This study presents a seismic fragility assessment methodology incorporating the cumulative damage effects of repeated seismic loading on structures. Conventional seismic fragility assessment methods typically focus on single earthquakes across multiple structures; however, seismic events often occur in sequences, with each event adding cumulative damage that can amplify the overall damage. Ignoring the effects of repeated earthquakes in fragility assessments may lead to underestimating seismic risk. This study proposes a simplified but efficient fragility assessment method that accounts for repeated earthquake effects using probabilistic combinations of each damage state. This procedure applied the capacity spectrum method to consider capacity degradation from displacement caused by prior earthquakes. Applying various earthquake scenarios, this study analyzes the effects of damage accumulation from earthquake occurrence sequences, structural behavior types, and seismic design levels on the fragility of structures under repeated earthquake events.

이 연구의 목적은 척추 자기공명영상 검사 시 기존의 포화 펄스와 함께 호흡 유도하(respiratory triggering, RTr) 기법을 적용하는 것이 영상화질 개선에 있어 효과적인지를 평가해 보기 위함이다. 이에 본 연구는 2024년 2월부터 2024년 10월까지 척추 MRI 검사를 받은 환자를 대상으로 분석하였다. 사용된 장비는 GE 사의 3.0T SIGNA Premier을 사용하였고, 축상 T2강조영상에서 동일한 부위를 RTr 기법을 적용하지 않은 영상과 RTr 기법을 적용한 영상 두 개를 획득해 평가하였다. 정성평가는 2명의 평가자의 평가점수를 Wilcoxon test로 비교하였다. 정성평가 결과, 경추와 요추에서는 RTr 기법 적용 시 영상화질 개선에 있어서 유의미한 차이를 보이지는 않았지만 흉추에서는 RTr 기법 적용 시 영상화질 개선에 있어서 유의미한 차이를 보였다. 결론적으로 경추와 요추보다는 포화펄스 사용에 있어 제한이 있고 호흡에 영향을 많이 받는 흉추 MRI 검사 시 RTr 기법을 적용하는 것이 더 효과적이다. 다만 RTr 기법 적용 시 검사 시간이 늘어나는 단점이 있어서 환자의 상태에 맞춰 검사하는 것이 요구되는 바이다.

본 연구에서는 2023년 전라남도 내 유통 수산물 중 동 물용의약품 모니터링을 하였다. 수산물 124건에 대하여 동 물용의약품 136종을 식품공전 수산물 중 동물용의약품 동 시 다성분 시험법으로 모니터링 하였다. 검사결과 잔류허 용기준 이하로 검출된 시료는 16건(13%), 검출되지 않은 시료는 108건(87%)으로 나타났다. 동물용의약품이 검출된 수산물은 광어, 조피볼락, 도미, 미꾸라지 4종으로, 검출된 잔류동물용의약품은 엔로플록사신, 옥시테르라사이클린, 트리메토프림, 아목시실린이 각각 검출되었다. 동물용의약 품 잔류허용기준이 초과한 수산물은 없었으나 동물용의약품이 잔류한 수산물이 꾸준히 검출되고 있어 안전한 수산 물 유통을 위해서는 모니터링을 강화하여야 할 것으로 생 각된다.

