• 한국연안방재학회지
• /
• 제5권4호
• /
• pp.173-182
• /
• 2018

As the research about increasing the efficiency of dredging soil transport, the technology, which reduce the friction between pipe wall and fluid in the pipe and disturbed generating pipe blockage, has been developed. So for the purpose of applying this technology to real construction site, main test has been tried at the real scale test in field. As a test result, this paper will show 30% flow efficiency increasing by permitted electro magnetic force to the pipe. And test result was evaluated as a ultra sonic velocity profiler. To propose the design technique and the execution manual of the high efficiency dredging material transport technic, this research have confirmed flow status changing depending on a soil material kind under electro-magnetic field and analyze the effect of electro-magnetic field which affects to each dredged soil material transportation. For achieving this research, EMF(Electro-Magnetic Field) generator is installed on the dredger(20,000HP) and through monitored flow status, dredging soil flow rate and sampled material specification is confirmed. Also dredger operating condition is measured and dredger power for soil transportation, hydraulic gradient and flow rate are compared, as transportation efficiency is calculated by this parameter, it is possible to check transportation efficiency improvement depending on each dredged soil material under electro-magnetic field. To verify the technique of dredged soil transfer using electromagnetic field, which is the core technique of the high efficiency dredged soil transfer, and the technique of expert system for pipeline transfer and the flow state. This could lead to a verification of transfer efficiency according to the characteristics of the dredged soil (sand, clay, silt) and the transfer distance (5km, 10km, 15km), which is planned to be used for a technology development of pump power reduction and long-distance transfer applying the high efficiency dredged soil transfer technology.

• 센서학회지
• /
• 제22권1호
• /
• pp.1-17
• /
• 2013

Metal oxides designed for application in conductometric gas sensors and approaches used for synthesis of metal oxides with improved gas sensing characteristics are discussed in present article.

• 한국재료학회지
• /
• 제32권3호
• /
• pp.132-138
• /
• 2022

Zintl phase Mg₃Sb₂ is a promising thermoelectric material in medium to high temperature range due to its low band gap energy and characteristic electron-crystal phonon-glass behavior. P-type Mg₃Sb₂ has conventionally exhibited lower thermoelectric properties compared to its n-type counterparts, which have poor electrical conductivity. To address these problems, a small amount of Sn doping was considered in this alloy system. P-type Mg₃Sb₂ was synthesized by controlled melting, pulverizing, and subsequent vacuum hot pressing (VHP) method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate phases and microstructure development during the process. Single phase Mg₃Sb₂ was successfully formed when 16 at.% of Mg was excessively added to the system. Nominal compositions of Mg_3.8Sb_2-xSn_x (0 ≤ x ≤ 0.008) were considered in this study. Thermoelectric properties were evaluated in terms of Seebeck coefficient, electrical conductivity, and thermal conductivity. A peak ZT value ≈ 0.32 was found for the specimen Mg_3.8Sb_1.994Sn_0.006 at 873 K, showing an improved ZT value compared to intrinsic one. Transport properties were also evaluated and discussed.

• 한국건축시공학회지
• /
• 제23권1호
• /
• pp.1-9
• /
• 2023

본 연구에서는 보편적으로 건물의 옥상 등에 사용되는 폴리 우레탄 방수재의 바탕구조물의 함수정도와 시공환경조건에 따른 하자원인을 분석하기 위한 것으로 바탕판의 함수조건에 따른 부착강도, 표면상태를 육안관찰하였고, 온도, 습도의 양생조건에 따라서 방수재 도막의 기계적 성능을 평가하였다. 실험결과 바탕판의 함수상태가 10%이상일 때 도막의 부착이 이뤄지지 않음을 확인하였고, 온습도 조건이 20℃, 80% RH일때는 기초물성이 모두 확보되었으나, 40℃, 60% RH일 때 표면에 기포가 관찰되었으며, 40℃, 80% RH일 때 건조도막 기초물성이 KS F 3211 성능기준이하로, 우레탄 방수재 도포에 있어 시공환경조건의 하자원인 중 바탕판의 함수조건 및 양생 시 절대습도가 중요한 요인임을 확인하였다.

• 청정기술
• /
• 제19권4호
• /
• pp.388-392
• /
• 2013

현재 인듐-주석-산화물(Indium-Tin-Oxide, ITO)은 디스플레이 제품에 투명 전극으로 사용된다. 하지만 인듐과 주석의 자원고갈 문제와 ITO 제조 공정에 많은 에너지가 소비되어 최근에는 ITO 대체물질의 개발과 ITO 재사용 및 재활용에 관한 연구가 요구되고 있는 실정이다. 이러한 상황에서 ITO를 재활용 하게 되면 수치상으로 환경부하 값의 변화 추이를 확인하기 위해서는 전과정 평가 기법을 이용한 전과정 평가가 매우 적절하다. 따라서 전과정 평가 수행을 위해 공정상에서 투입물질과 생성물질을 구분하고, 데이터 베이스(DB)를 적용하여 환경성 평가 결과를 영향 범주별로 계산하였으며, 34%를 폐기함에 따라 각각 해당하는 환경부하 값이 계산되었다. 화학당량적으로 ITO의 양을 계산하여 환경부하 값을 결정할 경우, 산성 물질과 자원고갈에 해당하는 값들이 계산되었고, ITO를 1 ton 생산하여 34%를 폐기할 경우 $ 476를 땅에 묻는 결과가 도출되었다.

