자동화 프로그램을 이용한 아동의 전체두개강내용적 평가

이정환,김지은,임성진,주가원,김시경,손정우,신철진,이상익,김혜리,Lee, Jeonghwan,Kim, Ji-Eun,Im, Sungjin,Ju, Gawon,Kim, Siekyeong,Son, Jung-Woo,Shin, Chul-Jin,Lee, Sang-Ick,Ghim, Hei-Rhee 대한생물정신의학회 2014 생물정신의학 Vol.21 No.3

Objectives Total intracranial volume (TIV) is a major nuisance of neuroimaging research for interindividual differences of brain structure and function. Authors intended to prove the reliability of the atlas scaling factor (ASF) method for TIV estimation in FreeSurfer by comparing it with the results of manual tracing as reference method. Methods The TIVs of 26 normal children and 26 children with attention-deficit hyperactivity disorder (ADHD) were obtained by using FreeSurfer reconstruction and manual tracing with T1-weighted images. Manual tracing performed in every 10th slice of MRI dataset from midline of sagittal plane by one researcher who was blinded from clinical data. Another reseacher performed manual tracing independently for randomly selected 20 dataset to verify interrater reliability. Results The interrater reliability was excellent (intraclass coefficient = 0.91, p < 7.1e-07). There were no significant differences of age and gender distribution between normal and ADHD groups. No significant differences were found between TIVs from ASF method and manual tracing. Strong correlation between TIVs from 2 different methods were shown (r = 0.90, p < 2.2e-16). Conclusions The ASF method for TIV estimation by using FreeSurfer showed good agreement with the reference method. We can use the TIV from ASF method for correction in analysis of structural and functional neuroimaging studies with not only elderly subjects but also children, even with ADHD.

군용 기동장비 내구 신뢰성 향상을 위한 동력장치 내구시험로 설계

이정환,이상호,조진우,강이석,Lee, Jeonghwan,Lee, Sangho,Cho, Jinwoo,Kang, Esok 한국군사과학기술학회 2017 한국군사과학기술학회지 Vol.20 No.3

The endurance test is important to evaluate and predict defects of the vehicles. In particular, in order to improve the reliability of the endurance test for the powertrain system of military vehicles, the driving load is measured and analyzed at test courses and maneuvering roads. As a result, new test courses for powertrain system is additionally needed to improve test reliability. In this paper, it shows that new test courses for powertrain system is designed and constructed using the measuring and anlayzing result between CPG test courses and army maneuvering roads.

3차원 노면굴곡 측정을 통한 운용지역 비포장 기동로의 가혹도 DB 구축

이정환,이상호,조진우,강이석,Lee, Jeonghwan,Lee, Sangho,Cho, Jinwoo,Kang, Esok 한국군사과학기술학회 2017 한국군사과학기술학회지 Vol.20 No.2

The profile of unpaved road is an important issue in the reliability of endurance test. Efforts on measuring 2D road profile and analyzing the severity have been continued in the study of performing reliable endurance test evaluations through reflecting the results of such measurement and analysis. However, 2D road profile has limitation in measuring the profile in the road width direction because data is obtained along the trailer wheel track. Therefore, in order to measure 3-dimensional shape of road surface and construct severity DB of 3D road profile, Changwon Proving Ground(CPG) of Agency for Defense Development(ADD) developed 3D profilometer which is composed of laser scanner, IMU, GPS, encoder and so on. This paper focuses on the analysis of unpaved road severity using 3D road profile for army operation roads. This results will be used to manage test courses severity of CPG.

