• Journal of Platform Technology
• /
• 제9권3호
• /
• pp.36-43
• /
• 2021

뇌졸중 질환은 전세계적으로 가장 중요한 사망원인 중 하나이며, 특히 고령자에게 장애의 원인이 되는 가장 중요한 질환이다. 뇌졸중 질환이 발생하면 사망 또는 심각한 장애를 유발하기 때문에, 적극적인 일차 예방과 전조증상의 빠른 발견이 매우 중요하다. 특히, 일상생활에서의 뇌졸중 전조증상 발병을 감지 및 정확히 예측하여 전문가의 신속한 진단을 유도할 수 있어야 한다. 최근까지의 연구에서는 뇌졸중 환자의 전조증상을 예측하는 방법론으로 CT(Computed Tomography)나 MRI(Magnetic Resonance Imaging)와 같은 영상 분석이 대부분이었으나, 이러한 접근에는 오랜 검사 시간과 높은 검사 비용 등에 대한 한계점을 가지고 있다. 본 논문에서는 고령자의 뇌졸중 질환 발병이 보행 시 족압(Foot Pressure)에 어떤 영향을 미치는지 임상 데이터를 이용해 실험하였다. 실험 결과, 보행 중에 뇌졸중 고령자와 일반 고령자 간에 12개의 셀에서 * p < .05 인 유의미한 차가 있음을 분석 및 검증하였다. 결과적으로 고령의 뇌졸중 환자와 일반 고령자의 일상생활의 보행 패턴에 유의미한 차이를 발견했다는 것에 그 의미가 크다고 할 수 있다.

• Molecules and Cells
• /
• 제44권2호
• /
• pp.79-87
• /
• 2021

Chromatin dynamics is essential for maintaining genomic integrity and regulating gene expression. Conserved bromodomain-containing AAA+ ATPases play important roles in nucleosome organization as histone chaperones. Recently, the high-resolution cryo-electron microscopy structures of Schizosaccharomyces pombe Abo1 revealed that it forms a hexameric ring and undergoes a conformational change upon ATP hydrolysis. In addition, single-molecule imaging demonstrated that Abo1 loads H3-H4 histones onto DNA in an ATP hydrolysis-dependent manner. However, the molecular mechanism by which Abo1 loads histones remains unknown. Here, we investigated the details concerning Abo1-mediated histone loading onto DNA and the Abo1-DNA interaction using single-molecule imaging techniques and biochemical assays. We show that Abo1 does not load H2A-H2B histones. Interestingly, Abo1 deposits multiple copies of H3-H4 histones as the DNA length increases and requires at least 80 bp DNA. Unexpectedly, Abo1 weakly binds DNA regardless of ATP, and neither histone nor DNA stimulates the ATP hydrolysis activity of Abo1. Based on our results, we propose an allosteric communication model in which the ATP hydrolysis of Abo1 changes the configuration of histones to facilitate their deposition onto DNA.

• 대한금속재료학회지
• /
• 제47권7호
• /
• pp.406-415
• /
• 2009

A study was conducted on the effects of carbon, tungsten, and vanadium on the wear properties and surface roughness of four High Speed Steel (HSS) rolls manufactured by the centrifugal casting method. Hot-rolling simulation tests were carried out using a high-temperature wear tester capable of controlling speed, load, and temperature. HSS rolls contained a large amount (up to 25 vol.%) of carbides such as MC, $M_{2}C$, $M_{7}C_{3}$, and $M_{6}C$ carbides formed in the tempered martensite matrix. The matrix consisted mainly of lath tempered martensite when the carbon content in the matrix was small, and contained a considerable amount of plate tempered martensite when the carbon content increased. The high-temperature wear test results indicated that the wear properties and surface roughness of the rolls improved when the amount of hard MC carbides formed inside solidification cells increased. The rolls distribution was also homogeneous. The best wear properties and surface roughness were obtained from a roll where a large amount of MC carbides was homogeneously distributed in the lath tempered martensite matrix. The proper contents of carbon equivalent, tungsten equivalent, and vanadium were 2.0~2.3%, 9~10%, and 5~6%, respectively.

• Safety and Health at Work
• /
• 제13권1호
• /
• pp.9-16
• /
• 2022

Background: The global shift toward greener societies demands new technologies and work operations in the waste-management sector. However, progressive industrial methods do not necessarily consider workers' health. This study characterized workers' exposure to bioaerosols and investigated the bioaerosols' potential to engage the immune system in vitro. Methods: Full shift personal aerosol sampling was conducted over three consecutive days. Dust load was analyzed by gravimetry, fungal and actinobacterial spores were analyzed by scanning electron microscopy, and endotoxin by limulus amebocyte lysate (LAL) assay. In vitro exposure of HEK cells to airborne dust samples was used to investigate the potential of inducing an inflammatory reaction. Results: The total dust exposure level exceeded the recommended occupational exposure limit (OEL) of 5.0 mg/m³ in 3 out of 15 samples. The inhalable endotoxin level exceeded the recommended exposure level by a 7-fold, whereas the fungal spore level exceeded the recommended exposure level by an 11-fold. Actinobacterial spores were identified in 8 out of 14 samples. In vitro experiments revealed significant TLR2 activation in 9 out of 14 samples vs. significant TLR4 activation in all samples. Conclusion: The present study showed that the dust samples contained potentially health-impairing endotoxin, fungi, and actinobacterial levels. Furthermore, the sampled dust contained microbial components capable of inducing TLR activation and thus have the potential to evoke an inflammatory response in exposed individuals.

