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Kim, Wan Sik,Anoop, Gopinathan,Jeong, Il-Seok,Lee, Hye Jeong,Kim, Hyun Bin,Kim, Soo Hyeon,Goo, Gi Won,Lee, Hyunmyung,Lee, Hyeon Jun,Kim, Chingu,Lee, Joo-Hyoung,Mun, Bongjin Simon,Park, Ji-Woong,Lee, E Elsevier 2020 Nano energy Vol.67 No.-
<P><B>Abstract</B></P> <P>For next-generation energy harvesting thermoelectric (TE) devices based on organic/inorganic composites, the barrier energy at interfaces of components is critical in determining the TE performances, because the barrier energy can directly enhance Seebeck coefficient (<I>S</I>). We have succeeded in precisely tuning the barrier energy in poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS)/Bi<SUB>2</SUB>Te<SUB>3</SUB> nanowires (NWs) based organic/inorganic nanocomposite films through polar solvent vapor annealing (PSVA). Controlling the PSS/PEDOT ratio as a function of PSVA duration, the work function of PEDOT:PSS was tuned, which eventually varied the barrier energy of nanocomposite thin films. Through optimization of Bi<SUB>2</SUB>Te<SUB>3</SUB>/PEDOT:PSS barrier energy, the <I>S</I> was maximized up to 47 μV/K. The electrical conductivity was also maximized simultaneously, because of the PSVA-induced <I>π-π</I> stacking among PEDOT chains and templating effect. Density functional theory calculated an optimal barrier energy (0.12 eV), which showed an excellent agreement with our experimentally determined optimal barrier energy (0.11 eV), at which we also maximized the power factor—an efficiency indicator of TE performance. Our feasible strategy on the manipulation of barrier energy in PEDOT:PSS/Bi<SUB>2</SUB>Te<SUB>3</SUB> NWs through the PSVA can be extended to other organic/inorganic based TE composites, toward the realization of highly efficient TE devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We tuned the barrier energy of PEDOT:PSS/Bi<SUB>2</SUB>Te<SUB>3</SUB> nanowires through simply varying the PSVA duration. </LI> <LI> Simultaneous enhancement of Seebeck and electrical conductivity is achieved by optimizing the barrier energy. </LI> <LI> We achieved a power factor maximum of 223 μW/mK<SUP>2</SUP> when the barrier energy, Δ<I>E</I>=0.11 eV, at PSVA duration for 120 min. </LI> <LI> The optimized barrier energy for the enhanced Seebeck coefficient agrees well with the DFT calculated Δ<I>E</I> of 0.12 eV. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Design Principle of Fe-N-C Electrocatalysts: How to Optimize Multimodal Porous Structures?
Lee, Soo Hong,Kim, Jiheon,Chung, Dong Young,Yoo, Ji Mun,Lee, Hyeon Seok,Kim, Min Jeong,Mun, Bongjin Simon,Kwon, Soon Gu,Sung, Yung-Eun,Hyeon, Taeghwan American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.5
<P>The effect of porous structures on the electrocatalytic activity of N-doped carbon is studied by using electrochemical analysis techniques and the result is applied to synthesize highly active and stable Fe-N-C catalyst for oxygen reduction reaction (ORR). We developed synthetic procedures to prepare three types of N-doped carbon model catalysts that are designed for systematic comparison of the porous structures. The difference in their catalytic activity is investigated in relation to the surface area and the electrochemical parameters. We found that macro- and mesoporous structures contribute to different stages of the reaction kinetics. The catalytic activity is further enhanced by loading the optimized amount of Fe to prepare Fe-N-C catalyst. In both N-doped carbon and Fe-N-C catalysts, the hierarchical porous structure improved electrocatalytic performance in acidic and alkaline media. The optimized catalyst exhibits one of the best ORR performance in alkaline medium with excellent long-term stability in anion exchange membrane fuel cell and accelerated durability test. Our study establishes a basis for rationale design of the porous carbon structure for electrocatalytic applications.</P> [FIG OMISSION]</BR>
Bongjin Lee,Jun-Yeop Lee 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
For the release of the nuclear power plant site after the decommissioning, a reliable exposure dose assessment considering the environmental impact of residual radionuclides is essentially required. In this study, the Derived Concentration Guideline Level (DCGL) for the hypothetically contaminated surface soil at the Wolsong nuclear power plant (NPP) unit 1 site was preliminarily calculated by using the RESRAD-OFFSITE computational code and compared with the other case studies. Moreover, radiation exposure dose for local residents and relevant exposure pathways were quantitatively analyzed based on the calculation model established through this work. For the target site modeling, the source term was determined by referring to the previous case studies regarding the nuclear power plant decommissioning, quantification analysis data of pressure tubes of Wolsong NPP unit 1, and radionuclide data estimated by using the MCNP/ORIGEN-2 code. In total, 14 different radioisotopes such as Ag-108m, C-14, Co-60, Cs-134/137, Fe-55, H-3, Nb-93m/94, Ni-63, Sb-125, Sn-121m, Sr-90, and Zr-93 were considered as target radionuclides. In addition, the geological structure model of the Wolsong NPP site was established based on the final safety analysis report of Wolsong NPP unit 1. The distribution coefficients (Kd) were taken from the JAEA-SDB to estimate the migration/retardation behavior of various radionuclides under the groundwater condition of the Wolsong NPP site. In the present work, the DCGL values were calculated according to the site release criterion of 0.1 mSv/yr, which indicates the radiation protection standard for the site release. Moreover, the exposure pathway and sensitivity analyses were conducted to assess the sensitive input parameters remarkably influencing the calculation result. For the evaluation of exposure dose for local residents, a site layout centered around Wolsong NPP unit 4, located in the closest proximity to the residents’ habitation area, was alternatively established and all potential exposure pathways were considered as a comprehensive resident farmer scenario. The results obtained from this study are expected to serve as a preliminary case study for the DCGL values regarding the surface soil at the Wolsong NPP unit 1 site and for evaluating the radiation exposure dose to local residents resulting from the residual radioactivity at the site after the decommissioning.