안전관련 법제 강화에 따른 건설사업관리 분야의 입법정책적 과제 - CM/감리관련제도를 중심으로 -

이정환,정영철,Lee, Jeonghwan,Jung, Youngchul 한국건설관리학회 2022 한국건설관리학회 논문집 Vol.23 No.6

The death toll in the Korean construction industry accounts for more than 50% of all business deaths. This is the highest level among OECD countries, and the government has proposed various solutions to this, but has not seen any significant effect. In order to strengthen safety responsibilities and obligations to CEOs of companies in the blind spot of punishment, including those who have the greatest authority and influence in the construction industry, the Moon Jae In government strengthened various laws, including legislation of the Serious Accidents Punishment Act. However, at this point in time, half a year later, it is still questionable whether such punishment has been strengthened and the effectiveness of fragmentary measures has been exerted. This paper attempted to present legislative policy directions for the problems of the current system and future improvement measures to contribute to reducing significant accidents in the CM/supervision industry among the various subjects of the construction industry.

슈퍼픽셀의 밀집도 및 텍스처정보를 이용한 DBSCAN기반 칼라영상분할

이정환,Lee, Jeonghwan 디지털산업정보학회 2015 디지털산업정보학회논문지 Vol.11 No.4

In this paper, a method of color image segmentation based on DBSCAN(Density Based Spatial Clustering of Applications with Noise) using compactness of superpixels and texture information is presented. The DBSCAN algorithm can generate clusters in large data sets by looking at the local density of data samples, using only two input parameters which called minimum number of data and distance of neighborhood data. Superpixel algorithms group pixels into perceptually meaningful atomic regions, which can be used to replace the rigid structure of the pixel grid. Each superpixel is consist of pixels with similar features such as luminance, color, textures etc. Superpixels are more efficient than pixels in case of large scale image processing. In this paper, superpixels are generated by SLIC(simple linear iterative clustering) as known popular. Superpixel characteristics are described by compactness, uniformity, boundary precision and recall. The compactness is important features to depict superpixel characteristics. Each superpixel is represented by Lab color spaces, compactness and texture information. DBSCAN clustering method applied to these feature spaces to segment a color image. To evaluate the performance of the proposed method, computer simulation is carried out to several outdoor images. The experimental results show that the proposed algorithm can provide good segmentation results on various images.

수출용 무기체계 연동을 위한 EWR 모의기 설계

이정환(Jeonghwan Lee) 한국정보과학회 2023 한국정보과학회 학술발표논문집 Vol.2023 No.6

기업 보안 유형에 따른 보안사고 대응역량 : 사회기술시스템 이론 관점에서

이정환(Jeonghwan Lee),정병호(Byungho Jung),김병초(Byungcho Kim) 한국IT서비스학회 2013 한국IT서비스학회지 Vol.12 No.1

This study proceeded to examine the cause of the continuous secret information leakage in the firms. The purpose of this study is to find out what type of security among administrative, technological and physical security would have important influence on firm's security performance such as the security-incident response competence. We established the model that can empirically verify correlation between those three types of security and the security-incident response competence. In addition, We conducted another study to look at relation between developing department of security in the firms and reaction ability at the accidents. According to the study, the administrative security is more important about dealing with the security-incident response competence than the rest. Furthermore. a group with department of security has better the security-incident response competence and shows higher competence in fixing or rebui lding the damage. Therefore. this study demonstrates that investing in administrative security will be effective for the firm security.

개인화 스토리텔링 수학 학습 시스템

이정환 ( Jeonghwan Lee ),한기준 ( Keejun Han ),권가진 ( Gahgene Gweon ) 한국정보처리학회 2014 한국정보처리학회 학술대회논문집 Vol.21 No.1

