신뢰성 향상을 위한 지상기동체계 내구성평가 방안 연구

정덕재(Deokjae Jung),연재성,정도현(Dohyun Jung),Jaejeong Han 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5

Embedded Metal Electrode for Organic–Inorganic Hybrid Nanowire Solar Cells

Um, Han-Don,Choi, Deokjae,Choi, Ahreum,Seo, Ji Hoon,Seo, Kwanyong American Chemical Society 2017 ACS NANO Vol.11 No.6

<P>We demonstrate here an embedded metal electrode for highly efficient organic inorganic hybrid nanowire solar cells. The electrode proposed here is an effective alternative to the conventional bus and finger electrode which leads to a localized short circuit at a direct Si/metal contact and has a poor collection efficiency due to a nonoptimized electrode design. In our design, a Ag/SiO2 electrode is embedded into a Si substrate while being positioned between Si nanowire arrays underneath poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), facilitating suppressed recombination at the Si/Ag interface and notable improvements in the fabrication reproducibility. With an optimized microgrid electrode, our 1 cm(2) hybrid solar cells exhibit a power conversion efficiency of up to 16.1% with an open-circuit voltage of 607 mV and a short circuit current density of 34.0 mA/cm(2). This power conversion efficiency is more than twice as high as that of solar cells using a conventional electrode (8.0%). The microgrid electrode significantly minimizes the optical and electrical losses. This reproducibly yields a superior quantum efficiency of 99% at the main solar spectrum wavelength of 600 nm. In particular, our solar cells exhibit a significant increase in the fill factor of 78.3% compared to that of a conventional electrode (61.4%); this is because of the drastic reduction in the metal/contact resistance of the 1 mu m-thick Ag electrode. Hence, the use of our embedded microgrid electrode in the construction of an ideal carrier collection path presents an opportunity in the development of highly efficient organic inorganic hybrid solar cells.</P>

ITO-free carrier-selective contact for crystalline silicon solar cells

Choi, Deokjae,Yoon, Hyun,Kim, Ka-Hyun,Um, Han-Don,Seo, Kwanyong The Royal Society of Chemistry 2019 Journal of materials chemistry. A, Materials for e Vol.7 No.5

<P>In this study, an indium tin oxide (ITO)-free carrier-selective contact (CSC) for crystalline silicon (c-Si) solar cells with a micro-grid metal electrode is reported. The ITO layer is crucial for collecting the carriers separated at the junction between CSC and n-Si because of the relatively low conductivity of CSC. However, previous research investigated the formation of ITO films <I>via</I> sputter deposition, which can lead to performance degradation of solar cells due to the parasitic absorption of the ITO layer and plasma damage at the CSC/Si junction during sputtering. Moreover, the use of ITO is hindered because of the rare indium metal. Herein, we investigate the carrier transport mechanism at the MoOx/n-Si junction to understand the reason for the poor performance of ITO-free devices. A majority of the carriers are limited because of a highly resistive carrier path, with a sheet resistance of 16 kΩ sq<SUP>−1</SUP> during carrier transport, leading to the severe degradation of fill factor (FF) and short-circuit current (<I>J</I>sc). To minimize the power loss during carrier transport, a micro-grid metal electrode that can effectively collect carriers separated at the MoOx/n-Si junction is applied. With this micro-grid electrode, the electrical losses of ITO-free solar cells can be minimized despite the highly resistive path of the MoOx/n-Si junction. Hence, the best device exhibits a power conversion efficiency of up to 17.0% without the ITO layer.</P>

지상기동체계의 조기 내구신뢰성 확보에 관한 연구

정덕재(Deokjae Jung),한재정(Jaejeong Han),정도현(Dohyun Jung) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5

Diagnostic index for acute eosinophilic pneumonia without bronchoscopy in military smokers

( Sunmin Park ),( Deokjae Han ),( Ji Eun Lee ),( Duck Hyun Ryu ),( Hyung-jun Kim ) 대한내과학회 2022 The Korean Journal of Internal Medicine Vol.37 No.2

Background/Aims: Acute eosinophilic pneumonia (AEP) is common among military smokers; however, bronchoscopy is required for the diagnosis. We aimed to derive and validate a scoring system to diagnose AEP without bronchoscopy. Methods: We conducted a retrospective study including patients diagnosed with AEP or any other pneumonia among military smokers hospitalized in the Armed Forces Capital Hospital from 15 November 2016 through 25 December 2019. The patients were divided into derivation and validation groups according to their admission day. Patient symptoms, laboratory findings, and computed tomography findings were candidate variables. Least absolute shrinkage and selection operator (LASSO) regression was used to calculate the scores for each variable. Results: Among 414 patients, AEP was confirmed in 54 of 279 patients (19.4%) in the derivation group and in 18 of 135 patients (13.3%) in the validation group. Ten variables were selected using LASSO regression: new-onset or a recently increased smoking (≤ 4 weeks) (8 points), interlobular septal thickening (5 points), absence of sputum (3 points), ground glass opacity (3 points), acute onset (≤ 3 days) (2 points), dyspnea (2 points), chest pain (2 points), leukocytosis (2 points), bronchovascular bundle thickening (2 points), and bilateral involvement (2 points). The area under the receiver-operating characteristic curve of the score to diagnose AEP was 0.997 (95% confidence interval, 0.992 to 1.000) in the derivation group and 0.985 (95% confidence interval, 0.965 to 1.000) in the validation group. Conclusions: We introduce a scoring system that can distinguish AEP from other types of pneumonia in military smokers without the need for bronchoscopy.

