• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.19-26
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• 2005

Concentric evacuated tube solar energy collector has been interested recently since government has driven to install alternative energy systems in new large building. In this paper, testing of the evacuated tube collector is conducted in outdoor during daytime by transient method. The collector thermal efficiencies are plotted in term of $(T_{in}-T_a)/Ic$, where $T_{in}$ is inlet working fluid temperature, $T_a$ is atmospheric temperature and $I_c$ is solar irradiation on the collector surface. The evacuated tube collector efficiency is ranged from 50% to 63% in real outdoor condition. In addition, the total overall heat loss coefficient is found to have an inverse variation to $(T_{in}-T_a)/I_c$ so that the coefficient becomes very high when $(T_{in}-T_a)/I_c$ is small.

• KIEAE Journal
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• v.10 no.6
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• pp.105-114
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• 2010

As children are known to touch and chew everything, green cleaning procedures are an important step in preventing children from ingesting harmful toxins. The objectives of this study are to develop a new, self-evaluation checklist and to suggest design recommendations which comply with easy, adaptable, economical ways to improve the eco-friendly indoor environment of Korean childcare facilities. The information compiled during this study was collected through literature review and internet surveys1) from July, 2009 to February, 2010. The results of this study show that the current Korean childcare accreditation system and practices emphasize clean building interiors, policies for sanitation and cleanliness, and control of humidity and lighting. On the other hand, the information provided by green-building rating systems from GBCC, LEED, and GBTool offers additional and comparative details regarding indoor environment quality and standards regarding the IAQ performance and management plan, ventilation and thermal comfort systems, views from windows, acoustics, and lighting. In conclusion, this document provides an appropriate and easy-to-follow, self-evaluation checklist composed of eight criteria and 51 practical items. This study also provides the design recommendations composed of 27 practical ideas focusing on interior elements. Both the checklist and design recommendations I have suggested can be a post-occupancy tool for evaluating eco-healthy facility standards as well as tips for continuing to maintain eco-healthy childcare facilities.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.2
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• pp.105-110
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• 2019

Most titanium alloy waste with cutting oil was discarded without recycling process so that it can be caused by metal and oil fires. However, there is no fire management system and studies on the titanium or titanium alloy waste in spite of high fire risk. The purpose of this experimental study is to identify the fire risk of the titanium alloy waste with cutting oil. We collected the 120g waste which was made in the biomedical titanium alloy cutting process. The waste was burned and conducted thermal image analysis with infrared camera. The experimental results which illustrated the process, characteristics, and trends of fire are presented. Firstly, the cutting oil was burned and partially the titanium alloy waste was burned. The maximum temperature of the fire was more than $650^{\circ}C$ in some specific spots. These results means when a lot of titanium alloy waste with cutting oil was ignited, this fire could connect the titanium fire. In other words, the fire has a flammable liquid fire and combustible metal fire at the same time. The experimental study could be used fire prevention, response, and investigation of the titanium alloy waste.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.413-424
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• 2011

The study was aimed to evaluate the applicability of a three-dimensional (3D) hydrodynamic and water quality model, ELCOM-CAEDYM for Yongdam Reservoir, Korea. The model was applied for the simulations of hydrodynamics, thermal stratification processes, stream density flow propagation, and water quality parameters including dissolved oxygen, nutrients, organic materials, and algal biomass (chl-a) for the period of June to December, 2006. The field data observed at four monitoring stations (ST1~ST4) within the reservoir were used to validate the models performance. The model showed reasonable performance nevertheless low frequency boundary forcing data were provided, and well replicated the physical, chemical, and biological processes of the system. Simulated spatial and temporal variations of water temperature, nutrients, and chl-a concentrations were moderately consistent with the field observations. In particular, the model rationally reproduced the succession of different algal species; i.e., diatom dominant during spring and early summer, after then cyanobacteria dominant under warm and stratified conditions. ELCOM-CAEDYM is recommendable as a suitable coupled 3D hydrodynamic and water quality model that can be effectively used for the advanced water quality management of large stratified reservoirs in Korea.

• Corrosion Science and Technology
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• v.23 no.3
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• pp.203-214
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• 2024

A heat exchanger is a device designed to transfer heat between two or more fluids. In a vehicle's thermal management system, Al heat exchangers play a critical role in controlling and managing heat for efficient and safe operation of the engine and other components. The fluid used to prevent heat exchangers from overheating the engine is mostly tap water. Heat exchange performance can be maintained at sub-zero temperatures using a solution mixed with antifreeze. Although the fluid flowing through the heat exchanger can reduce the temperature inside the engine, it also has various problems such as cavitation corrosion. Cavitation corrosion characteristics in tap water and corrosion characteristics were evaluated in this study when antifreeze was added for test specimens where AA4045 was cladded on the inner surface of AA3003 tubes of a fin-type heat exchanger. The cavitation corrosion resistance of AA3003 was found to be superior to that of AA4045 regardless of the test solution due to higher corrosion resistance and hardness of AA3003 than those of AA4045. The cavitation corrosion rate of Al alloys increased with the addition of antifreeze.

