Environmental pollution has led to global warming, which threatens human life. In response, hydrogen is gaining attention as a next-generation energy source that does not emit carbon. Due to its explosive nature, special care must be taken in the safe storage and transportation of hydrogen. Among various storage methods, liquefied storage, which can reduce its volume to 1/800, is considered efficient. However, since its boiling point reaches -253°C, the design of an insulation system is essential. For the design of insulation systems applied to large containers, a membrane-type design is required, which necessitates the use of cryogenic adhesives. To evaluate whether the cryogenic adhesive is properly implemented, assessments such as tensile and shear tests are necessary. This study presents a methodology for shear evaluation. Conventional methods for shear evaluation of adhesives result in slippage, preventing proper assessment. Therefore, a method involving drilling holes in the gripper and pulling from the holes must be applied. Optimal design concerning the size and location of the holes is required, and this study derives optimal values based on finite element analysis. By conducting experiments based on the results of this study, it is expected that the risk of gripper damage will be minimized, allowing for accurate evaluation of the adhesive’s performance.

Advancements in technology for large aircraft have led to the development of new materials for aviation. Traditional alloy-based components in aircraft, once prevalent, are now being replaced by composite materials that offer superior performance in terms of strength and operational limits. Notably, propellers have evolved from wood to composite materials, finding application in contemporary small aircraft. In this context, there is a need for research on the composite propellers of the 3-blade "W Company," based on the widely used Rotax 914 engine in South Korea. This study aims to investigate the changes in noise and thrust corresponding to variations in propeller blade angles and engine RPM, with the goal of selecting the optimal propeller pitch angle. Particularly, the "W Company's" propellers are durable and cost-effective, widely adopted in domestic aircraft. The research seeks to propose an effective method to minimize noise while maintaining the necessary thrust, contributing to the smooth operation of aircraft and promoting coexistence with local communities.

세계적인 환경 규제로 인해 마그네슘 합금과 같은 경량 소재에 대한 수요가 증가하고 있으며, 마그네슘 합금 소재의 다양한 산업계 적용을 위한 용접 및 접합 방식에 대한 연구도 지속적으로 수행되고 있다. 앞선 Part I 연구에서는 마그네슘 합금에 대한 파이버 레이저 Bead on Plate(BOP) 실험을 수행하여 맞대기 용접 조건의 확보를 위한 기초 연구를 수행하였으며, 본 연구에서는 Part I의 기초 BOP 실험에서 도출된 적합한 레이저 출력과 용접 속도를 바탕으로 두께 3mm의 AZ31B 마그네슘 합금에 대해 맞대기 용접을 시행하였고, 인장시험 및 경도시험을 수행한 후 기계 물성 데이터를 분석하였다. 분석 결과 레이저 출력 2.0 kW, 50 mm/s (Heat input)의 조건에서 항복강도 151.5 MPa, 인장강도 224.1 Mpa으로 우수한 인장, 항복강도를 얻을 수 있었다.

In the past, aviation technology developed from wood to alloys to composite materials. Propellers have also evolved from wood to composite materials for modern small aircraft. In this context, research is needed on a three-blade composite propeller based on the Rotax 912 engine, which is widely used in Korea. In this study, the goal is to select the optimal propeller pitch angle by investigating noise changes according to changes in blade angle and engine 4000RPM of three types of three-blade propellers different from each propeller manufacturer. By comparing the noise of the three types of propellers most commonly used in Korea and suggesting the minimum noise blade angle for each propeller, we aim to help aircraft operators select propellers and resolve noise complaints around airfields.

펩타이드형 독소인 마이크로시스틴(microcystins, MCs) 과 노둘라린(nodularin, NOD)은 남조류라고도 알려진 시 아노박테리아에 의해 생성되는 2차 대사산물로, 독소에 오 염된 물, 토양 및 비료를 사용함으로써 농산물 내에 축적 되고 이를 사람이 섭취함으로써 건강상 위해가 발생할 수 있다. 최근 MCs과 NOD의 농산물 내 오염에 대한 관심 이 대두되며 국내외에서 여러 분석법을 기반으로 농산물 내 오염 수준을 조사하고 있다. 하지만 아직까지 수행된 연구가 많지 않으며, 특히 펩타이드형 독소 중 MCs의 분 석 연구에 치중되어 있거나 오염 취약 지역에서 재배한 농산물이 주로 오염도 조사에 사용되는 등 연구에 한계가 있으므로 MCs과 NOD의 관리를 위해서는 보다 많은 체 계적인 연구가 필요할 것으로 생각된다. 본 연구에서는 체 계적인 모니터링 및 안전관리의 기반을 마련하기 위해 MCs 및 NOD의 이화학적 특성, 독성, 분석법, 오염사례 및 관리현황에 대해 기술하였다.

