본 연구는 교과서에서 엘니뇨 현상의 대기 순환과 관련하여 서술된 내용의 물리적 정합성 문제와 개념적 오류 를 분석하고, 현직 지구과학 교사들의 엘니뇨에 대한 이해 특성을 조사하였다. 이를 위해 2009 개정 교육과정과 2015 개정 교육과정의 고등학교 교과서 총 22종을 대상으로 엘니뇨 시기 열대 태평양의 기압, 무역풍, 워커 순환에 대한 설 명과 표현을 비교·분석하였다. 교과서 분석 결과, 일부 교과서에서 엘니뇨 시기의 기압 배치와 무역풍 형성 원리가 상 충되는 내용을 담고 있었으며, 무역풍이 서태평양 일부 해역에서 서풍 계열로 전환되는 관측 결과에도 불구하고 이를 열대 태평양 전역의 현상으로 서술하는 문제점이 발견되었다. 또한 워커 순환의 경우 교과서마다 상이한 형태로 제시되 면서도 이것이 실제 순환인지 편차를 나타내는 것인지에 대한 명확한 설명이 부족하였다. 현직 교사들을 대상으로 한 개념 조사에서는 평년값으로부터의 편차를 절대적 크기로 표현하거나 기압 배치와 무역풍의 물리적 관계성을 설명하는 데 있어 정합성이 부족한 특징이 나타났다. 특히 교사들이 제시한 워커 순환이 교과서의 서술 내용과 유사한 패턴을 보여, 교과서 내용의 제한점이 교사들의 이해에 영향을 주었을 가능성을 시사하였다.

Eu-doped SrAl2O4 is a promising thermoluminescent and mechanoluminescent material with high brightness and stability, making it suitable for various luminescent devices. In this study, SrAl2O4:Eu was synthesized using a solid-state reaction method, and the effects of reducing atmosphere and high-temperature synthesis conditions on its luminescence properties were systematically analyzed. The luminescence characteristics of SrAl2O4:Eu were found to be highly sensitive to synthesis temperature, atmosphere, and Eu doping concentration, and optimal conditions were determined. A comparison of SrAl2O4:Eu synthesized at 1,300 °C under air and reducing atmospheres revealed that the reducing atmosphere plays a critical role in stabilizing Eu2+ ions, forming a single-phase SrAl2O4, and establishing luminescence centers. Notably, SrAl2O4:Eu synthesized at 1,600 °C in a reducing atmosphere achieved a photoluminescence quantum yield (PLQY) of 43 % and a maximum luminance of 2,030 Cd/m2, showing significant improvement in luminescence efficiency compared to samples synthesized at 1,300 °C. When Eu doping concentrations were adjusted from 1 % to 20 %, the highest luminescence performance was observed at 10 % doping, while excessive doping (20 %) increased non-radiative recombination pathways, and no further improvement in luminescence efficiency was observed. X-ray Diffraction (XRD) and Photoluminescence (PL) analyses elucidated the effects of synthesis conditions on the structural stability and luminescence properties of SrAl2O4:Eu, and the optimal reducing atmosphere and high-temperature synthesis conditions are proposed. This study provides a synthesis strategy for enhancing the luminescence properties of Eu-doped SrAl2O4 and lays the groundwork for the development of highperformance thermoluminescent and mechanoluminescent materials.

The 2020 revision of Japan's Wholesale Market Act aimed to improve the financial performance of wholesale companies. Before the revision, the wholesale market saw a continuous decline in transaction volume and value, and the operating profit margin of wholesale companies was 0.18% in 2018, with 38.2% of wholesale companies experiencing operating losses. After the revision of the Wholesale Market Act, the operating profit margin of wholesale companies significantly improved to 0.41% by 2022. The reasons for this improvement are as follows: The transaction amount and the rate of change between 2022 and 2018 showed little difference. The number of markets increased by one central wholesale market, and while the number of buying and selling participants decreased, individual purchase volumes increased. The proportion of auctions further declined, and the number of direct transactions rose. As consignment collection decreased, purchased collection increased, leading to an improvement in financial performance. Ultimately, despite the short time frame, the revision of Japan's Wholesale Market Act led to positive changes that improved the financial performance of wholesale companies.

