자동차 공조 시스템의 발전 동향

이대웅,안용귀,박창호,Lee Dae-Ung,An Yong-Gwi,Park Chang-Ho 대한설비공학회 2006 설비저널 Vol.35 No.10

당뇨망막병증 검진에 있어 무산동 디지털 안저사진기의 효용성

이대웅,배정훈,송수정.Dae Woong Lee. MD. Jeong Hoon Bae. MD. Su Jeong Song. MD 대한안과학회 2011 대한안과학회지 Vol.52 No.5

Purpose: To evaluate the efficacy of a single field, non-mydriatic, 45° digital photography as a diagnostic tool for diabetic retinopathy. Methods: A total of 303 consecutive diabetic patients (606 eyes) who underwent digital fundus photography and indirect ophthalmoscopy were included in the present study. The optical discs and macular area of all patients were subjected to single fundus photography using a non-mydriatic 45-degree digital fundus camera. All patients also underwent fundus examinations after pupil dilation via indirect ophthalmoscopy. Results: The sensitivity and specificity for determining diabetic retinopathy were 47.6% and 97.6%, respectively. The false positive rate, false negative rate, positive predictive value, and negative predictive values were 2.3%, 2.1%, 45.5%, and 97.8%, respectively. Among the digital fundus images, 12.9% (78 eyes) were non-gradable. The patients with non-gradable digital fundus images were older (p < 0.001), had a longer duration of diabetes, (p < 0.001) and more often suffered from systemic hypertension (p = 0.003) compared to patients with gradable photographs. Conclusions: The present study showed that single-field, non-mydriatic, 45 degree digital photography for detecting diabetic retinopathy had relatively low sensitivity and high technical failure rates. The failure rates could be improved with higher resolution non-mydriatic wide-field photography cameras and with additional peripheral images for diabetic retinopathy screening. J Korean Ophthalmol Soc 2011;52(5):531-536

제2형 당뇨병 환자에서 당뇨망막병증에 대한 지식 및 인지도조사: 서울시 당뇨병예방사업 설문 조사결과

이대웅,박철영,송수정,Dae Woong Lee,Chul Young Park,Su Jeong Song 대한안과학회 2011 대한안과학회지 Vol.52 No.11

Purpose: To investigate the knowledge and awareness level of diabetic retinopathy (DR) in type 2 diabetes patients. Methods: A total of 437 participants with diabetes were recruited in the Seoul Metro-City Diabetes Prevention Program (SMC-DPP). Participants underwent clinical and laboratory examinations and questionnaire survey to evaluate diabetes complications. The DR was diagnosed by grading fundus photographs 5 standard fields taken per eye. Results: The overall prevalence of any DR was 20.4% and only 6.6% of patients were aware of their DR. The DR patients who underwent an eye examination within the previous year were 42.3%, and 50.3% out of 437 patients enrolled were educated on diabetes. Of the survey participants, 83.8% answered positive to ‘Evaluation of diabetes mellitus complication must be performed every year’, 61.1% answered positive to ‘Must control blood pressure and lipid level for diabetes management’ and 28.4% believed ‘It takes a long time for complications of diabetes to develop’. The DR self awareness was 14.6% and an eye examination within the previous year was 50.6% among the 89 DR participants. Conclusions: Results of the survey with SMC-DPP type 2 diabetes participants showed a low knowledge and awareness level of chronic complications such as DR. J Korean Ophthalmol Soc 2011;52(11):1296-1301

자동차 공기청정시스템 기술동향

이대웅,Lee, Dae-Ung 한국공기청정협회 2008 空氣淸淨技術 Vol.21 No.2

고분자전해질 연료전지 고분자막의 특성 및 성능 비교

이대웅,오소형,임대현,정회범,유승을,구영모,박권필,Lee, Daewoong,Lim, Daehyun,Oh, Sohyeong,Chung, Hoi-Bum,Yoo, Seung-Eul,Ku, Young-Mo,Park, Kwonpil 한국화학공학회 2020 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.58 No.2