식품 첨가물의 목적은 크게 다르지만, 주로 주요 재료 의 품질을 향상시키거나 안정성을 유지하기 위해 사용하 고 있다. Boric acid는 유럽 연합(EU)에서 식품 첨가물로 허가된 상황이다. 그러나 한국에서는 사용이 허가되어 있지 않은 실정이다. 또한 국내에서는 식품 중 boric acid의 분석 방법이 보고된 적이 없다. 따라서 본 연구에서는 caviar에서 boric acid을 검출하기 위한 분석 방법을 개발 하고 이를 검증하였다. 본 연구에서는 inductively coupled plasma-atomic emission spectroscopy (ICP-AES)를 사용하 여 caviar에 존재하는 boric acid를 측정하였고, 또한 ICPMS를 이용하여 추가적인 정성분석이 가능한 분석법을 확 립하였다. 본 연구에서는 ICP-AES를 사용하여 caviar에서 boric acid의 정량 분석 방법을 확립하였다. 확립된 분석방 법의 유효성 검증을 위해 직선성, 일내 및 일간 정밀도, 정 확도, 검출한계(limit of detection, LOD), 정량 한계(limit of quantification, LOQ) 및 회수율을 포함한 방법 검증을 수행 하였다. 그 결과 검량선은 0.2 μg/mL에서 10 μg/mL 범위에 서 결정계수가 0.99이상인 것을 확인하였다. 검량곡선의 각각의 표준용액에 대한 정밀도는 0.9% 이하로 확인되었 고, 정밀도는 1.3% 이하, 정확도는 98.9-100.6%로 확인하 였다. 검량선 내 서로 다른 농도 3가지 0.5, 2, 10 μg/mL 의 농도에 대한 일내, 일간 정밀도와 정확도를 측정 결과 일내 정밀도는 0.4-0.6%, 정확도는 99.1-100.6%로 확인되 었다. 일간 정밀도는 0.5-2.1%, 정확도는 96.8-100.2%로 확 인되었다. 검출 한계(LOD)와 정량 한계(LOQ)는 각각 0.03 μg/mL와 0.16 μg/mL로 확인되었다. Boric acid의 회 수율 확인결과 0.5, 2 및 10 μg/mL 농도에서 98.0-102.0%, 상대 표준 편차(RSD)는 0.1%-0.4% 사이로 확인되었다. 측 정불확도의 경우 95% 신뢰구간(k=2)에서 불확도(U)는 203.1±10.8 mg/kg으로 산출되었다. 확립된 분석법을 적용 하여 국내외 유통되는 caviar 및 다양한 가공 식품 중에 존재하는 boric acid 와 sodium tetraborate에 잔류량을 측 정한 결과 총 104개의 시료 중 33개 제품에서 46.0-3942.2 mg/kg의 boric acid가 검출되었다. 따라서 본 연구 결과는 국내에 미설정 되어있는 식품첨가물 중 보존료의 기준 규 격 설정 및 관리 나아가 독성 실험을 위한 참고 자료가 될 수 있다고 판단된다.

꽃노랑총채벌레는 다양한 작물에 직간접적 피해를 일으키는 흡즙성 해충으로 살충제 저항성 검정 실험 등을 위한 실험 곤충으로 사육되고 있 다. 본 연구에서는 여러 가지 방법으로 꽃노랑총채벌레를 사육한 결과 시간과 공간을 절약할 수 있는 개선된 사육법을 개발하여 소개하고자 한다. 주요 개선된 점으로는 수확한 떡잎을 씻지 않고 그대로 사용하며 채란 시기에는 채란용 떡잎의 건조를 막기 위해서 사육통 내 수분을 적절히 공급해 주고, 알부터 약충 후기까지는 과습을 방지하기 위해 수분 공급을 줄이고, 약충 후반기부터 번데기가 우화 시기까지는 수분 공급을 다소 늘리는 방법 을 포함한다. 이 방법은 특히 약충과 번데기 시기에는 사육통을 층층이 쌓을 수 있으며, 성충기에도 채란용 통을 계단식으로 쌓아둘 수 있어 공간을 효율적으로 사용할 수 있게 한다. 이러한 개선된 사육법을 통해 사육통이나 채란통 준비 작업 시간을 단축할 수 있었으며, 채란통이나 약충 및 번데 기 사육통의 사육 면적을 93%로까지 줄일 수 있었다. 성충 생산 수는 사육통 하나 당 적게는 50~100마리 많게는 150~200 마리까지도 가능하였다.

