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.

Fire emergencies in complex buildings present significant challenges to occupants, requiring rapid decision-making and efficient evacuation. This study examines the impact of fire location awareness on evacuation behavior, with fear and anxiety as mediating variables. A survey was conducted with 309 participants who had experience using multi-story buildings, and structural equation modeling (SEM) was employed to analyze the relationships among fire location awareness, fear and anxiety, and evacuation behavior. The results indicate that lower fire location awareness significantly increases fear and anxiety (β = -0.81, p < .001), while higher levels of fear and anxiety are associated with increased evacuation behavior (β = 0.496, p < .001). Furthermore, fire location awareness has a direct negative effect on evacuation behavior (β = -0.282, p < .01) while also exerting an indirect influence through fear and anxiety (β = 0.402, p < .001), confirming a partial mediation effect. These findings suggest that occupants who are unable to accurately perceive the fire’s location experience heightened levels of fear and anxiety, which may in turn excessively drive their evacuation behavior. Based on these findings, this study highlights the necessity of improving fire location awareness through enhanced alarm systems, real-time notifications, and preemptive evacuation training. Additionally, psychological preparedness programs should be introduced to regulate fear and anxiety, preventing excessive panic that may lead to inefficient evacuation behavior. Future research should explore experimental methodologies and real-life evacuation scenarios to further validate these relationships and develop optimal fire safety measures.

Runoff inhibitors can be used to suppress soil erosion and nutrient runoff. Their impact on soil ecosystems needs to be assessed. Thus, the purpose of this study was to investigate effects of runoff inhibitors on metabolic activities of soil microbes using starch, cationic starch, guar gum, xanthan gum, and PAM (polyacrylamide) as carbon sources. Responses of soil microbes to carbon sources were analyzed using Biolog EcoPlate. Soil was treated with each carbon source at 0.1, 0.5, and 1.0%. Carbon utilization was measured every week for three weeks. Average well color development (AWCD) was increased in the group treated with starch at 0.5 or 1.0% at 3 weeks after treatment. Effect of cationic starch was different depending on treatment period. This effect decreased at 3 weeks after treatment. Guar gum increased AWCD at all concentrations. Reactions of microbes were different depending on the type of carbon source. Xanthan gum increased AWCD at all concentrations, although amino acid decomposition showed no significant difference. On the other hand, PAM decreased AWCD at all concentrations. The Shannon H index representing functional diversity showed a tendency similar to that of AWCD for all treatments. These results indicate that soil treatments can have secondary effects on metabolic function of soil microbes and physical properties of soil.

본 연구는 제주시와 서귀포시에 분포하고 있는 22개 오름의 식물상 자료를 활용하여 식물 생육형별 종풍부도에 대한 경관(오름 면적, 오름 높이, 오름 임상 다양성, 500m 내 녹지 면적) 및 환경인자(기후인자, 토양인자)의 영향을 구명하기 위해 수행되었다. 22개의 오름에서 총 153과, 486속, 870종의 식물이 관찰되었으며, 각 오름 내 종수를 활용하여 생육형별 종풍부도를 산출하였다. 식물의 생육형별 종풍부도의 제어인자를 추출하기 위해, 다모형추론법과 일반최소자승법을 수행했다. 그 결과, 오름 내 식물의 종풍부도를 제어하는 주요인자는 오름 면적, 높이 및 임상 다양성과 기후인자로 나타났다. 반면, 경관적 연결성을 대변하는 오름으로부터 500m 내 녹지의 면적과 토양인자는 종풍부도에 영향을 미치지 않는 것으로 나타났다. 종-면적 관계 이론에 기반한 면적효과와 서식지 이질성 효과의 증가는 균등한 자원분배와 다양한 서식지 유형을 야기하여 식물의 종풍부도를 증가시키는 것으로 보인다. 연평균 기온 감소와 강수량 증가는 식물의 수분스트레스를 감소시켜 종풍부도에 긍정적인 영향을 미치는 것으로 나타났다. 더욱이 기온 및 강수량에 따른 강한 환경 여과 효과는 이러한 기후조건에 간접적인 영향을 받는 토양인자와 분산 여과 효과정도를 대변하는 500m 내 녹지 면적의 효과를 상쇄시키는 것으로 나타났다. 이러한 결과는 면적이 작고 서식지 유형이 단순한 오름은 종의 멸종과 개체수 감소에 대한 민감도가 높다는 것을 의미한다. 이에 따라 본 연구는 오름 내 서식지 이질성을 높이거나 환경에 적합한 식물종을 도입하는 등 경관 및 환경인자를 고려한 구체적인 관리전략이 도입되어야 함을 시사한다.

