Maintaining stable operation of battery swapping stations under time-varying demand is an important issue in Advanced Air Mobility (AAM) operations. This study proposes a predictive control decision model that uses short-term demand information to proactively adjust swapping channels, charging resources, and available battery levels. Three operational strategies were compared: Fixed rule (S1), State response (S2), and Predictive control (S3). The system was modeled as a multi-resource service system with time-dependent aircraft arrivals, and each strategy was evaluated through 100 simulation replications under identical demand and facility conditions. The results showed that S3 reduced the average waiting time to 1.04 min, the waiting probability to 27.31%, and the battery shortage rate to 12.38%, corresponding to reductions of 98.32%, 64.39%, and 73.37%, respectively, compared with S1. In addition, S3 maintained fewer average active swapping channels and chargers than S2 while performing more frequent resource adjustments. These results demonstrate that short-term demand information can support proactive resource allocation and improve service performance and battery supply stability without simply increasing resource deployment.

Maintaining stable operation of battery swapping stations under time-varying demand is a critical issue in Advanced Air Mobility (AAM). This study proposes a stepwise capacity expansion strategy in which pre-secured standby swapping channels are sequentially activated when either queue length or longest waiting time reaches a predefined threshold. The main comparison was conducted between a two-channel fixed-capacity configuration (Fixed-2) and the stepwise expansion configuration (Stepwise), while a three-channel fixed-capacity configuration (Fixed-3) was additionally used as a benchmark. Using common random numbers, 100 simulation replications were performed under identical demand and operating conditions. Compared with Fixed-2, Stepwise reduced average waiting time by 88.48%, waiting probability by 50.80%, and average queue length by 88.76%, while throughput remained nearly unchanged. In the paired comparison, Stepwise showed a lower average waiting time in 99 of 100 replications and the same value in one replication. Sensitivity analysis showed that lower threshold values activated channels earlier and improved waiting performance, but increased the number of active channels. These findings indicate that stepwise activation can effectively mitigate congestion under model-based time-varying demand, although the threshold values should be interpreted as operating reference conditions rather than universal optima.

Advanced Air Mobility (AAM) systems require efficient ground infrastructures to support high-frequency operations, where battery swapping stations play a critical role. In such environments, energy supply stability significantly affects system performance, particularly under time-varying demand. This study analyzes the impact of different energy supply configurations on battery swapping station performance using a simulation-based approach. Three configurations are considered: external power grid, distributed energy resources (DER), and integrated DER with energy storage systems (ESS). Key performance metrics include average waiting time, system staying time, task completion rate, and battery availability. The results show that grid-based systems experience increased delays under peak demand, while DER-only configurations improve some performance indicators, but their effectiveness remains limited under highly time varying demand due to supply variability. In contrast, the integration of DER and ESS achieves the most stable performance by mitigating energy fluctuations. These findings indicate that the temporal adaptability of energy supply is a critical factor in determining operational performance, highlighting the importance of integrating energy storage systems in AAM infrastructure design.

Advanced Air Mobility (AAM) systems rely on high-frequency operations of electric vertical take-off and landing (eVTOL) aircraft, making the performance of ground energy infrastructure a critical factor for overall system efficiency and reliability. In particular, battery swapping stations function as service systems in which multiple aircraft arrivals share limited resources, inevitably leading to processing delays under stochastic demand conditions. Previous studies have primarily focused on optimization-based scheduling and simulation-driven performance evaluation. However, the probabilistic mechanisms governing delay generation and operational stability in battery swapping systems have not been sufficiently explored. This study presents a probabilistic operational analysis of battery swapping stations in AAM using queueing theory. The system is modeled as a multi-server queueing system with stochastic arrival and service processes, and key performance metrics—including system utilization, average waiting time, and delay probability are analytically derived. Furthermore, delay behavior is examined not only in terms of average values but also through probabilistic distributions and service-level-based performance criteria. To validate the proposed analytical framework, MATLAB-based discrete-event simulations are conducted under various operational scenarios, including different arrival rates and service time variability conditions. The results indicate that stochastic characteristics significantly influence delay behavior and system stability, particularly under peak demand conditions. The proposed approach provides a theoretical foundation for understanding delay dynamics in AAM battery swapping operations and offers practical insights for designing stable and efficient ground infrastructure systems.

This study presents an optimization model for battery scheduling in Advanced Air Mobility (AAM) operations considering congested (peak-hour) flight periods. Peak-hour demand concentration causes bottlenecks in vertiport charging/swapping facilities and accelerates battery degradation, reducing operational efficiency. A Mixed-Integer Linear Programming (MILP) model is developed, incorporating battery states (SoC, SoH), charger and swap-bay constraints, and power peak limits. Simulation results under peak and off-peak scenarios show that the proposed model reduces both delay time and total operating cost compared to average-demand scheduling. This study provides a quantitative decision-making basis for enhancing resource efficiency in AAM operations. The findings offer practical implications for improving AAM infrastructure efficiency and resource management policies.

