• Title/Summary/Keyword: 생산비용

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Characterization of various crystal planes of beta-phase gallium oxide single crystal grown by the EFG method using multi-slit structure (다중 슬릿 구조를 이용한 EFG 법으로 성장시킨 β-Ga2O3 단결정의 다양한 결정면에 따른 특성 분석)

  • Hui-Yeon Jang;Su-Min Choi;Mi-Seon Park;Gwang-Hee Jung;Jin-Ki Kang;Tae-Kyung Lee;Hyoung-Jae Kim;Won-Jae Lee
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.34 no.1
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    • pp.1-7
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    • 2024
  • β-Ga2O3 is a material with a wide band gap of ~4.8 eV and a high breakdown-voltage of 8 MV/cm, and is attracting much attention in the field of power device applications. In addition, compared to representative WBG semiconductor materials such as SiC, GaN and Diamond, it has the advantage of enabling single crystal growth with high growth rate and low manufacturing cost [1-4]. In this study, we succeeded in growing a 10 mm thick β-Ga2O3 single crystal doped with 0.3 mol% SnO2 through the EFG (Edge-defined Film-fed Growth) method using multi-slit structure. The growth direction and growth plane were set to [010]/(010), respectively, and the growth speed was about 12 mm/h. The grown β-Ga2O3 single crystal was cut into various crystal planes (010, 001, 100, ${\bar{2}}01$) and surface processed. The processed samples were compared for characteristics according to crystal plane through analysis such as XRD, UV/VIS/NIR/Spec., Mercury Probe, AFM and Etching. This research is expected to contribute to the development of power semiconductor technology in high-voltage and high-temperature applications, and selecting a substrate with better characteristics will play an important role in improving device performance and reliability.

Electrochemical Studies on the Corrosion Performance of Steel Embeded in Activated Fly Ash Blended Concrete (활성화된 플라이애쉬 혼입콘크리트의 철근부식거동에 관한 전기화학적 연구)

  • Song, Ha-Won;Lee, Chang-Hong;Lee, Kewn Chu;Velu, Saraswathy
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.6
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    • pp.97-108
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    • 2008
  • The use of fly ash to replace a portion of cement has resulted significant savings in the cost of cement production. Fly ash blended cement concretes require a longer curing time and their early strength is low when compared to ordinary Portland cement(OPC) concrete. By adopting various activation techniques such as physical, thermal and chemical method, hydration of fly ash blended cement concrete was accelerated and thereby improved the corrosion-resistance of concrete. Concrete specimens prepared with 10-40% of activated fly ash replacement were evaluated for their open circuit potential measurements, weight loss measurements, impedance measurements, linear polarization measurements, water absorption test, rapid chloride ion penetration test and scanning electron microscopy (SEM) test and the results were compared with those for OPC concrete without fly ash. All the studies confirmed that up to a critical level of 20-30% replacement; activated fly ash cement improved the corrosion-resistance properties of concrete. It was also confirmed that the chemical activation of fly ash better results than the other methods of activation investigated in this study.

Study on The Effect of Electrode Drying Temperature on The Silicon Electrode Characteristics of Lithium Secondary Batteries (전극 건조 온도가 리튬이차전지의 실리콘 전극 특성에 미치는 영향 연구)

  • Dong-Wan Ham;Myeong-Hui Jeong;Jeong-Tae Kim;Beom-Hui Lee;Hyeon-Mo Moon;Sun-Yul Ryou
    • Journal of the Korean Electrochemical Society
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    • v.27 no.3
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    • pp.97-104
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    • 2024
  • The electrodes of commercialized lithium secondary batteries are manufactured through a wet coating process, and the drying process (DC) is a very important factor as to electrode production speed and process cost. In this study, silicon anodes were manufactured under high-temperature (180 ℃) and low-temperature (50 ℃) DC to investigate the quality and the electrochemical performance of Si-electrodes according to DC. High-temperature DC can quickly evaporate the solvent in the Si-electrode slurry, improving the electrode production rate. However, this also causes the electrode composite to peel off from the current collector. As a result, the Si-electrode's adhesion weakened, and the electrode coating's quality deteriorated. In addition, the Si-electrode manufactured under high-temperature was found to have a thicker composite material than the Si-electrode manufactured under low-temperature. Si-electrodes manufactured under high-temperature had higher sheet resistance and lower electrical conductivity than those manufactured under low-temperature. Consequently, the Si-electrode manufactured under low-temperature showed 152.5% superior cycle performance compared to the Si-electrode manufactured under high-temperature. (Discharge capacities of Si-electrodes manufactured under high-temperature and low-temperature DC were 844 and 1287 mAh g-1, respectively, after 300 cycles). Establishing the DC of Si-electrodes can easily provide new perspectives to improve the quality and stability of Si-electrodes.

