In order to predict the process window of laser powder bed fusion (LPBF) for printing metallic components, the calculation of volumetric energy density (VED) has been widely calculated for controlling process parameters. However, because it is assumed that the process parameters contribute equally to heat input, the VED still has limitation for predicting the process window of LPBF-processed materials. In this study, an explainable machine learning (xML) approach was adopted to predict and understand the contribution of each process parameter to defect evolution in Ti alloys in the LPBF process. Various ML models were trained, and the Shapley additive explanation method was adopted to quantify the importance of each process parameter. This study can offer effective guidelines for fine-tuning process parameters to fabricate high-quality products using LPBF.

2003년 국내에 침입한 외래종 등검은말벌(Vespa velutina nigrithorax)은 현재 남한 전체에 확산된 상태이며 이들로 인한 사회 경제적 피해는 지속적으로 증가하고 있다. 따라서 이들을 방제하기 위한 다양한 방법이 시도되 고 있으나 그 효과는 대부분 미미한 상황이다. 그러나 최근 생물학적 방제에 대한 관심이 집중되는 상황에서 외래종 등검은말벌에 대한 새로운 포식자 2종이 발견되어 이를 보고하고자 한다. 2023년 8월 11일 전북 무주군 적상면 일대에서 오소리 배설물 조사 중 배설물 속에 다량의 말벌 사체가 발견되었고 분석 결과 10여개체의 등검 은말벌로 나타났다. 이는 일반적으로 땅벌류를 주로 포식하는 오소리가 대형 말벌류를 포식하는 첫 기록이다. 또한 2023년 12월 10일 안동 일대에서 등검은말벌 벌집 조사를 하던 중 벌집에 10여 마리의 직박구리가 벌집 외피를 깨고 내부에 있는 애벌레와 성충들을 포식하는 장면이 관찰되면서 벌매에 이어 새로운 조류 포식자를 기록한다.

2023년 경상북도 상주시 떫은감 과수원에서 잎 표피아래 굴을 파고 들어가면서 원형 또는 부정형의 식흔자국 을 남기는 증상을 관찰하였다. 해충의 유충은 녹색에서 적색으로 변하며 번데기 단계를 거쳐 성충(길이 3㎜, 갈색) 이 되어 탈출하였다. 본 해충에 대해 잎에서의 피해증상과 실험실에서 유전분석 결과 Genbank(GU816671,486bp DNA liner, 2016)에 등재되어 있는 감잎가는나방(Cuphodes diospyrosella)으로 동정되었다. 일본에서 1957년 최초 보고 후 우리나라에서는 주로 경남 창원과 진주의 농약 무살포 및 유기농 단감원에서 발생하였으나, 이번 경북지 역에 처음 발견되어 떫은감 재배 농업인과 현장지도원의 감잎가는나방에 대한 피해증상 진단에 활용할 수 있을 것으로 생각된다.

The mobility of radionuclides in the subsurface environment is governed by a interaction of radioactivity characteristics and geochemical conditions with adsorption reactions playing a critical role. This study investigates the characteristics and mechanisms of radionuclides adsorption on site media in viewpoint of nuclear safety, particularly focusing on the potential effect of seawater infiltration in coastal site near nuclear power plant. Seawater intrusion alters the chemistry in groundwater, including parameters such as pH, redox potential, and ionic strength, thereby affecting the behavior of radionuclides. To assess the safety of site near nuclear power plant and the environmental implications of nuclide leakage, this research conducted various experiments to evaluate the behavior of radionuclides in the subsurface environment. High distribution coefficients (50-2,500 ml/g) were observed at 10 mg/L Co, with montmorillonite > hydrobiotite > illite > kaolinite. It decreased with competing cations (Ca2+) and was found to decrease significantly by 90% with a decrease in pH to 4. It is believed that the adsorption capacity of cationic radionuclides decreases significantly as the clay mineral surface becomes less negatively charged. For Cs, the distribution coefficient (180-560 ml/g) was higher for montmorillonite > hydrobiotite > illite > kaolinite. Compared to Co, it was found to be less influenced by pH and more influenced by competing cations. For Sr, the distribution coefficient (100-380 ml/g) was higher in the order of hydrobiotite > montmorillonite > illite > kaolinite. Compared to Cs, it was found to be less affected by pH and also less affected by the effect of competing cations compared to Cs. Seawater samples from Gampo and Uljin site near Nuclear Power Plant in Korea were analyzed to determine their chemical composition, which was subsequently used in adsorption experiments. Additionally, the seawater-infiltrated groundwater was synthesized in laboratory according to previous literature. The study focused on the adsorption and behavior of three key radionuclides such as cesium, strontium, and cobalt onto four low permeability media (clay minerals) such as kaolinite, illite, hydrobiotite, and montmorillonite known for their high adsorption capacity at a site of nuclear power plant. At concentrations of 5 and 10 mg/L, the adsorption coefficients followed the order of cobalt > cesium > strontium for each radionuclide. Notably, the distribution coefficient (Kd) values exhibited higher values in seawater-infiltrated groundwater environments compared to seawater with relatively high ionic strength. Cobalt exhibited a substantial adsorption coefficient, with a marked decrease in Kd values in seawater conditions due to elevated ionic strength. In contrast, cesium displayed less dependency on seawater compared to other radionuclides, suggesting distinct adsorption mechanisms, possibly involving fractured edge sites (FES) in clay. Strontium exhibited a significant reduction in adsorption in seawater compared to groundwater in all Kd sorption experiments. The adsorption data of cobalt, cesium, and strontium on clay minerals in contact with seawater and seawater-infiltrated solutions offer valuable insights for assessing radioactive contamination of groundwater beneath coastal site near nuclear power plant sites. This research provides a foundation for enhancing the safety assessment protocols of nuclear power plant sites, considering the potential effects of seawater infiltration on radionuclide behavior in the subsurface environment.