이수식 쉴드 TBM 공법에서 발생하는 부산물인 필터케이크를 유동성 채움재로의 재활용 가능성을 평가하기 위해 다양한 기초 실험을 수행하였다. 필터케이크를 굵은골재 및 잔골재와 혼합하여, 필터케이크의 함량 비율을 증가시키면서 세 가 지 배합(Case 1, Case 2, Case 3)을 구성하였다. 강도 발현을 위한 바인더로는 보통 포틀랜드 시멘트를 사용하였으며, 물- 시멘트비(w/c)를 변화시켜 플로우 시험, 블리딩 시험, 압축강도 시험을 통해 유동성 채움재로서의 가능성을 평가하였다. 시험 결과, 필터케이크 함량이 증가할수록 혼합물의 유동성은 저하되었으며, 이를 보완하기 위해 혼합수의 양을 증가시 키며 적정한 범위의 유동성을 확보하도록 하였으나, 혼합수의 양이 많아질수록 압축강도가 크게 감소하는 경향을 보였 다. 특히, 필터케이크 함량이 가장 높은 Case 3에서는 이러한 현상이 두드러지게 나타났으며, 반면 필터케이크 함량이 적 은 Case 1에서는 상대적으로 높은 강도가 발현되었다. 또한, 필터케이크 함량이 적을수록 혼합물의 유동성은 혼합수량에 민감하게 변화하였다. 블리딩은 필터케이크의 혼합 비율에 영향을 받았으며, 필터케이크 함량이 가장 높은 Case 3에서 블리딩이 가장 적게 발생하였다. 이는 필터케이크의 높은 수분 흡수율이 블리딩 감소에 영향을 미친 것으로 판단된다. 즉, 유동성, 강도, 블리딩 사이의 균형을 맞추기 위한 적절한 배합비 설정을 통해 TBM 공법 부산물인 필터케이크는 유 동성 채움재로 재활용 가능성이 높을 것으로 평가하였다.

본 연구는 스트론튬 이온(Sr²⁺) 처리가 수화 시멘트 복합체의 공극분포 특성에 미치는 영향을 실험적으로 평가하였다. 물- 시멘트비(w/c) 0.3, 0.4, 0.5로 제조된 시멘트 페이스트 시편을 21일간 탈 이온수에서 수중 양생한 후, 각각 두 개의 그룹 으로 나누었다. 첫 번째 그룹은 탈 이온수에서 추가로 7일간 양생하였고, 두 번째 그룹은 30% 질산스트론튬(Sr(NO3)2) 수 용액에서 동일기간 동안 추가 양생하였다. 양생기간 및 조건에 따른 각 시편에 대하여 수은압입법(MIP: Mercury Intrusion Porosimetry)을 사용하여 공극률 및 공극 크기 분포를 분석하였다. 실험 결과, 물-시멘트비가 낮을수록 공극률이 감소하는 것을 확인하였다. 21일과 28일간 탈 이온수에서 양생한 시편 간에는 공극률 차이가 유의미하지 않았으나, 21일 수중양생 후 스트론튬 이온에 7일간 처리된 시편은 공극률이 유의미하게 감소한 것으로 분석되었다. 특히, 물-시멘트비 0.3인 경우 에는 공극률이 33% 이상 감소하는 결과를 보였다. 또한, 공극 크기 분포 특성 분석 결과, 모든 물-시멘트비 조건에서 21 일 양생된 시편에 비해 7일간 추가 양생된 시편은 큰 공극의 양이 줄어들면서 작은 공극의 양이 증가하는 경향을 확인 하였다. 특히, 스트론튬 이온에 처리된 시편의 경우 50nm 이하의 매우 작은 공극의 양이 크게 증가하였다. 이로써 스트 론튬 이온 처리에 의해 수화 시멘트 복합체의 미세조직이 치밀해짐을 확인하였으며, SEM 분석을 통해 이러한 결과를 시 각적으로 확인하였다. 본 연구는 스트론튬 이온을 활용한 시멘트 콘크리트 표면처리 기법이 노후 시멘트 콘크리트 구조 물에 대하여 수분 침투 저항성을 향상시키는 유지관리 기술로서 잠재력을 지니고 있음을 보여준다.

