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Electrochemical ammonia (NH3) production, an alternative to the energy-intensive Haber process, has been extensively studied based on the basis of N2 fixation; a high-yield production is hindered b...

Background: Congenital diaphragmatic hernia (CDH) is a rare disease often requiring mechanical ventilation after birth. In severe cases, extracorporeal membrane oxygenation (ECMO) may be needed. This study analyzed the outcomes of patients with CDH treated with ECMO and investigated factors related to in-hospital mortality. Methods: Among 254 newborns diagnosed with CDH between 2008 and 2020, 51 patients needed ECMO support. At Asan Medical Center, a multidisciplinary team approach has been applied for managing newborns with CDH since 2018. Outcomes were compared between hospital survivors and nonsurvivors. Results: ECMO was established at a median of 17 hours after birth. The mean birth weight was 3.1±0.5 kg. Twenty-three patients (23/51, 45.1%) were weaned from ECMO, and 16 patients (16/51, 31.4%) survived to discharge. The ECMO mode was veno-venous in 24 patients (47.1%) and veno-arterial in 27 patients (52.9%). Most cannulations (50/51, 98%) were accomplished through a transverse cervical incision. No significant between-group differences in baseline characteristics and prenatal indices were observed. The oxygenation index (1 hour before: 90.0 vs. 51.0, p=0.005) and blood lactate level (peak: 7.9 vs. 5.2 mmol/L, p=0.023) before ECMO were higher in nonsurvivors. Major bleeding during ECMO more frequently occurred in nonsurvivors (57.1% vs. 12.5%, p=0.007). In the multivariate analysis, the oxygenation index measured at 1 hour before ECMO initiation was identified as a significant risk factor for in-hospital mortality (odds ratio, 1.02; 95% confidence interval, 1.01–1.04; p=0.05). Conclusion: The survival of neonates after ECMO for CDH is suboptimal. Timely application of ECMO is crucial for better survival outcomes.

The degradation of amorphous cobalt phosphides (CoPx) as an electrocatalyst for the hydrogen evolution reaction (HER) is studied in the discontinuous operation of alkaline water electrolysis cells (AWEs). Although amorphous CoPx shows a 100-fold enhancement in HER activity over nickel, the kinetic current for the HER is decreased after discontinuous operation. Under the off condition, the cathode potential of the AWE increases close to the equilibrium potential for CoPx oxidation to Co, Co(OH)2, CoOx, and CoPxOy. The irreversible oxide and hydroxide formation induces weaker interactions between Co and P, and thus the degradation of kinetics over CoPx, negatively affecting the HER even though a cathodic current is applied for recovery. A cathodic protection method is devised to mitigate the degradation of CoPx by shifting the electrode potential below the equilibrium potential of Co(OH)2. Mn is chosen as a sacrificial species, and it slows the rate of electrode degradation by negative polarization of the electrode. The results show that the co-deposition of even a small amount of Mn onto the CoPx electrode could limit the loss of HER activity during repeated discontinuous operation of the AWEs. Furthermore, in situ X-ray absorption near edge structure analysis confirms that the CoPx with co-deposited Mn does show the effect on holding the phase of CoPx during discontinuous operation.

Background This study aimed to assess the effect of vessel size and flow characteristics on the maturation of autogenous radiocephalic arteriovenous fistulae (RCAVFs). Methods We retrospectively reviewed records of patients undergoing RCAVF creation at a single medical center from January 2013 to December 2019. Operative variables were compared between patients whose fistulae matured and those whose fistulae failed to mature. Results Overall, 152 patients (33 of whom were women) with a mean age of 62.6±13.6 years underwent RCAVF creation; functional maturation was achieved in 123. No statistically significant differences were observed between patients in whom maturation was or was not achieved in terms of the following variables: female sex (20.3% vs. 25.0%), radial artery size (2.5 vs. 2.4 mm), and pulsatility index (0.69 vs. 0.62). Low intraoperative transit time flowmetry (TTF; 150.4 vs. 98.1 mL/min) and small vein size (2.4 vs. 2.0 mm) were associated with failure of maturation. The best cutoff diameter for RCAVF TTF and cephalic vein size were 105 mL/min and 2.45 mm, respectively. Conclusion In patients who undergo RCAVF creation, vein diameter on preoperative ultrasonography and intraoperative TTF are predictors of functional maturation. We identified an intraoperative TTF cutoff value that can be used for intraoperative decision-making.

