The rate of resistant pest emergence has accelerated due to the continuous use of pesticides. Therefore, it is important to formulate insecticide resistance management measures and effective control methods for pest. Bemisia tabaci, a greenhouse pest, causes direct damage to crops such as growth inhibition and leaf discoloration at all developmental stages except for eggs. It also indirectly damages plants by secreting honeydew, which covers surrounding leaves and fruits, leading to sooty mold development. In this study, eight insecticides with high usage rates, categorized by their mode of action, were selected. Samples of Bemisia tabaci were collected from six regions, and resistance analysis were conducted. The results showed that Flonicamid exhibited a resistance ratio of 8.91 in Sejong, while Pyriproxyfen showed a high resistance ratio of 63.56 in Gunwi. Fluxametamide, Spinetoram, Cyantraniliprole, Dinotefuran, Pyridaben, and Milbemectin displayed resistance ratio ranging from 0.02 to 1.14 in most regions, except for Flonicamid and Pyriproxyfen.

담배가루이(Bemisia tabaci)는 국내 주요 농업 해충으로서 고추, 오이, 토마토 등의 시설재배 작물에 큰 피해를 입힌다. 담배가루이는 작물을 흡즙하여 식물체의 상태를 악화시키고 TYLCV(tomato yellow leaf curl virus)등 100 여 종의 바이러스를 매개하며, 배설물을 통해 그을음병을 유발한다. 가장 일반적인 담배가루이의 방제방법은 빠르고 높은 효과를 지닌 살충제 살포이다. 하지만, 지속적인 화학적 방제는 해충의 살충제 저항성을 야기한다. 살충제 저항성은 방제 효율 감소와 농가의 경제적 손실을 일으킨다. 본 연구는 국내 지역별 시설 고추 재배지에서 발생한 담배가루이의 약제별 저항성을 조사하여, 지역별로 효과적인 약제 선정 및 대체 약제 추천 등 지속 가능한 해충관리법을 제시하고자 한다. 담배가루이는 전국 13개(파주, 양평, 화성, 횡성, 당진, 천안, 공주, 예천, 구미, 사천, 남원, 나주, 고흥) 지역에서 채집되었다. 작용기작 별 사용량이 많은 8종을 선정하였으며, 엽침지법을 사용 하여 살충률을 확인하였다. 곤충생장조절제(insect growth regulators, IGR)인 피리프록시펜계 약제는 알을 대상 으로, 그 외 7개 약제는 2령약충을 대상으로 살충률을 확인하였다. 높은 살충력을 보인 약제는 아버멕틴, 밀베마 이신계, 스피노신계, METI살충제, 디아마이드계 약제이다. 아버멕틴, 밀베마이신계는 권장사용농도로 처리 시 최소 84.5%, 최대 100% 살충률을 보였다. 스피노신계는 최소 86.3%, 최대 90.6% 살충률을 보였으나 천안, 파주, 사천에서 각각 59.7%, 66.6%, 79%로 다른 지역에 비해 상대적으로 낮은 살충률을 보였다. METI살충제는 최소 81.1%, 최대 98% 살충률을 보였으나 나주, 예천, 천안, 사천이 각각 61.6%, 68.8%, 68.9%, 69.2%의 상대적으로 낮은 살충률을 보였다. 디아마이드계는 최소 83.9%, 최대 91.9% 살충률을 보였으나 천안과 구미가 각각 56.6%, 59.8%로 상대적으로 낮은 살충률을 보였다. 낮은 살충력을 보인 약제는 네오니코티노이드계, 설폭시민계, 테트 론산 및 테트람산 유도체, 피리프록시펜계 약제이다. 네오니코티노이드계는 최소 14.1%, 최대 41.9% 살충률을 보였다. 설폭시민계는 최소 17%, 최대 42.8% 살충률을 보였다. 테트론산 및 테트람산 유도체는 최소 30.5%, 최대 54.9% 살충률을 보였으나 천안이 14.4%로 특히 낮은 살충률을 보였다. 피리프록시펜계는 최소 55.3%, 최대 64.3% 살충률을 보였으나 횡성이 72.2%로 상대적으로 높은 살충률을 보였으며, 파주가 35%로 상대적으로 낮은 살충률을 보였다. 실험 결과를 통해 살충제 별 살충력의 차이와 지역별로 살충률의 차이를 확인하였다. 본 연구결 과를 통해 효과적인 약제 추천과 지역에 따라 다른 방제 전략 제시에 도움이 되고자 한다.

