Various disposal methods for spent nuclear fuels (SNFs) are being researched, and one of these methods involves separating high heat-generating nuclear isotopes such as Strontium-90 (90Sr) and Cesium-137 (137Cs) for deep disposal. These isotopes has relatively short half-lives and substantial decay energies. Especially, 90Sr undergoes decay through Yttrium-90 to Zirconium-90, emitting intense heat with beta radiation. Therefore, the removal of these high heat-generating isotopes will significantly contribute to reducing disposal site area. To remove 90Sr from SNFs, molten salt was utilized in KAERI. During this process, it was discovered that 90Sr dissolves in the molten salt in the form of SrCl2 and/or Sr4OCl6. Afterwards, it is crucial to recover 90Sr in the form of oxide from the salt to create immobilized forms for disposal. This can be achieved by reactive distillation with K2CO3. However, the amount of 90Sr within the SNFs is only 0.121wt%, and even if all the 90Sr in the SNFs were to leach into the molten salt, the quantity of 90Sr in the molten slat would still be very small. Therefore, adding K2CO3 to the molten salt for reactive distillation could result in significant possibilities of side reactions occurring. In this study, a two-step process was employed to mitigate the side reactions: the 1st step involves evaporating the all molten salts and the 2nd step includes adding K2CO3 to make oxides through solid-solid reaction. Eutectic LiCl-KCl, which is the most commonly used salt, was employed. The eutectic LiCl-KCl with SrCl2 was heated at 850°C for 2 h to evaporate the salts under a vacuum (> 0.02 torr). However, after examining the distillation product before the solid-solid reaction, it was observed that SrCl2 reacted with KCl in the salt, resulting in the formation of KSr2Cl5. It means that salts containing KCl are not suitable candidates for reactive distillation aimed at producing immobilized forms. As an alternative, MgCl2 could be a highly promising candidate because it is inert to SrCl2 and according to a recent study in KAERI, MgCl2 exhibited the most efficient separation of Sr among various salts. Therefore, we plan to proceed with the two-step reactive distillation using MgCl2 for the future work.

Sulfur and nitrogen co-doped carbon dots (NSCDs) were quickly synthesized by the microwave-assisted method from triammonium citrate and thiourea. NSCDs showed a quantum yield of 11.5% with excitation and emission bands at 355 and 432 nm, respectively. Also, a fluorescence quenching was observed in the presence of Pb(II) ions, and the as-synthesized CDs were used as a sensitive probe for detecting Pb(II) in water and food samples. The results showed the optimal conditions for Pb(II) determination were CDs concentration of 0.02 mg mL− 1 at pH 6.0–7.0 and an incubation time of 20 min. The relative fluorescence intensity of NSCDs was proportional to Pb(II) concentrations in the range of 0.029–2.40 and 2.40–14.4 μmol L− 1 with a correlation coefficient (R2) of 0.998 and 0.955, respectively, and a detection limit of 9.2 × 10– 3 μmol L− 1. Responses were highly repeatable, with a standard deviation below 3.5%. The suggested method demonstrates the potential of a green, fast, and low-cost approach for Pb(II) determination in water, tea, and rice samples with satisfying results.

Nitrogen and phosphorous dual-doped carbon nanotubes (N,P/CNT) have been grown in a single-step direct synthesis process by CVD method using iron-loaded mesoporous SBA-15 support, as an electrode material for the energy storage device. For comparison, pristine nanotubes, nitrogen and phosphorous individually doped nanotubes were also prepared. The basic characterization studies clarify the formation of nanotubes and the elemental mapping tells about the presence of the dopant. Under three-electrode investigations, N,P/CNT produced a maximum specific capacitance of about 358.2 F/g at 0.5 A/g current density. The electrochemical performance of N,P/CNT was further extended by fabricating as a symmetric supercapacitor device, which delivers 108.6 F/g of specific capacitance for 0.5 A/g with 15 Wh/kg energy density and 250 W/kg power density. The observed energy efficiency of the device was 92.3%. The capacitance retention and coulombic efficiency were 96.2% and 90.6%, respectively, calculated over 5000 charge–discharge cycles.

