PURPOSES : This study aimed to compare the object detection performance based on various analysis methods using point-cloud data collected from LiDAR sensors with the goal of contributing to safer road environments. The findings of this study provide essential information that enables automated vehicles to accurately perceive their surroundings and effectively avoid potential hazards. Furthermore, they serve as a foundation for LiDAR sensor application to traffic monitoring, thereby enabling the collection and analysis of real-time traffic data in road environments. METHODS : Object detection was performed using models based on different point-cloud processing methods using the KITTI dataset, which consists of real-world driving environment data. The models included PointPillars for the voxel-based approach, PartA2-Net for the point-based approach, and PV-RCNN for the point+voxel-based approach. The performance of each model was compared using the mean average precision (mAP) metric. RESULTS : While all models exhibited a strong performance, PV-RCNN achieved the highest performance across easy, moderate, and hard difficulty levels. PV-RCNN outperformed the other models in bounding box (Bbox), bird’s eye view (BEV), and 3D object detection tasks. These results highlight PV-RCNN's ability to maintain a high performance across diverse driving environments by combining the efficiency of the voxel-based method with the precision of the point-based method. These findings provide foundational insights not only for automated vehicles but also for traffic detection, enabling the accurate detection of various objects in complex road environments. In urban settings, models such as PV-RCNN may be more suitable, whereas in situations requiring real-time processing efficiency, the voxelbased PointPillars model could be advantageous. These findings offer important insights into the model that is best suited for specific scenarios. CONCLUSIONS : The findings of this study aid enhance the safety and reliability of automated driving systems by enabling vehicles to perceive their surroundings accurately and avoid potential hazards at an early stage. Furthermore, the use of LiDAR sensors for traffic monitoring is expected to optimize traffic flow by collecting and analyzing real-time traffic data from road environments.

With the growth of silicon-based semiconductor sensors in the global sensor market, advancements in body motion detection for wearable devices and sustainable health monitoring have accelerated. This has led to a significant attention on various sensors with excellent flexibility and stretchability, such as PDMS, in numerous applications. In this study to adjust the sensitivity of conventional conductive pressure sensors, a porous sponge structure was initially created using a sugar template method. The polymer was prepared with four different ratios (5:1, 10:1, 20:1, 30:1) to achieve varying flexibilities. To ensure conductivity, the sponge was coated using a dip-coating method with a 3wt% CNT solution. The conductive sponges with various ratios were tested for sensitivity, demonstrating characteristics suitable for a wide range of pressure sensing applications.

본 연구에서는 탄소나노튜브(CNT) 패치 센서를 기반으로 하여 구조물의 이상 거동을 감지하고 대 응할 수 있도록 하는 첨단 스마트 모니터링 시스템을 제안한다. 복합소재로 제작되는 CNT 센서는 유 연한 특성을 갖게 되어 다양한 형태의 구조물 표면에 적용할 수 있으며, 이를 통해 충격이나 피로 등 에 의해 발생되는 균열과 같은 비정상적인 거동을 감지할 수 있다. CNT 센서를 통해 수집한 데이터 는 IoT 시스템을 통해 실시간으로 분석되어 구조물의 거동 상태를 확인하고 건전성을 모니터링 할 수 있게 한다. 이 시스템의 성능 검증 및 사용성 검토를 위해 미국 소재 교량에서 실증 테스트를 하였으 며, 테스트 결과 CNT 센서를 이용한 구조물 거동 감지 시스템을 통해 구조물의 이상 거동을 효과적 으로 감지하고 모니터링하여 구조물에서 발생 될 수 있는 잠재적 문제를 사전에 예방할 수 있음을 확 인하였다. 이와 같은 기술은 추후 다양한 분야에서 적극적으로 활용될 수 있을 것으로 기대된다.

항만 내 선박과 부두의 사고를 예방하기 위하여 통항 및 접안 안전성 평가를 통하여 안전한 부두가 건설되어 관리하고 있으나, 선 박의 접안 및 계류 과정에서 선박이 부두에 충돌하거나 로프로 인한 인명사고의 발생 등 예측할 수 없는 사고들이 종종 발생한다. 자동계류장 치는 선박의 신속하고 안전한 계류를 위한 자동화된 시스템으로 로봇 매니퓰레이터와 흡착 패드로 구성된 탈/부착 메커니즘을 가지고 있다. 본 논문은 자동계류장치의 흡착 패드의 위치 및 속도제어에 필요한 선체와의 변위 및 속도 측정 시스템을 다룬다. 자동계류장치에 적합한 측 정 시스템을 설계하기 위하여, 본 논문은 우선 센서의 성능 및 실외 환경적 특성 분석을 수행한다. 다음으로 이러한 분석 결과를 토대로 실외 부두환경에서 설치되는 자동계류장치에 적합한 변위 및 속도 측정시스템의 구성 및 설계 방법에 대해 기술한다. 또한 센서의 측정상태 감지 및 속도 추정을 위한 알고리즘을 제시한다. 제안된 방법은 다양한 속도 구간에서의 변위 및 속도 측정 실험을 통해 그 유용성을 검증한다.