Advanced Air Mobility (AAM) operations using electric vertical takeoff and landing (eVTOL) aircraft require reliable ground energy infrastructure to ensure stable service. During congested periods, temporally concentrated flight demand can cause delays and operational instability in battery swapping stations. This study examines the operational impacts of different energy supply configurations under demand variability. Three configurations are considered: an external power grid–only condition, a distributed energy resource (DER)–applied condition, and an integrated DER and energy storage system (ESS) condition. A discrete-time simulation model is used to evaluate operational performance in terms of average waiting time, task completion rate, and battery inventory stability. The results show that the integrated DER and ESS configuration provides the most stable performance during peak-demand periods, highlighting the importance of energy storage–based integrated supply structures for resilient AAM battery swapping infrastructure.

This study investigates the impact of solar paper panel tilt angles on the flight endurance of solar powered the drone. To address the limited flight time of conventional battery powered drones, photovoltaic solar paper panels were mounted at varying angles 0°, 15°, 30°, and 45° tested under consistent conditions. Experimental results showed that a 30° tilt angle produced the highest power output, leading to about 14% increase in flight duration compared to a flat configuration. These findings demonstrate that optimizing panel orientation significantly improves energy efficiency and drone performance. This work provides practical insight into the design of lightweight solar UAVs and highlights the feasibility of simple tilt adjustments as a low complexity alternative to active solar tracking systems.

This study explores educational strategies for cultivating skilled professionals in Korea’s Urban Air Mobility (UAM) sector. Based on the national K-UAM roadmap, it identifies training needs across three core domains: operation, maintenance, and infrastructure. A structured survey was conducted with 62 organizations involved in UAM development. Results reveal a strong demand for simulation-based emergency response training, AI-assisted diagnostics, and smart infrastructure operation. Key barriers include the shortage of interdisciplinary professionals and insufficient practice-oriented curricula. Using DACUM and CDIO frameworks, this research proposes a modular, domain-specific education model. The findings serve as a foundation for establishing future UAM workforce policies and academic programs.

과불화화합물은 소수성, 소유성, 내열성의 우수한 물성을 기반으로 다양한 산업군에 활용되어 왔으나, 환경 내 잔류성과 생체 독성으로 인해 음용수를 통한 인체 노출이 중요한 공중보건 문제로 대두되고 있다. 본 연구는 음용수 내 과불화화합물 규제의 국제적 규제 동향을 분석하고, 규제 설정 원리와 과학적 배경을 고찰하는 데 목적을 둔다. 먼저 미국, 유럽연합 등 주요 국가의 음용수 내 과불화화합물 규제 현황을 비교하고, 각국이 채택한 규제 대상 물질, 설정 농도, 그리고 기저 규제 철학을 분석하였다. 특히 본 연구에서는 미국의 독성 및 위해성 기반 과학적 규제 체계를 근거로, 과불화화합물의 독성참고치(RfD) 및 발암계수(CSF)가 어떻게 도출되고 규제 기준으로 변환되는지 단계적으로 설명하였다. 또한, 개별 과불화화합물의 위해성을 넘어서, 혼합된 과불화화합물의 누적 위해성(HI) 산정 방식의 과학적 배경을 함께 살펴보았다. 이러한 국제적 규제 진전에도 불구하고, 현재 우리나라의 경우 3종 과불화화합물만 수질감시항목으로 지정되어 있을 뿐, 인체 위해성에 기반한 법적 수질기준은 마련되지 않은 실정이다. 또한, 현재의 국내 감시체계에서는 다종 과불화화합물의 혼합 노출로 인한 누적 위해성을 평가하지 못하는 구조적 한계가 있다. 이에 본 논문은 국제적인 규제 동향과 과학적 기준 설정 원리를 종합적으로 분석하고, 주요 국가의 모범사례를 바탕으로 국내 과불화화합물 음용수 규제 체계의 발전을 위한 시사점을 제시하였다.

This study aims to prepare bamboo-based activated carbons with surface modifications, focusing on carbon dioxide (CO2) capture in public indoor spaces. The surface of the activated carbon adsorbents was chemically modified through three steps: carbonization, steam activation, and chemical treatment using potassium hydroxide (KOH) and potassium sulfamate (KSO3NH2). The specific surface area and pore volume of the obtained adsorbent (BSAC-KN) were 1,246 m2/g and 0.74 cm3/g, respectively. The surface modification resulted in an adsorption capacity of up to 3.79 mmol-CO2/ g-AC for carbon dioxide. In addition, the expansion of the specific surface area and the enhanced physico-chemical interaction between the weak acidic CO2 molecules and the basic AC surface improved adsorption capacity.