제지 공정 과정에서 슬러지를 소각할 때 생성되는 제지애쉬를 도로 하부 동공 보수 재료인 유동성 채움재의 재료로 재 활용 가능성에 대하여 실험적으로 평가하였다. 유동성 채움재는 플로우 값으로 대표되는 유동성, 압축강도 및 블리딩률 에 의해 평가됨에 따라 해당 특성에 대하여 시험 및 평가를 진행하였다. 제지애쉬의 화학적 성분이 강도 발현을 위한 시 멘트와 유사한 점에 기반하여 제지애쉬를 시멘트 중량비의 0~40% 범위에서 치환하여 페이스트 혼합물을 제작하였다. 이 후, 플로우 및 압축강도 시험을 수행하여 제지애쉬의 적정 치환 범위를 선정하였다. 이후, 시멘트-제지애쉬 페이스트 혼 합물에 잔골재 및 굵은 골재를 혼합하여 유동성 채움재(CLSM: Controlled Low Strength Material) 혼합물을 배합하고 플로 우, 압축강도, 블리딩 시험을 실시하였다. 시험 결과 제지애쉬 치환율이 증가함에 따라 혼합물의 유동성 및 압축강도가 감소하였으며, 이는 제지애쉬의 높은 수분 흡수율에 의한 영향으로 판단된다. 혼합물의 적정 배합을 통하여 소정의 플로 우, 압축강도 및 블리딩률 기준을 만족할 수 있었으며, 이를 통해 제지애쉬의 유동성 채움재 활용 가능성을 확인하였다.

PURPOSES : This study aims to provide quantitative profile values for the objective evaluation of concrete surface profile (CSP) grades in concrete structures. The main aims are to quantify the CSP grade required for concrete surface pretreatment and proposing a more suitable CSP grade for structural maintenance. METHODS : Initially, the challenges in measuring concrete surface profiles were outlined by analyzing pretreatment work and profile samples of concrete pavements. Theoretical foundations for quantifying concrete surface roughness were established, and regression models including linear regression, cubic regression, and log regression were selected. Additionally, the interquartile range anomaly removal technique was employed to preprocess the data for regression modeling. RESULTS : Concrete CSP profiles were measured through indoor tests, and the measured data were quantified. Linear regression, cubic regression, and log regression models were applied to each CSP grade for comparative analysis of the results. Furthermore, comparative studies were conducted through adhesion strength tests based on the CSP grade. CONCLUSIONS : Our results are expected to establish objective standards for the pretreatment stage of concrete repair and reinforcement. The derived reference values can inform standards for the restoration and reinforcement of concrete structures, thereby contributing to performance improvement. Moreover, our results may serve as primary data for the repair and reinforcement of various concrete structures such as airports, bridges, highways, and buildings.

최근 프리팹 부재간 비간섭 계면이음 설계기술이 도입되고 기계주입식 충진 기술의 실용화 성공으 로, 교량 프리캐스트 바닥판 시공의 저해요인이 상당히 해결될 수 있다. 이 때 프리팹 부재에 GFRP 보강근을 적용한다면 가공조립비 절감 효과가 있고, 프리팹 부재의 경량화로 경제성이 제고될 뿐 만 아니라, 현장 안전성과 작업편의성이 향상될 것으로 보인다. 기존 철근 연신율은 20% 내외 수준인데 반해 GFRP 보강근의 파괴변형율은 3% 내외이며 탄성계수는 50GPa (강재 대비 25%수준)이므로, 이 러한 재료특성 차이로 인한 휨성능에 대한 영향 평가가 필요하다. 특히 GFRP 보강근을 프리캐스트 바닥판과 거더 간 계면이음 적용에 따른 영향을 평가하기 위한 프로토타입 거더를 설계하고, 재료간 계면의 부착 특성을 고려한 유한요소해석 모델을 수립하고 극한 휨성능과 소요 계면 전단성능과의 상 관관계를 검토하였다. 추후 본 변수해석 연구에 대해 실험적 검증이 완수된다면, GFRP 보강근 설계기 술을 정립하는 데 기여할 것으로 기대된다.