The Varroa mite, Varroa destructor, a parasitic mite that afflicts honey bees, has become increasingly resistant to acaricides like fluvalinate due to its widespread use. The target site insensitivity mechanism, mediated by the L925V/M/I mutations in the voltage-gated sodium channel, plays a major role in resistance. Additionally, cytochrome P450 monooxygenases (Cyp450s) appear to function as a metabolic resistance factor; however, no Cyp450-mediated resistance mechanism has been reported to date. The aim of this study was to identify and characterize Cyp450s associated with fluvalinate resistance. A synergistic bioassay confirmed the involvement of Cyp450s in conferring tolerance or resistance to fluvalinate. Correlation analysis between mortality data and the expression levels of Cyp450 genes led to the identification of several candidates that may play a crucial role in fluvalinate resistance. Analysis of tissue distribution patterns revealed that these genes were most abundantly expressed in the cuticle and synganglion. This suggests that, despite their relatively low expression level, they may play a critical role in protecting the target site from fluvalinate due to its predominant expression in neuronal tissues. Functional analysis, in conjunction with baculovirus expression, demonstrated that fluvalinate has high inhibition rates against the recombinant candidate Cyp450s, suggestive of their strong interaction with fluvalinate. We discussed the potential utilization of their expression levels as a molecular marker for diagnosing metabolic resistance in field-collected Varroa mites.

To elucidate the mechanism of pyrethroid resistance in Helicoverpa armigera, the study explored three possibilities based on deltamethrin as a model pyrethroid; 1) the existence of mutations in the target site of deltamethrin, 2) the existence of variation at the genomic level between insecticide-susceptible and resistant strains, 3) differences in gene expression patterns between the strains. Based on these hypotheses, three levels of resistant strains and a susceptible strain as well as nine Korean field populations were used. As results, 1) any point mutations were not detected in sodium channel gene. 2) based on newly set Korean reference genome (GCA_026262555.1), approximately 3,369,837 and 1,032,689 variants (SNPs and Indels) were revealed from genome and ORFs, respectively. However, any specific variants were not found to be highly correlated with the level of insecticide resistance. 3) based on DEG analysis, some of detoxification enzyme genes were differently expressed particularly cytochrome P450 genes. Therefore, H. armigera possibly acquires deltamethrin resistance through a combination of actions, including over-expression of various detoxification enzymes such as CYP3 subfamilies and cuticular proteins.

The Varroa mite, Varroa destructor is an ectoparasite that parasitizes honey bees. The widespread usage of acaricides, particularly fluvalinate, has resulted in the emergence of resistance in Varroa mite populations all over the world. The goal of this study is to track fluvalinate resistance in Varroa mite field populations in Korea using both bioassay and molecular markers. To accomplish this, a residual contact vial (RCV) bioassay for on-site resistance monitoring was developed. Early mortality evaluation in the RCV bioassay was effective for reliably separating mites with the knockdown resistance (kdr) genotype, but late mortality evaluation was useful for distinguishing mites with additional resistance factors. The RCV bioassay of 14 field mite populations collected in 2021 revealed potential resistance development in four populations. Quantitative sequencing was used as an alternate method to examine the frequency of the L925I/M mutation in the voltage-gated sodium channel (vgsc), which is related with the fluvalinate kdr phenotype. While the mutation was not present in Varroa mite populations in 2020, it appeared in 2021, rose in frequency in 2022, and was practically ubiquitous across the country by 2023. This recent emergence and rapid spread of fluvalinate resistance within a span of three years demonstrate the Varroa mite's significant potential for developing resistance. This situation emphasizes the critical necessity to replace fluvalinate with alternate acaricides, such as fenpyroximate, coumaphos, and amitraz. A few novel vgsc mutations potentially involved in resistance were identified. Potential factors driving the rapid expansion of resistance were further discussed.

본 연구에서는 콘크리트의 내구성 및 낮은 인장강도를 향상시키기 위해 개발된 폴리비닐알콜(PVA) 혼입 시멘트 복합 체의 내약품성을 평가하였다. 시멘트 복합체에 대한 PVA 혼입률은 0%, 1.0%, 1.2%로 설계되었다. 각 혼입률에 따른 시멘트 복 합체의 압축강도, 인장강도, 휨강도를 측정하였다. 결과적으로 1.2% 혼입률에서 압축강도는 1.3배, 인장강도는 5.6배, 휨강도는 17.9배 증가하였다. 내약품성 실험을 위해 염화칼슘, 황산나트륨, 그리고 황산 용액에 시멘트 복합체를 침지시킨 후 30일, 40일, 50일 후 질량 소실률을 측정하여 내화학성을 평가하였다. 내화학성 실험 결과, PVA 혼입은 약품의 침투를 방지하여 시멘트 복 합체의 내화학성을 향상시키는 것으로 나타났다. 총체적으로, PVA 혼입은 시멘트 복합체의 내화학성을 향상시키는 동시에 강도 특성을 제공하는 것으로 확인되었다.