Hydrogen is nowadays considered a favorable and attractive energy carrier fuel to replace other fuels that cause global warming problems. Water electrolysis has attracted the attention of researchers to produce green hydrogen mainly for the accumulation of renewable energy. Hydrogen can be safely used as a bridge to successfully connect the energy demand and supply divisions. An alkaline water electrolysis system owing to its low cost can efficiently use renewable energy sources on large scale. Normally organic/inorganic composite porous separator membranes have been employed as a membrane for alkaline water electrolyzers. However, the separator membranes exhibit high ionic resistance and low gas resistance values, resulting in lower efficiency and raised safety issues as well. Here, in this study, we report that zirconia toughened alumina (ZTA)–based separator membrane exhibits less ohmic resistance 0.15 Ω·cm2 and low hydrogen gas permeability 10.7 × 10−12 mol cm−1 s−1 bar−1 in 30 wt.% KOH solution, which outperforms the commercial, state-of-the-art Zirfon® PERL separator. The cell containing ZTA and advanced catalysts exhibit an excellent performance of 2.1 V at 2000 mA/cm2 at 30 wt.% KOH and 80 °C, which is comparable with PEM electrolysis. These improved results show that AWEs equipped with ZTA separators could be superior in performance to PEM electrolysis.

Kim, H.-J.; Cho, W.C., and Moon, Y.-H., 2021. Comparative analysis on wave field using wave measurement and wave analysis data from JMA-MSM. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 181–185. Coconut Creek (Florida), ISSN 0749-0208. Waves are the most important factor in the numerical analysis of coastal hydrodynamics. Wave conditions in coastal areas can be determined in on-site wave measurements or wave numerical analyses. Because the acquisition of spatial wave measurement data in a specific coastal area is limited, the spatial wave data are generally acquired with accurate numerical analyses. In this study, the wave field in a coastal area in South Korea was comparatively analyzed with wave measurements and numerical analyses of wind data acquired with the JMA (Japan Meteorological Agency) Meso-Scale Model (MSM). The high-resolution meteorological data were used for the numerical analysis, and the wave measurement data provided by the Wave Information Network of Korea (WINK) were used for the comparative analysis. Results showed the root mean square errors of 0.3-0.4m for all wave prediction in the East Sea in 2018 and 0.4-0.5m for typhoon KONG-REY in 2018. Therefore, it was concluded that the wave numerical simulations based on the wave data from JMA-MSM overall reproduced the wave field accurately.

Lee, D.S.; Cho, W.C., and Lee, K.J., 2021. Experimental study on estimation of water level rise behind a low-crested structure using water level-discharge relationship. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 11–15. Coconut Creek (Florida), ISSN 0749-0208. Low-crested structures (LCSs) that are installed to reduce the incoming wave height, such as detached and submerged breakwater structures, allow more overflow than do general breakwater structures and increase the water level behind the structure. In the LCS design stage, because the increased water level distorts the results of laboratory experiments, the effect of the rise in the water level must be determined. In this study, an experiment was conducted to determine the water level-discharge relationship and analyze the characteristics of the water level rise behind permeable and impermeable LCSs with various wave conditions. It is found that the slopes of the water level-discharge relationship with the same significant wave period are approximately identical for the permeable and impermeable LCSs. In addition, the slopes of the water level-discharge relationship for different significant wave heights are linear for the permeable LCSs but not for the impermeable LCSs. These results can be useful for selecting a suitable planar configuration for LCSs in field site applications.