• 한국건설관리학회논문집
• /
• 제9권2호
• /
• pp.108-116
• /
• 2008

현재 건설현장에서는 인력수급의 어려움과 숙련공의 노령화의 해법으로 건설 자동화가 추진되고 있다. 특히, 건축물의 대형화 및 고층화에 따라 양중작업의 중요성이 높아지면서 작업의 효율성을 향상시킬 수 있도록 타워크레인을 대상으로 한 많은 자동화연구가 진행 중이다. 타워크레인을 이용한 양중작업의 자동화를 위해서는 부재의 관성과 풍하중에 의한 진동을 제어해야 하는데, 제어하기에 앞서 진동을 예측하는 것은 매우 어렵다. 따라서 본 연구에서는 타워크레인과 부재를 대상으로 동적 모델링을 실시하고 시뮬레이션을 통해 부재의 동적 진동을 분석하였다. 그 결과, 작업조건에 따른 발생하는 부재의 최대진동폭과 특징을 분석하였다. 그리고 분석자료를 바탕으로 부재의 특성에 따라 양중작업 자동화가 가능한 풍속기준을 판단할 수 있는 방안을 제시하였다.

• 한국전기전자재료학회논문지
• /
• 제27권4호
• /
• pp.203-208
• /
• 2014

In this study, Sputtering method was used to grow Al-dopes ZnO films on a CIGS absorber layer, in order to examine the effect of TCO on properties of CIGS solar cell devices. Structural, electrical and optical properties were investigated by varied thickness of Al-dopes ZnO films. Also, relation to the application as a window layer in CIGS thin film solar cell were studied. It was found that the electrical and structural properties of ZnO:Al film improved with increasing its thickness. However, the optical properties degraded. Jsc of the fabricated CIGS based solar cells was significantly influenced by the variation of the ZnO:Al window layer thickness. Because ZnO:Al window layer is one of the Rs factors in CIGS solar cell. Rs has the biggest influence on efficiency characteristic. In order to obtain high efficiency of CIGS solar cell, ZnO:Al window layer should be fabricated with electrically and optically optimized.

• 한국전기전자재료학회논문지
• /
• 제26권7호
• /
• pp.503-509
• /
• 2013

In this study, $Cu(In_{1-x},Ga_x)Se_2$ (CIGS) thin films were prepared on the Mo coated soda-lime glass by the DC magnetron sputtering and a subsequent selenization process. For the selenization process, selenization rapid thermal process(RTP) with cracker cell, which was helpful to smaller an atomic of Se, was adopted. To make CIGS layer, they were then annealed with the cracked Se. Based on this selenization method, we made several CIGS thin film and investigated the effects of In deposition time, and selenization time. Through x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM), it is found that the Mo/In/CuGa structure and the high sputtering power shows the dominant chalcopyrite structure and have a uniform distribution of the grain size. The CIGS films with the In deposition time of 5 min has the best structure due to the smooth surface. And CIGS films with the selenization time of 50 min show good crystalline growth without any voids.

• Journal of Electrochemical Science and Technology
• /
• 제7권2호
• /
• pp.179-184
• /
• 2016

The interface between the surface of a cathode material and the electrolyte gives rise to surface reactions such as solid electrolyte interface (SEI) and chemical side reactions. These reactions lead to increased surface resistance and charge transfer resistance. It is consequently necessary to improve the electrochemical characteristics by suppressing these reactions. In order to suppress unnecessary surface reactions, we coated cathode material using polypropylene (PP). The PP coating layer effectively reduced the SEI film that is generated after a 4.3 V initial charging process. By mitigating the formation of the SEI film, the PP-coated Li[(Ni_0.6Co_0.1Mn_0.3)_0.36(Ni_0.80Co_0.15Al0.05)_0.64)]O₂(NCS) electrode provided enhanced transport of Li⁺ ions due to reduced SEI resistance (R_SEI) and charge transfer resistance (R_ct). The initial charge and discharge efficiency of the PP-coated NCS electrode was 96.2 % at a current density of 17 mA/g in a voltage range of 3.0 ~ 4.3 V, whereas the efficiency of the NCS electrode was only 94.7 %. The presence of the protective PP layer on the cathode improved the thermal stability by reducing the generated heat, and this was confirmed via DSC analysis by an increased exothermic peak.

• 한국재료학회지
• /
• 제32권6호
• /
• pp.287-292
• /
• 2022

Magnesium-antimonide is a well-known zintl phase thermoelectric material with low band gap energy, earth-abundance and characteristic electron-crystal phonon-glass properties. The nominal composition Mg_3.8-xZn_xSb₂ (0.00 ≤ x ≤ 0.02) was synthesized by controlled melting and subsequent vacuum hot pressing method. To investigate phase development and surface morphology during the process, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were carried out. It should be noted that an additional 16 at. % Mg must be added to the system to compensate for Mg loss during the melting process. This study evaluated the thermoelectric properties of the material in terms of Seebeck coefficient, electrical conductivity and thermal conductivity from the low to high temperature regime. The results demonstrated that substituting Zn at Mg sites increased electrical conductivity without significantly affecting the Seebeck coefficient. The maximal dimensionless figure of merit achieved was 0.30 for x = 0.01 at 855 K which is 30% greater than the intrinsic value. Electronic flow properties were also evaluated and discussed to explain the carrier transport mechanism involved in the thermoelectric properties of this alloy system.