• Computers and Concrete
• /
• 제31권5호
• /
• pp.405-417
• /
• 2023

The submerged floating tunnel (SFT) is tethered by mooring lines anchored to the seabed, therefore, the structural integrity of the anchor should be sensitively managed. Despite their importance, reaction forces cannot be simply measured by attaching sensors or load cells because of the structural and environmental characteristics of the submerged structure. Therefore, we propose an effective method for estimating the reaction forces at the seabed anchor of a submerged floating tunnel using a structural pattern model. First, a structural pattern model is established to use the correlation between tunnel motion and anchor reactions via a deep learning algorithm. Once the pattern model is established, it is directly used to estimate the reaction forces by inputting the tunnel motion data, which can be directly measured inside the tunnel. Because the sequential characteristics of responses in the time domain should be considered, the long short-term memory (LSTM) algorithm is mainly used to recognize structural behavioral patterns. Using hydrodynamics-based simulations, big data on the structural behavior of the SFT under various waves were generated, and the prepared datasets were used to validate the proposed method. The simulation-based validation results clearly show that the proposed method can precisely estimate time-series reactions using only acceleration data. In addition to real-time structural health monitoring, the proposed method can be useful for forensics when an unexpected accident or failure is related to the seabed anchors of the SFT.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2022년도 학술발표회
• /
• pp.334-334
• /
• 2022

Improvement of old-fashioned rain gauge systems for automatic, timely, continuous, and accurate precipitation observation is highly essential for weather/climate prediction and natural hazards early warning, since the occurrence frequency and intensity of heavy and extreme precipitation events (especially floods) are recently getting more increase and severe worldwide due to climate change. Although rain gauge accuracy of 0.1 mm is recommended by the World Meteorological Organization (WMO), the traditional rain gauges in both weighting and tipping bucket types are often unable to meet that demand due to several existing technical limitations together with higher production and maintenance costs. Therefore, we aim to introduce a newly developed and cost-effective hybrid rain gauge system at 0.1 mm accuracy that combines advantages of weighting and tipping bucket types for continuous, automatic, and accurate precipitation observation, where the errors from long-term load cells and external environmental sources (e.g., winds) can be removed via an automatic drainage system and artificial intelligence-based data quality control procedure. Our rain gauge system consists of an instrument unit for measuring precipitation, a communication unit for transmitting and receiving measured precipitation signals, and a database unit for storing, processing, and analyzing precipitation data. This newly developed rain gauge was designed according to the weather instrument criteria, where precipitation amounts filled into the tipping bucket are measured considering the receiver's diameter, the maximum measurement of precipitation, drainage time, and the conductivity marking. Moreover, it is also designed to transmit the measured precipitation data stored in the PCB through RS232, RS485, and TCP/IP, together with connecting to the data logger to enable data collection and analysis based on user needs. Preliminary results from a comparison with an existing 1.0-mm tipping bucket rain gauge indicated that our developed rain gauge has an excellent performance in continuous precipitation observation with higher measurement accuracy, more correct precipitation days observed (120 days), and a lower error of roughly 27 mm occurred during the measurement period.

• 한국산업융합학회 논문집
• /
• 제26권6_3호
• /
• pp.1289-1295
• /
• 2023

Polyurethane foam insulation required for storing and transporting cryogenic liquefied gas is already widely used as a thermal insulation material for commercial LNG carriers and onshore due to its stable price and high insulation performance. These polyurethane foams are reported to have different mechanical performance depending on the density, and the density parameter is determined depending on the amount of the blowing agent. In this study, density-dependent polyurethane foam was fabricated by adjusting the amount of blowing agent. The mechanical properties of polyurethane foam were analyzed in the room temperature and cryogenic temperature range of -163℃ at 1.5 mm/min, which is a quasi-static load range, and the cells were observed through microstructure analysis. The characteristics of linear elasticity, plateau, and densification, which are quasi-static mechanical behaviors of polyurethane foam, were shown, and the correlation between density and mechanical properties in a cryogenic environment was confirmed. The correlation between mechanical behavior and cell size was also analyzed through SEM morphology analysis. Polyurethane foam with a density of 180 kg/m³ had a density about twice as high as that of a polyurethane foam with a density of 96 kg/m³, but yield strength was about 51% higher and cell size was about 9.5% smaller.