Research Trends on the Structure and System of Nickel Catalysts for Low-Temperature Processes in Highly Efficient Carbon Dioxide Methanation Reactions (고효율 이산화탄소 메탄화 반응을 위한 저온 공정용 니켈 촉매 구조 및 시스템 연구 동향)

  • Jaewon Jang;Jungpil Kim
    • Korean Chemical Engineering Research
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    • v.62 no.4
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    • pp.312-326
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    • 2024
  • This review comprehensively reviews the latest research trends in nickel catalysts for low-temperature CO2 methanation reactions, with special emphasis on catalyst synthesis and reactor design for low-temperature CO2 methanation reactions. In addition to the previously reported catalyst synthesis method of impregnation, the effects of structural and chemical properties of catalysts synthesized by solvothermal synthesis and electrospinning on CO2 methanation reactions were analyzed. We also discuss the potential for process cost reduction and scale-up based on 3D catalyst structures and catalyst stacked reactor designs to improve reaction efficiency. It is found that the efficiency of the CO2 methanation reaction can be maximized by controlling the oxygen vacancies and crystal structure of the catalyst through an innovative catalyst synthesis method, and by increasing the active area of nickel through the 3D structure of the catalyst and the reactor design. It is expected that this review will serve as the basis for the field of converting natural gas into CH4, which can be used as a substitute for natural gas while reducing CO2, a major greenhouse gas.

Biosynthesis of Medium-chain-length Polyhydroxylalkanoate Using Extracted Oil from Spent Coffee Grounds (커피 찌꺼기 오일을 이용한 medium-chain-length Polyhydroxylalkanoate생합성)

  • Hui-Yeon Kwon;Jong-Sik Kim;Chung-Wook Chung
    • Journal of Life Science
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    • v.34 no.10
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    • pp.682-690
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    • 2024
  • This study aimed to produce medium-chain-length polyhydroxyalkanoates (mcl-PHA) using oil extracted from spent coffee grounds (SCG) as a carbon source. The highest oil yields, 14.40%(w/w) and 14.49%(w/w), were achieved with an extraction time of 2 hr and an SCG/n-hexane ratio of 15:1. The fatty acid composition of the extracted SCG oil (EOC) primarily consisted of linoleic acid (45.08%), palmitic acid (35.56%), oleic acid (8.62%), and stearic acid (7.62%). Pseudomonas sp. HY61, isolated from soil, was used to biosynthesize mcl-PHA composed of 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate using EOC. Under optimal flask conditions, the highest cell growth and mcl-PHA accumulation were observed with 5 g/l EOC, 72 hr, with NH4Cl as the nitrogen source, at pH 7, 25℃, and a C/N ratio of 15:1. Batch fermentation resulted in a dry cell weight (DCW) of 0.92 g/l and mcl-PHA of 0.17 g/l after 72 hr. In contrast, fed-batch fermentation, with additional supplementation of EOC and NH4Cl at 18, 30, and 42 hr, increased the DCW to 2.85 g/l and mcl-PHA accumulation to 0.67 g/l, approximately three times higher than batch fermentation. Gas chromatography confirmed that the mcl-PHA structure was consistent across both fermentation modes. The synthesized mcl-PHA had higher molecular weight and thermal decomposition temperatures compared to other mcl-PHA, suggesting its potential applications in packaging and biomedical fields. This study offers an economical approach for mcl-PHA production using waste EOC and Pseudomonas sp. HY61.

Development of Gate Non-stop system using RFID(900MHz) Technology (RFID(900MHz) 기술을 이용한 GATE 무정차 시스템 개발)

  • Choi, Gi-Jin;Kim, Young-Mi;Choi, Jae-Sin;Lee, Chang
    • 한국ITS학회:학술대회논문집
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    • 2008.11a
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    • pp.570-574
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    • 2008
  • The 'gate non-stop system utilizing RFID (900MHz)', which is the core of this research, is the system which connects RFID to recognize the vehicle information without stopping when a vehicle (trailer) passes a gate to carry in or out containers in a terminal and automatically provides the container information provided by the terminal for the RFLDU device installed in the vehicle.In order to design and implement this, the RFID technical section uses a UHF band (900MHz) RFID tag and a reader and implements a RFID middleware and an application program for smooth data collection and execution (operation). In addition, the system stability was verified through experiments and operations of the system implemented in this research at real harbors/quays, and based on the verified result, the maximization of vehicle (trailer) and terminal productivity and the reduction of distribution cost are expected.

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Self-Powered Smart Jump-Rope to Transform an Intensive Physical Activity into Electricity-Generating Fun Experience (고강도의 줄넘기 운동을 지속 가능하고 즐거운 경험으로 만들기 위한 에너지 자립형 스마트 줄넘기)

  • Jo, Jonghyun;Yeo, Jungjin;Park, Heajeong;Ryu, Munho;Yang, Yoonseok
    • Journal of the HCI Society of Korea
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    • v.9 no.2
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    • pp.13-21
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    • 2014
  • Jump-rope is a simple and effective exercise, but its intensive exercise load and monotonous pattern make it difficult to perform consistent workout. On the other hand, jumping rope accompanies large amount of kinetic energy which can be converted into electrical energy. In this study, we designed and implemented a self-powered jump-rope which can support the low-power embedded Bluetooth system inside it. The embedded system wirelessly transmits the acceleration data measured during jumping-rope exercise to a smartphone. We also developed a smartphone app which can count the number of jumps and provide real-time feedback with sound and animated graphic effects in a game context. Pilot test using the prototype smart jump-rope verified that it can be useful to motivation for the jump-rope exercise and make the exercise more effective by providing users with precise information about their exercise. We expect that the developed self-powered jump-rope will change the exercise from an intensive physical activity into electricity-generating fun experience combined with smartphone game, which maximize the benefit of the consistent jump-rope exercise.

