This study investigates the seismic behavior of low-aspect-ratio reinforced concrete (RC) shear walls when subjected to bi-axial lateral loading, using nonlinear finite element analysis. A three-dimensional finite element model was developed with the DIANA program and validated against previously reported experimental results. Subsequently, a parametric study was conducted by varying the wall aspect ratio of horizontal reinforcing bars under both uni-axial and bi-axial loading conditions. The analysis results show that bi-axial loading reduces shear strength by a significant amount compared to uni-axial loading, and the reduction becomes more pronounced as the aspect ratio decreases. For low-aspect-ratio walls, the influence of horizontal reinforcement on shear strength was limited, while sensitivity to bi-axial loading increased. These findings indicate that uni-axial loading–based evaluation methods may overestimate the seismic capacity of low-aspect-ratio RC shear walls.

This study conducted nonlinear static analyses to evaluate the effect of structural eccentricity on the seismic performance of piloti-type buildings. Analytical models reflecting the actual structural details of buildings acquired and operated by the Korea Land and Housing Corporation (LH) and the Seoul Housing and Communities Corporation (SH) were developed, and eccentricity ratios were considered as key analytical parameters. The effects of eccentricity on structural response were quantitatively assessed through the evaluation of performance points, plastic hinge distribution, axial load sharing ratio, and interstory drift ratio. The analytical results demonstrated that increasing eccentricity caused the performance point to approach the maximum load and concentrated plastic hinges at the ground story, leading to a noticeable degradation in overall seismic performance. Furthermore, when the eccentricity exceeded approximately 8%, the interstory drift ratio at the ground story tended to surpass the allowable limit specified in the national seismic performance evaluation guidelines. Accordingly, maintaining the eccentricity ratio below approximately 5% is suggested as a rational design strategy to ensure stable seismic performance. The findings provide valuable insights for improving seismic performance evaluation methods and design criteria for piloti-type structures.

이 연구는 라텍스 폴리머 모르타르의 경제성과 시공 효율을 개선하기 위해 산업부산물인 플라이애쉬 및 고로슬래그 미분말을 활용한 친 환경 배합 설계 도출을 위한 압축강도 및 유동성 특성을 분석하였다. 친환경 배합 설계를 위해 물-바인더 비 (W/B)를 0.5로 고정하고, 고로 슬래그 미분말을 시멘트 중량 대비 10% 치환하였다. 또한 플라이애쉬 혼입량을 시멘트 중량대비 0%부터 15%까지 5%씩 증가시키는 방식 으로 변수를 설정한다. 압축강도 및 유동성 실험은 KS L 5105에 의거하여 하였다. 압축강도 실험결과, 재령 1일 압축강도에서는 모든 산업 부산물 혼입 배합에서 초기 강도 저하가 나타났다. 그러나 재령일이 증가함에 따라 강도 회복 경향이 확인되었으며, 산업부산물이 혼입된 변수들은 재령 14일차에 20MPa를 넘는 강도를 나타내며 Latex(Control) 변수보다 44%의 높은 강도를 보였다. 이는 산업부산물의 잠재 수경 성 및 포졸란 반응에 기인한 것으로 판단된다.플로우 측정값은 192 ~ 197mm 수준으로 나타났다. 산업부산물 중 고로슬래그만 혼입된 Case 1 변수에서는 유동성이 소폭 감소하였으나, 플라이애쉬 5% 이상 혼입 시 구형 입자 효과에 의해 유동성이 회복되는 경향을 보였다. 이러한 실험 결과들을 바탕으로 고로슬래그 및 플라이애쉬를 동시혼입하여 라텍스 폴리머 모르타르의 경제성 및 시공성 효율을 개선하고 친환경적 으로 적용 가능성을 보이고 있다. 향후 내구성 및 장기 성능 평가를 통해 실용가능성을 추가 검증할 필요가 있을 것으로 판단된다.

The renewable energy has, currently, been used because of its eco-friendly energy such as no emission gas and less environmental pollution. Fuel cell electric vehicle (FCEV) using polymer electrolyte membrane fuel cell (PEMFC) uses the hydrogen as fuel to obtain the power by electrochemical reaction. The objective of this study is to investigate the flow characteristics of the hydrogen according to entrainment ratio for ejector of FCEV through comparison analysis with the air. As the results, the flow of hydrogen in ejector corresponds to turbulence with Reynold number 18,093. The pressure difference of the hydrogen between primary flow and secondary flow in ejector was about 16 times compared with that of the air. The mean velocity of the hydrogen in ejector outlet was faster about 15 times than the air.