• Journal of Drive and Control
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• v.21 no.2
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• pp.15-22
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• 2024

The objective of this study was to examine whether a gerotor pump used in a transmission could be converted into an electric vehicle thermal management system pump using a virtual design environment. To achieve this objective, we first built an environment that could analyze the performance of a gerotor pump in heat transfer fluid. Flow rate, pressure, and volumetric efficiency were then analyzed when using heat transfer fluid in a gerotor pump. Finally, how large the displacement volume of the pump should be designed when using a heat transfer fluid other than oil was determined. Based on results of this study, it is expected that gerotor pumps will be applied to new business fields such as electric vehicle cooling systems.

• Journal of the Korean Society of Visualization
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• v.22 no.2
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• pp.74-81
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• 2024

Accurate tissue temperature monitoring during clinical procedures, such as laser therapy or surgery, is crucial for ensuring patient safety and treatment efficacy. Noninvasive techniques are essential to prevent tissue disturbance while providing real-time temperature data. However, current methods often struggle to accurately measure temperature at various depths within the skin, which is essential to avoid damage to surrounding healthy tissues due to excessive heat. In response to this challenge, we developed a confocal imaging system that utilizes the laser speckle imaging (LSI) technique for precise depthwise temperature monitoring. LSI uses laser light scattering to capture subtle changes in speckle patterns on the skin's surface due to temperature fluctuations within the tissue. By analyzing these changes, LSI enables accurate depth-resolved temperature measurements. This technique enhances the precision and safety of medical procedures, offering significant potential for broader clinical applications, improved patient outcomes, and better thermal management during interventions.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1863-1872
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• 2006

In FMS (Flexible Manufacturing System) and CIM (Computer Integrated Manufacturing), machine-tools have been the target of integration in the last three decades. The conventional concept of integration is being changed into the autonomous manufacturing device based on the knowledge evolution by applying advanced information technology in which an open architecture controller, high-speed network and internet technology are included. In the advanced environment, the machine-tools is not the target of integration anymore, but has been the key subject of cooperation. In the near future, machine-tools will be more improved in the form of a knowledge-evolutionary intelligent device. The final goal of this study is to develop an intelligent machine having knowledge-evolution capability and a management system based on internet operability. The knowledge-evolutionary intelligent machine-tools is expected to gather knowledge autonomically, by producing knowledge, understanding knowledge, reasoning knowledge, making a new decision, dialoguing with other machines, etc. The concept of the knowledge-evolutionary intelligent machine is originated from the machine control being operated by human experts' sense, dialogue and decision. The structure of knowledge evolution in M2M (Machine to Machine) and the scheme for a dialogue agent among agent-based modules such as a sensory agent, a dialogue agent and an expert system (decision support agent) are presented in this paper, with intent to develop the knowledge-evolutionary machine-tools. The dialogue agent functions as an interface for inter-machine cooperation. To design the dialogue agent module in an M2M environment, FIPA (Foundation of Intelligent Physical Agent) standard platform and the ping agent based on FIPA are analyzed in this study. In addition, the dialogue agent is designed and applied to recommend cutting conditions and thermal error compensation in a tapping machine. The knowledge-evolutionary machine-tools are expected easily implemented on the basis of this study and shows a good assistance to sensory and decision support agents.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.5
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• pp.403-409
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• 2008

Polymer electrolyte membrane fuel cell (PEMFC) is very interesting power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, improvement of performance, effect of temperature and initial start at low temperature. These problems can be approached to be solved by using experiment and mathematical method which are general principles for analysis and optimization of control system for heat and hydrogen detecting management. In this paper, insulation vessel and control system for stable operation of fuel cell at low temperature were developed for experiment. The constant temperature capability and the heating time at sub-zero temperatures with insulation control system were studied by using a heating bar of 60W class. PEMFC stack which was made by 4 cells with $50\;mc^2$ active area in each cell is a thermal source. Times which take to reach constant temperature by the state of insulation vacuum were measured at variable environment temperatures. The test was performed at two conditions: heating mode and cooling mode. Constant temperature capability was better at lower environment temperature and vacuum pressure. The results of this experiment could be used as basis data about stable operation of fuel cell stack in low temperature zone.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1935-1941
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• 2021

In order to develop an algorithm using deep learning, which has been recently applied to various fields, it is necessary to have rich, high-quality learning data. In this paper, we propose an acquisition system for biological signals that simultaneously collects bio-signal data such as optical videos, thermal videos, and voices, which are mainly used in developing deep learning algorithms and useful in derivation of information, and transmit them to the server. To increase the portability of the collector, it was made based on Raspberry Pi, and the collected data is transmitted to the server through the wireless Internet. To enable simultaneous data collection from multiple collectors, an ID for login was assigned to each subject, and this was reflected in the database to facilitate data management. By presenting an example of biological data collection for fatigue measurement, we prove the application of the proposed acquisition system.