Direction for Improving Cost Estimation and Management of Construction Projects : Comparing to Australian System (건설공사 공사비 예측 및 관리기술 발전방향 : 호주 사례를 중심으로)

  • Ji, Sae-Hyun;Park, Moon-Seo;Lee, Hyun-Soo;Yoon, You-Sang
    • Korean Journal of Construction Engineering and Management
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    • v.9 no.2
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    • pp.170-181
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    • 2008
  • Cost of construction project have to be estimated based on drawing before execution. Cost estimate and check would be performed numerously for preparing general outline of requirements and determining the budget at conceptual planning stage, for obtaining decision on every matter related to design, specification, construction and cost at design stage, and for predicting bidding cost. Thus, importance of cost estimation cannot emphasize too much in construction. However, there are lack of standard estimation method, process, and cost analysis method, that square foot estimation method is as used as eyer, in Korea. Thus, This research present the direction for improving cost estimation and management in construction; It is demanded that establishing standard data base methodology, multi-level database model CUBE, and standard cost planning process, choosing cost estimation methodology according to objectives and cost planning process, and making more experts.

The Sour Gas Treatment and Removal Technology (사워가스 처리기술 및 제거기술)

  • Kim, Y.C.;Cho, J.D.;Oh, C.S.
    • Journal of Energy Engineering
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    • v.25 no.1
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    • pp.171-176
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    • 2016
  • Sour gas is natural gas or any other gas containing significant amounts of hydrogen sulfide ($H_2S$). Natural gas is usually considered sour gas if there are more than 5.7 milligrams of $H_2S$ per cubic meter of natural gas, which is equivalent to approximately 4 ppm by volume under standard temperature and pressure We have surveyed on the treatment and removal technology of sour gas, sour gas include a lot of hydrogen sulfide($H_2S$), Carbon dioxide($CO_2$), utane($C_4H_{10}$) and mercaptan($C_nH_{4n-1}SH$) etc. We need high technology for development for these kinds of raw gases and we should specially take care of treating and removal of theses raw gases. Therefor we are going to describe about these kinds of raw gases and about methods how to treat these kinds of gases.

유도 결합 플라즈마 스퍼터 승화법을 이용한 Cr 박막 증착 및 특성 분석

  • Choe, Ji-Seong;Ju, Jeong-Hun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.243-243
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    • 2012
  • 화석연료를 대체할 새로운 청정 에너지원의 요구가 높아지고 있는 현 시점에서 고효율, 무공해, 무소음 등의 장점으로 인해 친환경적 에너지원으로 연료전지의 수요가 증가하고 있다. 연료전지 분리판으로 고밀도 흑연을 종래에 가공하여 제작하였는데, 가공이 어렵고, 비용이 크게 들며, 대량생산이 어렵다는 등의 문제로 스테인리스강을 위주로 한 금속 분리판 개발이 이루어지고 있다. 본 연구에서는, 낮은 가격, 고속 증착, 우수한 가공성, 높은 기계적 강도 및 전기전도도, 화학적 안정성 및 내식성을 충족시키기 위하여 스테인리스 강박(0.1 mm이하)에 보호막으로 CrN을 선택하였다. 저가격화를 위하여 새로운 증착원인 스퍼터-승화형 소스의 가능성을 유도 결합 플라즈마에 Cr 봉을 직류 바이어스 함으로써 시도하였다. 10 mTorr의 Ar 유도 결합 플라즈마를 2.4 MHz, 400 W로 유지하면서 직류 바이어스 전력을 120 W (615 V, 0.19 A) 인가하였을 때 10분 동안의 증발양이 0.35 gr으로 측정이 되어 그 가능성을 확인할 수 있었다. 또한 OES(Optical emission spectrometer)를 이용하여 RPS로 방전시킨 고밀도 ICP를 측정한 결과 842.4 nm, 811.4 nm, 772.3 nm 등의 파장에서 높은 intensity를 갖는 peak을 찾을 수 있었고, 이 peak 들은 Ar 중성의 peak임을 확인할 수 있었다. ICP+DC bias로 Cr rod를 가열하는 공정에서의 plasma를 OES로 측정한 결과 Ar 중성의 peak은 감소하고, 520.5 nm, 425.5 nm, 357.7 nm 등의 파장에서 높은 intensity를 갖는 peak을 찾을 수 있었으며, 이 peak들은 Cr 중성의 peak임을 확인할 수 있었다. OES 측정 data를 토대로 공정 중의 rod type Cr target의 교체 주기를 예측할 수 있고 공정 중 실시간 감시가 가능할 것으로 기대된다.

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