• Journal of Technologic Dentistry
• /
• v.35 no.2
• /
• pp.121-126
• /
• 2013

Purpose: The aim of this research was to investigate difference in shear bond strengths of full-contour zirconia layered with porcelain. Methods: Disk-shaped (diameter: 12.0 mm; height: 3.0 mm) zirconia were randomly divided into six groups according to the surface conditioning method to be applied (N=90, n=15 per group): group 1-contol group(ZC); group 2-airborne particle abrasion with $50-{\mu}m\;Al_2O_3(5A)$; group $3-50-{\mu}m\;Al_2O_3$ + liner(5AL), group $4-110-{\mu}m\;Al_2O_3(1A)$; group $5-110-{\mu}m\;Al_2O_3$ + liner(1AL); group 6-liner(LC). On each block, zirconia porcelain was build up according to manufacturer's instructions. All samples were fixed with measuring jigs and shear bond strength were measured with Universal testing machine. Collected data were analyzed using SPSS(Statistical Package for Social Sciences) Win 12.0 statistics program. Results: LC showed the highest value($29.92{\pm}2.55$ MPa) and ZC showed the lowest value($13.22{\pm}1.37$ MPa). Zirconia liner and Alumina oxide groups was significantly higher shear bond strength than control(p<0.05). 5A (without liner $22.18{\pm}2.37$, with liner $22.84{\pm}1.74$ MPa) was higher shear bond strength than $110{\mu}m$ (without liner $20.18{\pm}2.38$, with $20.71{\pm}2.67$). Conclusion: Surface treatments may have advantage in bond strength improvement for full-contour zirconia layered with porcelain.

• Smart Structures and Systems
• /
• v.31 no.1
• /
• pp.1-11
• /
• 2023

Assessment of the compressive strength of concrete plays a major role during formwork removal and in the prestressing process. In concrete, temperature changes occur due to hydration which is an influencing factor that decides the compressive strength of concrete. Many methods are available to find the compressive strength of concrete, but the maturity method has the advantage of prognosticating strength without destruction. The temperature-time factor is found using a LM35 temperature sensor through the IoT technique. An experimental investigation was carried out with 56 concrete cubes, where 35 cubes were for obtaining the compressive strength of concrete using a universal testing machine while 21 concrete cubes monitored concrete's temperature by embedding a temperature sensor in each grade of M25, M30, M35, and M40 concrete. The mathematical prediction model equation was developed based on the temperature-time factor during the early age compressive strength on the 1^st, 2^nd, 3^rd and 7^th days in the M25, M30, M35, and M40 grades of concrete with their temperature. The 14^th, 21^st and 28^th day's compressive strength was predicted with the mathematical predicted equation and compared with conventional results which fall within a 2% difference. The compressive strength of concrete at any desired age (day) before reaching 28 days results in the discovery of the prediction coefficient. Comparative analysis of the results found by the predicted mathematical model show that, it was very close to the results of the conventional method.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.661-662
• /
• 2006

On the contrary of a conventional motor with very narrow air-gap, it is difficult to calculate the accurate magnetic field distribution and the performance of an air-cored superconducting motor by 2 dimensional analysis, which does not use high permeability material except outer machine shield. This paper aims to do analysis of magnetic field and force distribution from the 3 dimensional modelling of a 1MW class superconducting synchronous motor. Especially, the field coil composed of Bi-2223 high-temperature superconductor and the outer machine shield are modelled by finite element analysis software according to their structures and the self-inductance and Lorentz force are calculated based on the 3 dimensional magnetic field calculation.

• Journal of KIISE
• /
• v.42 no.8
• /
• pp.979-989
• /
• 2015

Machine to Machine (M2M) technology has gained attention due to the fast diffusion of Internet of Things (IoT) technologies and smart devices. Most wireless network experts believe that Bluetooth Low Energy (BLE) Communications technology in an iBeacon network has amazing advantages in terms of providing communication services at a low cost in smartphone applications. Specifically, BLE does not require any pairing process during its communication phases, so it is possible to send a message to any node without incurring additional transmissions costs if they are within the BLE communication range. However, BLE does not require any security verification during communication, so it has weak security. Therefore, a security authorization process would be necessary to obtain customer confidence. To provide security functions for iBeacon, we think that the iBeacon Message Encryption process and a Decryption (Authorization) process should be designed and implemented. We therefore propose the BLE message Authorization Mechanism based on a One Time Password Algorithm (BLE-OTP). The effectiveness of our mechanism is evaluated by conducting a performance test on an attendance system based on BLE-OTP.

