• Journal of Wind Energy
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• v.9 no.4
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• pp.9-15
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• 2018

In a previous study, a technique for measuring wind speed and direction by using a roll-rotating three-axis ultrasonic anemometer was proposed and verified by wind tunnel tests. In the tests, instead of a roll sensor, roll angle was trimmed to make no up flow in the transformed wind speeds. Verification was done in point of the residual error of the rotation effect treatment. In this study, roll angle was measured from the roll motor encoder and the transformed wind speed and direction on the test section axis were compared with the ones provided to the test section. As a result, up to yaw $20^{\circ}$ at a wind speed of 12 m/sec or over, the RMS error of wind speed was within the double of the ultrasonic anemometer error. But at yaw $30^{\circ}$, it was over the double of the ultrasonic anemometer error. Regardless of wind speed, at yaw $20^{\circ}$ and $30^{\circ}$, the direction error was within the double of the ultrasonic anemometer error. But at yaw $10^{\circ}$ or less, it was within the error of the ultrasonic anemometer itself. This is a very favorable characteristic to be used for wind turbine yaw control.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.691-698
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• 2020

In this study, the effects of hydrodynamic interceptors on a high-speed vessel were investigated to identify the operating principle based on experiments. Model tests were performed using a high-speed towing carriage. The resistance, trim and rise of Center of Gravity (CG) of the high-speed vessel were measured for various ship speeds and interceptor heights. As the interceptor height increased, the trim and rise of CG were reduced. In order to quantitatively analyze these phenomena, the pressure at the stern bottom was measured using tactile sensors. The reliability of the measured results from the tactile sensors was verified through repeat tests. The pressure on the stern bottom increased in proportion to the interceptor height, as the interceptor partially blocked the flow there. Then, the trim was reduced. However, as the ship speed increases, the pressure at the location close to the interceptor decreases when the interceptor height is small, leading to increased trim. Therefore, the interceptor height for running attitude control should be carefully determined considering multiple factors in the operating condition of the high-speed planing hull.

• Journal of Information Processing Systems
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• v.16 no.6
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• pp.1459-1478
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• 2020

In the last few years, quantum communication technology and services have been developing in various advanced applications to secure the sharing of information from one device to another. It is a classical commercial medium, where several Internet of Things (IoT) devices are connected to information communication technology (ICT) and can communicate the information through quantum systems. Digital communications for future networks face various challenges, including data traffic, low latency, deployment of high-broadband, security, and privacy. Quantum communication, quantum sensors, quantum computing are the solutions to address these issues, as mentioned above. The secure transaction of data is the foremost essential needs for smart advanced applications in the future. In this paper, we proposed a quantum communication model system for future ICT and methodological flow. We show how to use blockchain in quantum computing and quantum cryptography to provide security and privacy in recent information sharing. We also discuss the latest global research trends for quantum communication technology in several countries, including the United States, Canada, the United Kingdom, Korea, and others. Finally, we discuss some open research challenges for quantum communication technology in various areas, including quantum internet and quantum computing.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.64-68
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• 2022

Herein, we propose a LoRaWAN-based small draft system that can measure the ocean current flow (speed, direction, and distance) in real time at the request of the Coast Guard to develop a device that can promptly find survivors at sea. This system has been implemented and verified in the early stages of rescue after maritime vessel accidents, which are frequent. GPS signals often transmit considerable errors, so correction algorithms using the improved triangulation method algorithm are required to accurately indicate the direction of currents in real time. This paper is structured in the following manner. The introduction section elucidates rescue activities in the case of a maritime accident. Chapter 2 explains the characteristics and main parameters of the GPS surveying technique and LoRaWAN communication, which are related studies. It explains and expands on the critical distance error correction algorithm for GPS signals and its improvement. Chapter 3 discusses the design and analysis of small draft buoys. Chapter 4 presents the testing and validation of the implemented system in both onshore and offshore environments. Finally, Section 5 concludes the study with the expected impact and effects in the future.

• Particle and aerosol research
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• v.18 no.3
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• pp.61-68
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• 2022

In this study, a fluidized bed particle generator was developed to generate an aerosol without supply of compressed air and to increase portability. It was assumed that the mixing ratio of the test particles and beads, the input amount, and the air flow rate supplied to the generator would have effect on the aerosol generation characteristics. The product of these three parameters was set as a characteristic parameter and particle generation characteristics according to the change of the characteristic parameter were observed. As a result, it was confirmed that the input amount of test particles and beads was not suitable as a characteristic parameter and a characteristic parameter expressed as a product of the mass mixing ratio and the air flowrate was newly defined. When the new characteristic parameter is applied, it can be confirmed that the total amount of particles generated from the particle generator is a function of the characteristic parameter. As a result of measuring the amount of particle generation by adjusting the characteristic parameter, it was confirmed that the performance required for the test particle generator for the field inspection equipment of PM-2.5 sensors could be satisfied.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.559-573
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• 2023