In this study, the performances of H2S, NH3, and HCl sensors for real-time monitoring in small emission facilities (4, 5 grades in Korea) were evaluated at high concentration conditions of those gases. And the proper approach for the collection of reliable measurement data by sensors was suggested through finding out the effect on sensor performances according to changes in temperature and humidity (relative humidity, RH) settings. In addition, an assessment on sensor data correction considering the effects produced by environmental settings was conducted. The effects were tested in four different conditions of temperature and humidity. The sensor performances (reproducibility, precision, lower detection limit (LDL), and linearity) were good for all three sensors. The intercept (ADC0) values for all three sensors were good for the changes of temperature and humidity conditions. The variation in the slope value of the NH3 sensor showed the highest value, and this was followed by the HCl, H2S sensors. The results of this study can be helpful for data collection by enabling the more reliable and precise measurements of concentrations measured by sensors.

The high-level nuclear waste (HLW) repository disposes of high-level nuclear waste at a depth of 500 m to 1,000 m underground. Structural health monitoring must be accompanied by the complex environmental conditions of high temperature, high humidity, radiation, and mechanical stress. A thermocouple for measuring temperature, total stress meter and pore pressure meter for measuring stress and water pressure, relative hygrometer and electrical resistivity sensor (TDR or SUS) for measuring humidity, accelerometer for measuring crack signals, and strain gauge for measuring displacement are used. For safety, after disposing of HLW in the HLW repository, access to the disposal tunnel gets blocked, making it impossible to replace or remove the monitoring sensors. So, it is necessary to evaluate the effect of the HLW repository’s environmental conditions on the monitoring sensors and enhance their durability through quantitative life evaluation and shielding. Before evaluating the life of accelerometers and strain gauges used in the HLW repository, an experimental study is conducted to determine failure modes and failure mechanisms under radiation conditions, which are unique environmental conditions of the HLW repository.

In the nuclear environment, sensors ensure safety, monitoring, and operational efficiency under various operating conditions. These sensors come in various forms, each tailored to specific purposes, including nuclear safety and security, waste treatment and storage, gas leak detection, temperature and humidity monitoring, and corrosion detection. Ensuring the longevity of sensors without the need for frequent replacements is a vital goal for researchers in this field. This paper explores materials that can act as shields to protect sensors from harsh environmental conditions (high radiation and temperatures) to enhance their lifetime. The types of material that had been explored were divided into categories: metal and non-metal. Fourteen types of metal and seven different plastic materials were studied and focused on their characteristics and current applications. Considering properties like melting point, intensity, and conductivity, plastic materials are chosen to be examined as sensor shielding material. A preliminary experiment was conducted to verify signal characteristics changes by shielding material. Metal material and plastic material each were placed in the middle of the granite and the target sensor. The result showed that when metal is between the granite and the sensor, the density and impedance are higher in granite than in the metal. This leads to signal attenuation and a shift in resonance frequency, while plastic does not. Therefore, PPS (Polyphenylene sulfide) and PAI (Polyamide-imide) have lower density and impedance than granite while also possessing heat, moisture, and radiation resistance for effective shielding.

Owing to the great demand for portable and wearable chemical sensors, the development of all-solid-state potentiometric ion sensors is highly desirable considering their simplicity and stability. However, most ion sensors are challenged by the penetration of water and gas molecules into ion-selective membranes, causing unstable and undesirable sensing performances. In this study, a hydrophobic ionic liquid-modified graphene (Gr) sheet was prepared using a fluid dynamics-induced exfoliation and functionalization process. The high hydrophobicity and electrical double-layer capacitance of Gr make it a potential solid-state ion-to-electron transducer for the development of potentiometric sodium-ion ( Na+) sensors. The as-prepared Na+ sensors effectively prevented the formation of the water layer and penetration of gas species, resulting in stable and high sensing performances. The Na+ sensors showed a Nernstian sensitivity of 58.11 mV/[Na+] with a low relative standard deviation (0.46), fast response time (5.1 s), good selectivity (K < 10− 4), and good durability. Furthermore, the Na+ sensor demonstrated its feasibility in practical applications by measuring accurate and reliable ion concentrations of artificial human sweat and tear samples, comparable to a commercial ion meter.

