• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.584-589
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• 2006

In this paper, a test apparatus for reliability evaluation of a rotary compressor has been suggested with a short-cycle concept. $CO_2$ refrigerant is adopted for this cycle to avoid phase change during cycle operation. Evaporator is not necessary in short-cycle. Utilizing a short-cycle, the test apparatus was built on the purpose of evaluating the reliability of each rotary compressor on the conveyer belt of the factory. The primary validation of the test apparatus is discussed by analyzing the experimental heat balance data. Additional validation was performed through the overload continuous operation test where the wear rate of the $CO_2$ short-cycle was found to similar to that of the R22 normal-cycle. The reliability evaluation test apparatus with a short-cycle in present investigation was found simple and efficient in the view of reducing sample numbers, costs, and test time in analyzing the reliability of rotary compressors.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.767-772
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• 2006

The SWTR(Surface Water Treatment Rule) requires achieving removal 99.9% Giardia and 99.99% Virus. To remove Giardia and Virus, disinfection process is essential process. CT is important index for Disinfection performance. CT value is expressed by CXT. C is represented by disinfection concentration and T is represented by $T_{10}$ which means 90% contact time in clearwell. To improve Disinfection performance, it is desirable to increase $T_{10}$. Primary factor affected $T_{10}$ is flow Pattern. Because guide wall change that flow pattern is uniform, we have installed guide wall to increase $T_{10}$. In this paper, we have performed numerical analysis for clearwell installed symmetric guide wall and center divided guide wall using CFD. We have analyzed flow pattern and $T_{10}$ in each clearwell. And. we compare symmetric guide wall with center divided guide wall in flow pattern and $T_{10}$.

• Korean Journal of Veterinary Research
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• v.61 no.3
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• pp.25.1-25.7
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• 2021

The axolotl has extraordinary regeneration capacity compared to other vertebrates. This remarkable potential has been attributed to its life-long neoteny, characterized by the exhibition of embryonic characteristics at the adult stage. A recent study provided a detailed morphological analysis of the sperm morphology of the Ambystoma mexicanum using routine and detailed histological techniques. The primary purpose of the present study is to describe a simple and inexpensive method for evaluating the morphology of axolotl sperm. In this study, spermatophore structures were collected and spread on slides and air-dried. The slides were stained with periodic acid Schiff, toluidine blue, Masson's trichrome, Giemsa, Spermac, and Diff-Quik dye for a morphological examination. The slides were coated with gold/palladium for a scanning electron microscopy examination. The sperm of the axolotl consisted of an elongated head, a neck, and a flagellum covered with an undulating membrane. The lengths of the midpiece, tail, and head were 8.575 ㎛, 356.544 ㎛, and 103.661 ㎛, respectively. In the flagellum part, the wavy membrane structure, whose function has not been explained, surrounds the tail. The data obtained from this study will constitute an important step in designing future research on the reproductive and regeneration capacity of the axolotl.

• Journal of the Korean Institute of Educational Facilities
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• v.26 no.3
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• pp.3-13
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• 2019

Purpose: The human body is a chemical laboratory. Artists are exposed to a variety of chemicals in art studio space and the art materials used in the creation contain toxic ingredients, exposing them to a variety of incurable diseases, including cancer. It aims to analyze the problems of the studio space environment and the risks of art materials, which are fundamental causes of the outbreak of incurable diseases, and to derive the direction of specific practices that can reduce the occurrence of incurable diseases by artists. Method: The harmfulness of an artist's creative space is the cause of a disease outbreak, and two primary factors cause it. One is the environmental hazards caused by the use of tools, air pollution, and chemical hazards caused by art materials in the architectural space environment of the studio. Necessary measures are put forward to control disease outbreaks by identifying the status and cause of intractable diseases caused by studies. Result: The plan is urgent for the establishment of safety rules and regular pre-trainthese two factors and analyzing the results of prior research and implementation investigationing, the legal provisions of studio architecture design and the introduction of labelling rules to control the distribution of harmful art materials.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.27 no.2
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• pp.54-69
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• 2019

The primary objective of this paper is to introduce the application of Human-Machine Interface (HMI) and Augmented Reality (AR) technologies in flight operations. These include: self-check-in, baggage handling, airport security and surveillance, airport operations monitoring, In-Flight Entertainment and Connectivity (IFEC), cockpit design, and cabin crew support. This paper investigates the application status and development trends of HMI and AR technologies for airports and aircraft. These technologies can provide more efficient in-flight passenger service and experience by using AR devices. This paper also discusses the developments such as; the Integrated Control Application (ICA) for the IFEC interface, AR flight simulation training program using the fixed-based simulator, and the AR aircraft cabin interior concept test program. These applications present how HMI and AR techniques can be utilized in actual flight operations. The developed programs in this paper can be applied to their purpose within aircraft interiors and services to enhance efficiency, comfort, and experience.