Economic uncertainty analysis of employing a membrane reactor (MR) equipped with H2O separation membranes for a synthetic natural gas (SNG) production as simultaneous power-to-gas and CO2 utilization technologies was carried out. Based on previously reported reaction kinetics, process simulation models were created for a conventional packed-bed reactor (PBR) and an MR. Deterministic economic analysis showed the unit SNG production cost of 1.67 $ kgSNG−1 in an MR compared to 1.82 $ kgSNG−1 in a PBR for a SNG production capacity of 1000 kg d−1, showing about 8% cost reductions in the MR. From sensitivity analysis, raw material and labor were identified as the key economic factors to affect a unit SNG production cost for all cases studied. Stochastic economic analysis using a Monte-Carlo simulation method provided better insights for economic-uncertainty associated with premature technology like a SNG production in an MR using H2O separation membranes by presenting a wide range of SNG production costs and their probability.

Water electrolysis for hydrogen and oxygen production is a key technology in next-generation energy carrier and conversion. In particular, renewable energy sources integrated water electrolysis system has emerged due to its eco-friendly and highly energy efficient process. However, inherent limitations of renewable energy sources including intermittent and unpredictable energy production restrict stable water electrolysis cell operating. Therefore, investigation on cell performance depending on various operation conditions is absolutely required. Here, we synthesized Ni-Fe layered double hydroxide (Ni-Fe LDH) electrodes and studied their oxygen evolution reaction (OER) activities under various operational conditions matching actual environmental conditions when utilizing renewable energy sources. Changes in morphology and electrocatalytic performance were systematically studied by using XRD, FE-SEM, and EIS measurement. Our results showed that operation of water electrolysis cell in an accelerated stress condition could result in changes in morphology of crystal structure of LDH, thus restricting ions to be fully utilized at active site for OER.

The international nuclear industry has undergone a lot of changes since the Fukushima, Chernobyl and TMI nuclear power plant accidents. However, there are still large and small component deficiencies at nuclear power plants in the world. There are many causes of electrical equipment defects. There are also factors that cause component failures due to human errors. This paper analyzed the root causes of failure and types of human error in 300 cases of electrical component failures. We analyzed the operating experience of electrical components by methods of root causes in K-HPES (Korean-version of Human Performance Enhancement System) and by methods of human error types in HuRAM+ (Human error-Related event root cause Analysis Method Plus). As a result of analysis, the most electrical component failures appeared as circuit breakers and emergency generators. The major causes of failure showed deterioration and contact failure of electrical components by human error of operations management. The causes of direct failure were due to aged components. Types of human error affecting the causes of electrical equipment failure are as follows. The human error type group Ⅰ showed that errors of commission (EOC) were 97%, the human error type group Ⅱ showed that slip/lapse errors were 74%, and the human error type group Ⅲ showed that latent errors were 95%. This paper is meaningful in that we have approached the causes of electrical equipment failures from a comprehensive human error perspective and found a countermeasure against the root cause. This study will help human performance enhancement in nuclear power plants. However, this paper has done a lot of research on improving human performance in the maintenance field rather than in the design and construction stages. In the future, continuous research on types of human error and prevention measures in the design and construction sector will be required. Keywords: Human performance, Human error type, Root cause, Electrical component failure