PURPOSES : The numeric-based Highway Pavement Management System (HPMS), along with an advanced three-dimensional pavement condition monitoring profiler vehicle (3DPM), in South Korea has presented remarkable advancements in pavement management since the early 2000. Based on these results, visual distress on pavement surfaces can be easily detected and analyzed. Additionally, the entire expressway pavement surface conditions in South Korea can be easily monitored using the current graphical user interface-based advanced information graphic (AIG) approach. Therefore, a critically negative pavement section can be detected and managed more easily and efficiently. However, the actual mechanical performance of the selected pavement layer still needs to be investigated in a more thorough manner not only to provide more accurate pavement performance results but also to verify the feasibility of the current 3DPM and AIG approaches. In this study, the low-temperature performance of the selected asphalt pavement layer section was evaluated to further verify and strengthen the feasibility of the current 3DPM and AIG approaches developed by the Korea Expressway Corporation. METHODS : Based on 3DPM and AIG approach, the positive and negative-riding-quality road sections were selected, respectively. The asphalt material cores were extracted from each section then bending beam rheometer mixture creep test was performed to measure their low-temperature properties. Based on the experimental results, thermal stress results were computed and visually compared. RESULTS : As expected, the asphalt material from the negative driving performance section presented a poorer low-temperature cracking resistance than that from the positive driving performance section. CONCLUSIONS : Current 3DPM equipment can successfully evaluate expressway surface conditions and the corresponding material performance quality. However, more extensive experimental studies are recommended to verify and strengthen the findings of this study

The influence of specimen geometry and notch on the hydrogen embrittlement of an SA372 steel for pressure vessels was investigated in this study. A slow strain-rate tensile (SSRT) test after the electrochemical hydrogen charging method was conducted on four types of tensile specimens with different directions, shapes (plate, round), and notches. The plate-type specimen showed a significant decrease in hydrogen embrittlement resistance owing to its large surface-to-volume ratio, compared to the round-type specimen. It is well established that most of the hydrogen distributes over the specimen surface when it is electrochemically charged. For the round-type specimens, the notched specimen showed increased hydrogen susceptibility compared with the unnotched one. A notch causes stress concentration and thus generates lots of dislocations in the locally deformed regions during the SSRT test. The solute hydrogen weakens the interactions between these dislocations by promoting the shielding effect of stress fields, which is called hydrogen-enhanced localized plasticity mechanisms. These results provide crucial insights into the relationship between specimen geometry and hydrogen embrittlement resistance.

Technological breakthroughs, combined with the demographic challenges of an aging population and the aftermath of the COVID-19 pandemic, spur new business opportunities in the service robot industry. From a management perspective, these technologies are positively evaluated in terms of increasing productivity, new business opportunities, and financial benefits (Belanche et al., 2020). However, although automation and robotics have already gained attention in the tourism and hospitality industry, research on their use in restaurants and the customer's attitude toward these new service solutions is still limited (Berezina et al., 2019; Ivanov et al., 2019; Kuo et al., 2017).

공동주택 방화문의 화재성능 결함으로 인하여 하자소송이 확대되고, 화재발생 시 치명적일수 있다. 그러나 현행 법령은 이에대한 대책이 소홀한 편이다. 본 연구에서는 방화문의 결함과 특성 등을 잘 반영하고 있는 『강제창호 제작･품 질검수 매뉴얼』과 LH 설계･시방서 개정작업에서 드러난 문제점들에 대한 개 선방안을 제시하고자 한다. 방화문의 적정단가를 산정하고 내용연수를 합리적 으로 조정하며 3단계 점검시스템 등 관련규정을 신설 운영한다면, 방화문 품질 성능 향상과 화재시 입주민 보호에 크게 기여할 것으로 판단된다.

A two-hour fire-resistance PC hollow slab for residential use was developed to secure structural and fire-resistance performance and to be applied to the general building and apartment housing markets. Compared to the existing hollow slab, in order to secure the same or better structural performance and economic feasibility by reducing the quantity, it was attempted to secure the fire resistance performance by reducing the concrete filling rate in the cross section and adjusting the thickness of the upper and lower flanges by optimizing the hollow shape in the cross section of the slab. For structural performance evaluation, experiments were performed on PC hollow slabs by varying the member thickness and the presence or absence of overlaid concrete, and all of the experimental results showed that the design strength was sufficiently exhibited and that stability during construction was possible. The developed synthetic PC hollow slab has secured fire resistance and residential performance so that it can be applied to all buildings, and it is intended to be immediately applied to the field.

