선천 상사근마비의 수직편위각에 따른 하사근 수술의 효과

허환,박상우,박영걸.Hwan Heo. M.D.. Sang Woo Park. M.D.. Yeoung Geol Park. M.D. 대한안과학회 2007 대한안과학회지 Vol.48 No.4

Purpose: To compare the postoperative results of inferior oblique muscle operation in congenital superior oblique palsy (CSOP) according to the preoperative vertical deviation. Methods: This study reviewed medical records of 26 patients who were diagnosed as CSOP with the largest vertical deviation at adducted position and incomitant vertical strabismus from May 2003 to April 2004 at hospital. The patients were divided into two groups, the group 1 (18 patients) shows less than 20 prism diopter (PD) vertical deviation at the primary position, the group 2 (10 patients) shows no less than 20 PD vertical deviation at the primary position preoperatively. We performed operation of the inferior oblique muscle (IOM) for both group. We evaluated the surgical effect at the primary position and both lateral gaze after 3 months. and performed reoperation as needed. Results: Mean correction amount of vertical deviation at primary position of two groups were 11.6±2.7 PD in the group 1 and 7.4±3.5 PD in the group 2. Postoperative vertical deviation was decreased compared to preoperative value and it was statistically significant. But there were statistically significant differences in the corrected amount after inferior oblique muscle operation between two groups at all gazes. Surgical result of group 1 was successful (100%), but in group 2, all failed (100%) and needed reoperation. Conclusions: This study showed that corrected amount with IOM operation was smaller in CSOP with no less than 20 PD vertical deviation at primary position and incomitant vertical strabismus. It may be taken into consideration when operation for rectus and oblique musle were performed simultaneously in CSOP.

일체형과 삼체형 아크릴 인공수정체의 장기 추적관찰 결과의 비교

허환,김황균,윤경철,박영걸,Hwan Heo,Hwang Gyun Kim,Kyung Chul Yoon,Yeoung-Geol Park 대한안과학회 2008 대한안과학회지 Vol.49 No.2

`Purpose: To compare the long-term clinical results of one-piece Acrysof? (SA60AT) hydrophobic acrylic intraocular lens (IOL) implantation compared with implantation of three-piece Acrysof? (MA60BM) hydrophobic acrylic IOL. Methods: We retrospectively analyzed each 50 eyes of 50 patients underwent MA60BM or SA60AT IOL implantation and followed for at least 6 months. Results: Final visual acuity of 0.5 or better was 38 eyes (76%) and 0.8 or better was 20 eyes (40%) in the SA60AT group. In the MA60BM group, it was 41 eyes (82%) and 23 eyes (46%) respectively. There were no significantly differences in predictability, intraocular pressure, endothelial cell density, astigmatism, and incidence of posterior capsule opacification between the two groups. Spherical equivalent at postoperative 1 week was -0.50±0.95D in SA60AT group and was -0.31±0.88D in MA60BM group (P=0.04). However, there was no significant difference between the two groups during follow up period. In MA60BM group, anterior chamber depth (P=0.02) and distance between iris and IOL (P=0.04) reduced significantly during the first postoperative month. Conclusions: Early postoperative axial displacement and changes in spherical equivalent can be occurred in MA60BM group. However there was no difference in long-term clinical results between SA60AT and MA60BM groups. `

안구건조증 환자에서 국소 테스토스테론 젤의 치료효과

허환,강인성,오미화,윤경철.Hwan Heo. M.D.. In Sung Kang. M.D.. Mei Hwa Wu. M.D.. Kyung Chul Yoon. M.D. 대한안과학회 2006 대한안과학회지 Vol.47 No.8

Purpose: To evaluate the therapeutic effect of topical testosterone gel application to periocular area in dry eye. Methods: Thirty-four eyes of 17 patients with refractory dry eye were included. Five patients had Sjogren`s syndrome and 12 were non-Sjogren`s syndrome patients. Testosterone gel was applied on the periocular area three times a day. Symptom score corneal sensitivity test (CST), tear film break-up time (BUT), basal tear secretion test (BST), fluorescein staining, tear clearance test (TCR), and conjunctival impression cytology were checked and evaluated before, one month after and two months after treatment. Results: The mean symptom score before topical testosterone gel application was 3.44±0.70; it was 2.88±0.84 at 1 month after application and 2.03±1.09 at 2 months after application. The improvement of tear film parameters including BUT, tear clearance rate, fluorescein staining score, conjunctival metaplasia and goblet cell density was statistically significant (P<0.05) at one and two months after treatment but neither BST nor CST was improved with statistically significance. There was no difference in the therapeutic effect of topical testosterone gel between Sjogren`s syndrome and non-Sjogren`s dry eye patients. Conclusions: The function of tear film and the integrity of ocular surface improved after topical application of testosterone gel in dry eye patients. Topical testosterone gel application may be an effective adjuvant therapy for the treatment of dry eye.