Incidence of Adverse Effects and Discontinuation Rate between Patients Receiving 250 Micrograms and 500 Micrograms of Roflumilast: A Comparative Study

Joo, Hyonsoo,Han, Deokjae,Lee, Jae Ha,Rhee, Chin Kook The Korean Academy of Tuberculosis and Respiratory 2018 Tuberculosis and Respiratory Diseases Vol.81 No.4

Background: Roflumilast is the only approved oral phosphodiesterase-4 inhibitor for the treatment of severe chronic obstructive pulmonary disease (COPD) in patients with chronic bronchitis and a history of frequent exacerbations. The purpose of this study was to examine the incidence of adverse effects associated with roflumilast treatment in a real-world setting. Further, we compared the incidence of adverse effects and the discontinuation rate among patients receiving different doses. Methods: We identified all outpatients diagnosed with COPD at Seoul St. Mary's Hospital between May 2011 and September 2016 and retrospectively reviewed their medical records. Roflumilast was prescribed to patients in doses of $500{\mu}g$ and $250{\mu}g$. Results: A total of 269 COPD patients were prescribed roflumilast in our hospital during the study period. Among them, 178 patients were treated with $500{\mu}g$ and 91 patients were treated with $250{\mu}g$. The incidence of adverse effects was 38.2% in the $500{\mu}g$ group and 25.3% in the $250{\mu}g$ group (p=0.034). The discontinuation rate of roflumilast was 41.6% (n=74) in the $500{\mu}g$ group and 23.1% (n=21) in the $250{\mu}g$ group (p=0.003). When adjusted by age, sex, smoking status, and lung function, $500{\mu}g$ dose was significantly associated with the discontinuation of roflumilast (odds ratio, 2.87; p<0.001). Conclusion: There was a lower incidence of adverse effects and discontinuation among patients treated with $250{\mu}g$ compared with $500{\mu}g$ dose. Further studies regarding the optimal dose of roflumilast are required.

Incidence of Adverse Effects and Discontinuation Rate between Patients Receiving 250 Micrograms and 500 Micrograms of Roflumilast: A Comparative Study

( Hyonsoo Joo ),( Deokjae Han ),( Jae Ha Lee ),( Chin Kook Rhee ) 대한결핵 및 호흡기학회 2018 Tuberculosis and Respiratory Diseases Vol.81 No.4

Background: Roflumilast is the only approved oral phosphodiesterase-4 inhibitor for the treatment of severe chronic obstructive pulmonary disease (COPD) in patients with chronic bronchitis and a history of frequent exacerbations. The purpose of this study was to examine the incidence of adverse effects associated with roflumilast treatment in a real-world setting. Further, we compared the incidence of adverse effects and the discontinuation rate among patients receiving different doses. Methods: We identified all outpatients diagnosed with COPD at Seoul St. Mary’s Hospital between May 2011 and September 2016 and retrospectively reviewed their medical records. Roflumilast was prescribed to patients in doses of 500 µg and 250 µg. Results: A total of 269 COPD patients were prescribed roflumilast in our hospital during the study period. Among them, 178 patients were treated with 500 µg and 91 patients were treated with 250 µg. The incidence of adverse effects was 38.2% in the 500 µg group and 25.3% in the 250 µg group (p=0.034). The discontinuation rate of roflumilast was 41.6% (n=74) in the 500 µg group and 23.1% (n=21) in the 250 µg group (p=0.003). When adjusted by age, sex, smoking status, and lung function, 500 µg dose was significantly associated with the discontinuation of roflumilast (odds ratio, 2.87; p<0.001). Conclusion: There was a lower incidence of adverse effects and discontinuation among patients treated with 250 µg compared with 500 µg dose. Further studies regarding the optimal dose of roflumilast are required.

Slinky-inspired triboelectric–electromagnetic hybrid generator

Lee Joon-seok,Heo Deokjae,Lyu Han-uk,Hur Ji Woong,Kim Sunghan,Lin Zong-Hong,Park Joong Yull,Lee Sangmin 한국물리학회 2023 Current Applied Physics Vol.49 No.-

Researchers are attempting to develop hybrid generators by integrating several mechanical energy harvesting techniques, although most of them employ complicated device structures and fabrication methods. In this paper, we propose a slinky inspired triboelectric-electromagnetic hybrid generator (S-TEHG) that can easily function as a portable power source for devices used in daily life. This S-TEHG generates a high output using a peak voltage and current output of up to 7.4 V and 83.2 mA, respectively. For practical application as a portable power source in everyday life, the S-TEHG is enclosed (packaged) in an acrylic cylinder. In this study, upon hand waving, the proposed packaged S-TEHG successfully illuminated an array of 15 light-emitting diodes and charged a 47 μF capacitor.

