• 한국수소및신에너지학회논문집
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• 제32권1호
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• pp.1-10
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• 2021

Water electrolysis technology, which generates hydrogen using renewable energy resources, has recently attracted great attention. Especially, the polymer electrolyte membrane water electrolysis system has several advantages over other water electrolysis technologies, such as high efficiency, low operating temperature, and optimal operating point. Since research that analyzes performance characteristics using test bench have high cost and long test time, however, model based approach is very important. Therefore, in this study, a system model for water electrolysis dynamics of a polymer electrolyte membrane was developed based on MATLAB/Simulink®. The water electrolysis system developed in this study can take into account the heat and mass transfer characteristics in the cell with the load variation. In particular, the performance of the system according to the stack temperature control can be analyzed and evaluated. As a result, the developed water electrolysis system can analyze water pump dynamics and hydrogen generation according to temperature dynamics by reflecting the dynamics of temperature.

• Computers and Concrete
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• 제28권5호
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• pp.479-486
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• 2021

Reinforced concrete (RC) slabs are exposed to several static and dynamic effects during their period of service. Accordingly, there are many studies focused on the behavior of RC slabs under these effects in the literature. However, impact loading which can be more effective than other loads is not considered in the design phase of RC slabs. This study aims to investigate the dynamic behavior of two-way RC slabs under sudden impact loading. For this purpose, 3 different simply supported slab specimens are manufactured. These specimens are tested under impact loading by using the drop test setup and necessary measurement devices such as accelerometers, dynamic load cell, LVDT and data-logger. Mass and drop height of the hammer are taken constant during experimental study. It is seen that rigidity of the specimens effect experimental results. While acceleration values increase, displacement values decrease as the sizes of the specimens have bigger values. In the numerical part of the study, artificial neural networks (ANN) analysis is utilized. ANN analysis is used to model different physical dynamic processes depending upon the experimental variables. Maximum acceleration and displacement values are predicted by ANN analysis. Experimental and numerical values are compared and it is found out that proposed ANN model has yielded consistent results in the estimation of experimental values of the test specimens.

• Advances in aircraft and spacecraft science
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• 제9권5호
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• pp.377-400
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• 2022

The aim of this work is a numerical comparison (FEM) between lattice pyramidal-core panel and honeycomb core panel for different core thicknesses. By evaluating the mid-span deflection, the shear rigidity and the shear modulus for both core types and different core thicknesses, it is possible to define which core type has got the best mechanical behaviour for each thickness and the evolution of that behaviour as far as the thickness increases. Since a specific base geometry has been used for the lattice pyramidal core, the comparison gives us the opportunity to investigate the unit cell strut angle giving the higher mechanical properties. The presented work considers a detailed FEM modelling of a standard 3-point bending test (ASTM C393/C393M Standard Practice). Detailed FEM modelling addresses to detailed discretization of cores by means of beam elements for lattice core and shell elements for honeycomb core. Facings, instead, have been modelled by using shell elements for both sandwich panels. On lattice core structure, elements of core and facings are directly connected, to better simulate the additive manufacturing process. Otherwise, an MPC-based constraint between facings and core has been used for honeycomb core structure. Both sandwich panels are entirely built of Aluminium alloy. Prior to compare the two models, the FEM sandwich panel model with lattice pyramidal core needs to be validated with 3-point bending test experimental results, in order to ensure a good reliability of the FEM approach and of the comparison. Furthermore, the analytical validation has been performed according to Allen's theory. The FEM analysis is linear static with an increasing midspan load ranging from 50N up to 500N.

• 한국전자통신학회논문지
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• 제17권2호
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• pp.317-324
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• 2022

본 논문에서는 일반 캐리어의 기능을 고려하여 캐리어의 단점 및 이용할 때의 불편한 점의 내용을 토대로 보완 및 개선을 위해 다양한 편리성 기능을 가진 스마트 캐리어를 연구하였다. 스마트폰 앱을 통해 캐리어에 LED와 모터잠금장치를 설치하고 on/off로 간단하게 제어하는 블루투스 인식 및 제어기능, 로드셀 센서를 캐리어 내부에 설치하여 물품을 넣었을 때 무게를 감지하여 LCD panel에 측정된 값을 보여주는 무게감지 기능, 블루투스와 경보기를 캐리어에 설치하고, 비콘과 거리를 설정하여 설정 거리 값을 벗어나면 경보시스템이 발생하여 도난 및 분실을 방지하는 기능을 갖춘 스마트 캐리어를 제작 및 실험하였다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2021년도 제64차 하계학술대회논문집 29권2호
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• pp.491-492
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• 2021

현대사회의 물류 현장에서 근로자가 직접 물류를 분류하는 작업을 하거나 상하차 작업을 진행하고 있다. 본 논문에서 제안하는 자율주행 로봇을 이용한 물류 분류 시스템은 물류 운반 로봇과 컨베이어 벨트로 구성된다. 물류 운반 로봇은 경로 설정 및 장애물 감지가 가능한 자율주행 기능을 가지며, 컨베이어 벨트는 하차된 물류의 무게 측정과 배송 가격을 표시하는 기능을 가진다. 본 연구의 결과는 근로자들의 노동 강도와 육체적 또는 정신적인 피해로 인해 발생하는 산업재해의 발생률을 감소시킬 수 있는 기대와 심야 시간에 부족한 인력을 보충하여 24시간 물류센터를 가동할 수 있는 가능성을 가진다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.423-424
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• 2021

