• Journal of the Korea Society of Computer and Information
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• v.23 no.10
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• pp.73-80
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• 2018

The shared economy began with the concept of sharing the physical and intellectual assets of individuals with others. Nowadays, the concept of shared economy is becoming one of the industries as an enterprise type. Especially, with the development of the Internet and smart devices, various forms of shared economy have been developed in accordance with the need of sharing of individual income. Digital content is also a shareable commodity and it is seeking to utilize it as an item of shared economy. Accordingly, when digital contents are used as a shared economy, there are various possible threats -security threats that may arise in the course of transactions, potential for theft, alteration and hacking of contents. In this paper, we propose transaction method and content protection method using block chain-ethereum technology to reduce security threats and transparent transactions that can occur in digital contents transactions. Through the proposed method, the trust of the consumer and the supplier can be measured and the encryption can be performed considering the characteristics of the data to be traded. Through this paper, it is possible to increase the transparency of smart transaction of digital contents and to reduce the risk of content distortion, hacking, etc.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.971-978
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• 2018

This paper deals with the design and implementation of a limiter, which is a key component of the Ku-band radar system. The limiter design with the multi-pin diode switch was complemented by wideband signal attenuation, and realized the physical implementation. In the test result of implemented limiter, when the pin diode switch is all off, it is possible to transmit the incoming signal without distortion. Also when the pin diode switch is turned on sequentially, the input signal is attenuated about 20dB or more step by step. Finally when all of them were turned on, attenuation about 50dB or more were measured for a wide bandwidth(1000MHz) in Ku-band.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2132-2135
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• 2005

Cylindrical type air core pulse transformers capable of passing high voltage and energy pulse waveforms with high efficiency and low distortion require a much more delicate design balance of physical dimensions and electrical parameters than iron or ferrite core units. The structure of an air core high voltage pulse transformer is relatively simple, but considerable attention is needed to prevent breakdown between transformer windings. Since the thickness of the windings in spiral type is on the order of sub-millimeter, field enhancement at the edge of the windings is very high. It is, therefore, important to find proper electrical insulation Parameter to make the system compact. Several shapes of the winding are considered for air core pulse transformer development. In this paper, we are described design procedure, parameters measure and experiment results of air core type HV pulse transformer.

• Korean Institute of Interior Design Journal
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• v.19 no.1
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• pp.121-127
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• 2010

Technological development are now encouraging new concepts in various fields of design, including material applications. Metal can be considered as the major material that represents modern design and technology since the industrial revolution. The objective of this study was to understand characteristics of metal as design material and various application methods in interior design. This study first examined basic qualities of metal and its history used in architectural design. Secondly, based on three qualities of metal such as physical, chemical, and mechanical the authors have analyzed projects built within recent 10 years regarding aspects of metal qualities, treatments. As results projects that uses a combination of two or more qualities and treatment seem to have a more interesting affects in interior space. Moreover, each affects are related to these four design keyword: visual distortion, de-materialization, hi-technology, and time-concept. The framework developed is hopes to be used as a basic design guideline, where metal is considered not just as a mere interior finish material but as a major creative source and inspiration in interior design.

• Korean Institute of Interior Design Journal
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• v.19 no.1
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• pp.27-36
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• 2010

The purpose of this study is to define concept and characteristics of "Unphenomenon", the design concept conceived by Shiro Kuramata who is a world renowned Japanese interior designer and to explore how his ideas were materialized in his works. This study 1) examines his experience during his childhood reflected in his essay The scenery of the Unphenomenon' and training in Kuwazawa Design Institute that made Shiro Kuramata a true interior designer, and also considers how his design philosophy had been built up and realized under the unique social situation at the time. 2) defines the concept and characteristics of "Unphenomenon" as substance of his design philosophy by surveying remarks in his books and comments made by people around him in press interviews. 3) concludes his own design method and uniqueness by analyzing his works based on them. As a result, the study has founded that 1) transparency as recognitive realization of existence and non-existence: non-existence of physical property, connotation, ambiguity 2) expression of uncommonness by correcting and reinterpreting common prejudices: flotation, distortion of scale and shape 3) realization of insubstantiality by removing and replacing material and shape: replacement into light, removal of the structure, multiple layers of meaning.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.117-122
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• 2018

3D printing technology and its applications have grown rapidly in academia and industry. We consider a 3D printing system designed for the selective laser sintering (SLS) method, which is one of the powder bed fusion (PBF) techniques to build up the final product by layering sintered powder slices. Thermal distortion of printing products is a critical challenge in 3D printing. This study investigates temperature-dependent conformational behaviors of 3D printed samples of sintered poly-ether-ether-ketone (PEEK) powders using molecular dynamics simulations. The wear and chemical resistance properties of PEEK are understood, as it is a well-known biocompatible material used for implants. However, studies on physical phenomena at nanoscale in PEEK are rarely published in public. We simulate dissipative particle dynamics to elucidate how a cavity regime forms in PEEK at different system temperatures. We demonstrate how PEEK structures deform subject to the system temperature distribution.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.138-146
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• 2019