This study monitored temperature using electronic sensors and developed a prediction model for compost maturity. The experiment used swine manure in a mechanical composting facility equipped with a screw-type agitator, and the composting process was conducted for 60 d during the summer season in South Korea. Four electronic temperature sensors were installed on the inner wall between the compost piles on Days 7, 14, 21, and 28 for daily temperature monitoring. Compost samples were collected daily for 60 d, and compost maturity was analyzed using the Solvita method. Multiple comparisons, correlations, and modeling were performed using the stat package in R software. The average compost pile temperatures was 39.1±3.9, 36.4±4.3, 31.3±4.5, and 35.4±8.1 on days 7, 14, 21, and 28, respectively, after composting. The average compost maturity according to the composting date was 3.61±0.60, 4.13±0.59, 4.26±0.47, and 4.32 ±0.56 on days 7, 14, 21, and 28, respectively. A significant negative correlation was observed between the compost composting periods (seven, 14, 21, and 28 d) and the temperature of all compost piles (p<0.05), where the correlation coefficients were -0.329, -0.382, -0.507, and -0.634, respectively. A significant positive correlation was observed between the compost composting periods (seven, 14, 21, and 28 d) and the maturity of the compost (p<0.05), where the correlation coefficients were 0.410, 0.550, 0.727, and 0.840, respectively. The model for predicting the maturation of the 14 d average compost pile according to the compost composting period and the average temperature for 14 d was y=0.026 x d – 0.021 x mt.x_14 d (mean temperature for 14 d) + 4.336 (R2=0.7612, p<0.001). This study can be considered a basic reference for predicting compost maturity by the proposed model using electronic temperature sensors.

In this paper, we proposed and tested an indoor obstacle recognition and avoidance algorithm using vision and ultrasonic sensors for effective operation of drone with low-power. In this paper, the indoor flight of a drone is mainly composed of two algorithms. First, for the indoor flight of the drone, the vanishing point and the center point of the image were extracted through Hough transform of the input image of the vision sensor. The drone moves along the extracted vanishing point. Second, we set an area of interest so that the drone can avoid obstacles. The area of interest is a space where the drone can fly after recognizing an obstacle at a distance from the ultrasonic sensor. When an obstacle is recognized in the drone's area of ​​interest, the drone performs an obstacle avoidance action. To verify the algorithm proposed in this paper, a simple obstacle was installed in an indoor environment and the drone was flown. From the experimental results, the proposed algorithm confirmed the indoor flight and obstacle avoidance behavior of the drone according to the vanishing point.

수처리 후 직접 해양으로 배출하는 산업시설 등에서 Hazardous and Noxious Substance (HNS) 농도 변화를 연속 자동 측정하기 위 한 센서의 기본적 성능으로 상온에서도 ppb 수준의 검출이 가능한 센서가 필요하다고 판단하여 기존의 센서의 감도를 높이기 위한 방법 을 제안하였다. 우선 나노입자 박막에 전도성 탄소계 첨가물을 이용하여 필름의 전도도를 높이는 방법과 촉매 금속을 이용하여 표면에서 의 이온 흡착도를 높이는 방법에 대해서 각각 연구하였다. 전도성 개선을 위해서 ITO 나노입자를 활용한 필름에 carbon black을 첨가물로 선택하여, 첨가물 함유량에 따른 센서의 성능변화를 관찰하였다. 그 결과 CB 함량 5 wt% 정도에서 전도성 증가에 의한 저항과 응답시간 의 변화를 관찰할 수 있었고, 유기용제를 대상으로 한 실험에서 검출하한은 250 ppb 정도까지 낮아지는 것을 확인하였다. 또한 액체 중 이 온 흡착도를 높이기 위하여 센서 표면에 촉매로 Au를 스퍼터로 제작한 표면 촉매층을 형성한 시료를 이용한 실험에서 센서의 응답은 20% 이상 증가하고 평균 검출하한은 61 ppm까지 낮아지는 것을 확인하였다. 이 결과로부터 금속산화물 나노입자를 활용한 화학저항형 센서가 상온에서도 수십 ppb 정도의 HNS를 검출할 수 있다는 것을 확인하였다.

PURPOSES : The purpose of this study was to quantitatively evaluate the variability of LiDAR performance indicators, such as intensity and Number of Point Cloud(NPC), according to various environmental factors and material characteristics. METHODS : To consider the material characteristics of road safety facilities, various materials (Reference Material(RM), reflective sheet, matte sheet, granite, plastic, and rubber) were used in a darkroom, and the performance indicators of LiDAR were repeatedly measured in terms of changes in the measurement distance, rainfall, and angle of observation. RESULTS : In the case of standard reflective materials, the intensity measurement value decreased as the measurement distance and rainfall increased. The NPC showed a tendency to decrease as the measurement distance increased, regardless of rainfall intensity. For materials with high-intensity values, it was found that rainfall intensity and color had negligible effect on the change in intensity compared with the measurement distance. However, for materials with low-intensity values, it was found that the measurement distance, rainfall intensity, and color all had a significant effect on the change in intensity. CONCLUSIONS : For materials with high-intensity values, it was found that rainfall and color had negligible effect on change in intensity compared with the measurement distance. However, for materials with low-intensity values, the measurement distance, rainfall, and color all had a significant effect on the change in intensity value.