An iron-based oxygen carrier can convert natural gas into chemicals (syngas or hydrogen) with controlled CO2 emission in a redox process. Mixed ionic-electronic conductor (MIEC)-supported iron oxides have shown high catalytic activity by facilitating inward O anion diffusion. However, their durability has been tested under limited conditions, and key factors affecting the degradation of MIEC-supported iron oxides have rarely been identified. In this work, we find that the inherent redox stability and electronic conductivity of the support material are decisive properties that determine the redox stability and activity of iron oxide/MIEC composites, such as perovskite-type La0.8Sr0.2FeO3−δ and fluorite-type Ce0.9Gd0.1O2−δ, over 100 redox cycles with the redox pair Fe – Fe2O3 at 900 °C. The low redox stability of the Fe2O3/La0.8Sr0.2FeO3−δ composite oxygen carrier is closely related to that of La0.8Sr0.2FeO3−δ and the extreme redox environment. The increased electronic conductivity of Ce0.9Gd0.1O2−δ under reducing conditions enhances the reaction rate. However, the low electronic conductivity of Ce0.9Gd0.1O2−δ under oxidizing conditions (5 × 10−4 S/cm at 750 °C) progressively promotes the formation of iron oxide product layer, resulting in low syngas selectivity (H2/CO > 2). This work helps design and select a compatible and commercially viable MIEC-supported iron oxide.

A photovoltaic–electrolysis–PEM hybrid model was developed for a feasibility study, and simulations of several scenarios in Korea were performed. The solar irradiance was derived from the University of Arizona solar irradiance based on satellite–Korea Institute of Energy Research model which provides the satellite imagery over the Korean peninsula every 15 min. In Korea, the annual average solar irradiance is 1,310 kWh m−2 with a maximum of 1,440 kWh m−2 in 2017. Electricity load and solar irradiance information were used to test the performance model of the photovoltaic–electrolysis–PEM hybrid system for baseload and several peak load shave runs. When the baseload was set at 4200 MW, the total capacity of the Photovoltaic plants was 58.5 GWp. In contrast, the hybrid system reduced the peak load more efficiently during daytime. In particular, the capacity factor of the Proton Exchange Membrane system increased in winter because the solar irradiance is relatively weak in that season. These results provide useful insights for the development of control logic models for the PV–electrolysis–PEM system in micro-grid setups.

Thoracic endovascular aortic repair has been preferred over surgery for aortic lesions owing to its minimal invasiveness. Here we report the successful endovascular repair of a thoracic aortic pseudoaneurysm after esophageal perforation induced by accidental ingestion of a fishbone.

Refereed/Peer-reviewed Hierarchical porous carbon (HPC) materials have found advanced applications in energy storage, adsorption, and catalysis in recent years. The HPC can be synthesized from a vast range of inexpensive carbon precursors, and contain unique structural features, such as nano-scale dimension, high porosity, high surface area, and tunable pore surfaces. These materials hold immense potential for removing contaminants from water and wastewater. However, this area is severely under-explored yet. In this review, we have discussed the recent advances of synthesis, modification, and application of HPC for the removal of pollutants from water, especially focusing on organic pollutants. Owing to their intrinsic hydrophobic nature and unique interconnected porous structure, HPC demonstrates a high affinity to hydrophobic organic contaminants, which can be enhanced many folds by target-specific chemical activation. Successful high-performance removal of contaminants by pristine and modified HPC includes plastic-derived (e.g. bisphenol A), pharmaceutical (e.g. antibiotics), dye (e.g. methylene blue) and pesticide micro-pollutants. Future research is warranted to find optimal and effective HPC synthesis and modification methods for further improving their ability to remove aqueous organic contaminants as a low-cost and energy-inexpensive remediation technology.

Extensive energy consumption has become a major concern due to increase of greenhouse gas emissions and global warming. Hence, hydrogen has attracted attention as a green fuel with zero carbon emission for green transportation through production of electric vehicles with hydrogen fuel cells. South Korea has launched a hydrogen society policy with the objective of expanding production of hydrogen from renewable energy sources. The hydrogen economy will play a critical role in reducing atmospheric pollution and global warming. However, new development of infrastructure for hydrogen refueling and increasing awareness of the hydrogen economy is required together with reduced prices of hydrogen-driven vehicles that are promising options for a sustainable green hydrogen economy.