대벌레(Ramulus mikado)는 1990년 이후부터 2000년대 초반까지 경북을 중심으로 대발생을 하였던 돌발 해충 으로 2020~2023년에 수도권에서 대발생 사례가 다수 보고 되었다. 대벌레의 대발생 원인으로 기후변화가 지목되 고 있지만, 대벌레 개체군과 생물적·비생물적 환경 조건과의 관계를 이해하기 위한 연구는 매우 부족한 실정이 다. 본 연구에서는 주요 기주식물과 대벌레 발생 양상에 대한 관계를 이해하고자 수행하였다. 2022년부터 2023년 까지 대벌레 대발생 지역 중 하나인 청계산 일대 등산로를 따라 조사구를 선정한 뒤 주요 기주식물이자 우점종인 신갈나무, 아까시나무, 잔털벚나무를 대상으로 대벌레의 발생 밀도를 조사하였다. 그 결과, 조사지점 간의 대벌 레 평균 밀도는 유의한 차이가 발견되지 않았지만, 기주식물에 따른 밀도의 차이는 뚜렷하게 나타났다.

When damaged nuclear fuel is stripped and re-fabricated into stabilized pellets, it is necessary to analyze the characteristics of the stabilized pellets, such as density, leaching behavior, and compressive strength, for final disposal. In this study, simulated nuclear fuel with UO2 and burn-up of 35 GWd/tU and 55 GWd/tU was used to measure the compressive strength of the stabilization pellet. In order to change the density of the sintered pellet, a sintered pellet was prepared by heat treatment at 1,550°C and 1,700°C for 6 hours in a reducing atmosphere of 4% H2/Ar. In the case of UO2, the density was 10.4 g/cm3 (94.5% of T.D.) and 10.6 g/cm3 (96.6% of T.D.) depending on the sintering temperature (1,550°C, 1,700°C). In the case of simulated fuel with a burn-up of 35 GWd/tU, the density was 8.8 g/cm3 (80.9% of T.D.) and 10.2 g/cm3 (93.6% of T.D.) depending on the sintering temperature (1,550°C, 1,700°C). In the case of simulated fuel with a burn-up of 55 GWd/tU, the density was 8.3 g/cm3 (77.0% of T.D.) and 10.0 g/cm3 (92.3% of T.D.) depending on the sintering temperature (1,550°C, 1,700°C). It was found that the compressive strength of simulated nuclear fuel decreased with increasing burn-up and increased with increasing density. In the case of UO2, the compressive strengths were 717.8 MPa and 897.4 MPa when the densities were 10.4 g/cm3 and 10.6 g.cm3, respectively. In the case of simulated nuclear fuel with a burn-up of 35 GWd/tU, the compressive strengths were 472.1 MPa and 732.3 MPa when the densities were 8.8 g/cm3 and 10.2 g/cm3. In the case of simulated nuclear fuel with a burn-up of 55 GWd/tU, the compressive strengths were 301.4 MPa and 515.5 MPa when the densities were 8.3 g/cm3 and 10.0 g/cm3, respectively.