• Transactions of Materials Processing
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• v.28 no.5
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• pp.266-274
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• 2019

Metal sealing is used to connecting the parts between valves and fuel pipes for a FCEV which utilizes hydrogen gas of 700 bar. Instead of general carbon steel, stainless steel is the primary material used to manufacture fuel pipes due to hydrogen embrittlement. The shape of deformation between metals is an important factor on the air-tightness of the metal to metal contact. Since the stainless steel pipe is hardened using the plastic forming during the tip shaping stage, this work hardening could have an effect on the deformed shape and characteristics of contact surfaces in fastening of pipes. In this paper, the deformation history of the pipe model was considered in order to analyze the hydrogen-tightness on the metal sealing part. The contact distance and the forward displacement for fastening were compared using experimental results and the simulation results. The simulation of the effect of material change on the fitting body demonstrated that the hardness or the strength of the formed tip of the pipe was designed to a proper valued level since the characteristics of the contact surface was exhibited better when the strength of the pipe was lower than that of the fitting body.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.5
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• pp.436-447
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• 2019

The circulating fluidized bed boiler has an advantage that can burn a variety of fuels from low-grade fuel to coal. In this study, for the design of a circulating fluidized bed boiler using wood pellets, a circulating fluidized bed combustion test device using no external heater was manufactured and used. According to the increase of co-combustion rate with wood pellet, combustion fraction and heat flux by combustor height were measured and pollutant emission characteristics were analyzed. In terms of combustibility, the effect on primary and secondary air ratio were also studied. In addition, as a result of analysis of the effect of corrosive nanoparticles on the combustion of coal with wood pellets, it was confirmed that coal is mostly composed of Ca and S, whereas wood pellets are mostly composed of K, Cl, and Na.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.3
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• pp.525-545
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• 2021

The purpose of this study was to assess the sustainability of laundry practices among Korean households in comparison with European households. A total of 329 responses were collected through an online survey and analyzed using SPSS. Detergent dosing, use of fabric softener, prewashing, rinsing, washing programs, and washing temperatures of Korean households were not optimal for sustainability. Only 11.2% of respondents followed dosage instructions while the majority based on load size. Use of fabric enhancer, prewashing, and rinsing were frequent. Cotton 40℃ was the most frequently used program (81.5%) while eco and cold wash programs were among the least (1.5%). In terms of laundry sorting, load size, drying, and ironing, more sustainable actions were reported. Laundry was often sorted by color, machines were commonly filled, and clothes tended to be air-dried and not excessively ironed. Gender was the primary socio-demographic factor denoting sustainable habits, with males being more attentive to instructions and care labels than females. European households, however, were more sustainable in all areas except for frequent ironing, and education level and employment status were significant factors affecting sustainable practices.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.95-100
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• 2022

In this paper, a power loss analysis technique of a high-frequency transformer of a bidirectional DAB (Dual Active Bridge) converter is reported. To miniaturize the transformer of the dual active bridge converter, a resonant inductor was designed with an air gap included low-coupled rate state core to combine leakage inductor with the resonant inductor which is required for soft-switching. In this paper, leakage inductance and magnetizing inductance, core material, type of winding and winding method are included in the dual active bridge transformer loss analysis process to enable optimal design at the initial design stage. Transformer loss analysis for dual active bridge with a switching frequency of 200 kHz and maximum output of 5 kW was executed, and elements necessary for design based on the number of turns on the primary side were graphed while maintaining the transformer turns ratio and window area. In particular, it was possible to determine the optimal number of turns and thickness of the transformer, and ultimately, the total loss of the transformer could be estimated.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2488-2498
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• 2021

The wall film-wise condensation plays an important role in the heat transfer processes of heat exchangers, refrigerators, and air conditioner. In the field of nuclear engineering, steam condensation is often utilized in safety systems to remove the core decay heat under both transient and accident conditions. In particular, passive containment cooling system (PCCS), are designed to ensure containment safety under severe accident conditions. A computational fluid dynamics (CFD) scale analysis has been conducted to calculate the heat transfer rate of the PCCS. However, despite the increase in computing power, there are challenges in the long-term transient simulation of containment using CFD scale codes. In this study, a heat structure coupling between the CFD and system analysis codes was performed to efficiently analyze PCCS. In addition, the component unstructured program for interfacial dynamics (CUPID) was improved to analyze the condensation behavior of ternary gas mixtures. Thereafter, the condensation heat transfer on the primary side was calculated using the improved CUPID and CFD code, whereas that on the secondary side was simulated using MARS. Both the coupled codes were validated against the CONAN facility database. Finally, conjugate heat transfer simulations with wall condensation in the presence of non-condensable gases were appropriately performed.