We study substrate support structures and materials to improve uptime and shorten preventive maintenance cycles for chemical vapor deposition equipment. In order to improve the rolling of the substrate support, the bushing device adopts a ball transfer method in which a large ball and a small ball are mixed. When the main transfer ball of the bushing part of the substrate support contacts the substrate support, the small ball also rotates simultaneously with the rotation of the main ball, minimizing the resistance that can be generated during the vertical movement of the substrate support. As a result of the improvement, the glass substrate breakage rate is reduced by more than 90 ~ 95 %, and the equipment preventive maintenance and board support replacement cycles are extended four times or more, from once a month to more than four months, and the equipment uptime is at least 15 % improved. This study proposes an optimization method for substrate support structure and material improvement of chemical vapor deposition equipment.

국문 우주항공 분야에서 널리 쓰이고 있는 하이드라진[hydrazine, N2H4]은 로켓연료로 사용되는 대표적인 추진제이지만 환경에 유해하고 독성이 강하다는 단점이 존재한다. 따라서 친환경적이고 독성 이 적은 추진제가 다양하게 개발되고 있다. 본 연구에서는 수산화아민[hydroxylamine, NH2OH]을 출발물질로 하여, 질산[nitric acid, HNO3]과 산-염기 반응을 통해 얻어지는 친환경 추진제 HAN [hydroxylammonium nitrate, NH3OHNO3]의 물리 화학적 특성에 대하여 적외선분광법을 이용하여 합성물의 조성, 화학구조 및 작용기를 관찰하였고, 열중량분석을 통해 HAN의 분해온도를 확인하였다. 이온 크로마토그래피를 통해 합성한 HAN에 함유되어 있는 질산이온의 함량을 측정하였다. 즉, N-H와 N-O의 IR peak가 3161 cm-1와 1324 cm-1에서 각각 나타나는 것을 통해 생성한 화합물이 HAN임을 확인하였고, pH 5-7 근처에서 합성한 HAN은 분해온도가 120-140℃인 반면, pH 8 정도인 HAN은 분해온도가 14 0℃ 이상임을 알 수 있었다. 한편, pH 6-7 사이에서 HAN을 합성하였을 때, 가장 높은 질산이온의 농도는 70%인 것으로 나타났다.

Alane(aluminum trihydride, AlH3)으로 명명되는 고에너지 물질인 삼수소알루미늄은 수소저장 물질로서 뿐만 아니라 우주항공분야의 고체 추진제나 방위산업의 화약제조용으로도 사용될 수 있다. 본 연구는 습식공정을 통하여 합성하고, 에테르를 세밀하게 분리하는 결정화 공정을 통하여 최종 수소화물을 추출하였다. 결정화 공정에서 삼수소알루미늄-에테레이트(AlH3·(C2H5)2O)가 alane으로 상변이하면서 입자가 성장하고, 85℃에서 2 시간의 결정화 시간이 이루어졌을 때 가장 안정된 결정상이 나타나는 모습을 확인하였다. 최종적으로 추출된 고체상 삼수소알루미늄은 막대모양의 γ-형태가 가장 많은 양을 차지하는 것으로 나타났으며, 크기는 50-100 μm 수준이었다

In the 21st century, information and communication technology (ICT) worldwide presents a new vision for agriculture. Time and place, as well as the high-tech industry, to overcome barriers to the fusion of the so-called "smart agriculture," are changing the agricultural landscape. Core container production in precision agriculture for mushroom cultivation, optimal temperature, humidity, irradiation, self-regulation of factors such as carbon dioxide, and environment for mushroom cultivation were adopted. Lentinula edodes (shiitake) is an edible mushroom native to East Asia, cultivated and consumed in many Asian countries. It is considered to be medicinal in certain practices of traditional medicine. We used different controlled light sources (Blue-Red-White-combined LED, blue LED, red LED, and fluorescent light) with different LED radiation intensities (1.5, 10.5, and 20.5 μmol/㎡s for LEDs) to compare growth and development. Mushrooms were treated with light in a 12-hour-on/ 12-hour-off cycle, and maintained in a controlled room at 19~21°C, with 80~90% humidity, and an atmospheric CO2 concentration of 1,000 ppm for 30 days. Growth and development differed with the LED source color and LED radiation intensity. Growth and development were the highest at 10.5 μmol/㎡s of blue LED light. After harvesting the fruit bodies, we measured their weight and length, thickness of pileus and stipe, chromaticity, and hardness. The 10.5 μmol/㎡s blue-LED-irradiated group showed the best harvest results with an average individual weight of 39.82 g and length of 64.03 mm, pileus thickness of 30.85 mm and pileus length of 43.22 mm, and stipe thickness of 16.96 mm with fine chromaticity and hardness. These results showed that blue LED light at 10.5 μmol/㎡s exerted the best effect on the growth and development of L. edodes (shiitake) mushroom in the ICT-system container-type environment.

