option value='병' <? if($mb_8=='병') echo 'selected'; ?>>병</option>
<option value='일반' <? if($mb_8=='일반') echo 'selected'; ?>>일반</option>
</select>&nbsp;&nbsp;
<input id=mb_9 name=mb_9 size=5 itemname="기수" value="<?=$member[mb_9]?>" <?=$member[mb_9]?" class=ed2":"class=ed";?> style="ime-mode:disabled;" onKeyPress="NumOn(this);">*숫자만 입력
</td>
</tr>
<tr>
<td height="1" colspan="2" bgcolor="#cdcdcd"></td>
</tr>