본 연구는 중국 제조 상장기업을 대상으로 해외 매출 비중과 해외자회사 진출 국가 수가 기업의 혁신성과에 미 치는 영향을 분석하고 국가지분율(state ownership ratio)이 이들 관계에 미치는 조절효과를 실증적으로 검토 해 보고자 하였다. 이를 위해 기업의 해외시장 진출과 혁신성과 창출에 관한 기존 연구들을 기반으로 세 가지 가 설을 설정하고, 2007년부터 2022년까지 CSMAR 데이터베이스를 통해 47개 기업의 205개 관측치를 수집하여 중국 제조 상장기업의 연도별 패널데이터를 구축하였다. 랜덤 효과 포아송 회귀(random-effects Poisson regression)분석 결과, 해외 매출 비중과 해외자회사 진출 국가 수는 모두 기업의 혁신성과에 부정적인(-) 영향 을 미치는 것으로 나타났다. 또한, 국가지분율은 본 연구의 국제화 변수(해외 매출 비중, 해외자회사 진출 국가 수)와 혁신성과 간의 부정적 관계를 강화하는 조절변수로서 기능한다는 것을 발견하였다. 본 연구는 제도적 맥락 에서 국제화와 혁신성과 창출 간의 관계를 이론적으로 논의하고 이에 대한 실증분석 결과를 제시함으로써 관련 정책 입안자 및 경영자들에게 국제화 전략 수립에 관한 실무적 시사점을 제공한다.

In the present analysis study, an analysis model was developed using ANSYS Workbench to verify the dynamic characteristics of the cabinet and the vibration reduction effect of applying TMD. The analysis modeled a simplified equivalent structure of a nuclear power plant cabinet, and a method was explored to reduce the cabinet's resonant response by installing TMD on top of the cabinet. For the analysis, harmonic loads and SSE seismic waves were input to conduct modal analyses of the cabinet and TMD. The cabinet vibration reduction effect of TMD installation was investigated, as well as the time histories of displacement and acceleration. The analysis results showed that the primary mode of the cabinet had a MPMR of approximately 53.9%, significantly affecting the dynamic behavior of the cabinet compared to other modes. However, a MPMR of approximately 8.9% was also observed in higher-order modes. With TMD installed, the peak response was significantly reduced, the larger curve split into two smaller curves, and the response at the original natural frequency was reduced by up to approximately 60%. The cabinet's time response showed a decrease in displacement/acceleration vibration response as the damping ratio increased. This indicates a narrow bandwidth and peak suppression of the response envelope, and the maximum displacement and acceleration reduction effects were approximately 33.1% and 27%, respectively.

As South Korea enters a super-aged society, the number of nursing hospitals has increased rapidly, yet there are no legal staffing standards for caregivers. This absence creates a severe vulnerability regarding evacuation safety during fires. This study quantitatively analyzes evacuation times using a simulation, applying a '3:1 patient-to-caregiver ratio' based on Japanese standards. Four scenarios combining Day/Night shifts and Existing/Proposed (3:1) staffing were compared using a real hospital model. The results indicate that applying the 3:1 standard reduced the total evacuation time by 41% (1210s → 710s) during the day and 22% (1290s → 1000s) at night compared to existing staffing levels. This empirically demonstrates that the patient-to-caregiver ratio is a key variable in evacuation performance and suggests an urgent need for legal minimum staffing standards to ensure patient safety.