To investigate the effect of the catalyst and metal–support interaction on the methane decomposition behavior and physical properties of the produced carbon, catalytic decomposition of methane (CDM) was studied using Ni/SiO2 catalysts with different metal–support interactions (synthesized based on the presence or absence of urea). During catalyst synthesis, the addition of urea led to uniform and stable precipitation of the Ni metal precursor on the SiO2 support to produce Ni-phyllosilicates that enhanced the metal–support interaction. The resulting catalyst upon reduction showed the formation of uniform Ni0 particles (< 10 nm) that were smaller than those of a catalyst prepared using a conventional impregnation method (~ 80 nm). The growth mechanisms of methane-decomposition-derived carbon nanotubes was base growth or tip growth according to the metal–support interaction of the catalysts synthesized with and without urea, respectively. As a result, the catalyst with Ni-phyllosilicates resulting from the addition of urea induced highly dispersed and strongly interacting Ni0 active sites and produced carbon nanotubes with a small and uniform diameter via the base-growth mechanism. Considering the results, such a Ni-phyllosilicate-based catalyst are expected to be suitable for industrial base grown carbon nanotube production and application since as-synthesized carbon nanotubes can be easily harvested and the catalyst can be regenerated without being consumed during carbon nanotube extraction process.

The effect of Li2O addition on precipitation behavior of uranium in LiCl-KCl-UCl3 has been investigated in this study. 99.99% LiCl-KCl eutectic salt is mixed with 10wt% UCl3 chips at 550°C in the Pyrex tube in argon atmosphere glove box, with 10 ppm O2 and 1 ppm H2O. Then, Li2O chunks are added in mixed LiCl-KCl-UCl3 and the system has been cooled down to room temperature for 10 hours to form enough UO2 particles in the salt. The solid salt has been taken out from the glove box, and cut into three sections (top, middle and bottom) by low-speed saw for further microscopic analysis. Three pieces of solid salt are dissolved in deionized water at room temperature and the solution is filtered by a filter paper to collect non-dissolved particles. The filter paper with particles is baked in vacuum oven at 120°C for 6 hours to evaporate remaining moisture from the filter paper. Further analysis was performed for the powder remaining on the filter paper, and periphery of the powder (cake) on the filter paper. Scanning electron microscopy (SEM), electron diffraction spectroscopy (EDS), and X-ray powder diffraction (XRD) are adopted to analysis the characteristic of the particles. From SEM analysis, the powders are consisted of small particles which have 5 to 10 m diameter, and EDS analysis shows they are likely UO2 with 23 at. % of uranium and 77 at. % oxygen. Cake is also analyzed by SEM and EDS, and needle like structures are widely observed on the particle. The length of needle is distributed from 5 to 20 m, and it has 6 to 10 at. % of chlorine, which are not fully dissolved into deionized water at room temperature. From XRD analysis, the particles show the peak position of UO2, and the result is well matched with the SEM-EDS results. We are planning to add more Li2O in the system for fully reacting uranium in UCl3, and compare the results to find the effect of Li2O concentration on UO2 precipitation.

Solid state grain growth (SSCG) is a method of growing large single crystals from seed single crystals by abnormal grain growth in a small-grained matrix. During grain growth, pores are often trapped in the matrix and remain in single crystals. Aerosol deposition (AD) is a method of manufacturing films with almost full density from nano grains by causing high energy collision between substrates and ceramic powders. AD and SSCG are used to grow single crystals with few pores. BaTiO3 films are coated on (100) SrTiO3 seeds by AD. To generate grain growth, BaTiO3 films are heated to 1,300 oC and held for 10 h, and entire films are grown as single crystals. The condition of grain growth driving force is ΔGmax < ΔGc ≤ ΔGseed. On the other hand, the condition of grain growth driving force in BaTiO3 AD films heat-treated at 1,100 and 1,200 oC is ΔGc < ΔGmax, and single crystals are not grown.

시설토마토에서 사전에 해충밀도를 예찰 하지 않고 작물 정식과 동시에 적용한, 기생성/포식성 천적과 그들의 먹이원/서식처가 결합되어 있는, ‘Natural Enemy in First (NEF)’ 기술의 총채벌레와 진딧물 방제효과를 확인하였다. 처리 후 12주차에 NEF 처리구에서 총채벌레 밀도억제 효과는 천적처리구 및 관행방제구에 비해 각각 32%와 82% 더 높았다. 처리 후 진딧물의 밀도는 모든 처리구에서 낮게 유지되어 처리구간 유의성 있는 차이를 확인할 수 없었다.