PURPOSE. Comparing the accuracy of casts produced from digital workflow to that of casts produced from conventional techniques. MATERIALS AND METHODS. Whole arch alginate (ALG) and polyvinyl siloxane (PVS) impressions were taken with stock trays and custom trays, respectively. The ALG impressions were poured with type III dental stone, while the PVS impressions were poured with type IV dental stone. For the digital workflow, IOS impressions were taken and physical casts were produced by 3D printing. In addition, 3D printed casts were produced from images obtained from a laboratory scanner (LS). For each technique, a total of 10 casts were produced. The accuracies of the whole arch and separated teeth were virtually quantified. RESULTS. Whole arch cast accuracy was more superior for PVS followed by LS, ALG, and IOS. The PVS and ALG groups were inferior in the areas more susceptible to impression material distortion, such as fossae and undercut regions. The LS casts appeared to have generalized errors of minor magnitude influencing primarily the posterior teeth. The IOS casts were considerably more affected at the posterior region. On the contrary, the IOS and LS casts were more superior for single tooth accuracy followed by PVS and ALG. CONCLUSION. For whole arch accuracy, casts produced from IOS were inferior to those produced from PVS and ALG. The inferior outcome of IOS appears to be related to the span of scanning. For single tooth accuracy, IOS showed superior accuracy compared to conventional impressions.

• Current Applied Physics
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• v.18 no.11
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• pp.1431-1435
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• 2018

Using first-principles calculations, we successfully investigate the electrochemical performance of the monoclinic $NaMnO_2$ for the sodium ion batteries. $NaMnO_2$ possesses a voltage window of 3.54-2.52 V and theoretical reversible capacity of $136mAh\;g^{-1}$. Besides, we find that the metallicity of the monoclinic $NaMnO_2$ gradually increases during Na extraction. Moreover, the computational Na migration energy barrier in the monoclinic $NaMnO_2$ is 0.18 eV, ensuring ideal conductivity and reversible capacity. Although the Jahn-Teller distortion effects limit the enhancement of the reversible capacity of the monoclinic $NaMnO_2$, it is still a right cathode material for the sodium ion batteries. The computational results are well in consistent with the experimental investigations.

• Journal of Veterinary Clinics
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• v.39 no.2
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• pp.65-69
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• 2022

A 5 day-old Warmblood foal was presented with a quarter crack due to the dam accidentally stepping on his left hind foot. Physical examination revealed the vertical crack included the coronary band of the medial side of the left hind hoof (quarter crack) with the lower pastern avulsion wound. Different from adult horses, the foot of the 5 day-old foal lacked adequate hoof wall thickness for stainless steel wire insertion and hoof size for a reinforcing fabric to be applied. Therefore, the authors decided to stabilize the edges of the cracked wall only by the polymethyl methacrylate (PMMA) composites without wiring and a reinforcing fabric application; and gluing a plastic shoe that was reshaped to protect the lower pastern and to spread pressure to other parts of the hoof when bearing weight. Disinfection and a supportive bandage were applied daily for 2 weeks. A month after the hoof crack accident, lameness had diminished. The quarter crack in this foal was treated successfully by the application of the composites three times with a reshaped gluing shoe, with approximately a month interval over the 4 months. After 4 months, it presented a successful functional recovery and needed no further treatment. When followed up 8 months after the accident, it revealed successful outcomes without hoof shape distortion and unbalanced hoof/limb growth.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.38.3-38.3
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• 2021

We are developing an optomechanical design of infrared telescope for the CubeSat and Unmanned Aerial Vehicle (UAV) which adapts the Linear Astigmatism Free- Three Mirror System in the confocal off-axis condition. The small entrance pupil (diameter of 40 mm) and the fast telescope (f-number of 1.9) can survey large areas. The telescope structure consists of three mirror modules and a sensor module, which are assembled on the base frame. The mirror structure has duplex layers to minimize a surface deformation and physical size of a mirror mount. All the optomechanical parts and three freeform mirrors are made from the same material, i.e., aluminum 6061-T6. The Coefficient of Thermal Expansion matching single material structure makes the imaging performance to be independent of the thermal expansion. We investigated structural characteristics against external loads through Finite Element Analysis. We confirmed the mirror surface distortion by the gravity and screw tightening, and the overall contraction/expansion following the external temperature environment change (from -30℃ to +30℃).