Processing of medicinal plants and mushrooms plays a crucial role in oriental medicine. This study investigated the antioxidant potency and chemical composition of antler-shaped Ganoderma lucidumprocessed under different heating temperatures (120 to 180 °C) and times (10 to 20 minutes). Processed samples were analyzed for their antioxidant activities, including total phenol content, DPPH, ABTS radical scavenging capacity, NO assay, ROS scavenging capacity, and chemical composition changes. Antioxidant potency was highest with processing at 180 °C for 10 min and at 210 °C for 10 min. This enhanced activity is likely attributed to changes in compound functional groups due to heat processing, which in turn influences antioxidant activity. In contrast to antioxidant potency, chemical components, including ganoderic acid D, ganodermanonitriol, and ergosterol, showed decreasing trends with increasing temperature and time.

This review examines the importance of measuring practical enteric methane emissions from ruminants, considering their significant impact on global warming. Global warming is significantly driven by an increase in greenhouse gases, with rising methane (CH4) emissions from ruminants accelerating global warming recently. To successfully mitigate CH4 emissions and establish effective strategies, it is essential to apply reliable measurement techniques. This will allow for an accurate assessment of on-farm CH4 emissions. The priority should be to gather CH4 emission data that reflects the actual state of CH4 emissions from ruminants. The review provides an overview of the methods used to measure CH4 emissions from ruminants by compiling existing researches. It introduces the concepts, principles, and limitations of these methods to facilitate comparisons between existing approaches. This review discusses methods for measuring enteric CH4 emissions from ruminants at the farm level, including the tracer technique, laser methane detector, GreenFeed, and sniffer system. These methods are highlighted as potential tools to accumulate substantial data on on-farm CH4 emission from domestic animals with provides examples of international cases. Among these, this review introduces the Sniffer method, a CH4 emission measurement techniques that are suitable for on-farm use under domestic conditions, and emphasizes the necessity of its application. In addition, by presenting international cases where predictive models were developed based on on-farm CH4 measurement techniques, it is projected that if predictive models for CH4 emissions are developed by accumulating data at the farm level, it can contribute to sustainable livestock industry in various promising ways.

This study proposes a steel plate retrofit method and a polyurea method to improve the structural stability and usability of a factory floor slab with a thickness of 120mm. To assess vibration changes, vibrations were measured before and after retrofit. A numerical analysis model was also developed to evaluate improvements in structural safety and usability. The natural frequency increased from 11.4Hz to 17Hz through steel plate reinforcement, confirming an increase in slab stiffness. The damping ratio increased from 2.3% to 3.2% with polyurea reinforcement, indicating improved vibration reduction. Additionally, numerical analysis modeling showed that the natural frequency increased from 13.9Hz to 16.2Hz due to the steel plate reinforcement, enhancing the dynamic characteristics of the floor slab and confirming the reliability of the analysis model.

This study proposes an economically affordable method for retrofitting non-seismic detailed roof reinforced concrete beam-column joints (BCJs). The proposed method presents an innovative arrangement of steel plates designed to delay the propagation of joint shear cracks by externally applying compressive stress to the area surrounding the BCJs. Two full-scale sub-assemblage specimens for each exterior and interior roof BCJ, i.e., control and retrofitted specimens, were subjected to reversed cyclic loading to evaluate the proposed method. The retrofitted specimens displayed a preferable ductile behavior to the corresponding control specimen, with an enhancement in lateral strength by at least 100%. Furthermore, retrofitted specimens dissipated up to 13 times more energy than the control specimen by initiating a plastic hinge on beams or columns. These results indicated the effectiveness of the proposed method in preventing joint shear failure and improving the seismic behavior of roof BCJs.

