• Journal of the Korean Electrochemical Society
• /
• v.21 no.4
• /
• pp.68-79
• /
• 2018

Currently, hybridization of energy generator and storage devices is considered to be one of the most important energy-related technologies due to the possibility of replacing batteries or extending the lifetime of a batteries in accordance with increasing battery demand. This review aims to describe current progress on the mechanical energy generator and hybridization of energy generator and energy storage devices for self-powered electronics. First, the research trends related to energy generation devices using piezoelectric and triboelectric effect that convert physical energy into electric energy is introduced. In addition, integration of energy generators and energy storage devices is introduced. In particular, self-charging energy cells provide an innovative approach to the direct conversion of mechanical energy into electrochemical energy to decrease energy conversion loss.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.39 no.5
• /
• pp.297-311
• /
• 2021

Around the world, there is an increasing interest in Digital Twin cities. Although geospatial data is critical for building a digital twin city, currently-established spatial data cannot be used directly for its implementation. Integration of geospatial data is vital in order to construct and simulate the virtual space. Existing studies for data integration have focused on data transformation. The conversion method is fundamental and convenient, but the information loss during this process remains a limitation. With this, standardization of the data model is an approach to solve the integration problem while hurdling conversion limitations. However, the standardization within indoor space data models is still insufficient compared to 3D building and city models. Therefore, in this study, we present a comparative analysis of data models commonly used in indoor space modeling as a basis for establishing a generic indoor space feature model. By comparing five models of IFC (Industry Foundation Classes), CityGML (City Geographic Markup Language), AIIM (ArcGIS Indoors Information Model), IMDF (Indoor Mapping Data Format), and OmniClass, we identify essential elements for modeling indoor space and the feature classes commonly included in the models. The proposed generic model can serve as a basis for developing further indoor feature models through specifying minimum required structure and feature classes.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.27 no.4
• /
• pp.29-39
• /
• 2021

Purpose: As the need for a hospital specializing in infectious diseases has increased, construction is being promoted. Hospitals specializing in infectious diseases receive some state subsidies, but in the case of private hospitals, hospital operation efficiency should be considered to prevent cost loss. Therefore, we aim to derive a building plan for a general ward in a hospital specializing in infectious diseases that can be used not only in normal times but also in times of crisis. Methods: In this study, relevant literature review and field interviews were conducted with medical staff working in facilities designated as infectious disease hospitals. Results: The general ward building plan of the hospital specializing in infectious diseases was classified into three categories and presented. 'Spatial composition' for nursing unit and ward zoning, 'Spatial plan' for ward space conversion in normal times and crises, 'Bedroom plan' for effective dimensions and area of the ward. Implications: It can be used as a guideline when designing an infection-facility ward. And it can be a basis for inducing improvements to prevent infection in the ward of existing medical facilities.

• Nuclear Engineering and Technology
• /
• v.55 no.4
• /
• pp.1518-1527
• /
• 2023

A method was proposed for in-situ evaluating the thickness and resistivity of the oxide/hydroxide film formed on the surface of aluminum alloy exposed to sump water formed in the containment after a loss-of-coolant accident. The evaluation entailed fitting a model for the film impedance, which has film thickness and other variables describing the resistivity profile of the film along its thickness direction as fitting parameters, to the practically measured electrochemical impedance data. The obtained resistivity profiles implied that the films formed at pHs_25℃ 7, 8, 9, 10, and 11 all had a duplex structure; compared to the outer layer in contact with the solution, the inner layer of the film had a much higher resistivity and was inferred to be denser and provide most of the protectiveness of the film. Both the thickness and the total resistance of the film decreased with the increasing solution pH_25℃, suggesting that the films formed in more alkaline solutions had less protectiveness against corrosion, consistent with the increasing aluminum alloy corrosion rates previously identified.

• Nutritional Sciences
• /
• v.8 no.1
• /
• pp.3-9
• /
• 2005

Obesity can be defined as a metabolic disease due to an increased fat accumulation in the body caused by an imbalance of calorie intake and output The prevalence of obesity has increased substantially over the past 2-3 decades in developed and developing countries. The health impact of weight gain is so marked that obesity has now been classified as a major global public health problem In order to investigate the effect of diet conversion and oral administration of Platycodon grandiflorum extracts on the treatment of obesity, male Spraque-Dawley rats were divided into four groups: a group converted to normal diet (Control group), a group maintained high fat (30%) diet (H), and two groups with Platycodon grandiflorum extract added to the previously mentioned two groups. All animals were fed high fat diet for 7 weeks to induce the obesity. Then they were divided as mentioned above. Animals were fed experimental diet and Platycodon grandiflorum extract (150 mg/ml/rat/day) for 7 weeks. Body weight, adipose tissue weight (subcutaneous, epididymal, peritoneal fat pads) and serum lipids (total cholesterol and triglyceride) showed some differences among groups. The Platycodon grandiflorum feeding markedly decreased both body weight and adipose tissue weight in control group compared to H, high fat diet maintaining, group. Platycodon grandiflorum extracts significantly decreased the concentrations of serum lipids compared to H group. Fat cell numbers and sizes were significantly reduced in the oriental medicinal herb extract administrated group. Increased fatty acid binding protein (FABP) expression in high fat diet group was decreased by the dietary conversion to normal diet and the oral administration of Platycodon glandiflorum extracts. In contrast, there was no significant effect on FABP expression in the high fat maintenance group. In this study, the conversion from high fat diet to low fat or normal diet had a beneficial effect on body weight loss and serum lipid profiles. Dietary Platycodon glandiflorum extracts had an additive beneficial effect on the prevention and treatment of obesity.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.7
• /
• pp.944-950
• /
• 1993