• Nuclear Engineering and Technology
• /
• v.54 no.7
• /
• pp.2444-2452
• /
• 2022

The field-programmable gate array (FPGA) is gaining popularity in industrial automation such as nuclear power plant instrumentation and control (I&C) systems due to the benefits of having non-existence of operating system, minimum software errors, and minimum common reason failures. Separate functions can be processed individually and in parallel on the same integrated circuit using FPGAs in comparison to the conventional microprocessor-based systems used in any plant operations. The use of FPGAs offers the potential to minimize complexity and the accompanying difficulty of securing regulatory approval, as well as provide superior protection against obsolescence. Wireless sensor networks (WSNs) are a new technology for acquiring and processing plant data wirelessly in which sensor nodes are configured for real-time signal processing, data acquisition, and monitoring. ZigBee (IEEE 802.15.4) is an open worldwide standard for minimum power, low-cost machine-to-machine (M2M), and internet of things (IoT) enabled wireless network communication. It is always a challenge to follow the specific topology when different Zigbee nodes are placed in a large network such as a plant. The research article focuses on the hardware chip design of different topological structures supported by ZigBee that can be used for monitoring and controlling the different operations of the plant and evaluates the performance in Vitex-5 FPGA hardware. The research work presents a strategy for configuring FPGA with ZigBee sensor nodes when communicating in a large area such as an industrial plant for real-time monitoring.

• Journal of the Korean Society of Industry Convergence
• /
• v.9 no.4
• /
• pp.277-283
• /
• 2006

As the products such as HDD, Notebook, PDA, and Mobile Phone become smaller and thinner, the radius of threads as well as holes for assembling those products become smaller, even down to 1mm. To produce such small holes and thread efficiently, multi tapping is highly necessitated. However the multi tapping characteristics is not well known because its complicated cutting mechanism and thus the quality of the produced holes and threads is not well studied yet. In this paper, experiments have been conducted for small-radius threads using M2 and M2.6 and M3 cold forming tap to investigate multi tapping process using several useful signal such as torque and Z-axis encoder pulse. The surface and profile of the machined threads have been magnified and observed through a SEM.

• Nuclear Engineering and Technology
• /
• v.56 no.6
• /
• pp.2190-2194
• /
• 2024

The study investigates the dose-dependent direct X-ray sensing characteristics of Brucinium benzilate (BB) and N-acetylglycine (NAG) organic crystals. BB and NAG were prepared as a slurry and deposited as a thick film on a patterned metal electrode. The X-ray induced photocurrent response was examined for various exposure doses using an intraoral pulsed 70 keV X-ray machine connected to a source meter. Subsequently, the morphological properties and thickness of the thick films were analyzed using scanning electron microscopy (SEM). At a photon energy of 70 keV, the attenuation coefficient values for NAG and BB crystals were determined to be approximately 0.181 and 0.178 cm²/g, respectively. The X-ray stopping power of the crystals was measured using a suniray-2 X-ray imaging system. To evaluate the responsiveness of the sensors, the photocurrent sensitivity and noise equivalent dose rate (NED) were calculated for both thick films. The findings demonstrated a noteworthy capability of sensing low doses (mGy), thereby suggesting the potential application of these organic materials in X-ray sensor development.

• Journal of Digital Convergence
• /
• v.14 no.7
• /
• pp.21-27
• /
• 2016

Big Data is gathering all the attention from every business community. Pervasive use of machine-to-machine (M2M) applications and mobile devices bring an explosion of data. By analyzing this data, the private and public sectors can benefit in the areas of cost reduction and productivity. The Korean government is actively pursuing Big Data initiatives to promote its usage. This paper aims to select industries which fit for the development of Big Data with a verification of the experts. The analytic hierarchy process (AHP) is applied to systematically derive the opinion of more than 50 professionals. Medical / welfare, transportation / warehousing, information and communications / information security, energy, the financial sector have been identified as promising industries. The results can be utilized in developing Big Data best practices thus contributing industrial development.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.5
• /
• pp.1101-1108
• /
• 2018

This study is a study of the school zone safety system of the platform part in which processing between device and the application, gateway function processing, and application and service function are cooperatively processed. The device part is the beacons that are supported when the student moves in the school zone. And the section of application is a service announcement that applies to smartphones. Finally, the children's protection area sign shows the number of students registered at the gateway. Gateways operate in two types. The first type is a gateway installed to identify the movement of elementary school students. The second type is a gateway to identify students who have passed through the front door of the school. The IoT platform handles various service functions, child protection area panel support and student counter processing functions.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11c
• /
• pp.613-622
• /
• 2000

Watering operation for oyster mushroom growing houses is regarded as drudgery and time consuming farm operation for growers. Most of mushroom growing beds in oyster mushroom growing houses are designed as two-row with four floor beds, therefore the watering and ventilation between the bed floors are much difficult for farmers because of its structural design. The study aimed to reduce the watering operation and improve the mushroom growing environment through the humidification and air supply on mushroom growing beds. Results showed that appropriate size of nozzle is between 0.8~0.5ml/s for the humidification and higher than the 2.0ml/s for the watering. The optimum water supply pressure was regarded as between 1.0~2.0MPa and the uniform distribution of droplet on the bed showed on air flow speed of 14m/s. The prototype was equipped with twin nozzle with. the humidification nozzle of 0.85ml/s and watering nozzle of 5.0ml/s, and the air blast fan with the air speed of 10m/sec in each air spout. In the field test in a practical scale mushroom growing house, it was well operated dependant on the set desire by a electric control unit. The machine can be practically used as air blast watering and air blast humidification for oyster mushroom growing farms without manual.