• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.25-26
• /
• 2023

The internal core material and external color of a sandwich panel have a significant impact on the performance of the sandwich panel. For use on roofs and walls, the internal core material and external color must be considered. Therefore, the surface and back side temperatures were measured for each exterior color and inner core material type. For the internal core materials, urethane foam and Expanded Poly Styrene(EPS), which are core materials mainly used in sandwich panels, were selected. As colors, black and ivory were selected according to brightness, and a total of five colors were selected: red, blue, and green, which are the three primary colors of light. As a result, there were differences in surface and temperature depending on the external color and type of internal core material. Regardless of the color, the temperature was measured lower for panels with urethane foam than for panels with an internal core of EPS. This is believed to have been influenced by the difference in thermal conductivity of urethane foam being 0.023W/(m·K) and that of EPS being 0.032W/(m·K). In addition, panels with a black exterior color were found to have higher surface and back temperatures than panels of other colors, and ivory-colored panels had lower back temperatures regardless of the core material. This is proportional to the brightness and light-absorbing characteristics.

• Nuclear Engineering and Technology
• /
• v.50 no.3
• /
• pp.356-367
• /
• 2018

A series of tests dedicated to station blackout (SBO) accident scenarios have been recently performed at the $Prim{\ddot{a}}rkreislauf-Versuchsanlage$ (primary coolant loop test facility; PKL) facility in the framework of the OECD/NEA PKL-3 project. These investigations address current safety issues related to beyond design basis accident transients with significant core heat up. This work presents a detailed analysis using the best estimate thermal-hydraulic code TRACE (v5.0 Patch4) of different SBO scenarios conducted at the PKL facility; failures of high- and low-pressure safety injection systems together with steam generator (SG) feedwater supply are considered, thus calling for adequate accident management actions and timely implementation of alternative emergency cooling procedures to prevent core meltdown. The presented analysis evaluates the capability of the applied TRACE model of the PKL facility to correctly capture the sequences of events in the different SBO scenarios, namely the SBO tests H2.1, H2.2 run 1 and H2.2 run 2, including symmetric or asymmetric secondary side depressurization, primary side depressurization, accumulator (ACC) injection in the cold legs and secondary side feeding with mobile pump and/or primary side emergency core coolant injection from the fuel pool cooling pump. This study is focused specifically on the prediction of the core exit temperature, which drives the execution of the most relevant accident management actions. This work presents, in particular, the key improvements made to the TRACE model that helped to improve the code predictions, including the modeling of dynamical heat losses, the nodalization of SGs' heat exchanger tubes and the ACCs. Another relevant aspect of this work is to evaluate how well the model simulations of the three different scenarios qualitatively and quantitatively capture the trends and results exhibited by the actual experiments. For instance, how the number of SGs considered for secondary side depressurization affects the heat transfer from primary side; how the discharge capacity of the pressurizer relief valve affects the dynamics of the transient; how ACC initial pressure and nitrogen release affect the grace time between ACC injection and subsequent core heat up; and how well the alternative feeding modes of the secondary and/or primary side with mobile injection pumps affect core quenching and ensure stable long-term core cooling under controlled boiling conditions.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1021-1022
• /
• 2011

This paper presents the double side PM synchronous motor/generator for core loss reduction in flywheel energy storage system. The use of double PM rotor causes the elimination of core loss in no-load state of machine. Because flywheel rotational speed is reduced by core loss, double PM rotor is very effective in flywheel system. This paper suggests two types of double side PM rotor, Halbach magnetized array and parallel magnetized array. And characteristic comparison according to thickness of rotor back core is performed.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.493-496
• /
• 2009

We report the EL property of blue and blue-violet emitting materials with anthracene moiety as well as a new core structure containing indenopyrazine. Non-doped device using one of indenopyrazine core derivatives was found to exhibit excellent blue-violet color purity of (0.173, 0.063), and narrow emission band of 42nm FWHM. One of anthracene core derivatives with bulky side group also exhibits excellent color coordinates (0.156, 0.088) and an external quantum efficiency of 7.18%.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.1
• /
• pp.52-57
• /
• 2008

In the transformer that is used for the contactless power transmission system, the primary and secondary sides are separated structurally unlike general transformers. When the contactless transformer is built, it forms relatively bigger air gap than the general transformer. Thus it is difficult to transfer energy from the primary side input to the secondary side output with high power efficiently because of low coupling coefficient. This paper proposes a contactless transformer using the rectangular type core that maintains high coupling coefficient even when it has relatively large air gap. The performance characteristics of the proposed transformer are compared with the transformer using general EE core to the air gap variation. The proposed contactless system using rectangular type core and dc-dc full bridge converter, and the system using EE core type and dc-dc full bridge converter are respectively implemented and their performance characteristics are verified by the simulation and experiment.