장애인을 위한 새로운 감성 인터페이스 연구

허환(Hwan Heo),이지우(Ji Woo Lee),이원오(Won Oh Lee),이의철(Eui Chul Lee),박강령(Kang Ryoung Park) 대한인간공학회 2011 大韓人間工學會誌 Vol.30 No.1

Objective: Making a new ergonomic interface system based on camera vision system, which helps the handicapped in home environment. Background: Enabling the handicapped to manipulate the consumer electronics by the proposed interface system. Method: A wearable device for capturing the eye image using a near-infrared(NIR) camera and illuminators is proposed for tracking eye gaze position(Heo et al., 2011). A frontal viewing camera is attached to the wearable device, which can recognize the consumer electronics to be controlled(Heo et al., 2011). And the amount of user's eye fatigue can be measured based on eye blink rate, and in case that the user's fatigue exceeds in the predetermined level, the proposed system can automatically change the mode of gaze based interface into that of manual selection. Results: The experimental results showed that the gaze estimation error of the proposed method was 1.98 degrees with the successful recognition of the object by the frontal viewing camera(Heo et al., 2011). Conclusion: We made a new ergonomic interface system based on gaze tracking and object recognition Application: The proposed system can be used for helping the handicapped in home environment

세계 패션디자인 교육 : 영국 Royal College of Art의 MA Fashion Design 과정

허환 ( Hwan Heo ) 한국의류학회 2011 패션정보와 기술 Vol.8 No.-

X-ray 영상에서 객체 기반의 노출 지수 측정 방법

허환(Hwan Heo),황영배(Youngbae Hwang) 제어로봇시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.9

The exposure index (EI) prevents systematic errors such as excessive or under-exposure by indicating the approximate value of the absorbed dose of the detector. We propose an EI measurement method with an object-based ROI except collimator and background region to measure more reliable EI values in X-ray images from digital flat-panel detectors. The boundary between the collimator and the background region has strong edges and linear components. Therefore, the ROI is detected by using simple and fast algorithms such as the canny edge detector, probabilistic Hough transform, and convex hull algorithm. The difference in the average pixel values between the ground truth (GT) values and the proposed method is approximately 5.13 (±1%).

차선 변화벡터와 카디널 스플라인을 이용한 곡선 차선 검출방법

허환 ( Hwan Heo ),한기태 ( Gi Tae Han ) 한국정보처리학회 2014 정보처리학회논문지. 소프트웨어 및 데이터 공학 Vol.3 No.7

본 논문에서는 카메라 파라미터가 필요 없는 역 투시변환 영상에 차선 변화벡터와 카디널 스플라인을 이용하여 변화에 강인한 곡선 차선 검출 방법을 제안한다. 이 방법은 역 투시변환과 차선 필터의 전처리 과정이 적용된 영상의 시작 S 프레임과 그 다음 S+1 프레임에서 차선 후보 영역을 설정하여 차선 영역을 검출하고, 검출된 차선영역을 이용하여 차선 변화벡터를 계산한 결과를 가지고 이후의 프레임에서 차선이 위치할 지점을 예측한다. 이후에 예측된 차선 위치에서부터 스캔 영역을 설정하고 이 영역 내에서 새로운 차선 위치를 검출하며, 검출된 차선 위치를 이용해 차선 변화벡터를 갱신하고, 차선 영역 내의 제어 점들에 카디널 스플라인을 적용하여 차선을 검출한다. 제안하는 방법은 차선의 형태 변화에 강인한 곡선 차선 검출방법이지만 직선 차선에도 잘 적응됨을 보였으며 한 프레임을 처리하는 데 약 20ms 정도의 양호한 차선검출 속도를 보였다. The detection method of curves for the lanes which is powerful for the variation by utilizing the lane variation vector and cardinal spline on the inverse perspective transformation screen images which do not required the camera parameters are suggested in this paper. This method detects the lane area by setting the expected lane area in the s frame and next s+1 frame where the inverse perspective transformation and entire process of the lane filter are adapted, and expects the points of lane location in the next frames with the lane variation vector calculation from the detected lane areas. The scan area is set from the nextly expected lane position and new lane positions are detected within these areas, and the lane variation vectors are renewed with the detected lane position and the lanes are detected with application of cardinal spline for the control points inside the lane areas. The suggested method is a powerful method for curved lane detection, but it was adopted to the linear lanes too. It showed an excellent lane detection speed of about 20ms in processing a frame.

