style.css 파일에서는 아래 px 값들을 수정해주세요.

#kboard-ocean-gallery-list .kboard-list { float: left; width: 100%; text-align: center; }
#kboard-ocean-gallery-list .kboard-list img { display: inline; margin: 0; width: 220px; height: 155px; vertical-align: middle; border-radius: 3px; box-shadow: 0 1px 2px RGBA(0, 0, 0, 0.2); }
#kboard-ocean-gallery-list .kboard-list .kboard-gallery-item { display: inline-block; *display: inline; zoom: 1; padding: 0 10px; width: 220px; box-sizing: content-box; }
#kboard-ocean-gallery-list .kboard-list .kboard-no-image { line-height: 155px; }
#kboard-ocean-gallery-list .kboard-list .kboard-gallery-thumbnail { position: relative; float: left; width: 220px; text-align: center; }

그리고 list.php 파일에서는 아래의 수치를 동일하게 변경해주세요.

<!-- 리스트 시작 -->
<div class="kboard-list">
<?php while($content = $list->hasNext()):?>
    <div class="kboard-gallery-item">
        <div class="kboard-gallery-thumbnail">
            <?php
            if($content->thumbnail_file){
                $resize_img_src = kboard_resize($content->thumbnail_file, 220, 155);
            }
            else{
                $attach = current($content->attach);
                if($attach[0]){
                    $resize_img_src = kboard_resize($attach[0], 220, 155);
                }
                else{
                    $media = new KBContentMedia();
                    $media->content_uid = $content->uid;
                    $media->media_group = $content->uid;
                    $media_list = $media->getList();
                    $media_item = reset($media_list);
                    if(isset($media_item->file_path) && $media_item->file_path){
                        $resize_img_src = kboard_resize($media_item->file_path, 220, 155);
                    }
                    else{
                        $resize_img_src = '';
                    }
                }
            }
            ?>
            <?php if($resize_img_src):?>
            <img src="<?php echo $resize_img_src?>" style="max-width: 220px;" alt="">
            <?php else:?>
            <div class="kboard-no-image"><i class="icon-picture"></i></div>
            <?php endif?>
            <div class="kboard-gallery-foreground"><a href="<?php echo $url->set('uid', $content->uid)->set('mod', 'document')->toString()?>"><img src="<?php echo KBOARD_URL_PATH . '/skin/ocean-gallery/images/over-foreground.png'?>" style="max-width: 220px;" alt=""></a></div>
            <div class="kboard-gallery-username"><a href="<?php echo $url->set('uid', $content->uid)->set('mod', 'document')->toString()?>"><?php echo date("Y/m/d", strtotime($content->date))?> by. <?php echo $content->member_display?></a></div>
        </div>
        <div class="kboard-gallery-title cut_strings"><a href="<?php echo $url->set('uid', $content->uid)->set('mod', 'document')->toString()?>"><?php echo $content->title?></a></div>
    </div>
<?php endwhile?>
</div>
<!-- 리스트 끝 -->