• Nuclear Engineering and Technology
• /
• v.47 no.5
• /
• pp.534-545
• /
• 2015

In the very high temperature reactor (VHTR), which is a next generation nuclear reactor system, ceramics are used as a fuel coating material and graphite is used as a core structural material. Even if a depressurization accident occurs and the reactor power goes up instantly, the temperature of the core will change only slowly. This is because the thermal capacity of the core is so high. Therefore, the VHTR system can passively remove the decay heat of the core by natural convection and radiation from the surface of the reactor pressure vessel. The objectives of this study are to investigate the heat transfer characteristics of natural convection of a one-side heated vertical channel with inserted porous materials of high porosity and also to develop the passive cooling system for the VHTR. An experiment was carried out using a one-side heated vertical rectangular channel. To obtain the heat transfer and fluid flow characteristics of the vertical channel with inserted porous material, we have also carried out a numerical analysis using a commercial Computational Fluid Dynamics (CFD) code. This paper describes the thermal performances of the one-side heated vertical rectangular channel with an inserted copper wire of high porosity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.5
• /
• pp.508-514
• /
• 2004

A fluxgate magnetic sensor consists of a solenoid excitation coil, pick-up coil, and magnetic core. We presents the effect of magnetic core shape in a micromachined fluxgate sensor. To observe the performance of fluxgate sensor with magnetic core side width and gap, side width of 125 ${\mu}{\textrm}{m}$, 250 ${\mu}{\textrm}{m}$, and 500 ${\mu}{\textrm}{m}$ were designed in a rectangular-ring shaped core and the gaps of 0 ${\mu}{\textrm}{m}$, 50 ${\mu}{\textrm}{m}$, and 100 ${\mu}{\textrm}{m}$ were also fabricated in a racetrack shaped core. The solenoid coils and magnetic core were separated by benzocyclobutane(BCB) which had high insulation and good planarization characters. Copper coil patterns of 10 ${\mu}{\textrm}{m}$ width and 6${\mu}{\textrm}{m}$ thickness were electroplated on Ti(300 $\AA$) / Cu(1500 $\AA$) seed layers. 3 ${\mu}{\textrm}{m}$ thick N $i_{0.8}$F $e_{0.2.}$(permalloy) film for the magnetic core was also electroplated under 2000 gauss to induce the magnetic anisotropy. The magnetic core had the high DC effective permeability of ∼1,300 and coercive field of ∼0.1 Oe. Because the magnetic cores of 500 ${\mu}{\textrm}{m}$ side width and 0 gap had a low magnetic flux leakage, high sensitivity of ∼350 V/T were measured at excitation condition of 3 $V_{P-P}$ and 2 MHz square wave. The power consumption of ∼14 ㎽ was measured. The fabricated fluxgate sensor had the very small actual size of 3.0${\times}$1.7 $\textrm{mm}^2$. When two fluxgates were perpendicularly aligned in terrestrial field, their two-axis output signals were very useful to commercialize an electronic azimuth compass for the portable navigation system.m.m.m.

• Journal of KSNVE
• /
• v.6 no.6
• /
• pp.827-834
• /
• 1996

The effect of pipe breaks in the secondary side is investigated as a part of the fuel assembly qualification program. Using the detailed dynamic analysis of a reactor core, peak responses for the motions induced from pipe breaks are obtained for a detailed core model. The secondary side pipe breaks such as main steam line and economizer feedwater line braksare considered because leak-before-break methodology has provided a technical basis for the elimination of double ended guillotine breaks of all high energy piping systems with a diameter of 10 inches or over in the primary side from the design basis. The dynamic responses such as fuel assembly shear force, bending moment, axial force and displacement, and spacer grid impact loads are carefully investigated. Also, the stress analysis is performed and the effect of the secondary side pipe breaks on the fuel assembly structural integrity under the faulted condition is addressed.

• Journal of The Korean Society of Integrative Medicine
• /
• v.9 no.4
• /
• pp.183-190
• /
• 2021

Purpose : The purpose of this study was to investigate the effect of side planks on the muscle thickness of the core muscles, external oblique, internal oblique, and transverse abdominis, and this study was conducted to compare whether side plank exercise according to the application of various unstable support surfaces increases the thickness by activating the action of the muscles. Methods : The subjects of this study were 30 healthy adults and were randomly and equally assigned to three groups by a random number table. All subjects were divided into three groups according to the application of an unstable support surface during the side plank(Group A = stable support, Group B = one unstable support, Group C = two unstable supports). The side plank exercise was performed 30 minutes a day, 3 times a week for a total of 4 weeks. The muscle thickness of the core muscle was measured before the intervention, 2 weeks, 4 weeks, and 3 times in total. All measured data were comparatively analyzed by repeated measures ANOVA and one-way ANOVA. The statistical significance level was set to .05. Results : The results of this study were as follows : 1. All muscles showed an interaction between training period and group. 2. There was a significant difference between the groups at the 2 weeks and 4 weeks of the internal oblique and transverse abdominis muscle measurements. Conclusion : The thickness of the abdominal muscle increased during the side plank exercise according to the support surface, and the thickness of the abdominal muscle increased the most during the side plank exercise on the unstable support surface. Therefore, it is thought that the addition of an unstable support surface will provide a more effective therapeutic effect on the thickness change of the abdominal muscle during side plank exercise.

• Journal of Power Electronics
• /
• v.16 no.3
• /
• pp.823-831
• /
• 2016

A high-efficiency method is proposed to suppress magnetic core imbalance in phase-shifted full-bridge (PSFB) converters. Compared with conventional solutions, such as controlling peak current mode (PCM) or adding DC blocking capacitance, the proposed method has several advantages, such as lower power loss and smaller size, because the additional current sensor or blocking capacitor is removed. A time domain model of the secondary side is built to analyze the relationship between transformer core imbalance and cathode voltage of secondary side rectifiers. An approximate control algorithm is designed to achieve asymmetric phase control, which reduces the effects of imbalance. A 60 V/15 A prototype is built to verify the proposed method. Experimental results show that the numerical difference of primary side peak currents between two adjacent cycles is suppressed from 2 A to approximately 0 A. Meanwhile, compared with the PCM solution, the efficiency of the PSFB converter is slightly improved from 93% to 93.2%.