In the proton exchange membrane fuel cells (PEMFC), the development of a reinforced membrane with improved durability by a support is actively in progress in Korea. In this study, the initial performance and characteristics of four types of reinforced membranes were compared. Reinforced membranes with higher amounts of C-F chains in the polymer membrane showed lower water diffusion coefficients due to the hydrophobicity of the C-F chains. The thicker the polymer membrane, the more the hydrogen permeability decreased and the higher the OCV. Membrane with short resistance below 1.5 Ωcm² showed OCV below 0.9 V and the lowest performance, so short resistance should be above 3.0 Ωcm². Compared with the current standard membrane, there was a similar domestic membrane, which could confirm the possibility of localization of PEMFC polymer membrane. 고분자전해질 연료전지(PEMFC)에서 지지체에 의해 내구성을 향상시킨 강화막(Reinforced Membrane)의 개발이 국내에서 활발히 진행되고 있다. 본 연구에서는 4 종류의 강화막의 초기 성능 및 특성을 비교하였다. 고분자막의 C-F사슬의 양이 더 많은 강화막이 C-F사슬의 소수성 때문에 물 확산계수가 더 작음을 보였다. 고분자막 두께가 두꺼울수록 수소투과도가 감소하고 OCV가 증가함을 확인하였다. Short 저항이 1.5 Ωcm² 이하인 막은 OCV가 0.9 V이하이고 성능도 최저여서 Short 저항이 3.0 Ωcm² 이상이어야 함을 보였다. 현재 기준이 되는 국외 막과 비교했을 때 비슷한 국내 막도 있어서 PEMFC 고분자막의 국산화 가능성을 확인할 수 있었다.

데이터마이닝 분석방법을 활용한 고령자의 자살위험 예측요인 분석

이대웅 ( Dae Woong Lee ),문상호 ( Sang Ho Moon ),이효주 ( Hyo Joo Lee ),이소담 ( So Dam Lee ) 한국정책학회 2016 韓國政策學會報 Vol.25 No.1

본 연구에서는 데이터마이닝 분석방법을 활용하여 고령자의 자살위험 예측요인에 대한 분석을 실시하였다. 특히, 의사결정나무모형과 로짓모형, 신경망분석을 활용하여 고령자 자살위험 예측을 위한 요인을 도출하고 요인 간의 상호작용(interaction) 패턴에 대한분석을 시도하였다. 이를 통해 개개인 가지고 있는 다양한 상황과 특성들에 적합한 개별적 개입 방안을 마련하는 근거를 제시하고자 하였다. 분석결과를 요약하면 다음과 같다. 의사결정나무 모형 결과, 고령자의 자살경험에 가장 큰 영향을 미치는 변수는 우울증 정도이며, 다음으로 중요한 예측변수는 주거환경 만족도로 도출되었다. 또한 우울증을 앓고 있으며, 주거환경 만족도가 낮은 고령자가 여가생활에 불만족할 경우 자살 위험이 증가하는 것으로 나타났다. 나아가 가장 자살위험이 높은 집단은 우울증세를 앓고 있으며, 주거환경과 여가생활만족도가 낮으며 자녀와의 관 계에 대한 만족도가 낮은 집단임을 확인 할 수 있었다. 다음으로 로짓분석 결과, 우울증, 성별, 배우자와의 관계 만족도, 자녀와의 관계 만족도, 여가생활 만족도가 고령자 자살위험의 유의미한 영향요인임을 확인하였다. 마지막으로 신경망 분석 결과 1개의 은닉층과 3개의 은닉마디가 도출되었다. 각 모형 간 비교결과, 의사결정나무모형의 오분류율이 로 짓분석과 신경망분석 오분류율보다 낮아, 의사결정나무 모형이 고령자 자살위험 영향요인 도출 및 예측에 더 우수함을 확인할 수 있었다. 반면, ROC인덱스 값은 로짓분석과 신경망 분석이 의사결정나무분석보다 우수한 것으로 나타났다. 이상의 분석결과에 근거하여, 본 연구에서는 고령자의 자살을 예방하기 위한 정책적 함의를 제시하여 향후 관련 정책설계 및 대응방안 구축에 기여하고자 한다. The analysis to predict the suicidal risk among the elderly by methods of Data Mining was conducted in this research. Especially, the research tried to discover the predictive factors of elderly suicidal risks and the interaction pattern among the factors by Decision Tree Analysis, Logit Analysis Model and Artificial Neural Network Analysis. Furthermore, the research aimed to suggest the reason for developing customized solutions to respond properly to the various situation and features of each individuals. As a result of the Decision Tree Analysis, the degree of depression affects the suicidal risk of elderly, and the degree of satisfaction to the housing environment is a important predictive factor following the degree of depression. Also, when the elderly who suffer from the depression with low level of satisfaction to the housing environment is not satisfied with the leisure, the risk of suicide increase. Moreover, the group retaining highest risk of suicide is featured by following factors: high degree of depression, low degree of housing and leisure satisfaction, and low satisfaction of the relation with children. Nextly, according to the result of Logistic Analysis, depression, gender, satisfaction of relationship with spouse, satisfaction of relationship with children and leisure satisfaction affect the elderly suicidal risk significantly. Lastly, as a result of Artificial Neural Network Analysis, one hidden layer and three hidden nodes were identified. The Decision Tree Analysis was identified as a better model for detecting and predicting factors affecting the elderly suicidal risk, because it shows lower misclassification rate compared to the Logistic Analysis and Artificial Neural Network Analysis. However, Logistic Analysis and Artificial Neural Network Analysis have better ROC indices compared to the ROC index of Decision Tree Analysis. Based on the research results, this research aims to contribute to the policy design and solution building in the future by suggesting policy implications to prevent the suicide of the elderly.