PURPOSES : The purpose of this study is to statistically analyze the meteorological factors that contribute to the formation of road surface icing based on actual cases of icing accidents and provide directions for improving icing evaluation criteria. METHODS : In this study, we collected cases of domestic road icing accidents by searching news articles with the keyword ‘icing collision accidents’. Subsequently, we determined the latitude, longitude, and altitude of accident locations using satellite map service. We applied the Inverse Distance Weighting (IDW) method and temperature lapse rate to estimate meteorological data at each location. Finally, statistical analysis was conducted for temperature, humidity, and precipitation occurrence using probability density functions. RESULTS : As a result, road icing accident data points with identifiable location coordinates were collected. Among these, temperature, humidity, and precipitation occurrence from Automated Weather Stations (AWS) data were selected for analysis. During the process of correcting meteorological factors using the Inverse Distance Weighting (IDW) method, the optimal Weighting Exponent (p) that minimizes the error was determined and applied. The results showed that accidents occurring in the morning indicated the highest accident occurrence rate. The average temperature at the time of the accidents was -1.4°C, with a humidity level of 85.1%. Precipitation was observed at the time of the accident in 19 cases. CONCLUSIONS : Icing on pavement can occur not only under extreme weather conditions but also under typical meteorological conditions. Typically, icing can occur when the relative humidity is above 70%. Accordingly, for future improvements in the evaluation criteria for icing-prone areas by the Ministry of Land, Infrastructure and Transport, it is possible to incorporate the temperature and humidity ranges that generally lead to icing, taking into account climate characteristics.

In this study, the structural integrity of the composite rocket motor case of a space launch vehicle was evaluated by conducting compression and bending tests. Two composite rocket motor case specimens with different stacking patterns were prepared for each test, and a dedicated jig was designed and manufactured. The test procedure was developed and applied separately for compression and bending tests. By performing these tests, the composite rocket motor case structural safety was assessed.

Cellular myxoma is an uncommon type of myxoid benign tumor, predominantly occurring in adult female patients aged >40 years. This report aims to document a case of cellular myxoma that occurred in the buccal mucosa. Compared to intramuscular myxomas, cellular myxoma demonstrates hypercellularity and vascularity. Its manifestation in the soft tissue of the head and neck area is exceptionally rare. Generally, cellular myxoma manifests as a firm and immovable mass covered with normal oral mucosa, with no associated clinical symptoms. Homogenous low signal intensity on T1-weighted scans and high-signal intensity on T2-weighted magnetic resonance scans reveal cellular myxoma, as most lesions show well-defined margins and heterogeneous contrast enhancement. The significant histologic features include a focal or diffuse increase in cellularity with fibroblast-like cells and vascularity with an abundant collagenous matrix. Our presented case reflects these facts examinations, based on which a final diagnosis of cellular myxoma was made. Immunohistochemistry revealed locally and diffusely positive SMA and CD34. The clinical tendency of cellular myxoma with hypercellularity may affect the production of myxoid and collagenous substrates, and if complete resection is not performed, the possibility of local recurrence in the primarily affected region remains. Hence, complete surgical excision was performed under general anesthesia, and follow-up until a year after treatment revealed no observed recurrence. To achieve precise diagnosis and complete treatment without local recurrence, several diagnostic examinations should be considered.

Numerous studies have attempted to predict the energy output of solar-powered vehicles based on different parameters such as road conditions, driver characteristics, and weather. However, since these studies were conducted on stationary vehicles, they are limited in their accuracy when applied to driving vehicles. This study aimed to improve the accuracy of electric power prediction for a solar-powered bus by applying a technique that improves energy efficiency without affecting driving performance. A comparative analysis of power generation and solar irradiance data was conducted for the bus driven on different roads to forecast its power generation, and a high-accuracy power generation prediction equation was derived. A comparison with actual test results revealed that a power generation forecast accuracy of at least 90% was achieved, validating the equation used for forecasting. With this power generation prediction process, it is possible to forecast the amount of energy generated in advance when a solar bus is operated in a specific area.

We used the measurement data derived from a proton transfer reaction time-offlight mass spectrometry (PTR-ToF-MS) to ascertain the source profile of volatile organic compounds (VOCs) from 4 major industrial classifications which showed the highest emissions from a total of 26 industrial classifications of A industrial complex. Methanol (MOH) was indicated as the highest VOC in the industrial classification of fabricated metal manufacture, and it was followed by dichloromethane (DM), ethanol (EN) and acetaldehyde (AAE). In the industrial classification of printing and recording media, the emission of ethylacetate (EA) and toluene (TOL) were the highest, and were followed by acetone (ACT), ethanol (EN) and acetic acid (AA). TOL, MOH, 2-butanol (MEK) and AAE were measured at high concentrations in the classification of rubber and plastic manufacture. In the classification of sewage, wastewater and manure treatment, TOL was the highest, and it was followed by MOH, H2S, and ethylbenzene (EBZ). In future studies, the source profiles for various industrial classifications which can provide scientific evidence must be completed, and then specified mitigation plans of VOCs for each industrial classification should be established.