Rapid post-earthquake retrofit decisions require reliable estimates of interstory drift ratio. Conventional field practices either depend on instrumented measurements constrained by sparse sensor coverage or rely on qualitative expert judgment. This study aims to develop a CNN-based interstory drift ratio prediction method for reinforced concrete columns using strain-derived damage images. Reinforced concrete columns are modeled and analyzed in OpenSees to obtain strains and displacements. Strain fields are converted into strain-derived damage images through threshold-based staging that encodes discrete damage states. Structural parameters are concatenated to the damage image by adding fixed-value columns so the network can read structural context in a single two-dimensional input. We design systematic comparisons to isolate the benefit of structural information and section coverage. First, models without structural parameters are trained. Second, single-parameter variants are trained where only one attribute is provided. Third, full-parameter models include all attributes. For each setting, both single-section and multi-section inputs are evaluated. Samples are split by case and then divided 80/20 into training and validation sets. Model performance is reported using RMSE, MAE, and R-squared. The proposed approach achieves accurate inter-story drift ratio prediction overall, with improved performance when all structural parameters and multi-section inputs are used.

This study proposes a wind power generation system designed to enhance energy self-sufficiency in high-rise buildings by integrating internal and external airflow sources. In such structures, external wind generated by building height and form and internal airflow induced by the stack effect coexist but move in different directions. This study introduces a system that collects and integrates five types of wind into a single, unified flow. Wind speed data were calculated using meteorological datasets and stack effect equations, and a prototype was designed using Autodesk Fusion360. CFD simulations were conducted to determine the combined wind speed at the outlet. Based on the simulated results, expected power output was calculated using wind power equations. The building energy model was created in DesignBuilder and simulated in EnergyPlus using default office building settings. The predicted annual wind energy generation is approximately 962,022.85kWh, covering 11.73% of the building’s total annual electricity use. The study demonstrates the potential for wind-integrated high-rise designs to contribute to energy autonomy.

This study was conducted to determine the effect of water temperature during the gonadal inactive season on the sex ratio of Tegillarca granosa, a sequential hermaphroditic bivalve. The sex ratio (F:M) of the group reared in wild was 1:1.3 (n=40:52), and the female ratio was 43.5%. In experimental groups that experienced different water temperature conditions (5.0, 7.0, 9.0 and 11.0℃) in an indoor aquarium during the gonadal inactive stage, the male ratio tended to increase as the water temperature increased. The correlation between water temperature and sex ratio was calculated as R2=0.7748. The results suggest that for sequential hermaphroditic bivalves, population sizes may decrease as the proportion of females decreases if water temperatures continue to rise due to climate warming.

In this study, we performed experiments aimed at improving the performance of circular Tuned Liquid Dampers (TLDs). TLDs offer numerous advantages over other passive vibration control devices. They are easy to install not only in new structures but also in existing ones, and they provide high cost efficiency compared to Tuned Mass Dampers (TMDs). Maintenance is straightforward, requiring only checks of the liquid level and inspections for any leakage. To adjust the natural frequency of a TLD for both installation and maintenance, we can simply manage the liquid level within the device. However, much of the existing research on enhancing TLD performance has focused on rectangular shapes. Therefore, we conducted experiments to investigate ways to achieve an improved damping ratio in circular TLDs equipped with internal dampers. A large number of shaking table experiments were carried out using various configurations of TLDs with dampers. We explored different arrangements of dampers and compared their performance against that of conventional TLDs.

This study analyzes how the damping characteristics of anisotropic magnetorheological elastomers (MREs) change according to magnetic flux density, the volume fraction of carbonyl iron powder (CIP), and pre-stress. MREs are intelligent materials whose mechanical properties change depending on the magnetic field, and while research on stiffness changes has been actively conducted, analysis of damping characteristics is relatively insufficient. Consequently, the damping characteristics of MREs showed nonlinear responses depending on the interaction among magnetic flux density, CIP volume fraction, and pre-stress, confirming that damping performance can be utilized as a controllable material parameter. These results suggest the possibility that, in the design of MRE-based vibration control systems, not only stiffness but also damping characteristics can be actively controlled, and they provide basic data for the future development of high-performance vibration reduction technologies.