This study points out the traffic safety inhibition problem in which the yellow time length at a signal intersection can be set differently depending on the tram, and proposes a way to overcome it. This study proposes a twofold approach for trams to coordinate with the yellow signal phase designated for general vehicles, utilizing a schedule-speed-based operating speed adjustment and departure time control at stations. To validate the proposed method, simulations were conducted for a planned tram corridor in the Wirye District, Seoul. The simulation environment was developed using the simulation of the urban mobility model. The operational characteristics of tram services in the main and branch-line sections were analyzed. In the upstream section of the mainline, the operating speed was 22.04 km/h, with a total dwell time of 400 s across 10 stations, resulting in zero intersection stops. Regarding the downstream section, the operating speed was 17.71 km/h, and one intersection stop was observed. In contrast, for the upstream section of the branch line, the operating speed was 14.73 km/h and there were two intersection stops, while the downstream section yielded an operating speed of 18.12 km/h, and also comprised two intersection stops. This study examined a novel operational strategy for trams near intersections along tram corridors without directly modifying the signal system. This strategy effectively utilizes tram stop dwell time and traffic signal information. It focuses on adjusting tram speeds to ensure smooth and safe passage through signalized intersections and optimizing operations so that trams approach and cross intersections at a consistent speed. Designed as a universal model, this strategy is adaptable to various regions and environments, rather than being limited to a specific area. It is expected to support tram operation planning by considering diverse factors, such as urban structure, traffic density, and intersection characteristics. Moreover, it provides valuable guidance to ensure the punctuality and stability of tram operations in a range of urban and traffic contexts.

Nitrogen-doped carbon nanomaterials (N-CNMs) were prepared using Ni(NO3)2 as a catalyst in the laminar diffusion flame. Doping the structure of carbon nanomaterials (CNMs) with nitrogen can significantly change the characteristics of CNMs. The purpose of this research is to study the effect of adding ammonia ( NH3) on the evolution of CNMs structure in the laminar flame of ethylene. Raman analysis shows that the intensity ratio ( ID/IG) of the D-band and G-band of N-CNMs increases and then decreases after the addition of NH3. The intensity ratio is a maximum of 0.99, which has a good degree of disorder and defect density. The binding distribution of nitrogen was analyzed by X-ray photoelectron spectroscopy (XPS), and a correlation was found between the amount of nitrogen and the morphology of N-CNMs. Nitrogen atoms predominantly present in the forms of pyrrolic-N, pyridinic-N, graphitized-N and oxidized-N, with a doping ratio of nitrogen atoms reaching up to 2.44 at.%. This study found that smaller nickel (Ni) nanoparticles were the main catalysts for carbon nanotubes (CNTs), and their synthesis followed the ‘hollow growth mechanism’ and carbon nanofibers (CNFs) were synthesized from larger Ni nanoparticles according to the ‘solid growth mechanism’. Furthermore, a growth mechanism for the synthesis of bamboolike CNTs using a specific particle size of the Ni catalyst is proposed. It is noteworthy that the synthesis and modulation of high-performance N-CNMs by flame method represents a simple and efficient approach.

This study delves into the potential application of whisker carbon nanotube (w-CNT) in terms of electrical heating performance, with a particular emphasis on its significance in high-efficiency electrothermal conversion applications. Meanwhile, a comparative study was conducted on traditional carbon nanotubes (T1 and T3) with different aspect ratios. A uniform and dense carbon nanotube paper (BP) was prepared using a vacuum filtration method, including single-layer (T1, T3 and w-CNT BP), double-layer gradient composite (T1/T3-g, w-CNT/T3-g), and mixed composite (T1/T3-m and w-CNT/T3-m). The thickness of each type of BP is approximately 100 μm. The results demonstrated that electrical conductivity and electrical heating performance of single-layer BPs follow the order of T1 > T3 > w-CNT. While, mixed composite BPs are superior to double-layer gradient composite BPs in electrical conductivity and thermal performance. Notably, w-CNT/T3-m BP exhibits excellent electrothermal performance. Under an applied voltage of 5 V, the surface temperature of w-CNT/T3-m BP reaches 190 ℃. When the voltage is increased to 6 V, the surface temperature rises by 150℃ within 10 s, reaching a steady-state temperature of 318 ℃. This excellent electrothermal performance can be attributed to the introduction of w-CNT, which has a perfect and defect free structure according to Raman analysis. In-depth analysis using X-ray diffraction (XRD) indicated a more complete and higher degree of crystallinity in the w-CNT structure. In summary, this study not only provides experimental and theoretical basis for the application of high-performance electrothermal materials based on carbon nanotubes, but also foreshadows their broad application prospects in the field of macroscopic materials.