모기류는 흡혈을 통해 원충, 바이러스, 사상충 등 다양한 병원체를 보유하며 말라리아, 일본뇌염, 웨스트나일열, 뎅기열 등을 사람에게 매 개하는 위해성이 있는 위생해충이다. 이번 연구에서는 해외유입 모기류 감시를 위해 경상남도 고성군에 스마트 고공포집기를 설치하여 2022년 부터 2023년까지 모기류들을 모니터링하였다. 조사기간 동안, 총 3속 5종 43개체가 채집되었으며, 이중 삼일열말라리아를 매개하는 벨렌얼룩날 개모기(Anopheles belenrae)를 경남 지역에서 처음으로 발생함을 확인하였다. 본 연구에서는 스마트 고공포집기를 통해 해외에서 유입가능한 모 기류에 대한 실시간 모니터링이 가능함을 확인하였다.

급속한 사회 변화로 인한 저출산 및 경력단절, 일-가정 갈등, 가족해체 등의 복합적인 어려움에 직면한 기혼 직장여성은 소 외와 우울, 가족기능 약화, 삶의 질 악화로 강하게 표출되고 있 으며, 가족 건강성 회복을 통해 삶의 질 개선에 직접적인 영향 관계를 지적한 선행연구는 다수 발견할 수 있었으며, 가족 건 강성에 대한 다차원적 접근과 심리적 웰빙과의 관계를 밝히는 실증적인 연구가 필요하였다. 이 연구는 가족 건강성이 기혼 직장여성의 심리적 웰빙에 미 치는 영향 관계를 분석하고 가족 건강성과 심리적 웰빙 증진 방안을 제시하여 가족 건강성 회복을 위한 다차원적 접근 방안 제시에 기여함을 목적으로 한다. 수도권 지역의 기혼 직장여성을 대상으로 한 실증분석 결과, 가족 건강성 하위 요인인 가족 간의 의사소통 및 유대감, 가치 체계 공유, 문제해결 능력이 향상될수록 심리적 웰빙 수준은 향상되는 것으로 나타났고, 그 분석 결과를 제시하였다. 시사점은 다음과 같다. 첫째, 가족 건강성에 대한 하위 요인 의 다차원적 분석을 실시하였는 바, 의사소통, 유대감, 가치체 계 공유, 문제해결 능력의 경우 통계적으로 유의미하였으며, 기 혼 직장여성의 심리적 웰빙을 향상시키기 위한 다차원적 접근 의 필요성 제기 및 기초자료로의 활용이 가능하다. 둘째, 인구사회학적 특성에 따라 심리적 웰빙에 미치는 정도 의 차이가 있는 것으로 나타났는 바, 연령, 학력, 종교, 가정 수 입, 취업 동기, 직장 유형 등의 기혼 직장여성에 개인별 맞춤형 의 지역 내 네트워크 강화와 사회교육 프로그램 개발, 참여 유 도를 위한 인센티브 제공 등의 확대가 무엇보다도 중요하다.

본 연구는 경남지역의 대나무 숲(솜대 및 왕대)에 대한 입목밀도, 신죽 발생량 및 고사량 등을 추정하기 위하여 수행되었다. 입목밀도와 신죽 발생량 분석을 위한 표준지 수는 299개소 였으며, 고사량 분석을 위한 표준지 수는 255개소 였다. 분석을 위한 추정식은 역다항식, 지수식, 비선형식, 회귀식 등을 다양하게 적용하였으며, 이들의 검정은 적합도지수를 이용하였고, 잔차 검정을 실시하였다. 신죽의 발생량 추정식은 1차 역다항식이 최적인 것으로 나타났으며, 적합도 지수는 0.2622로 나타났다. 현존 입목죽 추정을 위한 최적식은 지수함수식이었으며, 적합도 지수는 0.1963으로 낮게 나타났다. 그리고 고사량 추정식은 현존 입목죽 본수와 신죽 본수를 설명변수로 하는 회귀식으로 도출되었으며, 결정계수는 0.4996인 것으로 나타났다. 이들 식을 경남지역으로 확산시키면, 경남지역 대나무 숲의 연간 평균 입목밀도는 19,309본/ha, 고사량은 1,706본/ha이 될 것으로 추정되었 다. 신죽 발생량 및 현존 입목죽 발생량 추정식의 적합도가 모두 낮게 나타난 것은 현재 관리되지 않는 대나무 숲의 현 상황을 그대로 보여 주는 결과라 생각된다. 그러나 이들 두가지 추정식에 대한 잔차검정에서 일부 구간을 제외하고는 “0”를 중심으로 잔차가 고르게 분포하여 식을 이용함은 가능할 것으로 보였다. 다만 추후 정밀한 현장조사와 모니터링 및 현실을 반영할 수 있는 적합성 높은 식의 도출이 요구된다.