A digital twin (DT) is a virtual model designed to accurately reflect a physical object. We examine the economic benefits of digital aqua twin platform technology, which is applied to aquaculture to optimize production of cultured olive flounder and eel in South Korea. The economic benefits consist of two parts: (1) the benefits from technology development and (2) the benefits from technology adoption. The findings reveal that the benefits from technology development are greater than those from technology adoption. This implies that it is necessary to consider the former, which is often ignored in the previous literature, in quantifying the economic benefits of information technology.

온실 내부 환경은 지역에 따라 외부 환경의 영향을 지속적으로 받는다. 본 연구는 몽골, UAE(아부다비), 호 주(퀸슬란드) 등 지역별로 구축된 한국형 스마트 온실의 환경 특성을 비교하고자 수행하였다. 몽골과 아부다비의 온실 모두 내외부 엔탈피 차이가 감소함에 따라 환기율이 증가하였다. 아부다비의 반밀폐형 온실에서는 10시부터 14시까지 평균 내부 기온이 외부 기온보다 약 7－10°C 낮았고 내부 VPD(12mbar)는 외부 VPD(56mbar)보다 4.6 배 낮았는데 이 결과는 포그 시스템 운영과 관련이 있는 것으로 보인다. 퀸즐랜드 온실의 경우, 내부 온도가 외부 온 도보다 11시 기준 약 3.81°C 높았고, 내부 엔탈피와 VPD가 외부 온도보다 높았으며, 내부와 외부의 엔탈피 차이가 증가함에 따라 환기율이 증가하였다. 이 결과로 엔탈피를 낮추는 것은 환기와, VPD를 낮추는 것은 포그 시스템 작 동과 관련이 있는 것을 알 수 있다. 또한, 작물 생육에 적합한 환경 조건을 효과적으로 관리하기 위해 엔탈피와 VPD 기반의 포그, 환기 또는 난방 시스템이 필요하다는 것을 알 수 있다.

Ceramic materials have become essential due to their high durability, chemical stability, and excellent thermal stability in various advanced industries such as aerospace, automotive, and semiconductor. However, high-performance ceramic materials face limitations in commercialization due to the high cost of raw materials and complex manufacturing processes. Aluminum borate (Al₁₈B₄O₃₃) has emerged as a promising alternative due to its superior mechanical strength and thermal stability, despite its simple manufacturing process and low production cost. In this study, we propose a method for producing Al₁₈B₄O₃₃ spherical powder with increased uniformity and high flowability by controlling the particle size of B₂O₃. The content ratio of the manufactured Al18B4O33 spherical powder was Al2O3: B2O3 = 87:13, and it exhibited a 17% reduction in the Hausner ratio (1.04) and a 29% decrease in the angle of repose (23.9°) compared to pre-milling conditions, demonstrating excellent flowability.

Iron oxide (ε-Fe2O3) is emerging as a promising electromagnetic material due to its unique magnetic and electronic properties. This review focuses on the intrinsic properties of ε-Fe2O3, particularly its high coercivity, comparable to that of rare-earth magnets, which is attributed to its significant magnetic anisotropy. These properties render it highly suitable for applications in millimeter wave absorption and high-density magnetic storage media. Furthermore, its semiconducting behavior offers potential applications in photocatalytic hydrogen production. The review also explores various synthesis methods for fabricating ε-Fe2O3 as nanoparticles or thin films, emphasizing the optimization of purity and stability. By exploring and harnessing the properties of ε-Fe2O3, this study aims to contribute to the advancement of next-generation electromagnetic materials with potential applications in 6G wireless telecommunications, spintronics, high-density data storage, and energy technologies.

Chironomid larvae in drinking water treatment plants (DWTPs) and tap water lead to highlights the urgent need for effective control measures. The use of combined disinfectant treatments is becoming increasingly common to achieve optimal disinfection efficiency while minimizing residual contamination. This study was conducted to study the effect of combined treatment of disinfectants used in DWTPs on the biological control potential of chironomid larvae. In the experiment, Glytotendipes tokunagai larvae reared according to OECD guidelines were exposed to NaOCl, UV, and O3 complex substances, and biological responses were analyzed using survival rate and body color change as key indicators for 24 hours. The survival rate of larvae exposed to combined disinfectants mostly decreased in a time- and concentration-dependent manner, and lightening of body color was observed. The most significant decrease (53%) of the survival rate was observed to a combination of UV and 4 ppm NaOCl disinfectants and body color change also showed a statistically significant difference compared to the control group (P<0.001). The change in body color is suggested to be a physiological change caused by oxidation of hemoglobin due to exposure to disinfectant complexes. The results of this study contribute to determining the biological impact of combined disinfectant treatment on chironomid larvae of DWTPs, and can be used as data to suggest the biological control potential of disinfectants. In addition, it will provide important information for setting standards for combined disinfectant treatment to improve water quality in the future.