A novel kind of self-assembled graphene quantum dots-Co3O4 (GQDs-Co3O4) nanocomposite was successfully manufactured through a hydrothermal approach and used as an extremely effectual oxygen evolution reaction (OER) electrocatalyst. The characterization of morphology with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that Co3O4 nanosheets combined with graphene quantum dots (GQDs) had a new type of hexagonal lamellar selfassembly structure. The GQDs-Co3O4 electrocatalyst showed enhanced electrochemical catalytic properties in an alkaline solution. The start potential of the OER was 0.543 V (vs SCE) in 1 M KOH solution, and 0.577 V (vs SCE) in 0.1 M KOH solution correspondingly. The current density of 10 mA cm− 2 had been attained at the overpotential of 321 mV in 1 M KOH solution and 450 mV in 0.1 M KOH solution. Furthermore, the current density can reach 171 mA cm− 2 in 1 M KOH solution and 21.4 mA cm− 2 in 0.1 M KOH solution at 0.8 V. Moreover, the GQDs-Co3O4 nanocomposite also maintained an ideal constancy in an alkaline solution with only a small deterioration of the activity (7%) compared with the original value after repeating potential cycling for 1000 cycles.

This study was aimed to determine the changes in CO2 concentration according to the temperatures of daytime and nighttime in the CO2 supplemental greenhouse, and to compare calculated supplementary CO2 concentration during winter and spring cultivation seasons. CO2 concentrations in experimental greenhouses were analyzed by selecting representative days with different average temperatures due to differences in integrated solar radiation at the growth stage of leaf area index (LAI) 2.0 during the winter season of 2022 and 2023 years. The CO2 concentration was 459, 299, 275, and 239 μmol·mol-1, respectively at 1, 2, 3, and 4 p.m. after the CO2 supplementary time (10:00-13:00) under the higher temperature (HT, > 18°C daytime temp. avg. 31.7, 26.8, 23.8, and 22.4°C, respectively), while it was 500, 368, 366, 364 μmol·mol-1, respectively under the lower temperature (LT, < 18°C daytime temp. avg. 22.0, 18.9, 15.0, and 13.7°C, respectively), indicating the CO2 reduction was significantly higher in the HT than that of LT. During the nighttime, the concentration of CO2 gradually increased from 6 p.m. (346 μmol·mol-1) to 3 a.m. (454 μmol·mol-1) in the HT with a rate of 11 μmol·mol-1 per hour (240 tomatoes, leaf area 330m2), while the increase was very lesser under the LT. During the spring season, the CO2 concentration measured just before the start of CO2 fertilization (7:30 a.m.) in the CO2 enrichment greenhouse was 3-4 times higher in the HT (>15°C nighttime temperature avg.) than that of LT (< 15°C nighttime temperature avg.), and the calculated amount of CO2 fertilization on the day was also lower in HT. All the integrated results indicate that CO2 concentrations during the nighttime varies depending on the temperature, and the increased CO2 is a major source of CO2 for photosynthesis after sunrise, and it is necessary to develop a model formula for CO2 supplement considering the nighttime CO2 concentration.

Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20°C temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 μmol m-2 s-1. The kale plants were then transferred to two chambers with different CO2 concentrations (382±3.2 and 1,027±11.7 μmol mol-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO2 were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO2 environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO2 environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

This study was conducted to investigate the growth characteristics of cucumber (Cucumis sativus L. ‘Joeunbaekdadagi’) and tomato (Solanum lycopersicum L. ‘Dotaerang Dia’) seedlings by light intensities and CO2 concentrations in a closed-type plant production system (CPPS). Cucumber and tomato seeds were sown in 50-cell trays and germinated in CPPS at air temperature 25 ± 1°C and relative humidity 50 ± 10% for 4 days. After germination, the CO2 concentrations and light intensity treatment were treated at 500 (ambient), 1,000, and 1,500 μmol·mol-1 and 100, 200, and 300 μmol·m-2·s-1 photosynthetic photon flux density (PPFD), respectively. The leaf area of cucumber showed the highest value in CO2 1,500 μmol·mol-1. However, the leaf area of the tomato had no significant difference in CO2 concentrations and light intensities treatments. In cucumber and tomato both seedlings, the growth and quality such as compactness and leaf area rate were increased with the increase of light intensity, and there were highest in 300 μmol·m-2·s-1. The root surface and number of root tips of cucumber and tomato seedlings were significantly increased with the increase in light intensity. In conclusion, the regulation of the CO2 concentrations and light intensity can control the growth and quality of cucumber and tomato seedlings in CPPS, especially, increasing the light intensity can improve more significantly the growth and quality of seedlings.