PURPOSES : The tire-pavement interaction noise (TPIN) comprises four sources, among which the tire tread vibration noise (TTVN) and air pumping noise (APN) are known to be the most influential. However, when evaluating TPIN, the noise level is estimated based on the overall noise, because general noise measurement methods cannot separate TTVN and APN. Therefore, this study aims to develop a method to separate TTVN and APN in TPIN for quantitative assessment of pavement noise. METHODS : Based on the results of our literature review and frequency band noise data measured in our study, we identified the dominant frequency ranges for TTVN and APN. Additionally, we evaluated TTVN and APN across various pavement types. RESULTS : TTVN was found to be dominant in frequency bands below 800 Hz, while APN was dominant in frequency bands above 800 Hz. Additionally, regardless of the vehicle type, vehicle speed, or pavement type, APN exhibited higher levels compared to TTVN. This result shows that APN has a more significant impact on TPIN than TTVN. CONCLUSIONS : The separation method of TTVN and APN proposed in this study can be utilized to quantitatively assess the relationship between the primary noise sources in TPIN and the characteristics of pavement texture in future research. Furthermore, it is anticipated that characteristics of low TPIN and optimal texture conditions can be proposed to mitigate TPIN, thus contributing to the development of lownoise pavements.

PURPOSES : Recently, air pollution due to fine particulate matter has been increasing in Korea. Nitrogen oxides (NOx) are particulate matter precursors significantly contributing to air pollution. Increasing efforts have been dedicated to NOx removal from air, since it is particularly harmful. Application of titanium dioxide (TiO2) for concrete road structures is a suitable alternative to remove NOx. As the photocatalytic reaction of TiO2 is the mechanism that eliminates NOx, the ultraviolet rays in sunlight and TiO2 in existing concrete structures need to be contacted for the reaction process. For the application of vertical concrete road structures such as retaining walls, side ditches, and barriers, a pressurized TiO2 fixation method has been developed considering the pressure and pressurization time. In this study, longterm serviceability and repeatability were investigated on concrete specimens applying the dynamic pressurized TiO2 fixation method. Additionally, the environmental hazards of nitrate adsorbed on TiO2 particles were evaluated. METHODS : Concrete specimens to simulate roadside vertical concrete structures were manufactured and used to evaluate the long-term serviceability and repeatability of the dynamic pressurized TiO2 fixation method. The NOx removal efficiency was measured using NOx evaluation equipment based on ISO 22197-1. In addition, the nitrate concentration was measured using a comprehensive water quality analyzer for evaluating environmental hazards. RESULTS : As the experiment to evaluate the NOx removal efficiency of the dynamic pressurized TiO2 fixation method progressed from one to seven cycles, the nitrate concentration increased from 2.35 mg/L to 3.06 mg/L, and the NOx removal efficiency decreased from 53% to 25%. After seven cycles of NOx removal efficiency evaluation, the average nitrate concentration was 3.06 mg/L. The nitrate concentration collected immediately after the NOx removal efficiency test for each cycle was in the range of 2.51 to 2.57 mg/L. By contrast, it was confirmed that the nitrate concentration was lowered to approximately 2.1 mg/L when the surface was washed with water. CONCLUSIONS : The NOx removal efficiency was maintained at over 25% even after seven cycles of NOx removal efficiency evaluation, securing long-term serviceability. In addition, the harmful effects on the environment and human health are insignificant, since the nitrate concentration was less than 10 mg/L, in accordance with domestic and foreign standards. Practical applicability of the pressurized TiO2 fixation method was established by evaluating the long-term serviceability, repeatability, and environmental hazards.