Reducing the iridium loading for the oxygen evolution reaction (OER) is one of the main challenges of polymer electrolyte membrane water electrolysis (PEMWE). This study introduces grape-like iridium nanoclusters supported on boron carbide (B4C) which increase iridium utilization compared to a non-supported iridium catalyst. A simple chemical reduction method with NaBH4 as a reducing agent was used to synthesize iridium nanoclusters on B4C. TEM images indicated that grape-like iridium nanoclusters were successfully dispersed on the B4C support. The catalytic performance of Ir/B4C was better than that of a commercial catalyst. To reach a current density of 10 mA/cm2, the overpotential of Ir/B4C was less than that of the commercial catalyst by 32 mV. Ir/B4C also has a mass activity 2.55 times higher than that of the commercial catalyst at 1.55 V. These improvements are attributed to the high electrochemical active surface area, the weak adsorption strength of oxygen, and the presence of Ir(OH)4 on the surface. The durability of Ir/B4C is comparable to that of the commercial catalyst at 1 mA/cm2 for 15 h and higher at 10 mA/cm2 for 3 h. B4C may weaken the oxidative dissolution of iridium by transferring electrons even though the high electrochemical surface area of iridium in Ir/B4C may reduce its durability.

The intermittent and volatile nature of renewable energy sources threatens the stable operation of power grids, necessitating dynamically operated energy storage. Power-to-gas technology is a promising method for managing electricity variations on a large gigawatt (GW) scale. The electrolyzer is a key component that can convert excess electricity into hydrogen with high flexibility. Recently, organic/inorganic composite separators have been widely used as diaphragm membranes, however, they are prone to increase ohmic resistance and gas crossover, which inhibit electrolyzer efficiency. Here, we show that the ceria nanoparticle and polysulfone composite separator exhibits a low area resistance of 0.16 &Omega, cm2 and a hydrogen permeability of 1.2 &times, 10&ndash, 12 mol cm&ndash, 1 s&ndash, 1 bar&ndash, 1 in 30 wt% potassium hydroxide (KOH) electrolyte, which outperformed the commercial separator, the Zirfon PERL separator. The cell using a 100 nm ceria nanoparticle/polysulfone separator and advanced catalysts has a remarkable capability of 1.84 V at 800 mA cm&minus, 2 at 30 wt% and 80 &deg, C. The decrease in the average pore size of 77 nm and high wettability (contact angle 75&deg, ) contributed to the reduced ohmic resistance and low gas crossover. These results demonstrate that the use of ceria nanoparticle-based separators can achieve high performance compared to commercial zirconia-based separators.

Giant coronary artery aneurysms are rare and challenging to treat because of variation in the presenting symptoms and the lack of established management guidelines. We report the case of a patient with a 6-cm-wide giant coronary artery aneurysm that was resected, followed by reconstruction using a saphenous vein graft and 18 years of follow-up.

Background The primary goal of this study was to characterize the clinical outcomes of adult patients with hematologic malignancies (HM) who were treated with extracorporeal membrane oxygenation (ECMO) support when conventional treatments failed. Methods In this retrospective, observational study at a tertiary medical center, we reviewed the clinical course of 23 consecutive patients with HM requiring ECMO who were admitted to the intensive care unit at Asan Medical Center from March 2010 to April 2015. Results A total of 23 patients (8 female; median age, 44 years; range, 29-51 years) with HM and severe acute circulatory and/or respiratory failure received ECMO therapy during the study period. Fourteen patients received veno-arterial ECMO, while 9 patients received veno-venous ECMO. The median ECMO duration was 104.7 hours (range, 37.1-221 hours). Nine patients were successfully weaned from ECMO. The in-hospital mortality rate was 91.1% (21 of 23). There were complications in 3 patients (cannulation site bleeding, limb ischemia, and gastrointestinal bleeding). Conclusion ECMO is a useful treatment for patients with circulatory and/or pulmonary failure. However, in patients with HM, the outcomes of ECMO treatment results were very poor, so it is advisable to carefully decide whether to apply ECMO to these patients.