13세기부터 15세기까지 양식적 변화와 이를 설명하는 미술에 대한 문헌들은 공방의 협 업에서 미술가 개인에 대한 관심으로 변화되고 있는 상황을 반영한다. 교회 미술처럼 장소와 미술품이 밀접한 관계를 지닐 때, 공방의 작업과 미술가 개인의 작업은 다르다는 점에서 표 현에 대한 접근 방식도 변화되었다. 이런 점은 공방의 문화를 다루었던 첸니노 첸니니와 미 술의 원리를 다루며 개인의 선택으로서 표현을 다루는 알베르티의 색채에 대한 접근 방식을 통해서 확인할 수 있다. 첸니니는 원색에 흰색을 추가해서 명암을 표현했다면, 알베르티는 검정-원색-흰색을 통해 명암을 표현한다. 장소를 매개로 공간 속에서 미술가의 표현을 조절 해야 하는 공방의 입장은 미술가 개인의 역량을 드러내기 위해 새로운 시도를 진행하고자 하는 입장과 다르기 때문이다. 미술품과 장소의 관계는 15세기 이후 이론이 미술에 대한 담 론을 주도하는 경우에도 새로운 이질적 표현을 살펴볼 수 있다는 점도 확인할 수 있다. 이 시기 교회 미술의 사례를 살펴보는 과정에서 장소와 미술품의 관계는 양식의 변화를 이해하 는 데 중요한 요인이며, 동시에 이론에 바탕을 둔 이론적 관점에서 벗어나는 새로운 시도를 이해하는 데 도움이 된다.

‘Tracers’ are bullets that emit light at the backside so that the shooter can see the trajectory of their flight. These light-emitting bullets allow snipers to hit targets faster and more accurately. Conventional tracers are all combustion type which use the heat generated upon ignition. However, the conventional tracer has a fire risk at the impact site due to the residual flame and has a by-product that can contaminate the inside of the gun and lead to firearm failure. To resolve these problems, it is necessary to develop non-combustion-type tracers that can convert heat to luminance, so-called ‘thermoluminescence (TL)’. Here, we highly improve the thermoluminescence properties of MgB4O7 through co-doping of Dy3++Ce3+ and Dy3++Na+. The presence of doping materials (Dy3+, Ce3+, Na+) was confirmed by XPS (X-ray photoelectron spectroscopy). The as-synthesized co-doped MgB4O7 was irradiated with a specific radiation dose and heated to 500 °C under dark conditions. Different thermoluminescence characteristics were exhibited depending on the type or amounts of doping elements, and the highest luminance of 370 cd/m2 was obtained when Dy 10 % and Na 5 % were co-doped.

To provide information needed for managing fish resources and protecting the ecosystem of Cheonsu Bay, bimonthly variations in species composition and abundance of fish eggs and larvae were investigated. The samples were collected by using bongo net at three different stations from February 2020 to December 2021. Fish eggs were divided into Engrualis japonicus and unidentified eggs, of which Engragulis japonicus accounted for 85.6% of the total eggs collected. A total of 21 species representing 17 families and 6 orders were collected. The three dominant species were Gobiidae spp, Thryssa hamiltonii and E. japonicus and these three species accounted for 74.1% in the total number of individuals. The number of species was highest in August, 2020 and lowest in February, 2020 and 2021; the number of individuals was highest in August, 2020 and lowest in February, 2020. Temporal changes in the abundances of pelagic eggs and larval fishes corresponded with temperature.

The recycling of solid waste materials to fabricate carbon-based electrode materials is of great interest for low-cost green supercapacitors. In this study, porous carbon foam (PCF) was prepared from waste floral foam (WFF) as an electrode material for supercapacitors. WFF was directly carbonized at various temperatures of 600, 800, and 1,000 oC under an inert atmosphere. The WFF-derived PCF (C-WFF) was found to have a specific surface area of 458.99 m2/g with multi-modal pore structures. The supercapacitive behavior of the prepared C-WFF was evaluated using a three-electrode system in a 6 M KOH aqueous electrolyte. As a result, the prepared C-WFF as an active material showed a high specific capacitance of 206 F/g at 1 A/g, a rate capability of 36.4 % at 20 A/g, a specific power density of 2,500 W/kg at an energy density of 2.68 Wh/kg, and a cycle stability of 99.96 % at 20 A/g after 10,000 cycles. These results indicate that the C-WFF prepared from WFF could be a promising candidate as an electrode material for high-performance green supercapacitors.