인터넷 시대를 맞아 온라인 콘텐츠 플랫폼은 텔레비전 미디어 시대의 송년 매체 의식을 변화시켰고, 기수 매체의 변화 중의 의식 활동을 분석 하여 새로운 환경을 제공하였다.　따라서 본 연구에서는 온라인 콘텐츠 플랫폼에서 개최하는 송년회를 분석 대상으로 선정하여 온라인 커뮤니티 의 의식 활동을 연구하였다. 이론적인 측면으로 본 연구는 매체 의식의 이론적 관점에서 참여형 문화 이론과 결합하여 커뮤니티의 매체 의식 실 천을 분석하고, 참여형 매체 의식을 사용하여 온라인 콘텐츠 플랫폼에서 커뮤니티의 역할에 응한다. 본 연구는 콘텐츠의 협력 공동창작 및 커뮤 니티 사용자 참여 등 두 가지 관점에서 온라인 커뮤니티의 송년 행사와 다른 미디어 플랫폼이 창출하고 주도하는 송년 행사의 차이점을 분석한 다. 본 연구의 핵심 목적은 온라인 콘텐츠 플랫폼의 송년 활동의 혁신을 분석하고, 온라인 커뮤니티가 매체 의식 활동을 만들고 기획하는 방법을 더 잘 이해하고, 대중문화와 커뮤니티 사용자가 콘텐츠 공동창출을 통해 커뮤니티의 단결을 만들고 커뮤니티의 응집 효과를 강화하며 상호 작용 에 참여하여 의식 상호 작용을 촉진할 수 있는 아이디어를 제공하는 것 이다.　본 연구에서는 콘텐츠 창작 과정에서 온라인 콘텐츠 플랫폼에서 커뮤니티 네트워크의 주도적 위치를 지적했다. 따라서 콘텐츠 서사 단계 에서는 시청자에게 주의를 기울이고 매체 전반에 걸쳐 참여감을 부여하 고 플랫폼은 미디어 의식의 장이자 중개자가 된다.

Recently, the market competition has been fiercer due to the acceleration of technological change and the launch of intelligent products. In this situation, technology cooperation activities through networks rather than independent technological innovation activities of a single company or institution are recognized as a crucial strategy to gain competitiveness. Technology cooperation can take various forms depending on the target technology, and researchers have conducted performance analyses of technology cooperation types. However, there have not been data-based quantitative studies on the types and trends of technology cooperation for the target technology. In this paper, we explored the difference between the technology cooperation types by technology and time using the formal concept analysis method and co-patent information. In particular, the proposed methodology has been verified through the case study of electric vehicles, and it is intended to suggest the direction of technological cooperation according to specific technologies and cooperation targets in the future

본 연구는 대학원생의 혁신행동에 영향을 미칠 수 있는 인지적 유연성, 디지털 리터러시 및 협력 적 조절 간의 구조적 관계를 구명하고자 하였다. 특히, 대학원생의 인지적 유연성이 혁신행동에 영 향을 미치는 과정에서 디지털 리터러시와 협력적 조절이 매개변인으로 작용하는지 살펴보는 데 중 점을 두었다. 이를 위해 서울 소재 S 국립대학 소속 대학원생(N= 1,062)을 대상으로 한 설문조사 응답을 분석 자료로 사용하였으며, 변인 간 관계를 검증하기 위해 구조방정식 모형을 활용하였다. 주요 연구 결과는 다음과 같다. 첫째, 인지적 유연성은 혁신행동에 직접적인 정적 영향을 미치는 것 으로 나타났다. 둘째, 두 매개변인 디지털 리터러시와 협력적 조절 모두 대학원생의 혁신행동에 각 각 정적인 직접 효과를 가지는 것으로 확인하였다. 셋째, 대학원생의 인지적 유연성과 혁신행동 간 의 관계에서 디지털 리터러시와 협력적 조절의 개별 매개효과는 통계적으로 유의했으며, 두 변인의 이중매개효과 역시 유의한 것으로 나타났다. 본 연구는 기업 환경에서 주로 연구되어 왔던 인지적 유연성과 혁신행동 간의 관계를 대학원 교육의 맥락으로 확장하여 탐구하였다는 데에 그 의의가 크 다. 또한, 대학원생의 혁신행동에 영향을 미칠 수 있는 행동적, 사회적 변인을 고려하였다는 점에서 중요한 시사점을 가진다. 본 연구를 통해 대학원생의 혁신행동 제고를 통한 새로운 지식 창출과 국 가경쟁력 강화를 위해 대학원 차원에서의 실천적 노력이 필요함을 제언하였다.