H2 is regarded as an alternative to current energy carriers without CO2 emission. To supplement traditional H2 production by fossil fuels, alkaline water electrolysis (AWE) is back in the spotlight. Unfortunately, H2 production by AWE is not economically practical yet compared with current fossil fuel H2 production methods. In this context, scenario analysis was performed in this study to find a suitable and reasonable scenario in which AWE is cost-competitive in terms of the levelized cost of H2 (LCOH) on the basis of diverse economic parameters such as the unit electricity price, the learning curve, and the automation level. From scenario analysis results, it is identified that the unit electricity price is the most effective economic factor to determine the LCOH followed by the learning curve and the automation level demonstrating that the introduction of surplus electricity, inevitably generated from renewable sources, can be very crucial for H2 production from AWE to be economically viable compared with the estimated LCOH of 1.25 USD per kg H2 in 2030 targeted by the United States Department of Energy. Most importantly, it can provide technical and economic guidelines on the basis of scenario analysis results. This can be very useful for decision makers to make economic and environmental policies in Korea and will result in entering the H2 economy society in the near future.

Ethylenethiourea (ETU) is one of the main metabolite of ethylenebisdithiocarbamate fungicides and potential exposure is highest for workers involved in rubber and fungicide production. Exposure of ETU induces endocrine disruption, teratogenesis, carcinogenicity, and goitrogenicity. ETU was administrated at concentration of 2 mg/kg/day for 58 weeks in C57BL/6 mice. After 58 weeks, blood samples were analyzed serum lipid profile, hepatic function dices, and plasma levels of creatine and blood urea nitrogen. Isolated kidneys were stained with haematoxylin-eosin. Analysis of miRNA expression profile was conducted on Affymetrix miRNA 4.0 Array. Chronic diet of ETU induced body weight loss, increased serum triglyceride and total cholesterol, increased plasma creatine and blood urea nitrogen, injured glomerulus and nephron tubule, induced severe hydronephrosis and polycystic kidney. ETU diet increased expression levels of the biomarker of renal injury and fibrosis in kidney. miR-17~92 cluster and miR-182-5p associated with cyst progression were increased in expression levels on the kidney. Chronic exposure to ETU at low concentrations results in functional and structural damage to the kidney, and increases cyst formation in the kidney.

Background The aim of this study was to evaluate the outcomes of surgical resection in patients with radiographically noninvasive lung adenocarcinoma according to the surgical strategy. Methods A retrospective study was conducted of 128 patients who underwent pulmonary resection for ground-glass opacity (GGO)-dominant nodules measuring ≤2 cm with a consolidation/tumor ratio ≤0.25 based on computed tomography between 2008 and 2015. The 5-year disease-free survival (DFS) rate and 5-year overall survival (OS) rate were analyzed. Results Among the 128 patients, wedge resection, segmentectomy, and lobectomy were performed in 40 (31.2%), 22 (17.2%), and 66 patients (51.6%), respectively. No significant differences were found among the groups in the mean size of tumors (p=0.119), the rate of pure-GGO nodules (p=0.814), the consolidation/tumor ratio (p=0.695), or the rate of invasive adenocarcinoma (p=0.378). Centrally located tumors were more common in the lobectomy group (21.2%) than in the wedge resection (0%) or segmentectomy (0%) groups (p=0.001). There were no significant differences in the 5-year DFS rate (100%, 100%, 92.7%, respectively; p=0.76) or 5-year OS rate (100%, 100%, 100%; p=0.223) among the wedge resection, segmentectomy, and lobectomy groups. Conclusion For radiographically noninvasive lung adenocarcinoma measuring ≤2 cm with a consolidation/tumor ratio ≤0.25, wedge resection and segmentectomy could be comparable surgical options to lobectomy.

