• Earthquakes and Structures
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• v.15 no.4
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• pp.411-417
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• 2018

To solve the seismic response problem of a vertical floating roof tank with base isolation, the floating roof is assumed to experience homogeneous rigid circular plate vibration, where the wave height of the vibration is linearly distributed along the radius, starting from the theory of fluid velocity potential; the potential function of the liquid movement and the corresponding theoretical expression of the base shear, overturning the moment, are then established. According to the equivalent principle of the shear and moment, a simplified mechanical model of a base isolation tank with a swinging effect is established, along with a motion equation of a vertical storage tank isolation system that considers the swinging effect based on the energy principle. At the same time, taking a 150,000 m 3 large-scale storage tank as an example, a numerical analysis of the dampening effect was conducted using a vibration mode decomposition response spectrum method, and a comparative analysis with a simplified mechanical model with no swinging effect was applied.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.556-560
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• 2017

A hemoglobin/silver nanoparticle heterolayer was fabricated for bioelectronic device with electrochemical signal-enhancement effect. As a device element, a hemoglobin, the metalloprotein, contained the heme group that showed the redox property was introduced for charge storage element. For electron transfer facilitation, a silver nanoparticle was introduced for electrochemical signal facilitation, the hemoglobin was immobilized onto Au substrate using chemical linker 6-mercaptohexanoic acid (6-MHA). Then, the silver nanoparticle was immobilized onto fabricated hemoglobin/6-MHA heterolayers by layer-by-layer (LbL) method. The surface morphology and surface roughness of fabricated heterolayer were investigated by atomic force microscopy (AFM). The redox property of hemoglobin/silver nanoparticle heterolayer was investigated by a cyclic voltammetry (CV) experiment for obtaining an oxidation potential and reduction potential. Moreover, for the assessing charge storage function, a chronoamperometry (CA) experiment was conducted to hemoglobin/silver nanoparticle-modified heterolayer electrode using oxidation and reduction potentials, respectively. Based on the results, the fabricated hemoglobin/silver nanoparticle heterolayer showed that an increased charge storage effect compared to hemoglobin monolayer-modified electrode.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.04a
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• pp.339-344
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• 2008

The purpose of this study was to find out the residents' perceptive opinions of apartment housing environment and to contribute to develop a apartment unit plan in Daejeon City. This research was performed by a questionnaire survey method, 464 data was collected from apartment residents lived in about $85m^2$ unit with 3 rooms and the apartments was limited to the complexes within 3 years at Yuseong-gu and Seo-gu. By analyzing those data, findings are as follows: 1) Residents thought living room, kitchen and bathroom were importment space in a unit plan. They needed a storage function in an entrance and a intermediate room, and Anbang(materbed room) so did. L-DK plan type was very preferred. 2) Sub-kitchen was needed for a refrigerator of Kinch, the location of it was realted to a main kitchen and a uitility. the third room was needed for library, home office and storage space. 3) The enlargment remodeling of balcony was showed livingroom balcony or personal bedrooms at the time of occupancy. They needed the balcony near a kitchen or an utility to equip a storage facility. And residents were preferred to their taste rather than a choice of interior concept package services.

• Journal of Power Electronics
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• v.15 no.1
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• pp.202-215
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• 2015

This paper investigates the stability and performance of model predictive controlled active-front-end (AFE) rectifiers for energy storage systems, which has been increasingly applied in power distribution sectors and in renewable energy sources to ensure an uninterruptable power supply. The model predictive control (MPC) algorithm utilizes the discrete behavior of power converters to determine appropriate switching states by defining a cost function. The stability of the MPC algorithm is analyzed with the discrete z-domain response and the nonlinear simulation model. The results confirms that the control method of the active-front-end (AFE) rectifier is stable, and that is operates with an infinite gain margin and a very fast dynamic response. Moreover, the performance of the MPC controlled AFE rectifier is verified with a 3.0 kW experimental system. This shows that the MPC controlled AFE rectifier operates with a unity power factor, an acceptable THD (4.0 %) level for the input current and a very low DC voltage ripple. Finally, an efficiency comparison is performed between the MPC and the VOC-based PWM controllers for AFE rectifiers. This comparison demonstrates the effectiveness of the MPC controller.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1006-1017
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• 2015

This paper presents a finite control set model predictive control (FCS-MPC) strategy for the AC/DC matrix converter used in grid-connected battery energy storage system (BESS). First, to control the grid current properly, the DC current is also included in the cost function because of input and output direct coupling. The DC current reference is generated based on the dynamic relationship of the two currents, so the grid current gains improved transient state performance. Furthermore, the steady state error is reduced by adding a closed-loop. Second, a Luenberger observer is adopted to detect the AC input voltage instead of sensors, so the cost is reduced and the reliability can be enhanced. Third, a switching state pre-selection method that only needs to evaluate half of the active switching states is presented, with the advantages of shorter calculation time, no high dv/dt at the DC terminal, and less switching loss. The robustness under grid voltage distortion and parameter sensibility are discussed as well. Simulation and experimental results confirm the good performance of the proposed scheme for battery charging and discharging control.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.4
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• pp.761-768
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• 2019

In this paper, the aim is to develop plasma heater products combining the sterilization and purification functions of low-temperature plasma lamp method with the function of vertical heating system using wavelengths of vacuum magnetic (VU). Through this process, the government aims to improve the cultivation environment of crops in greenhouses or facility houses and to increase their storage capacity by increasing the freshness of stored crops such as free-temperature storage. In addition, real-time monitoring technologies will be incorporated that will enable users to identify and respond to changes within greenhouses in real time by utilizing ICT technologies.