한국의 목조건축문화유산은 상당수가 산림에 인접하여 흰개미에 의한 피해에 취약하다. 국내 흰개미 방제법은 살충제 접촉을 통한 화학적 방제법이 주로 이용되며, 방제 기간을 단축하기 위해서는 흰개미를 빠르게 약제까지 유인시킬 방법이 필요하다. 본 연구에서는 한국 서식 흰개미 에 대한 유인물질로 이산화탄소를 선정하여 유인여부 및 적절한 유인농도를 탐색하였으며, 지중 환경에서의 유인효력 기초평가를 진행하였다. 평가를 통해 흰개미에 대한 이산화탄소의 유인 효과를 확인하였으며, 이산화탄소 농도 10% 이하의 유효한 범위를 선정하였다. 또한 지중에서의 유인 효과를 확인함으로써 지중 환경에서의 적용 가능성을 파악하였다. 향후 현장에서 이산화탄소의 적용방안을 연구함으로써, 목조건축문화유 산의 흰개미 방제 시 개선된 방제 효과를 가질 수 있을 것으로 사료된다.

The disposal of organic pollutants is one of the important research topics. Some of the studies in this field are based on the degradation of organic pollutants with a catalytic agent. The cobalt tetraoxide/peroxymonosulfate system is an important catalytic system used for the radical degradation of organic pollutants. To increase the catalytic efficiency of such reactions, graphitization of activated carbon used as a support solid and nitrogen doping to the carbon structure are commonly used methods. In this study, cobalt tetraoxide production, N-doping and graphitization were carried out in a single step by heat treatment of activated carbon doped with the phthlocyanine cobalt (II) complex. The catalytic performance of the catalyst/ peroxymonosulfate system was investigated by changing the pH, catalyst, and PMS concentration parameters on rhodamine B and 1,3,5 trichlorophenol, which were used as models. It was seen that the catalysts had 97% activity on rhodamine B in 16 min and 100% on 1,3,5 trichlorophenol in 6 min. It was observed that the catalysts continued to show high catalytic activity for five cycles in reusability studies and had a very low cobalt leaching rate. These results are in good agreement with previously published studies. In line with these results, the synthesized N-doped graphitic carbon/Co3O4 catalyst can be used as an effective catalyst for wastewater treatments.

Photocatalytic CO2 reduction is a promising approach for reducing CO2 emissions and achieving the goal of carbon neutrality. In this work, selectively coupling Cu(OH)2 and CuO with amine-modified brookite TiO2 ( NH2–B–TiO2) has been achieved by a simple precipitation method. The results show that CuO is better than Cu(OH)2 as a co-catalyst to enhance the CO2 photoreduction capability of NH2– B–TiO2. The highest rates of CO2 conversion to CH4 and CO of NH2– B–TiO2–CuO composite reach 6.05 and 3.25 μmol h− 1 g− 1, respectively, which is higher than 8 times the yield of CH4 of NH2– B–TiO2. It is proposed that the NH2– B–TiO2–CuO composite offers an effective charge transfer through the formation of a p–n junction between NH2– B–TiO2 and CuO interfaces, while in the NH2– B–TiO2–Cu(OH)2 composite, the Cu(OH)2 dominantly serves as an electron sink to capture photo-induced electrons, promoting photo-induced carrier separation. This work provides an ingenious synthetic method for selectively anchoring Cu(OH)2 and CuO on semiconductors with different charge transfer routes for an efficient CO2 photoreduction.