In this paper, we deal with the design of a model predictive control (MPC) for precise speed servo control of DC motor systems. The proposed controller is designed in the form of optimal control that calculates and outputs the optimized control input under constraints for each sampling. In particular, MPC designs the control inputs in advance for each sampling and predicts the outputs using them. Thus, it shows excellent control performance even in the case of disturbance or model uncertainty. The effectiveness of the proposed controller was demonstrated through computer simulations using MATLAB/Simulink and DC motor experimental system using real time controller. Moreover, the effectiveness of the proposed controller was confirmed by comparing its control performance with PID controller, which was tested under the same experimental condition as the MPC.

Electrical and thermal transport properties of a polycrystalline carrier-doped wide-gap semiconductor LaCu1-δ S0.5Se0.5O (δ = 0.01), in which the CuCh (Ch = S, Se) layer works as conducting layer, were measured at temperatures 473~673 K. The presence of δ = 0.01 copper defects dramatically reduces the electrical resistivity (ρ) to approximately one part per million compared to that of δ = 0 at room temperature. The polycrystalline δ = 0.01 sample exhibited ρ of 1.3 × 10-3 Ωm, thermal conductivity of 6.0 Wm-1 K-1, and Seebeck coefficient (S) of 87 μVK-1 at 673 K. The maximum value of the dimensionless figure of merit (ZT) of the δ = 0.01 sample was calculated to be 6.4 × 10-4 at T = 673 K. The ZT value is far smaller than a ZT ~ 0.01 measured for a nominal LaCuSeO sample. The smaller ZT is mainly due to the small S measured for LaCu1-δS0.5Se0.5O (δ = 0.01). According to the Debye model, above 300 K phonon thermal conductivity in a pure lattice is inversely proportional to T, while thermal conductivity of the δ = 0.01 sample increases with increasing T.

Hot section components of gas turbines are exposed to a high operating temperature environment. To protect these components, thermal barrier coatings (TBC) are applied to their surfaces. Yttria-stabilized zirconia (YSZ), which is widely used as a TBC material, faces limitations at temperatures above 1200 °C. To mitigate these issues, research has focused on adding lanthanide rare earth oxides and tetravalent oxides to prevent the phase-transformation of the monoclinic phase in zirconia. This study investigated the effects of varying TiO2 content in Nd2O3 and Yb2O3 co-doped YSZ composites. Increasing TiO2 content effectively suppressed formation of the monoclinic phase and increased the thermal degradation resistance compared to YSZ in environments over 1200 °C. These findings will aid in developing more thermally stable and efficient TBC materials for application in high-temperature environments.

Mo-ODS alloys have excellent mechanical properties, including an improved recrystallization temperature, greater strength due to dispersed oxides, and the ability to suppress grain growth at high temperatures. In ODS alloys, the dispersed Y2O3 and added Ti form Y-Ti-O complex oxides, producing finer particles than those in the initial Y2O3. The complex oxides increase high-temperature stability and improve the mechanical properties of the alloy. In particular, the use of TiH2 powder, which is more brittle than conventional Ti, can enable the distribution of finer oxides than is possible with conventional Ti powder during milling. Moreover, dehydrogenation leads to a more refined powder size in the reduction process. This study investigated the refinement of Yi2Ti2O7 in a nano Mo-ODS alloy using TiH2. The alloy compositions were determined to be Mo-0.5Ti-0.5Yi2O3 and Mo-1.0Ti-0.5Yi2Oi2. The nano Mo-ODS alloys were fabricated using Ti and TiH2 to explore the effects of adding different forms of Ti. The sintered specimens were analyzed through X-ray diffraction for phase analysis, and the microstructure of the alloys was analyzed using scanning electron microscopy and transmission electron microscopy. Vickers hardness tests were conducted to determine the effect of the form of Ti added on the mechanical properties, and it was found that using TiHi2 effectively improved the mechanical properties.