Pediatric triage modifications based on vital signs: a nationwide study
Lee Bongjin,Park June Dong,Kwak Young Ho,Kim Do Kyun 대한응급의학회 2022 Clinical and Experimental Emergency Medicine Vol.9 No.3
Objective To analyze the clinical significance of a heart rate (HR) or respiratory rate (RR) higher or lower than the normal in pediatric triage. Methods A retrospective observational study was conducted with data from the Korean National Emergency Department Information System. The subjects were children <15 years of age in 2016. Reported HRs and RRs were divided into seven groups: grade -3 (3 or more standard deviations [SDs]<normal), grade -2 (2 SDs<normal), grade -1 (1 SD<normal), grade 0 (normal), grade 1 (1 SD>normal), grade 2 (2 SDs>normal), and grade 3 (3 or more SDs>normal). The main outcomes were hospitalization and intensive care unit (ICU) admission rates. Logistic regression analysis was used to analyze the relationship of the outcomes according to grade in each group. Results Data for 981,297 patients were analyzed. Hospitalization and ICU admission rates increased significantly in the higher HR group (grades 1 to 3; odds ratio [OR], 1.353; P<0.001; OR, 1.747; P<0.001; respectively) and in the higher RR group (OR, 1.144; P<0.001; OR, 1.396; P<0.001; respectively), compared with grade 0 group. In the lower HR group (grades -1 to -3), the hospitalization rate decreased (OR, 0.928; P<0.001), whereas the ICU admission rate increased (OR, 1.207; P=0.001). Although the hospitalization rate increased. In the lower RR group (OR, 1.016; P=0.008), the ICU admission rate did not increase (OR, 0.973; P=0.338). Conclusion Deviations in HR and RR above normal are related to increased risks of hospitalization and ICU admission. However, this association may not apply to deviations below normal.
Bongjin Lee,Hyung Joo Jeong,Yu Hyeon Choi,Chong Won Choi,June Dong Park 대한중환자의학회 2015 Acute and Critical Care Vol.30 No.4
Phacomatosis pigmentovascularis (PPV) is a rare syndrome characterized by concurrent nevus flammeus (capillary malformation) and pigmentary nevus. According to current research, the major pathophysiologic mechanism in PPV is venous dysplasia with resultant compensatory collateral channels and venous hypertension. Arterial involvement is rare. We herein report our experience on renovascular hypertension, intermittent claudication, and severe rhabdomyolysis due to diffuse stenosis of multiple arteries in a patient with PPV type IIb associated with SWS.
이봉진 ( Bongjin Lee ) 한국공업화학회 2019 공업화학전망 Vol.22 No.1
포장이란 사람이 아이를 안전하게 감싸다라는 의미를 가진 ‘포’자와 겉을 아름답게 꾸민다는 의미의 ‘장’자가 합쳐져 만들어진 단어로 포장은 보호성, 편리성, 심미성 3가지의 목적과 기능을 가져야 한다. 세계 포장 시장은 약 1,030조원 규모이며, 국내 포장재 시장은 플라스틱 연포장(비닐포장), 용기, 지류, 금속 등 44조 2000억 원 규모로 매년 3% 이상 성장 중이다. 식품 포장은 이 중 55%를 차지하고 있으며, 과거 주로 일본 포장 전문 회사의 노하우를 채택하였지만 최근에는 한식에 맞는 포장법에 대한 연구와 개발이 활발해지고 있다. 또한 1인 가족, 핵가족, 맞벌이, 노령화 등 한국 사회의 가구 형태 변화로 개별 포장의 필요성에 따라 식품 분야 포장 산업의 성장세가 급증하고 있다. 한편 식품 산업은 부가가치 창출이 최우선되는 4차 산업혁명의 가장 핵심적인 산업이 될 것이라는 통계가 나오고 있으므로 성장 가능성이 높다고 전망되고 있다. 현재는 새로운 푸드테크, 소재 개발, 소재 도입이 중요한 시기로 여겨지고 있다. 따라서 본 기고에서는 글로벌 시장에서 새롭게 떠오르고 있는 식품 포장재 기술의 발전 방향과 시장 성장 단계 및 동향을 제시하고자 한다.