Amorphous molybdenum sulfide ( MoSx) has been regarded as a promising hydrogen evolution reaction (HER) catalyst due to its mild preparation conditions and low-cost precursor materials. In this work, we report a simple strategy combining the growth of amorphous MoSx on the surface of metal organic frameworks (ZIF-67) and annealing treatment to prepare Co-doped MoSx nanopolyhedrons (denoted as CoMoSx NPs). The CoMoSx NPs exhibit excellent HER activity in acid condition with an overpotential of 188 mV at a current density of 10 mA cm− 2 (η10), and a relatively stable overpotential after 2000 cyclic voltammetry (CV) cycles testing. The excellent HER performance of the CoMoSx NPs can be attributed to the doping of Co element adjust the electronic structure and increase the conductivity of catalyst, and the nanopolyhedrons structure which can expose more active sites for HER electrocatalytic. This study offers a low-cost and simple strategy to prepare high-activity HER catalyst, which holds great promises in developing advanced electrocatalysts for energy storage.

The synthesis of a novel first stage GIC containing simultaneously lithium, potassium and barium through a solid–liquid reaction by molten salts method is described. Such a route has been largely developed in our laboratory for intercalation of metals into graphite. The interplanar distance of this quaternary compound reaches 950 pm and exhibits poly-layered intercalated sheets defined by X-ray measurements. The Li0.2K0.75Ba0.6C6 chemical formula of the compound is determined by ion beam analysis and this GIC is remarkably homogeneous. This GIC is the first poly-layered one containing barium.

이 연구는 팬데믹(pandemic) 전후 국제항공여객 운송시장을 대상으로 항공편 운항에 의한 CO2 배출 특성과 변화를 체계적으 로 파악하는 것을 주요 목적으로 한다. 이를 위해 2019년과 2021년 2분기 전 세계 국제여객 항공편 스케줄 데이터를 기반으로 ICAO(International Civil Aviation Organization)의 CERT(CO2 Estimation and Reporting Tool) 인벤토리를 이용하여 노선 단위의 CO2 배출량을 추정한 후, 노선의 대권 거리와 항공기의 크기를 기준으로 구분된 하부시장에 따른 CO2 배출량과 배출 효율성의 분포와 변화를 비교분석하였다. 주요 분석 결과는 다음과 같다. 첫째, 2021년 2분기 전 세계 국제항공여객 운송시장의 CO2 배출량은 약 31.6백만 톤으로 추정되었으며. 2019년 동 분기(117.95백만 톤) 대비 약 73.21% 감소하였다. 두 시기 모두 5,000km 이상의 장거리 시장, 그리고 100~400석 항공기 운용 시장에서의 배출량 비중이 높게 나타났다. 다만 팬데믹 기간에는 5,000km 이상, 그리고 400석 이상 항공기 시장에서 CO2 배출량의 감소가 두드러지게 나타났다. 둘째, 2021년 2분기 시장의 CO2 배출 효율성은 2019년 동 분기 대비 약 4% 향상되었다. 두 시기 모두 노선의 대권 거리와 항공기의 크기가 증가할수록 배출 효율성이 감소하는 경향이 존재하였으며, 팬데믹 기간 중 일부 하부시장에서는 구형 및 초대형 기종들의 운항 감축(혹은 중단)이 두드러짐에 따라 배출 효율성이 향상되기도 하였다. 마지막으로 팬데믹 전후 주요 국제노선들의 CO2 배출 효율성 변화를 탐색한 결과, 글로벌 허브 공항들을 연결하는 대륙 간 장거리 노선들을 중심으로 효율성이 낮게 나타난 반면, 차상위 계층 공항들과 연결된 일부 노선들, 그리고 동남아･동북아의 주요 공항들을 연결하는 역내 노선들은 상대적으로 효율성이 높게 나타났다. 본 연구는 팬데믹 전후 전 세계 국제항공여객 운송시장의 운영 실적과 CO2 배출에 대한 세부 특성과 변화를 실증적으로 분석했다는 점에서 의의가 있다.