Shiga toxin (Stxs)-producing enterohaemorrhagic Escherichia coli (EHEC) and Shigella dysenteriae serotype 1 are major causative agents of severe bloody diarrhea (known as hemorrhagic colitis) and hemolytic uremic syndrome (HUS) associated with extraintestinal complications such as acute renal failure and neurologic impairment in infected patients under 9 years of age. Extreme nephrotoxicity of Stxs in HUS patients is associated with severe outcomes, highlighting the need to develop technologies to detect low levels of the toxin in environmental or food samples. Currently, the conventional polymerase chain reaction (PCR) or immunoassay is the most broadly used assay to detect the toxin. However, these assays are laborious, time-consuming, and costly. More recently, numerous studies have described novel, highly sensitive, and portable methods for detecting Stxs from EHEC. To contextualize newly emerging Stxs detection methods, we briefly explain the basic principles of these methods, including lateral flow assays, optical detection, and electrical detection. We subsequently describe existing and newly emerging rapid detection technologies to identify and measure Stxs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.569-570
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• 2021

Hydroponic cultivation is of considerable interest to the production of high-quality green plants. However, establishing the planting operating systems in hydroponic cultivation may result in chronic problems, such as the reproduction of harmful bacteria throughout the circulating culture fluid. Extensive research has been conducted on using an ultraviolet sterilization system to prevent culture fluid contamination. In this study, the proposed module, using UV-C LEDs that emit wavelengths between 270 and 285 nm, was designed along with a sensor and controller. The module was set to emit 300, 500, and 700 mW, for different culture fluid flow rates, to investigate its capacity to eliminate Escherichia coli, Clavibacter michiganensis, Pseudomonas cichorii, and Fusarium oxysporum.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.391-393
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• 2021

In this paper, we introduce a long short-term memory (LSTM)-based fall detection system using TensorFlow that can detect falls occurring in the elderly in daily living. 3-axis accelerometer data are aggregated for fall detection, and then three types of parameter are calculated. 4 types of activity of daily living (ADL) and 3 types of fall situation patterns are classified. The parameterized data applied to LSTM. Learning proceeds until the Loss value becomes 0.5 or less. The results are calculated for each parameter θ, SVM, and GSVM. The best result was GSVM, which showed Sensitivity 98.75%, Specificity 99.68%, and Accuracy 99.28%.

• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.418-424
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• 2023

Natural killer (NK) cells play a crucial role in combating infections and tumors. However, their therapeutic application in solid tumors is hindered by challenges, such as limited lifespan, tumor penetration, and delivery precision. Our research introduces a novel ultrasonic actuation technique to navigate NK cells more effectively in the vascular system, particularly at vessel bifurcations where targeted delivery is most problematic. We use a hemispherical ultrasonic transducer array that generates phase-modulated traveling waves, focusing on an ultrasound beam to steer NK cells using blood-flow dynamics and a focused acoustic field. This method enables the precise obstruction of non-target vessels and efficiently directs NK cells toward the tumor site. The simulation results offer insights into the behavior of NK cells under various conditions of cell size, radiation pressure, and fluid velocity, which inform the optimization of their trajectories and increase targeting efficiency. The experimental results demonstrate the feasibility of this ultrasonic approach for enhancing NK cell targeting, suggesting a potential leap forward in solid tumor immunotherapy. This study represents a significant step in NK cell therapeutic strategies, offering a viable solution to the existing limitations and promising enhancement of the efficacy of cancer treatments.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.131-134
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• 2024

본 논문에서는 기존 철도 운영 및 관리시에 철도 주변환경으로 부터 발생하는 소음, 진동, 미세먼지 센서에서 다양한 실시간 스트림 데이터를 감지하고 정형화된된 데이터 패턴을 인식하고 분석할 수 있도록 데이터를 구성 및 저장하고 분석된 데이터를 표현할 수 있도록 시각화 지원을 위한 모니터링 시스템 플랫폼을 구현하였다. 데이터 전송을 위해 시리얼 통신 기법을 주로 적용하였으나, 센서와 디바이스의 증가로 인해 시리얼 통신의 한계가 나타났다. 따라서, 본 연구에서는 기존의 아두이노와 서버 간의 직접 통신 방식 대신 라즈베리파이를 도입하여 MQTT Broker(브로커)를 설치하고 통신을 진행하였다. 철도 데이터 모니터링 시스템 플랫폼은 NoSQL 데이터베이스인 MonGoDB와 데이터 시각화할 수 있는 Grafana를 이용하여 구축하였다.