개인화된 서술형 수학 문제(mathematics word problem)는 오랫동안 연구된 분야로 학생들의 학업 성취도와 수학에 대한 태도에 관심을 가져왔다. 본 연구에서는 2013년 도입된 스토리텔링 수학에 개인화된 콘텐츠를 접목하여 그 효과를 알아보고자 하였다. 초등학생 26명을 대상으로 하여 약 110분 동안 수업을 진행하였으며, 무게에 대한 새로운 개념을 배우는 데 그 목적을 두었다. 각각 13명씩 개인화 그룹과 비 개인화 그룹으로 나누어 수업을 진행하였다. 학업 성취도(Learning Achievement)에서는 사전 시험(pre-test) 점수가 너무 높아 두 그룹 간에 서로간의 유의한 차이점을 발견하지 못했다. 수학에 대한 태도 부분과 몰입도(Flow) 부분에서는 다소 개인화 그룹의 값이 높았지만, 통계적으로 유의한 정도는 차이는 아니었다. 하지만 정성적 분석에서는 차이가 있었다. 개인화 그룹(Personalized group)은 비 개인화 그룹(non-personalized group)에 비해 개인화(personalization)가 수업의 재미있는 요소로서 보다 중요한 작용을 했다고 느꼈다. 또한, 테스트나 측정(measure) 부분에서 생겼던 문제점을 개선하여 재 실험이 있을 시엔 유의미한 값을 나타낼 것으로 기대된다.

한국기업의 지배구조가 기업분할 유형선택에 미치는 영향에 관한 연구

이정환(Jeonghwan Lee),이진주(Jinju Lee),박남규(Namgyoo K. Park) 한국전략경영학회 2012 전략경영연구 Vol.15 No.1

본 연구는 한국기업을 중심으로 사업 포트폴리오를 재조정하고 경영효율을 극대화시키는 경영전략 방법 중 하나로 실행하는 기업분할시 유형선택에 대한 결정요인을 실증분석하였다. 2000년대부터 한국기업들의 기업분할 추세는 증가하였으며, 미국기업들과 달리 인적분할과 물적분할 두가지 형태를 취하였으나, 이에 대한 실증분석은 부족한 상황이다. 특히 대주주 중심의 가족소유 지배구조에서 많이 나타나는 물적분할 유형선택의 결정요인에 대한 분석은 거의 없다고 할 수 있다. 본 연구에서 기업 지배구조를 지배 대주주 지분비율, 비지배 대주주 존재여부, 대주주 또는 특수관계인 CEO 여부, 사외이사비율로 구분하여 기업분할 유형선택에 대한 결정요인을 로지스틱 회귀분석을 이용하여 분석하였다. 실증분석 결과 지배 대주주 지분비율이 높을수록 인적분할을 선호하는 경향이 있으며, 대주주 또는 특수관계인 CEO의 경우는 물적분할을 선호하는 경향이 나타났다. 비지배 대주주 존재여부와 사외이사비율은 기업분할 유형선택에는 영향을 미치지 못하는 것으로 나타났다. The purpose of this study is to investigate the relationship between corporate governance and the type of spin-off-a business portfolio restructuring strategy to improve management efficiency-choice in Korea. Spin-off in Korea typically takes the form of either equity or captive, which is different from the spin-offs observed in the United States. Although the number of spin-off cases in Korea has shown a steady increase since the 2000s, it has received less attention in the academia and is in need for a further in-depth investigation. In particular, very little research has been conducted on the investigation of the determinants of choosing the captive spin-off strategy under family ownership structures. Using the binary logistic regression, this research investigates the types of corporate governance structure and its relationship with the firm's choice of spin-off strategy by looking at the share proportion of the controlling shareholder, existence of an outside blockholder, appointment of a CEO who is the controlling shareholder or a family-related member of the controlling shareholder, and outside board representation. Our findings suggest that as the share of controlling shareholder increases, the tendency to prefer equity spin-off strategy increases whereas, when the CEO is the controlling shareholder or a family-related member of the controlling shareholder, the tendency to prefer captive spin-off strategy increases. However, we found no empirical evidence of the outside blockholder and outside board member's impact on the firm's decision to choose any type of spin-off strategy.

유동관내 가스하이드레이트 형성예측 및 제어

이정환(Jeonghwan Lee),백영순(Youngsoon Baek) 한국가스학회 2005 한국가스학회 학술대회논문집 Vol.2005 No.5