이 연구에서는 예비 초등교사들이 금융교육을 통해 무엇을 배우고 싶어하는지를 금융교육 수요로 정의하고, 24개 금융교육 내용 요소에 대한 수요를 조사하였다. 금융교육에 대한 수요가 가장 높은 내용 요소는 ‘저축에 영향을 주는 요인’, ‘예산과 예산관리’, ‘고령사회와 연금’이었으며, 수요가 가장 낮은 내용 요소는 ‘지불 수단’, ‘소득의 결정 원인’, ‘저축의 경 제적 의의’였다. 금융교육에 대한 수요에 나이, 성별, 금융이해력 등이 미치는 영향은 없었 으며, 금융교육의 필요성에 대한 인식만 통계적으로 유의한 영향을 미쳤다. 본 연구는 예비 초등교사인 교육대학 재학생, 특히 신입생을 주요 대상으로 하였기 때문에 보다 다양한 연 령 및 집단을 대상으로 한 후속 연구의 필요성이 제안되었다.

The cultural heritage of fortresses is often exposed to external elements, leading to significant damage from stone weathering and natural disasters. However, due to the nature of cultural heritage, dismantling and restoration are often impractical. Therefore, the stability of fortress cultural heritage was evaluated through non-destructive testing. The durability of masonry cultural heritages is greatly influenced by the physical characteristics of the back-fille material. Dynamic characteristics were assessed, and endoscopy was used to inspect internal fillings. Additionally, a finite element analysis model was developed considering the surrounding ground through elastic wave exploration. The analysis showed that the loss of internal fillings in the target cultural heritage site could lead to further deformation in the future, emphasizing the need for careful observation.

This study aims to investigate the seismic response of a large span thin shell structures and assess their displacement under seismic loads. The study employs finite element analysis to model a thin shell structure subjected to seismic excitation. The analysis includes eigenvalue analysis and time history analysis to evaluate the natural frequencies and displacement response of the structure under seismic loads. The findings show that the seismic response of the large span thin shell structure is highly dependent on the frequency content of the seismic excitation. The eigenvalue analysis reveals that the tenth mode of vibration of the structure corresponds to a large-span mode. The time history analysis further demonstrates, with 5% damping, that the displacement response of the structure at the critical node number 4920 increases with increasing seismic intensity, reaching a maximum displacement of 49.87mm at 3.615 seconds. Nevertheless, the maximum displacement is well below the allowable limit of the thin shell. The results of this study provide insight into the behaviour of complex large span thin shell structures as elevated foundations for buildings under seismic excitation, based on the displacement contours on different modes of eigenvalues. The findings suggest that the displacement response of the structure is significant for this new application of thin shell, and it is recommended to enhance the critical displacement area in the next design phase to align with the findings of this study to resist the seismic impact.

In this study, the SBC system, a new mechanical joint method, was developed to improve the constructability of precast concrete (PC) beam-column connections. The reliability of the finite element analysis model was verified through the comparison of experimental results and FEM analysis results. Recently, the intermediate moment frame, a seismic force resistance system, has served as a ramen structure that resists seismic force through beams and columns and has few load-bearing walls, so it is increasingly being applied to PC warehouses and PC factories with high loads and long spans. However, looking at the existing PC beam-column anchorage details, the wire, strand, and lower main bar are overlapped with the anchorage rebar at the end, so they do not satisfy the joint and anchorage requirements for reinforcing bars (KDS 41 17 00 9.3). Therefore, a mechanical joint method (SBC) was developed to meet the relevant standards and improve constructability. Tensile and bending experiments were conducted to examine structural performance, and a finite element analysis model was created. The load-displacement curve and failure pattern confirmed that both the experimental and analysis results were similar, and it was verified that a reliable finite element analysis model was built. In addition, bending tests showed that the larger the thickness of the bolt joint surface of the SBC, the better its structural performance. It was also determined that the system could improve energy dissipation ability and ductility through buckling and yielding occurring in the SBC.

Fish resource surveys were conducted near Jeju Island in June, August and October 2021 using an underwater camera monitoring system, fish pots, and SCUBA diving methods. The efficiency of the methods used to survey fish resources was compared using the number of individuals compared to area per unit time (inds/m3/h) and the number of species compared to area per unit time (spp./m3/h). As a result of comparing the number of individuals compared to the area per unit time (inds/m3/h), the order was underwater camera 214.69, SCUBA diving 124.62, and fish pots 0.57 inds/m3/h. The number of species compared to area per unit time (spp./m3/h) is in the following order: SCUBA diving 0.85, underwater camera 0.38, and fish pots 0.01 spp./m3/h. The fish resource monitoring method using underwater cameras was found to be more efficient in individual counts, and the SCUBA diving method was found to be more efficient in species counts. When considering cost and survey efficiency, the fish resource survey method using underwater cameras was judged to be more effective. The results of this study are expected to be widely used in estimating the population density of fish, which is the core of future fisheries resource surveys.