• Structural Engineering and Mechanics
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• v.77 no.3
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• pp.369-381
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• 2021

The seismic responses of elevated tanks considering liquid-structure interaction are presented under horizontal earthquake. The scaled model tank is fabricated to study the dynamic responses of anchored tank and newly designed uplift tank with replaced dampers. The natural frequencies for structural mode are obtained by modal analysis. The dynamic responses of tanks are completed by finite element method, which are compared with the results from experiment. The displacement parallel and perpendicular to the excitation direction are both gained as well as structural acceleration. The strain of tank walls and the axial strain of columns are also obtained afterwards. The seismic responses of liquid storage tank can be calculated by the finite element model effectively and the results match well with the one measured by experiment. The aim is to provide a new type of tank system with vertical constraint relaxed which leads to lower stress level. With the liquid volume increasing, the structural fundamental frequency has a great reduction and the one of uplift tank are even smaller. Compared with anchored tank, the displacement of uplift tank is magnified, the strain for tank walls and columns parallel to excitation direction reduces obviously, while the one perpendicular to earthquake direction increases a lot, but the values are still small. The stress level of new tank seems to be more even due to uplift effect. The new type of tank can realize recoverable function by replacing dampers after earthquake.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.4
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• pp.255-261
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• 2011

In this paper, we propose a security-enhanced storing method for the voice data obtained during the flight. When an emergency occurs during flight, the flight data in the storage device such as DTS or Blackbox can be exposed to antagonist or enemy. Currently, zeroize function is embedded in these devices in order to prevent this situation. However, this could not be operated if the system is malfunctioned or the pilot is wounded in the emergency. In order to solve this problem, the voice data compressed by the ADPCM is encrypted in the proposed method composed of the AES algorithm and a reordering method. The simulation results show that the security for the voice date is further enhanced due to the proposed method.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.665-677
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• 2021

This study analyzed the optimization method of forest management to enhance economic and public functions, as well as the interrelationship among timber production, carbon storage, and water conservation functions in Mt.Gari leading forest management zone. For these purposes, a forest management planning model was developed using Multi-Objective Linear Programming. The model had an objective function to maximize the total NPV (Net Present Value) of weighted timber production, carbon storage, water conservation, and constraints to limit the rate of change in timber production, percentage of each age-class and tree species area, percentage of conifers and broad-leaved trees area in each management zone, minimum timber production and timber sales amount. Based on the description of forest inventory and the comprehensive plan of Mt.Gari, we analyzed stand information and management constraints of the study area. We compared management alternatives using different weights in the objective function. Therefore, the total NPV was maximized in the alternative considering the three functions in equal proportion, rather than the alternatives of maximizing only one function. When all three functions were considered simultaneously, timber production offset the carbon storage and water conservation, and carbon storage and water conservation interacted synergistically. However, when considering only two of the three functions, all combinations of functions demonstrated tradeoffs with one other. Therefore, we discovered that by considering all three functions equally, rather than only one or two functions, the economic and public values of the study area can be maximized.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.193-202
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• 2006

Objective To evaluate the influence of water storage on the mechanical properties of dental adhesives over 1 and 3 months. Materials and Methods Adhesive resin sheets were prepared by pouring either All-bond 2(AB), Clearfil SE Bond(SE) into a mold measuring $15{\times}15{\times}0.9mm$. After solvent in primer evaporation, the adhesives were light-cured and removed from the mold and divided in two pieces, trimmed to hourglass shape that were used to determine the micro-tensile strength(MTS). Another hourglass shaped metal mold measuring $2.0{\times}1.5mm$ in cross-section area was made to determine the Young's modulus(E). Adhesive specimens for Young's modulus(E) were prepared in the same method. Specimens were stored at $37^{\circ}C$ in distilled water and tested after 1 and 3 months. The data were analyzed by one-way ANOVA and Tukey's test. Results Water storage significantly decreased the micro-tensile strength(MTS) of AB and SE specimens after 1 and 3 months(P<0.05). The Young's modulus(E) were also decreased after water storage for 1 and 3 months, but statistically not significant in each group of AB and SE group respectively. Conclusions Long-term exposure of adhesive resin to water can cause reduction of mechanical properties. It may compromise resin/dentin bonds and affect longevity of restorations.