본 연구의 목적은 루어낚시 참여자의 손목 움직임 측정을 위한 스트레치 센서를 개발하는 것이다. 손목움직임 측 정을 위해 스트레치 센서를 손목에 부착하여 배굴, 저굴 그리고 랜딩동작을 게이지율, 인장강도 그리고 신장회복률 을 척도로 실험을 진행하였다. CNT 분산액을 이용한 전도성 센서를 개발하고 E-band에 동일한 조건으로 적용하였 다. 함침을 각각 한 번, 두 번, 그리고 세 번한 같은 크기의 5종, 15가지 센서를 만능재료시험기(Dacell dn-fga Universal testing machine, UTM)를 활용해 게이지율(Gauge Factor)을 측정하였다. 두 번 함침한 센서가 게이지율이 가장 우수했으며, 게이지율과 인장강도가 높은 세 가지 센서로 프로토 타입을 제작하였다. 아두이노에 연결하여 동작테스트를 한 결과, 인장강도와 게이지율이 가장 높은 시료 1이 세 가지 동작에서 일정한 파장이 유지되었다. 시료 2,3은 배굴과 저굴에서는 일정한 파장을 나타내었지만, 랜딩동작에서는 신호 노이즈가 나타났다. 이는, 랜딩동작에서 는 인장강도와, 게이지율에 따라 파장의 패턴이 다르게 나타나는 것을 알 수 있었다. 이와 같은 결과로 손목의 움직 임 측정을 위한 스트레치 센서 제작시에 필요한 조건들을 유추할 수 있었다. 본 연구의 결과를 활용하여 루어낚시용 스마트 웨어러블 제품 개발에 응용이 가능할 것으로 사료된다.

Food toxins are regarded as a major source of health risks, serious illnesses susceptible to even death. These dangerous pathogens may lead to significant economic impact worldwide. The food production chain undergoes different stages like harvesting, processing, storage, packaging, distribution, and lastly preparation, and consumption. Therefore, each step is susceptible to risks of environmental contamination. Nowadays, the carbon quantum dots (CDs) are regarded as one of the most widely used hybrid carbon nanomaterials due to their different magical physical and chemical properties. The CDs have a size below 10 nm and show the fluorescent property. The CDs find vast applications in different fields like sensing, food safety, drug delivery, bioimaging, catalyst, energy conversion, etc. Compared to other available methods, the fluorescence detection techniques have low cost, easy handling, and safe operating system. There is a need for a review to compile the fluorescence properties of carbon nanodots used to detect food pathogens. This brief review is addressed in that direction and mostly focused on the synthesis of carbon dots-based fluorescence sensors for detecting pathogens and toxins in foods and beverages. The detailed mechanisms and origin of fluorescence properties of carbon quantum dots are also highlighted herewith.

High level nuclear waste (HLW) is surely disposed in repository in safe by being separated from human life zone. Deep geological disposal method is one of the most potent disposal method. Deep geological repository is exposed to high pressure and groundwater saturation due to its depth over 500 m. And it is also exposed to high temperature and radiation by spent fuels. Thus, HLW repository suffers extremely complex thermo-hydro-mechanical-radioactive condition. Long-term integrity of repository should be verified because the expected lifetime of the repository is over 10,000 years. However, the integrity of monitoring sensors are not reach the endurance lifetime of the repository with present technology. And the disposal condition, thermo-hydro-mechanical-radioactive, should shorten the estimated lifetime of the monitoring sensors. Therefore, it is necessary to improve the long-term integrity of the monitoring sensors. Although long-term tests are required to identify the prolonged durability of monitoring sensors, accelerated tests can help curtail test period. Accelerated tests is classified into accelerated stress test and accelerated degradation test and their methodology and theories are investigated. Their tests are design and proceed by following process: 1) identify failure modes, 2) select accelerated stress parameter, 3) Determine stress level, 4) Determine testing time and number of specimens, 5) Define measurement paremeter and failure criteria, 6) Suggest measurement method and measurement duration. Literature reviews were conducted to identify the influence of the disposal conditions such as thermo-hydro-mechnical-radioactive on integrity of material and monitoring sensors. The investigated data reported in this paper will be utilized to verify the improvement of integrity of monitoring sensors.