선박엔진에서 발생하는 NOx 및 SOx 제거용 스크러버 폐세정액에 포함되어 있는 저농도상 의 질산 및 황산이온을 비료상 물질로 회수하고자 하였다. 본 연구에서는 네 가지 유기용매를 적용하여 선택적으로 추출하여 회수하는 방법을 시험하였다. 아세톤과 메틸알콜을 이용하여 추출한 질산암모늄과 디에틸에테르와 에틸알콜을 적용한 황산암모늄의 시료를 적외석흡수분광법(IR)을 이용하여 분석한 결과, 상용제품과 거의 동일한 구성성분으로 나타났다. 이때 폐수로부터의 회수율은 최대 89%와 80%까지 각 각 얻을 수 있었다. 따라서 배기가스 스크러버에 잔존해있는 질산이온과 황산이온에 대한 회수는 사용하 는 용매의 선택도 및 용해도가 핵심적인 요소인 것으로 판단된다.

전 세계적으로 증가하고 있는 선박 배출가스 규제를 위해 국제해사기구(IMO)는 배출되고 있 는 가스의 부정적 환경영향에 대한 부각과 함께 법적인 규제를 강화하고 있다. 국제해사기구(IMO) 규 제에 따라, 발트 해 연안을 지나는 모든 배들은 배출가스 제거창치를 장착해야 한다. 다양한 최신 탈황/ 탈질 장치가 소개되고 있는 가운데, 선박의 제한 된 공간을 활용한 폐 세정액 회수 공정 또한 중요한 기술로 발전 가능하다. 탈황/탈질 장치 후단에서 발생되는 폐 세정액은 질산암모늄, 황산암모늄과 같은 유용부산물을 포함하고 있다. 본 연구는 선택적 유기용매 염석 법, 저온 결정화 추출, 열 감압농축을 이 용하여 유용부산물로서 질산암모늄을 추출하였다. 열 감압농축으로 얻어진 부산물을 반복적 유기용매 추 출방법으로 정제했을 시 가장 높은 순도의 질산암모늄이 추출 되었다. 분석 장비를 통해 추출 된 유용 부산물의 성분 및 특성을 평가하였다.

Dinitramide(N(NO2)2)염 화합물은 현재 고체 산화제로 로켓추진제의 중요한 원료 물질 중 하나이며, 환경 및 인체에 독성이 적은 친환경 에너지물질로 알려져 군사적 목적 외에 다양한 가스발생 제로서 사용되고 있다. 특히 무기염이 아닌 유기염인 Guanidine 염(GDN)은 수분에 대한 안정성이 향 상되어 안정적 보관 및 제조가 가능하므로 고순도 물질의 대량 생산이 가능하다. GDN의 출발물질로 guanidine의 음이온 염인 acetate, chloride, carbonate, nitrate, sulfate를 사용하여, GDN(GDN-1,2,3,4,5)을 최대 99%의 수율로 합성하였고, 이들의 물성을 다양한 분석기기를 이용하여 평가하였다. 흡수파장은 3452, 3402, 3354, 3278, 3208, 1642, 1570, 1492, 1416, 1337, 1179, 1000 cm-1이 공통적으로 관찰되었으며, 열적 특성 변화는 130 ℃에서 일어나기 시작하며 150℃~160 ℃에서 는 발열반응과 함께 물질의 변화가 관찰되었다.

This study was aimed to compare the thoughts differences about the abandoned dog protectorate facility according to the presence of dog ownership. We evaluated 100 people who have dog ownership and 100 people who have not dog ownership by questionnaire survey including14 questions. The authors present the thoughts differences about the abandoned dog protectorate facility between people with or without dog ownership. These results may be used for the fundamental data for the establishment of strategy on the improved management of abandoned dog protectorate facility.

Ammonium dinitramide (AND) is one of the most promising oxidizers in propellants without chlorinated pollution to the atmosphere in these days. Potassium sulfamate (PS) is a key substance in ADN synthesis as forming nitrates such as -N(NO2)2. In this paper, potassium sulfamate as a starting material for ADN synthesis was prepared in a lab scale through crystallization with ethanol solvent, and observed the effects on the yield and purity of KDN. The prepared potassium sulfamates were analyzed using FE-SEM, XRD, BET and TGA-DSC. The lab-made PS, which was ground to 20μm showed more beneficial than a commercial product achieving high yield and purity of the synthesized KDN. It would be associated closely with crystallinity, porosity and pore size of prepared PS.