'연관성 규칙ʼ 탐사를 이용한 상호운용성 정의의 해석

허환(Hwan Heo),김자희(Ja-Hee Kim) 한국전자거래학회 2011 한국전자거래학회지 Vol.16 No.2

'최근 정보기술? 이 발전함에 따라 전자거래가 증가되고, 시스템의 분산화가 빠르게 진행되면서 상호운용성의 중요성에 대한 공감대가 형성되고 있다. 그러나 적용분야와 이해관계자의 관점에 따라 상호운용성의 정의가 상이하여 특정 시스템에 요구되는 상호운용성의 수준이나 평가 방법에 관한 공감대는 여전히 부족한 실정이다. 예를 들어 국방 분야에서는 동일한 업무를 하는 관계 기관별로도 상이한 정의를 사용하며 상호운용성의 실질적인 시험평가는 정의와는 다소 무관하게 정보교환 능력 수준의 저차원적인 평가만을 수행한다. 본 연구에서는 다양한 상호운용성 정의를 수집하여 그 정의의 구성요소를 추출하고, 이들을 데이터 마이닝의 연관성 규칙 탐사 방법을 이용하여 새로운 상호운용성 정의를 제시한다. 이 정의를 기준으로 한국군에서 사용 중인 정의들과 비교 분석한다. 본 연구에서는 장바구니 분석기법을 이용하여 민간 및 국방 분야의 상호운용성 정의 구성요소의 연관성을 찾아, 가장 일반적이고 범용적인 정의를 도출하였다. 이 결과는 상호운용성에 대한 정의와 수준 및 평가항목 등에 대한 다양한 이해당사자들의 합의를 도출하는 데에 도움을 줄 것으로 기대한다. Lately, developing systems fully interoperable with others is considered an essential element for successful projects, as not only do e-commerce becomes ubiquitous but also distributed systems’ paradigm spreads. However, since definitions of interoperability vary by viewpoints, it is still difficult to have the same understanding and evaluation criteria on interoperability. For instance, various interoperability parties in military use different definitions of interoperability, and its T&E is not conducted according to the definition, but only to levels of information exchange. In this paper, we proposed a new definition of interoperability as follows. First of all, we collected existing and various interoperability definitions, extracting key components in each of them. Second, we statistically analyzed those components and applied the association rules discovery in data mining. We compared existing interoperability definitions to ours. From this research, we found associations among the components from various definitions applying market-basket analysis, redefining interoperability. Key findings of this research can contribute to a unified viewpoint on the definition, level, and evaluation items of interoperability.

역 투시변환과 차선 필터를 이용한 실시간 차선 검출방법

허환 ( Hwan Heo ),김성훈 ( Sung-hun Kim ),채일문 ( Il-moon Chae ),한기태 ( Ki-tea Han ) 한국정보처리학회 2012 한국정보처리학회 학술대회논문집 Vol.19 No.2

본 논문에서는 영상내 관심영역의 역 투시변환과 차선검출필터를 적용한 실시간 차선검출방법을 제안한다. 영상의 시작 프레임에서 소실점을 찾고 이를 기준으로 관심영역을 설정하고 차선을 예측하였으며, 예측된 차선을 기반으로 역 투시변환계수를 추출하여 원근감이 제거된 영상을 얻고, 이로부터 차선을 검출하였다. 제안한 방법은 원근감이 제거된 영상에 차선검출 필터를 적용하여 차선을 검출하는 방법으로, 처리영역을 축소하고 처리과정을 단순화 함으로써 초당 50 frames 정도의 양호한 차선검출 결과를 보였다.

X-ray 영상에서 객체 기반의 ROI 검출 방법

허환(Hwan Heo),황영배(Youngbae Hwang) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.6