The rational evaluation of carbon-based conductive ink performance is critical to both industrial production and applications. Herein, a model to evaluate writing performance of conductive ink by line resistance was proposed by investigating possible relations among different parameters and establishing relevant model to estimate ink writing performance. Bulk conductive inks were prepared and characterized to provide samples for model. To improve the precision of model, the impact of external factors including writing speed and angle was studied. Nonlinear regression and back propagation artificial neural network were employed to estimate line resistance, and cross check validation was conducted to prove robustness and precision of model. Most importantly, the investigation will open up a new path for the exploration of other carbon-based handwritten electronic devices.

Since spent nuclear fuel (SNF) should be isolated from the human life zone for at least 106 years, deep geological disposal (DGD) is considered a strong candidate for SNF management in many countries. Therefore, a disposal canister should be nearly immune to corrosion in such a long-term storage environment. Even though copper has a low corrosion rate of a few millimeters per million years in geological environments, the corrosion resistance of the copper welds must be preferentially validated, which inevitably occurs during the sealing of the disposal canister after the SNF is loaded. This is because the weld zone is a discontinuous area of microstructure, which can accelerate uniform and localized corrosion. In this study, the microstructural characteristics of copper welds in different welding conditions such as friction stir welding, electron beam welding, cold spray, were analyzed, focusing on the formation of microstructure, which affects resistance to corrosion. In addition, the microstructure and corrosion properties of the copper weld zone manufactured by recent wire-based additive manufacturing (AM) technology were experimentally evaluated. From this preliminary test result, it was found that the corrosion characteristics of the welds produced by the AM process using wire are comparable to those of the conventional forged copper plate.

The purpose of this study was to examine whether galvanic corrosion of copper occurs by inserting a third barrier layer with a higher corrosion potential than copper between copper and cast iron when the copper layer is locally perforated by pitting or partial corrosion. A triple layer composed of copper, inserted metal, and carbon steel was manufactured by cold spray coating of inserting metal powders such as Ag, Ni, and Ti on carbon steel plate followed by Cu coating on it. First, the corrosion properties were evaluated electrochemically for each metal coating. As a result of Tafel plot anaylsis in KURT groundwater condition, the corrosion potential of Fe (-567 mV) was much lower than that of Cu (-91 mV), and the corrosion potential of Ni (-150 mV) was also lower than that of Cu. Therefore, Ni was likely to corrode before Cu. However, the corrosion current of Ni was lower than that of the Cu. In the galvanic specimen where the copper and inserting metal were exposed together, Cu-Fe was much lower corrosion potential of -446 mV, and the corrosion potential of Cu-Ti, Cu-Ni, and Cu-Ag were slightly higher than that of Cu. Therefore, it seemed that Ag, Ni, and Ti all might promote galvanic corrosion of surrounding copper when the copper layer was perforated to the inserted metal layer. If the metal insertion presented in this study operates properly, the disposal container does not need to worry about the partial corrosion or non-uniform corrosion of external copper layer.

The damage ratio of Spent Nuclear Fuel (SNF) is a very important intermediate variable for dry storage risk assessment which require an interdisciplinary and comprehensive investigation. It is known that the pinch load applied to the cladding can lead to Mode-3 failure and the cladding becomes more vulnerable to this failure mode with the existence of radial hydrides and other forms of mechanical defects. In this study, a sensitivity analysis was performed to evaluate the importance of the damage parameters that need to be calibrated for the simulation of zircaloy-4 cladding failure using computational mechanics. The simulation model was generated from a microscopic image of the cladding with hydride. The image segmentation method was used to separate the Zircaloy-4, hydride, and hydride- Zircaloy matrix interfaces to create a pixel-based finite element model. The ring compression test (RCT) was simulated because the resistance of the cladding under pinch load can be evaluated by this test. It was assumed that the damage starts with the formation and growth of voids or small cracks in the material, which grow and combine to form larger cracks, eventually leading to the complete fracture of the material. Therefore, the ductile damage criterion was applied to all materials to simulate crack formation and propagation. The sensitivity analysis was performed based on the design of experiments using L8 orthogonal array. The effects of five factors on the fracture resistance of hydrided cladding were quantified, and they are the fracture strains describing the damage initiation in zircaloy-4 matrix, hydride, and hydride-zirconium matrix, and yield stress and Young’s modulus for hydride-zirconium matrix. Information on those parameters are hardly available in literature and experimental data which enable the estimation of those are also very rare. It is planned to build a computational model which can accurately simulate the fracture behavior of hydrided cladding by calibrating significant fracture parameters using reverse engineering. The results of this study will help to figure out those significant parameters.