A 61-year-old woman who presented with claudication and dyspnea on exertion was found to have severe calcified narrowing of the descending aorta and severe insufficiency of the aortic valve. These findings were compatible with Takayasu arteritis. To treat these hemodynamic abnormalities, extra-aortic bypass surgery combined with replacement of the aortic valve and ascending aorta-to-hemiarch replacement was performed through a separated upper hemi-sternotomy and limited median laparotomy. We present our successful surgical experience with this case.

Lee, J.L.; Kim, J.W.; Kim, H.S.; Cho, W.C., and Lee, J., 2018. Development of prediction system for invasion of swell-like waves on the southern coast of Korea. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 706–710. Coconut Creek (Florida), ISSN 0749-0208.Recently, several drowning accidents caused by rip currents were reported along Haeundae Beach, located at the southeastern corner of the Korean Peninsula. Several dozen people were swept away by rip currents, and subsequently rescued between August 7 and 10, 2012. The main cause of rip currents is swell waves that approach the shore. The rip current becomes more dangerous when a relatively long-period swell-like wave invades and is intensified, during the passage of typhoons far off shore. However, existing wind wave models require significant computational cost and time to obtain solutions to a set of partial differential equations, and have low accuracy for predicting the invasion of swell-like waves on coasts because they simultaneously calculate wind wave generation and wave propagation. In this study, we used a fractional step method to solve the wind wave generation and swell wave propagation components, in which the former is simulated using a typical spectrum approach and the latter is simulated using a Lagrangian approach. The results from the theoretical model were compared with field data collected during the dangerous rip current events in August 2012.

Kim, H.J.; Cho, S.M., and Cho, W.C., 2018. Numerical analysis of beach erosion at Jeongdongjin Beach in South Korea using field survey and measurement data. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 596–600. Coconut Creek (Florida), ISSN 0749-0208. Recently, Jeongdongjin Beach in Gangneung, Gangwon–do, in the eastern part of South Korea, has been seriously eroded, and several parts of the revetments along the coast were subsided due to frequent high wave attacks. Thus, several parts of the Jeongdongjin rail bike track and facility in the southern part of Jeongdongjin station were damaged and washed out. In this study, field surveys and measurements (including waves, current, water depth, seabed material, beach profile, and shoreline) at Jeongdongjin Beach 2014–2015 were conducted to analyze and determine the erosion process. From the surveys and...

The chemical looping strategy for hydrogen production (CLH2) offers a potentially viable option for efficient fuel conversion to hydrogen with the simultaneous capture of CO2. Typically, this process uses an iron-based composite as an oxygen carrier and syngas or methane as a fuel. The environmental and economic concerns motivate the use of abundant by-product iron oxide and the industrial off-gas for CLH2. Here we showed that H2 could be simply recovered from the industrial off-gas in a circulating fluidized bed with a mixture of the inexpensive raw material of by-product iron oxide and sand particle. The fluidization of the by-product iron oxide powder, which showed poor fluidization behavior, is improved by adding 60 vol% of sand particle. The industrial off-gas was completely converted to CO2 and H2O in a two-stage fluidized mode with a solid reactant of Fe2O3 of the binary particles, and then H2 was produced by oxidizing the reduced by-product iron oxide powder with steam. The binary particles showed consistent catalytic activity under multiple redox cycles by providing macropores with a size of ∼5 μm which facilitated gas diffusion. These findings provided valuable information for the future development of CLH2 based on by-products.