자동차 실내 열부하 저감을 위한 태양에너지 응용기술 검토에 관한 연구

이대웅(Daewoong Lee),장길상(Gilsang Jang),오동훈(Donghoon Oh),조경석(Kyungseok Cho),김용철(Yongchul Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

The aim of this paper is to investigate solar energy application for reducing cabin thermal load. When the vehicle parked under the sun in summer, interior temperature is up to 70℃ which is depend on solar intensity. So, solar, one of the alternative energy considered as vehicle thermal comfort solutions, and conducted vehicle cabin thermal load accumulation with forced ventilation for solar energy simulation. Only operating of the air handling system blower by using external power supply, average temperature of cabin room reduced about over 10℃ to 20℃. Means, cabin thermal comfort is improved without extra energy consumption in the vehicle, and cool down performance of air-conditioning system will is better than current vehicle. Moreover fuel economy will be increased due to less air-conditioning system operating and have many opportunities of human advantage such as minimized VOCs by suppling clean air to cabin and healthy cabin environment by dehumidification of evaporator.

자동차 공조 시스템에서 중량 저감을 위하여 1.2t 두께를 갖는 AHU의 개발

이대웅(Daewoong Lee),윤정훈(Junghoon Yun) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.9

Recent trends in vehicle development have gradually been focused on fuel consumption and tailpipe emission. The greenhouse gas(GHG) regulations require a reduction in emission of roughly 30 % for the next 10 years. As a result, the automotive industry has a major challenge to enhance the fuel economy each year. In order to improve fuel economy, one of the solutions is to reduce the weight of the vehicle not only in the chassis parts, but also in the cabin components. Therefore, an attempt has been made to meet those requirements by developing an air handling unit(AHU) housing with a thickness of 1.2. For successful tooling, CAE analysis to implement an AHU housing with a thickness of 1.2 has been performed, taking into account both dynamic stiffness and injection mold flow analysis. Meanwhile, AHU housing mold for mass production was developed as optimized, taking into account the gate number, filling time, injection pressure and temperature, clamping force, volumetric shrinkage and deformation, and the mass product of AHU. Subsequently, the product made from mold met the engineering specification and design criteria through a radiated sound experiment. In this study, an AHU with a thickness of 1.2 was successfully developed by optimizing the mold structure and injection molding conditions, and attained the same dynamic stiffness and radiation sound as the current AHU housing with a thickness of 1.7 while reducing the weight by approximately 20 %.

HEV 동력계/배터리 냉각용 BLDC모터 및 배터리 냉각용 다익 원심팬 개발

이대웅(Daewoong Lee),권대복(Daebok Kwon),지용준(Yongjun Jee),박창호(Changho Park) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2007 No.11

자동차 냉각수 폐열회수 열전발전 시스템의 성능에 관한 연구

이대웅(Dae-Woong Lee) 대한설비공학회 2014 설비공학 논문집 Vol.26 No.7

This study indicated the possibility of energy regeneration from waste coolant heat, by using thermoelectric generation integrated with heat pipe. The internal combustion engine rejects more than 60% wasteful energy to the atmosphere by heat. The thermoelectric generator has recently been studied, to convert the energy from engine waste heat into electricity. For coolant waste heat recovery, a thermoelectric generator was investigated, to find out the possibility of vehicular application. Performance characteristics were conducted with various test conditions of coolant temperature, coolant mass flow rate, air temperature, and air velocity, with the thermoelectric generator installed either horizontally or vertically. Experimental results show that the electric power and conversion efficiency increases according to the temperature difference between the hot and cold side of the thermoelectric generator, and the coolant flow rate of the hot side heat exchanger. Performance improvement can be expected by optimizing the heat pipe design.