Hydrogen peroxide (H2O2) is widely used in bleaching treatments in the pulp and paper industry, in wastewater treatment, and as a food additive. However, H2O2 solutions are unstable and decompose slowly when subjected to external factors such as light, high temperatures, or metal compounds. Therefore, a simple and reliable method to measure the concentration of H2O2 is required for its proper use in various applications. We determined the concentration of an H2O2 solution by measurement at a single wavelength (249 nm) without any reagents or complex analytical procedures. In the present work, the measurable concentration of H2O2 was as low as 0.015 wt% (4.41 mM) and as high as 0.300 wt% (88.2 mM), with high linearity (99.99% at 249 nm) between the concentration of H2O2 and the optical density (OD) values. In addition, the method could be used to measure the concentration of H2O2 in a peracetic acid solution without interference from acetic acid and peracetate ion.

이 실험에서는 α-Al2O3 지지체 위에 진공 코팅(vacuum coating)과 딥 코팅(dip-coating) 기법을 사용하여 GO/γ -Al2O3 중간층을 형성하였고, 무전해도금 방식을 통해 Pd-Ag 수소 분리막을 제작하였다. Pd와 Ag는 각각 무전해도금을 통해 지지체 표면에 증착되었으며, 합금화를 위해 도금 과정 중 H2 분위기 하에서 500°C에서 18 h 동안 열처리를 진행하였다. 제 조된 분리막의 표면과 단면은 SEM을 통해 분석되었으며, Pd-Ag 분리막의 두께는 1.88 μm, GO/γ-Al2O3 중간층을 가진 Pd-Ag 분리막의 두께는 1.07 μm로 측정되었다. EDS 분석을 통해 Pd-77%, Ag-23%의 조성으로 합금이 형성된 것을 확인하 였다. 기체투과 실험은 H2 단일가스와 H2/N2 혼합가스를 이용하여 수행되었다. H2 단일가스 투과실험에서 450°C, 4 bar 조건 하에서 Pd 분리막의 최대 H2 플럭스는 0.53 mol/m²·s로, Pd-Ag 분리막의 경우 0.76 mol/m²·s로 측정되었다. H2/N2 혼합가스 실험에서 측정된 분리막의 separation factor는 450°C, 4 bar 조건에서 Pd 분리막이 2626, Pd-Ag 분리막이 13808로 나타났다.

이 논문은 남한지역을 대상으로 전기청동기시대의 주거와 환호, 청동기 부장 분묘, 대형 주구묘와 군집묘의 형성, 청동기 소유 주거, 환구 취락의 조성과 운영 등에 주목하여 당시의 사회구조에 대해서 검토한 글이다. 주거공간에서 확인되는 주거 간의 차별화는 취락을 이끄는 지도자 또는 유력자 및 그 의 가족들과 나머지 취락 구성원 간의 차이를 반영하는 것으로 파악하였다. 내환호와 외환호를 경계 로 배치된 대형 주거와 소형 주거의 분포 양상을 갖는 환호취락의 사례가 이를 잘 보여준다. 청동기를 소유한 주거의 존재와 청동 무기를 부장한 분묘의 등장은 요동지역 비파형동검문화와 관련된 것으로 긴장, 갈등, 대립 관계의 산물이면서 당시 사회의 계층분화적, 무장적 성격을 반영한다. 신성한 의례 공간인 환구, 그리고 이와 관련한 대형 가옥의 배치 양상은 엘리트 제사장의 존재를 추정할 수 있는 근거로 볼 수 있다. 이를 통해서 볼 때 전기청동기시대의 사회구조는 상위계층과 일반계층으로 구성 된 것으로 추정된다. 상위계층은 취락의 지도자(권위자)이면서 제사장의 성격을 가지는데, 이 상위계 층의 지위는 한시적인 성취 지위에 해당한다. 남한지역의 전기청동기 사회는 복합사회로 향해가는 긴 여정에서 중요한 기폭제가 되는 시기로 볼 수 있다. 이전 시기에 보이지 않았던 환호와 환구, 분묘와 청동기의 등장과 발전 양상은 전기청동기시대가 사회복합도가 증가한 서열사회에 해당한다는 것을 말 해준다.