Alkaline water electrolysis (AWE) is a mature technology for producing hydrogen using variable renewable sources. AWE typically uses a concentrated electrolyte and a porous separator between the two electrodes to deliver ionic conductivity and to separate the released gases. The porous separator typically requires highly concentrated electrolytes (25~30 wt%) to provide high ionic conductivity. However, the circulation of the concentrated electrolyte in the electrolyzer block causes loss of Faraday efficiency and corrosion. Herein, we show that a cellulose nanocrystals (CNCs)-blended Zirconia/Polysulfone composite porous separator exhibits both low area resistance of 0.18 Ω cm2 and low hydrogen permeability of 4.7 × 10−12 mol bar−1 s−1 cm−1 at low electrolyte contents (10 wt% KOH solution). Meanwhile, a commercial Zirfon® separator exhibited poor performances of the high area resistance of 0.71 Ω cm2 and high hydrogen permeability of 305 × 10−12 mol bar−1 s−1 cm−1 under the same condition. The cell comprising the optimized composite separator displayed a remarkable capability of 1.83 V at 600 mA cm−2 with 10 wt% KOH solution for 300 h in a stable mode. Hydrophilic cellulose nanocrystals were successfully incorporated into the hydrophobic polymer network, resulting in lowering the area resistance and gas permeability of the separator. These results demonstrate that AWE equipped with (CNCs)-blended Zirconia/Polysulfone composite porous separators can achieve high performance using low concentration electrolytes, contributing to lifetime.

Alkaline water electrolysis has been in the spotlight for green H2 production using electricity generated from renewable energy because of its high technology readiness level and low investment. However, commercialization of alkaline water electrolysis is challenging because of the low current density. Therefore, a techno-economic and environmental assessment was conducted for green H2 production by alkaline water electrolysis with experimental data from the advanced alkaline water electrolysis system of the Korea Institute of Energy Research (KIER) to identify the potential of this technology. Based on techno-economic analysis results, the stack cost and unit electricity price must be below 0.035 $ kWh−1 and 406 $ kW−1, respectively, to make this technology cost-competitive compared to the conventional H2 production method (

The main challenge for the anode electrocatalyst in a polymer electrolyte membrane water electrolyzer (PEMWE) is to maintain activity and stability simultaneously under the corrosive environment. We report a highly active and durable iridium electrocatalyst supported on boron carbide for the oxygen evolution reaction. The physical and electrochemical properties of the catalyst are controlled by changing the synthetic reduction temperature from 30 °C to 100 °C. The prepared Ir/B4C-100 °C catalyst shows two times higher mass activity than Ir/B4C-30 °C, even outperforming two commercial catalysts. The improved activity can be correlated to the high concentration of Ir (III) and OH species on the surface and the well-dispersed iridium nanoparticles on the support. Controlling the reduction temperature is also found to enhance iridium stability by developing the interactions between iridium and B4C. These metal-support interactions inhibit the oxidative dissolution of Ir (III) and the aggregation of iridium species. Ir/B4C-100 °C also shows better single cell performance than those of two commercial catalysts when tested in a PEMWE. The cell with the synthesized catalyst of Ir/B4C-100 °C shows a current density of 1.98 A/cm2 at 1.8 V, whereas those with two commercial catalysts exhibit values of 1.36 and 0.692 A/cm2 at 1.8 V, respectively.

Synthetic natural gas (SNG) production from captured CO2 and H2 produced by water electrolysis using renewable energy is of increasing interest for low-carbon fuel production, CO2 utilization technology, and unstable renewable energy storage. In this study, the effect of voltage degradation in a water electrolyzer, a core technology for SNG production, on the unit production cost of SNG production and CO2 emissions, with different water electrolysis types such as alkaline electrolysis (AEL), proton exchange membrane electrolysis (PEMEL), and solid oxide electrolysis (SOEL), was identified through techno-economic and environmental assessment. In particular, the energy efficiency, unit production cost of SNG, and CO2 emissions were identified based on the change in the power consumption caused by voltage degradation. Moderate voltage loss results in a decrease in energy efficiency from 53.8% to 48.8% in AEL, 55.3% to 47.0% in PEMEL, and 76.3% to 51.2% in SOEL. Moreover, respective SNG unit production costs of 140.3–170.2 USD MWh−1, 157.5–203.1 USD MWh−1, and 153.1–353.5 USD MWh−1 for AEL, PEMEL, and SOEL, respectively, were obtained, showing an increase in SNG production cost due to the voltage degradation. Furthermore, total CO2 emissions for the SNG production process were investigated considering voltage degradation as well as electricity generation sources.