이 논문에서는 수면 환경을 감지하는 센서들로부터 데이터를 수집하고 이를 바탕으로 수면 환경을 최적으로 조절하여 숙면을 취할 수 있도록 도와주는 시스템을 제안한다. 수면 환경 분석은 로드셀을 통한 뒤척임 감지에 의한 수면 단계 판단을 기본으로 하고 온도, 습도, 조도 등의 데이터를 바탕으로 온열 장치, 가습기, 블라인드 등을 제어하여 숙면을 취할 수 있는 환경을 조성한다. 수면 상태에 따른 수면 환경 제어는 기상하기 쉬운 수면 상태를 유도함으로써 기상 시에 피로감을 줄일 수 있다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2023년도 제68차 하계학술대회논문집 31권2호
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• pp.661-664
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• 2023

이 프로젝트의 목표는 공유 공간에서의 고객 이용 시간 관리를 향상하기 위해 라즈베리 파이와 센서 기술을 활용한 자동 시간 체크 시스템의 개발입니다. 이 시스템은 로드셀, 진동 감지 센서, 그리고 LiDAR 센서, 이 세 가지 센서를 활용해 의자에서 사용자의 존재 여부를 감지하고, 사람과 물건을 구별하며, 사용자가 의자에서 일어나는 시점을 파악합니다. 특히, 고객이 의자에 앉게 되면 시스템이 자동으로 시간을 체크하여 실시간으로 이용 시간을 측정하게 됩니다. 이렇게 수집된 정보는 웹 기반의 사용자 인터페이스를 통해 제공되어, 이용 시간 관리가 보다 편리해집니다.

• Steel and Composite Structures
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• 제49권4호
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• pp.393-405
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• 2023

In this paper, the energy absorption capability of a novel cruciform composite lattice structure was evaluated through the simulation of compression tests. For this purpose, several test samples of Polylactic acid cellular reinforced with continuous glass fibers were prepared for compression testing using the additive manufacturing method of material extrusion. Using a conventional path design for material extrusion, multiple debonding is probable to be occurred at the joint regions of adjacent cells. Therefore, an innovative printing path design was proposed for the cruciform lattice structure. Afterwards, quasistatic compression tests were performed to evaluate the energy absorption behaviour of this structure. A finite element model based on local material property degradation was then developed to verify the experimental test and extend the virtual test method. Accordingly, different combinations of unit cells' dimensions using the design of the experiment were numerically proposed to obtain the optimal configuration in terms of the total absorbed energy. Having brilliant energy absorption properties, the studied cruciform lattice with its optimized unit cell dimensions can be used as an energy absorber in crashworthiness applications. Finally, a cellular structure will be suitable with optimal behavior in crush load efficiency and high energy absorption.

• 한국지반신소재학회논문집
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• 제22권4호
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• pp.83-92
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• 2023

In this study, we conducted verification of key influencing factors during cone penetration testing using the developed Mini Cone Penetration Tester (Mini-CPT), and compared the experimental results with empirical formulas to validate the equipment. The Mini-CPT was designed to measure cone penetration resistance through a Strain Gauge, and the resistance values were calibrated using a Load Cell. Moreover, the influencing factors were verified using a model ground constituted in a soil box. The primary influencing factors examined were the boundary effect of the soil box, the distance between cone penetration points, and the cone penetration speed. For the verification of these factors, the experiment was conducted with the model ground having a relative density of 63.76% in the soil box. It was observed that the sidewall effect was considerably significant, and the cone penetration resistance measured at subsequent penetration points was higher due to the influence between penetration points. However, within the speed range considered, the effect of penetration speed was almost negligible. The measured cone penetration resistance was compared with predicted values obtained from literature research, and the results were found to be similar. It is anticipated that using the developed Mini-CPT for constructing model grounds in the laboratory will lead to more accurate geotechnical property data.

• 소성∙가공
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• 제33권1호
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• pp.5-11
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• 2024

The development of a next-generation hydrogen compressor, a key component in the expansion of hydrogen charging infrastructure, is in progress. In order to improve compression efficiency and durability, it is important to optimize the precision forming and shearing processes of the diaphragm, which is the bellows unit cell, as well as the optimization of diaphragm shape itself. In this study, we aim to show that die and process design technology that can synchronize the inner and outer shearing points of the diaphragm for the precision forming of product can be constructed based on a numerical simulation. First, the damage model that can predict the fracture points will be determined using the shear load and shear zone measurements obtained by performing a blanking test of AISI-633 stainless steel. Next, we will explain the overall procedure based on numerical analysis model how to determine the shearing points according to the deformation pattern of urethane die for various shearing die design.