Diodes and GaAs have been commonly used in a mixer design until recently. However, diodes are not preferred to use at the front-end of DBS receiver due to the conversion loss large noise. HEMT has larger conversion gain and better noise characteristics comparing with GaAs MESFET. This paper describes the design procedure, structure, and performance of a mixer, utilizaing HEMT designed by OKI Co. . A mixer configuration in which the local oscillator(LO) signal is applied to the gate is used. When the LO power is 0.01 dBm, the conversion gain of 3.7dB is obtained at IF and the 3 dB bandwidth is 400MMz.

• Journal of IKEEE
• /
• v.3 no.1 s.4
• /
• pp.69-78
• /
• 1999

In this paper, direct conversion receiver was designed to even harmonic anti-paralled diode pair ring mixer. Using a second harmonic component of LO instead of LO signal and RF signal are mixed by SHP(Sub Harmonic Pumped) mixer with anti-parallel diode pair. Canceling the harmonics of LO signal in ring mixer, SHP mixer using anti-parallel diode pair could mostly reduce the radiation of LO signal through a input port the most, good isolation characteristic, and low spurious characteristic by LO signal was shown over broad band. The produced SHP mixer showed LO/IF, RF/IF and LO/RF isolation was 24.6dB,36.2dB and 22.5dB respectively. And conversion loss was measured 15.6dB, IF output -35.6dBm with -20dBm RF input and 5.5dBm LO signal. 1dB compression point of If signal, in respect to RF signal, was found at the 0dbm RF signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.7 s.98
• /
• pp.681-689
• /
• 2005

This paper presents an ultra wide band(UWB) mixer using anti-parallel diode pair(APDP) with simulation and measurement results. The proposed mixer adopts the even-harmonic direct conversion mixing, which consists of a couple of filter, in-phase wilkinson power divider, wideband $45^{\circ}$ power divider, and APDP. The m mixer is operating over 3.1 to 4.8 GHz and producing quadrature(I/Q) outputs with a conversion loss of 18 dB and input third order intercept point($IIP_3$) of 15 dBm. I/Q outputs also have difference of about 0.5 dB and phase difference of ${\times}3^{\circ}$ and $P_{1dB}$ of 2 dBm.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.1
• /
• pp.121-126
• /
• 2013

Cycloconverter used as a power conversion device in the speed and torque control system of AC machines has the advantage of a simple control and a large torque at low speed. In addition, because a rectifier, a DC link, and an inverter are not installed, this system is simple and suitable for large power system. If a power conversion device, which is currently used as a propulsion motor of large vessel, is changed into cycloconverter, the system is simplified and then the installation costs can be significantly reduced. However, conventional cycloconverter has the increased harmonics because the power loss is large and the waveform of output voltage is distorted, due to the high-speed switching of power semiconductor devices. In order to improve these shortcomings, this paper describes a phase shifting filter which is composed of two inputs with different phases in the primary side and one output in the secondary one. As the voltage waveforms with two different phases are added and transformed into the secondary side, these outputs are close to sinusoidal waves. Thereby the voltage waveforms, which are applied to the propulsion motors, are improved and total harmonic distortions (THDs) are significantly reduced.

• Korean Journal of Optics and Photonics
• /
• v.14 no.5
• /
• pp.509-514
• /
• 2003

Mach-Zehnder interferometric wavelength converters with monolithically integrated semiconductor optical amplifiers (SOA's) have been fabricated and characteristics of wavelength conversion at 10 Gb/s have been investigated for wavelength span of 40 nm. The devices have been achieved by using a butt-joint combination of buried ridge structure type SOA's and passive waveguides. In the integration, a new method has been applied that removes p+InP cladding layer leading to high propagation loss and forms simultaneously the current blocking and the cladding layer using undoped InP. The module packaging has been achieved by using a titled fiber array for effective coupling into the tilted waveguide in the wavelength converter. Using the module, wavelength conversion with power penalty lower than 1 ㏈ at 10 Gb/s has been demonstrated for wavelength span of 40 nm. In addition, it is show that the module can provide 2R (re-amplification, re-shaping) operation by demonstrating the conversion with the negative penalty.