In this study, ferric phosphate precursors were prepared by controlling precipitation time, and the resulting LiFe PO4 active materials were thoroughly investigated. Microscale LiFePO4 cathode materials, designed for high energy density at the cell level, were successfully synthesized through a 10 h co-precipitation. As the reaction time increased, smaller primary particles were aggregated more tightly, and the secondary particles exhibited a more spherical shape. Meanwhile, ammonia did not work effectively as a complexing agent. The carbon coated LiFePO4 (LiFePO4/C) synthesized from the 10 h ferric phosphate precursor exhibited larger primary and secondary particle sizes, a lower specific surface area, and higher crystallinity due to the sintering of the primary particles. Enhanced battery performance was achieved with the LiFePO4/C that was synthesized from the precursor with the smaller size, which exhibited the discharge capacity of 132.25 mAh ‧ g-1 at 0.1 C, 70 % capacity retention at 5 C compared with 0.1 C, and 99.9 % capacity retention after the 50th cycle. The better battery performance is attributed to the lower charge transfer resistance and higher ionic conductivity, resulting from smaller primary particle sizes and a shorter Li+ diffusion path.

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.

This study is about the evaluation for shock-proof performance of the system, elastically support the low accumulator of the naval artillery against underwater explosion, using DDAM. For the evaluation, the shock analysis procedure using DDAM, supported by MSC/NASTRAN, was briefly described. In addition, in order to perform the shock analysis, the elastic support system was modeled as a finite element. The shock analysis of the elastic support system was performed by selecting the analysis frequency range so that reliable results can be obtained. Finally, the shock-proof performance of the system was evaluated by comparing the shock analysis results with the properties of the elastic support system.

Robots equipped with artificial intelligence technology include learning functions. Purely inductive learning methods formulate general hypotheses by finding empirical regularities over the trainning examples. Purely analytical methods use prior knowledge to derive general hypotheses deductively. Therefore, when the physical environment of a robot is complex, there is a problem of increased computational time required for information processing. In particular, when a large number of robots transmit information, more computational time is required for information processing. The distance-based topological method proposed in this paper first constructs the topology based on the distances between robots, and then generates information weights according to the stages of the topology. The technique proposed in this paper has been experimentally confirmed to have excellent performance in environments with a large number of robots and complex physical conditions.

최근 개발 및 상용화가 되는 해상풍력발전기의 용량이 15MW로 증가하면서 나셀 중량의 증가와 함께 블레이드와 타워의 크기 가 증가하고 있다. 원통 형상의 타워는 단순한 구조 형상을 갖고 있지만 블레이드가 회전하면서 발생하는 추력과 모멘트, 나셀과 블레이 드의 자중 그리고 타워 자체가 받는 풍하중에 매우 안전하게 지지해야 하는 아주 중요한 구성 요소이다. 다른 요소에 비해 파손이 발생하 면 파생되는 손실 위험도가 매우 크고 풍력발전기 가격의 25%를 차지한다. 본 연구의 주요 대상은 풍력발전기 타워이며, 복잡한 시간 이 력 하중 조합에 의한 구조 안전성 평가를 더욱 직관적으로 검증할 수 있는 단순화된 평가법을 제안하고자 한다. 구조 안전성 평가를 위해 서 사용된 프로그램은 NASTRAN이며 적용 하중은 풍력발전기 해석을 통하여 계산된 면내 전단하중 정보를 적용하였다. 신속한 구조 안 전성 검토를 위하여, 복잡한 하중 조합 조건을 단순화하고, 극한하중과 좌굴 그리고 피로수명까지 순차적으로 검토하였다. 유한요소해석 법에 따른 최소 수명 지점인 can 용접부를 EUROCODE 3에 의해서 계산하면 112.5년으로 평가하며 변동 피로 하중을 고려하는 방식이 다르고, 코드에서는 경험 계수를 고려하고 있어서 직접 비교는 어렵지만 유사한 경향은 확인할 수 있었다. 연구를 통하여 제시된 면내 하중 조합법을 이용하면 이른 시일 안에 타워의 구조 안전성을 검증이 가능하며 이에 따라 최종중량에 대한 확신을 높일 수가 있다.