Atmospheric characterization has become a crucial area of study for exoplanets. The exoplanets known as ultra-hot Jupiters (UHJs) offer a natural laboratory for studying extreme atmospheric physics that cannot be observed in the solar system. One way to analyze their atmospheres is by transmission spectroscopy. However, it can be challenging to obtain such information because a planet’s signal is too weak compared to that of its host star, resulting in the planetary contribution to the observed spectrum being negligible. Therefore, the minimum observational requirements must be assessed first to distinguish the planetary signal from the stellar one to study these planets. In this context, we obtained the transmission spectra of UHJs TOI-1431 b and WASP-189 b by observing each exoplanet for one night with BOAO Echelle Spectrograph (BOES) on the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO). We searched for various chemical species by cross-correlating the exoplanetary spectra with model synthetic spectra. Our search for atmospheric signal returned a detection confidence level less than 3 σ for both targets. Therefore, we applied model injection to recover the atmospheric signals of the planets and assessed the minimum signal-to-noise ratio (S/N) to achieve 5 σ detection. During our search, we successfully recovered the planet signals with detection significances of 5.11 σ after a 750% injection of the model signal for TOI-1431 b and 5.02 σ for a 90% injection forWASP-189 b. These signal injection exercises suggest that a higher S/N of the transmission spectra is required to detect the planetary absorption features, and this can be done by stacking data from the observations of more than three cycles of the transit of a planet with a small-scale height such as WASP-189 b at BOAO facilities.

전 세계 이산화탄소 배출량이 지속적으로 증가하면서, 환경 개선 및 탄소 격리를 위한 다양한 연구들이 진행되고 있 다. 건설 산업에서도 탄소를 줄이기 위한 연구로 바이오차를 건설 자재에 사용하여, 탄소 격리를 위한 방법으로 진행되고 있다. 바이오차는 바이오매스를 열분해하여 생성한 숯으로, 높은 탄소 함량과 다공성 구조가 특징이며, 탄소 격리를 위한 물질로 떠오 르고 있다. 본 연구에서는 시멘트 사용량을 줄이고 바이오차를 혼입한 콘크리트를 건설 자재로써 가능성을 확인하고자 하였다. 이를 위해 시멘트의 일부를 바이오차로 치환하여 혼입한 콘크리트의 역학적 특성(슬럼프, 공기량, 압축강도)과 질량 기반 특성 (흡수율, 밀도, 공극률)을 평가하였다. 바이오차의 시멘트 치환율은 0%, 5%, 10%로 설정하였다. 바이오차의 수분 흡수 및 보유 력에 따라 바이오차의 시멘트 치환율이 증가할수록 슬럼프는 감소하였다. 바이오차의 다공성 구조를 SEM 실험으로 확인하였으 며, 이에 따라 콘크리트에서의 공극 형성으로 바이오차의 시멘트 치환율이 증가할수록 공기량과 흡수율이 증가하였다. 바이오차 의 시멘트 치환율 5%에서 압축강도와 비강도가 가장 높은 값으로 나타났으며, 탄소 격리를 위한 방법으로 건설 자재 활용의 가능성을 확인하였다.

Near infrared reflectance spectroscopy (NIRS) is widely used to assess the nutrient composition of forages. In forage, the leaf to stem ratio of alfalfa greatly affects its forage quality, with a high ratio of leaf indicated as high quality. This study aimed to evaluate the predictability of the alfalfa leaf-to-stem ratio and feed value using NIRS. Alfalfa hay was manually separated into leaves and stems by hand and the analysis samples were then made in the controlled range between 0 and 100%. Calibration models (n=320) were developed using modified partial least squares regression (MPLS) based on cross-validation. The optimal calibrations were selected based on the highest coefficients of determination in cross-validation (R2) and the lowest standard error of cross-validation (SECV). The prediction accuracy for the leaf-to-stem ratio (SECV, 5.95 vs. 5.71%; R2, 0.91 vs. 0.91) in alfalfa hay was comparable. For leaves, the standard error of calibration (SEC) was 4.94% (R2=0.94), and for stems, it was 4.81% (R2=0.94). The leaves and stems of the SEC were 4.94% (R2=0.94) and 4.81% (R2=0.94), respectively. The prediction accuracy for feed value, based on the leaf-to-stem ratio, predicted SECV values of 0.92% (R2=0.88) for crude protein (CP) content, 1.92% (R2=0.91) for neutral detergent fiber (NDF) content, 1.36% (R2=0.91) for total digestibility nutrient (TDN) content, and 9.86 (R2=0.81) for relative feed value (RFV). The results of this study demonstrate the potential of the NIRS method as a reliable tool for predicting the leaf-to-stem ratio of alfalfa hay, and show available techniques for routine feed value evaluation.