Scoring System to Diagnose Acute Eosinophilic Pneumonia Without Bronchoscopy

( Hyung-jun Kim ),( Sunmin Park ),( Deokjae Han ),( Ji Eun Lee ),( Duck Hyun Ryu ) 대한결핵 및 호흡기학회 2020 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.128 No.-

Purpose Acute eosinophilic pneumonia (AEP) is common among military personnel with smoking habits. Although its progression is rapid, bronchoscopy is mandatory for diagnosis which is sometimes difficult to perform immediately. Therefore, we aim to derive and validate a scoring system that could discriminate AEP from pneumonia without bronchoscopy. Methods Among patients hospitalized to Armed Forces Capital Hospital from November 15th 2016 to December 25th 2019, those diagnosed as either pneumonia or AEP while smoking were selected. Patients who fulfilled the Modified Philit’s criteria were categorized as AEP, and those diagnosed as pneumonia were categorized as pneumonia. Patients were divided into derivation and validation cohorts according to their admission dates. Demographics, comorbidities, symptoms, laboratory, and computed tomography findings were considered candidates for score derivation. Least absolute shrinkage and selection operator (LASSO) analysis was used to select and calculate coefficients of each variable. Coefficients were transformed into scores, and the score’s discrimination performance was calculated by area under the receiver operating characteristics curve (AUROC). Results Among the total of 414 patients, 279 and 135 were allocated to the derivation and validation cohorts, respectively. AEP was confirmed in 72 (17.4%), while 342 (82.6%) were diagnosed as pneumonia. With LASSO, ten variables were selected with corresponding scores: recent (<1 month) initiation of smoking or increase in smoking amount (7), interlobar septal thickening (5), ground glass opacity (2), bronchovascular bundle thickening (2), bilateral involvement (2), leukocytosis (2), dyspnea (2), chest pain (2), lack of sputum (2), and onset within 3 days (1). AUROC of the scoring system was 0.996 (95% confidence interval 0.991-1.000) in the derivation cohort, and 0.986 (95% confidence interval 0.967-1.000) in the validation cohort. Conclusions A scoring system that could discriminate AEP from pneumonia without bronchoscopy is introduced. This can aid in early diagnosis of AEP patients who cannot undergo urgent bronchoscopy.

Predictive Value of Interferon Gamma Release Assay for Incident Active Tuberculosis: 2-year Follow-up Results of TBfreeCorea

( Hyung Woo Kim ),( Ju Sang Kim ),( Jinsoo Min ),( Joon Young Choi ),( Ah Young Shin ),( Deokjae Han ),( Jun-pyo Myong ),( Yunhee Lee ),( Hyeon Woo Yim ),( Hyunsuk Jeong ),( Sanghyuk Bae ),( Eunhye Sh 대한결핵 및 호흡기학회 2020 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.128 No.-

Background The aim of this study was to investigate the predictive value of interferon gamma release assay (IGRA) for incident active tuberculosis (TB). Methods Among the cohort of TBfreeCorea, participants who underwent IGRA in 2017 were followed up until January 2nd, 2020. To investigate the natural history of LTBI, those with negative IGRA Results and those with positive Results but who did not initiate LTBI treatment were included in this study. Sensitivity, specificity and predictive values were investigated with 2-year cumulative TB incidence. Effects of interferon (IFN) level and other risk factors on incident TB cases was analyzed in a Cox proportional hazard model with time varying covariates. Results Among the enrolled 810,294 participants, a total of 570 cases of active TB were identified. Two-year cumulative TB incidence was 62.7 cases per 100,000 population. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 63.39%, 89.44%, 0.38% and 99.97% respectively, with current cutoff value of 0.35 IU/mL. PPV was higher among the young aged group - 0.90% in age group < 20 and 0.96% in age group 20-35. When cutoff value was raised to 0.67, 1.41 and 3.33 IU/ml, PPV were improved to 0.44%, 0.51% and 0.62%, respectively, but sensitivity decreased to 58.46%, 48.62% and 36.81%. In a Cox proportional hazard model, risk of active TB increased with higher IFN level - when compared with IGRA negative group, hazard ratio among the group with IFN level of 0.35-0.67, 0.67-1.41, 1.41-3.33, 3.33-10.0 and > 10 IU/ml was 6.56 (4.29-10.03), 13.38 (9.56-18.73), 18.15 (13.19-24.99), 31.81 (24.01-42.16), 43.51 (32.21-58.79), respectively. In a subgroup analysis stratified by age, such tendency was more prominent in younger age group, whereas obscured in elderly group. Conclusions IGRA showed quantitative predictive value for TB incidence, especially among young age group. However, low PPV remains a limitation.