• 한국전자통신학회논문지
• /
• 제18권6호
• /
• pp.1239-1244
• /
• 2023

본 연구에서는 캔/PET병 압착파쇄기를 관리하기 위한 IoT 기반의 관리시스템을 개발하였다. 로드셀 2개, 온습도센서 DHT22, 미세먼지 지측정기 등 다양한 센서를 ESP32와 인터페이스하여 IoT 디바이스를 구성하였으며, Node-RED를 활용하여 관리 서버를 구축하였다. 본 시스템은 압착캔과 파쇄된 PET병의 무게를 실시간으로 모니터링하고, 미리 정한 기준치를 초과할 경우 관리자에게 문자 메시지를 전송하여 적시에 수거할 수 있도록 하였다. 운영 시험 결과 본 시스템은 정확한 모니터링과 효율적인 알림 기능을 제공함을 확인하였으며 캔/PET병 과 같은 폐기물 관리의 효율성을 제고하여 환경 문제를 해결할 수 있는 가능성을 제시하였다.

• Steel and Composite Structures
• /
• 제52권3호
• /
• pp.343-356
• /
• 2024

This paper presents an analytical solution for correctly predicting the Lateral-Torsional Buckling critical moment of simply supported castellated beams, the solution covers uniformly distributed loads combined with compressive loads. For this purpose, the castellated beam section with hexagonal-type perforation is treated as an arrangement of double "T" sections, composed of an upper T section and a lower T section. The castellated beam with regular openings is considered as a periodic repeating structure of unit cells. According to the kinematic model, the energy principle is applied in the context of geometric nonlinearity and the linear elastic behavior of materials. The differential equilibrium equations are established using Galerkin's method and the tangential stiffness matrix is calculated to determine the critical lateral torsional buckling loads. A Finite Element simulation using ABAQUS software is performed to verify the accuracy of the suggested analytical solution, each castellated beam is modelled with appropriate sizes meshes by thin shell elements S8R, the chosen element has 8 nodes and six degrees of freedom per node, including five integration points through the thickness, the Lanczos eigen-solver of ABAQUS was used to conduct elastic buckling analysis. It has been demonstrated that the proposed analytical solution results are in good agreement with those of the finite element method. A parametric study involving geometric and mechanical parameters is carried out, the intensity of the compressive load is also included. In comparison with the linear solution, it has been found that the linear stability underestimates the lateral buckling resistance. It has been confirmed that when high axial loads are applied, an impressive reduction in critical loads has been observed. It can be concluded that the obtained analytical solution is efficient and simple, and offers a rapid and direct method for estimating the lateral torsional buckling critical moment of simply supported castellated beams.

• 한국정보전자통신기술학회논문지
• /
• 제11권2호
• /
• pp.144-149
• /
• 2018

인공부화기 내에 종란이 입란하여 18일간 발생기를 거쳐 발육기로 이란을 한다. 발생기 동안 계태아 무게 손실은 곧 기실형성과 상관되며 적당한 기실 형성은 곧 건강한 초생추와 입란 대비 부화율과도 연결된다. 그러나 국내 부화장의 부화기에는 현재 무게를 측정하는 장치 없이 부화실장과 관계자의 경험과 발육기로 이란시 표준 무게 측정으로 결과적 측면을 습득하는 것이 현실이다. 그로 인하여 부화 중 조기 폐사, 약추, 병약한 초생추 발생이 빈번한 실정이다. 종란 중량 감소를 모니터링하는 것은 발육장치기 안에서의 무게 변화에 따른 병아리 품질과 부화율 성과를 얻는 데에 절대적으로 중요하다. 종란의 크기와 난각질, 노계 군에 따라 수분 손실은 각기 다르다. 발육기 안에서 무게 변화를 실시간 측정하고 그에 따른 환기 변화를 최적화하여 부화율의 증가를 기대할 수 있으며 부화 시 전체 무게의 10~13% 감소를 컨트롤할 수 있는 실시간 측정 시스템의 개발 필요성이 대두된다. 본 연구를 통한 시스템은 기존의 입란과 이란시 직접적으로 일회성을 체크하는 방식으로 발육 기간 내에는 계태아 수분 증발 측정 제어가 불가능하여 부화율에 영향을 못 미치는 시스템과 달리 아두이노 스케치 보드에 로드셀 4개를 병렬로 연결하고 실시간으로 휴대폰, 컴퓨터를 연결하기 위해 Hyper-terminal 프로그램을 이용하여 AT-command 명령어를 활용하여 정상적으로 연동하였다. 블루투스의 통신속도는 15200으로 설정하여 아두이노와 Hyper-terminal 프로그램의 통신 속도를 맞춰주었다. 실시간 모니터링을 하여 인공부화기 내의 계태아 무게의 변화를 육안으로 확인할 수 있도록 시스템을 설계하였다. 이와 같은 방법으로 종란의 부화율 상승 및 건강상태의 향상을 목표로 하였으며 실시간 모니터링으로 인하여 사용자의 편의성을 확대하고자 하였다.